Cretaceo en El Norte Del Peru

CRETACEOUS SYSTEMNORTHERN PERU

IN

VICTOR ~E.:BENAVIDES-CACERES

BULLETIN:OF THE:

dERICAN MUSEUM OF NATURAL ~:HISTORY`.UME 108 ARTICLE 4 NEW YORK; 1956

CRETACEOUS SYSTEM IN NORTHERN PERU

CRETACEOUS SYSTEM INNORTHERN PERU

VfCTOR E. BENAVIDES-CACERES

SUBMITTED IN PARTIAL FULFILLMENT OF THEREQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHY IN THEFACULTY OF PURE SCIENCECOLUMBIA UNIVERSITY

BULLETINOF THE

AMERICAN MUSEUM OF NATURAL HISTORY

VOLUME 108 : ARTICLE 4 NEW YORK 1956

BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORYVolume 108, article 4, pages 353-494, text figures 1-58,

plates 31-66, tables 1, 2

Issued April 9, 1956

Price: $3.50 a copy

CONTENTS

INTRODUCTION ...359General Statement ..359History of Explorations ..359Field Work . . ............... 361Acknowledgments . . ............... 361Geographic Setting ..362Tectonic Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362Pre-Cretaceous Geology . . . . . . . . . . . . . . . . . . . . . . . . . . 363

STRATIGRAPHY ...365General Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365Western Mountain Front. ................. 365

Chimti Sandstone. . . . . . . . . . . . . . . . . . . . . . . . . . . 365Santa Formation. ... .367Carhuaz Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 368Pariahuanca Limestone .. .369

Central Western Andes ....370Goyllarisquisga Formation ..370Chulec Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . 373Pariatambo Formation .. .375Jumasha Formation . . . . . . . . . . . . . . . . . . . . . . . . . . 376

Northern Western Andes . .. .378Inca Formation . . ... .378

Pulluicana Group. ..381Yumagual Formation... 381Mujarruin Formation . . .......... . 382

Quillquifian Group . . ...383Romiro6n Formation ...383Cofnor Formation . . .. .384

Otuzco Group ...384Cajamarca Formation .. .385Celendin Formation . ...386Chota Formation ...387

Marafi6n Valley ..388Crisnejas Formation . .. .388Rosa Formation ..390

Zones...390Zone of Valanginites broggsi . . . . . . . . . . . .. . . . . . . . . . . . 392Zone of Parahoplites nicholsoni. .392Zone of Kneemiceras raimondii ..394Zone of Oxytropidoceras carbonarium . . . . . . . . . . . . . . . . . . . . 395Zone of Ostrea (Lopha) scyphax ..395Zone of Paraturrilites lewesiensis. . 396Zone of Exogyra cf. Exogyra ponderosa . . . . . . . . . . . . . . . . . . 396Zone of Exogyra africana ..396Zone of A canthoceras chasca . . .. 396Zone of Coilopoceras jenksi . ..397Zone of Coilopoceras neweii . .. .397Zone of B-schiceras bilobatum . . . . . . . . . . . . . . . . . . . . . . . 397Zone of Lenticeras baltai . ...398

Geologic History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399Stratigraphic Sections ..401

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358 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 108

PALEONTOLOGY ..434General Statement ..434Systematic Paleontology ..435Phylum Mollusca. .435Subphylum Cephalopoda ..435

ClassNautiloidea.. 435Class Ammonoidea ..436

LiST OF REFERENCES ..488

INTRODUCTION

GENERAL STATEMENTINTENSIVE GEOLOGICAL ACTIVITY in northernSouth America has demonstrated the prev-alence and importance of the Cretaceoussystem ia this area. However, in spite of theearly efforts of von Buch, d'Orbigny, andKarsten, the Cretaceous strata and theirinvertebrate faunas are still very incom-pletely known. Most papers dealing with thestratigraphy of the Cretaceous have scantyand outdated paleontological information,and even the fewv recent works on the in-vertebrate fossil faunas lack adequate strati-graphic control. The need of "careful anddetailed paleontological study of well ex-posed sections" (Hedberg, 1942, p. 208) hasrepeatedly been stressed.One of the best-developed and most fossilif-

erous Cretaceous sequences of the continentis magnificently exposed in the northernAndes of Peru. A review of the literaturesuggested this area as a logical one for a de-tailed study of the stratigraphy and paleontol-ogy of the Cretaceous system.The purpose of this paper is: (1) to describe

the Cretaceous succession in the Andes ofnorthern Peru, establishing standard sectionsof reference and fossil zones; (2) to describeits cephalopod faunas and their stratigraphicdistribution; and (3) to summarize the geo-logical history of the area during the Cre-taceous.

HISTORY OF EXPLORATIONSAs early as 1839, Leopold von Buch (1839,

p. 2) was able to say in the introduction tothe description of the fossils collected byAlexander von Humboldt in Peru and NuevaGranada, "la collection de Mr. de Humboldtet ses observations prouvent, a ce qu'ilparoit, que de tels fait n'existent pas et fontvoir, que dans les montagnes des Andes equa-toriales la formation crayeuse est tout a faitpr6ponderante et developpe6 sur une echellegigantesque." Humboldt had traveledthrough northern Peru in 1802 and devotedone chapter in his "Ansichten der Natur" toa description of the plateau of Cajamarca. Hewas the first of a distinguished group oftravelers and naturalists who explored South

America during the early part of the nine-teenth century-Agassiz, Bompland, Bous-singault, Dana, Darwin, Forbes, Karsten,d'Orbigny, and Orton, to mention only thosewho contributed to the knowledge of theCretaceous system.

D'Orbigny (1842, 1851, 1853) concernedhimself especially with the Cretaceous faunasof Colombia, about which he said, "La faunecolombienne m'offre la plus grande resem-blance avec celle des terrain cretacees del'ancien monde" (1842, p. 25). Impressed bythe similarity of the Cretaceous faunas ofSouth America and those of Europe, he pos-tulated some paleogeographic explanations.The collections made in northern Peru by

J. Orton were studied by Hyatt (1875) whoremarked: "the apparent identity of manyof the forms with those of well knownEuropean species is surprising.... Thissmall collection has precisely the aspect of alot of Western European fossils."To this period belong also the journeys of

Antonio Raimondi, indefatigable naturalistand geographer who during nearly 50 yearsexplored most of the Peruvian territory. Hesent his collections of fossils, with carefulnotes about their location and even ages, toW. Gabb who published an important mono-graph (Gabb, 1877).

Gustav Steinmann opened a new stage inthe geological progress of Peru and SouthAmerica as a whole. He was the first to at-tempt systematic studies on the stratigraphyand paleontology of South America. His"Geologie von Peru" (1929) is a masterlytreatment of the fundamentals of Peruviangeology and an indispensable source ofreference. His collections, and those of earlierGerman travelers such as Sievers, Stubel, andReiss, were distributed among his studentsfor monographic treatment. Gerhardt (1897a)described the "Gault" fauna of Pariatambo;Paulcke (1903), the "Albian and Upper Cre-taceous" faunas of Peru; Neumann (1907),the Neocomian flora and fauna of the Limaenvirons and the "Albian, Cenomanian andSenonian" of central Peru. Sommermeier(1910, 1913) was in charge of the "Aptian andAlbian" faunas of northern Peru, while Schlag-intweit (1912) worked on the "Vraconian and

359

360 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 108

0

1.

FIG. 1. Index map and location of sections.

40

7

BENAVIDES: CRETACEOUS SYSTEM IN PERU

Cenomanian" of northern Peru, and Briiggen(1910) on the "Senonian" of northern Peru.Independently, Luithy (1918) described afauna similar to that studied by Briiggen.Between 1914 and 1921, J. A. Douglas

published the results of his "Geological sec-tions through the Andes of Peru and Bolivia,"the last one from the port of Callao to thePerene River, and in 1924 a traverse wasmade by the Ellsworth expedition, led byJ. T. Singewald (1925a, 1925b, 1927, 1928),from the port of Casma to eastern Peru; thecollections were studied by Knechtel,Richards, and Rathbun (1947).

Carlos I. Lisson published many paperson Peruvian Cretaceous fossils, collaboratedclosely with Steinmann, and published avaluable check list of Peruvian fossils(Liss6n and Boit, 1942).

In connection with the exploration anddevelopment of mining and petroleum re-sources, several regional studies were madewhich added information on the Cretaceoussystem of northern Peru. Stappenbeck (1924,1929) studied the Chicama Valley, outliningthe stratigraphy. Iddings and Olsson (1928)worked on the geology of northwestern Peru.In addition, Olsson published two mono-graphs on the Cretaceous of the AmotapeMountains (Olsson, 1934) and the Paitaregion (Olsson, 1944). McLaughlin (1924) in-vestigated the geology and physiography ofthe Peruvian Cordillera in central Peru.

J. V. Harrison, working on the geologyof central Peru, is the most active amongrecent workers listed in the bibliography.

Regional monographs that have an im-mediate bearing on the area discussed in thispaper are Kummel's (1948) reconnaissanceof the Contamana region in eastern Peru,Jenks's (1948) study of the Arequipa quad-rangle, and Newell's (1949) study of thegeology of the Lake Titicaca region.

Finally, Gerth (1932, 1935), Hedberg(1942), Olsson (1942b), Weaver (1942), Stille(1940), and Weeks (1947) considered theCretaceous system in northern Peru in theirefforts to synthesize the data on SouthAmerican geology.

FIELD WORKBetween August, 1951, and August, 1952,

the present writer spent nine months in thenorthern Andes of Peru; work was inter-

rupted during the months of January toMarch, the rainy season. Because geologicalmaps were wanting, much of the time wasspent in reconnaissance trips in an effort tolocate stratigraphic sections that were ade-quate for study. Twenty-one sections (fig. 1)were investigated in detail, and fossils werezonally collected. Most of the sections are inthe Cordillera Occidental, between Chota onthe north and Pomachaca on the south;three sections are along the Maraii6n River,one is in the mountain front (Tembladerasection) near the Pacific Ocean, and two(Carhuaz and Pariahuanca sections) arealong the Callejo6n de Huaylas. Most of thesections were measured by means of ajacob staff, one was measured with thealidade, and another, with the steel tape.

ACKNOWLEDGMENTSThis research was begun at the suggestion

of Prof. Norman D. Newell. His continuousencouragement and advice are deeply appreci-ated.The work was made possible by the

financial support of the International Petro-leum Company, Limited. Messrs. 0. C.Wheeler, A. L. Bell, and A. G. Fischer of thiscompany were particulary helpful. A supple-mentary grant was made available by theInstituto Geologico del Peru, through theinterest and good offices of its director, Ing.Jorge A. Broggi.

During the field work, Messrs. MoisesHinojosa and Aldo Rodriguez, students at theUniversidad Nacional de Arequipa, renderedinvaluable assistance. Many residents in thearea studied extended courtesies and hospi-tality to the writer's party; among them,Messrs. A. Knoch of Cajamarca, WenceslaoValera of Hacienda Marcamachay, WilfredoPorturas of Hacienda Santa Clara, and theMessrs. Rossel of Hacienda Jocos are espe-cially thanked.Much of the investigation was done in the

laboratories of Columbia University and theAmerican Museum of Natural History. Pro-fessor Thomas W. Amsden of the JohnsHopkins University kindly made availabletype specimens of Peruvian ammonites de-posited in that university.The writer is indebted to Profs. Marshall

Kay and John Imbrie of Columbia Univer-sity and Prof. William F. Jenks of the

1956 361

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY

University of Rochester for reading partsof the manuscript and for many helpfulcomments and advice. Thanks are also dueto Dr. Otto Haas for his advice on nomen-clatural problems, and to Mr. Robert Adling-ton for his counsel on photographic tech-niques.

GEOGRAPHIC SETTINGIn northern and central Peru, the Andean

Cordillera is best described as a broadplateau, 4000 meters high, about 200 kilo-meters wide, and with a north-northwesttrend, separated from the Pacific Ocean bya narrow and low coastal strip. This broadplateau has been deeply incised by two mainsubsequent rivers: the Marafi6n and theHuallaga. The portion of the Andean plateauwest of the Marafl6n River is known as theCordillera Occidental; it includes the con-tinental divide. The area between theMaraf6n, and Huallaga rivers is known asthe Cordillera Central, and east of theHuallaga River is the lower CordilleraOriental, which sends spurs into the Ucayaliplain, a part of the great Amazon plain.

In central Peru, the Andean plateau iscomparatively undissected; it is an erosionalremnant from which many of the large riversthat contribute to the Amazon River radiate.Because of its fairly undissected, compactnature, it was described as a "knot" (nudo dePasco) by Raimondi. In central Peru, thethree longitudinal d'ivisions of northern Perucannot be established.

In contrast to the great longitudinal riverseast of the continental divide, the rivers thatflow towards the Pacific are transverse, short,and with steep gradients, with one notableexception, the Santa River. In the initial200 kilometers of its course, the Santa Riverflows northward as a longitudinal river andseparates the Cordillera Blanca, a granodio-rite pluton which projects far above the highplateau and contains some of the highest peaksof the continent, on the east, and the Cordil-lera Negra to the west. This part of theSanta Valley is known as the "Callej6n deHuaylas"; at its lower end, the Santa Riverbends sharply west and takes a transversecourse.The present report is limited to the Cordil-

lera Occidental from Chota on the north to

Huaraz on the south, and to the Marafi6nGorge. Although two trips were made intothe Cordillera Central, no significant resultswere obtained. The coastal strip, wherelarge intrus"ives and complicated structurespredominate, was not studied, although a fewsections were investigated in the mountainfront.

TECTONIC SETTINGDuring Cretaceous time, the area now oc-

cupied by the Andean Cordillera was a site ofgeosynclinal behavior, contrasting with theless mobile Brazilian craton. The character-istics of this geosynclinal belt are as yetpoorly known.

In northern Peru (fig. 2), this geosynclinalbelt was characterized by the following maintectonic elements:

A. A narrow, elongated area in betweenthe present Huallaga and Maraft6n rivers,which subsided less than the areas towards

FIG. 2. Tectonic elements of northern Peru;the heavy discontinuous lines are the hypotheticalaxes of deposition during the early Cretaceous.

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VOL. 108362


the east and west. This narrow belt is herenamed the "Marafi6n geanticline"; its mobil-ity and spatial relationships changed con-tinuously and, at times, it stood high as aland and source of sediments-Marafionia.

B. Between Marafionia and the Braziliancraton there was a geosyncline, referred to asthe "eastern Peruvian geosyncline." Ourknowledge of the Cretaceous stratigraphyin this belt is due mainly to Kummel (1948)and Huff (1949).

C. West of the Marafl6n geanticline, therewas another geosyncline, referred to as the"western Peruvian geosyncline"; the majoraxis follows the present continental divide.This paper deals with the stratigraphy of theCretaceous system in part of this latter belt.

D. It is postulated that somewhere alongthe present coast line there were lands-sources of sediments and volcanics. Thisassumption is based on the following data:

1. The Amotape Mountains area stoodhigh during the early part of the Cretaceousand was covered by the sea only in Albiantime (Olsson, 1942b, p. 411).

2. The upper Albian-Turonian rocks alongthe present coastal belt are more coarselyclastic than their time equivalents in theCordillera Occidental.

3. In the westernmost sections of thelower Cretaceous studied by the writer(Chicama Valley and Carhuaz sections)there are tuffs and tuffaceous sedimentswhich could have come only from the west.Volcanic rocks are not known in the sectionsalong the Cordillera Occidental or along theMarafi6n River.

During the latest Senonian these westernlands were the source of a very thick sequenceof coarse red beds which were spread overthe western Andes. An unconformity at thebase of these red beds increases in magnitudetowares the west.

Analogy with better known geosynclinalareas suggests that these lands may havebeen volcano-bearing island arcs (Kay, 1951,p. 31). They are homologous in time andposition and may have been connected withthe "borderland of Paria" to the north of theEastern Venezuela Geosyncline, about whichHedberg (1950, p. 1176) said: "The expres-sion 'borderland of Paria' is used . . . toapply to any sort of land area or source of

sediments (including 'island arcs') which mayhave lain north of the [Eastern Venezuela]geosyncline and supplied sediments to it."

These tectonic features were not sharplydefined at all times. It is suspected, for in-stance, that in the late Cretaceous the wholebelt between the Brazilian craton and thewestern volcanic and source lands subsidedas a single geosyncline.

PRE-CRETACEOUS GEOLOGYIn northern Peru, the Cretaceous sedi-

ments rest disconformably on upper Jurassic,lower Jurassic, Triassic, and Pennsylvanianrocks (fig. 3). The stratigraphy of these pre-Cretaceous rocks is little known. The onlyangular unconformity on record is that be-tween the Albian Pananga formation and theunderlying Pennsylvanian rocks in the Amo-tape Mountains, in northwestern Peru (Ols-son, 1934, p. 7). Along the Cordilleras Cen-tral and Occidental, however, the rocks of theupper Paleozoic are essentially parallel with

1 'I Upper JurassicLower JurassicIkTriassicPennsylvanian L i

FIG. 3. Pre-Cretaceous paleogeologic map,northern Peru.

1956 363


those of the Cretaceous. "There is no indica-tion of an orogeny in Peru between thePaleozoic and the Mesozoic" (Newell et al.,1953, p. 23).The unconformity at the base of the Cre-

taceous was developed through time. While insome areas, as in the Lima area (Rivera,1951, p. 16), sedimentation apparently wascontinuous from the Jurasssic into the Cre-taceous, in others, as in Marafionia, the firstCretaceous sediments to overlap the olderrocks are, at the earliest, Aptian in age.The upper Jurassic is represented along the

coastal areas and in the Cordillera Occidentalby thick, fossiliferous shales, tuffs, and con-glomerates, designated here for the purposesof discussion as the "Chicama beds." Thesebeds are missing in the Amotape Mountainsand also disappear, apparently by erosion,from the Maraflon geanticline where theCretaceous rocks rest on lower Jurassic andeven on Triassic rocks. Also, it is very likelythat towards the axis of the Marano6n geanti-cline rocks older than Triassic underlie theCretaceous, for during the late Albian thisarea produced red-bed conglomerates (Rosaformation) made up of quartz pebbles andcobbles. Furthermore, Singewald (in Knech-tel et al., 1947, p. 27) reports sandstones,quartz conglomerates, and shales which reston "green chloritic schists" in Pueblo Viejo,Huinuco, and which are overlain by "mas-sive limestones" with middle Albian fossils.The present writer suspects that these"sandstones, quartz conglomerates andshales" belong to the Cretaceous, and thatthe "green chloritic schists" are pre-Meso-zoic

Lower and upper Jurassic rocks have beenreported from the Huallaga River, on theeastern side of the Marafi6n geanticline

(Huff, 1949, p. 4). Marafnonia began to devel-op during the late Jurassic.

In the Andes of northern Peru, there is noevidence for a "Nevadan" orogeny or for agreat crustal disturbance other than wide-spread continental emergence, as postulatedby several authors (Hedberg, 1942, p. 205;Kummel, 1948, p. 1231). This statement issupported by the following facts:

1. In the Cordilleras Central and Occi-dental of northern and central Peru, theCretaceous rests disconformably, withoutdistinct angular relationships, on upperJurassic, lower Jurassic, Triassic, and Permi-an sediments. The angularity of the Saraya-quillo (Jurassic) and the Cushabatay (Cre-taceous) formations in eastern Peru (Kum-mel, 1948, p. 1231) has been recently inter-preted by Huff (1949, p. 7), in the light ofregional studies, as being of only local andslight significance.

2. The transgressive basal Cretaceous sedi-ments (Chimui and Goyllarisquisga forma-tions) are composed of extremely clean,mature, well-sorted, probably wind-winnowedquartz-sandstones that indicate, rather,conditions of tectonic quiescence at the timeof deposition.

3. When conglomerates are present at thebase of the Cretaceous, they are very thin(in Celendin they are 40 meters thick) andare made exclusivlely of reworked indigenousrocks.

4. Volcanic rocks are present in thewesternmost studied sections, both in theJurassic and in the Cretaceous, and althoughthey are more abundant in the former sys-tem, they indicate only that that area was oneof eugeosynclinal behavior during bothJurassic and Cretaceous times.

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STRATIGRAPHY

GENERAL STATEMENTCRETACEOUS SEDIMENTS are the most abun-dant and important rocks in the northernAndes of Peru. Older rocks are found, espe-cially along the deep trench of the Maraft6nRiver and along the western mountain front.Younger rocks are represented mainly by ig-neous intrusives and volcanic rocks that coversome large areas.The Cretaceous system in northern and

central Peru can be summarized as follows:1. It overlies a regional unconformity

which, along the Marafi6n axis, represents aconsiderable hiatus (Triassic-Albian at least)although without angular relationships.

2. The lower part of the Cretaceous se-quence is characterized by very clean quartz-sandstones and brackish-water depositswhich attain a maximum of 2000 meters inthe Callej6n de Huaylas area.

3. The clastic non-marine rocks are over-lain, with transgressive relationships, bymarine marls and limestones bearing richmolluscan faunas, which have a maximumof 2000 meters in the Cajamarca-Celendinarea but are only about 1000 meters thick inthe Cerro de Pasco-Pomachaca region. Theuppermost marine sediments are early San-tonian. They are, however, missing west ofthe continental divide.

4. The limestones and marls (Albian-Santonian) are succeeded, also withoutangular relationships, by thick, coarse, red-bed deposits (Chota formation), the lowerbeds of which, for reasons given below, arethought to be Campanian.

5. This sequence was strongly folded,probably during the late Senonian, and thencovered, with distinct angular relationships,by non-marine, coarse red beds (Pocobamba,Rimac formations) of Tertiary age.

This summary agrees with the generalizeddescriptions of the Colombian and Venezue-

lan Cretaceous given by Hedberg (1942, p.207) and Bucher (1952, p. 8).A single lithic classification cannot be

adopted in view of facies variations in anarea as large as the one under study. For thesake of convenience, the formational units aredescribed under four headings: (a) WesternMountain Front, (b) Central Western Andes,(c) Northern Western Andes, and (d)Marafi6n Valley. They reflect primarily thelocation of the type sections of the forma-tions under;description, but, to be sure, arenot strict stratigraphic provinces.

It has long been recognized that theCretaceous invertebrate faunas of northernSouth America have close Mediterranean(Atlantic or Tethyan) affinities. Because ofthese affinities, and because the early workwas done mainly by European stratigraphers,the South American Cretaceous has beenreferred to the Standard European Stages.These terms are well entrenched in the litera-ture and, moreover, they have almost uni-versal acceptance. The writer, after a re-valuation of the cephalopod faunas, decidedto follow this procedure, although having inmind the limitations of correlations halfwayacross the world.The marine portion of the system under

study, excellently developed in the Caja-marca-Celendfn area, has been divided into13 zones, and an effort has been made to usesingle ammonite species as zonal indices.They are fully discussed in a following sec-tion. Further research will determine if thesezones are also applicable to the rest ofnorthern South America.The faunal lists are arranged according to

taxonomic order. The data on the abundanceand the occurrence of the species are to befound in the description of the species and inthe stratigraphic sections.

WESTERN MOUNTAIN FRONT

CHIM(x SANDSTONEThis sandstone is here defined and named

from Banos de Chimu', a well-known hotspring and settlement in the upper part of the

Chicama Valley on the road from Trujillo toSayapullo. The river cuts a narrow, steep-walled gorge across this formation. The typesection was measured from a point 250

365


STAGES

TURONIAN

CENOMANIAN

ALBIAN

Upper

Middle

Lower

APTIAN

BARREMIANHAUTERIVIAN

VALANGINIAt N

UPPER JURASSIC

IZONES

COILOPOCERAS NEWELLI

COILOPOCERAS JENKSI

ACANTHOCERAS CHASCA

OXYTROPIDOCERAS CARBONARIUM

KNEMICERAS RAIMONDII

PARAHOPLITES NICHOLSONI

VALANGINITES BROGGII

CALLEJON DE LOW. CHICAMA TEMBLADERAHUAYLAS SECT. VALLEY SECT. SECTION

PARIATAMBO

CHULEC

PARIAHUANCA

CARHUAZ

SANTA

I

CHIMU

GOYLLARISQUISGA

CARHUAZ

SANTA

CHIMU

"CHICAMA BEDS"

FIG. 4. Cretaceous system in the western mountain front.

meters downstream from the hot springs to400 meters upstream from the same point.The Chimui sandstone comprises 685

meters of very thick-bedded, massive, hard,strongly cross-bedded, fine- to medium-grained, well-sorted, very clean, white to lightgray quartz-sandstone. The exposed sur-faces are mainly light reddish brown tolight gray. It contains in subordinate pro-portions (less than one-tenth) plant-bearing

carbonaceous shales and also beds of coalwhich in the Chicama area have been studiedin some detail by Stappenbeck (1929). In thetype section, a 1-meter thick bed of suban-thracitic coal is 200 meters above the base. Atthe top, there is a 30-meter bed of applegreen, hard, clayey, tuffaceous siltstone.There are six coal beds in Callacuyan, two ofwhich are being mined.The base of the quartz-sandstone sequence

366VOL. 108

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rests disconformably on the soft, dark gray toblack, varicolored shales, tuffs, and sand-stones of the "Chicama beds." The lithicbreak is very distinct and is conspicuouslyreflected in the topography (pl. 31, fig. 2).The upper boundary of the Chimu' sandstoneis above the last, massive, thick-beddedquartz-sandstone bed. It is also well shownin the topography, for the overlying shalesand limestones of the Santa formation, de-fined in this paper, are very soft, friable, andweather out very easily, so that the top of theChimui sandstone is almost always exposed(pl. 32, figs. 1, 2). As a whole, the Chimu'sandstone stands out in the topography,making up craggy ridges, conspicuous dipslopes, or deep gorges. If the beds have highdips, it makes tremendous cliffs. Stappenbeck(1929, p. 9) first recognized this formationand referred to it as the "lower coal-bearingquartzites of the Wealdian."The Chimfi sandstone has been observed

by the writer along the Cordillera Occidentalfrom the Jequetepeque River on the north toHuaraz on the south. Eastward, it is absentalong the Maranf6n River (Celendin andCrisnejas sections). Whether the disappear-ance is by overlap or erosion is not kInown,but both factors seem to be involved. Itswestern extensions and relationships are un-known.

The Chimui sandstone forms the core of theChimua, Cepo (pl. 32, fig. 1), Colmillo, Que-payoc, and Callacuyan anticlines in theupper Chicama Valley, and the core of theSanta anticline (pl. 32, fig. 2), in the Callej6nde Huaylas. It also outcrops repeatedly alongthe Pushca and Sihuas rivers, between theCordillera Blanca and the Marafi6n River.The Chimiu sandstone rests disconform-

ably on the marine Chicama beds from which.a Portlandian (upper Jurassic) fauna hasbeen described (Welter, 1913). A determinedsearch in the uppermost beds of the sequencefailed to produce any fossils, and thereforethey cannot be dated with certainty. How-ever, it is very likely that they are also Port-landian, as assumed by Stappenbeck (1929,p. 7) and Welter. Disconformably overlyingthe Chimui sandstone is the late ValanginianSanta formation. The age of the Chimu'sandstone, therefore, is within the post-Port-landian, pre-late Valanginian interval.

The Chinui sandstone has very regular bed-ding, cross-bedding of the angular type (pl.33, fig. 1), and contains carbonaceous shalesand allochtonous coal beds which seem to in-dicate subaqueous deposition. The sands arevery clean and mature and show a high de-gree of sorting; the grains are frosted. Theysuggest some previous wind work and deriva-tion from either a deeply weathered graniticterrain or, more likely, from an earlier sandysediment.The ChimAi sandstone was deposited under

conditions of tectonic quiescence, with noneighboring high lands.

SANTA FORMATIONStappenbeck (1929, p. 14) described the

"middle shales" or "Pallares shales" as agroup of shales with an average thickness of500 meters, rarely up to 1000 meters, in theupper Chicama Valley, overlying his "lowerquartzites of the Wealdian" (Chimui sand-stone). Fifty meters above the base, he men-tions a member of black limestone full ofParaglauconia strombiformis Schlotheim. Thepresent writer finds that this "limestone withParaglauconia" is dominantly marine and isseparated by an unconformity from theupper non-marine shales. Therefore, he pro-poses to divide the "Pallares shales" ofStappenbeck into two new formations: theSanta and the Carhuaz formations (fig. 15).Because Stappenbeck did not designate atype section for his "Pallares shales" and be-cause they are best exposed and developed inthe Callejon de Huaylas, the Carhuaz sec-tion (fig. 20), just northwest of Carhuaz, isselected as the type location of these two newformations (p1. 32, fig. 2).

In the Callej6n de Huaylas, betweenPariahuanca and Carhuaz, the Santa Riverflows through the axis of a south-plunginganticline. The core of this anticline is Chimdisandstone. Overlying this sandstone are 341meters of limestones and shales which are

here named the Santa formation. The typesection is on the eastern slope of Cerro Huall-hua, 6 kilometers northwest of Carhuaz, on

the western side of the Santa River, forwhich the formation is named.The Santa formation is largely of dark

gray, fossiliferous, medium-bedded, platy,concretionary limestone which is dolomitic in

1956 367


places and is interbedded with a few thinbeds of black, splintery shale and chert. Atthe top is a 15-meter thick bed (bed 5 of theCarhuaz section) of dark gray, thick-bedded,massive, platy, grayish-blue-weathering lime-stone which stands out prominently as a ledgealong the valley slope. Overlying this lime-stone are the softer shales of the Carhuazformation. At the base of the Santa forma-tion, there are soft, varicolored, finiely splint-ery shales which rest on the massive, ridge-forming, top ledge of the Chimui sandstone(pl. 32, fig. 2).Steinmann (1930, p. 111) studied this

formation in this area and referred to it asthe "lower limestones of the Barremian"(fig. 15).The known geographic distribution of the

Santa formation is similar to that of theChimui sandstone. In the upper ChicamaValley, this formation has in the lower part115 meters of Trigonia-bearing shales andsilts, and in the upper part, 65 meters ofbrown to black, yellowish-weathering lime-stone, including at the top a limestone intra-formational conglomerate which marks theupper boundary of the Santa formation.

In Callacuya6n, the formation is 284 metersthick and includes mostly fossiliferous shalesand silts; the limestones are reduced to theupper 35 meters. It was here mistaken byStappenbeck (1929, fig. 3) as belonging tothe Jurassic "Chicama beds." In Pomachaca,it is only 83 meters thick; the lower 25 metersare of sandstones and siltstones and theupper 58 meters are of black, grayish-black-weathering, medium-bedded, platy, hard,Paraglauconia-bearing limestone with fewcherty interbeds. This limestone becomesmore argillaceous towards the top. In allthese localities and in Sihuas, the Santaformation is thinner and less calcareous thanin the Callej6n de Huaylas area.The most common fossils in this formation

are Buchotrigonia gerthii Lisson, Bucho-trigonia flexicostata Fritzsche, Buchotrigoniainca Fritzsche, Paraglauconia studeri Vila-nova, and Paraglauconia strombiformis Schlo-theim. The species of Trigonia are moreabundant and dominant in the Callej6n deHuaylas area. Dietrich (1938, p. 99) has sug-gested that the irregularity of the ribbing ofthese species may be due to the influence offresh waters. The species of Paraglauconia, a

brackish-water gastropod genus, are moreabundant in the northern and eastern expo-sures of the Santa formation. The fauna isotherwise similar to that found in the lowestbeds of the overlying Carhuaz formation andwhich is dated as late Valanginian. On thestrength of this, it is considered that theSanta formation is Valanginian and notBarremian as thought by Steinmann.The Santa formation represents a change

from the non-marine conditions that pre-vailed during the deposition of the Chimu'sandstone to a shallow marine to brackish-water environment. It records a marine over-lap from the west. North and east of theCallej6n de Huaylas area, the Santa forma-tion becomes less calcareous, loses its marinefaunas, and becomes thinner. It would seemthat it was deposited in an embayment theeastern shore of which abutted againstMarafionia land, somewhere along the posi-tion of the present Marafo6n River, and thatit was also limited towards the north alongthe present Jequetepeque River.

CARHUAZ FORMATIONDisconformably overlying the Santa

formation are 1300 meters of non-marine tobrackish, varicolored shales designated hereas the Carhuaz formation. The type sectionwas measured on the western side of theSanta Valley, beginning at a point 3 kilo-meters northwest of the town of Carhuaz,for which the formation is named; it over-lies the type section of the Santa formation(Carhuaz section; fig. 20; pl. 32, fig. 2).Steinmann (1930, p. 112) referred to this

formation as the "intermediate beds of theBarremian," although in places he confusedit with the Chimu' sandstone. In the Santaanticline (Steinmann, 1930, fig. 124) he showsNeocomian sediments overlying youngerBarremian beds. The Carhuaz formationforms the upper part of Stappenbeck's(1929, p. 14) "middle shales" or "Pallaresshales," which he described in the upper Chi-cama Valley (fig. 15).

In the type section, the Carhuaz formationis dominantly of thin-bedded, soft, friable,brownish and purplish shales and silty shalesinterbedded with a few light gray to brown-ish, thin-bedded, and cross-bedded quartz-sandstones. Eighty meters above the base aretwo beds of gypsum, 5 meters thick each;

368 VOL. 108


they can be traced throughout the Callej6nde Huaylas. Between these gypsum beds andthe base of the formation are richly fossil-iferous, marine, gray limestones interbeddedwith shales. Above the gypsum the Carhuazbeds are largely of non-marine shales andquartz-sandstone with only occasional thinbeds of dark brownish fossiliferous marinelimestone. In the upper part, especially, arenumerous green and purple tuffs. The shalesin some places contain a rich fresh to brack-ish-water fauna with species of Cyrena andParaglkuconia. The lower boundary is placedat the top of the massive, very compact, andthick-bedded Pariahuanca limestone. As awhole, the Carhuaz formation is softer thanthe limiting formations.

In the Cajamarca and Chicama areas, theCarhuaz formation is composed of the sametype of very soft, friable, well-bedded, red-dish, purplish, and yellowish shale withParaglauconia and Cyrena, interbedded withwhite to brownish quartz-siltstone and cross-bedded quartz-sandstone. In these areas, nolimestones with marine fossils are present;there are plant-bearing carbonaceous shales.The formation in 794 meters thick in theChicama section; it overlies an unconformitymarked by limestone intraformational con-glomerate on top of the Santa formation. Itis succeeded by the Goyllarisquisga forma-tion.The Carhuaz formation, from the type

area, intertongues towards the east with thesandy Goyllarisquisga formation. In theCajamarca and Chicama areas, it grades intoand is also overlain by the Goyllarisquisga(fig. 8).From the lowest beds, in the type locality,

the following fossils were collected:Valanginites broggsi Liss6n, Buchotrigoniagerthii Liss6n, Buchotrigoniaflexicostata Fritz-sche, Buchotrigonia inca Fritzsche, Cucullaeagabrielis Leymerie, and several specificallyundeterminable olcostephanid ammonites.Oysters are found 400 meters above the base.Elsewhere, Cyrena huarasiensis Fritzsche,Paraglauconia studeri, and Paraglauconiastrombiformis are the most common fossils.The plant remains are similar to those of theChimu and Goyllarisquisga formations. Val-anginstes broggii indicates a late Valanginianor, less probably, an early Hauterivian age.The overlying Pariahuanca formation is con-

sidered early Albian. With these data, in thetype area, the Carhuaz formation is assignedto the late Valanginian-Aptian interval. Inthe Chicama and Cajamarca areas, where itis overlain by the Goyllarisquisga formation,it obviously represents the earlier part of thisspan.

After the deposition of the Santa forma-tion, there was a withdrawal of the sea.Marine sedimentation continued only on asmall scale in the Callej6n de Huaylas areafor a short time, at the end of which therewas restriction of marine conditions anddeposition of gypsum beds which were suc-ceeded by non-marine shales and sandstones.Occasionally, the sea would invade this area,leaving thin beds of fossiliferous limestone.

PARIAEUANcA LIMESTONEIn the Callej6n de Huaylas area, the Car-

huaz formation is overlain disconformablyby 95 meters of massive, ridge-forming,thick-bedded, fossiliferous, medium gray,light gray-weathering, strongly petroliferouslimestone which is named after the town ofPariahuanca, on the eastern side of theSanta River. The type section (Pariahuancasection) is 400 meters due north of Paria-huanca, on the north side of the stream thatflows near this village. The Pariahuancalimestone is exposed on both limbs of a tightsyncline parallel to the Santa anticline, themeasured section being on the eastern limbof the syncline. Steinmann studied thislocality as well as others along the Callej6nde Huaylas, and referred to the Pariahuancalimestone as the "Caprotina limestone"or as the "upper limestone of the Barremian"(fig. 15).The contact with the underlying softer,

dark purple and green shales and silty shalesof the Carhuaz formation is well marked andreflected in the topography. The upper bound-ary is marked by the end of the massive,medium gray limestones on which are restingthe soft, nodular, thin-bedded, brownishgray marls and limestones of the Chulecformation.Some beds of the Pariahuanca limestone

have abundant rudistid fragments, amongwhich Fritzsche (1924) identified Requieniaammonia Goldfuss and Agria blumenbachiStuder. In addition, there are miliolid for-aminifers, and on the weathered surfaces it is

1956 369

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYpossible to see sections of large gastropods(Nerinea) and pelecypods. From bed 4(Pariahuanca section) a single large, poorlypreserved specimen of Parahoplites sp. wascollected.On the basis of the rudistids, and consider-

ing the overlying Chulec formation as Aptian,Steinmann assigned the Pariahuanca lime-stone to the late Barremian. The presentwriter assigns it to the early Albian, based onthe following evidence:

1. It contains Parahoplites, an Aptian-early Albian ammonite genus.

2. It is overlain by the Chulec formationwhich is now considered to be, in this locality,early middle Albian (Knemiceras raimondiizone).

3. It is in the same stratigraphic position

as the early Albian (Parahoplites nicholsonizone) Inca formation of northern Peru.The Pariahuanca limestone has been

studied only in the Callej6n de Huaylasarea. Steinmann (1930) reports it in Hua-llanca, 50 kilometers southeast of the typesection. In Pomachaca, east of the CordilleraBlanca, it is absent by change of facies. It hasgraded into the marls and nodular argillace-ous limestones that compose the lower partof the Chulec formation in this locality.Northward, following the strike of the Andes,it is replaced, in the Chicama and Cajamarcaareas, by the Inca formation.The upper beds of the Carhuaz formation

show already the approach of marine condi-tions, and the Pariahuanca limestone signifiesthe full advance of a shallow sea.

CENTRAL WESTERN ANDESSeveral formations were described first by

McLaughlin (1924) in the central PeruvianAndes. The present writer did not visit thetype localities of these formations, but stud-ied them in Pomachaca, north of Cerro dePasco, and from there northward. Except forthe Jumasha formation, they extend withoutmajor changes as far north as Chota, thenorthernmost point studied by the writer.Farther north, information is wanting.

GOYLLARISQUISGA FORMTIONMcLaughlin (1924, p. 605) defined the

"thick formation of sandstones and shaleswith which the coal of the Peruvian Cordi-llera is associated" between the LiassicPucara limestone and the Chulec memberof the Machay limestones as the "Goyllaris-quisga-Jatunhuasi sandstone." He mentionedGoyllarisquisga, in central Peru, as the typearea. Recently, Jenks (1951, p. 211) hasappropriately proposed to emend the nameto "Goyllarisquisga formation" which is theterm that is used in this paper.

In the type area, these authors describethe formation as red shaly sandstone withassociated quartz pebble conglomerates rest-ing disconformably on the channeled Pucarilimestone. McLaughlin (1924, p. 605) says:"the rock is generally composed of whitequartz sands, medium grained for the most

part, but with some thin beds with quartz andchert pebbles coarse enough to allow therock to be considered a conglomerate. Thickbeds of red and black shale occur intercalatedwith the sandstones at several horizons.Basalt flows or diabase sills are also fairlycommon members of this formation."

J. V. Harrison, in his various publicationson the central Peruvian Andes, refers to thisformation (1943, p. 9) as the "Lower Cre-taceous Sandstone Series . . . beds of rusty-coloured sandstones [which] alternate withconglomerates, shales and sandstones carry-ing ironstone concretions." In the upperChicama Valley, already in the northernAndes, Stappenbeck (1929, p. 15) distin-guished this formation as the "upper quartz-ite with shales," which he named "Farratquartzite."

Recently, Tafur (1950, p. 15) defined inCajamarca the "Llacanora formation" in-cluding two members: the lower argillaceous(the upper part of Stappenbeck's Pallaresshales), described here as the Carhuaz forma-tion, and the upper "sandy and quartzitic"(Stappenbeck's Farrat quartzite), describedhere under the older and well-establishedname of Goyllarisquisga formation.

Outcrops of this formation extend through-out the Cordillera Occidental in both centraland northern Peru. Where the Crisnejas

370 VOL. 108

1BENAVIDES: CRETACEOUS SYSTEM IN PERU 371

so

STAGES ZONES POMACHACA-- SET

.,ON

CAMPANIAN

SANONIAN I LENTICERAS ALTAI

CONIACIAN SUCHICERAS BILOBATUM

TURONIAN

CENOMANIAN_oso _ 0mo

ALBIAN Middle

Lower

APTIAN_oom _ *_mmm

NEOCOMIAN

CHOTA

CELENDIN

a,-.-.. I_

JUMASHA

OXYTROPIDOCERAS CARBONARtUM PARIATAMBO...., _


I4FPARAHOPLITES NICHOLSONI

4

FIG. 5. Cretaceous system in the central Andes.

River discharges into the Maraft6n River (fig.19), it rests disconformably on the gentlychanneled Triassic Uliachfn formation (pl.31, fig. 1) and is 666 meters of white toreddish, coarse-grained, pebbly, cross-bed-ded, lenticular, medium- to thick-bedded,reddish-brown-weathering quartz-sandstone.The quartz grains are subrounded and moreor les well sorted. It is overlain disconforma-bly by marine shales and marls of the Crisne-jas formation, containing in the lowest beds

Parengonoceras pernodosum and other earlymedial Albian fossils.

Also in the Marafi6n Valley, in Balsas,east of Celendin (fig. 16), the Goyllarisquisgaformation disconformably overlies thick-bedded, medium gray limestones which arevery much like those described by Steinmann(1930, p. 68) in the Utcubamba Valley farthereast, and which he considered to be Liassic.In Balsas, at the base of the Goyllarisquisgaformation is a 40-meter thick basal conglome-

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rate composed of subrounded ill-assortedpebbles and cobbles up to 20 centimeters indiameter of limestone like that of the under-lying Liassic beds, embedded in a very

calcareous, chocolate-red, quartz-sandstonematrix. The bulk of the formation is a thick-bedded, white to gray, very clean, coarse-

grained to pebbly, yellowish-brown-weather-in quartz-sandstone with several thin car-

bonaceous shale interbeds. It is overlain bythe marls and shales of the Crisnejas forma-tion, containing in the lower beds species ofKnemiceras and Parengonoceras of earlyAlbian (Knemiceras raimondii zone) age.

This section is very similar to that describedby Kummel (1950, p. 259) for Leimibamba,60 kilometers farther east.Around Cajamarca (pl. 36, fig. 2), the

Goyllarisquisga formation lies disconform-ably on the Carhuaz formation; it is 578meters thick, the lower 400 meters beingalmost entirely of white to reddish white,medium- to thick-bedded, medium- to coarse-

grained, massive, ridge-forming, brown-weathering quartz-sandstone (pl. 34, figs. 1, 2).The upper 178 meters are the same type ofsandstone but interbedded with increasinglylarger proportions of purple, yellowish, andreddish, finely bedded shales which bearpoorly preserved plant remains. The top is

distinctly marked at the base of a limestonebasal conglomerate of the early Albian Incaformation, equivalent of the Pariahuancalimestone of the Callejon de Huaylas area.

The Cajamarca formation was also studiedin Chota (Lajas section), Hualgayoc (Hual-gayoc section), and in the upper ChicamaRiver (Sunchubamba section); in the lastplace, it is 469 meters thick. In all theselocalities, it has the same relationships andcharacteristics as in the Cajamarca section;it is between the Carhuaz and the Incaformations, and the rocks are less coarse

grained than in the sections along theMarafi6n River.Near the coast, in the lower part of the

Jequetepeque River (Tembladera section,fig. 18), only the upper 592 meters of theGoyllarisquisga formation are exposed: theyare of brownish and greenish, medium- tothick-bedded, fine- to medium-grained sand-stones interbedded with slaty carbonaceousshales. In the upper part are 25 meters ofthinly interbedded, brick-red quartz-siltstone

and shale which are then overlain by heavyledges of dark gray limestone which is as-sumed to be the equivalent of the Paria-huanca limestone and of the Inca formation.

In Chocofin, between San Pedro and Pa-casmayo on the Pacific coast, the Goyllaris-quisga formation is composed of white to yel-lowish brown siltstone and quartz-sandstoneoverlying disconformably a thick sequence ofdark purple and black volcanic agglomeratesand basaltic lava flows. These volcanic rockscannot be dated with the standard methods,but it is assumed, on a lithic basis, that theChimu' sandstone and the Santa formationare missing and that the volcanics are ofJurassic age.

Other extensive areas of outcrop of theGoyllarisquisga formation have been foundbetween Cajabamba and Huamachuco, andsouthward in the Sihuas and Pushca (Poma-chaca section) rivers; in the last locality, itis 732 meters thick.The Goyllarisquisga formation is a lithic

unit with coarser-grained rocks on the east andfiner-grained on the west. Along the MarafionRiver it is almost exclusively of quartz-sand-stone and pebbly sandstone. Westward, therocks become finer grained and intertonguewith the shales and quartz-siltstones of theCarhuaz formation (fig. 8). In the Callej6n deHuaylas area, the Goyllarisquisga is absentby change of facies into the Carhuaz. In thenorthern Andes, the change is not complete;the lower beds of the Goyllarisquisga inter-tongue with the Carhuaz formation and theupper beds overlie this formation.The Goyllarisquisga and the Carhuaz

formations lie on a regional unconformity.They rest on Triassic (Crisnejas section),lower Jurassic (Celendin, Utcubamba, Yauli,and Cerro de Pasco sections), upper Jurassic(Chocofin section), and on earlier Creta-ceous sediments (Sunchubamba, Pomachaca,Callacuyan, and Carhuaz sections).The Goyllarisquisga formation is overlain,

with transgressive relationships by the earlyAlbian Inca formation in the northernwestern Andes, by the medial Albian Crisne-jas formation along the Maraft6n River, andby the Chulec formation in the centralAndes. The last formation is earliest Albian-early medial Albian in Pomachaca, but else-where it is early medial Albian. In general,towards the east the Goyllarisquisga forma-

VOL. 108372


tion is covered by progressively youngermarine beds.The Goyllarisquisga formation has in

places coal beds and carbonaceous shales thatcarry plant remains similar to those of theearlier Chimu sandstone.The Goyllarisquisga and Carhuaz forma-

tions are almost entirely non-marine. In theCallej6n de Huaylas, marine tongues arepresent in the Carhuaz formation and indi-cate interfingering with marine sediments tobe expected farther west. They are certainlypresent in the Lima area, although theirstratigraphy is poorly known. Also, the pres-ence of volcanic rocks in the Carhuaz forma-tion in this area indicates that there werevolcanic sources towards the west. East-ward, Marafionia was a land of low relief andcoastal swamps. After the deposition of themarine to brackish Santa formation, the sea

withdrew and in places was restricted; anunconformity was developed and non-marinesedimentation was initiated. Gypsum bedsare found in the Santa Valley and intraforma-tional conglomerates in the upper Chicama

FIG. 6. Late Carhuaz (Aptian) lithofacies map,northern Peru.

Valley. Towards the east the Goyllarisquisgais found on channeled Triassic and Jurassicrocks. In its upper part, the Goyllarisquisgaformation is transgressive in nature; itsupper boundary moves in time, includingyounger beds as it moves eastward.The presence of quartz pebbles in the

Goyllarisquisga formation was interpreted byHarrison (1943, p. 31) as "evidences ofcorrugation not far away," but the presentwriter believes, instead, that the Goyllaris-quisga formation, as well as the underlyingChimui and Santa formations, was depositedunder quiet tectonic conditions, and thatthe quartz pebbles and sands had theirorigin in the metamorphic rocks exposed inthe core of Marafionia or in those of theBrazilian craton.Apparently the Amotape Mountains area

stood high during all this time, and theGoyllarisquisga equivalents are missingthere. Whether it stood high as islands or was

part of larger lands has as yet to be workedout.

CHULEC FORMATIONThe following is a translation of the

description of a section measured by Stein-mann (in Schlagintweit, 1912, p. 48) alongthe Oroya Railroad in the neighborhood ofOroya and Pariatambo in central Peru (seealso Steinmann, 1930, fig. 155)."TURONIAN (?) SENONIAN (?)12. Marl, sandy, crumbly, with yellowdolomite beds. Turonian (?) Cenoman-ian (?) Vraconian (?)

11. Limestone, marly, poor in fossils,bearing Ostrea and Gervillia at the base

. . . . . . . . . . . . . . . ca. 500 m.

VRACONIAN10. Limestone, dark, cherty .... . 509. Marl, black, with limestone beds . . 30-408. Limestone, dark, thick-bedded, with

Schloenbachia acutocarinata. 10-157. Beds with silicified fossils.1-156. Limestone, compact, dark.10LOWVER GAULT5. Limestone, marly, with fossils of the

lower Gault .5.0.".. . . . . . . . SO"The fossil fauna from this locality had been

made famous before by Gabb (1877), Stein-mann (1881), and Gerhardt (1897a).

It was McLaughlin (1924, p. 608), how-ever, who defined formally the Machayformation composed of the Chulec (unit 5

Aptian \

l:^,, Quartz-sandstone

~ Shale

LimestoneI

1956 373


of Steinmann's section) and Pariatambo(units 7 to 10 of the same section) members.As Steinmann pointed out (1930, p. 135), thelithic and faunal differences between thetwo members are very well marked, and hediscussed both "members" separately underthe headings of "Aptian" and "Albian,"respectively. In the present paper, the Chulecand Pariatambo members are given therank of formations, and Pariatambo nearOroya is considered as the type area.McLaughlin (1924, p. 608) described the

Chulec "member" as: "thin bedded, lightgray limestone, weathering white with minorbeds of sandy shale. It contains abundantfossils indicative of Aptian age," and lies be-tween the Goyllarisquisga and the Pariatam-bo formations.

This formation is extensively developedin the Cordillera Occidental of central andnorthern Peru. A section similar to thatdescribed by McLaughlin and Steinmann incentral Peru was studied by the presentwriter in Pomachaca, farther to the north,where, disconformably overlying the quartz-sandstones of the Goyllarisquisga formationand below the dark, bituminous limestonesand marls of the Pariatambo formation, are100 meters of very fossiliferous, light grayto light brownish gray marls and argillaceouslimestones, with a few massive interbeds ofdark gray limestone. From the lowest bedsParahoplites sp. was collected, and in themiddle and upper parts Douvitleiceras monileand several species of Knemiceras are abun-dant.West of Pomachaca, in the Callejon de

Huaylas area (Pariahuanca section, fig. 20),the Chulec formation has thinned down to 25meters of nodular, thin-bedded, yellowishmarls and marly limestones, with Douvil-leiceras monile. The thinning is due to con-vergence and also to change of facies of thelower part into the massive, dark gray, thick-bedded, rudistid-bearing Pariahuanca lime-stone.

Farther north, in Sihuas, this formation isrepresented by about 200 meters of veryfossiliferous, light yellowish and brownishgray soft marls and clayey limestones, thelower part being more argillaceous and, as awhole, the marls being more prevalent.Douvilleiceras monile was found in the lowest

beds and species of Knemiceras, Prolyeliliceras, Brancoceras, and Parengonoceras aredistributed all through the sequence.

In the upper Chicama Valley the Chulecformation is 250 meters of fossiliferous, lightgray marls interbedded with a few massivegray limestones containing Douvilkeicerasand Knemiceras. Again, in the Cajamarcaarea, it has the unusual thickness of 525meters; the lower part is of yellowish andbrownish, splintery, fossiliferous marls inter-bedded with very massive, thick beds offossiliferous, dark gray limestone. In themiddle part, there are thick beds of splintery,soft, friable, fossiliferous, brownish shaleinterbedded with massive beds of Exogyra-studded limestone. The upper part is of thin-bedded, somewhat nodular, chalky-weather-ing, wavy-bedded marls and limestones. Inthis locality, the Chulec formation discon-formably overlies the early Albian Incaformation and underlies the late medialAlbian Pariatambo formation (pl. 33, fig. 2).It was studied here by Tafur (1950, p. 21)who named it "Santa Ursula formation."The lower beds contain several species ofKnemiceras, Parengonoceras, Douvilleiceras,Lyelliceras, Prolyelliceras, and Protanisocerasand numerous species of echinoids, gastro-pods, and pelecypods. Sections with similarstratigraphic relations, lithology, and paleon-tology have been studied in Polloc (Pollocsection), Hualgayoc, where it is 363 metersthick, and in Lajas, where it is 504 metersthick.The Chulec formation becomes noticeably

more calcareous towards the west, and inTembladera, near Pacasmayo on the Pacificcoast, the marls and shales have disappearedand, instead, there are only thick-bedded,dark gray, poorly fossiliferous limestones.Eastward, the Chulec loses its limestone bedsand grades into the shales and marls of thelower part of the Crisnejas formation (Celen-din and Crisnejas sections).

In Pomachaca, where it lies directly onthe Goyllarisquisga formation, the Chuleccontains Parahoplites, an Aptian-lower Al-bian genus, in its lowest beds, and species ofKnemiceras, Douvilleiceras, and Prolyelliceras,guides for the early medial Albian, in themiddle and upper parts. Elsewhere, however,the Chulec formation rests either on the

VOL. 108374

BENAVIDES: CRETAC1EOUS SYSTEM IN PERU

Albian Pariahuanca limestone or on theequivalent Inca formation and contains onlyearly medial Albian fossils. Everywhere, theChulec is overlain by the late medial AlbianPariatambo formation. It is considered,therefore, that this formation began to bedeposited in the early Albian, but that inmost areas it is only early medial Albian.The following is a list of the most common

fossils of this formation:Cephalopoda

Protanisoceras blancheti (Pictet and Campiche)Douvilleiceras monile (Sowerby)Parengonoceras pernodosum (Sommermeier)Parengonoceras guadaloupaeforme (Sommer-

meier)Parengonoceras tetranodosum (Liss6n)Parengonoceras haasi, new speciesParengonoceras? champaraense, new speciesKnemiceras raimondii Liss6nKnemiceras raimondii pacificum, new subspeciesKnemiceras raimondii tardum, new subspeciesKnemiceras attenuatum HyattKnemiceras attenuatum spinosum (Sommer-

meier)Knemiceras syriacum (von Buch)Knemiceras gabbi HyattKnemiceras triangulare, new speciesKnemiceras ovale, new speciesKnemiceras? ziczag BreistrofferBrancoceras aegoceratoides SteinmannLyelliceras lyelli (Leymerie)

PelecypodaCucullaea brevis GerhardtCucullaea gerhardti OlssonModiolus tnutissus OlssonNeithea morrisi Pictet and RenevierExogyra aquila BrogniartExogyra minos CoquandExogyra boussingaulti d'OrbignyMyopholas peruviana OlssonYaadia hondaana (Lea)Buchotrigonia abrupta (von Buch) (=B. hum-

boldti von Buch, B. coquandi Liss6n, and B.orbignyi Liss6n)

Pterotrigonia tocasimaana (Lea) (=P. subcrenu-lata d'Orbigny)

Cardita subparallela GerhardtAstarte debilidens GerhardtProtocardium elongatum GerhardtAnatina silinensis Richards

EchinoideaBothriopygus compressus GabbEchinobrissus subqguadratus d'OrbignyHolectyPus (Coenholectypus) planatus numis-

malis (Gabb)Phymosoma texanum Roemer

The Chulec formation is included withinthe zone of Knemiceras raimondii.

PARIATAMBO FORMATIONThe Pariatambo "member" was defined

by McLaughlin with type section nearOroya. In the present paper, it is raised to therank of formation. Lithically the Pariatamboformation is of fossiliferous, platy, slabby,black, strongly bituminous marl and lime-stone, with some intercalations of chert andwith large, discoidal, limestone concretions.In the type area, it is about 120 meters thick,rests disconformably on the early medialAlbian Chulec formation, and is overlain bythe Jumasha formation, also defined by Mc-Laughlin.A similar section was studied by the

present writer in Pomachaca, east of Huari.Resting on the Chulec formation are 208meters of black, brownish-weathering, medi-um-bedded, platy, concretionary, stronglybituminous marls and limestones overlain bythe massive, hard, dense, thick-bedded dolo-mites and limestones of the Jumasha forma-tion. The lower boundary is marked by thesudden appearance of the black, bituminousmarls. Analogous sections have been studiedin Pariahuanca and near Sihuas, although inthese two places the upper beds and theoverlying rocks have not been seen.

In northern Peru, it has been studied inthe upper Chicama Valley (Sunchubamba andHuaycot sections) where it is 204 meters ofblack, laminated, fissile, concretionary, bitu-minous, and calcareous shale interbeddedwith platy, bituminous limestone, resting onthe marls of the Chulec formation. The upperboundary, however, is not so sharp as it is incentral Peru, for the Pariatambo formationgrades quickly into the nodular, thick-bedded limestones and marls of the Yuma-gual formation. The same relations are pres-ent in the Cajamarca area, where it is 135meters of very argillaceous, still stronglybituminous limestone, which, on weathering,gives a chalky appearance. It was studiedhere by Tafur (1950, p. 26) who named it the"Yacu-Ushco formation." In Chota (Lajassection) it is 261 meters of very calcareous,massive, dense, black limestone. A similarsection is found in Hualgayoc (pi. 35, fig. 1).

It is also present in the Amotape Moun-

1956 375


FIG. 7. Pariatambo (middle of medial Albian)lithofacies map, northern Peru.

tains, in northwestern Peru (Olsson, 1934),where it is known by the local name ofMuerto limestone.Towards the east, before reaching the

Marafion River, the Pariatambo formationloses its bitumen content and grades intothe yellowish and brownish limestones andmarls of the upper part of the Crisnejasformation (fig. 8). In central Peru, Harrison(1943) does not find it east of Tarma.Everywhere it is richly fossiliferous. The

fossils are found especially in the large,discoidal concretions of dark, bituminouslimestone (pl. 35, fig. 2) and are difficult toextract.The most abundant fossils are:

CephalopodaDesmoceras latidorsatum (Michelin)Oxytropidoceras carbonarium (Gabb)Oxytropidoceras douglasi KnechtelVenezoliceras venezolanum (Stieler)Venezoliceras harrisoni, new speciesDipoloceras sp.Brancoceras aegoceratides SteinmannLyelliceras lyelli (Leymerie) (d'Orbigny)

Lyelliceras pseudolyelli (Parona and Bonarelli)Lyelliceras ulrichi KnechtelPelecypoda

Inoceramus concentricus ParkerInoceramus salomoni d'OrbignyAnomia sp.

Fish scales

Locally other mollusks are found. On thebasis of these fossils, the Pariatambo canbe assigned confidently to the middle of themedial Albian. It belongs to the zone ofOxytropidoceras carbonacrium.The Pariatambo formation is one of themost extensive and more uniform lithic unitsin the western Peruvian Andes. It representsthe culmination of the marine overlap thatbegan sometime during the Aptian. Eventhe Amotape Mountains, which stood beforeas lands, were covered by the PariatamboSea.The shallow marine conditions in which the

limestones and marls of the Chulec formationwere laid changed to a deeper, quieter en-vironment which was very favorable for theaccumulation and preservation of quantitiesof organic matter.

During Pariatambo time, marine waterscovered Marafnonia and apparently reachedthe eastern geosyncline. West of the positionof the present Marafi6n River, the waterswere deeper than towards the east.

JUTMASHA FORMATIONThe Jumasha formation was defined by

McLaughlin (1924, p. 609) who gave as atype section "the cliffs above Jumasha, onLake Punrum, in Central Peru." He indi-cated that the formation is a "uniform, lightgray limestone, generally more massivelybedded than the Machay beds . . v restsconformably on them ... and ... is over-lain by red shales and sandstones of probablyTertiary age." Also, he adds, "an extensivefauna has been described and the formationis correlated with the Senonian of Europe."The present writer has studied this

formation in Pomachaca, where it is 800meters of very massive, thick-bedded, lightorange-brown to yellowish brown and graydolomites and limestones which weatherdark yellowish brown to brownish gray. It isoverlain at this locality by shales and marls ofthe lower Senonian Celendfn formation, to

376 VOL. 108

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be described in the following pages. Generallythe formation is very poor in fossils. How-ever, a fortunate find was made in the lowerbeds of the Jumasha formation in Poma-chaca, where Lyelliceras ulrichi Knechtel andOxytropidoceras douglasi Knechtel were col-lected. These fossils are also found in theunderlying Pariatambo formation. Also, es-pecially in the upper part, the limestonescarry Foraminifera. This formation, there-fore, as already stated by Steinmann (inSchlagintweit, 1912, p. 48, and in Steinmann,1930, p. 155), represents the latest medialAlbian-Turonian interval which in northernPeru is represented by the Pulluicana andQuillquifian groups and by the Cajamarcaformation. Inasmuch as no distinctive breakshave been found, it is likely that the Jumashaformation represents fairly continuous sedi-mentation during that time. It was depositedprobably under deeper waters than those ofthe same time in northern Peru.

K\ FIG. 9. Isopachous map of the Infra-YumagualSLIMA (Neocomian-middle Albian) Cretaceous in north-NORTHERN jW ern Peru.

NORTHERN WESTERN ANDES

The Cretaceous sediments of the westernAndes in northern Peru (between Chota andHuamachuco) have an aggregate total thick-ness of 5000 meters. The lower third is domi-nantly of non-marine sediments, whereas theupper two-thirds is of very fossiliferous,calcareous rocks (fig. 10).

Several sections were studied in detail inthis area, the most important being the"Cajamarca section" (fig. 17; pl. 36, fig. 2),studied also by Tafur (1950), which is takenas a standard section of reference. This sec-tion exposes 3600 meters, has most of theunits in good outcrops, and offers the bestpossibilities of control. It lacks the lower partof the Cretaceous column, which was studiedbest in the upper Chicama Valley, as well as

the uppermost strata of this system (Celendinand Chota formations), exposed best in

Celendfn.Except for the Inca formation, all the

formations to the top of the Pariatambo are

the same in northern and central Peru, and

are described above. After Pariatambo time,however, the stratigraphic behavior in north-ern Peru is markedly different from that al-ready described for central Peru, for thepost-Pariatambo sequence in northern Peruis much thicker, its sediments are morefossiliferous, and they reveal more variableconditions of deposition. All the post-Pariatambo formations except the topmostCelendin and Chota formations have theirtype localities as designated by Tafur inthe Cajamarca section.

INCA FORMATION

This formation takes its name from Bafnosdel Inca, a famous hot spring 6 kilometerseast of Cajamarca. The type section is be-tween Kilometers 7 and 8 of the automobileroad from Cajamarca to Celendin, and ispart of the "Cajamarca section" (pl. 33,fig. 2). The Inca formation is 90 meters ofinterbedded brownish gray, brown-weather-ing, o6litic, arenaceous, and ferruginous lime-

378 VOL. 108


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stone and yellowish and greenish brown,finely splintery, fossiliferous shale, with sub-ordinate amounts of quartz-sandstone andsiltstone, lying between the Goyllarisquisgaand the Chulec formations. The whole forma-tion is conspicuously ferruginous and, ifdeeply weathered and leached, it has distinctbright yellow and red colors. At the base,there is an intraformational conglomeratecomposed of fragments of massive, darkbrownish gray, arenaceous limestone in aferruginous, argillaceous, silty, oolitic lime-stone matrix.Steinmann (1930, p. 119) referred to this

formation in his discussion of the Peruvian"Aptian," and similarly, Stappenbeck dis-cussed it as "unit 5" or "upper shales" of hisAptian sequence. Tafur (1950) has also stu-died this formation and named it "CapasRojas" in the belief that it is of continentalorigin.The lower boundary is placed at the base of

this intraformational conglomerate whichlies disconformably on the non-marine shalesand sandstones of the Goyllarisquisga forma-tion. The upper boundary is placed at thebase of a very distinct ridge-forming ledgeof dark gray, bluish-black-weathering, fossil-iferous limestone that belongs to the Chulecformation.

In the upper reaches of the Chicama andJequetepeque rivers (Sunchubamba andHuaycot sections) the Inca formation isabout 150 meters thick. The limestones are

arenaceous, bluish gray, and weather darkbrownish to yellowish; if leached out, theyleave excellent internal molds of pelecypods.The interbedded sandstones are very fer-ruginous; the shales are friable, yellowish andreddish, and yield a rich molluscan fauna inwhich trigonias are prevalent. The Incaformation has also been studied in the Chotaarea (Lajas section) where it is representedby dark gray, odlitic, arenaceous limestone(calcarenite) which weathers to a character-istic rusty, brownish yellow color. Theselimestones contain spatangoid echinoids,trigonias, exogyroids, and echinoid spicules.They are interbedded with laminated, soft,friable shales bearing small spherical concre-

tions of iron oxide and wvith dirty, ferruginousquartz-sandstones. The whole formation is

more calcareous than in the Cajamarca orChicama areas. It is slightly over 109 metersthick.At the junction of the Cajamarca and

Condebamba rivers (Tamberia section), theInca formation rests disconformably on theshales and sands of the Goyllarisquisgaformation, the contact being more or lessgradational. It is 71 meters thick, mainly ofred-purple to greenish shale and quartz-sandstone and a few ferruginous limestoneswhich are packed with fossil mollusks.The Inca formation is the basal deposit of

the marine Albian transgression. Towardsthe east, it grades into the upper part of theGoyllarisquisga formation by loss of thecalcareous and argillaceous beds. Along theMarafion River (Celendin and Crisnejas sec-tions), the Goyllarisquisga is overlain directlyby the Crisnejas formation which has earlymedial Albian fossils at its base. Westward,the Inca, as well as the overlying Chulecformation, becomes more calcareous andgrades into massive, thick-bedded, unniamedlimestones that lie on the Goyllarisquisgaformation (Tembladera section). The Incaformation has the stratigraphic position ofthe Pariahuanca limestone of the Callej 6n deHuaylas area.The Inca formation is richly fossiliferous.

The following fossils are found in it:CephalopodaDesmoceras chimuense, new speciesParahoplites nicholsoni, new speciesParahoplites quilla, new speciesParahoplites inti, new speciesKnemiceras ollonense (Gabb)

POecypoqdaijjEi,6arca gerhardti OlssonCucullaea brevis d'OrbignyPterotrigonia tocaimaana (Lea) (=P. subcrenu-

lata d'Orbigny)Yaadia hondaana (Lea) vBuchotrigonia abrupta (von Buch)Ptychomia robinaldina d'Orbigny (=P. lissoniiSommermeier)

Corbis (Sphaera) corrugata SowerbyEchinoidea

Enallaster Peruanus (Gabb)Arthropoda (unidentified)The species of Parahoplites have early Al-bian affinities. On this basis, and because the

overlying Chulec formation is medial Albian,

VOL. 108380


the Inca has been assigned to the earlyAlbian. It is part of the zone of Parahoplitesnicholsoni.The Inca formation was deposited under

shallow marine conditions. The abundance ofindividuals and the diversity of species andthe presence of Lingula and of crabs indicatea near-shore environment.

PULLUICANA GROUP

The term "Pulluicana group" was givenby Tafur (1950, p. 29) to embrace both thePariatambo formation (called Yacu-Ushcoby him) and that part of the succeedingsequence which has nodular, gray limestonesand marls. He divided these nodular lime-stones and marls into the Yumagual forma-tion below and the Mujarruin above. Becauseof the existence of an important unconform-ity on top of the Pariatambo formation, andbecause this formation represents the culmi-nation of the Albian transgression, the presentwriter excludes the Pariatambo formationfrom the Pulluicana group (fig. 15).The group was named after Pulluicana, a

small village 7 kilometers northeast ofCajamarca. The type locality is within theCajamarca section.As a whole, the Pulluicana group is

characterized by gray, light gray-weatheringlimestones and marls. The lower part (Yuma-gual formation) is more argillaceous and siltythan the upper one (Mujarrnun formation),and includes beds of quartz-sandstone andsiltstone. The limestones and marls arepeculiarly nodular, lumpy, or at least wavy-bedded (pl. 37, fig. 1), There are also somemassive beds and throughout the group,especially in the more argillaceous and marlybeds, are strata packed with exogyroids,oysters, and inocerami. Ammonites are veryrare.The Pulluicana group has been observed

along the Cordillera Occidental from Huama-chuco on the south to Chota on the north, andundoubtedly it continues farther north.

YUMAGUAL FORMATIONTafur (1950, p. 29) named this formation

after Cerro Yumagual, southwest of Caja-marca, although the type section is in theCajamarca standard of reference.

A summary of the type section is:YUMAGUAL FORMATION METERS3. Limestones, very argillaceous, nod-

ular, with interbeds of light brown-ish gray marl. Especially in the lowerpart, some beds are very close to beingcoquinas of Exogyra mermeti Coquand.In the upper part, Paraturrilites lewesi-ensis and Sharpeiceras occidentale arefound ....... 140

2. Limestone, light to medium gray, com-pact, nodular, thick-bedded. Some bedsare filled with Ostrea scyphax and Ino-ceramus sp. At the base there is a chertyconcretionary limestone . . . . . . . 214

1. Marl and silty marl, nodular, brown-ish yellow to light brownish gray, chalkyin places, with few beds of massive,nodular, dark gray limestone, and withsome beds of yellowish, cross-beddedquartz-sandstone. It has Ostrea scyphaxand other pelecypods. The lowest bedsinclude strongly bituminous, platy lime-stones which contain Oxytropidocerascarbonarium.... . 142

TOTAL, YUMAGUAL FORMATION: 496 METERS

The lower boundary is at the top of a ridge-forming, medium-bedded, platy, grayishblack, silty limestone with th'in interbeds ofchert which in this locality is the last unit ofthe Pariatambo formation. The upper bound-ary is where the soft, friable, nodular marlsand limestones of the Yumagual give way tothe massive, thick-bedded limestones anddolomites of the Mujarridn formation.

Similar sections have been studied inEncanada (Polloc section), Hualgayoc, andChota (Lajas section), being 538, 760, and627 meters thick, respectively.

In the type section, two fossil zones arerecognized within the Yumagual formation.The lower zone is marked by Ostrea scyphax;from the lowest beds Oxytropidoceras carbon-arium has been collected. The upper zone ischaracterized by Exogyra mermeti and theammonites Paraturrilites lewesiensis andSharpeiceras occidentaJe. Oxytropidocerascarbonarium is a species of the middle of themedial Albian, abundant in the underlyingPariatambo formation, whereas Paraturriliteslewesiensis and Shapeiceras occidentale are

early Cenomanian. On this basis, the Yuma-gual formation is assigned to the interval

1956 381


FIG. 11. Yumagual (late Albian-early Ceno-manian) lithofacies map, northern Peru.

late medial Albian-early Cenomanian. Incentral Peru, its time equivalent must bewithin the Jumasha formation.

Southeast of Cajamarca, the Yumagualformation becomes less calcareous, morecoarsely clastic, and changes facies into theRosa formation which contains non-marinered beds (fig. 11).

After the deposition of the Pariatamboformation, there was shallowing of the seas,and Marafionia emerged. In the Cajamarcaarea, shallow-water marls and limestoneswere deposited, and occasional quartz-silt-stones from the southwest interfingered in thesequence. There was abundant benthoniclife; ammonites were scarce.

MUJARRXIN FORMATIONThis formation takes its name from Cerro

Mujarn-n, northeast of Cajamarca. The typelocality is in the Cajamarca section. It com-

prises 370 meters of light to medium gray

nodular limestones and marls lying between

the Yumagual formation and the Quill-quinan group. The present writer divides itinto two members.CHORO MEMBER: It includes 300 meters of

thick-bedded, light gray to medium gray,massive, dolomitic (in places), slightly nodu-lar, wavy-bedded limestone interbedded withsubordinate amounts of nodular marls and afew quartz-siltstones. All through the se-quence, Exogyra cf. ponderosdi Steinmann(non Exogyra ponderosa Roemer) is veryabundant, and in the upper part Exogyraolisiponensis makes its first appearance. Ascompared with the other formations, thewant of ammonites is striking. This memberis very resistant to erosion.The Choro member grades from the type

section into more calcareous beds on the eastand south and into more argillaceous units to-wards the west. In the Chota area (Lajas sec-tion) it is 211 meters thick, very argillaceousand very similar to the underlying Yumagualformation; the specimens of E. cf. ponderosaweather out easily from the argillaceoussediments and are found lying around ingreat numbers. In Hualgayoc it is 194 metersthick and contains chert nodules.CULEBRA MEMBER: It comprises 70 meters

of light gray, chalky-weathering, nodular,very argillaceous marls and limestones muchless resistant and calcareous than the under-lying Choro member. It is succeeded by theRomiron formation of the Quillquifian group.The marl beds are crowded with .Exogyraafricana Lamarck, Exogyra olisiponensisSharpe, Exogyra polygona von Buch, Neitheatenousklensis Coquand, Orthopsis titicacanaCooke, and a few specifically undeterminableacanthoceratid ammonites. The upperboundary is a coarsely nodular surface onwhich lie the soft shales and marls of theRomiron formation.

Similar sections have been studied inEncafiada (Polloc section), where it is 86meters thick and particularly well exposed;in Hualgayoc, where it is 68 meters thick; andin Lajas, where it is 76 meters thick. East-ward it becomes more calcareous and thick-bedded, and in the Crisnejas section it can-not be differentiated from the underlyingChoro member.The Mujarruin formation is Cenomanian,

lying between the late Albian-early Ceno-

382 VOL. 108


manian Yumagual formation and the lateCenomanian Romir6n formation.Most of the fossils that Steinmann listed

in his discussion of the Peruvian Cenomanianwere collected from the Culebra member inthe Pampa de la Culebra, northeast of Caja-marca.

QUILLQUINAN GROUPDisconformably overlying the gray lime-

stones and marls of the Mujarrun formationof the Pulluicana group is a series of richlyfossiliferous marls and shales which havebeen defined as the Quilliquifian formationwithin the Otuzco group (Tafur, 1950, p. 33).In the present paper, the Quillquifian forma-tion is raised to the rank of group comprisingthe new formations Romiron and Cofnor, andthe term Otuzco group is restricted to theoverlying sequence (fig. 15). The type localityis within the Cajamarca section.As a whole the Quillquifan group consists

of very soft shales and marls interbeddedwith few limestones which are rusty yellowishbrown in the lower part (Romiron formation)and bluish gray in the upper one (CoAorformation). The rocks are so friable and soft,as compared with the overlying marls andlimestones of the Otuzco group or the under-lying marls and limestones of the Mujarrniformation, that the Quillquinlan group usu-ally forms topographic saddles or troughscovered with soil. In the type locality, forinstance, it is necessary to move along thestrike to find good exposures and preserve thecontinuity of the section.

Stappenbeck (1929, p. 19) studied thisgroup in Huacraruco, south of Cajamarca,and collected from it some fossils, amongwhich Steinmann identified the Turoniangenus Vascoceras. Later, Steinmann (1930,p. 146) tentatively described this group underthe heading of "Turonian" and gave a goodsection which he had observed in Huafiam-bra, between Celendin and Sendamal. Tafur(1950) assigned this group to the Coniacian.The present writer considers within this

group two new formations: Romir6n andCofior.

ROMIR6N FORMATIONThis name is given to the 50 meters of

yellowish and yellowish brown shales and

marls which disconformably overlie theCulebra formation. They are interbeddedwith very few and thin, peculiarly rusty,yellowish brown, detrital, highly fossiliferouslimestone beds. The formation is also charac-terized by the extraordinary abundance offossils, especially of Exogyra olisiponensisSharpe, which in places makes true coquinas.The lower boundary is at the coarselynodular surface at the top of the Mujarrfinformation. The upper boundary is at thebase of the first massive bed of bluish graylimestone of the Cofior formation. The termwas taken from Cerro Romir6n, 8 kilometersnortheast of Cajamarca.The best exposutes of the Romir6n forma-

tion are along the Cajamarca to Celendfnautomobile road, between Kilometers 29 and30, on both limbs of the Sangal syncline (pl.36, fig. 1), where it is 50 meters thick and hasthe same features as in the standard section.It is 72 meters thick in Hualgayoc and 162meters thick in Lajas. In these two places theRomir6n is very argillaceous, and there arebeds of coquinla of Exogyra olisiponensisSharpe. In 1802, Humboldt collected Exogyrapolygona from the outcrops of this formationin Montan, near Lajas. In Celendin, theRomir6n formation is 71 meters thick andalso extraordinarily fossiliferous, but theexogyras are exceeded in numbers of individ-uals by several species of cephalopods. Alongthe Marafi6n River, in the Crisnejas section,it is only 45 meters thick, very calcareous,with a striking scarcity of fossils as comparedwith the sections towards the west, and isoverlain directly by the Cajamarca forma-tion. It is also present in the upper ChicamaValley, but no thickness nor details can begiven because it is covered with soil and vege-tation. Southward exposures are not known.The fossils collected from this formation

are:Cephalopoda

Lissoiniceras mermeti (Coquand)Forbesiceras sp.Acanthoceras chasca, new speciesAcanthoceras sangalense, new speciesAcanthoceras pollocense, new speciesNeolobites kummeli, new species

PelecypodaMytilus sp.Neithea alatus von Buch

1956 383


Neithea aeguicostata LamarckNeithea tenoukiensis CoquandPlicatula reynesi CoquandPlicatula gurgitis Pictet and RouxPlicatula auressensis CoquandOstrea rouvilki CoquandExogyra olisiponensis SharpeExogyra olisiponensis duplex PaulckeExogyra polygona von BuchCardita doumeti PeronCoquandia itabica SeguenzaCorbula sp.

EchinoideaOrthopsis titicacana Cooke

This fauna indicates late Cenomanian. TheRomir6n formation is considered within theAcanthoceras chasca zone.The lithologies and the extraordinary

abundance of fossils suggest very shallowwater environment of deposition.

CONiOR FoRMATIONThe Coflor formation is named after Cerro

Coflor, 8 kilometers northeast of Cajamarca.The Coflor formation, as well as the Romir6n,is exposed in a belt at the northern foot of theCerros Cofior and Romiron. The type is inthe Cajamarca section and is 90 meters ofbluish gray marl interbedded with dark graylimestone beds overlying the Romiron forma-tion. The lower boundary is at the base of thefirst massive bed of dark gray limestone over-lying the yellow marls and shales of theRomir6n formation. The upper boundary is

at the top of the marls and the introductionof the continuous sequence of lithographic,massive, thick-bedded, dark gray limestoneof the Cajamarca formation. The limestonesof the Cofior formation are very similar tothose of the overlying Cajamarca formation,although usually they are more argillaceous.The marl is bluish and light gray and is some-what nodular. The Cofor formation is more

calcareous and less fossiliferous than theunderlying Romir6n formation; it lacks therusty, yellowish brown, coquinoid limestonesof the latter.

Together with the Romiron formation, theConlor is excellently exposed along theCajamarca to Celend!n road, in the Sangalsyncline, near Encafiada (pl. 36, fig. 1), wherea prominent massive unit of dark gray lime-

stone 48 meters thick is overlain by 100 metersof marl and fossiliferous shale. In Hualgayoc,the Cofior is 90 meters thick, including in thelower part 27 meters of light gray limestonewith very few marl interbeds, which is over-lain by nodular bluish marls. Farther west,in Lajas, the formation is about 200 metersthick, noticeably more argillaceous, and withfewer and thinner beds of massive gray lime-stone than in the sections of Cajamarca,Polloc, or Hualgayoc. In Tembladera (fig.18), near the Pacific coast, the Quillquifhangroup is so argillaceous throughout that thetwo formations Romiron and Coior cannotbe differentiated, although the faunal differ-ences carry on. Towards the east, in theCrisnejas section, the Cofior is no longerpresent; apparently, it has become so calcare-ous and thick-bedded as to become the lowerpart of the Cajamarca formation.The Cofior formation contains the follow-

ing fossils:CephalopodaMammites nodosoides afer Pervinqui6rePseudoaspidoceras reesidei, new speciesTkomasitesfischeri, new speciesHoplitoides inca, new species

PelecypodaInoceramus labiatus SchlotheimInoceramus sp.Plicatula gurgitis CoquandPlicatula reynesi CoquandCorbula peruana Gabb

EchinoideaHemiaster fourneli DeshayesThe ammonites are early Turonian.The conditions of deposition were similar

to those under which the Romiron was laid.The Cofior records the deepening of waters,with diminution of faunas and increase incalcareous materials, changing from theshales of the Romir6n into the lithographiclimestones of the overlying Cajamarca forma-tion.

OTUZCO GROUPDisconformably overlying the Quillquinan

group, Tafur (1950, p. 35) defined the"Otuzco formation," which is here raised tothe rank of group including two new forma-tions: Cajamarca (Steinmann's Actaeonellalimestone) and Celendin (Steinmann's "marls

VOL. 108384


and light colored limestones with the richfauna of Otuzco, Cajamarca"; Steinmann,1930). Tafur's Otuzco group is suppressed(fig. 15).

CAJAMARCA FORMATIONOne of the most conspicuous, uniform, and

extensively spread lithic units in northernPeru is the Cajamarca formation, the lime-stones and marls lying disconformably onthe Coior formation and below the Celendinformation. It is named after the town ofCajamarca, in northern Peru, near which isthe standard section of reference for most ofthe Peruvian Cretaceous; the type is in thissection, between Cerro Mujarrun and Que-brada Otuzco.Three types of lithologies are conspicuous

constitutents of the Cajamarca formation:A. Limestone, dark gray to brownish and

bluish gray, dense, lithographic, massive,thick-bedded, slabby, bearing Foraminiferaand large gastropods. It produces a character-istic lapiez, karstic topography and weatherslight bluish gray.

B. Limestone, medium gray, made ofcomminuted shell debris, thick-bedded, mas-sive, slightly less resistant than the precedingtype, whitish-weathering.

C. Marl, bluish or greenish white, nodular,containing in the more shaly and argillaceousparts a varied molluscan fauna.The first type of lithology is dominant, and

in places it seems to be the only one present.The lower boundary is at the base of thecontinuous sequence of massive, thick-bedded, blue-gray limestones that rest onthe soft marls and argillaceous limestones ofthe Cofior formation. The upper boundary ismore distinct, for it is at the top of the mas-sive limestones and base of the yellowish,soft, friable, richly fossiliferous shales of theCelendin formation. The Cajamarca forma-tion stands out in the topography of northernPeru in prominent ridges and peaks.

In the standard section, the Cajamarcaformation is 528 meters thick; 200 metersbelow the top is a 15-meter bed of shale andmarl from which Coilopoceras newelli, Card-ium lissoni Brtiggen, Inoceramus peruanusBriiggen, Hemiaster fourneli Deshayes, andCyphosoma peruanum Briiggen were col-

lected. This thin bed of very fossiliferousshale has been found also in the Polloc,Hualgayoc, and Bambamarca sections. Inthe first locality, the formation is 720 meters Xthick and excellently exposed. It is 540meters thick in Hualgayoc (pl. 37, fig. 2),and 316 meters thick in Celendin. In Lajas(pl. 38, fig. 1), it is only 211 meters thick;the upper part has been cut by an unconform-ity above which are coarse clastics of theChota formation (fig. 12). In Crisnejas, alongthe Marafi6n River, it is around 500 metersthick, has taken a dark yellowish brown color,and rests directly on the Romiron formation;apparently it includes in its lower part thetime equivalents of the Cofior formation.

Farther south, it has been studied inSanta Clara, between Sihuas and theMaraion River, where it is about 800 metersof dark bluish gray, thick-bedded limestonewith very few marly beds, and making verydistinct ridges in the high Andes. Probablyit rests disconformably on the Rosa forma-tion; the contact could not be seen, and thereis possibility of some structural complica-tion. It is suspected that the Cajamarcaformation in this locality includes the timeequivalents of the Mujarrin, Romiron, andCoior formations. It is overlain by theCelendin formation.

Finally, going farther south, the formationtakes on a pale yellowish brown or darkyellowish orange color, acquires dolomitic bedsin increasing proportions, loses its argil-laceous beds, and grades into the Jumashaformation of central Peru. At the same timeit incorporates earlier beds. In Pomachacathe change into the Jumasha has been com-plete; it can no longer be distinguished asCajamarca formation.The limestones of the Cajamarca formation

contain scanty remains of Foraminifera andgastropods among which Steinmann identi-fied Actaeonella sp. In the few shaly, argil-laceous beds is a rich fauna characterized byCoilopoceras newelli, new species, Inoceramusperuanus Brtiggen, Cyphosoma peruanum andHemiaster fourneli Deshayes.

Steinmann assigned a Senonian age to thisformation, although he also hinted that thelower part might be Turonian. The presentwriter prefers to assign it, in the standard

1956 38S


section, to the late Turonian on the followingdata:

A. It contains Coilopoceras, elsewhere aTuronian genus.

B. It underlies the Celendin formationwhich is earliest Coniacian (Buckiceras bilo-batum zone) in its lowest beds.

Southward, it gains earlier beds and gradesinto the late Albian-Turonian Jumashaformation of central Peru.The Cajamarca formation represents the

last important deepening of the seas in thenorthern Peruvian Andes. The sea apparentlytransgressed from the south and west, de-positing fine, lithographic limestones. Itseems that Marafionia was inactive.

CELENDfN FORMATIONThis formation is named after the town of

Celendfn, northeast of Cajamarca. The typesection (part of the Celendfi section; fig. 16)is in the Melendez Creek, 6 kilometers north-west of Celendin, 500 meters north ofHacienda La Quinua. The massive, thick-bedded, blue-gray limestones of the Caja-marca formation are succeeded disconform-ably by 255 meters of very soft, yellow, fri-able, richly fossiliferous shales interbeddedwith few limestones which are defined as theCelendin formation. The upper boundary isat the top of the yellow marine shales and thebase of the coarse, non-marine red sandstoneof the Chota formation. Eighty-nine metersabove the base is a 60-meter bed of lightbrownish gray, massive, somewhat nodularlimestone which bears alveolinellid Foraminif-era. Below this limestone, the shales con-tain a rich molluscan fauna in which theammonite genera Buchiceras, Heterotissotia,Tissotia, and Barroisiceras are prevalent.Above the limestone, the shales contain adiff-erent and less diversified fauna charac-terized by the genera Lenticeras, Texanites,Desmophyllites, and Tissotia.

In the Cajamarca section only part of theformation is exposed in the badly deformedtrough of the Otuzco synclinle. Steinmann(1930, p. 156) referred to it as the "upperhorizon" of his "Senonian" and described asmall part of the section upside down, for hedid not realize the local overturning of thebeds.

In Bambamarca, the Celendfn formation

is 345 meters thick and very well exposed.The lower contact with the Cajamarca for-mation is well marked, and the top is overlainby over 500 meters of red-bed conglomeratesof the Chota formation. Most of the forma-tion is of shales and marls. The distributionof fossils is as in the type section. Fartherwest, in the Lajas section, the Celendinformation is cut out by an unconformity; theChota conglomerates lie directly on theCajamarca formation. In the Polloc section,the lower part of the Celendin formation iswell exposed and also very fossiliferous.Southward, in the Rupac River west ofSihuas (Santa Clara section), it is 591 metersthick and is more calcareous and less fossil-iferous than in northern Peru. The fossilsfound are those that characterize the upperpart of the formation in the Cajamarca andCelendln areas. It is overlain by a thick se-quence of red shales and sandstones of theChota formation. Steinmann (1930) studiedthis locality and referred to part of theCelendin formation as the "yellow, veryfossiliferous, sandy marls of Santa Clara."

Farther south, it has been found along thePushca River (Uchupata section) overlyingmassive, thick-bedded limestones and dolo-mites of the Jumasha formation. It is 100meters thick, poorly fossiliferous, light green-ish gray, somewhat silty, and is overlaindisconformably by gypsiferous red beds ofthe Chota formation.

It is likely that it is represented also in thecentral Andes. Steinmann's "unit 12" in hisOroya section is in the right stratigraphicposition, and his description corresponds tothat of the Celendfn formation. He also de-scribed a similar section in La Quinua, nearCerro de Pasco (Steinmann, 1930, p. 156).Moreover, Paulcke (1903) described anearly Senonian fauna from this last localityand from Charata, between Oroya and Tarma.The Celendin formation is found only in a

few places preserved in the troughs of syn-clines or in downfaulted blocks. It resemblesthe Romiron formation strikingly in thelithologies, topographic expression, and inthe abundance of fossils, although the lastare entirely different. It is the most fossilifer-ous formation in northern Peru.Two fossil zones are considered within the

Celendin formation: the zone of Buchiceras

386 VOL. 108

1BENAVIDES: CRETACEOUS SYSTEM IN PERU

bilobatum (beds 69 to 72 of the type section)and the zone of Lenticeras baltai (bed 73 of thetype section).The zone of Buchiceras bilobatum contains:

CephalopodaBarroisiceras (Barroisiceras) haberfellneri von

HauerBarroisiceras (Barroisiceras) kayi, new speciesBarroisiceras (Solgerites) brancoi SolgerBarroisiceras (Forresteria) basseae, new speciesBarroisiceras (Forresteria) allisaudi Boale, Le-

moine, and Th6veninTissotia hedbergi, new speciesHeterotissotia peroni LissonHeterotissotia bucheri, new speciesBfuchiceras bilobatum Hyatt

PelecypodaCucu4laea maresi CoquandModiola sp.Inoceramus aequivalvis BruggenInoceramus peruanus BriiggenJPlicatulopecten ferryi CoquandSpondylus striatus SowerbyLima (Plagiostoma) grenieri CoquandOstrea (Lopha) nicaisei CoquandOstrea sp.Ostrea bravoi BruiggenRoudairia intermedia BruiggenCardiuim pulchrum BriiggenPholadomya elongata MuensterPholadomya quinuana Neumann

EchinoideaCyphosoma schlagintweiti BruggenSeveral species of the group of Hemiaster four-

neli Deshayes

In addition it contains a great number ofspecies of gastropods, bryozoans, and a fewvertebrate bones. In terms of numbers ofindividuals, the echinoids are dominant.The zone of Lenticeras baltai contains the

following:Cephalopoda

Bostrychoceras sp.Desmophyllites gaudama (Forbes)Texanites hourcqi CollignonTexanites sp.Tissotia steinmanni Liss6nTissotiafourneli (Bayle)Tissotia halli KnechtelLenticeras baltai Liss6nLenticeras lissoni Knechtel

PelecypodaInoceramus sp.Lima sp.Ostrea (Phola) nicassei CoquandRoudairia intermedeia Briggen

Cardium pulchrum BriiggenEchinoidea

Hemiaster fourneli DeshayesGoniopygus hemicidariformis BruiggenGoniopygus superbus Cotteau and Gauthier

The zone of Buchsiceras bilobatum is Conia-cian; the zone of Lenticeras balta4 is earlySantonian. The Celendin formation, there-fore, is Coniacian-early Santonian.The Celendin formation was deposited

under shallow waters. The upper boundarymarks the end of marine sedimentation in thenorthern Andes; the succeeding deposits arecoarse, red-bed clastics that came from thewest.

CHOTA FORMATIONThe marine Cretaceous sequence is dis-

conformably succeeded by non-marine, red-bed coarse clastics which Broggi (1942, p. 10)has named the Chota formation. He observedit in Lajas, west of Chota, where it is severalhundred meters, largely of very coarse con-glomerate and sandstone lying on the thick-bedded limestones of the Turonian Caja-marca formation; the conglomerates containcobbles of quartzite and plutonic rocks.

In Bambamarca, east of Chota, the con-glomerates are less coarse, at least 500 metersthick, and lie on the soft shales of the lowerSenonian Celendin formation. Farther east,in Celendfn, the Chota formation is of redquartz-sandstone and shale with only a fewthin conglomerates of quartz pebbles. InSanta Clara (pl. 38, fig. 2), near the Marafi6nRiver, it is almost exclusively of fine redsandstones and shales over 1000 meters thickand lying disconformably on the Celendinformation, the contact being indistinct. InUchupata, east of Huari, it is of gypsiferousred-bed shales and sandstones over 200meters thick.The lower boundary of the Chota forma-

tion is an unconformity which increases inmagnitude westward (fig. 12). The upperboundary is always either cut by structuresor covered with distinct angular relation-ships by younger non-marine and volcanicrocks. The Chota formation resembles thePocobamba formation of the central Andesas well as the ill-defined and heterogeneousRimac terrane but is distinguishable because itlies disconformably on the marine Cretaceous

19S6 387

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYsLAJAS BAMBA MARCAf~~~~~~~~~~~~~~

-O O-0 OR.0 N

FIG. 12. Turonlian-Senonian in the western Peruvrian geosynclinle.

sequence; it is older than those formations.The rocks of the Chota formation become

coarser grained towards the west. This, andthe fact that an unconformity at its base in-.creases in the same direction, indicate awestern source, probably an orogenicallyactive land.

Along the coast, an orogeny took place inConiacian-Santonian time. In Paita, Cam-panian sediments overlie "complexly foldedcristalline and metamorphic rocks" (Olsson,1944, p. 15). It is likely that Turonian rocksare involved in this basement, for in Tem-bladera, near Pacasmayo, the Neocomian-

Turonian (probably Jurassic-Turonian) se-quence is normal and has the same relation-ships and characteristics as the sequence inthe western Andes. Thick-bedded blue-graylimestones of the Turonian Cajamarca forma-tion are the top beds of the Tembladera sec-tion (fig. 18).The present writer thinks that the Chota

clastics are the flysch deposits of the orogenythat affected the coastal area, and that theyare of Santonian-Campanian age. Later,they were strongly folded and covered bycoarse clastics like the Pocobamba formationof central Peru.

MARARON VALLEYSections studied along the Maraion River,

between Celendin on the north and the PushcaRiver on the south, show some striking dif-ferences from those of the Cordillera Occi-dental, especially in the pre-Mujarruin stra-tigraphy. The best exposed section is alongthe lower part of the C.risnejas River as itdischarges into the Marafi6n River at lati-tude 070 21' S. Two new formations are con-sidered here (fig. 13).

CRISNEJAS FORMATIONThis formation is named after the Crisnejas

River. The type section (fig. 19) was meas-ured on the south side of this river, betweenthe Marafi6n River and the small settlementof Santa Rosa. Disconformably lying on thequartz-sandstones of the Goyllarisquisgaformation and below the sandstones of theRosa formation, defined in the followingpages, are 365 meters of shales, marls, andlimestones which are grouped under theterm Crisnejas formation. The lower part has

greenish and yellowish, splintery, soft, thin-bedded, fossiliferous, calcareous shales inter-bedded with thin units of light gray marl andlimestone. The sequence becomes morecalcareous upward, and the upper part is oflight yellowish brown to tan, massive, thick-bedded limestone. From the lowest bedsParengonoceras pernodosum, Ostrea dieneriBlackenhorn, and several echinoids were col-lected. The upper limestones are character-ized by Oxytropidoceras carbonarium andTnoceramus concentricus Parker. The lowerboundary is very sharply defined at the topof the massive quartz-sandstone of theGoyllarisquisga formation. The upper bound-ary is also very distinct (pl. 39, fig. 1), for itis a deeply weathered and channeled dis-conformity below the quartz-sandstones ofthe Rosa formation.Along the Marari6n River, near Quiches

(Santo Cristo Bridge section), there is asimilar but thicker section. The lower 220meters are bluish gray, splintery shale inter-

VOL. 108388


STAGES ZONES CRISNEJAS% _SECTION

TURONIAN

CENOMANIAN

Middle


COILOPOCERAS JENSII I

ACANTHOCERAS CHASCA

CAJAMARCA

ROMIRON

EXOGYRA AFRICANA

_ MUJARRUNEXOGYRA CF. E. PONDEROSA

OXYTROPIDOCERAS CARBONARIUM


-4 'Lower

APTIAN

NEOCOMIAN

UPPER JURASSIC

LOWER JURASSIC_ . _ _

TRIASSIC

ROSA

CRISNEJAS

GOYLLARISOUISGA

I~

LIRCIULIACHIN

. aJ.

FIG. 13. Cretaceous system in the Maraft6n Valley.

bedded with light greenish and bluish, thin-bedded, somewhat nodular, fossiliferous marl.The upper 240 meters are medium gray togreenish, brownish-weathering, massive,thick-bedded limestone underlying the clasticred beds of the Rosa formation.

It has also been studied in Celendin, whereoverlying disconformably on the Goyllaris-quisga formation are 430 meters of yellowishand brownish gray marl and shale inter-bedded with dark gray, rusty-weathering

limestone in the lower part and with lightgray, somewhat nodular limestone in theupper part. The lower beds contain numer-ous species of Knemiceras, Parengonoceras,and Protanisoceras as well as many echinoidsand pelecypods. The upper beds are charac-terized by Lyelliceras pseudolyelli Parona andBonarelli and several echinoids.

In general, the fauna present in the lowerpart of this formation is the same as that inthe Chulec (zone of Knemiceras raimondii)

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19S6 389

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formation in the Cordillera Occidental,whereas the fauna of the upper beds is adistinct Pariatambo fauna (zone ofOxytropidoceras carbonarium). The Crisnejasformation is therefore medial Albian, andtime equivalent of the Chulec and Paria-tambo formations. As the lower beds becomemore calcareous, they grade into the Chulecformation, and as the upper limestones be-come finer and bituminous, they grade intothe black, strongly bituminous marls andlimestones of the Pariatambo formation (fig.8).

ROSA FORMATIONThe type section was measured beginning

500 meters downstream from Santa Rosa, asmall settlement in the lower part of theCrisnejas River. In the lower part, it hasterrigenous sediments: quartz-sandstones,red-bed sandstones, and conglomerates whichbecome finer and calcareous upward. A sum-mary of the type section is given here:

METERS3. Sandstone, shale, and marl, finely inter-

bedded, becoming more calcareous andmassive towards the top. The marl isfossiliferous, brown, massive; the shaleis greenish and whitish gray; the sand-stone is reddish white, laminated a 187

2. Deep cherry-red sandstone, siltstone,and conglomerate. Thesandstone is soft,cross-bedded; the conglomerate is ofperfectly rounded, faceted quartz peb-bles ranging between 1 cm. and 20 cm.in diameter; the matrix is red, friable(pl. 39, fig. 2) . . . . . . . . . . . 317

1. Sandstone, calcareous, coarse-grained,medium- to thick-bedded, slabby,brownish white, interbedded with afew shale and limestone beds . . . . 95The lower contact with the underlying

limestones of the Crisnejas formation is asharp unconformity (pl. 39, fig. 1). The upperboundary is also distinct, for the upper thin-bedded, soft, friable marls and limestones ofthe Rosa formation are succeeded by massive,thick-bedded limestones of the Mujarrunformation.

zO1The Cretaceous sequence in northern Peru

has been divided into 13 zones (fig. 14).A zone is "a group of beds characterized by

The Rosa formation has been found atseveral points along the Marafi6n River,namely, in Chagual east of Huamachuco,and in Quiches east of Sihuas. In this lastplace (Santo Cristo Bridge section), it is150 meters of red-bed shale and sandstonewith a few interbeds of gypsum in the lowerpart.

Farther south, along the Pushca River(Uchupata and Pomachaca sections), theRosa formation is absent, apparently bychange of facies, and the thick-bedded lime-stones and dolomites of the Jumasha forma-tion directly overlie the Pariatambo forma-tion. Also, north of the Crisnejas River inCelendin, the Rosa formation is absent;limestones of the Pulluicana group lie directlyon the Crisnejas formation. Towards thewest, the Rosa formation interfingers quicklywith silts, marls, and limestones of the Yuma-gual formation of the Cajamarca area.The Rosa formation for the most part is of

non-marine origin. After the deposition of theCrisnejas formation, i.e., at the end ofPariatambo time, the Marafo6n geanticlinewas raised, exposing to erosion not only thepreceding Cretaceous sediments but probablypre-Mesozoic rocks. An erosion surface wasdeveloped. Non-marine deposition was ini-tiated, and gypsum evaporites were depositedin the margins of the retreating sea. The red-bed sandstones and conglomerates wereapparently subjected to some wind workprior to deposition. The upper strata of theRosa formation records the gradual returnof marine conditions which became then fullyprevalent.

In the type section, the Rosa formationoverlies the Crisnejas formation, which ismedial Albian, and is overlain by the medialCenomanian MujarrnT formation. It repre-sents, therefore, the late Albian-early Ceno-manian interval and is the time stratigraphicequivalent of the Yumagual formation. It isalso assumed, on the basis of stratigraphicposition, that it grades into the lower partof the Jumasha formation of central Peru.

IESan assemblage of organisms, one of which ischosen as the index species and gives its nameto the unit although it need not be confined

390 VOL. 108

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391


to this unit or found in every part of it"(Hedberg, 1941, p. 2206; see also Arkell,1933, p. 19; 1946, p. 10). In accordance withstandard use in Mesozoic stratigraphy, exceptfor three zones, single ammonite specieshave been given as zonal indices.

After the ammonites, the species ofInoceramus, Exogyra, and Ostrea are the mostuseful fossils. They are commonly found ingreat numbers; their ranges, however, arefar greater than those of the ammonitespecies. Gastropods are also very common,but occur usually in steinkerns and cannot bestudied well; apparently, they also have verylong vertical ranges. The echinoids followthe pelecypods in numerical abundance,but their ranges are even greater than thoseof the pelecypods. Bryozoans are rarely foundand have been given only cursory examina-tion. Foraminifera are common in the lime-stones but would have to be studied in thinsections.The non-marine part of the sequence is

rich in fossil plants which do not seem to haveparticular stratigraphic value.The Peruvian Cretaceous faunas belong to

a single faunal province which extendedthrough northern South America and parts ofBrazil. It is suggested, therefore, that thesezones may be found applicable throughoutthis faunal realm.

ZoNE op Valanginites broggiiThe Santa limestone and the lowest beds

of the Carhuaz formation are characterizedby Valanginites broggii associated with otherspecifically unidentifiable species of olco-stephanid ammonites and the followingpelecypods:

Buchotrigoniaflexicostata (Fritzsche)Buchotrigomia inca (Fritzsche)Buchotrigonia gertkii (Liss6n) (= Trigonia

mathewsi Richards)Cucullwea gabridlis LeymerieCyrena huarasensis Fritzsche

The brackish to fresh-water gastropodsParaglauconwia studeri Vilanova var. Peruana(Fritzsche) and Paraglauconia strombiformis(Schlotheim) are also found in this zone,associated usually with the last-namedpelecypod and rarely with the trigonias.Dietrich (1938, p. 99) thinks that the ir-

regularity of the ribbing of B. flexicostata andB. inca is due to the influence of fresh waters.The genus Valanginites is distributed

through northern South America (Spath,1924, p. 80), Mexico (Imlay, 1940, p. 135),and Europe. It is significant that it has notbeen reported from the well-studied Neocom-ian sections of Argentina. Both Kilian (1920,p. 12) and Imlay (1940, p. 135) state thatValanginites, although it is found both in theHauterivian and in the Valanginian, is mostcharacteristic of the last stage. Spath (1924,p. 80) referred to the " Valanginites beds"of Colomrbia and correlated them with the"Hoplitidan age" of the English Valanginian.The present writer has been unable to findany other reference to these ColombianValkngsnites. On these grounds this zone istentatively assigned to the upper Valangin-ian.

ZONE OF Parahoplites nicholsoniThe Inca formation of northern Peru

and the Pariahuanca limestone of theCallejon de Huaylas area are marked byParahoplites nicholsoni, new species, assoc-iated with large, specifically unidentifiableparahoplitid ammonites and the followingspecies:CephalopodaDesmoceras chimuense, new speciesParahoplites quilla, new speciesParahoplites inti, new speciesKnemiceras oUlonense (Gabb)

PelecypodaTrigonoarca gerhardti OlssonC-ucullaea brevis d'Orbigny.Pterotrigonia tocaimaana (Lea) (= P. sub-

crenulata d'Orbigny)Yaadia hondaana (Lea)Buchotrigonia abruPta (von Buch)Buchotrigonia robinaldina d'Orbigny (= B. Iis-

soni Sommermeier)Corbis (Sphaera) corrugata Sowerby

EchinoideaEnallaster per-uanus (Gabb)The genus Parahoplites appears in the

lower Aptian and reaches its maximum devel-opment in the middle and upper Aptian,although ". . . the last parahoplitids stilloccur at the top of the Lower Albian tardefur-cata zone with early Douvilleiceras" (Spath,1930, p. 60). The genus Knemiceras reachesits maximum diversification in the next zone,

392 VOL. 108

Bi6ENAVIDES: CRETACEOUS SYSTEM IN PERU

MCLAUGHLIN STAPPENBEKf STEINMANN TAFUR THIS PAPER1924 1927 199 1950 j

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PALLARES Sh.

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t~OWER QUArTZATEOF THE WEALDLAN

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IFiG. 15. Development of the stratigraphic terminology of the Cretaceous system in northern

Peru. McLaughlin's column includes only those names that have bearing on the stratigraphy of

northern Peru. The numbers in Stappenbeck's column are those he used to designate his strati-

graphic units.

assigned to the lower middle Albian, and is

usually considered to be an Albian genus.The present writer knows no authenticatedoccurrence of this genus in Aptian deposits.The fauna of this zone has close affinities

with Colombian faunas described by Riedel(1937-1938) which include a large number ofspecies of Parahoplites. Unfortunately, hisdescriptions lack stratigraphic details. It alsohas close relationships with the controversial

7-I- a

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-I.

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1956 393


so-called Clansayes fauna of France whichcorresponds to the Acanthoplites nodosoco-statum zone of England. The Clansayes faunais considered by many as transitional be-tween the Albian and the Aptian. Accordingto Breistroffer (1947) it constitutes the upperpart of the Aptian stage, but Spath (1923-1943, vol. 1, p. 311) considers it to be thelowest Albian. Scott (1940, p. 1029) hasdescribed from Texas a large fauna, includingParahoplites and Knemiceras which mark hisSonneratia trinitensis zone, which he cor-relates with the lower and middle Albian.The species of Parahoplites contained in

this zone seem to have affinites with speciesof the Albian genera Hypacanthoplites andRhytidoplites. In addition, the presence of theAlbian genus Knemiceras and the fact thatthe overlying zone of Knemiceras raimondiiis early medial Albian seem to indicate thatthe zone of Parahoplites nicholsoni is earlyAlbian.

ZoNE OF Knemiceras raimondiiThe Chulec formation and the lower part

of the Crisnejas formation are characterizedby Knemiceras raimondii. It is associatedwith the following species:Cephalopoda

Prokanisoceras blancheti (Pictet and Campiche)DouviUeiceras monile (Sowerby)Parengonoceras Pernodosum (Sommermeier)Parengonoceras guak&oupaeforme (Sommer-

meier)Parengonoceras tetranodosum (Liss6n)Parengonoceras haasi, new speciesParengonoceras? champaraense, new speciesKnemiceras raimondii pacificum, new sub-

speciesKnemiceras raimondii tardum, new subspeciesKnemiceras attenuatum HyattKnemiceras attenuatum spinosum (Sommer-

meier)Knetniceras syriacum (von Buch)Knemniras gabbi HyattZKemiceras triangulare, new speciesKnemiceras ovak, new speciesKnemiceras? siczag BreistrofferBrancoceras aegoceratoides SteinmannProlyiUCieras peruvianum SpathLyeliceras Iyell (Leymerie) (d'Orbigny)elecypodaCucukaea brevis GerhardtCuculaea gerhardti Olsson

Modiolus mutissus OlssonNeithea morrisi Pictet and RenevierExogyra aquila BrogniartExogyra minos CoquandExogyra boussingualti d'OrbignyMyopholas peruviana OlssonYaadia hondaana (Lea)Buchotrigonia abrupta (von Buch) (=B. hum-

boldti von Buch, B. coquandi Liss6n, and B.orbignyi Liss6n)

Pterotrigonia tocaimaana (Lea) (=P. subcrenu-lata d'Orbigny)

Cardita subparallela GerhardtAstarte debilidens GerhardtProtocardium elongatum GerhardtAnatina silinensis Richards

EchinoideaBothriopygus compressus GabbEchinobrissus subquadratus d'OrbignyEnallaster peruanus GabbHolectypus (Coenholectypus) planatus numis-

malis (Gabb)Phymosoma texanum Roemer

One of the most significant species in thislist is Douvilleiceras monile, distributed innorthern South America (Riedel, 1937-1938), Europe (Spath, 1923-1943, vol. 1, p.72; Breistroffer, 1947, p. 40), North Africa,Madagascar (Collignon, 1949), and India(Spath, 1930). In England, it is the index ofthe subzone of Douvilleiceras monile, whichmarks, according to Spath, the base of themiddle Albian, and according to Breistroffer(1947) the top of the lower Albian. Pro-tanisoceras blancheti is also another importantammonite confined (Spath, 1930, p. 51) to thezone of Douvilleiceras mammillatum of Eng-land.The genus Knemiceras has also a wide dis-

tribution. It is known in northern SouthAmerica (Breistroffer, 1952, p. 2633),Texas (Scott, 1940), North Africa (Mah-moud, 1952), the Middle East (Bass6, 1937,1940), India, and Borneo, usually in beds con-sidered medial Albian. In Peru, this genusseems to have reached its maximum diversi-fication in this zone. Only one species, Knem*-ceras ollonense, is found in the underlying zoneof Parahoplites nicholsoni, and another spe-cies, Knemiceras ovale, is known in the over-lying zone of Oxytropidoceras carbonarium.

Parengonoceras ebrayi de Loriol, the closestrelative of the Peruvian species of Parengono-

VOL. 108394


ceras, is found in the lower middle Albian("Protohoplitien" of Breistroffer, 1947, p.40; or the Douvilleiceras mammillatum zoneof Spath) of Europe.

Lyelliceras Iyelli and Brancoceras aego-ceratoides are rarely found in this zone butattain great abundance in the next zone ofOxytropidoceras carbonarium.The present writer follows Spath's zona-

tion of the Albian and regards the zone ofKnemiceras razmond-i as at the base of themiddle Albian.

ZONE OF Oxytropidoceras carbonariumThe Pariatambo formation, the upper part

of the Crisnejas formation, and the Muertolimestone of northwestern Peru are char-acterized by Oxytropidoceras carbonarium(Gabb) and the following:Cephalopoda

Desmoceras latidorsatum (Michelin)Knemiceras ovale, new speciesOxytropidoceras peruvianum (von Buch)Oxytropidoceras douglasi KnechtelVenesoliccras venezolanum (Stieler)Venesoiceras harrisoni, new speciesDipoloceras sp.Brancoceras aegoceratoides SteinmannLyelliceras lycdl (Leymerie) (d'Orbigny)Lyeliceras pseudolyelli (Parona and Bonarelli)Lyelliceras ulrichi Knechtel

PelecypodaInoceramus concentricus ParkerInoceramus salomoni d'OrbignyAnomia sp.Astarte debilidens GerhardtExogyra minos CoquandCorbula raimondii Gabb

EchinoideaEnallaster peruanus Gabb

The species of ammonites and inoceramiare particularly abundant in the black, well-bedded, petroliferous marls and limestones ofthe Pariatambo formation; they become veryscarce in the non-bituminous marls of theCrisnejas formation. Knemiceras has notbeen found in the otherwise richly fossilif-erous black facies.The genus Oxytropidoceras is distributed

through northern South America (Riedel,1937-1938; Breistroffer, 1952), Brazil,Mexico (Imlay, 1944, p. 1095), the GulfCoast (Adkins, 1928), the western interior of

the United States (Cobban and Reeside,1952, p. 1016), Europe, Madagascar, andIndia. According to Spath (1923-1943, vol. 2,table 3, p. 706) it ranges from the top of thezone of Douvillekceras mammillatum throughmost of the middle Albian (zones of Hoplitesdentatus and of Euhoplites lautus). Breistrof-fer (1947), who excludes the zone of Douvil-leiceras mammillatum from the middle Albian,refers to the middle Albian as the "Oxytro-pidoceratien."

According to Spath (1923-1943, vol. 2, p.706), the genus Venezoliceras is limited to theHoplites dentatus zone, and he says (1930, p.50) that in England, Lyelliceras seems to beconfined to the benettianus subzone (lowerpart of the Hoplites dentatus zone). In France,Breistroffer (1947, pp. 40, 42) reports Lyel-liceras of the Iyelli group in the "Douvil-leiceratien" and the "Oxytropidoceratien."

It seems that the zone of Oxytropidocerascarbonarium can be correlated with the zoneof Hoplites dentatus of Europe, approxi-mately the middle of the medial Albian, forin the overlying zone of Euhoplites lktusneither Lyelliceras nor Venezoliceras has beenfound. It can also be correlated with the zoneof Oxytropidoceras, at the top of the Fred-ericksburg, in the United States.

ZONE OF Ostrea (Lopha) scyphaxThe lower part of the Yumagual formation

and of the Rosa formation is characterized byOstrea scyphax Coquand, which sometimesforms great accumulations. It is usually as-sociated with thick-shelled, unidentified spe-cies of Inoceramus. In this zone, ammonitesare notably scarce; only one specimen ofEngonoceras sp. indet. was obtained from it.Echinoids (Enallaster peruanus Gabb andBothriopygus compressus Gabb) are locallyplentiful.

Ostrea scyphax is a North African speciesusually referred to the Cenomanian. Thegenus Engonoceras, although over 100 yearsold and very abundant in the Gulf Coast,Europe, North Africa, and the Middle East,has not been reported in South America. Itranges through the Albian and the Ceno-manian (Bass6, 1940, p. 436) but seems toachieve its maximum diversification duringthe late Albian and the early Cenomanian. In

1956 395


England, it is rarely found in the dispar zone(upper Albian) and has been described as a"straggler from the south" (Spath, 1923-1943, vol. 2, p. 703).The data to compare this zone with the

European or North American zones are poor.However, because the succeeding zone ofParaturrilites lewesiensis is early Cenomanianand because Engonoceras is especially abun-dant in the late Albian, the zone of Ostreascyphax is considered late Albian, but it mayeven include part of the medial Albian. Theunconformity at the base of this zone repre-sents, probably, the late medial Albian.

ZONE OF Paraturrslites lewesiensssThe upper part of the Yumagual formation

is characterized by Paraturrilites lewesiensisSpath. It is associated with:

Sharpeiceras occidentale, new speciesExogyra mermeti Coquand (=Exogyra dicera-

tina Paulcke)

The last species, in places, builds large ac-cumulations; ammonites are, as a rule,scarce.

Paraturrilites lewesiensis Spath, a Britishspecies, is found in the Schloenbachia varianszone of the English Cenomanian (Wright andWright, 1951, p. 17). Sharpeiceras laticla-vium, a species closely related to S. occiden-tale, is also found in this zone. On the strengthof this, the zone of Paraturrilites kewesiensisis considered lower Cenomanian and cor-related with the Schloenbachia varians zoneof the British sequence. Spath (1926, p. 429)has said: "Turrilites are thus as useful as theammonites for zoning the lower three-quarters of the Cenomanian."

ZONE OF Exogyra CF. Exogyra ponderosaThe Choro member of the Mujarruin for-

mation is marked by Exogyra cf. Exogyraponderosa Steinmann (1930, fig. 224)-nonExogyra ponderosaRoemer,a Senonian species.The zone, containing this exogyroid in greatabundance, has not yielded a single am-monite specimen. In the upper part, Exogyraolisiponensis makes its first appearance. Itlies between the early Cenomanian zone ofParaturrilites lewesiensis and the early lateCenomanian zone of Exogyra africana.

ZONE OF Exogyra africanaThe Culebra member of the Mujarr-dn

formation is characterized by great numbersof indivriduals of Exogyra africana Coquand(=Exogyra peruana Paulcke). It also con-tains Exogyra olisiponensis Sharpe, Exogyrasp., Neithea alatus von Buch, Neithea tenouk-lensis Coquand, Orthopsis titicacana Cooke,and specifically unidentifiable acanthoceratidammonites. The genus Acanthoceras marksthe upper Cenomanian (Acanthoceratan ageof the European stratigraphers). Because thenext zone is latest Cenomanian, the zone ofExogyra africana is assigned to the early lateCenomanian.

ZONE OF Acanthoceras chascaThis zone comprises the Romiron forma-

tion and, wherever undifferentiated, thelower part of the Quilliquifnan group. Proba-bly it is included within the Jumasha forma-tion. It is marked by Acanthoceras chasca,new species, and the following:Cephalopoda

Lissoniceras mermeti (Coquand)Forbesiceras sp.Acanthoceras sangalense, new speciesAcanthoceras pollocense, new speciesNeolobites kummeli, new species

PelecypodaMytilus sp.Neithea alatus von BuchNeithea aequicostata LamarckNeithea tenouklensis CoquandPlicatula reynesi CoquandPlicatula gurgitis Pictet and RouxPlicatula auressensis CoquandOstrea rouviliki CoquandExogyra olWsiponensis SharpeExogyra olisiponensis duplex PaulckeExogyra polygona von BuchExogyra deletteri CoquandCardita doumeti PeronCoquandia italica SeguenzaCorbula sp.

EchinoideaOrthopsis titicacana Cooke

Acanthoceras, Neolobites, and Forbesicerasare well-known late Cenomanian (Acantho-ceratan age) genera distributed mainly in theMediterranean area (Spath, 1926, p. 425;Collignon, 1937, p. 64; Adkins, 1928, p. 243).Exogyra olUsiponensis Sharpe is a late Ceno-manian-early Turonian species of wide distri-

396 VOL. 108


bution (Reeside, 1929). The top of this zoneis considered the top of the Cenomanian, andthe zone is assigned to the latest Cenomanian.The echinoid Orthopsis titicacana was de-scribed first in collections made by Newell inthe Ayavacas limestone of the Titicacaregion. Its association with late Cenomanianammonites confirms Cooke's dating of thisspecies. The fact that the genus Neolobites hasalso been reported from southern Peru (Boit,1926), suggests that the zone of Acanthoceraschasca may be present in southern Peru,probably represented by the lower part of theMoho formation (Newell, 1949, p. 51).

ZONE: OF Coilopoceras jenksiThe Cofior formation and the upper part

of the Quillquifian group (Tembladera sec-tion) are distinguished by Coilopoceras jenksi,new species. It is associated with the follow-ing:CephalopodaMammites nodosoides afer PervinquiarePseudoaspidoceras reesidei, new speciesThomasitesfischeri, new speciesVascoceras aff. Vascoceras silvanense ChoffatBroggiiceras humboldti, new speciesBroggiiceras olssoni, new speciesHoplitoides inca, new species

PelecypodaInoceramus labiatus SchlotheimInoceramus sp.Plicatula gurgitis CoquandPlicatuks reynesi CoquandPlicatulopecten ferryi CoquandCorbula sp.

The genera Mammites, Pseudoaspidoceras,Thomasites, Vascoceras, Hoplitoides, andBroggiiceras constitute the well-known Sal-murian fauna (lower Turonian; Mammitanage) of the European stratigraphers, dis-tributed in the Mediterranean area, southernFrance (de Grossouvre, 1912), Portugal(Choffat, 1886, 1898, ser. 2), Tunisia (Per-vinqui6re, 1907), Middle East (Basse, 1940),Madagascar (Bass6, 1931), India, Brazil,Mexico (Base, 1918), and the United States(Reeside, 1923).

Inoceramus labiatus (Schlotheim) is theworld-wide marker of the lower Turonian. InEngland, Germany, and the United States,the "zone of Inoceramus labiatus" has beenrecognized as at the base of the Turonian.

ZoNE oF Coslopoceras newelliThe Cajamarca formation is characterized

by Coilopoceras newelli, new species. Thisformation is largely of thick-bedded litho-graphic limestones which contain only For-aminifera and gastropods. However, occa-sional interbeds of marl are packed with mol-lusks. In addition to the index species are thefollowing species:Pelecypoda

Inoceramus sp.Inoceramus peruanus BriiggenPlicatulopecten ferryi CoquandLima sp.Cardium lissoni Briiggen

EchinoideaHemiaster fourneli Deshayes

The zone of Coilopoceras newelli is as-signed to the late Turonian, because all thespecies of Coilopoceras known to the writerare Turonian and because the succeedingzone of Buchiceras bilobatum is earliestConiacian.

ZoNE OF Buchiceras bilobatumThe lower part of the Celendin formation

is characterized by Buchiceras bilobatumHyatt in association with the following:Cephalopoda

Barroisiceras (Barroisiceras) haberfellneri vonHauer

Barroisiceras (Barroisiceras) kayi, new speciesBarroisiceras (Solgerites) brancoi SolgerBarroisiceras (Forresteria) basseae, new speciesBarroisiceras (Forresteria) allualdi, Boule, Le-

moine, and Th6veninTissotia hedbergi, new speciesHeterotissotia peroni LissonHeterotissotia bucheri, new species

PelecypodaCucuUlaea maresi CoquandModiola sp.Inoceramus aequivalvis BruggenInoceramus peruanus BriiggenPlicatulopecten ferryi CoquandSpondylus striatus SowerbyLima (Plagiostoma) grenieri CoquandOstrea (Lopha) nicaises CoquandOstrea sp.Ostrea bravoi BrtiggenRoudairia intermedia BruggenCardium pulchrum BruiggenPholadomya elongata MuensterPholadomya quinuana Neumann

1956 397


EchinoideaCyphosoma schlagintweiti BruiggenSeveral species of the group ofHemiasterfourneliDeshayes

In addition, it contains a great number ofunidentified gastropods and bryozoans.From the standpoint of stratigraphy, the

genus Barroisiceras (treated monographicallyby Reeside, 1932, and Basse, 1947) is themost important. Reeside (1932, p. 9) states:"the ammonite genus Barroisiceras is note-worthy because of its wide geographic distri-bution and its apparently small stratigraphicrange. It is reported from deposits of. Coni-acian age in Europe, Africa, South Americaand North America." The genus Tissotiaranges through the Coniacian and Santonian(Pervinquibre, 1907), and the genus Heterotis-sotia has been reported from the lateTuronian of Tunisia (Pervinquiere, 1907, p.379).On the basis of the presence of Barroisi-

ceras, universally recognized as a Coniaciangenus, the zone of Buchiceras bilobatum isassigned to this stage.

ZONE OF Lenticeras baltaiThe upper part of the Celendin formation

is marked by Lenticeras baltai Liss6n. It isassociated with the following:Cephalopoda

?Bostrychoceras sp.

Desmophyllites gaudama (Forbes)Teaniks hourcqi CollignonTexaniles sp.Tissotia steinmanni Liss6nTissotia fourneli (Bayle)2Tissotia hWai KnechtelLenticeras lissoni Knechtel

PelecypodaInoceramus sp.

Lima sp.Ostrea (Phola) nssaises CoquandRoudairia intermedia BruggenCardium Punkhrum Bruggen

EchinoideaHemiaster fourneli DeshayesGoniopygus hemicidariformis BruiggenGoniopygus superbus Cotteau and Gauthier

Collignon (1948, pp. 102-103), in his mono-graph on the Texanitidae, states: " . . . a lafin du Coniacien, le genre Texanites est con-stituE et d6ja repr6sentS par des espZces bien

typiques.... Au Santonien se produit lagrande floraison et la plus grande dispersiong6ographique du Genre Texanites s. str." Inthe Campanian, he adds, "le genre Texanitesn'y apporte qu'un appoint insignificant." Heplaces the Madagascan zone of Texaniteshourcgi at the base of the Santonian and cor-relates it with the zone of Texanites texanusof western Europe and the coast of the Gulfof Mexico.

Bostrychoceras is usually considered to beupper Senonian (Yabe, 1904; Spath, 1921, p.266); Desmophyllites gaudama commonly isfound in Santonian deposits; Tissotia is foundboth in the Coniacian and Santonian; and,according to Spath (1921, p. 267), Lenticerashas been found at about the limit between theConiacian and the Santonian.

Rivera (1949) has described and assignedto the Coniacian a faunule from Pongo deRentema, Rio Marafi6n, which includesPachydiscus (Parapachydiscus) aff. P. (P.)gardneri Reeside, Pachydiscus (Parapachy-discus) sp. indet., Texanites aff. bourgeoisid'Orbigny, Tissotia singewaldi Knechtel, andLenticeras baltai Lisson. Parapachydiscus,however, is an upper Senonian (Parapachy-discan age) genus (Spath, 1921, 1926;Reeside, 1947), and Texanites bourgeoisi isuppermost Coniacian and lower Santonian(de Grossouvre, 1893, p. 73). This faunule, inthe present writer's opinion, is younger thanConiacan.

In Venezuela, Gerhardt (1897) describedTexanites texanum (Roemer), Texanites caia..ensis (Gerhardt), Gauthiericeras lenti Ger-hardt, Gauthiericeras margae (Schlueter),Amaltheus sieversi Gerhardt, and Lenticerasandii Gerhardt from beds later interpreted tobelong to the Colon shale (Liddle, 1928, p.168) which, on the basis of Foraminifera, hasbeen correlated with the Taylor marl (lowerCampanian) of the coast of the Gulf of Mex-ico (Hedberg and Sass, 1937, p. 87).Finally, another significant fauna is foundin Haiti. Reeside (1947) has recorded Pachy-discus ("Parapachydiscus") gardneri Reeside,Pachydiscus ("Parapackydiscus") woodringiReeside, Parapuzozia? sp., Paralenticerassieversi (Gerhardt), and Texanites cf. Tex-anites canaensis (Gerhardt) which he assignsto the late lower Senonian (approximatelySantonian).

VOL. .108398


The present writer thinks that the presencein the zone of Lenticeras baltai of Texanites,Lenticeras, Bostrychoceras, and Desmophyl-lites, and the absence of Barroisiceras andHeterotissotia, indicate Santonian. The com-

mon association of the genera named firstwith Parapachydiscus (Haiti, Venezuela, andthe Umkwelane Hill fauna of Zululand;Spath, 1921) further sustains this view.

GEOLOGIC HISTORYAfter the deposition of the marine upper

Jurassic Chicama beds, the sea withdrewfrom northern and central Peru. Only in a fewareas along the present coast (the Limaenvirons, for instance) did marine sedimenta-tion continue more or less uninterruptedlyfrom the Jurassic into the Cretaceous. Thiswidespread emergence was accompanied orproduced by broad, gentle warping, particu-larly active along the Maraf6n axis wherepre-Mesozoic rocks were exposed to erosion.The Cretaceous sedimentation was begun

by the deposition of the very clean, well-sorted, 600-meter thick Chimu' sandstone,which is found west of the Marafo6n River andsouth of the Jequetepeque River. It was de-posited under conditions of tectonic quies-cence, with no neighboring high lands. Bylate Valanginian time, the sea encroachedover the area on which the Chimu' sand-stone had been deposited, and the shales andlimestones of the Santa formation were laiddown. The Santa formation is thicker (341meters), more calcareous, and richer in ma-rine fossils in the Callej6n de Huaylas thanin areas towards the east and north. It is notpresent east of the Maranfon River or northof the Jequetepeque River. By the end of theValanginian, renewed emergence restrictedthe sea again; gypsum of this age is found inthe Callej6n de Huaylas and conglomeratesare found in the Chicama Valley. An ero-sional surface was formed on which non-marine sedimentation was initiated.The Hauterivian and Aptian stages are

represented in the Callejon de Huaylas by1300 meters of brackish-water shales withinterfingered beds of marine limestone andvolcanic tuffs, the Carhuaz formation, whichintertongues with quartz-sandstone (Goy-llarisquisga formation) towards the east andnorth. The Goyllarisquisga formation, withan average thickness of 600 meters along theMarafi6n River, has a greater distributionthan the earlier Chimui sandstone; it overlaps

earlier Cretaceous sediments and also Jurassicand Triassic rocks. Probably south and westof the Callej6n de Huaylas, the Carhuazformation acquires more marine and volcanicbeds. During this time, volcanism was activein the western lands.

During the early Albian, the Pariahuancalimestone (Callej6n de Huaylas), the Inca(northern Peru), and the Pananga (north-western Peru) formations were deposited.These lithic units are the basal deposits of themarine transgression which advanced east-ward and northward through Albian time,gaining wider spread and uniformity inlithology. These units grade into quartz-sandstones of the Goyllarisquisga formationeast of the Marafo6n River.

During the medial Albian, the transgres-sion reached its maximum expansion. For thefirst time during the Cretaceous the seacovered Marafionia, where poorly fossilifer-ous marls and limestones (Crisnejas forma-tion) were deposited. Westward, along thepresent Cordillera Occidental, during theearly medial Albian, the Chulec formation(richly fossiliferous marls and limestoneswith a maximum thickness of 577 meters inthe Cajamarca area) was deposited. By themiddle of the medial Albian deeper watersand restricted circulation favored the accu-mulation of great quantities of organic mat-ter: the Pariatambo formation of black,strongly bituminous marls and limestoneswas deposited; it has a uniform thickness ofabout 200 meters. The Chulec and Paria-tambo formations are time equivalents of theCrisnejas formation and probably of thePaco, Esperanza, and Aguanuya members ofeastern Peru (Kummel, 1948) and of theArcurquina limestone of the Arequipa region(Jenks, 1947).The deposition of the bituminous lime-

stones and marls of the Pariatambo was

brought to an end by widespread shallowingof the seas and the uplift of the Marafn6n

1956 399

400 BULLETIN AMERICAN MUS]geanticline, where a surface of erosion,including pre-Mesozoic rocks, was formed.Upper Albian-lower Cenomanian, non-marinered beds (Rosa formation), including quartzpebble conglomerates, are found along theMarafo6n River between south of Celendinand Quiches. These red beds interfinger west-ward with 500-meter thick marine marls andargillaceous limestones with peculiar wavybedding and nodular structures (Yumagualformation) which sometimes are close to be-ing coquinas of exogyroids but in which am-monites are strikingly scarce. By medialCenomanian, there was a gradual deepeningof the seas, which again covered Marafionia;wavy-bedded, 300-meter thick limestones(Mujarruin formation) were deposited overmost of the area. Along the coast, the upperAlbian-middle Cenomanian interval is repre-sented by shales and sandstones which suggestnear-by sources at the time of deposition.From the coast to the Marafion River, the

upper Cenomanian is represented by 100-meter thick marls and shales (Romiron for-mation) with an extraordinarily rich mol-luscan fauna. The Romir6n formation be-comes more calcareous and less fossiliferouseastward; it seems that it was deposited undershallow waters and that along the Marafionaxis, the sea was deeper.The lower Turonian is represented by yel-

low, very fossiliferous shales along the coast(upper Quillquiian in Tembladera), by graymarl interbedded with massive beds of graysublithographic limestone (Coior formation)along the western -Andes, and by thick-bedded, massive, gray limestones (Caja-marca formation) along the Mara6on Riverand in central Peru. During this time, thick-bedded, poorly fossiliferous limestones tendto replace the fossiliferous marls. In lateTuronian, thick-bedded, dark gray, litho-graphic limestones (Cajamarca formation)which carry mostly Foraminifera and gastro-pods were deposited over northern and cen-

tral Peru. Occasional thin interbeds of argil-laceous marl carry locally abundant mollusksand echinoids. During the Cretaceous the lateTuronian was the time of maximum spreadof the sea. It covered the whole Andean belt.It would seem that Marafionia was incon-

EUM OF NATURAL HISTORY VOL. 108

spicuous as a physiographic or structuralfeature. Apparently the thick-bedded lime-stones of the Cajamarca and Jumasha forma-tions of the Andean belt change facies intothe Chonta formation of eastern Peru, "ofdark gray shale, with interbedded units ofsiltstone, calcareous siltstone and some lime-stone" (Kummel, 1948, p. 1240), which lapsthe border of the Brazilian craton.By the early Coniacian, a marked change

in the character of sedimentation took place.Instead of thick-bedded limestones, yellowshales and marls (Celendfn formation), whichcarry a very rich molluscan fauna (both interms of number of species and number ofindividuals), were deposited. These depositsare missing west of the continental divide,apparently beveled by an unconformity,although offlap may also be a cause. The seashad become shallow and reduced in extent;gypsum was deposited in localized areas.By the late Santonian, in connection withthe orogeny that affected the coastal areas,

the western lands were being raised andpushing eastward, producing widespreademergence and the end of marine sedimenta-tion in the Andean belt. The raised westernlands were the source of thick red-bed flyschdeposits (Chota formation) found over thewestern Andes.Sometime during the late Senonian-earlyTertiary an orogeny produced the folds and

faults that dominate the structure of thewestern Andes. After this important orogenicperiod, new red-bed clastics (Pocobambaformation) were deposited, and considerableintrusive and extrusive igneous activity tookplace.

In Tertiary times, the Marafi6n geanticlinewas uplifted again and exposed pre-Mesozoicrocks to erosion, so that the CordilleraCentral has abundant outcrops of pre-Cretaceous rocks, in contrast with the Cordil-lera Occidental where Cretaceous sedimentsand Tertiary volcanics are prevalent, andwith the Cordillera Oriental where Creta-ceous and Tertiary sediments are the mostabundant.

Following a period of planation, theAndean system has been raised to form thepresent actively dissected, high plateau.

STRATIGRAPHIC SECTIONS

SECTION 1. LAJAS

Section measured along the south side of the Chotano River, from 500 meters west of ElIngenio to 500 meters west of the town of Lajas, 9 kilometers west of Chota.

CHOTA FORMATION METERS

51. The lowest beds are of unconsolidated, coarse, strongly cross-bedded, yellowish and redquartz-sandstone. They are followed by conglomerates of quartzite and chalcedony cob-bles in a red sandy matrix. Thickness estimated as over 100 meters

DISCONFORMITYCAJAMARCA FORMATION50. Limestone, medium to light gray, sublithographic, thick-bedded, massive, with fossiliferous

(Ostrea, Inoceramus, Hemiaster) marly interbeds.5749. Shale, bluishgray. 1248. Limestone, medium gray, lithographic, thick-bedded.1247. Marl, bluish gray, nodular to shaly, fossiliferous, interbedded with thick-bedded, massivelimestone.10

46. Limestone, slightly bituminous, medium to light gray, lithographic, massive, thick-bedded,with a few interbeds of bluish marl.87

45. Limestone, medium to dark gray, sublithographic, medium-bedded, with interbeds ofsplintery, poorly fossiliferous (Roudairia intermedia, Cardium, Inoceramus, Hemiaster),medium gray, white-weathering marl . . . . . . . . . . . . . . . . . . . . . . 32

TOTAL, CAJAMARCA FORMATION: 210 meters

CoSoR FORMATION44. Shale, brownish gray, soft, crumbly . . . . . . . . . . . . . . . . . . . . . . . 3043. Marl, light gray to yellowish gray, nodular, fossiliferous. . . . . . . . . . . . . . . . 4

42. Shale, brownish yellow to greenish gray, soft, fossiliferous (Coilopoceras jenksi), with a fewinterbeds of brownish yellow limestone... . . . . . .2.0...... . . . . .

4

41. Marl, light gray to white, laminated to nodular, weathers yellowish . . . . . . . . 440. Shale, brownish yellow, soft, poorly exposed.. .239. Marl, light gray nodular, shaly, fossiliferous . . . . . . . .. . . . . . . . . .4..

38. Shale, bluish gray, laminated, interbedded with nodular, yellowish brown limestone . . 12

37. Limestone, massive, gray, ridge-forming 2

36. Marl, light bluish gray, nodular, fossiliferous.. . ........... . . .. 19

35. Marl, light gray, nodular, shaly, interbedded with massive light gray limestone. . . . 1334. Marl, light gray, nodular, friable, fossiliferous (Coilopocerasjenksi, Hoplitoides inca) . . . 12

33. Marl, yellowish gray, slightly ferruginous, nodular, weathers brownish, fossiliferous (Coil-opoceras, Hoplitoides), with interbeds of thick-bedded, massive, fossiliferous (Orthopsistiticacana), light brown limestone.12

TOTAL, COROR FORMATION: 157 meters

ROMIR6N FORMATION32. Shale, brownish to yellowish, friable, with thin interbeds of nodular, coqunoid, very fos-

siliferous (Exogyra olisiponensis), rusty, yellowish brown argillaceous limestone . . . . 102

TOTAL, ROMIR6N FORMATION: 102 meters

MUJARRI6N FORMATIONCULEBRA MEMBER31. Marl, light gray, chalky, thin-bedded, nodular, soft, extraordinarily fossiliferous (Exogyra

africana, Exogyra oisiponensis, other exogyroids, Neithea tenouliensis, Negthea ak6tus,Tetragramma sp., Orthopsis titicacana), weathers light gray to yellowish gray . . . . 76

CHORO MEMBER30. Limestone, gray to bluish gray, massive, very thick-bedded, slightly nodular, fossiliferous

(Exogyra cf. ponderosa), weathers light gray, forms ascarp.106401


METERS29. Limestone, argillaceous, light gray, nodular, thick-bedded, fossiliferous (E. cf. ponderosa),

interbedded with massive, light bluish gray limestone . . . . . . . . . . . . . . . 105TOTAL, MUJARRUN FORMATION: 287 meters

YUMAGUAL FORMATION28. Marl, somewhat bituminous, soft, nodular, richly fossiliferous (Exogyra mermeti), inter-

bedded with a few beds of massive, wavy-bedded, light gray, argillaceous limestone . . . 15927. Limestone, medium to dark bluish gray, thick-bedded, massive, nodular, very fossiliferous

(Paraturrilites lewesiensis, E. mermeti), interbedded with very nodular, thin-bedded,soft, fossiliferous (rudistid debris), slightly bituminous marl . . . . . . . . . . . . 76

26. Shale, calcareous, fossiliferous (Ostrea, Corbula).4.. . . . . . . . . . . . . . . 425. Limestone, argillaceous, medium to darkgray. 824. Limestone, dark gray, massive, hard, thick-bedded, weathers light yellowish gray . . 823. Marl, brownish gray, silty, very nodular, fossiliferous, interbedded with thick, massive

beds of bluish gray, silty limestone . . . . . . . . . . . . . . . . . . . . . . . 12622. Shale, silty, brownish gray to light gray, nodular, soft . ... . . . . . . . . . . . 4621. Marl, silty, yellowish and yellowish brown, nodular, interbedded with massive, medium-

bedded, fossiliferous, gray-weathering argillaceous limestone . . . . . . . . . . . 11120. Covered. Probably of soft marls . . . . . . . . . . . . . . . . . . . . . . . . 89ToTAL, YUMAGUAL FORMATION: 627 METERS

PARIATAMBO FORMATION

19. Limestone, bituminous, black, massive, medium-bedded, platy, fossiliferous, weathersbrownish black................. . . . .... . .. . ... 40

18. Limestone, argillaceous, bituminous, black, thin-bedded, shaly, with interbeds of black,bituminous shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

17. Limestone, bituminous, black, massive, medium-bedded, slabby, fossiliferous, weathersdark grayish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

TOTAL, PARIATAMBO FORMATIoN: 261 METERS

CHULEC FoRMATION16. Marl, grayish to brownish, thin-bedded, shaly, fossiliferous (Knemiceras sp.), with few

interbeds of massive, brownish gray to medium gray, fossiliferous limestone.25515. Limestone, dark gray to black, medium-bedded, fossiliferous (Knemiceras, Corbula, Exogyra

minos), with few shaly interbeds . . . . . . . . . . . . . . . . . . . . . . . . 1014. Covered. A few outcrops show a soft, bluish gray, calcareous shale . . . . . . . . . . 9813. Limestone, argillaceous, gray, with interbeds of bluish gray, shaly marl.1512. Shale, black, splintery ........ . . . . . . .. . . . . ......... 2111. Limestone, dark gray, fossiliferous (Parengonoceras pernodosum), weathers yellowish white. 1010. Limestone, slightly argillaceous, medium to dark gray, thin- to medium-bedded, fossilifer-

ous (Lyelliceras lyelli, Exogyra minos, Liophista sp., Enallaster sp.), weathers yellowishwhite, with a few intercalations of yellowish marl . . . . . . . . . . . . . . . 65

TOTAL, CHULEC FORMATION: 474 METERS

INCA FORMATION9. Shale and quartz-siltstone, ferruginous, thin-bedded, poorly exposed . . . . . . . . . 308. Limestone, arenaceous, dark gray, weathers yellowish brown, with interbeds of rusty,

yellowish to brownish shale . . . . . . . . . . . . . . . . . . . . . . . . . . 137. Quartz-siltstone, ferruginous, iron gray, massive, thick-bedded, weathers rusty brown . . 46. Shale, ferruginous, brownish to greenish, with interbeds of thick-bedded, rusty, yellow-

weathering gray limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 135. Limestone, arenaceous, glauconitic, ferruginous, gray, thick-bedded, rusty.74. Shale, bluish black, fossiliferous (Trigonia sp., Exogyra minos), with interbeds of massive,

fossiliferous (Enaliaster sp., Exogyra sp.), rusty dark gray limestone . . . . . . . . 53. Shale, black to bluish gray, laminated, soft, with concretions of iron oxide, with interbeds

of ferruginous, calcareous, fossiliferous, brownish yellow quartz-siltstone . . . . . . . 16

402 VOL. 108


METERS2. Quartz-siltstone, white to yellowish brown, fine- to medium-bedded, with a few interbeds of

shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111. Shale, ferruginous, slightly calcareous, bluish to black, fossiliferous (Pterotrigonia tocai-

maana, Exogyra aguila), brown-weathering, with interbeds of massive, fossiliferous, thick-bedded, yellow-weathering, dark gray, arenaceous, ferruginous limestone. . . . . . . 15+

TOTAL, INCA FORMATION: 114+ METERS

SECTION 2. BAMBAMARCASection measured from Quebrada Maigas, 2 kilometers west of Bambamarca, to the out-

skirts northwest of this town.

CHOTA FORMATION METERS

24. Conglomerate of perfectly rounded cobbles of white quartzite in a scanty matrix of redsandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500+

TOTAL, CHOTA FORMATION: 500+ METERS

DISCONFORMITYCELENDfN FORMATION23. Shale, dark gray, yellow-weathering, with few calcareous interbeds, poorly exposed . . 13222. Shale, bluish black, laminated with few intercalations of nodular, fossiliferous (Desmophyl-

lites gaudama, Bostrychoceras sp.), yellowish limestone . . . . . . . . . . . . . . . 4121. Shale, bluish gray, laminated, soft, with thin interbeds of fossiliferous marl . . . . . . 3620. Marl, light gray, thin-bedded, weathers white . . . . . . . . . . . . . . . . . . . 4119. Limestone, dark orange-gray, gray-weathering with interbeds of fossiliferous marl. . . . 3018. Shale, calcareous, light whitish gray, contains Hemiaster sp. . . . . . . . . . . . . . 21

17. Limestone, argillaceous, light gray, nodular, with intercalations of marl . . . . . . . . 416. Shale, greenish yellow to brown, laminated, crumbly, with a few intercalations of massive,

yellowish brown, argillaceous limestone . . . . . . . . . . . .. . . . . . . . 13

15. Marl, nodular, very fossiliferous (Buchiceras bilobatum, Heterotissotia peroni, H. bucheri,Barroisiceras haberfellneri) . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

14. Shale, yellowish brown, soft, with interbeds of massive, ledge-forming, gray limestone . . 4

13. Marl, brownish yellow, slightly fossiliferous .... . . . . . . . . . . . . . . . .

12. Limestone, very argillaceous, yellowish, nodular.1... .. . .... . ..... . I

11. Shale, yellow ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

TOTAL, CELENDiN FORMATION: 348 METERS

CAJAMARCA FORMATION10. Limestone, arenaceous, medium gray, massive, thick-bedded, contains Foraminifera,

weathers dark gray.6... .. .. . ........... . ...... . .. .. . .

9. Limestone, argillaceous, light brownish gray, nodular . . . . . . . . . . . . . . . . 68. Limestone, light brownish gray, massive, thick-bedded, ridge-forming, weathers dark gray,

contains Foraminifera and shell debris . . . . . . . . . . . . . . .. . . . .. 347. Marl, bluish gray, nodular toshaly.. . . . . . . . . . . . . . . . . . . . 13

6. Limestone, slightly argillaceous, massive, thick-bedded, weathers light gray . . . . . . 465. Marl and calcareous shale, soft, bluish gray, fossiliferous (Coilopoceras newelli).644. Limestone, light gray, massive, thick-bedded, weathers light gray, ridge forming . . . s183. Limestone, argillaceous, light brownish gray, white-weathering, with interbeds of laminated

calcareous shale.31. . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. Shale, calcareous, bluish gray, nodular, richly fossiliferous (Coilopoceras newelli, Lima sp.,

Cardium lissoni, Hemiaster sp.) . . .. . ... . . . . . . ... . . . . . . 31. Limestone, dark gray, massive, thick-bedded, weathers to a red soil . . . . . . . . . 60+

TOTAL, CAJAMARCA FORMATION: 281+ METERS

SECTION 3. HUALGAYOC

Section measured beginning in Quebrada Hualgayoc, 2 kilometers northeast of Hualgayoc,and end'ing in Yerba Santa, 7 kilometers southeast of Hualgayoc.

4031956


ClELENDiN FORMATION METERS53. Shale, light grayish blue, fossiliferous, with interbeds of thin, nodular marl.60+

TOTAL, CELENDfN FORMATION: 60+ METERS

CAJAMARCA FORMATION52. Limestone, medium brownish gray, sublithographic, massive, thick-bedded, weathers dark

bluish gray.7051. Limestone, argillaceous, dark bluish gray, somewhat nodular, fossiliferous (Ostrea sp.,

Inoceramus sp.), with a few interbeds of massive limestone.4350. Shale, calcareous, bluish gray, splintery, soft, fossiliferous.1349. Marl, bluish gray, nodular, contains Coilopocerasnewelli. . . . 1048. Shale, calcareous, light bluish gray, splintery . . . . . . . . . . . . . . . . . . . 247. Limestone, medium gray to brownish gray, medium- to thick-bedded, weathers dark gray,

with interbeds of light bluish gray, nodular, fossiliferous marl.7046. Shale, calcareous, light bluish gray,soft. 645. Limestone, medium brownish gray, sublithographic, massive, thick-bedded, with interbeds

of nodular, splintery, light bluish gray, argillaceous limestone . . . . . . . . . . 7144. Marl, bluish gray, shaly, soft. .2743. Limestone, argillaceous, light gray to light brownish gray, nodular, weathers light gray . 4542. Limestone, light gray to light brownish gray, massive, sublithographic, medium- to thick-

bedded, weathers medium gray.12341. Limestone, slightly argillaceous, medium gray, nodular, thin-bedded.3640. Limestone, light gray, lithographic, massive, thick-bedded, weathers whitish gray, withinterbeds of laminated argillaceouslimestone.. . . . . . . . . . . . . . . 18

TOTAL, CAJAMARCA FORMATION: 434 METERS

COROR FORMATION39. Marl, light grayish blue, soft, splintery.5438. Limestone, gray, thick-bedded, weathers lightgray. 937. Limestone, light gray, nodular, medium- to thick-bedded, weathers whitishblue. 27TOTAL, Co1OR FORMATION: 90 METERS

ROMIR6N FoRMATION36. Shale and marl, yellowish brown, poorly exposed.72MUJARRtN FORMATIONCULEBRA MEMBER35. Marl, medium gray, soft, nodular, medium- to thick-bedded, fossiliferous (Exogyra afri-

cana), weathers light gray to grayish white. 69CHOROMEMBER34. limestone, medium gray, massive, thick-bedded, fossiliferous (Exogyra cf. ponderosa)

weathers light gray, with a few thin interbeds of nodular limestone . . . . . . . . . 194TOrAL, MUJARRfN FORMATION: 263 METERSYUMAGUAL FORMATION33. MarIl, light gray, very poorly exposed, interbedded with medium- to thick-bedded, fossil-iferous (Exogyra mermdi), dark gray limestone.5932. Limestone, bituminous, dark gray, thick-bedded, fossiliferous (Ostrea scyphax, echinoids),with chert nodules, interbedded with soft marls. 8431. Marl, light gray, soft, nodular, thick-bedded, with interbeds of fossiliferous, massive, dark

graylimestone which contains chert nodules . . . . . . . . . . . . . . . . . 16330. Marl, light gray, nodular, poorlyexposed, with interbeds of thick-bedded, massive, fossil-

iferous, cherty, brownish graylimestone.3029. Quartz-iatstone, calcareous, dark yellowish brown, cross-bedded, with a few interbeds ofdark gyarenaceous limestone. . . . 1128 4maCtome, medium grayto light gray, silty 25

ArU VOL. 108


METERS27. Quartz-sandstone, brownish yellow, medium- to fine-grained, thick-bedded . . . . . . 326. Limestone, dark gray, massive, thick-bedded, with interbeds of fossiliferous (Ostrea

scyphax), nodular, silty, argillaceouslimestone.. . . . . . . . . . . . . . . . 19625. Marl, light gray, soft, poorly exposed, with interbeds of massive, medium- to thick-bedded,

fossiliferous (Ostrea sp., Exogyra sp.), medium gray, bituminous limestone which formsledges between the marly beds ... .. .. . . .. . .. . .. . ... . .. . 189

TOTAL,YUMAGUAL FORMATION: 760 METERS

PARIATAMBOFORMATION24. Limestone, bituminous, dark gray, massive, medium-bedded, fossiliferous (Oxytropidoceras

carbonarium) ...... . . . . . . . . . . . . . . . . . . . . . . . . . . 7423. Marl, bituminous, black, shaly ..... . . . . . . . . . . . . . . . . . . . . . 1522. Limestone, bituminlous, black, massive, well-bedded, platy, fossiliferous (Oxytropidoceras sp.) 1521. Limestone, bituminous, black, medium- to thin-bedded, platy, fossiliferous (Oxytropido-

ceras sp. and Lyelliceras ulrichi), weathers medium gray . . . . . . . . . . . . . 920. Marl, bituminous, thin-bedded, soft, poorly exposed.. . . . . . . . . . . . . . . 60

TOTAL, PARIATAMBO FORMATION: 168 METERS

CHULEC FORMATION19. MARL, light gray, nodular to shaly, soft, poorly exposed.. . . . . . . . . . . . . 4018. Diorite dyke17. Limestone, argillaceous, dark gray, shaly, splintery, weathers light gray; the upper part is

covered.3016. Limestone, argillaceous, dark gray, thin-bedded to laminated, soft, poorly exposed, with

interbeds of fossiliferous, dark gray, massive limestone.. . . . . . . . . . . . . 3215. Marl, light gray, shaly, splintery, poorly exposed.. . . . . . . . . . . . . . . 10614. Shale, bluish gray, laminated, weathers yellowish.. . . . . . . . . . . . . . 10

13. Marl, dark gray, splintery, weathers light gray . . . . . . . . . . . . . . . . . . 4

12. Diorite dyke, 50 meters thick11. Marl, grayish black, shaly, splintery, fossiliferous (Knemiceras sp.,LiophisthLsp.,Enal-

laster peruanus), weathers yellowish gray, with thick interbeds of massive, dark gray to

blacklimestone..60TOTAL, CHULEC FORMATION: 282 METERS

INCA FORMATION10. Quartz-sandstone, calcareous, ferruginous, olive green, fossiliferous (Trigonia sp., Exo-

gyra minos).9. Shale, dark gray, laminated, weathers dark yellowish . . . . . . . . . 3. . . . . .

8. Quartz-sandstone, calcareous, ferruginous, greenish to reddish, hard, fine-grained, weathersdark brownish red, with thin interbeds of brown limestone . . . . . . . . . . 9

(The section is interrupted here by a thick diorite sill, the base of which is already in the Goyl-larisquisga formation.)

GOYLLARISQuISGA FORMATION7. Quartz-sandstone, white to light gray, medium-grained, medium- to thick-bedded, weathers

brownish red, interbedded with light gray to purple shale . . . . . . . . . . . . . 696. Diorite sill, 75 meters thick5. Quartz-sandstone, white to yellowish gray, medium-grained, thick-bedded, weathers red-

dish brown, formscliffs.484. Quartz-sandstone, white to gray, medium-grained, medium- to thick-bedded, lenticular,

weathers yellowish brown with interbeds of laminated, silty, micaceous, white shale 65

3. Shale, slightly ferruginous, white to gray, soft, laminated, somewhat micaceous. . . 152. Quartz-sandstone, light brownish, with interbeds of whitish purple, laminated shale. . 151. Quartz-sandstone, white to light brownish, medium-grained, very massive, compact, thick-

bedded, with few intercalations of shale . . . . . . . . . . . . . . . . . . . . . 18+TOTAL, GOYLLARISQUISGA FORMATION: 230+ METERS

1956 405


SECTION 4. CELENDfNComposite section (fig. 16); the lower Goyllarisquisga formation was estimated along the

road from Celendin to Balsas, 2 kilometers below Hacienda Lim6n; the rest of the section wasmeasured from the northwestern outskirts of the town of Celendin (Quebrada Parapuquio)to Quebrada Melendez, 500 meters north of Hacienda La Quinua and 6 kilometers northwestof Celendin. It includes the type of the Celendin formation.

GAMPANIAN ?

SANTONIAN Lenticeras baltal zone -=-

CONIAGIAN Buhiceras bilobatu zone

Coilopoceras newelU zoneTURONIAN

Coilopoceras jenksi zone

Acanthoceras chscazone

Exogyra africana zone

CENOMANIANExogyra cf. ponderosa zone

Paratzrilits lewesiensis zone

Ostrea scyphax zone

ALBIAN Oxyfropikoceras carbonarium zone

Knemiceras raiondli zone

APTIAN

NEOGOMIAN

JURA- TRIASSIGC

CHOTA FM. (151m.)

GELENDIN FM.(120rr.)

GAJAMARCA FM.(302min.)

CONOR FM. (144in)ROMIRON FM. (79m.)

PULLUICANAGROUP

(undiff.)(1159 T.)

GRISNEJAS FM.(410 m.)

GOYLLARISQUISGAFM. (690 n.)

FIG. 16. Celendfn stratigraphic section.

II

406 VOL. 108

BENAVIDES: CRETACEOUS SYSTEM IN PERU 4

CHOTA FORMATION METERS74. Quartz-sandstone and quartz-siltstone, light whitish gray, poorly consolidated, with few

reddish interbeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122+73. Shale and sandstone, red, soft; includes at the top a 90-centimeter thick conglomerate of

perfectly rounded cobbles of quartzite . . . . . . . . . . . . . . . . . . . . . 29TOTAL, CHOTA FORMATION: 151+ METERS

CELENDiN FORMATION72. Shale, yellow, with a few thin, calcareous beds which contain Lenticeras- baltai, Tissotia stein-

manni, T. fourneli, Texanites hourcqi, Ostrea nicaisei, Lima grenieri . . . . . . . . . 10671. Limestone, light brownish gray, massive, with a few interbeds of argillaceous, nodular

limestone; weathers dark gray, contains alveolinellid Foramin'ifera, with thin interbedsof argillaceous, nodular limestone . . . . . ... . . . . .. . . .. ... . . 60

70. Marl, grayish white, packed with Hemiasterfourneli.U ................ 369. Shale, calcareous, yellow and bluish gray, soft, friable, with thin interbeds of nodular,

yellowish argillaceous limestone; contains Buchiceras bilobatum, Heterotissotia peroni, H.bucheri, Tissotia hedbergi, and several species of Barroisiceras .... . . . . . . . 86

68. Limestone, argillaceous, gray.......................... . 167. Shale, yellow and silver gray . . . . . . . . . . . . . . . . . . . . . . . . . . 26

TOTAL, CELENDfN FORMATION: 302 METERS

CAJAMARCA FORMATION66. Limestone, gray, medium- to thick-bedded, weathers dark gray.. . . . . . . . . . . 7565. Limestone, medium gray, lithographic, massive, medium- to thick-bedded, weathers dark

gray.6864. Limestone, medium gray, thin- to medium-bedded, sublithographic, weathers dark gray 4563. Shale, splintery, bluish gray ..... . . . . . . . . . . . . . . . . . . . . . . 462. Limestone, medium gray, sublithographic, medium- to thick-bedded, weathers dark gray. 1461. Limestone, medium gray, thin-bedded, somewhat nodular . . ... . . . . . . . . . 260. Limestone, medium gray, massive, sublithographic, medium-bedded......... . 859 Limestone, argillaceous, light bluish gray, nodular.. . . . . . . . . . . . . . . . 858. Limestone, medium gray, sublithographic, medium- to thick-bedded, weathers dark gray . 857. Marl, medium bluish gray, shaly, splintery...... ... . ... . . ... . .. 956. Limestone, brownish gray, sublithographic, massive, thick-bedded .... . ... . 5

TOTAL, CAJAMARCA FORMATION: 246 METERS

COIOR FORMATION55. Shale,yellow. 554. Shale, yellow, with interbeds of light gray, fossiliferous limestone . . . .... . . .. 753. Limestone, argillaceous, light gray, nodular, weathers whitish gray, contains Coilopoceras

jenksi, Mammites afer, and Hemiaster sp.................. . 5252. Limestone, argillaceous, light gray, weathers dark gray, with thin interbeds of marl 80

TOTAL, Co1oR FORMATION: 144 METERS

ROMIRON FORMATION51. Shale, greenish and yellowish gray, splintery, laminated ............ . . . 2050. Limestone, argillaceous, yellowish brown, nodular, fossiliferous (Exogyra olisiponensis) . - 149. Shale, greenish gray, splintery, soft, yellow-weathering, with interbeds of nodular, brownmarl. 7

48. Marl, ferruginous, yellowish brown, nodular, interbedded with yellow, very fossiliferous(Acanthoceras chasca, A. sangalense, A. pollocense, Forbesiceras sp., Neolobites kummeli,Exogyra olisiponensis) limestone.3.... . . . . . . . . . . . . . . . . . . .

47. Shale, light gray, splintery . 346. Shale, light grayish blue, laminated, splintery, yellow-weathering, with thin interbeds of

nodular, fossiliferous, iron-stained, argillaceous limestone . .. .. . .. . . . . . 2345. Marl, yellowish, nodular, contains numerous specimens of Exogyra olisiponensis ... 244. Shale, light greenish yellow, laminated, fossiliferous (Lissoniceras mermeti, Neolobites kum-

1956 407

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYMETERS

mel, Acanthoceras sp.) with thin interbeds of nodular, iron-stained, brownish limestone. 20TOTAL, RoMIR6N FORMATION: 79 METERS

PULLUICANA GROUP (UNDIFFERENTIATED)43. Limestone, argillaceous, weathers grayish black. . . . . . . . . . . . . . . . . . . 1042. Limestone, gray, massive, thick-bedded, karstic . ... ... . . . . ...... 12941. Shale, calcareous, yellow.3.... .. ..... .... ..... . . . . . ... 340. Limestone, argillaceous, gray, thick-bedded, karstic, contains Exogyra cf. ponderosa . . 6839. Limestone, gray, karstic, weathers dark gray . . . . . . . . . . . . . . . . . . . 3338. Limestone, dark gray, massive, thick-bedded, karstic, with poorly exposed interbeds of

marl.29037. Shale, calcareous, yellow to brown, fossiliferous (Exogyra mermeti).5836. Limestone, brownish gray, massive, thick-bedded, weathers dark gray, with interbeds of

marl.2435. Shale and quartz-siltstone, yellow, soft . . . . . . . . . . . . . . . . . . . . . 2434. Limestone, gray-blue, massive, thick-bedded, with argillaceous interbeds. 1533. Shale and quartz-siltstone, calcareous, yellow to brown, soft, with few interbeds of fossil-

iferous, brownish, argillaceous limestone . . . . . . . . . . . . . . . . . . . . . 5932. Shale, calcareous, yellow, with interbeds of grayish, massive, fossiliferous (Ostrea scyphax)

limestone.. 2931. Limestone, argillaceous, gray, soft, very fossiliferous (Enallaster sp., 7Bothriopygus sp.) . . 4230. Quartz-siltstone, calcareous, yellow.5........ . . . . . . . . . . . . . . .S29. Limestone, bluish gray, massive, thick-bedded... . ... . . . . .. 1928. Limestone and marl, bluish gray, thick-bedded . . . . . . . . . . . . . . . . .

. . 2027. Limestone, dark gray, massive, thick-bedded, weathers bluish gray.7826. Limestone, dark gray, massive, thick-bedded, with interbeds of soft, light gray marls . 7125. Limestone, gray, massive, karstic, thick-bedded, weathers bluish gray.14724. Marl, light gray, weathers yellowish white . . . . . . . . . . . . . . . . . . . . 923. Limestone, bluish gray, massive, ridge-forming, with few interbeds of marl. 26

TOTAL, PULLUICANA GROUP: 1159 METERS

CRISNEJAS FORMATION22. Limestone, argillaceous, light gray, thin-bedded, yellowish-weathering, with interbeds of

splintery, green to white shale . . . . . . . . . . . . . . . . . ..621. Shale, brownish to yellowish, thin-bedded, crumbly . . . . . . . . . 720. Marl, light brown, slightly nodular, thin-bedded, very fossiliferous (Lyelliceras pseudolyelli,

Knemiceras ovsae, Enallaster sp.) . . . . . . . . . . . . . . . . . . . . . . . 119. Marl, light gray, splintery . . . . . . . . . . . . . ..1218. Limestone, dark gray, weathers lightgray.. . . . . .

. . . . . . . . . . . . . 217. Shale, calcareous, light greenish grayto yellow, splintery . . . . . . . . . . . . . . 5516. Shale, calcareous, light gray, thin-bedded, soft, fossiliferous (Knemiceras sp.), with thick

interbeds of dark gray, massive limestone . . . . . . . . . . . . . . . . . . . 3615. Shale, yellow, crumbly, with few interbeds of gray limestone . . . . . . . . . . 3714. Marl, light greenish or brownish gray, thin-bedded, soft, interbedded with laminated,

fossiliferous, graylimestone . . . . . . . . . . . . . . . . . . . . . . . . . . 2713. Shale, calcareous, light grayto yellowish, splintery, fossiliferous (Knemiceras sp., Liopisthagigan)..... 312. Limestone, gray, nodular, contains limonitized echinoids (Enallaster sp.).. 311.Marl, light grayto yellowish, thin-bedded, soft, with interbeds of nodular, dark gray lime-

stone..84....

10. limestone, dark gray, weathers light gray .. . .9. Shale, yellow, finely laminated, splintery, with thin interbeds of nodular, fossiliferous

(Parengcnxro pernodosum, P. tetranodosum, P. haasi, Knemniceras attenuatum, Pro-

tanisoceras blancheti), dark brownish limestone . . . . . . . . . . . . . . . . 62

8& Shale, light gray, with interbeds of gray limestone . . . . . . . . . . . . . 677. Shale, light grayto yellowish,crumbly . . . . . . . . . . . . . . . . . . . . . 15

VOL. 108408


METERS6. Marl, yellow, shaly, soft, with interbeds of bluish gray, rusty-weathering arenaceous lime-stone.19

5. Marl, lightgray. . 44. Shale, gray, finely laminated, soft, brownish-weathering, with thick interbeds of massive,

iron-stained, grayish brown, highly fossiliferous (Pterotrigot-ia tocaimaana, Yaadiahondaana, Buchoirigonia abrupta, Knemiceras raimondii pacificum, K. gabbi, Enallasterperuanus, Holectypus planatus numismalis, Bothriopygus sp.) limestone....... .

293. Shale and quartz-siltstone, brownish gray, finely bedded, crumbly, poorly fossiliferous,

with few interbeds of quartz-sandstone . . . . . . . . . . . . . . .. . .... 26TOTAL, CRISNEJASFORMATION: 410 METERS

GOYLLARISQUISGA FORMATION2. Quartz-sandstone, white to gray, coarse-grained to pebbly, thick-bedded, cross-bedded,

weathers rusty red to yellowish brown, has interbeds of carbonaceous shale . . . . . 6501. Conglomerate; ill-assorted subrounded pebbles and cobbles of dark gray limestone in a

chocolate-red, calcareous quartz-sandstone matrix................ . 40TOTAL, GOYLLARISQUISGA FORMATION: 690 METERS

UNCONFORMITYJURASSICPUCARA GROUP

Limestone, medium gray, thick-bedded

SECTION 5. POLLOC

Section measured from 1 kilometer west of Hacienda Polloc to Hacienda Sangal, 4 kilometers

west of Encafiada, on the Cajamarca to Celendin road.

CELENDiN FORMATION METERS

75. Shale, slightly calcareous, green to bluish gray, splintery, very fossiliferous (Heterotissotiaperoni, H. bucheri, Barroisiceras mite, ;Buchiceras bilobatum), with thin interbeds offossiliferous marl.. 30+

. . . . . . . . . . . . . . . . . . . . . . . . .

274. Limestone, purple gray, massive ..... . . . . . . . . . . . . . . . . . . . . 273. Shale, slightly calcareous, grayish green.. . . . . . . . . . . . . . . . . . . . 22

TOTAL, CELENDIN FORMATION: 54+ METERS

CAJAMARCA FORMATION72. Marl, light gray ..4871. Limestone, argillaceous, weathers gray blue..4770. Limestone, gray, thick-bedded, massive .... . . . . ...... . . . . . . . . 2269. Limestone, gray, medium to thick-bedded, slabby.. . . . . . . . . . . . . . . . . 7868. Limestone, massive, weathers dark gray .... . . . . . . . ........... 167. Limestone, argillaceous, finely bedded, somewhat nodular, weathers dark gray . . . . . 566. Shale, greenish gray, splintery, finely laminated, fossiliferous (Coilopoceras newelli, Cardium

lissoni, Tetragramma sp.) . . . . . . . . ... . . .6......... .. . . . 665. Marl, light brownish gray, white-weathering, nodular, fossiliferous (Inoceramus sp., Ostrea

sp., Coilopoceras newelli, Tetragramma sp.) . . . . . . . . . . . . . . . . . . . .

64. Limestone, light brownish gray, medium- to thin-bedded or even laminated, with interbedsof silty and argillaceous limestone. . . . . . . . . . . . . . . . . . . . . . . .316

63. Limestone, light brownish gray, lithographic, thick-bedded, massive, karstic, contains

large gastropods .. 1662. Limestone, argillaceous, slightly nodular . . . . . . . . . . . . . . . . . . . . 461. Limestone, slightly argillaceous, gray, massive, fossiliferous (gastropods). . 1060. Limestone, light gray, massive, thick-bedded, weathers dark bluish gray..959. Limestone, argillaceous, light bluishgray..30

TOTAL, CAJAMARCA FoRMATION: 699 METERS

1956 Ioo


COROR FORMATION METERS58. Shale, greenish and bluish gray, splintery, very fossiliferous (Coilopoceras jenksi, Plicatulo-pecten ferryi).1057. Shale, gray, weathers yellow . . . . . . . . . . 1. . . . . . . . . . . . . . . . 1556. Marl, gray, splintery, weathers light gray . . . . . . . . . . . . . . . . . . . . . 1055. Marl, yellow and green, fossiliferous (Coilopoceras jenksi, Hoplitoides inca, Hemiaster sp.,Inoceramus sp.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1354. Shale, brownish and greenish gray . . . . . . . . . . . . . . . . . . . . . . . 453. Limestone, light bluish gray, massive . . . . . . . . . . . . . . . . . . . . . . . 752. Shale, calcareous, dark green to bluish, friable . . . . . . . . . . . . . . . . . . . 851. Marl, gray blue and yellow, nodular, fossiliferous (Coilopocerasjenksi, Hemiaster sp.), withsome green and yellow shale interbeds. . . . . . . . . . . . . . . . . . . . . . 850. Limestone, very argillaceous, light gray . . . . . . . . . . . . . . . . . . . . . . 249. Limestone, gray-blue, massive ........................ . . 248. Marl, yellow, very fossiliferous . . . . . . . . . . . . . . . . . . . . . . . . . . 247. Limestone, argillaceous, gray, nodular, weathers light gray to yellowish, with interbeds ofmassive, brownish gray limestone . . . . . . . . . . . . . . . . . . . . . . . 1846. Limestone, purple-gray, massive, thick-bedded, fossiliferous, weathers blue-gray . . . . 48TOTAL, COROR FORMATION: 147 METERS

RoMIR6N FORMATION45. Limestone, dark gray, massive, with interbeds of green, splintery shale . . . . . . . . 1244. Shale, dark brown, laminated, crumbly, fossiliferous. . . . . . . . . . . . . . . . . 843. Shale, green, brown, or yellow, laminated, soft, friable, with thin interbeds of nodular,richly fossiliferous (Acanthoceras sp., Lissoniceras mermeti, Exogyra olisiponensis, Exo-

gyra polygona), iron-stained, yellowish and brownish argillaceous limestone.46TOTAL, ROMIR8N FORMATION: 66 METERS

MUJARRiN FORMATIONCULEBRA MEMBER42. Limestone, very argillaceous; the top is a coarsely nodularsurface.1141. Limestone, gray, massive, thick-bedded, weathers dark gray . . . . . . . . . . . . . 2540. Limestone, argillaceous, white, laminated ...... . . . ... . . . . . . . . . 239. Limestone, very argillaceous, gray, nodular . . . . . . . . . . . . . . . . . . . . 4538. Marl, light gray, weathers white . . . . . . . . . . . . . . . . . . . . . . . . . 3TOTAL, CULEBRA MEMBER: 86 METERSCHORO MEMBER37. Limestone, gray, nodular, fossiliferous (Exogyra cf. ponderosa), weathers light gray . . 6536. Limestone, gray,laminated.9...................... ..35. Shale, white to yellowish, with interbeds of gray massive limestone . . . . . . . . 1234. Limestone, gray, laminated .1.0....... . .. . . . .. . . . . . . . .

.. 1233. imestone, silty, white, friable, laminated ..... . . . .. .. . . . . .. . 1032. Limestone, argillaceous, gray, nodular, weathers light gray . . . . . . . . . . .

. . 2531. imestone, bluish gray, massive, thick-bedded, ridge-forming. . . . . . . . . . .

. . 3230. Limestone, grayish blue, massive, thick-bedded, fossiliferous (Exogyra. cf. ponderosa),contains chert nodules. Ten meters above the base, there is a 20-centimeter thick bedof darkchert.63TOTAL, CHORO MEMBER: 221 METERS

TOTAL, MUJARR16NFORMATION: 307 METERSYUMAGUAL FORMATION29. Limestone, argillaceous, gray, nodular, weathers white . . . . . . . . . . . . . 13228. Shale, green, laminated . . . . . . . . . . . . . . . . . . . . . . . . . . . 227. Limestone, argillaceous, gray, thick-bedded, weathers white ..626. Shale, green, finely bedded . . . . . . . . . . . . . . . . . . . . . . . . .

25. Limestone, very argillaceous, marly, nodular, fossiliferous (Exogyra mermeti) . . . .204

VOL. 108410


METERS24. Quartz-sandstone, light gray to white, medium-grained, cross-bedded, friable, yellow-

weathering, includes thin beds of darkchert. .. . . . . . . 523. Shale, quartz-siltstone, and quartz-sandstone, soft, yellowish-weathering; the sandstone is

cross-bedded..................... ... . . . .....71

22. Limestone, argillaceous, very fossiliferous . . . . . . . . ..

. . . . . . . . .. . 2

21. Shale, quartz-siltstone and quartz-sandstone, finely interbedded . . . . . . . . . . . 3220. Limestone, gray, very fossiliferous (Ostrea, scyphax) . . . . . . . . . . . . . . . . 119. Shale, yellow, finely laminated............... ......... .

3018. Limestone, dark brownish, nodular, fossiliferous (Ostrea scyphax), weathers bluish gray . . 1517. Quartz-siltstone, yellow, finely laminated . . . . . . . . . . . . . . . . . . . . . 3016. Limestone, bluish gray, thick-bedded, fossiliferous (Ostrea scyphax, Trigonia sp.), with

chert nodules and a few interbeds of yellow shale . . . . . . . . . . . . . . . . 815. Shale, silty, yellow, laminated, contains Lingula . . . . . . . . . . . . . . . . . 614. Limestone, gray, massive ...................... . 213. Shale, black, thin-bedded, with some interbeds of nodular limestone. . . . . . . . . . 812. Limestone, gray, nodular, thick-bedded .... . . . . . . . . . . . . . . . . . . 2

TOTAL, YUMAGUAL FoRMATION: 538 METERS

PARIATAMBO FORMATION11. Limestone, slightly bituminous, yellowish and brownish, finely interbedded with grayish

black, slightly bituminous shale.. . . . . . . . . . . . . . . . . . . . . . . 152TOTAL, PARIATAMBO FORMATION: 152 METERS

CHULEC FORMATION10. Limestone, gray, thin- to medium-bedded, nodular .... . . . . . . . . . . . . . 479. Limestone, bluish gray, massive, with interbeds of light gray, medium- to thin-bedded,

nodular, soft marl and limestone.. . . . . . . . . . . . . . . . . 1. . . .. 258. Shale, bluish black, splintery . 9. . ....................................... ...

3

7. Marl, yellow, massive.3..... . . . . . . . . . . . . . . . . . . . . . . . . 36. Shale, blue-gray, laminated ..... . . . . . . . . . . . . . . . . . . . . . 235. Limestone, black, thick-bedded, massive, weathers bluish gray, with interbeds of brownish

yellow, laminated, soft marl ..... . . . . . . . . . . . . . . . . . . . . . 254. Shale, brownish, with interbeds of nodular, rusty, argillaceous limestone.. . . . . . 253. Limestone, bluish gray, massive, thick-bedded, fossiliferous, weathers dark gray . . . 72. Marl, brownish yellow, laminated, very fossiliferous (Knemiceras sp., Enallaster peruanus),

with interbeds of nodular, ledge-forming, brownish limestone.. . . . . . 491. Marl, brownish gray, laminated ................ . . 17+

TOTAL, CEULEC FORMATION: 330+ METERS

SECTION 5. CAJAMARCA

Section (fig. 17) measured from 500 meters north of Bafios del Inca, 6 kilometers west of thecity of Cajamarca, to Quebrada Otuzco, 8 kilometers northeast of Cajamarca. It includes thetypes of the Inca, Yurnagual, Mujarruin, Romir6n, Cofior, and Cajamarca formations.

CELENDiN FORMATION METERS

146. Limestone, slightly argillaceous, gray, medium-bedded . . . . . . . . . . . . . . 10+145. Shale, calcareous, yellowish white, fossiliferous (great numbers of Hemiaster fourneli) . . 20144. Shale, calcareous, yellow, crumbly, richly fossiliferous (Buchiceras bilobatumn, Heterotissotia

0 peroni, H. bucheri, several species of Barroisiceras) . . . . . . . . . . . . . . . . 61TOTAL, CELENDIN FORMATION: 91+ METERS

CAJAMARCA FORMATION

143. Limestone, argillaceous, yellowish gray, nodular ... . ........ .. . .. 39142. Limestone, dark gray, very massive, thick-bedded . . . . . . 169

141. Shale, brownish yellow, crumbly, fossiliferous (Coilopoceras newelli) .... . . .. .. 10

1956 411.


.1

FIG. 17. Cajamarca stratigraphic section.

VOL. 108412


METERS140. Limestone, dark bluish gray, massive, thick-bedded, karstic, with a few thin-bedded,

platy, limestoneinterbeds.. . . . . . . . . . . . . . . . . . . . 161139. Limestone, dark gray, lithographic, very massive, thick-bedded.. . . . . 88138. Limestone, dark gray, massive, with interbeds of light gray, argillaceous limestone . . . 59137. Limestone, argillaceous, light gray, splintery . . . . . . . . . . . . . . . . . . . . 10136. Shale, calcareous, light gray.. . . . . . . . ... . . .............

16135. Limestone, dark gray, thick-bedded, with interbeds of argillaceous, splintery limestone . 5TOTAL, CAJAMARCA FORMATION: 557 METERS

CoSOR FORMATION134. Limestone, light gray, splintery, friable . . . . . . . . . . . . . . . . . . . . . . 12133. Shale, yellowish to light gray, friable, fossiliferous (Coilopoceras jenksi, Mammites afer,

Hoplitoides inca, Inoceramus labiatus, Orthopsis titicacana), with thin interbeds of argil-laceous limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

132. Limestone, dark gray, thick-bedded, fossiliferous (Orthopsis titicacana). . . . . . . . 1131. Shale, light gray, finely laminated, friable . . . . . . . . . . . . . . . . . . . . . 8130. Limestone, massive, dark gray . I129. Shale, very calcareous, light gray, crumbly. . . . . . . . . . . . . . . . . . . . . 23128. Limestone, argillaceous, light gray, thick-bedded.. . . ............. . 2TOTAL, COROR FOR1iATION: 61 METERS

RoMIR6N FORMATION127. Shale, rusty and brownish yellow, soft, very fossiliferous (Acanthoceras sp., Exogyra olisipo-

nensis), with few and thin intercalations of brown limestone. This unit makes a topo-graphic low and is largely covered with soil.. . . . . . . . . . . . . . . . . 3

TOTAL, ROMIR6N FORMATION: 83 METERS

MUJARRfCN FORMATIONCULEBRA MEMBER126. Limestone, argillaceous, nodular, thick-bedded, with thick interbeds of light gray, chalky,

very fossiliferous (Acanthoceras sp., Exogyra africana, E. olisiponensis), argillaceouslimestone ................................. . . . . . . . . . . . . . . 72

125. Limestone, argillaceous, nodular, light gray, fossiliferous, with interbeds of gray marl . 12124. Limestone, marly, nodular, soft ..... . . . . . . . . . . . . . . . . . . . . 21TOTAL, CULEBRA MEMBER: 105 METERS

CHORO MEMBER123. Limestone, dark bluish gray, thick-bedded, ledge-forming, massive . . . . . . . . . 3122. Limestone, dark gray, thick-bedded, nodular, fossiliferous (Exogyra cf. ponderosa). . . . 22121. Limestone, dark bluish gray, thick-bedded, compact, massive, contains E. cf. ponderosa. . 4120. Limestone, dark bluish gray, thick-bedded, wavy-bedded to nodular, ledge-forming . . . 15119. Quartz-siltstone, calcareous, brownish yellow, thin-bedded . . . . . . . . . . . . 4118. Limestone, gray, massive, thick-bedded, nodular ... .... ... ..... ... . 20

117. Limestone, grayish brown, thick-bedded, compact, with thin interbeds of light gray,

laminated, calcareous quartz-siltstone .... . . . . . . . . . . . . . . . . . . 11

116. Limestone, dark gray, compact, ridge-forming ............ . . . . ... 33

115. Limestone, dark gray, thick-bedded, massive, with interbeds of light gray, very fossiliferous(E. cf. ponderosa) limestone .... . . . . . ................. 49

114. Limestone, brownish gray, massive,compact.29TOTAL, CHORO MEMBER: 190 METERSTOTAL, MUJARR§N FORMATION: 295 METERS

YUMAGUAL FORMATION113. Limestone, very argillaceous, shaly, wavy-bedded, nodular, fossiliferous . . . . . . . 18112. Limestone, dark gray, thick-bedded, massive, nodular, with interbeds of brownish yellow,

fossiliferous marl.21111. Limestone, very argillaceous, marly, light gray to light brownish gray, nodular, soft, fossilif-

1956 413


METERSerous (Paraturrilites lewesiensis, Skarpeiceras occidentale, Exogyra mermeti).10

110. Limestone, dark gray, nodular, massive, thick-bedded, with interbeds of argillaceous,chalky, coquinoid (E. mermeti), soft limestone.22109. Shale, calcareous, lightbrown. 15

108. Limestone, very argillaceous, light gray to light brownish gray, wavy-bedded to nodular,fossiliferous ..... . . . 14

107. Limestone, gray, massive, thick-bedded,nodular. 5106. Limestone, very argillaceous, marly, light brownish gray, soft, some beds are almost

coquinas of E. mermeti . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19105. Limestone, dark gray, thick-bedded, massive, with interbeds of soft, nodular, marly, fossil-iferous (E. mermeti), argillaceous limestone. . . . . . . . . . . . . . . . . . . . 40

104. Limestone, argillaceous, soft, yellowish green to whitish gray, with thin interbeds of com-pactlimestone...............................3103. Limestone, dark gray, nodular, massive, with interbeds of light gray, soft, coquinoid (E.mermeti) marl .. . ............................. 15102. Limestone, grayish black, nodular, fossiliferous ........... . .... ... 154

101. Limestone, dark gray, massive, thick-bedded, nodular, with interbeds of fossiliferous(Engonoceras sp. indet., Exogyra mermeti), argillaceous limestone . . . . . . . . . . 46

100. Limestone, dark gray, with intercalations of chert . . . . . . . . . . . . . . . . . 399. Limestone, argillaceous, nodular, wavy-bedded . . . . . . . . . . . . . . . . . . . 798. Shale, black to brown, laminated, splintery . . . . . . . . . . . . . . . . . . . . 1697. Limestone, argillaceous, brownish, thin-bedded, soft, with a thin bed of brownish green

phosphate at the top . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1196. Limestone, argillaceous, brownish gray, thick-bedded, weathers yellow . . . . . . . . 495. Limestone, argillaceous, marly, shaly, light gray to grayish yellow, soft, with few inter-

calations of compact, dark gray limestone . . . . . . . . . . . . . . . . . . . . 1494. Limestone, silty, light gray, wavy-bedded to nodular, with coquinoid beds of Ostreascyphax.1493. Limestone, very argilIaceous, chalky, nodular, grayish yellow, soft, very fossiliferous . . 1892. Limestone, light gray, nodular, thick-bedded with few interbeds of argillaceous limestone . 1291. Quartz-siltstone, calcareous, brownish yellow, interbedded with fossiliferous, light graylimestone. 1090. Limestone, gray, wavy-bedded, fossiliferous (Ostrea scyphax, Oxytropidoceras sp.) . . . . 3089. Limestone, argillaceous, dark gray, nodular, with interbeds of black and brown, soft shale. 23TOTAL, YUMAGUAL FORMATION: 546 METERS

PARIATAMBO FORMATION88. Limestone, grayish black, blocky, hard, medium-bedded, with thin intercalations of chert. 1787. Limestone, bituminous, dark gray, thin-bedded, fossiliferous (Dipoloceras sp.), with inter-beds of black to yellowish brown, calcareous and bituminous shale . . . . . . . . . 6286. Shale, calcareous, bituminous, black, thin-bedded, with interbeds of compact, black lime-stone.1585. Limestone, bituminous, gray, massive, shaly, concretionary, fossiliferous (Oxytropidocerascarbonarium, Venezoliceras venezolanum), bituminous marl.1684. Shale, dark gray, bituminous, thin-bedded, fossiliferous (0. carbonarium, Lyelliceras ulrichi,Inoceramus concentricus). 8

83. Limestone, bituminous, dark gray, massive, fossiliferous . . . . . . . . . . . . . . . 282. Limestone, slightly argillaceous, bituminous, dark yellowish brown, blocky, thin-bedded,with few intercalations of dark brownish gray calcareous shale.1281. Limestone, strongly petroliferous, dark gray, thick-bedded, massive, sparsely fossiliferous. 5

TOTAL, PARIATAMBOFORMATION: 137 METERSCHULECFORMA'TON .... .880. limestone, dark gray, massive, thin-bedded, with interbeds of calcareous shale. . . 879. Shale, calcareous, browmish yellow, laminated, with interbeds of nodular, gray limestone 2578. Limestone, compact, medium-bedded

77. Covered; apparently it is soft marl.The interval is occupied by the Quebrada Pulluicana 111

414 VOL., 108


METERS76. Limestone, argillaceous, shaly, nodular, thin-bedded, weathers greenish white .3675. Limestone, argillaceous, fossiliferous (Exogyra aquita, Liopistha gigantea) . . . . . . 474. Limestone, argillaceous, dark gray, thin-bedded, somewhat nodular, fossiliferous (Kne-

nsiceras sp., Parengonoceras sp., Liopistha gigantea), with interbeds of yellowish white,crumbly, calcareous shale ...... . . . . . . . . . . . . . . . . . . . . . 41

73. Limestone, dark gray, massive, weathers bluish gray . . . . . . . . . . . . . . . . 372. Limestone, argillaceous, marly, dark gray, nodular, thin-bedded, weathers white, with few

interbeds of compact, gray limestone . . . . . . . . . . . . . . . . . . . . . . 2271. Shale, calcareous, greenish and whitish gray, soft, fossiliferous (Knemiceras syriacum,

Parengonoceras guadaloupaeforme, Liopistha gigantea), with a few interbeds of massivelimestone.17

70. Shale, purple-red to yellowish, laminated, splintery, fossiliferous (Knemiceras attenuatum,K. raimondii), with thin interbeds of nodular, yellowish brown, argillaceous limestone . 20

69. Shale, calcareous, laminated, splintery, purple-red to greenish, fossiliferous . . . . . . 3268. Limestone, very argillaceous, dark brownish gray, nodular, thin-bedded, fossiliferous

(Knemiceras sp., gastropods), weathers white . . . . . . . . . . . . . . . . 767. Shale, calcareous, black to dark brown, laminated, fossiliferous. 1566. Limestone, argillaceous, dark gray, nodular, thin-bedded, fossiliferous, weathers white 1965. Marl, chalky, thin-bedded, with thin interbeds of nodular, dark gray shale.. . . . . 2764. Limestone, argillaceous, nodular, with a few interbeds of massive, dark gray limestone . 1163. Limestone, argillaceous, chalky, with interbeds of calcareous shale. 1362. Marl, chalky, thin-bedded, nodular, weathers white, with thin interbeds of dark graylimestone.29

61. Marl, dark greenish gray, soft, splintery, fossiliferous, with few intercalations of brownishgray, massive, rusty, ledge-forming limestone.. . . . . . . . . . . . . . . . . 93

60. Limestone, argillaceous, chalky, yellowish gray.................. . 759. Marl, yellowish to brownish, splintery, thin-bedded, soft, fossiliferous .. . ....... 1158. Limestone, yellowish brown to brownish gray, massive, thick-bedded, very fossiliferous

(Knemiceras raimondii, K. attenuatum, Parengonoceras sp., Prolyelliceras peruvianum,Douvilleiceras monile) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


INCA FORMATION57. Limestone, rusty brown, massive, with interbeds of soft, yellowish brown shale . . . 17

56. Quartz-siltstone, ferruginous, dark brown, with interbeds of calcareous, ferruginous shaleand quartz-sandstone . . . . . . . . . . . . . . . . . . . . . . ... . . . . . 10

55. Limestone, greenish brown, fossiliferous, with interbeds of calcareous, ferruginous shale . 754. Quartz-siltstone, ferruginous, brownish red .... . . . . . . . . . . . . . . . . 553. Limestone, gray, arenaceous .... . . . . . . . . . . . . . . . . . . . . . . . 452. Limestone, reddish brown, arenaceous, with interbeds of soft, fossiliferous, yellowish brown

marl and shale . . .......... .......... .......... ... 10

51. Shale, yellowish to greenish brown, splintery, with thin interbeds of ferruginous quartz-siltstone ............-.-.-.-.. - - - - . - . . ... . . . . . . ............

50. Limestone, gray, slightly nodular, fossiliferous (Parahoplites quilla, Pterotrigonia tocai-maana, .Buchotrigonia abrupta, Yaadia hondaana, Ptychomia robinaldina). . . . . . . 2

49. Marl, ferruginous, rusty yellow .I..... . . . . . . . . . . . . . . . . . . .

48. Limestone, arenaceous, oolitic, rusty brown, very fossiliferous (Exogyra aguila) . . . . . 147. Marl, ferruginous, with interbeds of quartz-siltstone . . . . . . . . . . . . . . . . 1046. Limestone, arenaceous, rusty brown, glauconitic, ferruginous, thick-bedded . . . . . . 445. Conglomerate of angular cobbles of brownish gray limestone in a ferruginous, rusty brown,

calcareous matrix . . . . . . . 2. . . . I I . . . . . . . . . . . . ...2TOTAL, INCA FORMATION: 80 METERS

DIscoNFORMITYGomLARISQUISGA FORMATION44. Shale, light gray, soft, interbedded with a white, hard quartz-sandstone . . . . . .

. 3043. Quartz-siltstone, light gray, with interbeds of cross-bedded quartz-sandstone - . . . . . 11

1956 415


METERS42. Quartz-sandstone, white to pale red, medium- to coarse-grained, cross-bedded, massive 741. Shale, yellowish to bluish, laminated, soft, with few interbeds of quartz-siltstone . . 9140. Shale, pale blue to purple, laminated, soft, contains poorly preserved plant remains. 3239. Quartz-sandstone, light gray, medium-grained, to pebbly, cross-bedded, weathers dark red. 938. Quartz-siltstone, light gray, soft, with interbeds of bluish shale.1837. Quartz-sandstone, white to reddish, coarse-grained to pebbly, cross-bedded, medium-bedded.3036. Quartz-siltstone, purple-red, medium-bedded, with interbeds of soft, bluish and greenishshale. 935. Quartz-pebble conglomerate, white to yellowish, thick-bedded, cross-bedded . . . . . . 934. Quartz-siltstone, white to brownish, thin-bedded, weathers rusty red.3333. Quartz-pebble conglomerate, white to reddish, cross-bedded, thick-bedded, massive . . 932. Quartz-siltstone, white to reddish, with interbeds of soft, varicolored shale .1131. Quartz-sandstone, white, coarse-grained, cross-bedded, hard - . . .1430. Shale, varicolored, thin-bedded, soft, with few interbeds of quartz-sandstone . 2329. Quartz-sandstone, white to pale red, thin-bedded, weathers brown, with some shale inter-calations.1228. Quartz-sandstone, coarse-grained, cross-bedded, massi've ............ . . 3027. Quartz-sandstone, white to pale red, cross-bedded, medium-bedded.4226. Quartz-sandstone, white to light gray, coarse-grained to pebbly, hard, thick-bedded,weathers rusty red, forms a scarp . . . . . . . . . . . . . . . . . . . . . . . 6125. Quartz-sandstone, white to yellowish brown, medium- to coarse-grained, medium-bedded,massive, weathers reddish brown.97TOTAL, GOYLLARISQUISGA FORMATION: 578 METERS

CARHUAZ FORMATION24. Covered; probably of soft shale. 16023. Quartz-sandstone, white to yellow, cross-bedded . . . . . . . . . . . . . . . . . . 922. Shale, yellow, soft.921. Quartz-sandstone,white. 220. Shale, bluish to purple, soft.3719. Quartz-siltstone, yellowish brown, with a few interbeds of quartz-sandstone . . . . . . 618. Shale, yellowish to greenish, thin-bedded, soft.1217. Quartz-sandstone, yellowish to reddish white, medium-grained, cross-bedded, massive . 9Shale, varicolored, soft, with a few thin interbeds of micaceous, pale red, quartz-siltstone 1215. Quartz-sandstone, white to yellowish brown, medium-grained, cross-bedded, lenticular,contains plant remains.21

Shale, yellowish to reddish, soft, with thin intercalations of rusty quartz-siltstone . . 21Quartz-sandstone,reddish, cross-bedded, lenticular, medium-bedded, massive .16Shale, yellow to dark red, soft, containls plant remains, with interbeds of white, cross-bedded quartz-siltstone.44Quartz-sandstone, white to yellowish, contains plant remains, forms a ridge . . . . . . 7

10. Shale, dark yellow to brownish gray, slightly calcareous,contains plant remains, with a fewinterbeds ofquartz-siltstone. 279. Shale, varicolored, soft, with thin intercalations of ironoxide.. 248. Quartz-sandstone,white to brownish, medium-grained,cross-bedded, lenticular, weathersrusty brown ..........awahr

7.Shale, varcolored, soft, crumbly, contains plant remains, with interbeds of ferruginous

6.Quartz-sandstone.38larou6. Quartz-sanzdstone,calcareous, white to brownish, medium-grained, cross-bedded . . .

125. Shale, whitish

grayto purple, soft, with interbeds of calcareous quartz-sandstone . . 274. Shale, varicolored, soft . . . . . . . .-...... 73.Quartz-siltson slightlycalcareous, brownish, cross-bedded, thin- to medium-bedded,with oscilelationripplemarks, fossiliferous (Paraglauconia strombiformis), with interbedsOf foSsiliferous (plant remains) shale.g s182. Shale, varicolored, soft, thin-bedded, concretionary fossiliferous.(feh-ae gasroodand pelecypods) rous(fresh-wter.gastr..18

416 VOL. 108


METERS1. Shale, light gray to purplish gray, soft, thin-bedded, contains badly preserved plant re-

mains, and fresh-water gastropods, has a few interbeds of rusty, calcareous quartz-sand-stone...15+

TOTAL, CARHUAZ FORMATION: 556+ METERs

SECTION 7. TEMBLADERA

Composite section (fig. 18); the lower Goyllarisquisga formation was measured just northof Monte Grande, 45 kilometers northeast of Pacasmayo, on the Cajamarca to Trujillo road.The rest of the section was measured from 6 kilometers north of Tembladera to the outskirtsnorth of this place. Tembladera is on the north side of the Jequetepeque River, 5 kilometerseast of Monte Grande.CAJAMARCA FORMATION29. Limestone, grayish black, massive, thick-bedded, weathers light gray . . . . . . . . .

28. Limestone, grayish black, thin- to medium-bedded, fossiliferous (Ostrea sp.), weathers lightgray . . . - - - - . - . - - . - . - . . - - . . - . . . . .

TOTAL, CAJAMARCA FoRMATION: 111 METERS

[ETERS74

37

TURONIAN - -OCoilopoceras newelli zone

Coilopoceras jenksi zone -

Acanthoceras chasca zone T T..........

Exogyra africanazoneGENOMANIAN-.

Exogyra c£ ponderosa zone

Paraturrifttes lewesiensis zone-

__ --_- -

_ __w__

Ja T~ .~

Ostrea scyphax zone

Oxyfropidoceras carbonarium zone

ALBIAN --- -

Knemiceras raimondii zone

Parchoplites nicholsoni zone

APTIAN

--?--P---@ M tvT|;*J

NEOCOMJAN

GATAMARGA FM4fl'QUILLQUUAN GROUP(undiff.)

(281 m.)

UNNAMED

SHALESAND

SANDSTONES(678u)

UNNAMED THIOKBEDDED LIMES1VNE

(715 in.)

GOYLLARISQUISGA-Ls irc IrA

FIG. 18. Tembladera stratigraphic section.

-

4171956

m


QUILLQUIRAN GROUP METERS27. Marl, nodular, grayish green, fossiliferous (Coilopoceras jenksi, Pseudoaspidoceras reesidei,Inoceramus labiatus, Exogyra sp., Hemiaster fourneli), interbedded with yellowish white,soft shale.. . . . . . . . . . . . . . . . . . . . 4. . . . . . . . . . . . 4526. Shale, orange-brown, laminated, with thin interbeds of greenish brown quartz-siltstone . 3025. Marl, orange-yellow, nodular, with interbeds of dark gray limestone.. . . . . . . . 3024. Shale, yellow, laminated, soft, with interbeds of dark gray, richly fossiliferous (Broggiicerashumboldti, B. oissoni, Thomasites fischeri), slightly silty limestone.. . . . . . . . . 3323. Shale, pale greenish yellow, crumbly, with thin interbeds of blocky, fossiliferous, graylimestone ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2222. Shale, yellow, friable, thick-bedded, with interbeds of nodular, fossiliferous (Bxogyra afri-

cana, E. olisiponensis), light gray limestone.. . . . . . . . . . . . . . . . . . 121ToTAL, QUILLQUIRAN GROUP: 281 METERSUNNAMED BEDS21. Shale, light gray to yellow, thick-bedded, with interbeds of bluish black limestone . . 9120. Shale, yellow, laminated, crumbly.1919. Limestone, black, massive, weathers light gray, with interbeds of light gray quartz-silt-

stone.3018. Quartz-siltstone, silicified, white to yellowish brown, laminated, with interbeds of shale 10017. Quartz-sandstone, silicified, reddish, massive, thick-bedded. . . . . . . . . . . . . . 1516. Quartz-siltstone, white to yellowish brown, laminated, crumbly, with interbeds of shale . 9115. Quartz-sandstone, brownish, silicified . . . . . . . . . . . . . . . . . . . . . . 6514. Limestone, black, massive, thick-bedded, weathers dark gray.. . ... .. . . . . . 413. Shale, yellow to light brown, laminated, crumbly, soft ..269TOTAL, UNNAMED BEDS: 684 METERS

UNNAMED BEDS12. Limestone, black, massive, thick-bedded, with silicified interbeds . . . . . . . . . . . 42611. Limestone, black to gray, thin-bedded to laminated, weathers light gray .13010. Limestone, black to gray, massive, thick-bedded, fossiliferous (Exogyra minos, Trigonioarca

sp., Cucullaea sp.), weathers brownish gray, has silicified interbeds.159TOTAL, UNNAMED BEDS: 715 METERSGOYLLARISQUISGA FORMATION

9. Quartz-siltstone and shale, brick-red, laminated .. 258. Quartz-siltstone and quartz-sandstone, white to light brown, thick-bedded, with a few thinintercalations of shale. . . ..877. Quartz-sandstone, white to brownish, medium-grained, thick-bedded, cross-bedded,weathers reddish brown.1156. Quartz-siltstone and shale, brown, laminated, weathers greenish and brownish, hasa fewinterbeds of quartz-sandstone. 1385. Quartz-sandstone, light gray to brownish, massive, cross-bedded, medium- to thick-bedded,weathers brown.954. Quartz-sandstone and quartz-siltstone, light brown, thin- to medium-bedded.323. Quartz-sandstone, light-brown, medium-grained, medium-bedded .... . . . . . .. 28

2. Quartz-siltstone, black, with a few interbeds of quartz-sandstone . . . . . . . . . . 481. Quartz-sandstone, light brown to greenish, fine- to medium-grained, cross-bedded . . . 22+TOTAL, GOYLLARISQTUISGA FORMATION: 590+ METERS

SECTION 8. TAMBERIASection measured just west of Hacienda Tamberia, at the junction of the Cajabamba andCajamarca rivers.

PARIATAMBO FORMATION13. Limestone, grayish black,thin-bedded, platy, poorly exposed. . . . . . . . . . . . . 35+TOTAL, PARIATAMBO FORMATION: 35+ METERS

'418 VOL. 108


CHULEC FORMATION METERS12. Limestone, gray, thick-bedded, with interbeds of light gray, fossiliferous marl . . . 8511. Limestone, grayish, thin-bedded, nodular, fossiliferous (Knemiceras sp., Enallaster sp.),

weathers light brownish gray, has a few interbeds of splintery, calcareous shale . . . 7610. Marl, light gray, nodular, fossiliferous (Knemiceras raimondii, Enallaster sp.), with inter-

beds of gray, massive limestone . . . . . . . . . . . . . . . . . . . . . . . . 839. Limestone, greenish gray, massive, compact, thick-bedded, fossiliferous (trigonids, exo-

gyroids), weathers brownish gray ..... . . . . . . . . . . . . . . . . . . . 20TOTAL, CHULEC FORMATION: 264 METERS

INCA FORMATION

8. Shale and quartz-siltstone, slightly ferruginous, calcareous, greenish gray, medium-bedded,weathers dark brownish red . . . . . . .. . . . . . . . .. .... . . . .. 44

7. Limestone, brownish, massive, thick-bedded, fossiliferous, weathers yellowish and reddish. 116. Shale and quartz-siltstone, calcareous, brownish and greenish, very fossiliferous (several

species of Parahoplites, Desmoceras chimuense, Pterotrigonia tocaimaana, Buchtrigornaabrupta, Yaadia hondaana), weathers light reddish brown.. . . . . . . . . . . . 16

5. Quartz-sandstone, white, compact, with a few interbeds of shale.. . . . . . . . . . 804. Shale, slightly calcareous, brownish green .... . . . . . . . . . . . . . . . . . 123. Limestone, arenaceous, fossiliferous .... . . . . . . . . . . . . . . . . . . . . 22. Shale, quartz-siltstone and quartz-sandstone, slightly calcareous, glauconitic, reddish

brown 5TOTAL, INCA FORMATION: 218 METERS

GOYLLARISQUISGA FORMATION

1. Quartz-sandstone, white, medium- to coarse-grained, massive, thick-bedded, weathersreddish brown.80+

TOTAL, GOYLLARISQUISGA FORMATION: 80+ METERS

SECTION 9. CRISNEJAS

Section (fig. 19) measured along the south side of the Crisnejas River, from Tingo, at thejunction of the Crisnejas and Marafo6n rivers, to Santa Rosa.CRETACEOUSCAJAMARCA FORMATION METERS61. Limestone, light gray, medium-bedded, with a few interbeds of shale . . . . . . . . . 215+60. Limestone, light gray, massive, medium-bedded, weathers dark gray . . . . . . . . . 6359. Marl, green to white, nodular, fossiliferous . . . . . . . . . . . . . . . . . . . . 1058. Marl, brownish yellow, nodular. . . . . . . . . . . . . . . . . . . . . . . . . . 11757. Shale, light green.. . . . . . . . .. ........ ...... . . 256. Limestone, medium brownish gray, massive, thick-bedded, weathers bluish gray . . . . 80

TOTAL, CAJAMARCA FORMATION: 487+

ROMIR6N FORMATION

55. Shale, calcareous, blue to green, soft, fossiliferous (Exogyra olisiponensis).. . . . . 2154. Shale, calcareous, bluish gray to green, nodular, laminated, with interbeds of massive, yel-

low, argillaceous limestone . . . . . . . . . . . . . . . . . . . . . . . . . . 1053. Marl, brownish and bluish white, nodular, fossiliferous (Inoceramus sp., Ostrea sp., Orthopsistiticacana).8

52. Shale, calcareous, bluish to greenish gray, friable, with interbeds of nodular marl . . . . 8TOTAL, ROMIR6N FORMATION: 47 METERS

MUJARR6N FORMATION51. Limestone, yellowish gray, thick-bedded, massive, weathers brownish gray . . . . . . 3650. Shale, calcareous, greenish and brownish gray, medium-bedded . . ....149. Limestone, yellowish gray, thick-bedded.. . . . . . . . . . 105

1956 419


METERS48. Limestone, brownish gray, massive, thick-bedded, scarp-formning, weathers light brownish

gray ................................... . 79TOTAL, MUJARRTN FORMATION: 301 METERS

ROSA FORMATION47. Limestone, argillaceous, light brown to greenish white . . . . . . . . . . . . . . 13

FIG. 19. Crisnejas stratigraphic section.

420 VOL. 108


METERS46. Shale, calcareous, greenish white, laminated, with a few interbeds of brown, nodular, argil-

laceous limestone. 4445. Limestone, arenaceous, dark brown, massive, weathers rusty brownish yellow, with inter-

beds of nodular, greenish white marl . . . . . . . . . . . . . . . . . . . . . 3144. Quartz-siltstone, whitish, thin-bedded .. ..................... 6343. Limestone, brownish gray, fossiliferous (Echinobrissus sp., Bothriopygus sp., Holectypus

sp.), weathers rusty dark brown, with interbeds of light gray, argillaceous limestone . 842. Shale, bluish gray, laminated, with interbeds of massive, argillaceous limestone . . . . 8041. Shale and quartz-siltstone, greenish and bluish, soft.7040. Quartz-siltstone and quartz-sandstone, red, cross-bedded . . . . . . . . . . . . . . 9539. Quartz-sandstone, deep red, soft, cross-bedded.1338. Conglomerate of polished and varnished dreikanter cobbles in a coarse, deep red matrix;

thick-bedded.................... ......... ... 1837. Quartz-sandstone, deep red, coarse-grained, thick-bedded, massive.5036. Quartz-siltstone, deep cherry-red, soft . . . . . . . . . . . . . . . . . . . . . 4735. Quartz-sandstone, red, coarse-grained, massive, cross-bedded, with thin interbeds of con-

glomerate in the upper part.. . . . . . . . . . . . ..7. . . . . . . . .. . 734. Conglomerate of unassorted, rounded pebbles and cobbles of quartzite in a scanty, red

sandymatrix. 1633. Covered. The float is of brownish red splintery limestone ..4832. Shale and quartz-sandstone, whitish green and purple . . . . . . . . . . . . . . . . 4631. Quartz-sandstone, calcareous, white, cross-bedded, thin-bedded . . . . . . . . . . . 1230. Shale and marl, light gray, nodular . . .. . . . . . 2729. Shale, deep red,soft.. 328. Quartz-sandstone, yellowish, medium-grained, friable, cross-bedded, lenticular, medium- to

thick-bedded, weathers light brown . . . . . . . . . . . . . . . . . . . . . . . 59TOTAL, ROSA FORMATION: 750 METERS

DISCONFORMITYCRISNEJAS FORMATION27. Limestone, tan, massive, thick-bedded, the top is a deeply channeled and weathered sur-

face...... ...................... . 1226. Limestone, cream, thin-bedded, fossiliferous (Oxytropidoceras sp., Inoceramus sp.), weatherswhite..12

25. Limestone, tan, massive, thick-bedded, ridge-forming, weathers brown . . . . . . . . 9324. Limestone and marl, cream to tan, thick-bedded, becomes more calcareous upward . . . 7523. Limestone, light tan, massive, thick-bedded, weathers brown.1622. Marl, light olive gray, fossiliferous, weathers white, with interbeds of light yellowish brown,

thick-bedded limestone.. . . . . . . . . . . . . . . . . . . . . . . . . . . 3321. Shale, slightly calcareous, greenish white to light gray, nodular, fossiliferous (Exogyra cf.

boussingaulti, Holectypus planatus), with a very few thin interbeds of massive, yellowishbrown limestone.103

20. Shale, bluish and purple, laminated, splintery, soft, with interbeds of light gray, nod-ular, fossiliferous (Echi-nobrissus sp., Bothriopygus sp., HolectyPus planatus, Enal-laster peruanus, Yaadia hoindaana, Pholadomya sp., Ostrea cf. dieneri, Parengonoceraspernodosum), brown-weathering, argillaceous limestone.. . . . . . . . . . . . . 57

TOTAL, CRISNEJAS FORMATION: 401 METERS

GOYLLARISQUISGA FORMATION

19. Quartz-sandstone, whitish, slightly ferruginous, laminated, soft, weathers brownish andpurplish................................. . .

18. Quartz-sandstone, ferruginous, white, thick-bedded, weathers brownish . . . . . . . . 917. Quartz-sandstone, white, medium- to coarse-grained, cross-bedded, thin-bedded . . . . 4416. Quartz-sandstone, white, coarse-grained to pebbly, massive, cross-bedded, weathers brown-

ish 4815. Shale, purple and white, laminated. . . . . . . . . . . . . . . . . . . . . . . . 814. Quartz-sandstone, white to purplish, coarse-grained, thick-bedded, ridge-forming, weathers

19S6 421


METERSlight reddishbrown. 184

13. Quartz-sandstone, white to brownish, coarse-grained to pebbly, thick-bedded ..8812. Quartz-sandstone, white, soft, coarse-grained ................ . . . 9011. Shale, white to light purple, soft . . . . . . . . . . . . . . . . . . . . . . . . 1510. Conglomerate of rounded quartz pebbles . . . . . . . . . . . . . . . . . . . .. 309. Quartz-sandstone, white, coarse-grained to pebbly, soft, laminated, cross-bedded .... 258. Quartz-sandstone, white, coarse-grained, thick-bedded, lenticular, ridge-forming, weathers

reddish brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897. Conglomerate of quartz pebbles in a sandy matrix, fills channels in the underlying unit . . 1

TOTAL, GOYLLARISQUISGA FORMATION: 666 METERSUNCONFORMITYTRIASSICULIAcHfN FORMATION

6. Claystone, white, thin-bedded, with thin, calcareous, fossiliferous (Nevadites sp.) interbeds. 1115. Chert, ferruginous, massive, weathers reddish . . . . . . . . . . . . . . . . . . . 124. Limestone, dark brownish, massive, thick-bedded, ridge-forming, with abundant chert

nodules ...... . . . . . . . . . . . .. . . . . . . . . . . . . . .. 117TOTAL, ULIAcEfN FORMATION: 240 METERSDISCONFORMITYPALEOZOICMITU FORMATION

3. Shale and quartz-siltstone, purple, hard, thin- to medium-bedded . . . . . . . . . . 932. Shale, quartz-siltstone and quartz-sandstone, arkosic, tuffaceous, green, becomes more

argillaceous upward. Near the top, there are a few thin, fossiliferous (Avonia sp,, Derbyiasp., Crurithyris sp.), calcareous interbeds . . . . . . . . . . . . . . . . . . . . 132

1. Conglomerate of cobbles and pebbles of light green phyllite, quartz, and diorite in a matrixof dark green, arkosic quartz-sandstone . . . . . . . . . . . . . . . . . . . . . 350

TOTAL, MITU FORMATION: 575 METERS

SECTION 10. HUAYCOTSection measured along the road from Chicama to Huacraruco to Cajamarca, from 4 kilo-

meters west of Hacienda Huaycot, 7 kilometers north of Hacienda Sunchubamba, to CerroHuaugu6n.CAJAMARCA FORMATION METERS40. Limestone, light gray, massive, thick-bedded . . . . . . . . . . . . . . . . . . . 25+39. Limestone, argillaceous, nodular, shaly.1538. Shale, calcareous, brownish gray, fossiliferous.9037. Limestone, argillaceous, petroliferous, medium gray, shaly to nodular, weathers light gray,

with interbeds of dark gray, sublithographic, massive limestone . . . . . . . . . . 11636. Limestone, petroliferous, grayish black, sublithographic, thick-bedded, with few interbeds

of bluish marl ..... . . .... . .. . . .. . . . . .. . . . .. . . . 11435. Limestone, very argillaceous, bituminous, dark gray, nodular to shaly, fossiliferous (Coilo-

poceras), weathers light gray, has interbeds of dark gray, massive limestone . . . . . 10334. Limestone, bituminous, dark gray, massive, thick-bedded, weathers light gray . . . . . 4033. Limestone, very argillaceous, dark gray, nodular, shaly, weathers light gray, has interbeds

of massive limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68TOTAL, CAJAMARCA FORMATION: 571+ METERSQUiLLQUiIAN GRouP32.Covered... ......... . .... . . 200PULLUCANA GROUP31. Limestone, very argillaceous, dark bluish gray, nodular, wavy-bedded, thick-bedded,

VOL. 108422


METERSweathers light gray to yellowish . . . . . . . . . . . . . . . . . . . . . . . 76

30. Marl, bluish and brownish gray, shaly to nodular.1529. Limestone, dark gray, medium-bedded...8.. . . . . . ......... . . 828. Shale, calcareous, bluish gray to black, with a few thick interbeds of nodular marl . . 1627. Limestone, very argillaceous, dark gray, nodular to wavy-bedded, with a few interbeds of

massive, dark gray limestone . . . . . . . . . . . . . . . 5526. Limestone, bituminous, bluish gray to dark gray, massive, with intercalations of bituminous

shale 5425. Limestone, argillaceous, bituminous, dark gray, nodular, thick-bedded, with intercalations

of bituminous shale. 10624. Limestone, bituminous, bluish gray, massive, thick-bedded, prominent in the topography . 15623. Limestone, bluish gray, thin-bedded. 1022. Limestone, sublithographic, medium-bedded. 3521. Limestone, light gray, massive, wavy-bedded, thick-bedded ..2120. Limestone, bituminous, dark gray, massive, weatherswhite. . 2319. Limestone, argillaceous, yellowish, soft.4.... . . . . . . . . . . . . . . . 418. Limestone, argillaceous, light gray, shaly nodular, fossiliferous (E. mermeti), weathersyel-

lowish gray, with a few interbeds of massive, light gray limestone.10517. Limestone, gray, massive 916. Limestone, argillaceous, nodular . . . . . . . . . . . . .. . . . . . . . . . . . 2115. Limestone, argillaceous, yellowish brown, shaly, nodular, soft, with interbeds of massive,

thick-bedded, fossiliferous, bluish gray, bituminous limestone. 7414. Marl, yellowish, soft, nodular, shaly, with thick interbeds of massive, dark gray, strongly

bituminous limestone.1213. Limestone, argillaceous, dark gray, nodular, weathers white.3312. Marl, brownish to purplish gray, soft, fossiliferous, with a few interbeds of nodular, fossili-

ferous, argillaceous limestone . . . . . . . . . . . . . . . . . . . . . . . . . 3111. Limestone, argillaceous, bituminous, bluish gray, nodular, with interbeds of brownish and

purplish, bituminous shale . . . . . . . . . . . . . . . . . . . . . . . . . . . 3910. Limestone, strongly bituminous, dark bluish gray to black, nodular, thick-bedded . . . 169. Shale, calcareous, bituminous, silty, dark gray, laminated, becomes more calcareous up-

ward 40TOTAL, PULLUICANA GROUP: 1057 METERS

PARIATAMBO FORMATION8. Marl and argillaceous limestone, strongly bituminous, dark gray to black, laminated, with

a few interbeds of brownish gray, calcareous and bituminous quartz-siltstone.204TOTAL, PARIATAMBO FORMATION: 204 METERS

CHULEC FORMATION

7. Covered 536. Marl, gray, thin-bedded, weathers whitish gray, has a few massive interbeds of brownish

graylimestone. 210TOTAL, CHULEC FORMATION: 263 METERS

INCA FORMATION

5. Limestone, ferruginous, dark bluish gray, thin-bedded, with interbeds of ferruginous quartz-siltstone.75

4. Limestone, dark bluish gray, thick-bedded, massive, fossiliferous (Exogyra sp.), weatherslight rusty brown.15

3. Quartz-siltstone and quartz-sandstone, highly ferruginous, arkosic, calcareous, iron-stained,reddish to yellowish brown, fossiliferous (Exogyra sp., Trigonia sp.).45

2. Limestone, dark bluish gray, massive, compact, karstic, medium- to thick-bedded, weatherslight rustybrown.4

1. Quartz-sandstone, calcareous, ferruginous, reddish brown, thin-bedded.22TOTAL, INCA FORMATION: 161 METERS

1956 423


SECTION 11. SUNCHUBAMBASection measured along the San Jorge River, from Cerro Colmillo to 2 kilometers southwestof Hacienda Sunchubamba.

CHULEc FORMATION METERS52. Marl, thin-bedded, gray, fossiliferous (Knemiceras attenuatum, Enaloaster peruanus, Holec-

typus planatus, Bothriopygus sp.) weathers whitish gray, has a few interbeds of brownishgray limestone.60+

TOTAL, CHULEC FORMATION: 60+ METERS

INCA FORMATION51. Limestone, arenaceous, bluish gray, massive, thick-bedded, fossiliferous (Exogyra minos),weathers light brown.2050. Shale, dark gray to black, laminated, soft, fossiliferous (Knemiiceras ollonense, Desmoceras

chimuense, Paraizoplites nicholsoni, 1. inti, P. quilla, Yaadia hondaana, Pterotrigoniatocaimaana, Buchotrigonia abrupta), weathers brownish gray, has thin interbeds of darkgray limestone.57

49. Limestone, bluish gray, massive, thick-bedded. 448. Shale, black, laminated, soft, weathers yellowish brown to yellowish limestone.30

GOYLLARISQUISGA FORMATION47. Shale, quartz-siltstone and quartz-sandstone, medium-bedded, gray to greenish . . . . 1346. Quartz-sandstone, white to gray, cross-bedded, thick-bedded . . . . . . . . . . . . . 4845. Shale, poorly exposed.4544. Quartz-sandstone, white, medium-bedded.1843. Shale, dark gray to black, micaceous, laminated, contains plant remains and fresh-water

gastropods.3742. Quartz-sandstone, white to yellowish, coarse-grained to pebbly, medium- to thick-bedded,weathers yellowish brown, contains occasional coal fragments.. . . . . . . . . . 21141. Shale, black, silty, with fine interbeds of white quartz-siltstone . . . . . . . . . . . . 1040. Quartz-sandstone, white to yellow, compact, medium-bedded. . . . . . . . . . . . . 3039. Shale, black,laminated. 238. Quartz-sandstone, white to yellow, massive, medium-bedded . . . . . . . . . . . . . 3637. Shale and quartz-sandstone, finelybedded.. 1036. Quartz-sandstone, white, coarse-grained, cross-bedded, thick-bedded. 9TOTAL, GOYLLARISQUISGA FORMATION: 469 METERS

CARHUAZFORMATION35. Shale, bluish gray, soft, carbonaceous, with a few interbeds of quartz-sandstone.1034. Quartz-sandstone, medium-bedded, with shale intercalations . . . . . . . . . . . . . 1233. Shale, dark green to brownish yellow, soft, with a few interbeds of white quartz-sandstone. 3932. Quartz-sandstone, gray, medium-bedded. 431. Shale and quartz-sandstone, thin-bedded, with a few interbeds of subanthracite . . . 830. Quartz-sandstone, gray, medium-bedded. 929. Shale, varicolored, laminated, soft, with thin interbeds of quartz-siltstone.2428. Quartz-sandstone, greenish,medium-bedded.9

27. Shale, yellowish and pale purple, with a few interbeds of quartz-sandstone .5426. Quartz-sandstone, white to greenish, medium-grained, lenticular, cross-bedded . 6425. Shale, bluish to greenish gray, soft, with a few interbeds of quartz-sandstone . . . 8824. Quartz-siltstone and shale,thin-bedded. 523. Shale, carbonaceous, black, with thin interbeds of white quartz-sandstone, includes2-meter thick bed of plant-bearing, impureanthracite.23

22. Quartz-sandstone, gray to white, medium-grained, massive, cross-bedded, medium-bedded. 2021. Shale, bluish gray to black, contains poorly preserved plant remains.1020. Quartz-sandstone, white to greenish white, cross-bedded, massive, medium-bedded . . . 1519. Shale, poorly exposed. 4018. Quartz-sandstone, white, medium-grained, massive, medium-bedded, cross-bedded, withthin interbeds of carbonaceousshale.. 15

VOL. 108424


METERS17. Shale and quartz-sandstone, carbonaceous in the upper part.2016. Quartz-sandstone, white, massive, cross-bedded, channeled, with interbeds of dark gray

shalev.3515. Shale, varicolored, soft, with a few interbeds of quartz-sandstone.15814. Shale, varicolored, soft, with interbeds of cross-bedded, greenish gray, calcareous quartz-

sandstone.12013. Quartz-siltstone and shale, thin-bedded. 9

TOTAL, CAR1UAz FORMATION: 791 METERSUNCONFORMITYSANTA FORMATION12. Limestone, brownish, with interbeds of shale; at the top is an intraformational conglomerate

of lath-shaped limestone cobbles. 1911. Quartz-sandstone, calcareous, fine-grained. 1010. Limestone, brown to black, otlitic, massive, weathers yellowish brown ..459. Shale, iron black to dark gray, splintery, fossiliferous (Buchotrigoniac gerthii, Cyrena hktara-

zensis), with thin interbeds of nodular, brown limestone and of white quartz-sandstone. 858. Shale, quartz-siltstone, and quartz-sandstone, finely interbedded, ferruginous . . . . . 40

TOTAL, SANTA FORMATION: 199 METERS

CHIME SANDSTONE7. Quartz-sandstone, white to gray, hard, massive, fine- to medium-grained, very thick-

bedded, strongly cross-bedded, ridge-forming, weathers pale reddish.2316. Shale and quartz-siltstone, carbonaceous, micaceous, black, thin-bedded.155. Quartz-sandstone, gray to white, medium- to fine-grained, hard, thick-bedded, stronglycross-bedded. 262

4. Shale and quartz-siltstone, carbonaceous, black, thin-bedded . . ... . . . . . 53. Quartz-sandstone, white to gray, micaceous, thick-bedded, cross-bedded, weathers yellow-

ish brown..452. Quartz-siltstone and shale, carbonaceous, thin-bedded, coatains badly preserved plant re-

mains.461. Quartz-sandstone, white, fine-grained, medium-bedded, weathers reddish brown . . . 3+

TOTAL, CHIM7 SANDSTONE: 607+ METERSINTRUSIVE CONTACTDIORITE STOCK

SECTION 12. BANOS DE CHIMfYSection measured along the south side of the Chicama River, beginning 250 meters down-

stream from Bafos de Chimu', hot springs and settlement on the Trujillo to Sayapullo road,to 400 meters upstream from the same place.SANTA FORMATION METERS

17. Shale, black, splintery, with thin interbeds of dark brown, fossiliferous (Paraglauconia sp.)limnestone-.100±

CrnIMd SANDSTONE16. Siltstone, tuffaceous, light greenish gray, massive, thick-bedded, weathers reddish brown . 3615. Quartz-sandstone, dark gray, thin-bedded, weathers reddish, has interbeds of shale - . 1314. Quartz-sandstone, medium to dark gray, massive, strongly cross-bedded, lenticular, me-

dium- to thick-bedded, weathers reddish brown..5613. Quartz-sandstone, dark gray, thin-bedded, with iaterbeds of shale.1612. Quartz-sandstone, white, medium- to fine-grained, hard, cross-bedded, massive, very thick-

bedded, weathers light reddish brown to light gray.13611. Quartz-sandstone, white to medium gray, medium to fine-grained, cross-bedded, lenticular,

medium- to thick-bedded, weathers brownish red, with a few interbeds of shale. . . . 10410. Quartz-sandstone, white to light gray, hard, medium- to fine-grained, cross-bedded, very

19S6 425


METERSthick-bedded, weathers light gray . . . . . . . . . . . . . . . . . . . . . . . 80

9. Shale, carbonaceous, with plantremains.18. Anthracite.17. Shale, carbonaceous, black, bears plant remains . . . . . . . . . . . . . . . . . . 26. Quartz-sandstone, light gray, cross-bedded. 25. Shale, carbonaceous, black, laminated, bears plant remains . . . . . . . . . . . . . 24. Quartz-sandstone, dark gray, medium- to fine-grained, cross-bedded, lenticular, medium-

bedded ...... . . .. . . .......I.I.I. ....... 153. Quartz-sandstone, dark gray, laminated, micaceous, with a few interbeds of shale . . . 72. Quartz-sandstone, white to yellowish brown, medium- to fine-grained, hard, cross-bedded,

lenticular, weathers reddish brown.391. Quartz-sandstone and quartz-siltstone, dark gray, thin-bedded, cross-bedded, bears plantremains, weathers reddish brown.132

TOTAL, CHIMU' SANDSTONE: 642 METERS

JURASSIC"CHICAMA BEDS"

Shale dark gray to black, tuffaceous, soft, laminated, weathers purplish gray to reddishpurple.

SECTION 13. CALLACUYANSection measured at the Callacuyan coal mine, 7 kilometers northeast of Quiruvilca, De-

partment of La Libertad.CARHUAZ FORMATION METERS21. Shale and quartz-siltstone, medium-bedded.6920. Quartz-sandstone, white, cross-bedded, ridge-forming, medium-bedded.8119. Shale and quartz-siltstone, reddish and purplish, thin-bedded.27918. Quartz-sandstone, arkosic, white, cross-bedded, medium-bedded.1517. Shale and quartz-siltstone, brownish and purplish, thin-bedded, with thin interbeds of

quartz-sandstone.. 8616. Quartz-sandstone, brownish gray, medium-grained, massive, thick-bedded.1015. Shale, reddish and brownish gray, laminated.3414. Quartz-siltstone, slightly ferruginous, dirty gray, medium-bedded, weathers greenish andreddish, has a few interbeds of shale.16213. Shale, dark gray, laminated, interbedded with cross-bedded, medium-grained, whitequartz-sandstone. 215TOTAL, CARHUAZFORMATION: 805 METERS

SANTA FORMATION12. Limestone, argillaceous, brown, thin-bedded, with thin interbeds of fossiliferous (Para-

glauconia sp.), black shale.. . . . . . . . . . . . . . . . . . .

I

. 3511. Limestone, arenaceous, dark brown, thin-bedded, with interbeds of quartz-sandstone . 6110. Shale, black, splintery, thin-bedded, interbedded with fossiliferous (Buchotrigonia gerthii,Cyrena huarasensis), brown limestone.1269. Shale, black, thin-bedded, with interbeds of quartz-siltstone.57TOTAL, SANTA FORMATION:279 METERS

CHICM6 SANDSTONE8. Quartz-sandstone, white to cream, cross-bedded, very thick-bedded, ridge-forming, weath-

ers reddishbrown. 637. Quartz-sandstone, white, hard, verythick-bedded, cross-bedded, with interbeds of thin-

bedded, carbonaceous, dark shale.1496. Anthracite irnterbedded with carbonaceous shale and quartz-siltstone. 7

S. Quartz-andstone, white to gray, lenticular, with interbedsof carbonaceous shale ..

424. Shale, carbonaceous, black, with interbeds of anthracite ..20

VOL. 108426


METERS3. Quartz-sandstone, white to gray, cross-bedded, massive, hard, thick-bedded ... ..- . 812. Anthracite........................ .2......... .

1. Quartz-sandstone, white, fine-grained, hard, massive, thick-bedded.87TOTAL, CHIME SANDSTONE: 451+ METERS

SECTION 14. SANTO CRISTO BRIDGE

Section measured along the Maraf6n River, from 200 meters upstream of the Santo CristoBridge, just south of Quiches, to 300 meters downstream from this bridge.

ROSA FORMATION METERS

5. Quartz-siltstone and shale, slightly calcareous, deep cherry-red, with interbeds of gypsumin the lower part.135+

TOTAL, ROSA FORMATION: 135+ METERS

UNCONFORMITYCRISNEJAS FORMATION

4. Limestone, dolomitic, medium gray to greenish, massive, thick-bedded, weathers brownishgray, with interbeds of quartz-siltstone and shale... . . . . . . . . . . . . 90

3. Shale, calcareous, light green,laminated. 272. Limestone, light brownish gray, massive, thick-bedded, fossiliferous (Oxytropidoceras

douglksi), with interbeds of nodular marl . . . . . . . . .-. . 1261. Shale, calcareous, dark bluish gray, splintery, with interbeds of nodular, fossiliferous

(Knemiceras sp., Trigonia sp., Liopistha sp., Ostrea sp.) light greenish and bluish marl . 270+TOTAL, CRISNEJAS FORMATION: 613+ METERS

SECTION 15. SIHUAS

Composite section; the lower Goyllarisquisga formation was measured along the south sideof Quebrada Colpa, just west of Sihuas; the overlying beds were estimated in the lower partof the Pasacancha River, southwest of Sihuas.

PARIATAMBO FORMATION METERS

9. Limestone and marl, strongly bituminous, black, fossiliferous (Oxytropidoceras sp., Lyelli-ceras sp.), weathers dark brownish gray . . . . . . . . . . . . . . . . . . . . . 200+

TOTAL, PARIATAMBO FORMATION: 200+ METERS

CHULEC FORMATION8. Marl, light greenish gray, very fossiliferous (Knemiceras raimondii, K. raimondii tardum, K.

attenuatum, Prolyelliceras peruvianum, Douvilleiceras monile), with interbeds of shale andof massive, greenish limestone .... . . . . . . . . . . . . . . . . . . . . . 250


GOYLLARISQUISGA FORMATION7. Quartz-sandstone, light gray, medium-bedded, strongly cross-bedded, with a few interbeds

of greenish gray calcareous quartz-siltstone.. . . . . . . . . . . . . 87.. . . .86. Shale and quartz-siltstone, greenish.. . . . . . . . . . . . . . . . . . . . . . .1205. Quartz-sandstone, white, medium-bedded, weathers reddish brown, has thin interbeds of

black shale.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. Shale, poorly exposed.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373. Quartz-sandstone, white to light gray, speckled, cross-bedded, weathers light reddish

brown . ....... . . .. . . .. . . . ....................-........ 1572. Quartz-siltstone, dark greenish gray, with interbeds of purple and greenish shale . . - . 631 . Quartz-siltstone, greenish and brownish, medium-bedded, weathers reddish brown, has a few

interbeds of splintery, greenish and purplish shale . . . . . . . . . . . . . . . . 15+TOTAL, GOYLLARISQUISGA FORMATION: 516+ METERS

1956 427


SECTION 16. SANTA CLARAComposite section; the Cajamarca formation was estimated just east of Hacienda Santa

Clara; the Celendin formation was measured along the south side of the Rupac (Sihuas) Riverat San Pedro; and the Chota formation was estimated at Ahijadero, just west of Santa Clara.CHOTA FORMATION METERS

7. Shale, dark red, soft, splintery, with interbeds of dark red quartz-siltstone.900+6. Quartz-siltstone, calcareous, greenish gray . . . . . . . . . . . . . . . . . . . . . 20

TOTAL, CHOTA FoRMATION: 920+ METERS

CELENDfN FORMATION5. Marl, light gray, fossiliferous (Hemiasterfourneli, Goniopygus hemicidariformis, Goniopygus

superbus), splintery, nodular, with interbeds of tan limestone . . . . . . . 3174. Limestone, argillaceous, dark gray, nodular, with interbeds of whitish marl . . . . . 483. Marl and shale, greenish yellow, very fossiliferous (Texanites sp., Lenticeras lissoni, Tissotiahalli, Ostrea nicaisei) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1632. Marl, white, nodular, thick-bedded, with interbeds of dark gray nodular limestone . 30

TOTAL, CELENDfN FORMATION: 558 METERS

CAJAMARCA FORMATION1. Limestone, dark bluish gray, hard, lithographic, thick-bedded, scarp-forming, with a few

interbeds of bluish gray nodular marl . . . . . ..

. . . . . . . . . . . . . . 800TOTAL, CAJAMARCA FORMATION: 800 METERS

SECTION 17. CARHUAZSection (fig. 20) measured on Cerro Huallhua, on the western side of the Santa River, 4

kilometers northwest of Carhuaz. It contains the type sections of the Santa and Carhuazformations.PARIAHUANCA FORMATION METERS23. Limestone, slightly bituminous, medium-gray, thick-bedded, fossiliferous, weathers light

gray, forms a scarp.45TOTAL, PARIAHUANCA FORMATION: 45+ METERSCARHUAZ FORMATION22. Quartz-sandstone, light greenish, thin to medium-bedded, lenticular, weathers dark green-

ish, has interbeds of shale and yellowish limestone which become abundant upward 15021. Shale, slightly calcareous, dark green to brown, thin-bedded, soft, with interbeds of massive,

greenish to brownish, calcareous quartz-siltstone.. . . . . . . . . . . . . . 177

20. Shale, dark greenish gray, laminated, soft, with interbeds of dark green tuff and darkbrownish gray limestone ..32919. Shale, dark greenish, laminated, soft, with thin interbeds of quartz-siltstone. . . . . . 107

18. Shale, slightly calcareous, brownish yellow to greenish, with interbeds of medium-bedded,dark brownish, slightly calcareous quartz-sandstone . . . . . . . . . . . . . . . 96

17. Limestone, dark brownish yellow, fossiliferous (Ostrea sp.), weathers dark brown . . 116. Quartz-sandstone, slightly calcareous, greenish and brownish, with interbeds of light brown,

silty shale and a few thin beds of fossiliferous, dark limestone . . . . . . . . . . . 8615. Shale, silty, greenish to brownish, withinterbeds of quartz-sandstone ..13014. Shale, calcareous, silty, light brown to light purple, with interbeds of brownish, calcareous

quartz-sandstone and thin, fossiliferous, brownish limestone . . . . . . . . . . .. 7013. Quartz-sandstone, greenish gray to brownish, medium-grained, medium-bedded, lenticular,cross-bedded, weathers rusty brown, has interbeds of purple, calcareous shale . . 42

12. Shale, brownish to purple, laminated, soft, with thin interbeds of white quartz-sandstone 5711. Quartz-sandstone, white to light gray, medium- to fine-grained, cross-bedded, medium-

bedded, weathers rusty brown, forms a scarp. . . . . . . . . . . . . . . . . 116

428 VOL. 108


METERS10. Shale, dark greenish and brownish, laminated, with interbeds of brownish quartz-sand-

stone9. Gypsum ...................................

8.Shale.7. Gypsum6. Shale, dark gray, laminated, soft, with interbeds of dark brown, platy, fossiliferous (Val-

anginites broggii, Buckotrigonia gerthii) limestone and of brownish quartz-siltstone.TOTAL, CARHUAZ FORMATION: 1554 METERS

SANTA FORMATION5. Limestone, dark gray, massive, thick-bedded, platy, ledge-forming, weathers medium-gray.4. Limestone, dark gray, slightly argillaceous, platy, medium-bedded . . . . .. .. .3. Limestone, dark gray, somewhat dolomitic, medium-bedded, platy, fossiliferous (Cyrena

huarasensis, Paragkauconia strombiformis), with large limestone concretions and chertnodules, weathers yellowish brown, has interbeds of splintery, grayish black shale -

2. Shale, calcareous, varicolored, laminated, soft, splintery . . . . . .. .. . .....

TOTAL, SANTA FORMATION: 341 METERS

CHIMU' SANDSTONE1. Quartz-sandstone, white to reddish, hard, thick-bedded, scarp-forming, weathers reddishbrown.

TOTAL, CHIME SANDSTONE: 80+ METERS

53252

131

15110

2556

80+

Oxyfropidoceras carbonariwn zone 2.ALBIAN Krnemiceras ralmondfizons-

Parahoplites nicholsoni zone

APTIAN

BARREMIAN-~~ ~ ~ ~ ~ ~ =-2-

HAUTERIVIAN

Valanginites broggiil zone

VALANGINIAN

PARATAMBO FI (98+m)CHULEG FM. (32Mn)

PARIAHUANCA FM.(95m.)

GARHUAZ FM.(1554 m.)

SANTA FM(341m.)

GHIMU FM (100 4rn.)

FIG. 20. Callej6n de Huaylas stratigraphic section. Composite of theCarhuaz and Pariahuanca sections.

1956 429


SECTION 18. PARIAHUANCASection measured along the north side of the Pariahuanca River, just north of Pariahuanca,

between Huaraz and Carhuaz.PARIATAMBO FORMATION METERS14. Limestone, bituminous, dark gray, fossiliferous, interbedded with shaly, bituminous marl

which contains abundant spherical concretions of fossiliferous (Oxytropidoceras carbo-narium, Lyefliceras ulrichi, L. lyelli, Brancoceras aegoceratoides, Tnocera'mus sp.) lime-stone... ............ . . .. . . .. . .. . . . .. . . 98+

TOTAL, PARIATAMBO FORMATION: 98+ METERS

CHULEC FORMATION13. Shale, calcareous, brownish black, splintery.. . . . . . . . . . . . . . . . . .512. Marl, whitish gray, nodular, very fossiliferous (Douvilleiceras monile, Protanisoceras

biancheti, Exogyra minos), with a few interbeds of massive, dark gray, brownish-weather-ing limestone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27


PARIAHUANCA FORMATION11. Limestone, slightly bituminous, medium gray, massive, thick-bedded, fossiliferous (Para-

hoplites sp., rudistid fragments, miliolid Foraminifera), weathers light gray.6010. Limestone, arenaceous, massive, thick-bedded, weathers dark gray to bluish gray . . 159. Limestone, slightly argillaceous, dark brown, medium- to thick-bedded, massive, weathers

light brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20TOTAL, PARIAHUANCA FORMATION: 95 METERSCARHUAZ FORMATION

8. Quartz-siltstone and quartz-sandstone, calcareous, white to gray, thin- to medium-bedded,with a few interbeds of shale . . . . . . . . . . . . . . . . . . . . . . . . . 51

7. Shale, tuffaceous, slightly calcareous, purple . . . . . . . . . . . . . . . . . . . . 56. Quartz-sandstone, light gray, fine-grained, thin-bedded, with thin interbeds of carbonaceous

shale.. ................................. . 545. Shale and quartz-sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . 754. Shale, tuffaceous, calcareous, purple and green, splintery, with interbeds of dark purple,

tuffaceous siltstone and of fossiliferous (Paraglauconia sp., Cyrena huarazensis) lime-stone.91

3. Shale, light gray and light greenish gray, splintery, with a few interbeds of brownish lime-stone.69

2. Limestone, medium gray, thin-bedded, weathers brownish, has interbeds of shale . . . . 151. Shale, slightly calcareous, brownish to greenish gray, splintery, with thin interbeds of

brownish quartz-siltstone ..... . . . . . . . . . . . . . . . . . . ... . 272+TOTAL, CARHUAZ FORMATION: 632+ METERS

SECTION 19. UCHUPATASection measured along the trail from Uchupata to Rio Maraft6n, on the north side of the

Pushca River, from La Merced to 4 kilometers northeast of Hacienda Uchupata.CHOTA FORMATION METERS11. Shale, calcareous, deep red, gypsiferous, with a few interbeds of green shale .120+10. Shale, calcareous, grayish green, with a few interbeds of siltstone . . . . . . . . . . . 60

TOTAL, CHOTA FORMATION: 180+ METERS

CELENDfN FORMATION9. Marl, light gray, nodular, soft, weathers white.. . . . s8. Shale, calcareous, slightly silty, yellowish, with a few interbeds of dark brown limestone . 40

430 VOL. 108


M

7. Marl, light gray, nodular, weathers white, has a few interbeds of limestone.6. Marl, light gray, hodular, soft, weathers white...... .... ... ... . . .

5. Marl, light gray to tan, nodular, with few interbeds of massive, light gray limestoneTOTAL, CELEND&N FORMATION: 163 METERS

JUMASHA FORMATION4. Limestone, light gray, very thick-bedded, weathers dark bluish gray, with a few interbeds

of white to greenish marl. From the lowest beds, Lyelliceras ulrichi and Oxytropidocerasdouglasi were collected ............................

TOTAL, JUMASHA FORMATION: 750 METERS

CRISNEJAS FoRMATIoN3. Marl, light gray, nodular, fossiliferous (Lyelliceras ulrichi, Knemiceras ovale), with inter-

beds of brownish graylimestone.2. Marl and arenaceous limestone, light gray, fossiliferous (Parengonoceras pernodosum,

Knemiceras syriacum, K. ziczag) . .......................TOTAL, CRISNEJAS FORMATION: 190 METERS

GOYLLARISQUISGA FORMATION1. Quartz-sandstone, white, coarse-grained to pebbly, soft, cross-bedded, with interbeds of

quartz-pebbleconglomerate.TOTAL, GOYLLARISQUISGA FORMATION: 413+ METERS

SECTION 20. HACIENDA PALCASSection measured along the south side of the Pushca River, at Hacienda Palcas.

JUMASHA FORMATION I

19. Limestone, medium gray, thick-bedded, weathers dark dove gray, bears Foraminifera18. Limestone,argillaceous.17. Limestone, medium gray, massive, thick-bedded, weathers dark brownish .

16. Dolomite, thin-bedded, brown........................15. Dolomite, light gray to light orange-brown, massivle, thick-bedded, karstic, weathers dark

orange-brown14. Dolomite, silty, medium gray, somewhat nodular.. . . . . ...... .... . .

TOTAL, JUMASHA FORMATION: 820 METERS

PARIATAMBO FORMATION13. Shale, calcareous, dark bluish gray, splintery, soft . . . . . . . . . . . . .

12. Limestone, strongly bituminous, dark gray to black, medium-bedded, platy, weathersmedium gray y...............................

11. Shale, calcareous, bituminous, fossiliferous (Oxytropidocerassp.).10. Limestone, strongly bituminous, dark brownish to dark purplish gray, medium- to thick-

bedded, platy, fossiliferous (Oxytropidoceras sp., Inoceramus sp.), with a few interbeds ofbituminousmarl.

9. Shale, calcareous, bituminous, medium-bedded ...................8. Limestone, bituminous, black, thick-bedded, fossiliferous (Oxytropidoceras sp., Lyelliceras

sp.), weathers dark brownish gray .. .....................TOTAL, PARIATAMBO FORMATION: 153 METERS

CHULEC FORMATION7. Marl, whitish green to whitish blue, shaly, soft, poorly fossiliferous, with a few interbeds

of medium gray, nodular limestone . . . . . . . . . . . . . . . . .

6. Limestone, argillaceous, medium gray, fossiliferous (Enallaster sp., Holectypus sp., Bothrs-opygus sp., Pseudodiadema sp.), thick-bedded, with a few interbeds of quartz-siltstone .


[ETERS123868

750

141

50

413+

rETERS39029288

28560

15

84

7912

35

80

22

1956 431

0


GOYLLARISQUISGA FORMATION METERS5. Quartz-siltstone and shale, brownish to greenish, thin-bedded . . . . . . . . . . . . 214. Quartz-sandstone and quartz-siltstone, brown to greenish, medium- to thick-bedded,

weathers dark greenish . . . . . . . . . . . . . . . . . . . . . . . ... . . 753. Quartz-sandstone, white, soft, cross-bedded, medium- to thick-bedded . . . . . . . . 212. Shale and quartz-siltstone, varicolored, thin-bedded . . . . . . . . . . . . . . . . 101. Quartz-sandstone, calcareous, white, coarse-grained to pebbly, cross-bedded, soft, weathers

light reddish to white . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24+TOTAL, GOYLLARISQUSGA FORMATION: 151+ METERS

SECTION 21. POMACHACA

Section measured along the north side of the Pushca River, from 1 kilometer downstreamfrom Pomachaca, 10 kilometers southwest from Hauri, to Pomachaca.JUMASHA FORMATION METERS28. Limestone, dark gray, massive, thick-bedded, dolomitic, scarp-forming, weathers dark

dove gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300+TOTAL, JUMASHA FORMATION: 300+ METERSPARIATAMBO FORMATION27. Limestone, bituminous, black, medium-bedded, platy, weathers brownish gray.6026. Marl and limestone, bituminous, black, thin-bedded, platy, fossiliferous (Oxytropidoceras

peruvianum, Venezoliceras venezolanum, LyelUiceras lyelli), weathers brownish black . . 45ToTAL, PARIATAMBO FORMATION: 105 METERS

CHULEC FORMATION25. Shale, dark gray, fossiliferous, with interbeds of nodular, brownish gray marl. 1824. Quartz-siltstone, calcareous, white to light brown, fossiliferous (Knemiceras sp.), medium-

bedded ...... . . . . . . . . . . . . . . . . . . . . ... . . . . . . . 423. Marl, light gray, nodular, very fossiliferous (Douvilteiceras monile, Knemiceras attenuatum,

K. raimondii) weathers light brownish gray to light bluish gray. . . . . . . . . . . 722. Marl, slightly silty, light gray, nodular, soft, fossiliferous (Knemiceras raimondii, Branco-

ceras aegoceratoides, Enalkaster perua-nus, Holectypus planatus, Bothriopygus sp., Exogyramsinos), weathers light brownish gray, has interbeds of massive, thick-bedded, dark gray,argillaceous limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

21. Marl, dark gray, nodular, fossiliferous (Knemsceras sp.) . . . . . . . . . . . . . . . 2120. Limestone, dark gray, nodular, friable, fossiliferous . . . . . . . . . . . . . . . . . 319. Quartz-siltstone, argillaceous, slightly calcareous, light grayish green, laminated, fossilifer-

ous. 1018. Marl, dark gray, nodular, fossiliferous (Knemiceras sp., Beaudenticeras sp., Exogyra minos),

weathers bluishgray. 617. Marl, dark gray, nodular, very fossiliferous (Parahoplites sp., Enallaster peruanus, Bothrio-

pygus sp., Exogyra minos), with a few interbeds of white, argillaceous quartz-siltstone . 5TOTAL, CHULEC FORMATION: 90 METERS

CARHUAZ FORMATION16. Quartz-sandstone, calcareous, white to brown, thin- to medium-bedded, with a few inter-

beds of shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3414. Shale, light bluish gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2113. Quartz-sandstone, white to light brown, medium- to thick-bedded, cross-bedded, speckled,

with interbeds of carbonaceous shale . . . . . . . . . . . . . . . . . . . . . . 17712. Shale, poorlyexposed.. . . . . . . . . . . . . . . . . . . . . . . . . . . 10511. Quartz-sandstone, white to light brown, medium- to fine-grained, cross-bedded, medium- to

thin-bedded, with interbeds of carbonaceous shale . . . . . . . . . . . . . . . . 17410. Shale, dark gray, laminated, with interbeds of fine-grained quartz-siltstone. . . . . . . 399. Quartz-sandstone, white to light brownish, cross-bedded, medium- to thick-bedded . . . 54

432 VOL. 108

1956 BENAVIDES: CRETACEOUS SYSTEM IN PERU 433

METERS8. Shale, black, laminated, soft, with interbeds of white to light brown, medium-bedded, fine-

grained quartz-sandstone.897. Shale, greenish and purple-red, with interbeds of quartz-siltstone.166. Shale, greenish, bluish, and brownish, soft, with thin interbeds of silty limestone . . . 395. Quartz-sandstone, white, medium-bedded, weathers brownish.8

TOTAL, CAREUAZ FORMATION: 756 METERSUNCONFORMTYSANTA FORMATION

4. Limestone, black, massive, medium- to thin-bedded, platy, fossiliferous (Paraglauconiasp.).58

3. Shale and quartz-sandstone, thin- to medium-bedded.25TOTAL, SANTA FORMATION: 83 METERS

CiarM6 SANDSTONE2. Quartz-sandstone, white, fine- to medium-graiaed, hard, massive, very thick-bedded, cross.

bedded, scarp-forming, weathers light reddishbrown. 3971. Quartz-sandstone, white, very thick-bedded, massive, weathers light yellowish or reddish

brown, has a few interbeds of carbonaceous shale.. . . . . 236+TOTAL, CHIM'7 SANDSTONE: 633+ METERS

PALEONTOLOGYGENERAL STATEMENT

BECAUSE OF THE IMPORTANCE of ammonitesin the stratigraphy of the Cretaceous, bothduring the field work and in the laboratory,attention has been focused on this group.Seventy species of ammonites, ranging fromthe Valanginian to the Santonian, are de-scribed; 24 species are considered to be new.

This succession of ammonites is character-ized by the preponderance of the so-called"pseudoceratites." Phylloceratid species arewanting, and the lytoceratids are representedby only a few strongly ornamented hamitidswhich some authors would classify within theAmmonitina, sensu stricto.The Peruvian faunas belong to a faunal

province which includes Colombia, Vene-zuela, and Brazil. The faunas of this realmare closely comparable and parallel with thoseof Mexico, the Gulf Coast, southern Europe,northern Africa, Madagascar, the MiddleEast, India, and Borneo. The analogy withthe Tunisian faunas, especially when the lateCenomanian and the early Turonian are con-cerned, is particularly striking. Some species,e.g., Douvileiceras monike, Lyelliceras lyelli,Desmophyllites gaudama, etc., have been re-ported throughout this domrain. Except forthe genus Buchiceras, sensu stricto, none ofthe 34 studied genera is limited to SouthAmerica, and almost every species is closelycomparable to if not conspecific with Mediter-ranean species.Ammonites are particularly abundant in

the transgressive marls and limestones of theInca and Chulec formations, in the black,strongly petroliferous, platy limestones andmarls of the Pariatambo formation, and inthe near-shore, shallow-water shales andmarls of the Cofior, Romir6n, and Celendin

formations. The Yumagual formation, al-though containing beds packed with exo-gyroids, has yielded only a few specimensbelonging to three species of ammonites. Theoverlying Mujarrdn formation, also rich inexogyroids, has not produced a single am-monite specimen.The descriptions of many of the species can

be found only in well-equipped libraries, forsome of them are in rare European publica-tions, and others are in obscure and ephem-eral South American journals. The presentwriter, having available the facilities of theexcellent library of the American Museum ofNatural History, has decided, therefore, toinclude complete descriptions of all the stud-ied species.

In the descriptions, the standard measure-ments and terminology are used. The follow-ing terms have been used to refer to theumbilicus:Extremely widely umbilicated (66% of the diame-

ter)Widely umbilicated (50 to 66% of the diameter)Fairly widely umbilicated (34 to 50% of the

diameter)Fairly narrowly umbilicated (17 to 34% of the

diameter)Narrowly umbilicated (8 to 17% of the diameter)Very narrowly umbilicated (umbilicus nearly

closed)The standard measurements-diameter

(D), whorl height (H), whorl thickness (T),and diameter of the umbilicus (U)-weretaken at the largest possible diameter, andthey are expressed in millimeters. The lastthree measurements (H, T, and U) are alsogiven in terms of percentage of the diameter(D/H, D/T, and D/U).

434


SYSTEMATIC PALEONTOLOGY

PHYLUM MOLLUSCASUBPHYLUM CEPHALOPODA

CLASS NAUTILOIDEAORDER NAUTILIDA SPATH

FAMILY PARACENOCERATIDAE SPATH, 1927LISSONICERAS,1 NEW GENUS

DESCRIPTION: Lissoniceras includes thoseunusual nautiloids, such as Nautilus mermetiCoquand (1862, p. 166), selected as thegenotype, and Nautilus triangularis Montfort(d'Orbigny, 1840-1842, pl. 17), which have alenticular shape, triangular whorl section,and which, unlike the Aptian genus Hemi-nautilus, have the sides converging towards anarrow, fastigate venter. The external suturehas an angular and high ventral saddle, agently curved large. lateral lobe, a small,narrowly rounded saddle already about theumbilical shoulder, and a very small lobe.The siphuncle is extracentrodorsan.REMARKS: Lissoniceras resembles in shape

the Eocene genus Deltoidonautilus Spath, butdiffers in possessing a goniatitic suture witha rounded ventral saddle. The two speciesreferred to Lissoniceras are Cenomanian.Durham (1946, p. 428), reviewing the

literature on Cretaceous nautiloids of SouthAmerica, remarked: "Nautilus mu-nieri Chof-fat is described and figured by Schlagintweit(1912, pp. 99-100, text fig. 3, pl. 6, fig. 9)from the Pampa de la Culebra, Peru, in bedswhich he considered as of Cenomanian age.From the figures and description, this specieswould appear to belong to a genus closelyallied to Heminautilus, differing from Hemi-nautilus largely in the absence of a flattenedventer." Nautilus munieri Choffat is con-sidered by Pervinqui&re (1907, p. 46), and thepresent writer agrees with him, as a synonymof Nautilus mermeti Coquand, the genotypeof Lissoniceras.

LiOssoiceras mermeti (Coquand)Plate 40, figures 1-3

Nautilus Mermwti COQUAND, 1862, p. 166, p1.11, figs. 1-2.

X Lissoniceras is named for Dr. Carlos I. Liss6n, whohas contributed greatly to the knowledge of the Cre-taceous in Peru.

Nautilus Munieri CHOFFAT, 18S6, 1898, ser. 1,p. 1, pl. 1, fig. 2, pl. 2, fig. 1.

Nautilus Mermeti Coquand; PERVINQUIkRE,1907, p. 46.

Nautilus Munieri Choffat; SCHLAGINTWEIT,1912, p. 99, pl. 6, fig. 9.Seven specimens, the largest of which is 150

mm. in diameter, are available for study.DESCRIPTION: The conch is large, lenticu-

lar, flat, with the umbilicus almost closed.The whorl section is compressed, triangular,with indistinct umbilical wall and verybroadly rounded shoulder. The sides convergewith slight convexity towards the fastigate,narrowly rounded to angular venter. Thegreatest thickness, occurring at about themiddle of the inner third, is about one-halfof the whorl height. The septa are veryclosely spaced. The suture is strongly in-flexed forward; it has a very high and angularventral saddle, a large and broadly curvedlateral lobe, a small rounded saddle just abovethe umbilical shoulder, and a very small lobecentered at the umbilical seam (fig. 21).

t

FIG. 21. Lissoniceras merneti (Coquand).Suture line of specmen A.M.N.H. No. 27381/1 :1;Xi.

REMARKS: Lissoniceras mermeti resemblesL. triangulkris Montfort in general shape andsuture but differs because of its more com-pressed whorl section. In the latter, thegreatest whorl thickness is about four-fifthsof the whorl height.OCCURRENCE: Lissonsceras mermti is a

fairly common species in the upper Ceno-manian Romir6n formation, in bed 43 of thePolloc section (A.M.N.H. No. 27381) andin bed 44 of the Celendfn section (A.M.N.H.No. 27381/1). In both localities, it is asso-ciated with Neolobies kummeli, Forbesiceras

1956 435


sp. indet., Acanthoceras chasca, A. pollocense,and A. sangakense.

Schlagintweit reported one specimen fromPampa de la Culebra, near Cajamarca.

CLASS AMMONOIDEASUPERFAMILY HAMITACEA WRIGHT AND

WRIGHT, 1951FAMILY ANISOCERATIDAE HYATT, 1900

PROTANISOCERAS SPATE, 1923Protanisoceras blancheti (Pictet and Campiche)

Plate 40, figures 4-5Ancyloceras Blancheti PICTET AND CAMPICHE,

1861 (1858-1864), p. 33, pl. 47, figs. 1, 2a-d(lectotype), 3-10.

Ancyloceras Bkancheti Pictet et Camp.; SOM-MERMEER, 1910, p. 377.Two specimens are assigned to this species.DEscRimTiON: The conch is ancyloceratoid,

coiled in a single plane. The intercostal whorlsection is subcircular and slightly depressed;the costal whorl section is similar but flat-tened on the venter. There are about threeribs in a distance equivalent to the corre-sponding diameter; the ribs are single, high,very sharp, and have wider and roundedinterspaces. On the dorsum, the ribs are onlyfaintly indicated. At the ventrolateral shoul-ders they thicken and form a very faint,blunt tubercle. In the illustrated specimen(A.M.N.H. No. 27382) the ventrolateraltubercles disappear adorally. The suture linehas a trifid dorsal lobe and a broad firstlateral saddle.REMARKS: The Andean specimens of

Protanisoceras blancheti have fainter ventro-lateral tubercles than the European occur-rences illustrated by Pictet and Campiche,and they approach Hamites PraegibbosusSpath, from the mammillatum zone of theEnglish middle Albian, the ribs of which have"sometimes. . . a suggestion of differentia-tion on the venter but not actual tubercula-tion" (Spath, 1923-1943, vol. 2, p. 627).

Spath (1930, p. 58) has described a similarform, Protanisoceras sp., from the SamanaRange, India, where it is associated withDouvilkiceras mammillatism and other middleAlbian speces.OCCURRENCE: Protanisoceras blancheti was

collected from the Chulec formation, in bed67 of the Cajamarca section (A.M.N.H. No.

27382/1) and from the Crisnejas formation,in bed 9 of the Celendin section (A.M.N.H.No. 27382); in the latter locality, it is asso-ciated with several species of Knemiceras andParengonoceras. Sommermeier reports it fromPariahuanca.

In England, the genus Protanisoceras isconfined to the lowest Gault (mammillatumand dentatus zones) (Spath, 1930, p. 51).

FAMILY TURRILITIDAE MEEK, 1876PARATURRILITES BREISTROFFER, 1947Paraturrilites lewesiensis (Spath)

Plate 40, figures 8-9Turrilites Bergeri Brogniart; SHARPE, 1857

(1853-1857), p. 65, pl. 26, fig. 10 (only).Turrilites cf. Bergeri Brogniart; SCHLAGINTWEIT,

1912, p. 89.Turrilites lewesiensis SPATH, 1926, p. 429.Mariella lewesiensis (Spath); SPATH, 1923-

1943, vol. 2, p. 512.Paraturrilites lewesiensis (Spath); WRIGHT

AND WRIGHT, 1951, p. 17.Four specimens are referred to this British

species.DESCRIPTION: The conch is a narrowly um-

bilicated sinistral turricone with an apicalangle of about 30 degrees. The whorl sectionis polygonal; the lower shoulder, between theimpressed zone and the outer gently convexsurface, is angular; the upper or siphonalshoulder is rounded and smooth. There areabout 23 ribs per volution, which are veryconspicuous in the lower impressed zone buttend to vanish in the outer margin, wherethey are obliquely set. Each rib bears fourprominent rounded tubercles which form fourdistinct spiral rows. The lowest tubercle is atthe suture with the next volution; the lowertwo tubercles are more closely spaced thanthe upper ones. The uppermost tubercle isslightly elongated radially.REMARKS: Paraturrilites acostac (d'Or-

bigny, 1851, p. 380), from the ColombianCretaceous, differs because of the lack of ribs,the larger size of the tubercles, and the smallernumber of them per volution. Paraturrilitesbergeri (Brogniart) has less prominent tuber-culation and more distinct ribs than P. lew-esiensis. Furthermore, the tubercles areelongated instead of rounded as in the latterspecies.

VOL. 108436


OCCURRENCE: Three specimens (A.M.N.H.No. 27383) of Paraturrilites lewesiensis werecollected from the Yumagual formation, inbed 111 of the Cajamarca section, where it isassociated with Sharpeiceras occidentale. Afourth specimen (A.M.N.H. No. 27383/1)comes from the same formation, bed 27 of theLajas section.

Paraturrilites lewesiensis is found in theVariacns zone of the English Cenomanian(Wright and Wright, 1951, p. 17).

FAMiLY BACULITIDAE MEEE, 1876BACIULITES LAMARCK, 1799

Baculites sp. indet.A single, poorly preserved fragment

(A.M.N.H. No. 27384) is mentioned to recordthe presence of the genus. It has a length of25 mm., and the oval cross section has thediameters of 8 and 11 mm. The suture isbadly weathered.

Baculites sp. indet. was obtained from theCelendin formation in the Bambamarcasection.

FAMILY NOSTOCERATIDAE HYATT, 1894BOSTRYCHOCERAS HYATT, 1900

Bostrychoceras? sp. indet.Plate 40, figures 6-7

The only available specimen (A.M.N.H.No. 27385) is an entirely septate, completevolution of an apparently dextral turricone.The umbilicus is very large. The whorl sec-tion is subcircular; the whorls are in contact.The volution has 30 single, smooth, sharp,obliquely set ribs which are more conspicuouson the outside and almost entirely attenuatedon the umbilical wall.The material available makes even generic

determination difficult. Because of its orna-mentation Bostrychoceras? sp. indet. seems tobe related to forms like B. Polyplocum Roemer(Campanian of Germany, India, Tunisia, andMadagascar), B. punicus Pervinqui6re (adextral form from the Tunisian Campanian),and B. otsukai Yabe (1904, p. 14). It alsoresembles in ornamentation Nipponites mt-rabilis Yabe (1904, p. 20), of the JapaneseSenonian, which has a peculiar loosely coiledconch.

Bostrychoceras? sp. indet. was collectedfrom the Celendin formation, in bed 22 of the

Bambamarca section, where it is associatedwith Desmophyllites gaudama Forbes.

SUPERFAMILY PERISPHJNCTACEAEWEDEKIND, 1917

FAMILY OLCOSTEPEIANIDAE SPA:TH, 1924VALANGNTES SAYN, 1910

Valanginites broggii (Liss6n)Plate 40, figures 10-12

Sphaeroceras broggianus Liss6N, 1937, p. 153,p1. 1, figs. 1-2.

Three specimens belong to this species; oneof them (A.M.N.H. No. 27386/1) is a com-plete disc; the other two are slightly crushed.

MEASUREMENTSA.M.N.H. No.

27386:1D H D/H T D/T U D/U24 13 .54 17 .73 3 .12

DESCRIPTION: The conch is small, globose,very narrowly umbilicated. The whorl sectionis crescentic, depressed, with very high andperpendicular umbilical wall and abruptlyrounded umbilical shoulder. In the early partof the outer volution, the sides are very shortand merge evenly into the broad and semi-circular venter. Adorally, the sides becometaller and are almost subparallel, the ventro-lateral shoulder becomes noticeable, and thegently arched venter is as broad as the whorlitself (fig. 22). On the venter of the outer half-

FIG. 22. Valanginites broggii (Liss6n). Conchsection of specimen A.M.N.H. No. 27386:1;xi.whorl there are 27 fine, round-crested, evenlyspaced ribs, of which 10 are primary ribswhich start at the umbilical shoulder and run

in a prorsiradiate direction up to the ventro-

lateral shoulder where they bifurcate andcross over the venter; single ribs are inter-calated at the ventrolateral shoulder. Be-tween the diameters of 15 and 20 mm., theforking points of the ribs develop sharp,radially elongated tubercles; and between thediameters of 20 and 25 mm. on the siphonal

4371956


line, high, prominent, transversally elongatedtubercles appear every four or five ribs.REMARKS: Valanginites broggii is distin-

guished by the presence of both ventrolateraland siphonal tubercles. Valanginites angusti-coronatus Imlay (1938, p. 557) has bundles ofthree or four ribs starting from ventrolateraltubercles.OCCURRENCE: Valanginites broggsi is found

in the Carhuaz formation, in bed 6 of theCarhuaz section, where it is associated withother olcostephanid ammonites.

Spath (1924, p. .80) referred to the "Valan-ginites beds" of Colombia, and correlatedthem with the "Hoplitidan age" of the Eng-lish Valanginian. The present writer has beenunable to find any other reference to theseColombian Valanginites. Imlay (1940, 135)says that, although Valanginites is known inthe Hauterivian, it is mostly characteristic ofthe Valanginian. Kilian (1920, p. 12) assignsthe genus Valanginites to both the Valangin-ian and the lower Hauterivian.SUPERFAMILY DESMOCERATACEAE WRIGHT

AND WRIGHT, 1951FAMILY DESMOCERATIDAE ZITTEL, 1895

DESMOCERAS ZITTEL, 1884Desmoceras latidorsatum (Michelin)

Plate 41, figures 1-2Desmoceras latidorsatum (Michelin); SPATH,

1923-1943, vol. 1, p. 39, cum synon., pl. 2, figs.2a-b.One small specimen has been assigned to

this well-known and widely distributedspecies.

A.M.N.H. No.27387

MEASUREMENTS

D H D/H T D/T U D/U14 7.5 .53 8.5 .61 2.5 .18

DESCRIPTION: The conch is small, stout,narrowly umbilicated. The whorl section is

very inflated and depressed, with high andperpendicular umbilical wall and rounded butconspicuous umbilical shoulder. The sides are

slightly convex and subparallel to the end ofthe inner third, where the convexity in-creases, and thence they make an even curve

with the broadly arched and semicircularventer. Specimen A.M.N.H. No. 27387 has inthe last volution three widely spaced and

feeble constrictions which form a sinus in theperiphery. The suture is very frilled. It has adeep ventral lobe, a trifid first lateral lobe ofthe same depth, and bifid saddles which haverounded endings and decrease regularly insize.

REMARKS: Both Jacob (1908, p. 35) andSpath (1923-1943, vol. 1, p. 41) state thatDesmoceras latidorsatum is a very variableand small-sized species; the European occur-rences are no larger than 60 mm. in diameter.The Peruvian specimen agrees very closely

with the form described by Jacob (1908, pl.4, figs. 12a-b) as "var. b. de Kossmat," whichis characterized by the subparallel sides.OCCURRENCE: This species is found in the

Pariatambo formation, in bed 14 of thePariahuanca section, where it is associatedwith several species of Lyelliceras andOxytropidoceras.Desmoceras latidorsatum is a species with

world-wide distribution, appearing in thelower Albian and ranging into the Ceno-manian (Jacob, 1907, p. 312; 1908, p. 39;Spath, 1923-1943, vol. 1, p. 42).

Desmoceras chimuense, new speciesPlate 41, figures 5-8

This species is based on two specimens: theholotype, A.M.N.H. No. 27388:1, a com-plete, entirely septate steinkern, with theshell preserved only in a few patches aroundthe umbilicus, and specimen A.M.N.H. No.27388:2, also an entirely septate steinkern,which is slightly more than half of a disc.

A.MN.H. No.27388:127388:2

MEASUR§EMNTSD H D/H T D/T U D/U117 54.5 .47 44 .37 28 .2491 45.5 .50 38 .42 18 .24

DESCiuPTION: The conch is large, dis-coidal, fairly narrowly umbilicated. Thewhorl section is compressed, with a thick-ness of about four-fifths of the whorl height.The umbilical wall is high and perpendicular,almost overhanging; the shoulder is roundedbut distinct. The sides are flattened andparallel to the end of the middle third, wherethey increase in convexity and merge into theevenly arched, almost semicircular venter(fig. 23). The holotype shows five faint con-strictions in the last volution; they are radiate

438 VOL. 108


to the middle of the outer third, thence theybecome prorsiradiate and form a sinus on theventer. The suture line (fig. 23) is very frilledand has a deep and narrow ventral lobe, threetrifid lateral lobes on the sides, and a fourthlobe centered at the umbilical shoulder. Thesaddles are bifid, with rounded terminationsand regularly decreasing in size.

A

BFIG. 23. Desmoceras chimuense, new species.

Suture line (A) and conch section (B) of theholotype; X1.

REMARKS: Desmoceras chimuense is veryclose to D. latidorsatum var. complanataJacob (1908, p. 38) from which it is dis-tinguished because of its larger umbilicus,flattened sides, more broadly arched venter,and the steeper umbilical wall. Desmocerascolignoons Breistroffer (in Besairie, 1936, p.170), another similar form, has narrowerumbilicus, subconvex sides, and its constric-tions make a very strong, linguiform sinus inthe periphery. Desmoceras merriami Anderson(1938, p. 181), from the upper part of theHorsetown group of California, has narrowerumbilicus and less compressed whorl sectionthan D. chimuense. Desmoceras hyatti (Gabb,1877, p. 268), a Peruvian species of unde-termined stratigraphic position, lacks con-strictions, and its whorl section is almost asthick as high.

OCCURRENCE: Desmoceras chimuense wascollected from the lower Albian Inca forma-tion, in bed 6 of the Tamberia section, to-gether with several species of Parahoplites.

Desmophyllites gaudama (Forbes)Plate 41, figures 3-4

Ammonites Ga-udama FORBES, 1846, p. 113,pl. 10, fig. 3.Ammonites planulatus STOLICZEA, 1865 (1861-

1866), p. 134, p1. 67, fig. 1.Ammonites Hernensis SCHLttTER, 1871 (1871,

1876), P. 40, p1. 11, fig. 1.Puzosia Gaudama Forbes; KOSSMAT, 1898

(1895-1898), p. 115, p1. 16, figs. 2a-b, 3.Puzosia Gacudama Forbes; PERVINQUIkRE, 1907,

p. 161, pl. 6, figs. 33a-b.Puzosia Gaudama Forb.; BR1GGEN, 1910, p.

719.Desmoceras (Puzosia) sp. LtTHY, 1918, p. 50.Desmolphyllites ellsworthi KNECHTEL, 1947, i-n

Knechtel, Richards, and Rathbun, p. 128, pl.47, figs. 1-3.Three fragmentary specimens are referred

to this species.MEASuEIrS

A.M.N.H. No.27389

D H D/H T D/T U D/U65.5 27 .41 19 .29 22.5 .34

DEscRIPTION: The conch is medium insize, discoidal, fairly narrowly umbilicated.The whorl section is ovoid, compressed, withhigh and perpendicular umbilical wall andabruptly rounded umbilical shoulder. Thesides are gently vaulted, with maximum con-vexity about the end of the first fourth; they

FIG. 24. Desmophyllites gaudama (Forbes).Suture line of specimen A.M.N.H. No. 27389;x1.

converge towards the narrowly roundedventer. The greatest whorl thickness is nearthe umbilical shoulder and is about two-thirds of the whorl height. The inner volu-tions of the illustrated specimen (A.M.N.H.No. 27389) reveal four slender constrictionsper volution. The suture line (fig. 24) isstrongly frilled; it has a short ventral lobe,

4391956

a

440 BULLETIN AMERICAN MU!

three lateral lobes on the sides, and a fourthlobe on the umbilical wall; the saddles arebifid.

REMARiKS: The Peruvian specimens agreevery closely in all respects with the Indianspecimens illustrated by Forbes, Stoliczka,and Kossmat. The present writer, therefore,sees no reason why they should be given adifferent specific name, as was done byKnechtel (1947, in Knechtel, Richards, andRathbun, p. 128), only on the basis of theirwide geographic separation.

OccuRREuNcE: Desmophyllites gaudama isfound in the Celendin formation, in bed 22 ofthe Bambamarca section (A.M.N.H. No.27389), in bed 75 of the Polloc section(A.M.N.H. No. 27389/1), and in bed 3 of theSanta Clara section (A.M.N.H. No. 27389/2).In this last place, it is associated with Texan-ites sp. and Lenticeras lissoni. Briiggen reportsit from Otuzco (Cajamarca) and from SanPedro (Santa Clara).The holotype and Kossmat's specimens

come from the upper part of the Trichinopolygroup (India). PervinquRire reports D. gau-dama from the Tunisian Santonian.

SUPERFAMILY HOPLITACEAE SPATE, 1922FAMILY PARAHOPLITIDAE SPATH, 1922

PARAHOPLICTS ANTuIULA, 1900Parahoplites nicholsoni,l new species

Plate 42, figures 11-12Three specimens belong to this new species;

the holotype (A.M.N.H. No. 27390) is a com-plete disc 110 mm. in diameter; the last three-fourths of the outer volution belong to thebody chamber. Specimen A.M.N.H. No.27390/1 is an entirely septate whorl fragmentbelonging to an individual at least 160 mm.in diameter.

MEASUEMENTSA.M.NE. No.

27390D H D/H T D/T U D/U110 47 .43 38 .35 37 .34

DESCRIPTION: The conch is large, dis-coidal, fairly widely umbilicated. The whorlsection is subtrapezoidal, compressed, withthe greatest thickness near the umbilicalshoulder. The whorls grow in height more

quickly than in thickness. The umbilical wallis high and perpendicular or even overhang-

1 Named in honor of Prof. Carlos Nicholson.

UM OF NATURAL HISTORY VOL. 108

ing; the umbilical shoulder is rounded butvery distinct. The sides are flattened andslope gently towards the venter, tending tobecome parallel in the latter stages. Theventrolateral shoulder is broadly rounded;the venter is broad and subflattened in theearly whorls but becomes evenly arched inthe outer whorls. On the venter of the outerwhorl of the holotype, there are 64 round-crested, evenly spaced, equidimensional ribs,of which 21 are primary ribs.At a radius of 25 mm., the earliest observa-

ble one, the primary ribs are widely spaced,start in the umbilical wall, and become in theumbilical shoulder very prominent, subacute,and slightly prorsiradiate. At about the mid-dle third of the sides, they are attenuated andbifurcate. The branches become again strongin the outer third, where they take a forwardslant before crossing the venter. Single ribsare intercalated in the middle third; theseribs have, on the outer third and on theventer, the same size, shape, and attitude asthe primary ones.At a radius of 30 mm., the umbilical swell-

ings of the primary ribs are very conspicuousand could well be described as sharp-edged,radially elongated, high tubercles; there aretwo intercalated ribs instead of a single one,and all the ribs are not so attenuated in themiddle third as they were in earlier stages.At a radius of 40 mm. the umbilical swell-

ings have achieved their maximum develop-ment; they are high, sharp-crested, elongated,and extend beyond the end of the inner thirdat the end of which they bifurcate. There isagain only one intercalated rib. Further

FIG. 25. Parahoplites nicholsoni, new species.Suture line of the holotype; XI.

growth is marked by the reduction of theumbilical tubercle which becomes blunt andtends to disappear, and also by the disappear-ance of the forward slant of the ribs near theventer. The ribs become straight, slightlyprorsiradiate, and more closely crowdedthan in earlier stages. The intercalated ribsbegin early in the middle third. In specimen

'SET


A.M.N.H. No. 27390/1, at about 160 mm. indiameter, the ribs also become attenuated.The suture line (fig. 25) has a ventral lobe

with parallel sides and a deeper, trifid, firstlateral lobe. The first lateral saddle is verybroad and divided by a small lobule into twobranches, the outer one being larger. A sec-ond, small, lateral lobe is already in the um-bilical wall.REMARKS: Parahoplites nicholsoni differs

from P. melchioris, the genotype, because ofits larger umbilicus, very pronounced um-bilical swellings, very uniform forking of theribs, and the taller whorl section. Para-hoplites grossouvrei Jacob (1905, p. 409) fromthe Clansayes beds of France resembles P.nicholsoni in shape and ornamentation but isdistinguished by its smaller umbilicus, thechevron sinus formed by the ribs on theventer, and because of the early developmentof the ornamentation.OCCURRENCE: This species is fairly abun-

dant in the Inca formation, in bed 6 of theTamberia section (A.M.N.H. No. 27390/1)and in bed 50 of the Sunchubamba section(A.M.N.H. No. 27390), where it is associatedwith Desmoceras chimuense and with Knemi-ceras ollonense.

Parahoplites quilla, new speciesPlate 42, figures 1-8

This species is erected on the basis of threesmall whorl fragments. The holotype isA.M.N.H. No. 27391:1.

DESCRIPTION: The conch is small and dis-coidal. The costal whorl section is subrectan-gular to subtrapezoidal, compressed, withhigh and perpendicular umbilical wall androunded but distinct umbilical shoulder. Thesides are subflattened and almost parallel inthe inner half of the sides but become broadlyarched and converging in the outer half.The ventrolateral shoulder is rounded butdistinct. The venter is broad and subflat-tened. The intercostal whorl section is similar,although with more broadly rounded ventro-lateral shoulders and more arched venter.The ribbing is fine, dense, and flexuous. Theprimary ribs begin almost at the umbilicalseam and are strong and prorsiradiate to theend of the inner third, where they usuallybifurcate. The branches, or the intercalatedribs that begin here, are less prorsiradiate but

swing forward again before crossing theventer. On the venter, all the ribs have thesame size and shape, and are narrower thanthe interspaces.REMARKS: Parahoplites quilla differs from

most other Parahoplites by its distinct ventro-lateral shoulders, although they are nottuberculated as in Hypacanthoplites. The verydense and fine ribbing and the branching ofthe ribs resemble those of some species ofRhytidoplites described by Scott (1940, p.1034) from the Texan middle Albian.OCCURRENCE: This species is found in the

Inca formation, in bed 50 of the Cajamarcaformation.

Parahoplites inti, new speciesPlate 42, figures 9-10

Two specimens are the basis of this species.Specimen A.M.N.H. No. 27392, the holotype,is a half disc which lacks the inner whorls.

DESCRIPTION: The conch is discoidal,fairly narrowly umbilicated. The whorl sec-tion is compressed, ovoid, with low umbilicalwall and rounded but very distinct umbilicalshoulder. The sides are subflattened and sub-parallel; the ventrolateral shoulders arebroadly rounded, and the venter is evenlyarched. The greatest whorl thickness, aboutthe middle of the sides, is about three-fourthsof the whorl height (fig. 26). On the venter ofthe outer half-whorl, there are 26 rounded,strong, evenly shaped ribs, of which 12 areprimary ribs which begin in the umbilical

FIG. 26. Parahoplites inti, new species. Conchsection of specimen A.M.N.H. No. 27392; X1.

wall and are prorsiradiate in the inner third,at the end of which some fork, intercalatedribs appear, and all become less prorsiradiate.

REMARK:S: Parahoplites inti is distinguishedfrom P. quilla by the lack of a flattenedventer, more compressed whorl section andcoarser ribbing. A very similar species is P.subcampischei Sinzow (1907, p. 463) which

1:956 AA1


has a thicker whorl section, more uniformforking of the ribs, and ribs that form apronounced forward sinus in the periphery.

OCCURRENCE: Parahoplites inti is found inthe Inca formation, in bed 50 of the Caja-marca section, associated with P. quilka.

FAMILY DOIUVILLEICERATIDAE SPATH,1923

DOuLLEICERAS De GRossouvRE, 1894Douvmeiceras monile (Sowerby)

Plate 43, figures 1-4Douvileiceras monile Sowerby; SPATH, 1923-

1943, vol. 1, p. 72, cum synon., pl. 4, fig. 4, pl. 5,figs. 5a-c.

Several specimens, including three entirediscs, are assigned to this well-known andwidely distributed species.

MEASMENTSA.M.N.H. Nos.

2739327393/127393/2:1

D H46 18.544 1955 22

D/H T D/T U D/U.40 23 .50 18 .39.43 24 .54 16 .35.40 25 .45 21 .38

DESCRIPTION: The conch is stout, mediumin size, fairly widely umbilicated. The whorlsection is depressed, reniform, inflated, withvery steep umbilical wall and rounded um-bilical shoulder. The sides are convex andgently merge into the broadly rounded venter(fig. 27). The outer volution has 22 to 25strong, round-crested, multituberculate ribswhich begin at the umbilical shoulder and areslightly rursiradiate in the outer half of thesides. On the venter, the ribs are slightly at-tenuated and more broadly rounded.At a radius of 5 mm. (A.M.N.H. No.

27393), the whorl section is coronate; thereare very faint, narrow, very widely spacedribs which bear faint tubercles on both sidesof the siphonal line and on the lateral anglesof the coronate whorl section.At a radius of 9 mm., the ventral tubercles

are strong and spinate, the first lateral tuber-cles occupy the ventrolateral shoulders, anda new pair of tubercles appears at the um-bilical shoulders of the already reniformwhorl section. A few intercalated ribs bearonly ventral tubercles.

Further growth is marked by the increasedcrowding of the ribs, which become strong,

FiG. 27. Douvilleiceras monile (Sowerby). Conchsection of specimen A.M.N.H. No. 27393; X1.

and by the appearance of new rows of tuber-des, usually by the splitting of the ventraltubercles. At a radius of about 25 mm., theribs are strong, slightly narrower than theinterspaces, and bear six tubercles on eachside; the ventral tubercles are the mostconspicuous, while all the others are of aboutthe same size. Thence, all the tubercles tendto become fainter.REMARKS: Douvilkiceras monile stands be-

tween the closely related D. mammillatum(Schlotheim) and D. solitae (d'Orbigny, 1853,p. 211), both as to the number of ribs pervolution and as to the size of the umbilicus(table 1).

Douvilleiceras monile differs from D. mai-millatum, also, by the lack of prominence ofthe lateral tubercles and because after adiameter of 45 mm. all the tubercles are smalland equal in size.OCCURRENCE: Douvilleiceras monile is found

in the lower middle Albian Chulec formation,in bed 12 of the Pariahuanca section(A.M.N.H. No. 27393/2), associated withProtanisoceras blancheti, in bed 21 of thePomachaca section (A.M.N.H. No. 2739/1),

TABLE 1COMPARISON OF DouVilleiceras mammillotum, Douvilleiceras monile, AND Douvilleiceras solitae

D. mammilatumNumber of ribs per volution 18- 25D/U .30-.33

D. tnonile

30- 35.34-.40

D. solitae

40.44

VOL. 108442


and in bed 58 of the Cajamarca section(A.M.N.H. No. 27393), associated withKnemiceras raimondii, Lyelliceras lyelli,and Parengonoceras sp.

Douvlleiceras monile is one of the charac-teristic species of the Douvilleiceratan age ofthe English (Spath, 1923-1943, vol. 2, p. 688)and French (Breistroffer, 1947, p. 40) Albian.

FAMILY SCHLOENBACHIIDAE SPATH,1925

FORBESICERAS KOSSMAT, 1898Forbesiceras sp. indet.

A single, poorly preserved fragment(A.M.N.H. No. 27394) belongs to this genus.It is mentioned here because no representa-tives of Forbesiceras have previously been re-corded in South America.

DESCRIPTION: The fragment belongs to adiscoidal, flat, extremely narrowly umbili-cated conch. The whorl section (fig. 28) isvery compressed, lanceolate; the greatestthickness is at the end of the inner third andis less than one-third of the whorl height.The sides are gently convex in the innerthird, and thence they converge with littleconvexity towards the narrow, truncatedventer. The ventrolateral shoulder is angular.The specimen is weathered, and no ornamen-tation is discernible. The suture is typical ofForbesiceras, very frilled and complex. All the

r FIG. 28. Forbesiceras sp. indet. Conch section

of specimen A.M.N.H. No. 27394; X1.

saddles, especially the first one, are deeplyincised by a frilled medial lobe.Specimen A.M.N.H. No. 27394 seems to

belong to a species very closely related toForbesiceras kagilliertianum (d'Orbigny).OccuRRENCI: Forbesiceras sp. indet. occurs

in the upper Cenomanian Romir6n forma-tion, in bed 44 of the Celendin section, asso-ciated with Lissoniceras mermeti, Acantho-ceras chasca, and Neolobites k1mmeli.The genus Forbesiceras is found in the

Cenomanian of Tunisia (Pervinquiere, 1907,p. 106), in the Ootatoor group of India, andin the Varians zone of the English Cenoman-ian (Wright and Wright, 1951, p. 23).

FAMILY ENGONOCERATIDAE HYATT, 1900ENGONOCERAS NEUMAYR AM UBLIG, 1881

Engonoceras sp. indet.Plate 43, figures 11-12

One complete, fractured steinkern, whichwas at least 340 mm. in diameter, is referredto Engonoceras. The outer half-whorl belongsto the body chamber.

A.M.N.H. No.27395

MEASMREMENTSD H D/H T D/T U D/U285 165 .58 72 .25 15 .05

DEsCRIPTION: The conch is large, dis-coidal, flat, with almost closed umbilicus.The whorl section is extremely high and com-pressed, lanceolate, with very low and indis-tinct umbilical wall and broadly roundedumbilical shoulder. The greatest thickness isbelow the middle of the sides and is less thanhalf of the whorl height. The sides are gentlyconvex and converge towards the narrow,truncated venter; the ventrolateral shoulderis sharp, and angular to a diameter of 180mm. where it becomes rounded. At thisdiameter, the venter also changes from flat tonarrowly rounded. The umbilical shoulderand the sides are smooth. The ventrolateralshoulders are furnished with numerous small,spirally elongated tubercles. The suture ispseudoceratitic, with numerous massive,quadrate saddles which have a small mediallobe and entire margins. The lobes are

strangulated and denticulated.REMARKS: The suture line of Engonoceras

sp. indet. is comparable to that of E. com-

1956 AA2


plcatum Hyatt (1903, p. 175) which hasthree rows of tubercles. Most species ofEngonoceras have sutures with entire saddlesand are ornamented with three or two rowsof tubercles. Engonoceras grimsdalei Spath,from the Dispar zone of the British upperAlbian, has similar shape and ornamentationbut flattened sides and entire saddles.OCCURRENCE: Engonoceras sp. indet. is

found in the upper Albian-lower CenomanianYumagual formation, in bed 101 of theCajamarca section.

Engonoceras is a common genus in theAlbian and Cenomanian of Texas, Mexico,North Africa, and the Middle East.

PAREIGONOCERAS SPATH, 1924Parengonoceras pernodosum (Sommermeier)Plate 44, figures 3-4; plate 45, figures 1-5

P2acenticeras pernodosum SOMMERMEIER, 1910,p. 331, p1. 7, fig. 1.

Five well-preserved steinkerns includingone complete disc and two half discs are re-ferred to this species.

A.M.N.H.Nos.

27396:127396:227396/1:1

MEASEMENTS

D D D/H T D/T U D/U

91111

149.5

48 .53 28 .31 11.555 .50 37 .33 1571.5 .48 56 .37 21

.12

.13

.14

DESCRIPTION: The conch is large, discoidal,very narrowly umbilicated. The whorl section(fig. 29) changes from compressed triangular,with narrow truncated venter, in the earlywhorls to compressed ovoid, with roundedventer, in maturity. In the outer half-whorlof the largest available specimen (A.M.N.H.No. 27396/1:1) there are four conspicuousrows of tubercles: one row of four strong,

prominent, radially elongated tubercles near

the end of the first third; a second row ofeight, less prominent, radially elongatedtubercles at about the middle of the sides;a third row of 16, less prominent, roundedand small tubercles at about the middle of theouter third; and, finally, a fourth row ofnumerous spirally elongated tubercles at theventrolateral shoulders; adorally, they tendto be obliterated.The suture has large quadrate saddles

which have a medial lobe and denticulatedmargins with phylloid, rounded terminations;the lobes are rather narrow and denticulated(fig. 29).Between the diameters of 7 and 40 mm.,

the whorl section changes from triangular,with a narrow truncated venter, to a veryhigh whorl section, with subparallel sides andflat or even concave venter. Growth ismarked in height. At a diameter of 40 mm.,there is a row of pointed tubercles, slightlyelongated radially, just above the umbilicalshoulder, a second row of smaller tuberclesby the middle of the sides, and a third row ofvery sharp, spirally elongated tubercles atthe ventrolateral shoulders. Low, broad, falci-form ribs connect the three rows of tubercles;some of the medial tubercles serve as startingor as forking points of the ribs.

Between the diameters of 40 and 80 mm.growth is characterized by a decrease of thediameter-height ratio and an increase of thediameter-thickness ratio; the ventrolateralshoulders change from angular to roundedand indistinct; the venter changes from flatto broadly arched; and the sides bulge toproduce an ovoid whorl section with steepumbilical wall, conspicuous umbilical shoul-der, broadly arched sides, and a roundedventer. By a diameter of 80 mm., the falci-form ribs become fainter, the tubercles aremore widely spaced, and a fourth row ofpointed tubercles appears at about the middleof the outer third, between the second row ofmediolateral tubercles and the ventrolateralones.

Between the diameters of 80 and 150 mm.,the ventrolateral shoulders become obliter-ated, the ventrolateral tubercles (fourthfrom the umbilicus, third in order of appear-ance) tend to vanish, and the venter isbroadly arched.REMARKS: Parengonoceras pernodosum re-

sembles P. ebrayi de Loriol (1882, p. 7), thegenotype, from the Douvilleiceras zone ofEurope, in the suture and the general patternof ornamentation, but is distinguished byhaving less flattened sides and by the earlierappearance of the ornamentation. In P.ebrayi the umbilical tubercles appear onlyafter a diameter of 150 mm.The suture illustrated by Sommermeier

(1910, fig. 13) is somewhat misleading, for it

VOL. 108AAA


I

A

C

0IB

D

FIG. 29. Parengonoceras pernodosum (Sommermeier). A, B, C. Suture lines of specimensA.M.N.H. Nos. 27396:2, 27396:1, and 27396/1:1. D, E. Conch sections of specimensA.M.N.H. Nos. 27396/1:2 and 27396:2. All XI.

does show the pronounced rounding of thesaddle terminations.

OCCURRENCE: This species occurs in themiddle Albian Crisnejas formations, in bed 9of the Celendin section, associated with P.tetra-nodosum, P. haasi, and Knemicerasattenuatum, in bed 20 of the Crisnejas section(A.M.N.H. No. 27396/1:1), in bed 2 of theUchupata section, associated with K. syria-cun. It is also found in the Chulec formation,in bed 11 of the Lajas section.The holotype, described by Sommermeier,

comes from northern Cajabamba.In the Chulec formation, there ar-e speci-

mens of Parengonoceras sp. which attain morethan 80 mm. in diameter and which could notbe collected nor specifically determined.Parengonoceras guadaloupaeforme (Sommer-

meier)Plate 44, figure 2

Placenticeras guadalupaeforme SOMMERM1IER,1910, p. 337, p1. 7, fig. 2, p1. 8, figs. 1-2.This species is represented by a single

steinkern (A.M.N.H. No. 27397), a fragmentof the body chamber belonging to an indi-vidual at least 130 mm. in diameter.

Parengonoceras guadaloupaeforme is very

1956 445


similar to P. pernodosum and differs only bythe very strong and conspicuous developmentof the ornamentation, particularly of theinner three rows of tubercles which are con-nected by strong falciform ribs. The whorlsection is subrectangular, not ovoid as in P.pernodosum.

OCCURRENCE: The specimen was collectedfrom the lower middle Albian Chulec forma-tion, in bed 71 of the Cajamarca section.Sommermeier. reported this species fromHualgayoc, El Monton, and Cachachi (Con-debamba).

Parengonoceras tetranodosum (Liss6n)Plate 43, figures 5-10; plate 44, figure 1

Ktnemiceras tetranodosum Liss6N, 1925, p. 25,pl. 2, fig. 3.

Six specimens (two complete discs, two halfdiscs, and two smaller whorl fragments) arereferred to this species.

A.M.NH. Nos.2739827398:227398:3

MEASVRMENTS

D H D/H T37.5 20 .53 1257 27.5 .48 17.571 35 .49 20.5

D/T.32.31.29

U D/U6 .16

10 .1712 .17

DESCRIPTION: The conch is discoidal, verynarrowly umbilicated. The whorl sectionchanges from compressed triangular, withtruncated venter, in the early whorls to com-pressed polygonal in the later ones. Thereare four rows of tubercles that begin veryearly in the ontogeny, and falciform ribswhich are prominent between the diametersof 20 and 40 mm. but which vanish beyondthe later diameter. The suture is as in P.pernodosum, although apparently the lobes

FIG. 30. Parengonoceras tetranodosum (Liss6n).Suture line,of specimen A.M.N.H. No. 27398:4;xl.

are not so strangulated and the margins ofthe saddles are not so denticulated (fig. 30).

Between the diameters of 12 and 20 mm.,

the whorl section is very high and com-

pressed, triangular, and truncated by a

narrow subconcave venter; the sides are

gently vaulted and converge towards thenarrow, truncated venter. Just above theumbilical shoulder there is one row of high,pointed tubercles which are the startingpoints of prorsiradiate ribs. In the outerthird, the ribs swing forward and end in verysharp, spirally elongated tubercles at theventrolateral shoulders. Between the primaryribs there are two or three intercalated ribswhich start at about the middle of the sides.At a diameter of 35 mm. a middle row of

tutbercles appears; they serve as forkingpoints for the low ribs.Between the diameters of 35 mm. and 45

mm. the maximum whorl thickness movesfrom the umbilical shoulder to the middle ofthe sides; the umbilical wall is narrow andsteep and the shoulder is broadly rounded.The sides are parallel between the two innerrows of tubercles but converge from themiddle row towards the broadly truncatedventer. The ribs that connect the tuberclesbecome fainter, and the tubercles tend to bemore widely spaced. At a diameter of 45 mm.a fourth row of tubercles appears at about themiddle of the outer third, and some of themserve as forking poinlts for very low and broadribs.REMARKS: Parengonoceras tetranodosum is

closely related to P. pernodosum but is dis-tinguished because of its polygonal whorl sec-tion, its smaller size, and the early develop-ment of the ornamentation. Also, the saddlemargins of the suture of P. tetranodosum arenot so denticulated as in pernodosum, resem-bling, thus, the suture of some species ofKnemiceras.OCCURRENCE: This species is found in the

Crisnejas formation (zone of Knemicerasraimondii), in bed 9 of the Celendfn section,associated with P. pernodosum and Knemi-ceras attenuatum. Liss6n's holotype is fromCajamarca.

Parengonoceras haasi,1 new speciesPlate 46, figures 1-6

This species is erected on the basis of fivesteinkerns; the largest (A.M.N.H. No.27399:1) is selected as the holotype.

I The specific name is given in honor of Dr. OttoHaas.

446 VOL. 108

BENAVIDES: CRETACEOUS SYSTEM IN PERU 447MEASMUEMENTS

A.M.NH.Nos. D H D/H T27399:4 56.5 30.S .54 1427399:3 61 32 .53 1427399:2 70.5 36 .51 1727399:1 80 42 .53 22.5

D/T.25.23.24.28

U4.5666

D/U.08.09.08.07

spiral]laterasamefold-liof tutUp

DESCRIPTION: The conch is flat, discoidal, sectiovery narrowly umbilicated. The whorl section angul,(fig. 31) changes from slender, very high and wallcompressed, triangular, with a very narrow shoulk

A B

"

C

D

lly elongated tubercles at the ventro-I shoulders, which appear at about thetime as the umbilical tubercles. Faint,ike falciform ribs connect the four rowsbercles.to a diameter of 40 mm., the whorl

)n is very high and compressed, tri-lar, with narrow and steep umbilicaland rounded but distinct umbilicalder. The sides are broadly arched and

I

EFIG. 31. Parengonoceras haasi, new species. A, B, C.

Suture lines of specimens A.M.N.H. Nos. 27399:2,27399:3, and 27399:1 (holotype). D, E. Conch sectionsof the holotype at two different radii. All X 1.

truncated venter, to very compressed, high,and ovoid, with the greatest thickness justabove the middle of the sides. There are fourrows of tubercles: one row of prominent,radially elongated tubercles near the end ofthe inner third which appear at a diameterof 50 mm.; a second row of similar tuberclesjust above the middle of the sides whichappear just after the tubercles of the firstrow; a third row of blunt and rounded tuber-cles at about the middle of the outer thirdwhich appear at a diameter of 75 mm.; anda fourth row of more numerous, sharp,

converge towards the very narrow and flatventer with sharp, angular ventrolateralshoulders. The greatest thickness is near theumbilicus and is less than half of the whorlheight.

Further growth is marked by a sharpdecline in the diameter-height ratio and anincrease in the diameter-thickness ratio. At adiameter of 80 mm., the whorl section is veryhigh and compressed, ovoid, with low umbili-cal wall, and rounded but distinct umbilicalshoulder. The sides are broadly vaulted,somewhat flattened about the middle of the

1956


sides, and converge towards the narrow,subconcave venter. The greatest thickness isjust above the middle of the sides and isabout half of the whorl height.REMARES: Parengonoceras haasi differs

from all other species of Parengonoceras by itsslender whorl section, the late appearance ofthe ornamentation, and by the lack of con-spicuous falciform ribs.OCCURRENcE: This species is found in the

Crisnejas formation (zone of Knemicerasraimondii), in bed 9 of the Celendmn section,together with P. pernodosum, P. tetranodo-sum, and Knemiceras attenuatum.Parengonoceras? champaraense,1 new species

Plate 51, figures 8-9This species is based on a single, fractured,

completely septate steinkern (A.M.N.H. No.27848).

MEASUIENTSnAMN.H. No. D H D/H T D/T U D/U

27848 139 76 .55 39 .29 14 .09

DEsCRiPTION: The conch is large, dis-coidal, flat, very narrowly umbilicated. The

less than one-half of the whorl height. Thereare three rows of tubercles: one row of tuber-cles elongated in a prorsiradiate directionnear the end of the inner third, which appearat a radius of 30 mm.; a second row of low,pointed tubercles which appear at a radiusof 40 mm., and which quickly become faintand inconspicuous; and a third row of small,numerous, spirally elongated tubercles whichform out of the sharp angular ventrolateralshoulders at a radius of 45 mm. and becomevery faint at about a radius of 65 mm. The su-ture is fairly complex (fig. 32). The saddlesare large, subquadrate, divided by a deepmedian lobule and with extremely prominentphylloid marginal denticulations; the lobesare strangulated, have a rounded outline, andare digitated.REMARKS: Parengonoceras? champaraense

bears some resemblance in shape and orna-mentation to some species of Knemiceras. Thesuture, however, is definitely that of Parengo-noceras; in fact, the rounding of the saddleterminations is more prominent and con-spicuous in P.? champaraense than in any ofthe other species of Parengonoceras. The pres-

A

f

BFIG. 32. Parengonoceras? champaraense, new species.

Suture lines of the holotype (A and B).

whorl section is very high and compressed,with narrow and steep umbilical wall androunded but conspicuous umbilical shoulder.The sides are gently convex, subparallel tothe end of the middle third; thence theygently converge towards the narrow, flat, andtruncated venter. The greatest whorl thick-ness is at about the middle of the sides and is

1 Named after Nevado Champari, east of which isthelocalit where the hotoe wasco1lected

ence of only three rows of tubercles dis-tinguishes this species from the other speciesof Parengonoceras characterized by four rowsof tubercles.OCCURRENCE: This species is found in the

lower middle Albian Chulec formation, inbed 8 of the Sihuas section, associated withDouvilleiceras mammillatum, Prolyellicerasperuvwnum, Brancoceras aegoceratoides,Knemiceras raimondii, Knemiceras tri-angulare, and K. raimondii tardum.

A448 VOL. 108

pI


KNEMICBRAS BOM, 1898VeIceras attenuatum (Hyatt)

Plate 46, figures 7-10Buchiceras atteinuatum HYATT, 1875, p. 372.Glottoceras attenuatum HYATT, 1875, p. 372

(footnote).Knemiceras attenuatum (Hyatt); HYATT, 1903,

p. 151, curm synon., p1. 17, figs. 13-15.Knemiceras attenuatun-typicum SOMMERMEIER,

1910, p. 341.Knemiceras (Gkottoceras) typicum Sommermeier;

BREISTROFFER, 1952, p. 2633.

Five steinkerns, including four completediscs and one half disc, are assigned to thisspecies.

MEASIRA NTS

A.M.NM. Nos. D27849:1 5227849/1 5227849/2 55.527849/3 63

H D/H T27.5 .53 17.527.5 .53 1629.5 .53 1836.5 .58 19

D/T U.34 7.31 6.32 7.30 6.5

D/U.14.12.13.10

DESCRIPTION: The conch is discoidal, flat,very narrowly umbilicated. The whorl sec-tion (fig. 33) is very high and compressed,triangular, with steep umbilical wall androunded umbilical shoulder. The sides con-verge with gentle convexity towards thenarrowly truncated venter; the ventrolateralshoulders are angular. The greatest thicknessis just above the umbilical shoulder and isabout two-thirds of the whorl height. Thereare three rows of tubercles: one row of highradially elongated tubercles just above theumbilical wall which appear before a radius of15 mm.; a second row of more numerous, lessprominent, elongated tubercles above themiddle of the sides which appear at a radiusof 20 mm.; and a third row of sharp, spirallyelongated tubercles at the ventrolateralshoulders which begin at a radius of 15 mm.,and which may be corresponding or not. Low,falciform ribs connect the three rows oftubercles; some of them issue or fork out ofthe middle tubercles. The ribs are more con-spicuous between the radii of 15 and 20 mm.The suture (fig. 33) has quadrate saddleswhich have a median small indentation andentire margins. The lobes are narrow,strangulated, and digitated.

REMARyS: Knemiceras raimondii and itsrelatives are distinguished from K. attenua-

tAU

BY)FIG. 33. Knemiceras attenuatum Hyatt. Suture

line (A) and conch section (B) of specimenA.M.N.H. No. 28849:1; Xl.

tum because early in the ontogeny the whorlsection changes from triangular to rec-tangular. Among other species with triangularwhorl sections, K. gabbi and K. ollonenseare larger in size and have only two rows oftubercles.OCCURRENCE: Knemiceras attenuatum is a

common ammonite in the lower middleAlbian Chulec formation (zone of Knemicerasraimondii).

A.M.N.H.Nos.

2784927849/127849/227849/3

BED

5270823

SECTION SPENo.OFSEcTIONSPECIMENSSunchubambaCajamarcaSihuasPomachaca

2111

In the Sihuas section, it is associated withK. raimondii, Douvilleiceras monile, andProlyelliceras peruvianum. Hyatt's holotypecomes from Celendin.A number of specimens from the Middle

East (Bass6, 1937, 1940) have been referredto K. attenuatum, but the present writer doesnot agree with these identifications.

Knemiceras attenuatum spinosum(Sommermeier)

Plate 46, figures 11-12Knemiceras attenuatum-typicum var. spinosa

SOMMERMEIER, 1910, p. 347, pl. 9, fig. 2.

1956 AAO


One small, completely septate, fairly well-preserved steinkern (A.M.N.H. No. 27850) isreferred to this species.

MEASUREENTSA.M.NEI. No.

27850D H D/H T D/T U D/U48 24 .50 17 .35 6.5 .13

DESCRIPTION: The conch is small, dis-coidal, very narrowly umbilicated. Thewhorl (fig. 34) section is very high, com-pressed, triangular, with rounded umbilicalshoulder and high umbilical wall. The sidesare gently vaulted and converge towards the

FIG. 34. Knemiceras attenuatum(Sommermeier). Conch section ofA.M.N.H. No. 27850; XI.

spinosumspecimen

narrow, truncated venter; the ventrolateralshoulders are angular. There are three rows oftubercles: one row of tubercles just above theumbilical shoulder which appear at a radiusof 15 mm. as fold-like swellings; at about a

radius of 22 mm., they quickly develop intoprominent, high tubercles which are elon-gated in a prorsiradiate direction; the secondrow of tubercles is just above the middle ofthe sides; they are elongated in a prorsi-radiate direction, are less prominent thanthe umbilical ones, and appear at about a

radius of 22 mm.; the third row consists ofnumerous spirally elongated tubercles whichappear at a radius of 15 mm. Falciform, fold-like extensions of the tubercles connect them.The suture is similar to that of K. attenuatum.REMARKS: Knemiceras attenuatum spino-

sum differs from K. attnuatum only by itsslightly thicker whorl section and the earlyand prominent development of the tubercula-tion.

The holotype, described by Sommer-meier, differs from specimen A.M.N.H. No.27850 (pl. 46, figs. 11-12) by the spinosedevelopment of the ornamentation. Knemi-ceras libertandense Breistroffer (K. attenua-tism Hyatt; Douvill6, 1906, pl. 3, figs. 1-la)is similar in whorl section and ornamentationto K. attenuatum spinosum but differs by thelack of a middle row of tubercles.OCCURRENCE: This subspecies is found in

the lower middle Albian Chulec formation,in bed 23 of the Pomachaca section, associ-ated with K. attenuatum and Douvilleicerasmonsle.

Knemiceras syriacum (von Buch)Plate 47, figures 4-S5

Ammonites syriacus VON BUCH, 1849, p. 20, pl.6,figs. 1-3, pl. 7, fig. 1.Knemiceras syrsacum von Buch: BASSt, 1937,

p. 167, cum synon., pl. 8, fig. 5, pl. 9, fig. 3, pl.lO,fig. 2, pl. 11, fig. 3.Two specimens are assigned to this species.

MEASUMENTSA.M.N.H. No.

27851D H D/H T D/T U D/U53 27.5 .52 25 .47 9 .06

DESCRIPTION: The conch is small, stout,discoidal, narrowly umbilicated. The whorlsection is slightly compressed, with thegreatest thickness near the umbilical shoulderwhich is very broadly rounded. The sides aresubflattened and converge towards thebroadly truncated venter. Just above theumbilical shoulder of the outer volution,there are nine pointed tubercles which areelongated im a prorsiradiate direction and arethe starting points of conspicuous, broad,low, prorsiradiate ribs. By the middle of thesides, the ribs become radial, sometimes fork,and intercalated ribs also appear. All the ribsend in spirally elongated, strong, blunt tuber-cles at the ventrolateral shoulders. In theouter volution, there are 24 ventrolateraltubercles. The suture has massive, sub-quadrate saddles which have a small mediannotch and slightly denticulated margins. Thelobes are strangulated and digitated (fig. 35).REMARKS: The Peruvian specimens agree

in shape, ornamentation, and dimensionswith von Buch's holotype. The suture, how-ever, has the saddles with slightly denticu-lated margins, a feature which Basso thinks

VOL. 108450


is characteristic of K. uhligi, a very similarspecies distinguished by its more compressedwhorl section. Knemiceras gabbi is similar toK. syriacum in shape and ornamentationbut is distinguished by its larger size andmore flattened sides.

FIG. 35.Suture linex1.

'~~~Knemiceras syriacum (von Buch).of specimen A.M.N.H. No. 27851;

OCCURRENCE: Knemiceras syriacum isfound in the lower middle Albian Chulec for-mation, in bed 71 of the Cajamarca section(A.M.N.H. No. 27851), and in the Crisnejasformation, in bed 3 of the Uchupata section(A.M.N.H. No. 27851/1). In both places it isassociated with Parengonoceras pernodosum.

Knemiceras gabbi HyattPlate 47, figure 3

Ammonites attenuatum Hyatt; GABB, 1877, p.264, pl. 36, figs. la-b.

Placenticeras attenuatum Hyatt; PAULC:RE, 1903,p. 284, fig. 4.

Knemiceras gabbi HYATT, 1903, p. 152, p1. 18,figs. 1-3.

Knemiceras gabbi Hyatt; LIss6N, 1908, p. 2a,pl. 2.

Knemiceras bassleri KNECETEL, 1947, in Knech-tel, Richards, and Rathbun, p. 90, pl. 17, figs. 1-2.

Two specimens are available for study.Specimen A.M.N.H. No. 27852 (pl. 47, fig. 3)is a steinkern 180 mm. in diameter; the outerthree-quarters of the last volution belong tothe body chamber.

DESCRIPTION: The conch is large, dis-coidal, very narrowly umbilicated. The whorlsection is compressed, truncated triangular.The greatest thickness is very close to theumbilical shoulder and is about three-fourthsof the whorl height. The sides are sub-flattened and converge towards the truncatedventer which is between one-half and one-third of the whorl thickness. Above theumbilical shoulder there is a row of five tosix strong, pointed, broad-based tubercleswhich are the starting points of low, broadribs. In the outer third, the ribs become moreconspicuous, some intercalated ones appear,

and all end in strong, spirally elongatedtubercles at the ventrolateral shoulders. Thesuture is similar to that of K. attenluatum.REMARKS: Gabb's original illustration of

the holotype, reproduced later by Hyatt,was misleading. Fortunately, Lisson pub-lished a much better picture of the samespecimen.

Knemiceras gabbi is distinguished from K.attenuatum by its larger size, the propor-tionally thicker whorl section, and by thepresence of only two rows of strong tubercles.Knemiceras syriacus, K. ukligi, and K.compressum are very similar species whichdiffer from K. gabbi because of their smallersize and subdued tuberculation. Knemiceraslibertadense, on the other hand, differs fromK. gabbi by the extremely strong develop-ment of its umbilical tubercles.Sommermeier (1910, p. 348) badly con-

fused the identity of K. gabbi. The specimendescribed by him as Knemiceras attenuatum-gabbi has strongly convex sides and has athird row of tubercles in the outer third.The specimen described by Knechtel

(1947, in Knechtel, Richards, and Rathbun)as Knemiceras bassleri was available to thewriter. It agrees in every respect with Lis-son's illustration of the holotype of K. gabbi,more so than any of the specimens describedhere.OCCURRENCE: Knemiceras gabbi is found

in the lower middle Albian Chulec formation,in bed 52 of the Sunchubamba section(A.M.N.H. No. 27852), associated with K.attenuatum, and in the middle Albian Crisne-jas formation, in bed 4 of the Celendin sec-tion (A.M.N.H. No. 27852/1).

Knemiceras triangulare, new speciesPlate 47, figures 1-2

A single specimen is available for study. Itis an entirely septate, poorly preserved,fragmentary steinkern.

MEASMEMENTS

A.M.NJH. No.27853

D H D/H T D/T U D/U97 55 .57 44 .41 15 .15

DESCRIPTION: The conch is discoidal, stout,very narrowly umbilicated. The whorl sec-

tion (fig. 36) is trapezoid. The greatest whorlthickness is just above the umbilical shoulderand is about three-fourths of the whorl

1956 4SI


height. If the tubercles are considered, thewhorl thickness is about the same as thewhorl height. The sides are slightly convexand strongly converge towards the broadlytruncated, flat venter. There are three rows oftubercles; just above the umbilical shoulderof the outer half whorl there are three strong,rounded tubercles. At about the middle of

A

BFIG. 36. Knemniceras triangutare, new species.

Suture line (A) and conch section (B) of theholotype; X1.

the sides, there is a second row of eight, veryfaint tubercles, slightly elongated radially.Finally, at the ventrolateral shoulder there isa third row of strong, spirally elongatedtubercles. Very weak, broad, fold-like falci-form extensions connect the three rows oftubercles; they are specially conspicuous inthe outer third of the sides. The suture (fig.36) is like that of most species of Knemiceras,with massive saddles which have a mediannotch and entire margins.

REMARKS: Knemiweras trsangulare resem-bles K. gabbi but is distinguished by its lesscompressed whorl section, more inflated sides,less prominent ribs, and by the presence of arow of weak mediolateral tubercles.

OCCURRENCE: KEnemiceras triangulare wascollected from the Chulec formation, in bed 8of the Sihuas section (A.N.M.H. No. 27853),together with Douvilleiceras monile, Paren-gonoceras peruvinum, Brancoceras aegocera-toides, K. raimondii, and K. attenuatum.

Knemiceras ovale, new speciesPlate 52, figures 1, 4

Knemiceras attexuatum-gabbi SOMMERMEIER,1910, p. 341, pl. 9, fig. 1.Only two poorly preserved steinkerns are

available for study. The holotype, A.M.N.H.No. 27854, is a half-disc 140 mm. in diameterwhich includes part of the body chamber.Specimen A.M.N.H. No. 27854/1, anotherhalf-disc 120 mm. in diameter, includes also asmall part of the body chamber.

DESCRIPTION: The conch is discoidal,stout, narrowly umbilicated. The whorl sec-tion (fig. 37) is compressed, ovoid, truncated,with indistinct umbilical wall and roundedumbilical shoulder. The greatest whorl thick-ness is at the end of the first third and isabout two-thirds of the whorl height. Thesides are bulging, with maximum convexity

FIG. 37. Knemiceras ovale, new species. Conchsection of the holotype; XI.

in the inner third, and converge towards theflat and broadly truncated venter. There arethree rows of tubercles. One row of pointedtubercles (three in a half whorl) is at theend of the inner third of the sides; the secondrow of rounded, weak tubercles (eight in ahalf whorl) is at about the middle of theouter third; finally, there is a third row ofstrong, spirally elongated tubercles at the

452 VOL. 108

I


ventrolateral shoulder. The suture has quad-rate saddles with a median notch and slightlydenticulated margins.REMARKS: Knemiceras ovale is distin-

guished from K. gabbi, with which it wasconfused by Sommermeier, by its bulgingsides, ovoid whorl section, presence of a thirdrow of tubercles in the outer third, less prom-inent and less numerous umbilical tubercles,and by the lack of ribs. Knemiceras tri-angulare differs from K. ovale by its less com-pressed whorl section, less convex sides, andin that the second row of tubercles is at aboutthe middle of the sides, not in the outerthird as in the latter.OCCURRENCE: Knemiceras ovale is found

in the middle Albian Crisnejas formation, inbed 3 of the Uchupata section (A.M.N.H.No. 27854/1) associated with Lyellicerasulrichi, and in bed 20 of the Celendin section(A.M.N.H. No. 27854) associated with L.pseudolyelli.

?Knenmiceras ollonense (Gabb)Plate 50, figure 5

A(mmonites) ollonensis GABB, 1877, p. 271,pl. 38, figs. 4-4a.A single specimen (A.M.N.H. No. 27855)

is tentatively assigned to this poorly knownspecies. It is a complete disc with the shellpreserved in a few places. The outer halfwhorl belongs to the body chamber.

MEASUMzNTSA.M.N.H. No.

27855D H D/H T D/T U D/U114 61 .53 39 .34 16 .14

DESCRIPTION: The conch is discoidal, flat,narrowly umbilicated. The whorl section(fig. 38) is compressed, subtrapezoidal, withsteep umbilical wall and broadly rounded um-bilical shoulder. The sides are subflattenedand converge towards the flat, truncatedventer. The greatest thickness is in theinner third and is less than two-thirds of thewhorl height. Just above the umbilicalshoulder of the outer volution is a row ofeight pointed tubercles which are elongatedin a prorsiradiate direction. Very faint,broad, fold-like prorsiradiate ribs start inthese tubercles, and others are intercalatedabout the middle of the sides. All the ribs

end in numerous, spirally elongated tuberclesat the ventrolateral shoulders. The ribs areobliterated in the body chamber. The shellis marked by strong sigmoidal growth striae.The suture is like that of K. attenuatum.

FIG. 38. ?Knemiceras ollonense (Gabb). Conchsection of specimen A.M.N.H. No. 27855; X 1.

REMARKS: Hyatt (in Gabb, 1877, p. 272)considered the holotype of K. ollonense as anintermediate form between K. attenuatumand K. gabbi. It has the whorl section of K.attenuatum but is distinguished by its largersize and the lack of a row of mediolateraltubercles. From K. gabbi it is distinguishedby its more compressed whorl section and itssubdued ornamentation.OCCURRENCE: ?Knemiceras ollonense is

found in the lower Albian Inca formation, inbed 50 of the Sunchubamba section(A.M.N.H. No. 27855) together with Para-hoplites nicholsoni and Desmoceras chimuense.It is very remarkable because it is the onlyspecies of Knemiceras found in the Inca for-mation; all the other species are known to beabundant in the overlying beds of the middleAlbian Chulec formation.

Knemiceras raimondii LissonPlate 48, figures 1-5

Knemiceras raimondii LIss6N, 1908, p. 4a, pl.4, figs. la-e, 2.

KRnemiceras attenuatum-crassinodosum SOM-MERMEIER, 1910, p. 345, text figs. 26-27, pl. 13,figs. 1-2.Knemiceras attenuatum-Raimondi, SOMMER-

MEIER, 1910, pp. 345, 346, p1. 13, figs. 3-7, p1.14, figs. 1-3.

Seventeen steinkerns, including severalcomplete discs, are assigned to this species.

4531956

BULLETIN AMERICAN MUSE

MEASUMENTS6D H D/E

56.5 30 .5359.5 32 .5465 33 .5175 39.5 .5376 37.5 .4998 49 .50112 58 .52112 55 .49117 64 .55

T D/T U D/U18 .32 7.5 .1317.5 .29 7 .1222 .30 10 .1527 .36 10.5 .1426 .35 11 .1435 .36 16 .1640 .36 18 .1639 .35 23 .2038 .32 14.5 .12

;UM OF NATURAL HISTORY VOL. 108

(between the radii of 10 and 15 mm.) fromvery high and compressed subtrapezoidal tocompressed rectangular; the greatest thick-ness moves, at the same time, from theumbilical shoulder to about the middle of thesides and is about two-thirds of the whorlheight. The sides are broadly convex tosubflattened, and are converging in theearly whorls but subparallel in the later ones.The umbilical shoulder is abruptly rounded

A

B

D EFIG. 39. Knemiceras raimondii Liss6n. A, B, C. Suturelines of specimens A.M.N.H. Nos. 27856:7, 27856:6, and

27856:2. D, E. Conch sections of specimens A.M.N.H. Nos.27856:7 and 27856:2. All XI.

DEscRIPTIoN: The conch is large, stout,discoidal, narrowly umbilicated. The whorlsection (fig. 39) changes in the early whorls

in the early whorls but tends to become morebroadly rounded. The venter is broad, flat,or even subconcave, becoming slightly

A.M.N.H.Nos.

27856:127856/1:127856:227856:327856:427856:527856:627856:727856/1:2

454


vaulted in the large specimens. There arethree distinct, very prominent rows of tuber-cules which start very early in the ontogeny.Before a radius of 20 mm., all three rows oftubercles are already present, and by aradius of 40 mm. (diameter of 70 mm.) thethree rows of tubercles have about the samestrength. The inner row is just above theumbilical shoulder, and has seven high tuber-cles, slightly elongated radially. For each ofthem, there are two or three pointed,elongated tubercles at about the middle ofthe sides and three or four spirally elongatedtubercles at the ventrolateral shoulders. Thetubercles vary in strength and unusuallybecome thorny, as in specimen A.M.N.H.No. 27856:4 (pl. 48, figs. 1-2). The ventro-lateral tubercles may be corresponding ornot. Strong, fold-like, falciform ribs connectthe three rows of tubercles; some of themfork at the mediolateral tubercles, others aresimply intercalated. In the large specimens,the ribs may even be marked on the venter,although in some specimens they are veryweak. Beyond a diameter of 100 mm., bothtubercles and ribs become weaker. The suture(fig. 39) has the basic Knemiceras pattern:large, massive, quadrate saddles which havea median notch and entire margins. The lobesare strangulated and digitated. The ventrallobe has two arms which may be directedadapically or extend laterally. The suture isvery plastic and is affected considerably bythe position of the tubercles.REMARKS: Knemiceras raimondii approach-

es K. attenuatum in ornamentation but is dis-tinguished by its rectangular whorl section,larger size, and the comparatively early ap-pearance of the ornamentation. Knemicerasovale and K. triangulare have different whorlsections than K. raimond*i and, moreover,the mediolateral row of tubercles in these twospecies is not so conspicuous as in the latterspecies.OCCURRENCE: Knemiceras raimondii is the

most common ammonite in the Chulec forma-tion (lower middle Albian). It occurs in beds58 and 70 of the Cajamarca section (A.M.N.IH.Nos. 27856/1 and 27856/2) associated withK. attenuatum, Douvilleiceras monile, and Pro-lyelliceras peruvianum; in bed 8 of the Sihuassection (A.M.N.H. No. 27856) together withK. triangulare, K. attenuatum, K. raimondii

tardum, Brancoceras aegoceratoides, P. peru-vianum, and D. monile; and in bed 23 of thePomachaca section (A.M.N.H. No. 27856/3).

Knemiceras raimondii pacfficum, newsubspecies

Plate 49, figure 1This subspecies is erected on the basis of a

single specimen (A.M.N.H. No. 27857), 130mm. in diameter, which has the shell pre-served. The measurements were taken at adiameter of 90 mm., for the specimen is some-what crushed adorally.

MEASUMMNTA.M.NS. No.

27857D H D/T T D/T U D/U90 45.5 .51 31 .34 16 .18

DESCRIPTION: The shape of the conch andof the whorl section is the same as in K.raimondii. It also has three prominent rowsof tubercles, but they are spinate and morenumerous than in K. raimondii. In the outervolution, the first row is just above theumbilical shoulder and has nine long, broken,spinate tubercles; the second row is at aboutthe middle of the sides and has 22 pointedtubercles which are more closely crowded be-tween the radii of 40 and 50 mm. The ventro-lateral shoulders are provided with morenumerous, spirally elongated tubercles.OCCURRENCE: This subspecies is found in

the lower Albian Crisnejas formation, inbed 4 of the Celendfn section, associated withK. gabbi.

Knemiceras raimondii tardum, new sub-species

Plate 48, figures 6-7This subspecies is based on a single,

thoroughly septate, well-preserved steinkern.MEASUhEXlSNT5

A.M.NJH. No.27858

D H D/H T D/T U D/U70 36 .51 20.5 .29 8 .11

DEsCRIPTION: Knemiceras raimondii tar-dum has the same whorl section, suture, andornamentation as K. raimondji (fig. 40). Itdiffers only because of a conspicuous onto-genetic retardation. The change of the whorlsection from high and compressed sub-trapezoidal to compressed subrectangulartakes place at a radius of 35 mm. Also, theappearance and the development of the

1956 455

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYornamentation are delayed. Whereas in K.raimondii the three rows of tubercles ap-pear before a radius of 20 mm., in K. rai-mondii tardum they make their appearanceat a radius of 35 mm.At a radius of 30 mm., the whorl section is

high, compressed, and subtrapezoidal, withthe greatest thickness near the umbilicus;the sides are subflattened and converge to-wards the narrow, flat, truncated venter; the

.~~~~~~~~~~~A

BFIG. 40. Knemiceras raimondii tardum, new

subspecies. Suture line (A) and conch section (B)of the holotype; XI.

ventrolateral shoulders are angular. Half a

whorl later, the whorl section is sub-quadrate, with the greatest thickness atabout the middle of the sides, which are

parallel between the two inner rows oftubercles and slightly converging between thetwo outer ones. Growth has been marked in

venter width. All the three rows of tuberclesapPear almost simultaneously at a radius of35 mm.; they have the same attitude andstrength as in K. raimondij.

OCCURRENCE: This subspecies occurs inthe lower middle Albian Chulec formation,in bed 8 of the Sihuas section, associated withDouvilleiceras monile, Prolyelliceras peruvian-um, and several other species of Knemiceras.

Knemiceras? ziczag BreistrofferPlate 52, figure 2

Knemiceras altenuatum Hyatt; DOUVILLi, 1906,p. 151, p1. 4, fig. 1.Knemiceras (?) ziczag BREISTROFFER, 1952, p.2634.

A single, very poorly preserved fragment ofan individual at least 150 mm. in diameter isconspecific with the specimen illustrated byDouville and designated by Breistroffer asthe holotype of Knemiceras (?) ziczag.DESCRIPTION: The whorl section is com-

pressed, ovoid, with the greatest thickness atabout the middle of the sides; it is about two-thirds of the whorl height. The sides are con-vex and make an even curve with therounded venter. The umbilical and the ven-trolateral shoulders are indistinct andbroadly rounded. In one-quarter of a volu-tion, on the middle of the sides, there are twovery large, elongated, high, round-crestedtubercles which are about half of the whorlheight in length; their upper end is broken.At the ventrolateral shoulder there are fiveblunt tubercles, and although the venter isweathered, it is possible to see the "bourreletsen ziczag" shown by the holotype.The suture has massive, large, quadratesaddles which have a median notch and

denticulated margins.REMARKS: Knemiceras? ziczag deviates from

all the other species of K-nemiceras by its ovoidwhorl section, the lack of a truncated venter,the peculiar ornamentation, and the indenta-tion of the saddle margins. The large lateraltubercles resemble the ribs of some species ofDipoloceras. Until better material can begathered, the generic determination will re-main doubtful.OCCURRENCE: This species is found in the

Crisnejas formation, in bed 2 of the Uchupatasection (A.M.N.H. No. 27859) together withKnerniceras gabbi, K. syriacum, and Paren-gonoceras pernodosum.

456 VOL. 108


SUPERFAMILY DIPOLOCERATACEAE SPATH,1921

FAMILY DIPOLOCERATIDAE SPATH, 1921OXYTROPIDOCERAS STIELER, 1920

Oxytropidoceras carbonarium (Gabb)Plate 49, figure 6

Ammonites carbonarius GABB, 1877, p. 269,pl. 38, fig. 2.

Schloenbachia acutocarinata (Shumard) Marcouvar. multifida STEINMANN, 1881, p. 139, pl. 7,fig. 1.

Amrn. carbonarius Gabb; STEINMANN, 1882, p.167.

Schloenbachia (Mortoniceras) Royssiana d'Orb.var. multifida Steinmann; SCHLAGINTWEIT, 1912,p. 64.

Schloenbachia multifida Steinmann; DOUGLAS,1921, p. 267, pl. 14, fig. 25.

Oxytropidoceras (Manuaniceras?) carbonariumGabb; REESIDE, 1927, in Wasson and Sinclair, p.1271, pl. 12, figs. 18-20.

Oxytropidoceras cf. acutocarinatum (Shumard);A1DKINS, 1928, p. 226, pl. 5, fig. 1.

Oxytropidoceras (Schloenbachia) peruvianum v.Buch var. multifida STEINMANN, 1930, p. 136,fig. 156.

Oxytropidoceras cf. multifidum (Steinmann);SPATH, 1930, p. 61, P1. 71.

Oxytropidoceras acutocarinatum Shumard var.mulifida Steinmann; COLLIGNON, 1936, inBesairie, p. 181, pl. 20, fig. 1.

Oxytropidoceras (Manuaniceras) carbonarium(Gabb); KNECHTEL, 1947, in Knechtel, Richards,and Rathbun, p. 107, pl. 27, fig. 4, pl. 28, fig. 2,pl. 29.

DESCRIPTION: The conch is large, lentic-ular, very narrowly umbilicated. The whorlsection is a strongly compressed ogive, withflattened sides which in the outer fourthbecome convex, converge, and form a fastigateventer provided with a high carina. Numer-ous uniform, closely spaced ribs begin at theumbilical shoulder; they are straight andprorsiradiate to the end of the third fourthwhere they bend and strongly project for-ward; they vanish before reaching the carina.Most, if not all, of the ribs dichotomize be-fore reaching the inner fourth of the sides.They are flat-topped and reach their max-mum width at the end of the second thirdwhere they are four or five times wider thanthe almost linear grooves that separate them.On the steinkern, the ribs offer quite a differ-ent view, for they are less flattened than in

the shell and are as wide as the rounded anddeep interspaces. The illustrated fragmentshows remarkably well the dichotomy of theribs and the differences of ribbing in theshell and in the steinkern.

REMAR:KS: Oxytropidoceras carbonarium wasoriginally described by Gabb (1877) on thebasis of specimens from Pariatambo, cen-tral Peru; in his description, he does not men-tion the forking of the ribs, but his illustra-tion shows it well. Steinmann (1881), un-aware of Gabb's publication and working onmaterials from the same locality, describedhis Schloenbachia acutocarinata Shumard(Marcou) var. multifida. One year later,however, Steinmann (1882, p. 167) reviewedGabb's work and recognized the conspecific-ity of Amm. carbonarius Gabb and hismultifida. He said: "Amm.rn carbonariusGabb ... ist dieselbe charakteristische Art,welche ich als Schloenbachia acuto-carinataShum. sp. bezeichnet und abgebildet habe.Die Zeichnung Gabb's k6nnte fast nachmeinem Stulcke angefertig sein.... " Thisbinding statement was unfortunately over-looked by most of the later workers.

Reeside (1927, in Wasson and Sinclair)and Knechtel (1947, in Knechtel, Richards,and Rathbun) have correctly interpretedArnm. carbonarium and have assigned it tothe subgenus Manuaniceras. However, Spath,the author of this subgenus, has always re-ferred to 0. multifidum (= 0. carbonariurn) asbelonging to Oxytropidoceras, sensu stricto,although recognizing at the same time thatit is the closest relative of Manuanicerasmanuanense, genotype of Manuaniceras.

Oxytropidoceras acutocarinatum (Shumard)is an ill-defined and doubtful (Adkins, 1928,p. 224; Spath, 1934, p. 19) species which,according to the interpretations of Steinmannand other authors, differs from 0. carbonari-um mainly by the lack of the remarkabledichotomy of the ribs which characterizes 0.carbonariunm. Oxytropidoceras parinensis Ols-son, a slightly more umbilicated form, is veryclosely related to, if not the same as, 0.carbonarium.OCCURRENCE: Oxytropidoceras carbonarium

is the most common ammonite in the me-

dial Albian Pariatambo formation. Usually,it occurs in limestone concretions from whichentire specimens are difficult to obtain. It also

1956 457


occurs in the upper part of the middle AlbianCrisnejas formation. Specimen A.M.N.H.No. 27860 was found in bed 14 of the Paria-huanca section together with 0. douglasi, Ly-elliceras lyelli, L. ulrichi, Brancoceras aegocer-atoides, and Desmoceras lktidorsatum.

Oxytropidoceras peruvianum (von Buch)Plate 49, figure 5

Ammonikes peruvianus vox BucH, 1839, p. 5,pi. 1, fig. 5.

Schloenbachia sp. (cf. acutocarinaka BMse nonShumard); DOUGLAS, 1921, p. 269, pl. 16, fig. 1.

Oxytropidoceras n. sp. (aff. supani Lasswitz)ADKINS, 1928, p. 226, pl. 5, fig. 2.Steinmann (1881, p. 140) referred to the

holotype of Oxytropidoceras peruvianum as"ein Ammonit mit schmalen Rippen undbreiteren Zwischenriumen." Later Schlagin-tweit (1912, p. 71) described the same speci-men in the following terms: "Es sind Steinern-stticke mit ungegabelten, schmalen Rippen,die gegen die Externseite nur langsam an-schwellen und nur schwach S-farmig gebogensind. Jedoch sind die Rippen etwas abge-wittert und die Externseite ist nicht intakt;die Rippen miissen in ihrem oberen nicht meirerhaltenen Teil starker angeschwollen undkrrftiger gebogen gewessen sein. Dass die Rip-pen erheblich schmaler seien wie die Zwisch-enraume, trifft nur fuir die untere (gegen denNabel zu) HIalfte der Schmale zu."Specimen A.M.N.H. No. 27861 (pl. 49,

fig. 5), a steinkern with patches of shell,agrees with these descriptions as well aswith von Buch's illustration of the holotype.

DESCRIPTION: The conch is large, lentic-ular, narrowly umbilicated. The whorl sec-tion (fig. 41) is a high and compressed ogive.The sides are gently convex, with maximumconvexity in the inner third, and convergetowards the fastigate venter which is pro-vided with a high carina. Fine, sigmoidalribs begin at the umbilical shoulder; theyare prorsiradiate and subangular to the endof the first fourth where they become lessprorsiradiate, much broader, and slightlyflat-topped; their adoral edge is steeper thanthe adapical one. By the end of the thirdfourth, the ribs become again more prorsi-radiate and project forward, although not sostrongly as in 0. carbonarium. The ribs have

about the same shape both in the shell and inthe steinkern.REMARKS: There is considerable confusion

in the literature regarding this species and itsrelationships with others of the same genus.Spath (1934, p. 20) has said: "Judging by thefigure (v. Buch, 1839, pl. 1, fig. 5) Amm.peruvianus is more like 0. acutocarinata, i.e.,

FIG. 41. Oxytropidoceras Peruvianum (von Buch).Conch section of specimen A.M.N.H. No. 27861;XI.

it is what Marcou considered to be Amm.peruvianus.... It is, of course, often foundthat the ribbing varies greatly in these formswith the mode of preservation, and since Ihad the opportunity of examining manyspecimens from Texas ... I am prepared toaccept forms like 0. carbonarium (Gabb),0. multifida (Steinmann) and 0. supani(Lasswitz) all taken previously as distinctspecies to be mere varieties of 0. acuto-carinata. Since Prof. Adkins is somewhatdoubtful and since I have already mentionedthat there is a possibility of its being the sameas v. Buch Amm. peruvianum, the continueduse of Oxy. carinatum may be opened tocriticism." The present writer believes that 0.carbonarium, 0. Peruvianum, and 0. acuto-

458 VOL. 108


carinatum are three different forms. Oxytro-pidoceras carbonarium and 0. acutocarinatum,as stated by Steinmann, are flattened formswith very closely spaced, flat-topped ribswhich are strongly projected forward in theouter third and which differ from each otheronly by the remarkable dichotomy of theribs of 0. carbonarium. Oxytropidocerasperuvianum has a proportionally thickerwhorl section, and its ribs are not so closelyspaced nor so conspicuously flat-topped asthose of the other two forms. Whether 0.peruvianum and 0. roissyanus are the same,as held by Schlagintweit (1912, p. 64), thepresent writer is in no position to state. Itseems, however, that 0. roissyanus has ribswhich are stronger and more distinctlysigmoidal and projected forward than thoseof 0. peruvianum.OCCURRENCE: The holotype was collected

by von Humboldt in 1802 in Montin, nearthe Lajas section, presumably from thePariatambo formation where it is veryabundant. Specimen A.M.N.H. No. 27861is from the upper middle Albian Pariatamboformation, in bed 26 of the Pomachaca sec-tion.

Oytropidoceras douglasi KnechtelOxytropidoceras douglasi KNECHTEL, 1947, in

Knechtel, Richards, and Rathbun, p. 106, cumsynon., pl. 24, figs. 1-4, pl. 25, figs. 1-2, pl. 26, pl.27, figs. 2-3, pl. 28, fig. 1.

Four fragments (A.M.N.H. No. 27862) arereferred to this species. The type material,described by Knechtel, was available to thepresent writer for study.

DESCRIPTION: The conch is large, lentic-ular, narrowly umbilicated. The whorl sec-tion (fig. 42) is biconvex, inflated, with highand perpendicular umbilical wall and abruptumbilical shoulder. The greatest thickness isat the end of the inner third and is betweentwo-thirds and three-fourths of the whorlheight. The venter is fastigate and providedwith a high and solid carina. Single, sigmoi-dal, prorsiradiate ribs begin just above theumbilical shoulder; they are subacutelycrested up to the end of the inner third wherethey become increasingly more rounded andbulged, their adoral slope being steeper thanthe adapical one.

REMARKS: Oxytropidoceras belknapi, geno-

type of the subgenus Adkinsites, is similar inwhorl section and in the shape of the ribs to0. douglasi. It is distinguished by the pres-ence of forked and intercalated ribs.OCCURRENCE: Oxytropidoceras douglasi is

found in the middle Albian Crisnejas forma-tion, in bed 2 of the Santo Cristo Bridge sec-

FiG. 42. Oxytropidoceras douglasi Knechtel.Conch section of specimen A.M.N.H. No. 27862;xi.

tion (A.M.N.H. No. 27862), in the middleAlbian Pariatambo formation, in bed 14 ofthe Pariahuanca section, and in the lowestbeds of the Albian-Turonian Jumasha forma-tion, in bed 4 of the Uchupata section.

ViENZOLICERAS SPATE, 1920

Venezoliceras venezolanum (Stieler)Plate 53, figure 5

Schloenbachia (Mortoniceras) inflata Sowerby;SCHLAGINTWEIT, 1912, p. 79, text figs. 1-2.

Oxytropidoceras venexolanum STIELER, 1920, p.394.

Venezoliceras venezokense (Stieler); SPATEa, 1925,p. 182.The record on this genotype species is

limited to a poor illustration of the whorlsection of the holotype, and to the inadequatedescriptions by Schlagintweit and Stieler.Two flattened specimens are referred to

this species; they offer only one side to view.

1956 459


M2IASUREMENTSA.M.N. Nos. D H D/H T D/T U D/U

27863 38.5 20 .52 - 7.5 .1927863/1 100 48 .48 - 20 .20

DEscRIPTION: The conch is lenticular, nar-rowly umbilicated. According to Schlagin-tweit's illustration, the whorl section is a highand compressed ogive with biconvex sideswhich converge towards the fastigate venterprovided with a high carina. The availablespecimens show that the carina is about one-fifth of the whorl height. There are 17 to 21straight, single, prorsiradiate ribs whichstart at the umbilical shoulder and are nar-rower than the rounded interspaces. The ribsare provided with two rows of tubercles: onerow of pointed tubercles at the middle of thesides which appear at a radius of 15 mm. anda second row of more prominent, spirallyelongated tubercles at the ventral end of theribs. Both rows of tubercles are alreadypresent at a radius of 15 mm.REMARKS: Venezoliceras guaduasense (d'Or-

bigny), another poorly known species, hassimilar whorl section and ornamentation; it isdistinguished because its mediolateral tuber-cles are present only every two or three ribsand because, apparently, the ventrolateralshoulder is well marked.

OCCURRuENCE: Venezoliceras venezolanum isfound in the middle Albian Pariatamboformation, in bed 85 of the Cajamarca section(A.M.N.H. No. 27863), associated withOxytropidoceras carbonarium and 0. douglasi,and in bed 26 of the Pomachaca section(A.M.N.H. No. 27863/1), associated with 0.

peruvianum. Schlagintweit's specimen, holo-type of the species, is reported to be from thePariatambo formation, from Huallanca.

Venezoliceras harrisoni,l new species

Plate 53, figure 6This species is based on a single, fragmen-

tary, flattened specimen (A.M.N.H. No.27864) which has only one side visible. Itmust have been at least 150 mm. in diameter.DEscpIPuoN: The conch is large, discoidal,

fairly narrowly umbilicated. The whorl sec-

tion is apparently a very high and compressed

I Named after Dr. J. V. Harrison, whose carefulobsrvations have contributed much to the under-

standingof the gelogy of Peru.

ogive with low and perpendicular umbilicalwall. The sides are flattened up to the end ofthe second third, where they become convexand converge towards the fastigate venterwhich is provided with a very high carina.The outer volution has 62 slightly sigmoidal,strongly prorsiradiate ribs, about half ofwhich start at the umbilical shoulder. Theothers are either intercalated or forking ribswhich in the early part of the outer whorlappear at about the middle of the sides, butwhich tend to appear closer to the umbilicus.Adorally, there are no forking ribs, and theintercalated ones start in the inner third andhave almost the same length as the primaryones. The ribs are provided with two rows oftubercles: one row of prominent, pointed,radially elongated tubercles at about themiddle of the sides which are present only inthe primary ribs, and which appear at a diam-eter of 70 mm.; the second row is composedof spirally elongated tubercles at the ventralend of every rib. The ribs are subanguIar inthe inner half of the sides but become roundedin the outer one.REMARKS: Venezoliceras venezolanum is

similar in whorl section, carina, and patternof ornamentation to V. harrisoni. It is dis-tinguished by the lack of forking ribs, thesmaller number of ribs per volution, the lessconspicuous development of the mediolateraltubercles, and the straightness of the ribs.Venezoliceras guaduasense is distinguishablefrom V. harrisoni by the lack of secondaryribs and by the early appearance of thetuberculation.OCCURRENCE: Specimen A.M.N.H. No.

27864 was collected from the Pariatamboformation, in bed 85 of the Cajamarca sec-tion, together with V. venezolanum and Oxy-tropidoceras carbonarium.

DIPOLOCERAS HYATT, 1900Dipoloceras sp. indet.

Plate 50, figure 6?Mortoniceras rostratum Sowerby; DOUVILLE,

1906, p. 149, pl. 4, fig. 4.A large body chamber, 260 mm. in length,

part of an individual of more than 220 mm.i.n diameter, belongs to this genus. It is inade-quate for specific determination.DESCRIPTION: The conch is large and

460 VOL. 108


evolute. The intercostal whorl section (fig. 43)is slightly compressed, subquadrate, withsteep umbilical wall and abruptly roundedumbilical shoulder. The sides are convex andslightly converging; the ventrolateral shoul-ders are very broadly rounded, and theventer is broad and provided with a low but

FIG. 43. Dipoloceras sp. indet. Conch sectionof specimen A.M.N.H. No. 27865; X 1.

distinct carina. The costal whorl section isquadrate.

In one-quarter of a volution, there areseven strong, straight ribs which start at theumbilical shoulder and end near the carina.They are subrounded, with broader androunded interspaces, and are higher at theventrolateral shoulders than at the middle ofthe sides; also, at the ventrolateral shouldersevery rib swells into a large tubercle whichextends almost to the carina.REMARKS: Dipoloceras frederickburgense

Scott has a similar whorl section but is morefinely ribbed than Dipoloceras sp. indet.OCCURRENCE: Specimen A.M.N.H. No.

27865 was found in the upper middle AlbianPariatambo formation, in bed 86 of theCajamarca section.

BRANCOCERAS STEINmAN, 1881Brancoceras aegoceratoides Steinmann

Plate 49, figures 2-4Brancoceras aegoceratoides STEINMANN, 1881,

p. 137, pl. 7, figs. 2-2b.Braszcoceras varicosum Sow.; SCHLAGINTWEIT,

1912, p. 85.Brancoceras aegoceratoides Steinmann; KNECH-

TEL, 1947, in Knechtel, Richards, and Rathbun,p. 103, pl. 21, figs. 4a-c.

Brancoceras quenstedti KNECHTEL, 1947, in

Knechtel, Richards, and Rathbun, p. 103, pl.21, figs. Sa-b.

Eubrancoceras aegoceratoides (Steinmnann);BREISTROFFER, 1951, p. 266.

Five fragmentary specimens are assignedto this species.

EAS&RExNTS

A.MNoH. D H D/H T D/T U D/U27866:1 37 13.5 .37 12 .32 12.5 .3427866/1 29.5 11 .37 9.5 .33 11 .38

DESCRIPTION: The conch is small, dis-coidal, fairly widely umbilicated. The whorlsection is compressed, oval, with indistinctumbilical wall and very broadly roundedumbilical shoulder. The sides are flattenedand subparallel; the ventrolateral shoulder isalso broadly rounded and makes an evencurve with the semicircular venter. SpecimenA.M.N.H. No. 27866:1 has in the outer halfwhorl 16 strong, single, prominent ribs whichstart at the umbilical shoulder; they arestraight, prorsiradiate, rounded, and broaderthan the interspaces to the ventrolateralshoulders where they are slightly moreprorsiradiate and broader. On the venter, theribs are very conspicuous, rounded, and withwider interspaces. The first ribs appear at aradius of 4 to 5 mm. They are irregular, somefork out of a point in the umbilical shoulder,and all flatten out at the ventrolateral shoul-ders. These early ribs are sharp-edged andwidely spaced. At a radius of 9 to 10 mm.,they cross over the venter. The suture (fig.44) is simple, with broad and massive lateral

f

FIG. 44. Brancoceras aegocera4oides Steinmann.Suture line of specimen A.M.N.H. No. 27866:2;x1.

saddles which have denticulated margins,and a first lateral lobe which is trifid anddeeper than the ventral one.REMARKS: Brancoceras aegoceratoides dif-

fers from other species of the genus, such asB. senequieri and B. cricki, by the lack of acarina at any stage.OCCURRENCE: Brancoceras aegoceratoides is

a common ammonite in the middle AlbianPariatambo formation where it is associated

1956 461

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYwith several species of Oxytropidoceras, Vene-zoliceras, Lyelliceras, Dipoloceras, and Desmo-ceras. It is also rarely found in the lowermiddle Albian Chulec formation, associatedwith species of Knemiceras, Douvilleiceras,Protanisoceras, and Prolyelliceras.

SUPERFAMILY ACANTHOCERATACEAEHYATT, 1900

FAmILY LYELLICERATIDAE SPATH, 1921PROLYELLICERAS SPATH, 1930

Prolyelliceras peruvianum SpathPlate 50, figures 1-4

Acanthoceras Lyelli Leym.; STEINMANN, 1881,p. 135, pl. 7, figs. 3-3a.

Aca-nthoceras prorsocurvatum Gerhardt; Dou-VILLi, 1906, p. 144, p1. 2, figs. 1-la.

Prionotropis Radenaci Pervinquie're; SOMMER-MEIER, 1910, p. 381, text fig. 37, pl. 14.

ProlyelZiceras peruvianum SPATH, 1930, p. 65(footnote).

Prolyelliceras ? lobatum RIEDEL, 1937-1938, p.57, pl. 9, figs. 9-11, pl. 14, figs. 28-29.

Eight fragmentary steinkerns, includingtwo half-discs, are assigned to this species.The largest specimen (A.M.N.H. No. 27867;pl. 50, figs. 1-2) is for the most part a frag-ment of body chamber belonging to an in-dividual more than 100 mm. in diameter.

A.MNMH. Nos.27867:227867/1:1

MEASURENTSD H D/H T

49.5 18.5 .37 16.543 17 .39 14.5

D/T U D/U.33 17 .34.34 15 .34

DESCRIPTION: The conch is discoidal,fairly widely umbilicated. The whorl section(fig. 45) is compressed, oval to subquadrate,with the greatest thickness at about the mid-dle of the sides. The umbilical wall is indis-tinct, and the umbilical shoulder is broadlyrounded. The sides are convex and subparal-lel. The ventrolateral shoulder is broadlyrounded in the early whorls but becomes welldefined at about a radius of 40 mm., giving a

subquadrate appearance to the whorl section.In the body chamber, they become againbroadly rounded, and the whorl section tendsto take the shape of a very inflated ogive.The venter is broad and makes an even curve

with the sides; in the body chamber it tendsto become fastigate. There are 15 to 17 single,strong ribs per half whorl; they appear at

about a radius of 10 mm. Between the radii

of 20 and 40 mm., the ribs are strong, sub-angular, fairly straight, prorsiradiate, andwith much wider and rounded interspaces; onthe venter, they are broader and. round-crested. On the body chamber, the. ribs havea tendency to become more rounded, sig-moidal, and to form an angle at the siphonalline. The ribs are provided with a row oftubercles at the siphonal line and another onealong the ventrolateral shoulder. The tuber-cles of these rows are spirally elongated andstrong to a radius of 30 mm. where they be-come pointed and subdued. On the bodychamber they are obliterated. The suture

A

BFIG. 45. Prolyelliceras peruvianum Spath.Suture line (A) and conch section (B) of specimenA.M.N.H. No. 27866:3; XI.

(fig. 45) is simple, with massive, broad, bifidsaddles and a trifid first lateral lobe which isequal in depth to the ventral lobe.REMARKS: Prolyelliceras peruvianum re-

sembles P. gevreyi Jacob in whorl section andpattern of ornamentation. In the latter spe-cies, however, the ribs seem to be interruptedacross the venter, and the siphonal tuberclesdo not correspond with the ventrolateral ones.Prolyelliceras peruvianum resembles also P.cotteri Spath, a poorly known species, in shapeand in the presence of three rows of tubercles.They are distinguishable because P. cotterihas intercalated and forked ribs and is moreclosely costate.The specimen described as Proyelliceras?lobatum by Riedel (1947-1948) belongs to

1'. Peruvianum. Riedel was misled by thelarge size of his specimen and hampered bythe poor knowledge of the Peruvian species.

462 VJOL. 108


OCCURRENCE: Prolyelliceras persvianum isa common ammonite in the lower middleAlbian Chulec formation, in bed 58 of theCajamarca section (A.M.N.H. No. 27867/1),associated with KJemiceras attenuatum, K.raimondii, and Douvilieiceras montile, and inbed 8 of the Sihuas section, where it is asso-ciated with several species of Kneimiceras, D.nonile, and Brancoceras aegoceratoides.

LYELLICERAS SPATE, 1921

LyelIiceras lyelli (Leymerie) D'ORBIGNYPlate 51, figures 1-3

Lyelliceras Iyelli (Leymerie MS) d'Orbigny;SPATH, 1923-1943, vol. 2, p. 316, cum synon., pl.32, figs. 9a-b, 12a-b, 13a-b.This well-known and world-wide species is

represented by seven well-preserved discsand several whorl fragments.

A.M.N.E.Nos.

27868:127868:227868:327868:427868:527868:627868:7

M1EAS=tENTS

D E D/H T D/T U U/E55424133.522.51818

21.515.51511.5987

.39

.36

.39

.34

.40

.44

.39

20.5151511107.57

.37

.36

.37

.34

.44

.41

.39

40.516.516148.566.5

.37

.39

.39

.33

.38

.33

.36

DESCRIPTION: The conch is discoidal,fairly widely umbilicated. The intercostalwhorl section is subcircular to subquadrate.The costal whorl section is polygonal. Theumbilical wall is low and has a broadly roun-ded shoulder. The sides are convex, and theventrolateral shoulders are broadly rounded,making an even curve with the arched venter.There are 20 to 22 single strong ribs per

whorl, which appear at about a radius of5 mm.; they are prorsiradiate up to the endof the inner third where they become radialand cross the venter uninterrupted. The ribsare provided with one row of pointed tuber-cles just above the end of the inner third ofthe sides; a second row of pointed tubercles,tending to become spirally elongated, atabout the end of the middle third of the sides;and a third row of more prominent, spirallyelongated tubercles at the ventrolateralshoulder; these ventrolateral tubercles arethe first to appear. Along the siphonal linethe ribs are provided with a row of tubercleswhich correspond and are similar in shape

and size to the ventrolateral ones. All thetubercles are present already at about a ra-dius of 9 to 10 mm. On the body chamber theribs tend to become sharp and the tubercula-tion to disappear.OCCURRENCE: LyeWliceras lyelli is a com-

mon species in the middle Albian Paria-tambo formation (bed 14 of the Pariahuancasection, A.M.N.H. No. 27868; bed 26 of thePomachaca section, A.M.N.H. No. 27868/1),where it is associated with Oxytiopidocerascarbonariumn, 0. peruvi&num, 0. douglasi,Braincoceras aegoceratoides, L. ulrichi, Vene-zoliceras venezolanwum, and V. harrisoni. It isalso rarely found in the lower middle AlbianChulec formation (in bed 10 of the Lajas sec-tion, A.M.N.H. No. 2 7868/2) associated withKnemiceras raimondii, K. attenuatum, Douvil-leiceras monile, Protanisoceras blancheti, Pro-lyelliceras peruviamnum, and, unusually, B.aegoceratoides. In England, L. iyelli seems tobe confined to the benattianus zone (Spath,1930, p. 1).Lyelliceras pseudolyelli Parona and Bonarelli

Plate 52, figure 3Acanthoceras pseudolyelli PARONA AND BONAR-

ELLI, 1896, P. 99, p1. 14, figs. la-c, 2a-b.Lyelliceras pseudolyelii (Parona and Bonarelli);

SPATE, 1923-1943, vol. 2, p. 319, cum synonz., pl.32, figs. 14a-b.

Lyelliceros pseudolyelli Parona and Bonarelli;RIEDEL, 193 7-1938, p. 54, p1. 9, figs. 5-6, p1. 13,fig. 16.

Nine specimens, most of them poorly pre-served steinkerns, are available for study.

A.M.N.H.Nos.

27869:127869:2

MEAStR33MNTS

D H D/E T D/T U D/U64 25.5 .40 22 .34 21 .3353 21.5 .4 - - 18 .34

DESCRIPTION: The conch is discoidal,fairly widely umbilicated. The whorl sectionis slightly compressed, subquadrate, withsteep umbilical wall and broadly roundedumbilical shoulder. The sides are convex andalmost parallel; the ventrolateral shoulder isrounded, and the venter is gently vaulted.There are 20 to 22 single ribs in the outerwhorl; they are prorsiradiate in the innerthird and radial in the outer two-thirds; onthe venter, they are very faint or altogethermissing. The ribs are provided at the end of

1956 463


the inner third with one row of pointed tuber-cles, which appear at a radius of 30 mm.; asecond row, at the end of the second third, ofmore prominent tubercles, which appearearlier than those of the first row and whichtend to become spirally elongated; and athird row of much larger and higher, spirallyelongated tubercles at the ventrolateral shoul-der. Along the siphonal line, there is a seventhrow of spirally elongated tubercles which donot correspond to, and are more numerousand smaller than, the ventrolateral tubercles.The suture (fig. 46) is similar to that of L.lyelli.A distorted specimen (A.M.N.H. No.

27869:3), about 100 mm. in diameter, shows

4_

FIG. 46. Lyelliceras pseudolyelli Parona andBonarelli. Suture line of specimen A.M.N.H.No. 27869:2; XI.

the body chamber where the ribs becomeprominent on the venter and the siphonaltubercles correspond with the ventrolateralones, a stage similar to that of L. Iyelli.REMARKs: Lyelliceras pseudolyelli differs

from L. lyelli by the different arrangement ofthe siphonal tubercles and the interruptionof the ribs over the venter. The Peruvianspecimens of L. pseudolyelli appear to have amore compressed and quadrate whorl section,larger size, and stronger ornamentation thanthe European examples.OCCURRENCE: This species is found in the

middle Albian Crisnejas formation, in bed 20of the Celendin section.

Lyeliiceras ulrichi KnechtelPlate 51, figures 4-7

Acanthoceras lyelli Leym.; SOMMERMEIER, 1910,p. 375 (pro parte).

Acanthoceras lyelli Leym.; SCHLAGINTWEIT,1912, p. 87 (pro parte).

LyilQiceras cf. cotteri Spath; RIEDEL, 1937-1938,p. 56, pl. 9, figs. 1-2, pl. 3, fig. 18.

Lyelliceras ulricki KNECHTEL, 1947, in Knechtel,Richards, and Rathbun, p. 99, pl. 23, figs. la-b.

Se'venteen specimens, all steinkerns, in-

cluding four complete discs, are assigned tothis species. Knechtel's holotype was avail-able to the writer.

A.MNH. DNos.

27870:1 13.527870/1:1 23.527870/2:1 35.527870:2 4027870:3 73

Knechtel'sholotype 115

MEASUREMENTSH D/H T D/T U D/U69.5121424

.44

.40

.34

.35

.33

6910.51321

.44

.38

.30

.32

.28

3.5

14.51633

.26

.41

.40

.45

36.5 .32 28 .24 52 .45

DESCRIPTION: The conch is discoidal,platy, fairly widely umbilicated. The inter-costal whorl section (fig. 47) is slightly com-pressed, oval, with the greatest thickness atthe end of the inner third; it has a low andindistinct umbilical wall and a broadly round-ed umbilical shoulder. The sides are convexand subparallel. The ventrolateral shouldersare broadly rounded and make an even curvewith the rounded venter. The costal sectionis polygonal. There are between 25 and 30single, strong ribs per whorl. They start at theumbilical shoulder and are slightly prorsiradi-ate, acutely crested, and with much broaderinterspaces to the end of the middle third;

tA

BFIG. 47. Lyelliceras ulrichi Knechtel. Suture

line (A) and conch section (B) of specimenA.M.N.H. No. 27870:3; XI.

thence they become more rounded, broader,and slightly more prorsiradiate. On the ven-ter, the ribs are broadly rounded, somewhatattenuated, and have the same width as theinterspaces. The ribs are provided with onerow of pointed tubercles at about the end ofthe middle third of the sides, and a second

464 VOL. 108


row of high, spirally elongated, strongertubercles at the ventrolateral shoulder. Alongthe siphonal line, the ribs are provided with arow of tubercles which correspond, and aresimilar in size and shape, to the ventrolateralones.The ribs appear first at about a radius of

5 mm. (pl. 51, figs. 6-7) as irregular, unevenwrinkles, which begin at the umbilical shoul-der and flatten out at about the ventro-lateral one. By a radius of 9 mm., papillatetubercles appear at the ventrolateral ends ofthe ribs, and at the same time the corre-

FAMILY ACANTHOCERATMDAEDE GROSSOUVRE, 1894

SHA.PEPICBRAS HYATT, 1903Sharpeiceras occidentale, new species

Plate 54, figures 5-6

A single steinkern, slightly larger than ahalf-disc and including a small part of thebody chamber, is the basis of this new species.

MEASENTS

A.M.N.H. No.27871

D H D/H T D/T U D/U136 49 .36 37 .27 47 .35

TABLE 2OCCURRENCE OF Lyetliceras ulricki

_ ~~~~~~~~N. of.

A.M.N.H. Nos. Bed Section Formation NSeifSpecimens

27870 14 Pariahuanca Pariatambo 1027870/1 4 Uchupata Jumasha 527870/2 3 Uchupata Paiatambo 227870/3 85 Cajamarca Pariatambo 127870/4 21 Hualgayoc Pariatambo 1

sponding siphonal tubercles appear on thesmooth venter. Soon after, the siphonal andventrolateral tubercles become spirally elon-gated, the pointed tubercles appear at theend of the middle third, and the ribs cross theventer.The suture (fig. 47) is often asymmetrical.

It is very simple, with broad, massive, bifidsaddles and long bifid lobes.REMARKS: Lyelliceras ulrichi resembles L.

mathewsi in whorl section, ribbing, and tuber-culation. It is distinguishable by its closerribbing and by the fact that the lateral tuber-cle appears much earlier in the ontogenythan in L. mathewsi, where it appears at a

radius of 35 mm. Lyelliceras prorsocurvatum isanother closely related form which has flexu-ous ribs.OCCURRENCE: Lyelliceras ulrichi is a com-

mon ammonite in the Pariatambo formation,associated with L. lyelli and several species ofOxytropidoceras and Venezoliceras. It is alsofound in the upper part of the Crisnejas for-mation and in the lowest beds of the Jumashaformation.

DESCRIPTION: The conch is large, discoidal,platy, fairly widely umbilicated. The inter-costal whorl section is very compressed,subrectangular, with very low and indistinctumbilical wall and broadly rounded umbilicalshoulder. The sides are subflattened andslightly converging. The ventrolateral shoul-der is very broadly rounded. The availablespecimen has 13 single, strong, straight ribsin the outer half whorl. All the ribs start atthe umbilical shoulder and bear four rows oftubercles; one row of faint, radially elongatedtubercles just about the umbilical shoulder,a second row of more conspicuous, radiallyelongated tubercles just below the middle ofthe sides, and a pair of tubercles at theventrolateral shoulder, of which the inner one(dorsal or third from the umbilicus) is blunt,conical, whereas the outer one (fourth fromthe umbilicus) is blunt and spirally elon-gated. The four ventral tubercles are evenlyspaced, of the same size, and are connectedby broad and low ribs.The suture is typical of Sharpeiceras; it

has three saddles on the sides and a fourth

4651956

4BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY

saddle on the umbilical shoulder; the firstlateral saddle is broad, quadrate, deeplydivided by a trifid lobule, and has phylloidendings. The first lateral lobe is very deep,trifid, and frilled.REMARKS: Sharpeiceras occidentale, S. in-

dic-um Kossmat [1895 (1895-1898), p. 199],and S. schlueteri Hyatt (1903, p. 111) havethe same very compressed, subrectangularwhorl section and four rows of tubercles. TheAndean form is distinguishable from S. in-dicum by its smaller number of ribs, the lackof forking ribs, and the subdued appearanceof the umbilical tubercles. From S. schlueteri,it is distinguishable by the even and closespacing of the four ventral tubercles, whereasin the German form, the tubercles on bothsides of the siphonal line are widely spaced.The ribbing of S. occidentale approaches thatof S. florencae Spath (1925, p. 198), whichhas a quadrate whorl section, conspicuousmediolateral tubercles, and its four ventraltubercles are not so closely set as those of thePeruvian form.OCCURRENCE: The holotype was collected

from the Yumagual formation, in bed 111 ofthe Cajamarca section, together with Para-turrilites lewesiensis (Spath).

Sharpeiceras is a widespread but scarcegenus. Sharpeiceras laticlavium Sharpe, thegenotype, occurs rarely in the Varians zone ofthe English Cenomanian (Wright and Wright,1951, p. 25).

ACANTHOCERAS NEnuAy, 1875Acanthoceras chasca, new species

Plate 53, figures 1-4One fairly complete specimen (A.M.N.H.

No. 27872) and three whorl fragments ofspecimens which must have been about150 mm. in diameter are assigned to thisspecies.

MEASV!NT5A.M.Nx. No.

27872D H D/H T D/T U D/U61 29 .48 27 .44 16 .26

DESCRIPTION: The conch is discoidal,stout, fairly narrowly umbilicated, with thewhorls little embracing, almost tangen-tial. The intercostal whorl section (fig. 48)is slightly compressed, subrectangular, with

high and steep umbilical wall and distinctumbilical shoulder. The sides are subflattenedand subparallel; the ventrolateral shoulder isrounded and the venter is broad and gentlyarched. The costal whorl section is quadrate.In the outer whorl, the holotype (A.M.N.H.No. 27872) bears 15 strong, round-crested,widely spaced, prorsiradiate ribs, few ofwhich are intercalated, or at least less promin-ent, than the others. The primary ribs areprovided with one row of weak, radially elon-gated tubercles at about the middle of theinner third. All the ribs have at about theventrolateral shoulder a pair of strong tuber-cles, of which the inner one (second from the

FJG. 48. Acanthoceras chasca, new species.Conch section of the holotype; XI.

umbilicus), slightly below the umbilicalshoulder, is conical and pointed and theouter one (third from the umbilicus), at theventrolateral shoulder, is spirally elongated.Between the second and third rows of tuber-cles, the ribs are more prorsiradiate, broader,and lower than on the sides; they do notcross the venter. Along the siphonal line,there is a row of spirally elongated tubercleswhich correspond in number but are lessconspicuous and slightly set backward thanthe ventrolateral tubercles. They becomefaint and obliterate in later stages.Specimen A.M.N.H. No. 27872/1 (pl. 53,figs. 1-2) is a quarter of a whorl of a specimenof about 150 mm. in diameter. It has strong,widely spaced ribs; the umbilical tubercles

are blunt and faint; the ventrolateral tuber-cles are attenuated and the siphonal ones aremissing.REMARKS: Acanthoceras chasca in generalshape, whorl section, and ribbing is similar

to A. stephensoni Adkins (1928, p. 246),from which it can be distinguished by itssmaller umbilicus and less prominent ventro-lateral tubercles.

466 VOL. 108


OCCURRENCE: This species is a commonammonite in the upper Cenomanian Romironformation, in bed 48 of the Celendin section(A.M.N.H. No. 27872), associated with Neo-lobites kusmmeli, Lissoniceras mermeti, andForbesiceras sp. It is also found in bed 43 ofthe Polloc section (A.M.N.H. No. 27872/1)and in bed 127 of the Cajamarca section.

Acanthoceras pollocense,1 new speciesPlate 53, figures 10-11

Four whorl fragments are available forstudy. Specimen A.M.N.H. No. 27873:1(pl. 53, figs. 10-11) is designated the holo-type.

DESCRIPTION: The conch is discoidal,stout, fairly narrowly umbilicated, with verylittle embracing whorls. The whorl section(fig. 49) is depressed, with very high and per-

FIG. 49. A canthoceras pollocense, new species.Conch section of the holotype; X1.

pendicular umbilical wall and abruptlyrounded umbilical shoulder. The height of thewhorl is about four-fifths of the maximumthickness, which is near the umbilical shoul-der. The sides are slightly convex and con-verge, making an even curve with the broadlyarched venter. The ornamentation consistsof strong, sparse ribs and, altogether, sevenrows of tubercles: one row of very hightubercles, slightly elongated radially, justabove the umbilical shoulder; a second rowof less prominent, twice as numerous, radiallyelongated tubercles near the ventrolateralshoulder; a third row, slightly above theventrolateral shoulder, of spirally elongatedtubercles which are less conspicuous andcorrespond in number and position with thetubercles of the second row. The siphonal linebears faint, spirally elongated tubercles thatcorrespond in number with the ventrolateralsand which have been seen only in the im-

I Named after Hacienda Polloc, near which the holo-type was collected.

pressed zone of the holotype, in the venter ofwhich they are absent. The ribs are issued inpairs from the umbilical tubercles and arealmost radial to the second row of tubercleswhere they become lower, more broadlyrounded, and rursiradiate. In later stages,they tend to cross over the venter.REMARKS: Acanthoceras potlocense is char-

acterized by its small size, very depressedwhorl section, and the prominence of theumbilical tubercles.OCCURRENCE: This species is found in the

Romiron formation, in the same localities asA. chasca. The holotype comes from bed 48of the Celendln section.

Acanthoceras sangalense,2 new speciesPlate 53, figures 7-9

One almost complete, partially shatteredspecimen and three whorl fragments are theavailable representatives of this species.Specimen A.M.N.H. No. 27874:1 is theholotype.

DESCRIPTION: The conch is small (none ofthe specimens seems to have been larger than50 mm. in diameter), stout, discoidal, fairlynarrowly umbilicated. The whorl section(fig. 50) is slightly compressed, subrectangu-lar, with high umbilical wall and abruptlyrounded umbilical shoulder. The sides areflattened and subparallel; the ventrolateralshoulder and the venter are rounded. Justabove the umbilical shoulder of the outerhalf whorl there are six strong tubercles,

FIG. 50. Acanthoceras sangalense, new species.Conch section of specimen A.M.N.H. No.27874:1; XI.

slightly elongated radially, from which strongribs are issued generally in pairs. They areprovided with a second row of faint, radiallyelongated tubercles near the ventrolateralshoulder, and a third row of strong, spirallyelongated tubercles just above the ventro-

2 Named after Hacienda Sangal, near which the holo-type was collected.

1956 467

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYlateral shoulder. The ribs, particularly in theouter third, are curved and rursiradiate. Onthe body chamber, all the tubercles becomefaint, and the ribs cross the venter.REMARKS: Acanthoceras sangalense is sim-

ilar in whorl section and ribbing to A. jukes-brownei Spath [Sharpe, 1857 (1853-1857),pl. 17, fig. 2] from the Varians and the sub-globosus zones of the English Cenomanian; itdiffers by the more pronounced developmentof the third row of tubercles and the lessprominent appearance of the tubercles of thesecond row. Acanthoceras pollocense is similarin ornamentation and size to, but is distin-guishable from, A. sa-ngalense by its depressedwhorl section and the fact that the tuberclesof the third row are comparatively fainter.OCCURRENCE: All the specimens were col-

lected from the Romiron formation, in bed 48of the Celendin section, together with A.chasca, A. pollocense, Neolobites kummeli, Lis-soniceras mermeti, and Forbesiceras sp.

FAMILY MAMMITIDAE HYATT, 1900MAMMITES LAUBE AND BRtDER, 1887

Mammites nodosoides afer Pervinqui6rePlate 55, figures 5-8

Mammites nodosoides var. Afra PERVINQUIIRE,1907, p. 310, pl. 18, figs. 2, 2a-b, 3, 3a-b.Mammites nodosoides var. Afra Pervinquiere;BRt7GGEN, 1910, p. 736.Mammites nodosoides var. Afra Pervinquiere;STEINMANN, 1930, p. 148, text fig. 181.Three fragmentary specimens, each being

a whorl fragment of individuals smaller than40 mm. in diameter, and a fourth specimen,a body-chamber fragment of an individual ofabout 200 mm. in diameter (A.M.N.H. No.27875), are referred to this species. They agreevery closely with the description and illustra-tions of the type materials.

DESCRIPTION: The conch is discoidal,fairly narrowly umbilicated. The whorl sec-tion is slightly compressed, subquadrate,with high and steep umbilical wall androunded umbilical shoulder. The sides aredistinctly flattened, the ventrolateral shoul-der is rounded, and the venter is gentlyconvex.Specimen A.M.N.H. No. 27875/1 (pl. 55,

figs. 5-6) has above the umbilical shoulder ofthe last half whorl four radially elongatedtubercles from which one or two prorsiradiate

ribs issue; other ribs are intercalated at aboutthe middle of the sides and make on the outerhalf of the sides a total of nine ribs per halfwhorl. The ribs bear strong conical tuberclesat the ventrolateral shoulders and sharp,strong, spirally elongated tubercles slightlyabove this shoulder. Between these two rowsof tubercles, the ribs are lower and morebroadly rounded than on the sides; they donot cross over the venter.Specimen A.M.N.H. No. 27875 (pl. 55Sfigs. 7-8), a quarter of a whorl, has four

blunt, rounded umbilical tubercles. Corre-sponding with them, on the ventrolateralshoulder, there are four much larger, mas.sive, conical, high tubercles. The ventraltubercles are only faintly indicated. Thetubercles of the umbilical and ventrolateralrows are connected by low and broad ribs.REMARKS: Mammites nodosoides differs

from M. nodosoides afer in that its umbilicaltubercles are conical in all stages. Mammites-nodosoides spinosa Bass6 has horny, spinate,umbilical and ventrolateral tubercles and aquadrate whorl section.OCCURRENCE: Mammites nodosoides aferis a common species in the lower Turonian

Confor formation, in bed 27 of the Tembladerasection (A.M.N.H. No. 27875), in bed 133 ofthe Cajamarca section (A.M.N.H. No.27875/1), in bed 48 of the Polloc section(A.M.N.H. No. 27875/3), and in bed 53 ofthe Celendin section (27875/2). It is associ-ated with Coilopoceras jenksi and Hopli-toides inca. Mammites nodosoides is a commonspecies in the lower Turonian (Salmurian)of Germany and France and is rare in theLabiatus zone of the English Turonian.

PSEUDOASPmDOCERAS HYATT, 1903Pseudoaspidoceras reesidei,' new species

Plate 54, figures 1-4A complete, entirely septate specimen(A.M.N.H. No. 27876:1; pl. 54, figs. 1-2),52 mm. in diameter, is the holotype. Also,four whorl fragments of large ind'ividuals are

referred to this species.DESCRIPTION: The conch is large, dis-

coidal, fairly narrowly umbilicated, withlittle embracing, almost tangential whorls.

1 PseudoasPidoceras reesidei is named after Dr. JohnL. Reeside, who studied some of the earlier collectionsof Cretaceous fossils from the Andes.

468 VOL. 108


The whorl section (fig. 51) is slightly de-pressed, subquadrate, with very steep andhigh umbilical wall and abruptly roundedumbilical shoulder. The sides are flat andlittle converging; the ventrolateral shoulderis rounded, and the venter is broadly vaulted.The whorls quickly increase in size.The holotype has just above the umbilical

shoulder of the last whorl 13 strong, radiallyelongated tubercles from which one or rarelytwo very faint ribs issue. On the ventrolateralshoulder, there is a second row of 18 strongtubercles which in the early part of the volu-tion are slightly radially elongated, but ador-ally they become horn-like. Above theventrolateral shoulder, there is a third row of33 high, subconical to radially elongatedtubercles. Faint ribs connect these three rowsof tubercles but do not cross the venter at anystage; the ribs are prorsiradiate and moreprominent and closely spaced in the earlypart of the outer whorl. The four ventralrows of tubercles are equidistant from oneanother.

Specimen A.M.N.H. No 27876:2 is afragment of a whorl of an individual at least65 mm. in diameter. The umbilical tubercleshave become blunt and conical, the ribs havevanished, the ventrolateral tubercles are veryprominent and conical, and the ventral tuber-cles are rounded and much less conspicuousthan those of the two other rows.

Specimen A.M.N.H. No. 27876:3 (pl. 54,figs. 3-4) is a body-chamber fragment of anindividual about 100 mm. in diameter, inwhich the umbilical and ventrolateral tuber-cles have become rounded, blunt, and lessprominent than in the earlier stages; partic-ularly the umbilical tubercles tend to vanish;the ventral tubercles are very faint and low.The suture (fig. 51) has two saddles on the

sides and a third saddle on the umbilicalshoulder; the first lateral saddle is very nar-row, while the first lateral lobe is extraordin-arily massive, broad, quadrate, and dividedinto two subequal branches by a low butbroad median saddle. It may be that theextraordinary development of the first laterallobe and the reduction of the first lateralsaddle are related to the prominent develop-ment of the ventrolateral tubercles.

REMARKS: Pseudoaspidoceras reesidei, P.michelobensis Laube and Bruder (1887, pl. 25,

fig. 2) and P. footeanum Stoliczka [1861(1861-1866), pl. 52, figs. 1-2] are similar inwhorl section and suture. The first two spe-cies are more narrowly umbilicated than P.footeanum, approaching thus to species of the

A J^

BC

FIG. 51. Pseudoaspidoceras reesidei, new species.Suture line (A) and conch section (B) of specimenA.M.N.H. No. 27876:2; X1.

nodosoides group of the genus Mammites.Pseudoaspidoceras reesidei is distinguishablefrom P. michelobensis by its more crowdedribbing and the radial elongation of the um-bilical tubercles. Pseudoaspidoceras pedro-anum (White), a Brazilian form, has a nar-rower umbilicus than P. reesidei.OCCURRENCE: All the specimens (A.M.N.H.

No. 27876) were collected from the upper partof the Quillquifian group, in bed 24 of theTembladera section, together with Thoma-sites fischeri, Coilopoceras jenksi, Vascocerasaff. V. silvanense, Broggiiceras humboldti, andBroggiiceras olssoni.

Pseudoaspidoceras michelobensis, the closestspecies, is from the lkbiatus zone of the Ger-man Turonian.

FAMILY VASCOCERATIDAE DOUVILLI,1911

BROGGIICERAS,1 NEw GENUS

DESCRIPTION: This genus is created fortwo new species: Broggiiceras olssoni, thegenotype, and B. humboldti, which cannot beincluded in any of the known genera. Theyhave very thick, commonly globose conchs;the whorls have a very high and steep or

overhanging umbilical wall, abruptly roundedumbilical shoulders, more or less convergingconvex sides, and rounded venter. The orna-

1 Broggiiceras is named in honor of Ing. Jorge A.Broggi, director of the Instituto Geol6gico del Per(u.

1956 469


mentation consists of single, radial ribs; theyare more conspicuous, or present only in theouter third of the sides and on the venter. Theribs appear very late in the ontogeny (be-tween radii of 20 and 30 mm.) and becomestronger in the body chamber. The suture hastwo or three saddles on the sides; they arevery large, broad, with phylloid endings, andregularly decreasing in size. The lobes arevery small and slender; the first one is V-shaped and may be either trifid or bifid.REMARKS: In shape, whorl section, and

suture, Broggiiceras is similar to the closelyrelated Turonian genera Vascoceras andFagesia. These two genera, however, havestrong umbilical and ventral tubercles andribs which start at the umbilical shoulder;furthermore, their ribs and tubercles disap-pear very early in the ontogeny, the lattervolutions being smooth.

Fagesia (?) fleuryi Pervinquiere (1907,p. 330) is included with'in Broggiiceras. It isspherical in shape, lacks tubercles, and hasfaint ribs, which are better developed on theventer and attenuated on the sides. Pervin-quiere said about this form: "Ce n'est pas sanquelque hesitation que je rapporte cetteammonite au genre Fagesia; si elle en a laforme gen6rale, l'ornementation presentedes diff&rences importantes."

Broggiiceras olssoni,' new speciesPlate 55, figures 1-4

Vascoceras amieirensis Choffat; LIss6N, 1908,p. 9c, pI. 9.Seven entire discs, one half a disc, and two

whorl fragments are considered within thisspecies. Specimen A.M.N.H. No. 27877:5(pI. 55, figs. 1-2), the outer half whorl ofwhich belongs to the body chamber, is desig-nated the holotype.

MEASU1EMENTSA.M.N.H.

Nos.27877:127877:227877:327877:427877:527877:627877:727877:8

D H D/HI T D/T U D/U315262.56578848993.5

1423273037364238.5

.45

.44

.43

.46

.47

.43

.47

.41

1527.5343941484845

.48

.53

.54

.60

.53

.57

.54

.48

71419.516202422.530

.23

.27

.31

.25

.26

.29

.25

.32I Named after Dr. Alex A. Olsson, who has contrib-

uted greatly to the knowledge of South AmericanMesozoic and Cenozoic faunas.

DESCRIPTION: The conch is subglobose,stout, narrowly umbilicated. The whorl sec-tion is subquadrate, changing from com-pressed in the inner whorls to slightly de-pressed in the body chamber, with very highand perpendicular umbilical wall andabruptly rounded umbilical shoulder. Thesides are convex and subparallel, the ventro-lateral shoulder is very broadly rounded, andthe venter is gently vaulted. The outer whorlof the holotype has 30 straight, radial, low,subangular ribs which are more conspicuouson the venter and on the outer third of thesides. They are almost obliterated along themiddle of the sides, although a few reach theumbilical shoulder as very faint folds. Theribs appear at about a radius of 20 to 25 mm.,and are stronger on the body chamber.The suture has two broad, large saddles on

the sides and a third saddle on the umbilicalshoulder. The ventral lobe has parallel sides;the lateral lobes are small and V-shaped.Both saddles and lobes are equally denticu-lated; the saddle endings are phylloid.REMARKS: Broggiiceras fleuryi (Pervin-

quiere) has a more globose shape, narrowerumbilicus, and fewer ribs than B. oissoni.The specimen described by Liss6n as Vas-

coceras amieirensis is from the same localityas the collection here studied. As is the casewith most of the specimens from the locality,it is weathered and does not show the ribs.OCCURRENCE: Broggiiceras oissoni is found

in the upper part of the Quillquifnan group,in bed 24 of the Tembladera section, associ-ated with B. humboldti, Thomasites fischeri,Pseudoaspidoceras reesidei, and Coilopocerasjenksi.

Broggiiceras humboldti,2 new speciesPlate 56, figures 3-6

Three complete, slightly weathered stein-kerns are assigned to this species. SpecimenA.M.N.H. No. 27878:3 (pl. 56, figs. 5-6),including part of the body chamber, is theholotype.A.M.N.H.

Nos.27878:127878:227878:3

MEASUREMENTSD H D/Il T D/T U D/U63 31 .49 32 .51 12 .1982 44 .49 47 .57 10 .12100 48 .48 43 .43 16 .16

2 Named after Alexander von Humboldt, who in 1802collected the first Peruvian Cretaceous fossils to bedescribed scientifically.

470 VOL. 108


DESCRIPTION: The conch is subglobose,stout, narrowly umbilicated. The whorl sec-tion changes from depressed in the earlywhorls to compressed in the body chamber;at the same time, the very high umbilicalwall changes from perpendicular to over-hanging, and the umbilical shoulder changesfrom indistinct to abruptly rounded. Thesides are gently convex and converging; theydecrease in convergence during growth. Theventrolateral shoulder is indistinct, and theventer is narrowly rounded. Only at a radiusof 32 mm., strong, subrounded, widely spacedribs appear; there are 11 per half whorl. Theribs are more conspicuous on the venter andthe ventrolateral shoulders and flatten out atabout the middle of the sides. The suture hasthree broad, denticulated saddles on thesides and a fourth saddle on the umbilicalshoulder. The lobes are smaller and nar-rower; the first lobe is V-shaped and may bebifid or pointed.REMARKS: Broggiiceras humboldti is distin-

guishable from B. olssoni by its smaller umbil-icus, less numerous and stronger ribs, and thefact that the whorl becomes compressed andhigh in the later stages.OCCURRENCE: This species is found in the

upper part of the Quillquifian formation, inbed 24 of the Tembladera section, associatedwith B. olssoni and the ammonites alreadylisted under the latter species.

VASCOCERAS CROFFAT, 1898Vascoceras cf. V. silvanense Choffat

Plate 56, figure 7A small, entirely septate specimen is com-

parable to V. silvanense Choffat [1898(1885, 1898), p. 57, pl. 18, fig. 5, pl. 21, fig. 9].DESCRIPTION: The conch is subglobose,

stout, narrowly umbilicated. The whorl sec-tion is slightly depressed, with high umbilicalwall and rounded shoulder. The sides arebroadly convex and converge towards thenarrowly rounded venter; the ventrolateralshoulder is indistinct. In the outer whorl,slightly above the umbilical shoulder, thereare five high and rounded tubercles.REMARKS: Specimen A.M.N.H. No. 27879

(pl. 56, fig. 7) differs from the specimens ofV. silvanense illustrated by Choffat only byits less depressed whorl section.OCCURRENCE: Quillquifian group, bed 24

of the Tembladera section.

THOMASIThS PERVINQUIkRE, 1907Thomasites fischeri,' new species

Plate 56, figures 1-2; plate 57, figures 1-3

Three somewhat weathered steinkerns areincluded in this new species. SpecimenA.M.N.H. No. 27880:3, entirely septate, ischosen as the holotype.

MNAtREA NTS

A.M.NM.Nos.

27880:127880:227880:3

D H D/H T51.5 25 .49 31.586 42 .49 45105 52.5 .50 54

D/T U.61 10.5.52 17.51 18

D/U.20.20.17

DEscRIPTIoN: The conch is subglobose,stout, narrowly umbilicated. The whorl sec-tion is compressed and changes from subrec-tangular in the inner whorls to narrowlyrounded ventrally in the outer ones. The um-bilical wall is high and perpendicular, andthe umbilical shoulder is rounded but dis-tinct. The sides are broadly convex andchange from subparallel to strongly conver-gent. The ventrolateral shoulder is wellmarked in the inner whorls but indistinctin the latter ones. The venter changes frombroadly vaulted to narrowly rounded.Above the umbilical shoulder, there is a

row of four strong, rounded, blunt tubercleswhich appear at a radius of 20 mm. andvanish at a radius of 35 mm. They are nolonger visible in the outer whorl of any ofthe available specimens. The distinct ventro-lateral shoulders of the inner volutions bearblunt, elongated spirally, faint tubercles, ofwhich there are about seven irn one-quarterof a whorl. Also, the siphonal line is raised,forming a low, faint, rounded carina pro-vided with weak, spirally elongated tubercleswhich correspond with the ventrolateral onesalthough they are set slightly forward. Fromthe ventrolateral tubercles, faint ribs aredirected dorsally, but they flatten out beforereaching the middle of the sides. All orna-mentation is lost in the outer whorls. Thesuture has three saddles on the sides and a

fourth saddle on the umbilical shoulder; theyare very broad, low, denticulated, and withphylloid endings. The first lateral lobe hastwo branches, the inner one being larger.REmARKS: Thomasites fischeri is similar to

T. jordani Pervinquiere in shape, whorl sec-

1 Named in honor of Prof. Alfred G. Fischer.

4711956


tion, suture, and ornamentation. Pervin-quibre described several varieties which differfrom one another more than the Peruvianspecies does from the "forme typique" of T.jordani. Thomasites jordani costata has verystrong ornamentation; T. jordani taevis hasangular ventrolateral shoulders and veryfaint ornamentation. Thomasites fischeri isdistinguished from T. jordani, forma typica,by its very faint ornamentation, the lack ofribs on the sides, and the early disappearanceof the tuberculation. Thomasites fischeri andT. jordani differ from all other species ofThomasites by the presence of siphonaltubercles. It may be advisable to separatethem in a new genus.OCCURRENCE: Thomasites fischeri has the

same occurrence and association as Broggi-iceras olssoni. Thomasites jordani is fromthe lower Turonian of Tunisia. Fritzsche(1924, p. 326) reports T. cf. jordani var.kdevis Pervinquiere from Cundinamarca,Colombia, associated with T. rollandi,Fagesia peroni var. columbiana Fritzsche, andPseudotissotia douvilki, all lower Turonianspecies.

FAMILY PERONICERATIDAE HYATT, 1900TEXANITES SPATE, 1932

Texanites hourcqi CollignonPlate 58, figures 6-7

Texanites hourcqi COLLIGNON, 1948, p. 78, pl.7, figs. 1, la-b, pl. 10, figs. 1, la.A single completely septate, fragmentary

steinkern has been assigned to this species.MEASURMENTS

A.M.NH. No. D H D/H T D/T U D/U27881 100 34.5 .34 29.5 .29 41 .41

DESCRIPTION: The conch is large, dis-coidal, platy, widely umbilicated. The whorlsection is compressed, subrectangular, withhigh, perpendicular, and slightly concaveumbilical wall and very distinct umbilicalshoulder. The sides are slightly convex andconverging. The greatest whorl thickness isat about the end of the inner third and isabout four-fifths of the whorl height. Theventer is provided with a median, low, butdistinct carina bounded by two wider andshallow grooves. There are about 12 ribs in aquarter of a whorl. They bear five rows of

tubercles. The first row, at the umbilicalshoulder, has pointed and conical tubercleswhich are the starting points of the primaryribs; the second row, at the end of the innerthird, has pointed, radially elongated tuber-cles; the third row, near the end of the middlethird, has similar but less conspicuoustubercles; the fourth row, at about the middleof the outer third, has rounded tubercleswhich are stronger than those of the thirdrow; and the fifth row, at the ventrolateralshoulder, has sharp, spirally elongated andhigh tubercles which are higher than thesiphonal carina. Most of the ribs, which arelow and rounded, start (rarely in pairs) fromthe umbilical tubercles. Several are inter-calated at about the second or third rows oftubercles. The suture has two saddles on thesides and a third saddle on the umbilicalshoulder; the first one is very large, broad,quadrate, and divided by a median lobule.The first lateral lobe is very deep andpointed; the second one is bifid.OCCURRENCE: Specimen A.M.N.H. No.

27881 was collected from the upper part ofthe Celendin formation (Lenticeras baltaizone), in bed 72 of the Celendfn section, to-gether with Desmophyllites gaudama, Lenti-ceras baltai, and Tissotia steinmanni.SUPERFAMILY TISSOTIACEAE HYATT, 1900FAMLY COILOPOCERATIDAE HYATT, 1903

COILOPOCERAS HYATT, 1903Coilopoceras jenksi,1 new species

Plate 59, figures 3-4; plate 60, figure 7Cf. Coelopoceras Requieni; BR#GGEN, 1910, p.

733, text fig. 12.Ten steinkerns are assigned to this species.

Specimen A.M.N.H. No. 27882 is the holo-type.

MEASUREMENTSA.M.NfH.

Nos.27882/3:12788227882/1:1

D H D/H T D/T U D/U95 57135.5 81.5157 93

.60 20 .21 2.5 .03

.60 39 .29 3.5 .03

.59 37 .24 4.5 .03

DESCRIPTION: The conch is large, lenti-cular, with almost closed umbilicus. Thewhorl section is a very compressed and high,helmet-shaped ogive, with steep umbilical

1 Named in honor of Prof. William F. Jenks.

472 VOL. 108


wall and rounded but distinct umbilicalshoulder. The sides are smooth, gently con-vex, diminishing in convexity in the outerthird, where they may even be slightly con-cave; they converge towards the fastigate,narrowly rounded venter. The greatest whorlthickness is at about the middle of the sidesand is about one-third of the whorl height.The suture (fig. 52) has four saddles on thesides, the first saddle being broad, massive,

which has a larger number of very frilledsaddles. Coilopoceras lentiformis (von Koen-en, 1897, p. 11), another smooth form, has amore inflated whorl section, and its greatestwhorl thickness is about one-half of the whorlheight.OCCURRENCE: Coilopoceras jenksi is the

most common ammonite in the lower Turo-nian Cofior formation. It has been collectedin the following localities:

Au

B

C.-FIG. 52. Coilopoceras jenksi, new species. A, B, C.

Suture lines of specimens A.M.N.H. Nos. 27882/2,27882/1: 1, and 27882 (holotype); XI.

denticulated, and often divided into twobranches by a median lobule; the othersaddles are more or less denticulated andregularly decrease in size. The first laterallobe is very distinct; it is very broad and isdivided by a deep, median saddle into twobranches, in turn bifid. The other lobes aremuch narrower than the saddles, strangu-lated, and digitated.

REMARKS: Coilopoceras jenksi is similar inshape, whorl section, and suture to C.requianus d'Orbigny; it can be distinguishedby its thicker whorl section and the lack ofthe faint, flexuous ribs present in the latterspecies. Coilopoceras lesseli Briiggen, anotherPeruvian species, is similar in shape, but thelateral saddles are Tissotia-like, entire, androunded, a character that is not present inany of the specimens referred to C. jenksi.Coilopoceras springeri Hyatt, from the NorthAmerican Turonian, is a large-sized species

A.M.N.H.Nos.

2788227882/127882/227882/327882/4

BED

27133425355

SECTION No. OF

Tembladera 1Caiamarca 4LajasCelendfnPolloc

13I

It is usually associatedwithHoplitoides inca,Mammites nodosoides afer, Pseudoaspidocerasreesidei, Thomasites fischeri, Broggiiceras ols-soni, and B. humboldti.

Coilopoceras newelli, new speciesPlate 61, figures 4-5; plate 62, figures 5-7

Coelopoceras n. sp. A aff. C. kessel Briiggen andC. springeri Hyatt; REESIDE, 1927, in Wassonand Sinclair, p. 1270, pl. 9, figs. 1-2.

1 This new species is named in honor of Prof. Nor-man D. Newell, who suggested to the present writerthe problem dealt with in this monograph.

19S6 473

;


Twenty-two steinkerns, including severalentire discs, are available for study. SpecimenA.M.N.H. No. 27883/7 is the holotype. Mostof them show a peculiar mode of preservation.The inner volutions of the steinkern aremissing, and the outer and only presentvolution has been compressed, closing thegap left by the missing inner volutions (pi.62, figs. 5-7). Apparently the sediment filledonly the outer whorl of the shell; afterconsolidation, the shell was dissolved away,and an empty space was left inside the speci-

DESCRIPTION: The conch is large, lentic-ular, narrowly umbilicated, with a tendencyin later stages to become more widely um-bilicated. The whorl section is a very highand compressed ogive, with very shortand almost indistinct umbilical wall androunded umbilical shoulder. The sides areevenly convex and converge towards thefastigate, sharp venter. The greatest whorlthickness is at about the middle of the sidesand is about two-thirds of the whorl height.There are broad, fold-like, radially elongated

tA

B

C

DFIG. 53. Coilopoceras newelli, new species. A, B, C, D.

Suture lines of specimens A.M.N.H. Nos. 27883:3, 27883:1,27883:7 (holotype), and 27883:6. A, B, XI; C, D, X1/2.

men by the removal of the inner whorls whichwere not filled with sediment. Later, pressure,either gravitative or tectonic, compressed thesteinkern, closing the gap left by the innerwhorls.

MEASUREKENTSA.M.N.H. Nos.

27883:127883:227883:327883:427883:527883:627883:7

D150

185199215272330365

H

748798107132159171

D/H.49.47.49

.49

.49

.48

.47

T474753

D/T.31.25.27

U

17183022345773

D/U.11.10.15.10.13.17

.20

swellings which begin at about the middle ofthe inner third and vanish before the end ofthe middle third. They may appear in thephragmocone (pl. 62, fig. 5) or only in thebody chamber (pl. 61, fig. 4). Apparentlythose specimens with thicker whorl sectionshave stronger ornamentation. All the avail-able specimens show well the suture (fig.53); and, although no two specimens havean identical suture, the basic pattern is thesame. On the sides there are seven saddles;the first saddle is narrow, conspicuouslystrangulated, and with either two or three

474 VOL. 108


branches; the second lateral saddle is verybroad, massive, and is always divided by amore or less deep median lobule; the tworesulting branches can be either entire, givinga Sphenodicus-like saddle, or crenulated. Thethird lateral saddle is usually much smallerthan the second one and can be either entire(Tissotia-like) or, more commonly, with asmall median denticle or sometimes severalof them. The other saddles are usually entire,but, again, they may be indented. The firstlateral lobe is extraordinarily broad, and inthe most simple cases it is deeply divided intotwo branches by a saddle which commonly isentire and rounded but which may be quad-rate and even crenulated. The two resultingbranches are, in turn, bifid and more or lesssubdivided by saddles which may, excep-tionally, be larger than the median saddle;usually the inner branch is more developed.The other lobes are much narrower, usuallystrangulated, and bifid.

REMARKS: Coilopoceras newelli is similar insize, whorl section, and suture to C. springeriHyatt (1903, p. 96), a poorly known species,from which it differs by the presence of ribs,the wider umbilicus, and smaller number ofsaddles in the suture. Coilopoceras kentiformisvon Koenen (Solger, 1904, p. 136), C. lesseli,and C. jenksi are forms with almost closedumbilicus. Coilopoceras n. sp. B Reeside(1927, in Wasson and Sinclair, p. 1278), aform with almost closed umbilicus and fineflexuous ribs, seems to be very closely relatedto, if not conspecific with, C. kentiformis vonKoenen.OCCURRENCE: Coilopoceras newelli is a

very common species in the upper TuronianCajamarca formation.

A.M.N.H. BED

Nos.

27883 227883/1 14127883/2 66

BCP

HOPLITOIIES

Hoplitoides

Plate 63,

Nine steinkerns, iidiscs, are available. S27884:1 (pl. 63, figs.

MEASUREMENTSA.M.N.H. Nos.

27884/1:127884:227884:327884/227884:1

D353547.5104.5116

H1920266267

D/H T.54 -.57 11.5.55 14.5.59 24.58 34

D/T

.33

.31

.23

.29

u2243

D/U.06.06.10.02

DESCRIPTION: The conch is discoidal,platy, with the umbilicus almost closed. Thewhorl section is very compressed and high,with short and perpendicular umbilical walland with distinct but rounded umbilicalshoulder. The sides are gently arched andconverge towards the truncated venter whichis subconcave to flat and bordered by tworaised lines. The greatest whorl thickness isat about the middle of the sides and is about

tA

A

BFIG. 54. Hoplitoides inca, new species. A, B.

Suture lines of specimens A.M.N.H. Nos. 27884:1(holotype) and 27884/2: 1; X 1.

one-half of the whorl height. The holotypehas smooth sides, but the inner whorl, ob-tained from a similar specimen (A.M.N.H.No. 27884; pl. 63, fig. 6), shows that, at leastup to a diameter of 45 mm., there are faint,falciform ribs which are particularly notice-able in the outer third of the sides and underadequate lighting. The other small steinkerns

No. oF do not show any ornamentation; this may beSECTION SPECIMENS owing to their somewhat weathered condi-

ambamarca 18 tion. The suture (fig. 54) has four to fiveambamarca 28 saddles on the sides, of which the first saddleaoamarca 2 is large and with two or three branches; the

others are low, broad, and slightly denticu-lated. The first lateral lobe has two branches

VON KoENEN, 1898 which may be equally developed or not, andaca, new species which in turn are denticulated.

REMARKS: Hoplitoides inca is similar infigures 6-11 shape, whorl section, and suture to H.ncluding four complete munieri Pervinquiere (1907, p. 217), but ispecimen A.M.N.H. No. distinguishable by the presence of faint,7-8) is the holotype. falciform ribs in the inner whorls. Hoplitoides

1956 475


mifabilis Pervinquibre differs from H. miu-nieri only in the suture details, which the pres-ent writer feels cannot be taken as specificdifferences. Hoplitoides ingens von Koenen isan altogether different species, with trun-cated venter only in the younger whorls, andwhich becomes fastigate, sharp-ventered inmaturity. It may be necessary to separate thegroup of Senonian species of Hoplitoides, withfastigate venter in the later whorls, from theTuronian species such as H. munieri and H.i-lca in which the venter is truncated in allstages.OCCURRENCE: Hoplitoides inca occurs in

the lower Turonian Cofior formation, inbeds 39 and 42 of the Lajas section(A.M.N.H. Nos. 27884 and 27884/1) and inbed 55 of the Polloc section. It is associatedwith Coilopoceras jenksi and Mammitesnodosoides afer. Hoplitoides munieri occursin the lower Turonian of Tunisia.

FAMILY TISSOTImAE HYATT, 1900BARROISICERAS DE GRossouviE, 1894

M?arroisiceras (Barroisiceras) haberfellUneri(von Hauer)

Plate 57, figures 4-5Ammoniteskhaberfellneri VON HAUER, 1866, p.

301, pl. 1, figs. 1-5.Barroisiceras haberfellneri von Hauer; BASS{,

1947, p. 114, cum synon.A single, poorly preserved fragment is

tentatively referred to this species(A.M.N.H. No. 27885).DESCRIPTION: The conch is discoidal, nar-

rowly umbilicated. The whorl section is highand compressed, with high umbilical walland rounded but distinct umbilical shoulder.The sides are subflattened and converge to-wards the broad, roof-shaped venter whichis provided with a low carina. The ventro-lateral shoulders are distinct. Just above theumbilical shoulder, there are about 10radially elongated tubercles which send outone or two slightly prorsiradiate ribs; thereare also a few intercalated ribs. All end at theventrolateral shoulder in spirally elongatedtubercles, of which there are about eight in aquarter of a whorl. The siphonal carina isalso provided with spirally elongated tuber-cles which correspond with the ventrolateralones although slightly set forward.REMARKS: Specimen A.M.N.H. No. 27885

compares fairly well with von Hauer'sschematic illustration of the holotype. Thereis, however, considerable confusion about thisspecies, and, lacking an adequate sample,the present writer prefers to leave thisdetermination open.OCCURRENCE: The specimen was collected

from the lower part of the Celendin forma-tion (Buchiceras bilobatum zone), in bed 15of the Bambamarca section. Barroisicerashaberfellneri is a very common and wide-spread species which usually is taken as anindex of the lowest Senonian.

Barroisiceras (Barroisiceras) kayi,1 newspecies

Plate 57, figures 6-7Two well-preserved entire specimens and

two whorl fragments are assigned to thisspecies. Specimen A.M.N.H. No. 27886: 1,with the beginning of the body chamber, isthe holotype.

MEASU IMENTSA.MN.H. Nos.

27886:127886:2

D H D/II T D/T U D/U84 43 .51 27 .32 17 .2092 46 .50 28 .30 18 .20

DESCRIPTION: The conch is discoidal,platy, narrowly umbilicated. The whorl sec-tion is high, compressed, rectangular, withhigh and perpendicular umbilical wall androunded but distinct umbilical shoulder. Thesides are flattened, subparallel, and slightlyconverging. The ventrolateral shoulder iswell marked, and the venter is broad, roof-shaped, and provided with a low and roundedcarina. The greatest thickness is near theumbilical shoulder and is less than two-thirds of the whorl height. Just above theumbilical shoulder of the outer whorl of theholotype is a row of blunt tubercles slightlyelongated radially; they are the startingpoints of single, slightly prorsiradiate, al-most straight, low and broad but distinctribs. At about the middle of the sides, singlesecondary ribs are intercalated. All the ribsend at the ventrolateral shoulder in verystrong, blunt, spirally elongated tubercleswhich are twice as numerous as the umbilicalones. The low siphonal carina is providedwith a row of spirally elongated tubercleswhich correspond with the ventrolateralones, although slightly set forward. The su-

I Named in honor of Prof. Marshall Kay.

VOL. 108476


ture has three broad bifid saddles on the sidesand a third saddle on the umbilical shoulder;they have phylloid terminations. The lobesare narrow; the first lobe is deeper than theventral one and is pointed; the second one isbifid.REMARKS: Barroisiceras (Barroisiceras)

kayi is similar in suture, whorl section, andpattern of ornamentation to B. (B.) haber-fellneri from which is it distinguishable byfewer umbilical tubercles, the lack of forkingribs, its rectangular whorl section, and theregularity of the ribbing. Another similarspecies is B. (B.) onilahyense Bass6 (1947, p.100) which has less pronounced ribbing andforking ribs.OCCURRENCE: Barroiscerias (B.) kayi is

found in the Celendin formation (Buchicerasbilobatum zone), in bed 69 of the Celendinsection (A.M.N.H. No. 27886), in bed 144 ofthe Cajamarca section (A.M.N.H. No.27886/1), and in bed 15 of the Bambamarcasection. It is associated with Buchiceras bilo-batum, Heterotissotia lissoni, H. bucheri, andseveral species of Tissotia and Barroisiceras.

Barroisiceras (Solgerites) brancoi (Solger)Plate 58, figures 1-4

Barroisiceras Brancoi var. mitis SOLGER, 1904,pl. 5, figs. 4a-b, 5.

Barroisiceras Brancoi var. mite Solger; BRtfG-GEN, 1910, p. 732, text fig. 11.

Schloenbachia (Barroisiceras) Brancoi var. mitisSolger; LftHY, 1918, p. 48, pl. 4, figs. la-b.

Schloenbachia (Barroisiceras) sp. nov. sp. LtTHY,1918, p. 49, pl. 4, figs. 2a-b.

Barroisiceras Brancoi mite Solg.; STEINMANN,1930, p. 163, figs. 196A-C.

Barroisiceras (Solgerites) brancoi var. miteSolger; REESIDE, 1932, p. 14.

Solgerites brancoi Solger; BASSA, 1947, p. 123.Two entire steinkerns and one whorl frag-

ment are referred to this species.MEASEME:NTS

A.M.N.H. No.27887/1

D H D/H T D/T U D/U55 28.5 .52 15 .27 7.5 .14

DESCRIPTION: The conch is discoidal,platy, very narrowly umbilicated, with a

tendency to become more widely umbilicatedin later stages. The whorl section is veryhigh and compressed, with low and verysteep umbilioal wall and abruptly roundedumbilical shoulder. The sides are flattened

and parallel; the ventrolateral shoulders aredistinct, particularly in the smaller diam-eters. The venter is roof-shaped and pro-vided with a carina. The greatest thickness isat about the middle of the sides and is aboutone-half of the whorl height. The umbilicalshoulder has about six weak, radially elon-gated tubercles per whorl; they are the startingor forking points of broad, faint ribs; otherribs are intercalated at about the middle ofthe sides. All the ribs end at the ventrolateralshoulder in distinct, blunt tubercles, of whichthere are about 35 per volution. The siphonalcarina is provided with high, sharp, spirallyelongated tubercles which are set slightly for-ward of the corresponding ventrolateral pair.Between the radii of 25 and 35 mm., theornamentation tends to vanish. The umbilicaltubercles and the ribs disappear first, and theventrolateral tubercles follow, producingthus a smooth, rounded ventrolateral shoul-der. Finally the siphonal tubercles disappear,leaving a fastigate venter. The suture hasthree saddles on the sides; they have distinctfestoon-like endings; the first lateral lobe isbifid.

REMARKS: Specimen A.M.N.H. No. 27887/1(pl. 58, figs. 1-2) has been included withinB. (Solgerites) brancoi with certain hesi-tancy. It has a more pronounced ornamenta-tion than most specimens of this species haveat that diameter. Barroisiceras (Solgerites)brancoi is similar to B. (Solgerites) armatumin whorl section and suture; the latter,however, lacks ventrolateral tubercles, isless closely ribbed than B. (S.) brancoi, anddevelops ventrolateral spines in later stages.The subgenus Barroisiceras (Solgerites) Ree-side differs from Barroisiceras (Barroisiceras)only by its attenuated ornamentation.OCCURRENCE: Barroisiceras (S.) brancoi

occurs in the Celendin formation (Buchicerasbilobatum zone), in bed 69 of the Celendinsection (A.M.N.H. No. 27887), and in bed 75of the Polloc section (A.M.N.H. No.27887/1). The associated species are the sameas those listed for B. (B.) haberfellneri.

Barroisiceras (Forresteria) basseae,1 newname

Plate 58, figure 5Barroisiceras Haberfellneri v. Hauer; BRtGGEN,

1910, p. 730, text fig. 10.

1Named in honor of Mile. Eliane BassE.

1956 477

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYBarroisiceras Haberfellneri v. Hauer; STEIN-

MANN, 1930, p. 162, figs.195A-C.Non Barroisiceras braiggeni KNECHTEL, 1947,

in Knechtel, Richards, and Rathbun, p. 123, pl.41, figs. 2-4.

Harleites (?) bri2ggeni BASSaI, 1947, p. 141.An entirely septate, complete steinkern,

which has been fractured along the siphonalline, and a whorl fragment are referred to thisspecies.

MEASUISA.M.NH. No.

27888D H D/Hl T D/T U D/U94 43 .46 26 .28 22 .23

DEscluRPnoN: The conch is discoidal,platy, narrowly umbilicated. The whorl sec-tion is high, very compressed, rectangular,with overhanging umbilical wall and abruptlyrounded umbilical shoulder. The sides areflat and parallel; the ventrolateral shoulderis rounded but well marked, and the venteris broad, roof-shaped, and provided with acarina. The greatest whorl thickness is atabout the middle of the sides and is nearlytwo-thirds of the whorl height.

Single, low, and broad ribs (about nine perwhorl) begin in the umbilical shoulder. Theyare radiate, and at about the middle of thesides, they develop into pointed, strongtubercles, slightly elongated radially, inwhich the ribs fork. At this level, also, a fewribs are intercalated. All the ribs (about 22ribs in the outer half of the sides) end at theventrolateral shoulder in very strong, blunt,spirally elongated tubercles. The siphonalcarina bears spirally elongated tubercleswhich are set forward of the correspondingventrolateral pair. The suture has threebroad, distinctly bifid saddles, with festoon-like terminations The first lateral lobe is verydeep and trifid; the second lateral lobe isbifid.

REMARKS: The specimen illustrated bySteinmann (1930) as B. haberfellneri agreesin al respects with the specimens here dis-cussed. That specimen in all probability isone of the two specimens that Bruggen (1910)descibed under that same name. Also, thesuture illustrated by Steinmann is the samepublished first by Brtggen, and moreover,th-e locality given by both of them is thesame.On the basis of Bruggen's description,

Bass6 (1947, p. 141) erected the speciesBarroisiceras (Harleites) (?) briggeni (namepreoccupied by Barroisiceras briiggeni Knech-tel, 1947). The subgenus Hareites, however,includes species which have a very narrowumbilicus, very attenuated ornamentation,and very weak mediolateral tubercles. Bar-roisiceras (Forresteria) basseae is similar to B.(Aistadensis) severiense Reeside (1932, p. 16)and B. (Forresteria) stantoni Reeside (1932,p. 17); the former has pronounced umbilicaltubercles, lacks forking ribs, and its ventro-lateral tubercles are not so numerous nor soprominent as those of B. (F.) basseae; B.(Alstadensis) severiense has been trans-ferred by Bass6 (1947) to the subgenusForresteria. Barroisiceras (Forresteria) stan-toni has a much wider umbilicus and thickerwhorl section than B. (F.) basseae. In shape,suture, and whorl section, B. (F.) basseae issimilar to B. (F.) ampozaloakaense Bass6; thelatter differs, because it lacks the forkingribs and its mediolateral tubercles disappearvery early in the ontogeny.OCCURRENCE: Barroisiceras (Forresteria)

basseae is found in the Celendin formation(Buchiceras bilobatum zone), in bed 144 of theCajamarca section (A.M.N.H. No. 27888),and in bed 15 of the Bambamarca section(A.M.N.H. No. 27888/1). The associatedspecies are the same as those listed for B.(Barroisiceras) haberfellneri.

Barroisiceras (Forresteria) alluaudi Boule,Lemoine, and Th6venin

Plate 61, figure 1Acanthoceras (Prionotropis) Alluaudi BOULE,

LEMOINE, AND THIVENIN, 1907 (1906-1907), p.12, pl. 1, figs. 6, 6a, 7.Prionotropis alluaudi Boule-Lemoine-Thevenin;

Liss6N, 1908, p. 17, p1. 17.Prionotropis Aliuaudi Boule, Lem. et Th.;BRttGGEN, 1910, p. 722.Barroisiceras (Forresteria) allaudi Boule, Le-

moine, and Thivenin; REESIDE, 1932, p. 12.Forresteria alluaudi blt.; BAss*, 1947, p. 128,

cum synon., p1. 14, figs. 3, 3a, pl. 15, figs. 2, 2a.A single, fairly well-preserved, entirely

septate steinkern, which comprises three-fourths of a whorl, is referred to this species.

MfASU"RMNTSA.M.NIH No.

27889D H D/H T D/T U D/U

48.5 21 .43 17.5 .36 15 .35

VOL. 108478


DESCRIPTION: The conch is stout, small,discoidal, widely umbilicated. The intercos-tal whorl section is slightly compressed,subquadrate to subcircular, with high andsteep umbilical wall. The sides are broadlyconvex; the ventrolateral shoulders arerounded; the venter, which in our specimenis poorly preserved, is supposed to be roof-shaped and with a low carina; and thegreatest whorl thickness is at about the mid-dle of the sides and is slightly smaller thanthe whorl height. The costal whorl section ispolygonal and slightly depressed.Specimen A.M.N.H. No. 27889 has, in the

umbilical shoulder of the last half whorl, fiveweak tubercles which are slightly elongatedradially. They send out single, rounded ribswhich, by the middle of the sides, developinto strong, large, and rounded tubercles.From each tubercle two ribs fork, and occa-sionally there is an intercalated rib startingjust above the middle of the sides. All theribs end in strong, rounded, and high ventro-lateral tubercles. The specimen has the ven-ter weathered, but it is still possible to see theremains of a nodose carina.

REMARKS: Barroisiceras (F.) alluaudi isvery closely related to, if not conspecificwith, B. (F.) forresteri Reeside (1932, pl.5, figs. 2-7); they are separable only by thespinose character of the ornamentation in thelatter species.

OCCURRENCE: Barroisiceras (F.) alluaudi isfound in the Celendin formation (Buchicerasbilobatum zone), in bed 144 of the Cajamarca(A.M.N.H. No. 27889). It is associated withspecies of the following genera: Buchiceras,Heterotissotia, Tissotia, B. (Barroisiceras),and B. (Solgerites). Liss6n (1908) describedtwo specimens from Cajabamaba, and Bruig-gen reports one from Otuzco. Barroisiceras(Forresteria) forresteri occurs in the Mancosshale, 200 feet above the Ferron sandstonemember, Utah.

TISSOTIA DOUVILLi, 1890

Tissotia steinmanni Liss6n

Plate 61, figures 2-3

Tissotia steinmanni LIss6N, 1908, p. 1, pl. 1.7issotia steinmanni Liss6n; KNECETEL, 1947,

in Knechtel, Richards, and Rathbun, p. 111, pl.32, fig. 2, pl. 33.

DESCRIPTION: Three fragmentary butwell-preserved steinkerns (A.M.N.H. No.27890) are referred to this species.

DESCRIPTION: The conch is large, lentic-ular, and very narrowly umbilicated. Thewhorl section is a very high and compressedogive. The smooth sides converge towards thesharp, fastigate venter with gentle convexity.The greatest whorl thickness is in the innerthird and is about one-third of the whorlheight. The suture (fig. 55) has six saddles on

FIG. 55. Tissotia steinmanni Liss6n. Sutureline of specimen A.M.N.H. No. 27890:1; XI.

the sides; the first one is deeply divided by abifid lobule; the others are characteristicallyrounded and entire. The lobes are broad anddenticulated. The ventral lobe has a broad,quadrate siphonal saddle.REMARKS: Tissotia steinmanni resembles

T. reesideana Knechtel in suture and lack ofornamentation; they are separable by themore inflated whorl of the latter.OCCURRENCE: This species is found in the

Celendin formation (Lenticeras baltai zone),in bed 72 of the Celendin section, asso-ciated with Desmophyllites gaudama, Tex-anites hourcqi, Lenticeras baltai, and Tissotiafourneli.

Tissotia hami KnechtelPlate 62, figures 1-2

Tissotia halii KNECHTEL, 1947, in Knechtel,Richards, and Rathbun, p. 120, pl. 41, figs. 1-5.

Two whorl fragments (A.M.N.H. No.27891) are availabe for study.

DESCRIPTION: The conch is large, discoidal,narrowly umbilicated. The intercostal whorlsection is compressed, with low umbilicalwall and broadly rounded umbilicalshoulders. The sides are slightly convex andconverging. The ventrolateral shoulders are

very broadly rounded, and the venter isfastigate. The greatest thickness is in theinner third and is between two-thirds andone-half of the whorl height. The costal whorlsection has parallel sides. The ornamentationconsists of very broad, massive, round-

1956 479


crested ribs which begin just above theumbilical shoulder; they are directed radiallyand are somewhat attenuated on the middleof the sides. At the ventrolateral shoulders,each rib develops into a large swelling whichis slightly turned forward.REMARKS: Tissotia halli is similar in su-

ture and ornamentation to T. regularis Hyatt(1903, p. 53), but the latter has a distinctlybiconvex whorl section.

Tissotia waltheri and T. singewaldi (Knech-tel, 1947, in Knechtel, Richards, and Rath-bun) resemble T. halli in whorl section,suture, and pattern of ornamentation but arecharacterized by a more pronounced tuber-culation.OCCURRENCE: Tissotia halli occurs in the

Celendin formation (Lenticeras baltai zone),in bed 3 of the Santa Clara section, togetherwith Lenticeras lissoni and Texanites sp.

Tissotia foumeli (Bayle)Plate 62, figures 3-4

Ammonitesfourneli BAYLE, 1849, p. 360, p1. 17,figs. 3-4.

B-uchiceras fourneii; BAYLE, 1878, p1. 40, fig. 3.Buchiceras Fourneli Bayle; PERON, 1889 (1889-

1890), p. 9, p1. 15, figs. 10-14.Tissotia Fourneli Bayle sp. emend. Peron; DE

GROSSOUVRE, 1893, p. 36, fig. 18.Tissotia Fourneli Bayle emend. Thomas et

Peron; PERON, 1897 (1896-1897), p. 59, p1. 10,figs. 1-8, pl. 11, figs. 9-10.

Metatissotia fourneli (Bayle); HYATT, 1903, p.45.

Tissotia fourneli (Bayle) Thomas et Peron;NEUMANN, 1907, p. 123, pl. 5, figs. 4-4a.

Tissotia cf. fourneli Bayle; BRUGGEN, 1910, p.724, text fig. 4.

Tissotia singewaldi KNECHTEL, 1947, in Knech-tel, Richards, and Rathbun, p. 114, pl. 34, figs.3a-b.

Tissotia waltheri KNECETEL, 1947, in Knechtel,Richards, and Rathbun, p. 115, pl. 18, figs. 3-4.A single, well-preserved steinkern

(A.M.N.H. No. 27892) is referred to thisspecies; the outer half whorl belongs to thebody chamber.

MEASUEIdENTSA.M-WH. No.

27892D H D/H T D/T U D/U38 20 .53 14 .37 6 .16

DEscRIPTION: The conch is small, lentic-ular, narrowly umbilicated. The intercostal

whorl section is a high, compressed, lanceo-late ogive with indistinct umbilical wall. Thesides are convex, slightly inflated, with amaximum convexity in the inner half, andconverge towards the sharp, fastigate venter,provided with a low carina. The greatestwhorl thickness is just above the umbilicalshoulder and is about two-thirds of the whorlheight. The costal whorl section has lessconvergent sides and distinct ventrolateralshoulders. Just above the umbilical shoulderof the outer whorl, there are seven radiallyelongated tubercles which are the startingpoints of one or two broad, low, slightlyprorsiradiate ribs. They become attenuatedabout the middle of the sides but gainprominence in the outer third and end at theventrolateral shoulder in blunt swellings;there are 20 swellings in the outer whorl,

tFIG. 56. Tissotia fourneli (Bayle). Suture line

of specimen A.M.N.H. No. 27892; XI.

and they are slightly turned and projectedforward. Between the ventrolateral tuberclesand the carina, the venter is slightly concave.The suture (fig. 56) has three low and broadsaddles, the first saddle has a median notch;the others are rounded and entire. The lobesare broad, low, and denticulated.REMARKS: Specimen A.M.N.H. No. 27892

(pl. 62, figs. 3-4) agrees perfectly with thespecimen illustrated by Peron [1897 (1896-1897), p. 59, pl. 10, figs. 1-8] from the baseof the Algerian Senonian. The specimensdescribed by Knechtel as T. singewaldi andT. walthern may perhaps be distinguishedfrom T. fourneli by their pointed tubercles,but, again, Knechtel admits considerablevariation in the strength of the ornamenta-tion.OCCURRENCE: Tissotia fourneli is found in

the Celendlnformation (Lenticerasbaltaizone),in bed 72 of the Celendin section (A.M.N.H.No. 27892), together with T. steinmanni, Tex-anites hourcqi, and Lenticeras baltai. Neu-mann described one specimen from near Cer-ro de Pasco, and Briiggen reports another onefrom La Quinua, Celendin, a location whichis probably the same as that of the specimendescribed here.

480 VOL. 108


Tissotia hedbergi,1 new speciesPlate 63, figures 1-5

Three well-preserved steinkerns, includingtwo almost entire discs, are the available rep-resentatives of this species.

MEASUREMENTS

A.M.NJH. Nos. D H D/H T27893:3 41 25 .61 1327893:2 44.5 25.5 .57 12.527893:1 61.5 37 .60 18

D/T U.32 2.28 3.5.29 2.5

D/U.05.08.04

DESCRIPTION: The conch is small, lentic-ular, platy, very narrowly umbilicated. Thewhorl section is a very high and compressed,lanceolate ogive with narrow and steep um-

A _ t

B

c-FIG. 57. Tissotia hedbergi, new species. A, B, C.

Suture lines of specimens A.M.N.H. Nos. 27893:2,27893: 3, and 27893: 1 (holotype); X 1.

bilical wall and rounded umbilical shoulder.The sides are gently convex, decreasing inconvexity, and converging towards thesharp, fastigate venter. The ornamentationconsists of five to seven very low, broad,and faint, fold-like ribs which begin at theumbilical shoulder, where they are most con-spicuous; they flatten out at about the middleof the sides and become very attenuatedagain in the outer third. The suture (fig. 57)has five broad and rounded saddles; the firstsaddle has a deep median lobule; the othersare rounded and entire. The lobes areminutely denticulated.REMARKS: Tissotia hedbergi is similar in

shape and suture to T. serrata Hyatt (1903,p. 51), but the latter has stronger ornamenta-tion and fine ribs which fork at about the

I This species is named after Dr. Hollis D. Hedberg,whose lucid writings have greatly aided the understand-ing of South American stratigraphy.

middle of the sides. Tissotia regularis (Hyatt,1903, p. 53) and T. fourneli are similar in su-ture and pattern of ornamentation to T.hedbergi, but they have more inflated whorls,much stronger ornamentation, and verydistinct ventrolateral shoulders. Tissotiasteinmanni is a larger species without ventro-lateral shoulders or ornamentation of anykind.OCCURRENCE: Tissotia hedbergi is found in

the Celendin formation (Buchiceras bilo-batum zone), in bed 69 of the Celendin sec-tion, associated with Barroisiceras (Barroisi-ceras) kayi, B. (Solgerites) brancoi, Heterotis-sotia lissoni, H. bucheri, and Buchiceras bilo-batum.

BUCHICERAS HYATT, 1875Buchiceras bilobatum Hyatt

Plate 59, figures 1-2; plate 60, figures 1-6Buchiceras bilobatum HYATT, 1875, p. 370.Buchiceras syriaciforme HYATT, 1875, p. 371.Buchiceras attenuatum HYATT, 1875, p. 372.Buchiceras bilobatum Hyatt; HYATT, 1903, p.

27, pl. 1, figs. 49.Roemeroceras syriaciforme Hyatt; HYATT, 1903,

p. 31, p1. 1, figs. 10-14.Roemeroceras attenuatum Hyatt; HYATT, 1903,

p. 33, pl. 1, fig. 15.Roemeroceras subplanum HYATT, 1903, p. 34,

pl. 2, figs. 4-6.Roemeroceras subplanum Hyatt; Liss6x, 1908,

p. 7, pls. 7, 7a.Buchiceras bilobatum Hyatt; BRtGGEN, 1910,

p. 727, pl. 28, figs. 1-2.Buchiceras bilobatum Hyatt; LtTHt, 1918, p.

81, pl. 1, fig. 1.Barroisiceras grossouvrei KNECHTEL, 1947, in

Knechtel, Richards, and Rathbun, p. 122, pl. 34.Buchiceras bilobatum Hyatt emend. Briiggen;

KNECHTEL, 1947, in Knechtel, Richards, andRathbun, p. 123, pl. 42.

Forty-three specimens, most of themsteinkerns, are assigned to this species. Noneof the specimens is larger than 100 mm. indiameter.

MEEASUIREMENTS

A.M.NX.NOS.

27894:127894:227894:327894:427894:527894:6

D H D/H T D/T U D/U3336.539404748

161818.52523.524

.48

.49

.47

.51

.50

.50

152018.5252223

.45

.55

.47

.51

.47

.48

7910.5101011

.21

.25

.27

.20

.21

.23

1956 481


A.M.N.H. D

Nos.27894:7 52.527894:8 55.527894:9 6227894:10 6327894:11 63.527894:12 6627894/1:1 70.527893:13 73.527894/2:1 7627894:14 81.527894:15. 81.527894: 16 81.527894/2:2 8527894:17 8727894:18 *8827894:19 8927894/2:3 9227894:20 97

H26.527.52930.5303134.533.53541404143404341.545.545

D/H.50.50.47.48.47.47.49.45.46.50.49.50

.51

.46

.49

.47

.50

.46

T28272628322732313238.533.533.537.536.54042

3441

D/T.53.49.42.44.50.41.45.42.42.47.41.44.44

.42

.45

.47

.37

.41

U

10131S1415.51713.519181817.5151820.517213024

D/U.19.23.24.22.24.26.19.26.24.22.21.18.21.24.19.24.22.25

DEscRiniON: The conch is discoidal,stout, narrowly umbilicated. The whorl sec-tion is subquadrate, with very high andperpendicular umbilical wall and roundedumbilical shoulder. The sides are flattened orslightly convex; rarely they may be slightlyconcave. The ventrolateral shoulders aredistinct and vary from angular to broadlyrounded. The venter is broad and varies frombroadly convex to subconvex and even flat.Most of the small specimens have a roof-shaped venter with a very faint siphonalcarina. Although the whorl height is re-

markably constant (about one-half of thediameter) the whorl thickness is very vari-able. It is just above the umbilical shoulderand usually is about four-fifths of the whorlheight, but it may even be slightly larger.Just above the umbilical shoulder, there are

seven or eight, exceptionally six, strong,blunt tubercles which are slightly elongatedradially. On the ventrolateral shoulders thereis a second row of 14 or 15, exceptionally 13,spirally elongated tubercles. Faint, low, fold-like ribs connect the two rows of tubercles;some of the ribs are intercalated or forked.In those forms that tend to have angularventrolateral shoulders and flat venters,

both the umbilical and the ventrolateraltubercles become high, conical, or even

spinose, and the ribs become prominent. Onthe other hand, in those forms with roundedventrolateral shoulders and broadly convex

venter, the tubercles, particularly the ventro-

lateral ones, become very faint. The suture is

composed of three broad, quadrate saddleson the sides, a fourth saddle on the umbilical

wall, two lateral lobes on the sides, and athird lobe in the umbilical wall. There isgreat variation as to the suture details,irrespective of other variants. The saddleshave a distinct median notch, and themargins usually are rounded and entire butcan also be denticulated. The lobes are nar-rower, denticulated, and usually have abifid appearance. Denticulation can affectboth saddles and lobes, giving to the suture afrilled appearance.REMARBS: In spite of the great variation

in whorl thickness, strength of the ornamen-tation, and frilling of the suture, this speciesoffers remarkable constancy in whorl height,in the number of umbilical (seven or eight)and ventrolateral (14 or 15) tubercles, and inthe basic suture pattern. Minute differencesin the details of the suture led Hyatt (1903),working on a few fragmentary specimens, toerect five species and two genera: Buchicerasand Roemeroceras. Liss6n (1908, p. 7) hintedthat all of Hyatt's species may be onlyvariations of a single one. Later, Bruiggenand Liithy, who had large samples at theirdisposal, recognized the untenability ofHyatt's species. Briiggen distinguished thoseforms with rounded venter and attenuatedtuberculation under the name of Buchicerasbilobatum Hyatt var. laeve, which he thoughtwas the same as Buchiceras gabbi Hyatt. Theholotype of the latter species, restudied byLisson (1925, p. 23, pl. 1), has 14 umbilicaltubercles and strong ribs, thus departingradically from Buchiceras bilobatum whichhas only seven to eight umbilical tubercles.

Buchiceras bilobatum is similar in whorlsection and pattern* of ornamentation toTissotia tunisiensis Hyatt (Pervinquiere,1907, pl. 26, figs. la-b, 2a-b, 3a-b, 4a-c). Thelatter has a very conspicuous carina that inlater stages dissolves into siphonal tuberclesand has a larger number of ventrolateraltubercles which persist into maturity, where-as the umbilical tubercles vanish. The pres-ent writer studied the fragmentary specimendescribed by Knechtel (1947, in Knechtel,Richards, and Rathbun) as Barroisiceras gros-souvrei; it is a specimen of Buchiceras bilo-batum with suture of the frilled type and witha slightly roof-shaped venter, which is com-mon in specimens of B. bilobatum of small size.Some species belonging to the genera Diazi-

ceras and Barroisiceras approach B. bilobatum

VOL. 108482


in whorl section and ornamentation, buttheir sutures are not ceratitic as in the latterspecies.OCCURRENCE: Buchiceras bilobatum is the

most common ammonite in the Celendinformation (B. bilobatum zone), in bed 69 ofthe Celendin section (A.M.N.H. No. 27894),in bed 15 of the Bambamarca section(A.M.N.H. No. 27894/2), in bed 154 of theCajamarca section (A.M.N.H. No. 27894/1),and in bed 75 of the Polloc section (A.M.N.H.No. 27894/3).

HETEROTISSOTIA PERON, 1897Heterotissotia peroni Lisson

Plate 64, figures 1-6Heterotissotia neoceratites Peron; LIssON, 1908,

p. 10, p1. 10.Heterotissotia peroni LIss6N, 1908, p. 11, pl.

11.Heterotissotia semmamensis Pervinqui6re; Lis-

SON, 1908, P. 12, pl. 12.Heterotissotia neoceratites Peron; STEINMANN,

1909, p. 5. text figs. 1, 4, 5, 6A-C, 8, 9.Heterotissotia neoceratites Peron; BRUdGGEN,

1910, p. 727.Heterotissotia neoceratites Per.; LUTHY, 1918, p.

51, pl. 4, figs. 3-5, pl. 5, fig. 3.Heterotissotia liss6ni KNECHTEL, 1947, in Knech-

tel, Richards, and Rathbun, p. 121, pl. 34, figs.2a-b.

Barroisiceras brilggeni KNECETEL, 1947, inKnechtel, Richards, and Rathbun, p. 123, pl. 41,figs. 2-4.

Thirty-one steinkerns, including six en-tire discs, are assigned to this species. Thelargest available specimen is a whorl frag-ment of an individual at least 150 mm. indiameter. /

A.M.N.H. Nos.27895:127895:127895/227895/3

MEASUREXENSD H D/H T D/T U59 32 .54 14 .24 773 40 .55 28 .38 775 38 .51 28 .37 1282 46 .52 23 .28 12.5

D/U.12.09.13.15

DESCRIPTION: The conch is discoidal,platy, very narrowly umbilicated. The whorlsection is very high and compressed, withnarrow and steep umbilical wall and broadlyrounded umbilical shoulder. The sides are

convex in the inner half but diminish in con-

vexity and may become slightly concave in

the outer one. The ventrolateral shoulder is

angular, and the venter is flat or subconcave,

provided in the early stages with a faint, lowcarina which is like a raised line betweentwo subconcave bands and which disappears,in most cases, before a radius of 30 mm. Thegreatest whorl thickness is at the end of theinner third and varies between two-thirds andone-third of the whorl height. The umbilicalshoulder has about six strong, hemispherical,blunt tubercles which tend to disappearquickly at about a radius of 30 mm. Theventrolateral shoulder has another row ofabout 22 lateral, spirally elongated tubercleswhich also tend to vanish at a radius of 30

A

B

C

FIG. 58. Heterotissotia peroni Liss6n. A, B, C.Suture lines of specimens A.M.N.H. Nos. 27895/2,27895/1:2, and 27895:2; XI.

mm., but which may exceptionally be pre-served at a radius of 40 mm. or more (pl.64, fig. 3-4). The sides are smooth; however,a few specimens of small size show low, broad,very faint, fold-like ribs which start at theumbilical shoulder and flatten out at aboutthe middle of the sides. The suture (fig. 58)has four broad and rounded saddles on thesides; the first has a median notch of vari-able depth, and the second and third are

generally entire, although the third may haveone or even three small notches. The lobesare also broad, with finely denticulatedterminlations. The siphonal lobe may beasymmetrical.REMARKS: Liss6n (1908) assigned three

whorl fragments to three different species:H. neoceratites Peron, H. peroni Lisson, andH. semmamensis Pervinquiere, which differfrom one another only in minute suture de-tails. Later, Steinmann (1909) investigated alarge Peruvian sample of the species referred

1956 483


in this paper to H. peroni; he observed thegreat variability of the whorl thickness andof the suture, and attributed it to H. neocera-tifes Peron. He states: "In dem reichlichenMaterial das mir von Het. vorliegt, kann mannach Windungsquerschnitt Skulptur undLobenlinien keine irgendwie gut begrentzenArten unterschieden bezeichnet hat, sinddurch reichliche Zwischenformen mit denschmdleren Semmamensis-Formen Pervin-quieres verkniipft. Ganz unabhangig davonvariiert die Verzierung, indem sie bei neo-ceratites bald friiher, bald spater verschwin-det; bei semmamensis scheint die Skulpturfreilich immer schon fruih zu fehlen. Wollteman aber nach den Loben Arten oderVarietiten unterscheiden, so k6nnte manfast aus jeden Stticke eine Art machen. Ichziehe es daher vor, die Gesamtheit der mirvorliegende Stutcke unter der BezeichnungHet. neoceratities Per. zusammenfassen. Willman die schmalmiindigen und stets friuh alsdritter Name semmamensis Perv. verwendtwerden...." This conclusion is also sup-ported by Liithy (1918). Heterotissotia neo-ceratites is a poorly known North Africanspecies which agrees in whorl section andsuture with H. peroni but can be distin-guished by the fact that, at a diameter of 70mm., it has a well-marked ornamentationconsisting of sigmoidal and bifurcating ribswhich have not been observed in any of thePeruvian specimens of H. peroni. The presentwriter, therefore, considers that they are notconspecific and proposes to use Liss6n's termH. peroni, the earliest specific name appliedto a Peruvian representative of this species.The specimen described by Knechtel (1947,

in Knechtel, Richards, and Rathbun) as -H.lissoni was available to the present writer. Itis a small representative of H. peroni with21 sharp ventrolateral tubercles and a faintcarina, characteristic of the early stages ofthis species. Also, the very poorly preservedspecimen described by the same author asBarroisiceras bruggeni was studied by thewriter. Its general shape, whorl section,ornamentation, and suture are those of H.Peroni. The suture illustrated by Knechtel(1947, in Knechtel, Richards, and Rathbun,text fig. 19) shows indented saddles and lobeswhich the writer could not verify. It appearsinstead that the saddles are rounded andentire, pseudoceratitic-quite different from

the festooned saddles of the genus Barrois-iceras.OCCURRENCE: Heterotissotia peroni is a

common ammonite in the Celendin forma-tion (Buchiceras bilobatum zone), in bed 15 ofthe Bambamarca section (A.M.N.HI. No.27895/1), in bed 69 of the Celendfn section(A.M.N.H. No. 27895/3), in bed 75 of thePolloc section (A.M.N.H. No. 27895/2),and in bed 144 of the Cajamarca section(A.M.N.H. No. 27895). It is associated withB. bilobatum and several species of Tissotiaand Barroisiceras.

Heterotissotia bucheri,l new speciesPlate 65, figures 1-S

Nine well-preserved steinkerns, includingfive entire discs, are available for study. Thelargest specimen is 115 mm. in diameter.Specimen A.M.N.H. No. 27896:5 (pl. 65,figs. 1-2) is the holotype.

MEASREMtENTSA.M.N.H. Nos.

27896:127896:227896/1:127896:327896:427896:527896:6

D737581.582858990

H3836.540.540.5454546

D/H T.52 43.49 40.50 47.49 51.5.53 47.51 41.51 42

D/T U.59 14.53 17.58 18.62.55 16.46 18.47 20

D/U.19.23.22

.19

.20

.22

DESCRIPTION: The conch is discoidal,stout, very narrowly umbilicated. The whorlsection is very high, with high umbilicalwall and broadly rounded umbilical shoulder.The sides are strongly convex and inflatedin the inner half of the sides but decrease inconvexity and become flat to subconcave inthe outer third. The ventrolateral shoulderis angular, and the venter is flat and broad;it bears a median, low but conspicuous carina.The greatest whorl thickness is slightly abovethe umbilical shoulder, and although it isusually slightly larger than the whorl heightit may be also smaller. The whorl height isnoticeably constant-about one half of thediameter. Just above the umbilical shoulder,there is a row of six to seven massive, blunt,radially elongated tubercles which extendtowards the middle of the sides where theyflatten out. Also, along the ventrolateralshoulder, there is a second row of 14 to 15conspicuous, strong, spirally elongated tuber-

' Named in honor of Prof. Walter H. Bucher.

VOL. 108484


cles. Rarely, fold-like ribs connect the tworows of tubercles. The ornamentation tendsto be obliterated in the body chamber. Thesuture has three, rarely four, very broad andlow saddles; the first saddle has one to threenotches; all the others are rounded and en-tire, although the second and third saddlesmay, exceptionally, have a small notch.The lobes have parallel sides and finely dentic-ulated terminations.

REMARKS: Heterotissotia bucheri is similarto H. peroni in suture, general shape, patternof ornamentation, and in possessing a lowsiphonal carina, but it can be easily distin-guished by its thicker and inflated whorlsection, its smaller number of ventrolateraltubercles, and by the persistence of the carinaand tuberculation into maturity. Heterotisso-tia bucheri resembles Buchiceras bilobatumin the stoutness of the whorl section, andin the presence of umbilical and ventro-lateral tubercles in almost similar numbersand strength but is distinguishable by themore pronounced carina, the bulging sides,and, most important, by the fact that thesaddles are usually rounded and entire, whilein Buchiceras bilobatum they have at leastone median notch.

OCCURRENCE: Heterotissotia bucheri is avery common ammonite in the Celendinformation (Buchiceras bilobatum zone), inbed 69 of the Celendin section (A.M.N.H.No. 27896), in bed 144 of the Cajamarcasection (A.M.N.H. No. 27896/1), and in bed75 of the Polloc section (A.M.N.H. No.27896/2). It is associated with H. peroni,Buchiceras bilobatum, Barroisiceras (Barro-isiceras) haberfellneri, B. (B.) kayi, Barroisi-ceras (Solgerites) brancoi, Barroisiceras (For-resterid) basseae, B. (F.) alluaudi, and Tissotialhedbergi.

FAMILY LENTICERATIDAE HYATT, 1900LENTICERAS GERHARDT, 1898

Lenticeras baltai Liss6nPlate 66, figures 1-2

Lenticeras baltae Liss6N, 1908, p. 14, pls. 14a,14b.

Lenticeras baltae Liss6n; LIss6N, 1936, p. 53, pls.1-3.

Lenticeras baltae Liss6n; BASSE, 1942, p. 354.Lenticeras baltae Liss6n; KNECHTEL, 1947,

in Knechtel, Richards, and Rathbun, p. 126, pl.37, fig. 1, pl. 44.

Lenticeras baltai; RIVERA, 1949, p. 32, p1. 7,fig. 1, pI. 8, fig. 1.A single steinkern, A.M.N.H. No. 27897, is

available.

A.M.N.H. No.2707

MEASUREMNTSD H D/H T D/T U D/T140 71 .51 45 .32 - -

DESCRIPTION: The conch is large, lentic-ular, stout, very narrowly umbilicated. Thewhorl section is a very high, lanceolate ogivewith steep and high umbilical wall androunded umbilical shoulder. The sides arearched, with the greatest convexity in theinner third, and converge evenly towards thefastigate venter. The greatest thickness is inthe inner third and is between three-fourthsand two-thirds of the whorl height.

Specimen A.M.N.H. No. 27897 has smoothsides. (Lisson's holotype is a somewhatweathered steinkern, and he suggested thatthe ornamentation, if any, may have beeneroded away.)The suture has four broad, low, and rounded

saddles; the first saddle is deeply divided inthree parts, whereas the others are almostentire, with one or more indentations andwith very peculiar rounded endings. Thelobes are slightly strangulated and digitated.REMARKS: Lenticeras gerhardti Knechtel is

similar to L. baltai in size, shape, whorl sec-tion, and suture, and was differentiated onlyby its very faint ornamentation. The writerexamined the holotype of L. gerhardti andfinds that the ribs are very inconspicuous.Lenticeras andii Gabb (Lisson, 1908, p. 13)has a thicker whorl section and stronger ribsthan L. baltai.OCCURRENCE: Lenticeras baltai occurs in

the Celendin formation (Lenticeras baltaizone), in bed 72 of the Celendmn section,associated with Texanites hourcqi, Desmo-phyllites gaudama, Tissotia steinmanni, andT. fourneli. Lisson's holotype is from Ha-cienda Quilca, Provincia Pomabamba, Mara-no6n River. Rivera (1949) reports it fromRio Pachitea (Huanuco) and Pongo de Ren-tema (Jaen).

Lenticeras lissoni KnechtelPlate 66, figures 3-4

Lenticeras lissoni KNECHTEL, 1947, in Knechtel,Richards, and Rathbun, p. 127, pl. 46, figs. 1-2.

1956 485


One poorly preserved steinkern representsthis species. The present writer has examinedthe holotype.

MEASM3EENTSA.M.N.H. No.

27898Knechtel's

holotype

D H D/H T D/T UD/U132 78 .59 57 .43

143 78 .59 66 .49- -

DESCRIPTION: Lenticeras lissoni is veryclosely related to L. baltasi; they have thesame suture, general shape, and whorl sec-tion and differ only in that L. lissoni has aless compressed whorl section, its greatestthickness being about five-sixths of the whorlheight, while in L. baltai the greatest thick-ness is between two-thirds and three-fourthsof the whorl height. Specimen A.M.N.H.No. 27898 is slightly less compressed thanthe holotype and therefore is closer to L.baltai.Both specimen A.M.N.H. No 27898 and

the holotype have very faint, wavy ribs onthe sides; they are not, however, so distinctas those of the more compressed L. andii.REMARKS: Lenticeras baltai, L. lissoni, and

L. acndii form a closely related group,differing from one another mainly in theproportions of the whorl height to the thick-ness and in the more pronounced ornamenta-tion of the depressed forms. Lenticeras baltaiis the most compressed form and has smoothsides; L. andii is a depressed form with pro-nounced ribs; and L. lissoni occupies an inter-mediate position, with slightly compressedwhorls and faint ornamentation. These threespecies may not be easily separated if more

extensive and significant collections are

gathered. It may be a case similar to that ofB2uchiceras bilobatum or that of Heterotissotiaperoni, species which are characterized by thegreat variation of the whorl section and bythe increase in the strength of the ornamen-

tation in those individuals with thicker whorls.OCCURRENCE: Lenticeras lissoni is found in

the Celendin formation (Lenticeras baltaizone), in bed 3 of the Santa Clara section,associated with Texanites sp., Desmophyllitesgaudama, and Tissotia halli. Lenticeras gabbi,also a Peruvian form, was found first in Pataz(La Libertad) and later in Venezuela (Ger-hardt, 1897a, p. 81) where it is associatedwith T. texanum, T. can-aense, Gauthiericeras

lenti, Gauthiericeras margae, and Amaitheussieversi.

INCERTAE SEDISNEOLOBITES FISCEER, 1882

Neolobites kummeli,l new speciesPlate 66, figures 5-6

Neolobites cf. peroni Hyatt; SCHLAGINTWEIT,1912, p. 100, text fig. 4.

Neolobites cf. Vibrayeanus d'Orb.; BOIT, 1926,p. 40.

Fourteen specimens, all somewhat dis-torted steinkerns, are at hand. Only onespecimen, 100 mm. in diameter, is a completedisc. Specimen A.M.N.H. No. 27899:1is the holotype.

DESCRIPTION: The conch is discoidal,platy, very narrowly umbilicated. The whorlsection is very high and compressed, withvery low umbilical wall and indistinct um-bilical shoulder. The sides are evenly andgently arched, converging towards the nar-row, truncated, flat venter. The ventrolateralshoulder is angular and sharply distinct.The greatest whorl thickness is slightly be-low the middle of the sides and is less thanone-third of the whorl height. It has numer-ous small, closely set, spirally elongatedtubercles along the ventrolateral shoulders.Only one specimen (pl. 66, fig. 6) has veryfaint, radial, low, fold-like ribs which startin the umbilical shoulder and flatten outat the end of the inner third. All the otherspecimens have smooth sides. The suture isthe same as that of N. vibrayeanus, withentire lobes and saddles.REMARKS: Neolobites kummeli is similar to

N. vibrayeanus d'Orbigny in size, shape,whorl section, and suture but is distinguish-able by the lack of the flexuous ribs whichornament the latter species and which maybe very strong, as in the specimens illus-trated by Choffat [1898 (1886, 1898)]. Neo-lobites peroni Hyatt (=N. vibrayeanus d'Or-bigny; Peron [1890 (1889-1890)], pl. 18,figs. 1-2) is an inflated form with low, mas-sive umbilical tubercles and attenuatedfalciform ribs. Neolobites kummeli is similarin shape, suture, lack of strong ribs, andwhorl section to N. isidis Greco (1915, p.

1 Named in honor of Prof. Bernhard Kummel.

486 VOL. 108


206) which is characterized by its carinateventrolateral shoulders. Neolobites bassleriBoit (1926) another Peruvian species, lacks,according to the description, ornamentationand, unlike any other Neolobites, has a

divided third lateral lobe.

OccuRRENcE: Neolobites kummeli is foundin the Romir6n formation, in bed 48 of theCelendfn section (A.M.N.H. No. 27899), to-gether with Acanthoceras chasca, A. polio-cense, A. sangalense, Forbesiceras sp., andLissoniceras mermeti.

1956 487

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490 VOL. 108


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RIVERA, ROSALVINA1949. F6siles sen6nicos del Pongo de Rentema.

Volumen Jubilar del 25 Aniversario,Sociedad Geologica del Per6i, parte 2.Lima, fasc. 17, pp. 1-35, pls. 1-10.

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SCELAGINTWEIT, 0.1912. Die Fauna des Vracon und Cenoman in

Per('. Neues Jahrb. f. Min. Geol.

1956 4.91

BULLETIN AMERICAN MUSEUM OF NATURAL HISTORYPalaeont., suppl. vol. 33, pp. 43-135,pls. 5-7.

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1881. Ueber Tithon und Kreide in den peru-anischen Anden. Neues Jahrb. f. Min.Geol. u. Palaeont., yr. 1881, vol. 2,pp. 130-153, pls. 6-8.1882. VJber Jura und Kreide in den Anden.Ibid., yr. 1882, vol. 1, pp. 166-170.1909. Probleme der Ammoniten-Phylogenie(Gattung-Heterotissolia). Sitzber. Nied-errheinischen Gesell. Nat. u. Heilk.Bonn, pp. 1-16.1929. Geologie von Peru. Heidelberg, CarlWinters Universitatsbuchhandlung, 448pp-1930. Geologia del Peru. Heidelberg, CarlWinters Universitatsbuchhandlung, 448PP.STIELER, CARL

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492 VO0L. 108


The fossil Cephalopoda of the Cretace-ous rocks of southern India. Mem. Geol.Surv. India, Paleont. Indica, [sers. 1,3, vol. 1], pp. 41-216, pls. 26-94.

TAFUR, ISAAC1950. Nota preliminar de la geologia del valle

de Cajamarca, Peru. Lima, UniversidadNacional de San Marcos, 56 pp.

WASSON, THERON, AND J. H. SINCLAIR1927. Geological explorations east of the

Andes in Ecuador. Bull. Amer. Assoc.Petrol. Geol., vol. 11, pp. 1253-1281,pls. 9-13.

WEAVER, C. E.1942. A general summary of the Mesozoic

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WEEKS, L. C.1947. Paleogeography of South America. Bull.

Amer. Assoc. Petrol. Geol., vol. 31, pp.1194-1241.

WELTER, 0. A.1913. Eine Tithonfauna aus Nord-Peru. Neues

Jahrb. f. Min. Geol. u. Palaeont., yr.

1913, vol. 1, pp. 28-42, pl. 5.WRIGHT, C. W., AND E. V. WRIGHT

1951. A survey of the fossil Cephalopoda ofthe Chalk of Great Britain. London,the Palaeontographical Society, vol. for1950, pp. 1-40.

YABE, H.

1904. Cretaceous Cephalopoda from the Hok-kaido, pt. 2. Jour. College Sci. Imp.Univ. Tokyo, Japan, vol. 20, art. 2,pp. 1-45, pls. 1-6.

1956 493

PLATES 31-66

PLATE 311. Goyllarisquisga formation (KG) overlying the Trisasic Uliachin (TU), and the

Paleozoic Mitu (PM) formations. North side of the Crisnejas River just west of itsjunction with the Maraff6n River.

2. Chimni sandstone (KCh) overlying the upper Jurassic "Chicama beds" (JCh).South side of the Chicama River, 250 meters downstream from Baflos de Chim(i, typelocality of the Chim(i sandstone.

,ETIN AMER. Mus. NAT. HIST.

tV*

, ,

.,*4 .

"vi. .fr 4,

I--iV-

:. .7

I. t. 4#

2

'VOL. 108, PLATE 31

I

BULLETIN AMER. Mus. NAT. HIST.

..

S-

- k tAS'7

-.

2

VOL. 108, PLATE

PLATE 321. Santa formation (KS) overlying Chim1i'sandstone (KCh). El Cepo anticline, north

of Hacienda Farrat.2. Type section of the Santa (KS) and Carhuaz (KCa) formations overlying Chimtf

sandstone (KCh). Cerro Huallhua, west side of the Santa River, northwest of Carhuaz.

PLATE 331. Chimfi sandstone; the jacob staff (1.50 meters long) lies on a bedding plane. San

Jorge River, upper Chicama Valley.2. Type section of the Inca formation (KI), overlying Goyllarisquisga formation

(KG) and underlying Chulec formation (KChu); Cajamarca section, 1 kilometer northof Bafios del Inca, Cajamarca.

EN AMER. Mus. NAT. HIST.

ii; L J.

'I

2

VOL. 108, PLATE33

-"' I

"IV, ..,

L.,I

KC:

4F

-:,.'0,0.

1.4NW'

BULLETI1, AMER. Mus. NAT. HIST.

2

;-.1'

PLATE 341. Sandstone of the Goyllarisquisga formation. Cajamarca section, Cerro Abil6n, east

of Bafios del Inca, Cajamarca.2. Typical cross-bedded sandstone of the Goyllarisquisga formation. Same locality

as above figure.

PLATE 351. Platy, black, strongly bituminous limestone of the Pariatambo formation. Hualga-

yoc section, 2 kilometers east of Hualgayoc.2. Discoidal, bituminous limestone concretions in bituminous marl of the Pariatambo

formation. The fossils belong to Oxytropidoceras carbonarium Gabb; the ruler is 10 centi-meters long. Pariahuanca section. Pariahuanca, Callej6n de Huaylas.

fLETIN AMER. Mus. NAT. HIST.

2

VOL. 108, PLATE 35

I

BULLETIN AMER. Mus. NAT. HIST. VOL. 108, PLATE 3I'7i

N

PLATE 361. Sangal syncline; automobile road from Cajamarca to Celendin, just south of

Encafiada. Mujarr1in formation (KM), Romir6n (KR), Cofior (KCo) and Cajamarca(KCa) formations.

2. View northeast. The Cajamarca section. Carhuaz (KC), Goyllarisquisga (KG),Inca (KI), Chulec (KChu), Pariatambo (KP), Yumagual (KY), Mujarrin (KM),Cajamarca (KCa) and Celendin (KCe) formations.

PLATE 371. Typical wavy-bedded, nodular limestone of the Yumagual formation. Chicama

section, north of Hacienda Huaycot, upper Chicama Valley.2. Section near Puerto Nuevo, Yanacanchilla, east of Hualgayoc, Mujarr(in formation

(KM), Quillquiiian group (KQ), and Cajamarca formation (KCa).


2

PLATE 381. Exposures of the Cajamarca formation (KCa) overlain by Chota formation (KCho),

along the Chotano River, north of Lajas, Lajas section.2. Red-bed shale and sandstone of the Chota formation in El Ahijadero, west of

Hacienda Santa Clara. In the background, limestones of the Cajamarca formation(KCa) thrust over the Chota formation.

PLATE 391. Sandstone of the Rosa formation (KRo) disconformably overlying channeled

Crisnejas formation (KCr). Type section of the Crisnejas and Rosa formations. Southside of the Crisnejas River, near Santa Rosa.

2. Quartz pebble conglomerate of the Rosa formation. Type section of the Rosa for-mation. Locality same as 1.

LETIN AMER. Mus. NAT. HIST.

b -

2

VOL. 108, PLATE 39

I


I I

PLATE 401-3. Lissoniceras mermeti (Coquand). 1, 2. A.M.N.H. No. 27381/1 :1, lateral and ven-

tral views, X1. 3. A.M.N.H. No. 27381/1:2, frontal view, X1.4, 5. Protanisoceras blancheti (Pictet and Campiche), A.M.N.H. No. 27832, lateral

and ventral views, X 1.6, 7. Bostrychoceras? sp. indet., A.M.N.H. No. 27835, lateral and basal views, XI.8, 9. Paraturrilites lewesiensis (Spath). 8. A.M.N.H. No. 27833:1, lateral view, X1.

9. A.M.N.H., No. 27833:2, lateral view, XI.10-12. Valanginites broggii (Liss6n), A.M.N.H. No. 27836:1, lateral, ventral, and

frontal views, X 1.

PLATE 411, 2. Desmoceras latidorsatum (Michelin), A.M.N.H. No. 27387, lateral and ventral

views, X2.3, 4. Desmophyllites gaudama (Forbes), A.M.N.H. No. 27389, lateral and frontal

views, X1.5-8. Desmoceras chimuense, new species. 5, 6. A.M.N.H. No. 27388:2, lateral and

ventral views, XI. 7, 8. A.M.N.H. No. 27388:1, holotype, lateral and ventral views,X1.

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VOL. 108, PLATE 41


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VOL. 108, PLATIE 4

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8

PLATE 421-8. Parahoplites quilla, new species. 1-3. A.M.N.H. No. 27391 :1, holotype, frontal,

ventral, and lateral views, X1. 4-6. A.M.N.H. No. 27391: 2, frontal, ventral, and lateralviews, XI. 7, 8. A.M.N.H. No. 27391:3, lateral and ventral views, X1.

9, 10. Parahoplites inti, new species, holotype, A.M.N.H. No. 27392, lateral andventral views, X 1.

11, 12. Parahoplites nicholsoni, new species, holotype, A.M.N.H. No. 27390:1, lateraland ventral views, X1.

PLATE 431-4. Douvilleiceras monile (Sowerby). 1, 2. Lateral and ventral views of inner whorls

of specimen A.M.N.H. No. 27393, X2. 3, 4. Lateral and ventral views of specimenA.M.N.H. No. 27393, Xl.

5-10. Parengonoceras tetranodosum (Liss6n). 5, 6. A.M.N.H. No. 27398, lateral andventral views, XI. 7, 8. A.M.N.H. No. 27398:2, lateral and ventral views, XI. 9, 10.A.M.N.H. No. 27398:1, lateral and ventral views, XI.

11, 12. Engonoceras sp. indet., A.M.N.H. No. 27395, lateral and ventral views, X 1/2.

VOL. 108, PLATE 43

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PLATE 441. Parengonoceras tetranodosum (Liss6n), A.M.N.H. No. 27398:3, lateral view, Xl.2. Parengonoceras guadaloupaeforme (Sommermeier), A.M.N.H. No. 27397, lateral

view, X1.3, 4. Parengonoceras pernodosum (Sommermeier), A.M.N.H. No. 27396/1:1, lateral

and frontal views, XI.

PLATE 451-5. Parengonoceras pernodosum (Sommermeier). 1, 2. A.M.N.H. No. 27396, lateral

and ventral views, XI. 3-5. A.M.N.H. No. 27396:2, lateral, ventral, and frontal views,Xi.

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PLATE 461-6. Parengonoceras haasi, new speces. 1, 2. A.M.N.H. No. 27399:3, lateral and

ventral views, XI. 3, 4. A.M.N.H. No. 27399:2, lateral and frontal views, XI. 5, 6.Holotype, A.M.N.H. No. 27399:1, ventral and lateral views, XI.

7-10. Knemiceras attenuatum (Hyatt). 7, 8. A.M.N.H. No. 27849:1, lateral and ven-tral views, X 1. 9, 10. A.M.N.H. No. 27849/3, lateral and ventral views, X 1.

11, 12. Knemiceras attenuatum spinosum (Sommermeier), A.M.N.H. No. 27850,lateral and frontal views, XI.

PLATE 471, 2. Knemiceras trianguzare, new species, A.M.N.H. No. 27853, holotype, ventral

and lateral views, Xi.3. Knemiceras gabbi Hyatt, A.M.N.H. No. 27852, lateral view, X2/3.4, 5. Knemiceras syriacum (von Buch), A.M.N.H. No. 27851, lateral and ventral views,

X1.

LETIN AMER. Mus. NAT. HIST. VOL. 108, PLATE 47

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PLATE 481-5. Knemiceras raimondii (Liss6n). 1, 2. A.M.N.H. No. 27856:4, lateral and frontal

views, Xl. 3, 4. A.M.N.H. No. 27856:2, lateral and frontal views, XI. 5. A.M.N.H.No. 27856:7, lateral view, XI.

6, 7. Knemiceras raimondii tardum, new subspecies, A.M.N.H. No. 27858, holotype,frontal and lateral -views, XI.

PLATE 491. Knemiceras raimondii pacificum, new subspecies, A.M.N.H. No. 27857, holotype,

lateral view, X1.2-4. Brancoceras aegoceratoides Steinmann. 2. A.M.N.H. No. 27866:1, lateral view,

XI. 3, 4. A.M.N.H. No. 27866:2, lateral and ventral views, XI.5. Oxytropidoceras peruvianum (von Buch), A.M.N.H. No. 27861,, lateral view, XI.6. Oxytropdoceras carbonari-um (Gabb), A.M.N.H. No. 27860, lateral view, XI.

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PLATE 501-4. Prolyelliceras peruviatnum Spath. 1, 2. A.M.N.H. No. 27867:1, ventral and

lateral views, XI. 3. A.M.N.H. No. 27867:3, lateral view, XI. 4. A.M.N.H. No.27867:2, lateral view, X1.

5. ?Knemiceras ollonense (Gabb), A.M.N.H. No. 27855, lateral view, XI.6. Dipoloceras sp. indet.,-A.M.N.H. No. 27865, lateral view, X2/3.

PLATE 511-3. Lyelliceracs Iyelli (Leymerie) d'Orbigny. 1. A.M.N.H. No. 27868:6, lateral view,

X2. 2. A.M.N.H. No. 27868:4, lateral view, X 1. 3. A.M.N.H. No. 27868:2, lateral view,Xi.

4-7. Lyelliceras ulricki Knechtel. 4, 5. A.M.N.H. No. 27870:3, lateral and ventralviews, X1. 6, 7. A.M.N.H. No. 27870:1, lateral and ventral views, X2.

8, 9. Parengonoceras? champaraense, new species, A.M.N.H. No. 27848, holotype,lateral and ventral views, XI.

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PLATE 521, 4. Knemiceras ovale, new species. 1. A.M.N.H. No. 27854:1, lateral view, XI. 4.

A.M.N.H. No. 27854, holotype, lateral view, XI.2. Knemiceras? ziczag Breistroffer, A.M.N.H. No. 27859, lateral view, X1.3. Lyelliceras pseudolyelli Parona and Bonarelli, A.M.N.H. No. 27869:2, lateral view,

X1.

PLATE 531-4. Acanthocerats chasca, new species. 1, 2. A.M.N.H. No. 27872/1, ventral and lateral

views, X1. 3, 4. A.M.N.H. No. 27872, holotype, ventral and lateral views, X1.5. .Venezolkeras venezolanum (Stieler), A.M.N.H. No. 27863, lateral view, X .6. Venezoliceras karrisoni, new species, A.M.N.H. No. 27864, holotype, lateral view,

x1.7-9. Acanthoceras sangatense, new, species. 7, 8. A.M.N.H. No. 27874:1, holotype,

ventral and lateral views, XI. 9. A.M.N.H. No. 27874:2, lateral view, XI.10, 11. Acanthoceras pollocense, new species, A.M.N.H. No. 27873:1, holotype, ven-

tral and lateral views, Xl.

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PLATE 541-4. Pseudoaspidoceras reesidei, new species. 1, 2. A.M.N.H. No. 27876:1, holotype,

lateral and frontal views, XI. 3, 4. A.M.N.H. No. 27876:3, ventral and lateral views,XI.

5, 6. Sharpeiceras occidentaJe, new species, A.M.N.H. 27871, holotype, lateral and ven-tral views, X1.

PLATE 551-4. Broggiiceras olssoni, new species, 1, 2. A.M.N.H. No. 27877:5, holotype, frontal

*and lateral views, XI. 3, 4. A.M.N.H. No. 27877:9, frontal and lateral views, Xl.5-8. Mammites nodosoides afer Pervinqui&re. 5, 6. A.M.N.H. No. 27875/1, lateral

and ventral views, X1. 6, 7. A.M.N.H. No. 27875, ventral and lateral views, Xl.

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PLATE 581-4. Barroisiceras (Solgerites) brancoi (Solger). 1, 2. A.M.N.H. No. 27887/1, lateral

and ventral views, XI. 3, 4. A.M.N.H. No. 27887:1, frontal and lateral views, X1.5. Barroisiceras (Forresteria) basseae, new name, A.M.N.H. No. 27888, lateral view,

X6.6, 7. Texanites hsourcqi Collignon, A.M.N.H. No. 27881, lateral and ventral views, Xl1.

PLATE 591, 2. Buchiceras bilobatum Hyatt, A.M.N.H. No. 27894/2:2, frontal and ventral

views, X1.3, 4. Coilopocerasjenksi, new species, A.M.N.H. No. 27882, holotype, lateral and ven-

tral views, XI.

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VoL. 108, PLATE 60

PLATE 601-6. Buchiceras bilobatum Hyatt. 1, 2. A.M.N.H. No. 27894:9, lateral and ventral

views, XI. 3, 4. A.M.N.H. No. 27894:7, lateral and ventral views, XI. 5, 6. A.M.N.H.No. 27894:21, ventral and lateral views, X1.

7. Coilopoceras jenksi, new species, A.M.N.H. No. 27882/1:1, lateral view, X4/5.

PLATE 611. Barroisiceras (Forresteria) alluaudi Boule, Lemoine, and Th6venin, A.M.N.H. No.

27889, lateral view, XI.2, 3. Tissotia steinmc&nni Liss6n, A.M.N.H. No. 27890, lateral and frontal views, X1.4, 5. Coilopoceras newelli, new species, A.M.N.H. No. 27883:7, holotype, lateral and

frontal views, X1/3.

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BuJLLETIN AmER. Mus. NAT. HIST. VOL. 108, PLATE 62

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PLATE 621, 2. Tissotia halli Knechtel, A.M.N.H. No. 27891 :1, frontal and lateral views, Xi.3, 4. Tissotia fourneli (Bayle), A.M.N.H. No. 27892, ventral and lateral views, XI.5-7. Coilopoceras newelli, new species, A.M.N.H. No. 27883:1, lateral, frontal, and

ventral views, X 1.

PLATE 631-5. Tissotia hedbergi. new species. 1, 2. A.M.N.H. No. 27893:3, frontal and lateral

views, XI. 3, 4. A.M.N.H. No. 27893:2, ventral and lateral views, XI. 5, 6. A.M.N.H.No. 27893:1, holotype, lateral view, Xl.

6-11. Hoplitoides inca, new species. 6. A.M.N.H. No. 27884/1:2, lateral view, XI.7, 8. A.M.N.H. No. 27884:1, holotype, frontal and lateral views, XI. 9-11. A.M.N.H.No. 27884:3, lateral, ventral, and frontal views, XI.

VOL. 108, PLATE 63BULLETIN AMER. Mus. NAT. HIST.

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PLATE 641-6. Heterotissotia peroni Lisso6n. 1, 2. A.M.N.H. No. 27895/2, lateral and ventral

views, XI. 3, 4. A.M.N.H. No. 27895/1:2, lateral and ventral views, XI. 5, 6. A.M.N.H.No. 27895:2, lateral and frontal views XL.

PLATE 65-1-5. Heterotissotia bucheri, new species. 1, 2. A.M.N.H. No. 27896:5, holotype, ven-

tral and lateral views, XI. 3, 4. A.M.N.H. No. 27896:6, frontal and lateral views, XI.5. A.M.N.H. No. 27896:4, lateral view, X1.


3

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PLATE 661, 2. Lenticeras baltai Liss6n, A.M.N.H. No. 27897, lateral and frontal views, XI/2.3, 4. Lenticeras lissoni Knechtel, A.M.N.H. No. 27898, ventral and lateral views,

X1/2.5, 6. Neolobites kummeli, new species. S. A.M.N.H. No. 27899:1, holotype, lateral

view, XI. 6. A.M.N.H. No. 27899:2, lateral view, Xl.

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