Linking cultural and environmental change in Peruvian ......Linking cultural and environmental...

Catena 78 (2009) 234–249

Contents lists available at ScienceDirect

Catena

j ourna l homepage: www.e lsev ie r.com/ locate /catena

Linking cultural and environmental change in Peruvian prehistory:Geomorphological survey of the Samaca Basin, Lower Ica Valley, Peru

David Beresford-Jones a,⁎, Helen Lewis b,1, Steve Boreham c,2

a Department of Archaeology, University of Cambridge, Downing Street, Cambridge, CB2 3DZ, UKb School of Archaeology, University College Dublin, Newman Building, UCD Belfield, Dublin 4, Irelandc Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, UK

⁎ Corresponding author. Fax: +44 1223 333503.E-mail addresses: [email protected] (D. Beresford-Jo

(H. Lewis), [email protected] (S. Boreham).1 Fax: +353 1 716 1184.2 Fax: +44 1223 333392.

0341-8162/$ – see front matter © 2008 Elsevier B.V. Adoi:10.1016/j.catena.2008.12.010

a b s t r a c t
a r t i c l e i n f o
Article history:

The lower Ica Valley on th

Received 25 September 2007Received in revised form 23 October 2008Accepted 19 December 2008

Keywords:South coast PeruDesertPalaeoenvironmentArchaeologyRiparian dry-forestProsopis

e hyperarid south coast of Peru is today largely depopulated and bereft ofcultivation. Yet its extensive archaeological remains attest to substantial pre-Hispanic populations. Weprovide a case-study of Pre-Hispanic culturally induced environmental change through combining fieldarchaeological and geomorphological survey with archaeobotanical, sedimentary and soil micromorphologyapproaches. Our investigations reveal that, although major El Niño climatic perturbations occurring aroundthe end of the Early Intermediate Period are part of the explanation, more gradual, human-induced reductionin riparian dry-forest vegetation also lie behind major landscape change, which culminated during theMiddle Horizon.

© 2008 Elsevier B.V. All rights reserved.

1. Introduction and area of study

The lower Ica Valley on the south coast of Peru is today largelydepopulated and bereft of cultivation. Yet its extensive archaeologicalremains attest to substantial pre-Hispanic populations and present aprima facie case for changed ecological and landscape conditions.This paper describes geomorphological survey conducted in theSamaca Basin, as part of an archaeological investigation exploringthis landscape change.

The Peruvian south coast is one of the oldest and driest deserts inthe world. Its topography is typical of ‘basin-range’ deserts, char-acterised by enclosed drainage systems (Cooke et al., 1993). Samaca isone of several basins constituting the course of the lower Ica River, cutinto the Tablazo de Ica sedimentary rock plateau (Fig. 1). It is a well-defined and convenient landscape unit within which to consider keygeomorphological agents affecting a lowland valley system and inparticular human–environment interactions (French, 2003). Theclimate is hyperarid with an average annual precipitation of only0.3 mm (ONERN, 1971). In this environment there are only two

nes), [email protected]

ll rights reserved.

natural geomorphological agents acting, in opposite directions, withinthe Samaca Basin: the wind and the river.

The Río Ica exhibits a different configuration to the broad fan-shaped delta complexes of most major Peruvian westward-flowingcoastal rivers. Blocked by the uplifted formations of the Tablazo de Ica,it is diverted south, parallel to the coast, for 150 km. Alluvial sedimentsare deposited in a series of wide basins that alternate with narrowsand canyons. Life and human settlement since at least the EarlyHorizon (Cook, 1999, Fig. 2) have been restricted to these riparianoases. The hydrology is erratic and seasonal, arising from summerrainfall in the distant Andean highlands; flow lasts for around threemonths per year. Total surface flow since 1922 has oscillated widelyabout a mean of 257 million m3 per annumwith a standard deviationof over 150, but with annual flows of over 800 million m3, related toperturbations in the Southern Oscillation Index or El Niño (Beresford-Jones, 2005), and many years with practically no flow (SENAMHI-Ica,1997, 2002).

The wind regime of the lower Ica Valley is extraordinarily strongand unimodal, from the south (Parker Gay, 1999). Mega-yardangshundreds of metres high etched upon the surface of the Tablazo de Icatestify to the stability of this wind regime over great time depths(McCauley et al., 1977; Beresford-Jones, 2005). The average monthlywind velocities measured continuously by Davis cabled weatherstation over seven months, varied between 32.3 (for October 2004)and 27.1 km/h (for December 2004). Maximum gusts recorded variedbetween 115 and 82.1 km/h (Personal communication — Ing. AlbertoBenavides).

mailto:[email protected]:[email protected]:[email protected]://dx.doi.org/10.1016/j.catena.2008.12.010http://www.sciencedirect.com/science/journal/03418162

Fig. 1. Lower Ica Valley (Landsat 7 ETM+ 2000).

235D. Beresford-Jones et al. / Catena 78 (2009) 234–249

Detailed geomorphological survey concentrated upon a c. 50 haarea of the upper Samaca Basin, known as ‘H-13’ (Cook, 1994), whichexhibits evidence of environmental degradation and diminished land

Fig. 2. Simplified Ica Valley Pr

use over time. The purpose of the survey was to describe andcharacterise sediment and soil sequences to gain insight into thedifferential processes of deposition and erosion though alluvial andaeolian action in the basin over time. Understanding these processes isrequisite to any attempt to reconstruct human impact on vegetationand land use change, interpret extant archaeological and landscapefeatures identified by archaeological survey, and identify prospectiveareas for archaeological excavation.

This article describes the methods used in carrying out thegeomorphological survey and its results and interpretations, whichinclude the definition of the basic geomorphic units across theupper Samaca Basin, the nature of the relict river terrace underlyingH-13, the extent of landscape and ecological change across H-13 asrevealed by buried soils, and evaluation of contexts from whicharchaeological and archaeobotanical data were extracted and subse-quently analysed.

2. Methods

Geomorphological study was carried out along a systematictransect of 31 survey pits located 25 m (occasionally 50 m) apart,proceeding due west between the sedimentary base rock edges of theSamaca Basin (Fig. 3). Field descriptions were made of the exposedsoil and sediment profiles following Hodgson (1974) and usingMunsell (2000).

Bulk samples were collected from selected horizons for a series ofanalyses in theUniversity of Cambridge Physical Geography Laboratory(Beresford-Jones, 2005): 1) magnetic susceptibility (‘Mag Sus’),following Bennett et al. (1990); 2) Loss-on-ignition (‘LOI’) followingBengtsson and Enell (1986) at 105, 550 and 950 °C, a widely usedmethod to estimate moisture, organic matter and carbonate contentsrespectively because it is inexpensive, rapid and involves no hazardouschemicals (Dearing, 1986; Konen et al., 2002); 3) electrical conductiv-ity (‘EC’); and 4) grain size analysis using a Malvern Mastersizer 2000laser particle sizer.

Problems and limitations with LOI analysis have been reported(Heiri et al., 2001). In addition to organic carbon for exampleincreasingly higher temperatures up to 550 °C can drive off structuralwater from clays and other inorganic constituents, decompose somecarbonates and hydrated salts and oxidise Fe2+ (Schulte and Hopkins,1996). However, sediments from the hyperarid Samaca Basin contextare generally clay-poor and calcareous, for which LOI produces results

e-Columbian Chronology.

Fig. 3. Samaca Basin geomorphological survey transect and profile.

236 D. Beresford-Jones et al. / Catena 78 (2009) 234–249


with accuracy comparable to more sophisticated geochemical meth-ods (Dean, 1974). The meanings and limitations of the LOI deriveddata are discussed in its interpretation below.

Grain size analysis sampleswere run twiceusing twodifferent lenses(45 and 1000 µm) to get a full range of grain sizes (2000–0.02 µm).10 gsampleswere treatedwith 40ml of 4.4% sodiumpyrophosphate at 90 °Cfor 3 h to aid disaggregationprior to analysis. Treated sampleswere thencentrifuged at 3500 rpm for 13 min, decanted and re-mobilised beforeintroduction to the laser particle sizer.

Targeted sampling for soil thin section analysis was also under-taken; thin sections were produced in the McBurney GeoarchaeologyLaboratory, University of Cambridge (after Murphy, 1986), andanalysed (following Bullock et al., 1985) in the Oxford UniversityResearch Laboratory for Archaeology and the History of Art using aNikon Optiphot-2 polarising microscope.

3. Results

3.1. Basic geomorphic units

The survey defined an asymmetrical distribution of four basicgeomorphic units from east to west across the upper Samaca Basin asfollows:

1. A short footslope covering 100m of the transect (Survey Pits 1/001to 1/005), with a sequence consisting of: 1) a colluvial surface ofpoorly sorted coarse to medium sands and small rocks (to 5 cm)gradually diminishing westwards, overlying; 2) shallow, very wellsorted, massive aeolian fine sand deposits with occasional charcoallenses, overlying; 3) well sorted, massive, hard silty clay loamlayers with varying degrees of calcium carbonate concretion andiron staining.

2. The current Río Ica floodplain covering 300 m of the transect(Survey Pits 1/006 to 1/012), and the only part today with riparianflora, in largely degraded associations. The floodplain consists of:newly stabilised dunes; massive, laminated silty clay crusts offluvial and alluvial deposition (known locally as yapana); incisedchannel walls at the river thalweg; and overbank depositscomposed of interbedded fine layers of medium to fine sand alongnumerous channel bedswithwell-rounded rocks. The groundwatertable in the floodplain was encountered at c. 209 m asl.

Fig. 4. Deflated duracrete surface of terrace H-13 w

The highly disturbed deposits across the floodplain are indicative ofrecent high-energy flood events, including that of the 1997/98 ElNiño, which left overbankflood deposits up to 213.3masl. Typical ofdryland compound rivers with highly erratic discharges, the Río Icais laterally unstable and experiences a rapid transition frommeandering to braided channel flow during these events (Schumm,2003). During braided flow, river channels fill the whole availablespace between low terraces (Graf, 2002). ‘Floodplain’ here thusincludes the entire area influenced by lateral instability of the riverduring these high-energy events. The complex first-order topo-graphy of the floodplain has come about through vertical accretionwith overbank flow depositing fine-grained materials in horizontalbeds, with lateral accretion in cross-bedded forms as coarsematerials are deposited in lag deposits from exceptional flows.After flooding, as the river gradually returns to meandering flow,the many minor channels of the braided system become filled withfine sediments. These processes are highly influenced by theoccurrence and nature of riparian floodplain vegetation, particu-larly of phreatophytes such as Prosopis, the keystone arborealspecies in the area (Beresford-Jones et al., in press). Unsurprisingly,archaeological remains are scarce within the floodplain area.

3. A relict river terrace standing around 5 m higher than the floodplainand 10 m higher than the current Río Ica thalweg, with a width ofabout 550m along the transect (Survey Pits no. 1/013 to 1/029). Thesurface of this terrace contains frequent archaeological featuresdefined as area H-13, discussed in detail below. In general its sedi-ments comprise: even, parallel beds of well consolidated, blocky siltyclay loams with numerous ferric features and calcite nodules;structureless, well sorted, fine sandy loams with few calciumcarbonate concretions; and massive, well sorted, very fine sandyloams. In certain horizons calcrete cementation attains very hard,petrocalcic desert duracretes. Theseduracretes have aprofoundeffecton the land surfaceofH-13 as discussed below. The high, unvegetatedrelict terrace is exposed to the full force of the very strong, unimodalwind regime of the region. The effects of aeolian deflation of theH-13landscape are evident in frequent palimpsests of multiperiod surfacescatters of ceramic sherds, and complex second-order landformscreated by a classic inversion of relief, whereby features such ascanals, which were once cut into the land surface, are preserved byduracrete enrichment as upstanding features above the deflatedsurrounding landscape (Maizels, 1988; Cooke et al., 1993; Fig. 4).

ith relict canal Feature No. 40 in foreground.

Table 1Section 1/013 field descriptions.

Depth (cm) Colour Munsell colour Description

0–42 Very pale brown 10YR 7/3 Silty clay; massive to crumb; hard, consolidated; ferric mottles (2–5 mm) common42–48 Brown 7.5 YR 4/3 Silt loam; sub-angular blocky (1–2 cm), moderately well developed, hard; numerous ferric mottles; CaCO3 nodules48–53 Light olive brown 2.5Y 5/3 Fine sandy loam; structureless; moderately well sorted; CaCO3 concretions (2–4 mm)53–65 Light yellowish brown 2.5Y 6/3 Fine sandy loam; massive; moderately well sorted65–73 Brown 7.5YR 4/3 Silt loam; crumb to blocky; hard, consolidated; ferric mottling; CaCO3 concretions (1–3 mm); roots73–75 Light olive brown 2.5Y 5/3 Very fine sandy loam; structureless75–83 Light olive brown 2.5Y 5/3 Fine sandy silt; massive; moderately well sorted83–90 Brown 7.5YR 4/4 Silt loam; crumb to blocky, poorly developed; CaCO3 concretions; same as 65–73 cm90–110 Light yellowish brown 2.5Y 6/3 Same as 53–65 cm110–125 Brown 7.5YR 4/4 Same as 83–90 cm125–130 Light olive brown 2.5Y 5/3 Fine sandy loam; structureless130–145 Brown 7.5YR 4/4 Silt loam; massive; well consolidated; CaCO3 concretions; roots145–155 Brown 7.5YR 4/4 Silt loam; sub-angular blocky, moderately well developed; CaCO3 concretions; rootlets to large roots155–165 Brown 7.5YR 4/4 Same as 130–145 cm165–182 Brown 7.5YR 4/4 Loam; blocky to crumb, weakly developed; poorly sorted; CaCO3 concretions common; small

sub-angular gravels; ferric mottling; roots.182–205 Light olive brown 2.5Y 5/3 Very fine sandy silt loam; massive205–226 Light olive brown 2.5Y 5/3 Medium sandy silt; massive226–240 Light olive brown 2.5Y 5/3 Very fine sandy silt; massive240–245 White 2.5Y 8/1 White calcrete horizon; hard245–255 Brown 7.5YR 4/4 Sandy loam; massive, moderately well consolidated255–265 Brown 7.5YR 4/4 Silt loam; massive; hard265+ Light brownish grey 10YR 6/2 Medium to coarse sand; structureless


4. The western end of the transect (Survey Pits, 1/030 and 1/031) is alarge climbing dune, anchored on the sedimentary rock slope onthe western flank of the basin. This part of the transect isparticularly important because climbing dune deposits seal buriedland surfaces, elsewhere lost across the surface of the H-13 terracebecause of wind deflation. These surfaces are discussed in moredetail below. In general the profiles here comprise: poorlyconsolidated coarse to fine sand in graded bedding, at the base ofwhich are frequent cultural materials; overlying massive, moder-ately well consolidated, moderately sorted layers of fine sandy siltloam, with evidence of fining upward sequences, i.e. fine sand atthe bottom grading upward to silt, with frequent ferric staining andfew cultural materials; overlying hard, consolidated, brown siltyclay with well developed blocky structure (1–5 cm).

These basic geomorphologic units are illustrated in Fig. 3, whichshows the profile of the entire transect, as well as the probable ancientland surface level of H-13 determined from the height of the preservedrelict canal (Feature 40) and other preserved archaeological features, asdiscussed below. Also shown are the April 2002 groundwater levelduring survey, themaximum level of the 1997/98 El Niño event, and thelevel of a huge flood event that deposited fluvial layer Stratigraphic Unit19 (‘S.U. 19’), recorded during excavation (Beresford-Jones, 2005).

Table 2Section 1/013 analyses results.

Layers Loss on ignition (by mass) Mag Sus(LF Sus)

EC(mS/cm)

Grain

Depths(cm)

% Loss at105 °C

% Loss at550 °C

% Loss at950 °C

% Silicateresidue

% Siltclay (

0–42 5.0 4.3 3.1 91.2 88 7.33 9342–48 8.4 4.8 3.4 90.2 290 11.34 8948–53 1.5 1.3 10.6 83.4 210 2.67 4453–65 2.1 1.8 3.8 92.7 345 3.41 5265–73 5.6 3.4 2.8 92.6 459 7.78 7173–75 1.0 1.5 1.8 96.0 15 2.37 4775–83 3.2 2.4 2.6 93.8 345 4.7 6583–90 5.7 4.2 4.0 90.0 382 7.45 81

Notes:(1) grain size b63 µm.

(2) grain size N63 µm.

(3) grain size 63–2 µm.


3.2. Section 1/013 — relict terrace H-13

A steep 5 m embankment incised by the river at some point in thepast marks the edge of the H-13 relict terrace. Some 3 m of this profilewas cleaned, described and subsequently analysed in detail as Section1/013 (Table 1). The top of the embankment and sectionwas surveyedat 218.79 m asl (Fig. 3). This profile represents the history of theterrace prior to the deposition of archaeological materials dating fromthe Early through to the Middle Horizon scattered upon the surface ofthe H-13 relict terrace.

The 1/013 section is characterised by distinctive surface and subsur-face horizons in various partly repeated sequences, and fits descriptionsof aridisols according to USDA nomenclature (Cooke et al., 1993).

But episodicity in alluvial and aeolian sedimentation may producebedding that closely resemble pedogenic horizons, and as Cooke et al.(1993: 51) note “processes of sedimentation and pedogenesis arefrequently superimposed”. Key features include: sub-surface enrich-ment from inputs of fine aeolian dust; differential solubility leading todifferential distribution of salts; clay illuviation; and processesassociated with fluctuations in ground water levels (Cooke et al.1993: 51). All of these processes are interrelated and may beassociated with both natural and cultural activities. Flooding forexample can be related to human manipulation of watercourses;

size analysis summary

and1)

% Sand(2)

% Silt(3)

% Clay(4)

Sortingcoefficient

Mediandiameter(µm)

Meandiameter(µm)

Inclusivegraphicskewness

8 80 12 1.97 12.16 43.2 0.14111 60 28 2.50 5.70 37.8 −0.12956 35 9 2.57 82.86 107.4 0.55048 43 9 2.40 57.63 70.7 0.51329 49 23 2.85 9.50 64.6 −0.10453 38 8 2.61 75.36 124.8 0.49835 54 11 2.41 37.83 54.4 0.41119 57 24 2.61 7.88 31.3 −0.085

Fig. 5. Grain size profiles for Section 1/013 profile.

Fig. 6. Variations with depth of sele


changes in vegetation cover can alter aeolian deposition, as well asleading to carbonate mobilisation in the soil (Goudie, 1973). Togetherthey give rise to complex profile sequences whose underlying causalprocesses are difficult to disentangle.

Secondary calcium carbonate enrichment is a common feature ofarid zone soils (Cooke et al., 1993), and is the defining characteristic ofthe H-13 relict terrace. Very tough enriched CaCO3 duracrete horizonsare known as calcretes or calíche on the south coast of Peru. Mostcalcrete horizons in arid area soils are pedogenic; their formation anddevelopment is influenced by several factors including texture of thehost material, partial pressure of CO2 in the soil air, rate of supply ofcalcium, amount of infiltrating water, profile age, and the climatichistory of the site (Cooke et al. 1993: 56–60, Goudie, 1973, 1983).

Estimates of the age of duracretes vary widely. Most are thought tobe very ancient: from 10,000 BP to as far back as the Miocene (Cookeet al., 1993). However duracretes formed from floodwaters maydevelop quite quickly (Machette, 1985), and the preponderance ofcalcrete deposited to over 3mdepth observed in the base of relict canalfeature No. 40 during excavation (Beresford-Jones et al., in press),suggests that at least some of the duracrete of terrace H-13 may relateto anthropogenic floodwater manipulation during the archaeologicaltime periods. The Samaca climate is hyperarid and has likely persistedfor millions of years (Petrov, 1976; Alpers and Brimhall, 1988; Cookeet al., 1993; Böhlke et al., 1997; McKay et al., 2003). Whilst climatechange in the immediate vicinity does not likely explain duracreteformation during the time period discussed here, any long-termvariations in seasonal rainfall on the distant Andean foothills(Eitel et al., 2005; Mächtle et al., 2006) would have affected ground-water levels. In Samaca, as in many deserts of the USA (Machette,1985; Schlesinger, 1985), the primary source of calcium carbonateenrichment is likely to be dust input fromwinds blowing for millenniafrom the Pacific Ocean, over the highly calcareous sedimentaryformations of the Tablazo de Ica.

Data from laboratory analyses (Table 2), field descriptions (Table1), and grain size profiles (Fig. 5), show a series of discernible episodic

cted Section 1/013 profile data.


sequences down the 1/013 profile (B–B′ on Fig. 6), below its upper-most stratigraphic unit (0–42 cm). Although data for only the upperpart of the profile have been determined, the observed sequencesappear in field description to repeat to depth throughout of the entireSection 1/013 (Table 1). They consist of:

1. Thin, brown (7.5YR 4/3) silty clay loams (42–48 cm; 65–73 cm and83–90 cm): with sub-angular blocky structures, numerous ferricmottling and calcite nodules; with relatively high LOI readings at550 and 105 °C and relatively high electrical conductivity andmagnetic susceptibility levels. They have bimodal grain size profileswith negative inclusive graphic skewness towards silts and clays.

Fig. 7. Samaca Basin, curren

2. Underlying, relatively thin, light olive brown (2.5Y 5/3), structure-less sandy loams (48–53 cm and 73–75 cm); with very low LOIreadings at 550 and 105 °C and low electrical conductivity andmagnetic susceptibility levels. They have grain size profiles withpositive inclusive graphic skewness towardsmoderatelywell sortedfine sands.

3. Underlying, relatively thick light yellowish brown (2.5Y 6/3) orlight olive brown (2.5Y 5/3), massive sandy loams (53–65 cm and75–83 cm); with intermediate LOI readings at 550 and 105 °C andelectrical conductivity and magnetic susceptibility levels. Theyhave grain size profiles that are still well sorted but have lesspositive inclusive graphic skewness towards coarser materials.

t floodplain sequence.


We interpret these sequences as representing the history of theH-13 terrace when it was part of the active river floodplain in thedistant past. Episodic seasonal flood deposition of alluvial silts andclays (1 above and B′ in Fig. 6) was followed by subsequent dry periodswith aeolian deposition of well-sorted fine sands in varying energies(2 and 3 above andB in Fig. 6) as seasonal riparian vegetation graduallybecame established upon damp alluvium (Fig. 7).

LOI at 105 °C represents a measure of pore water held within thesample and is used here as a crude proxy for moisture content. Sharpdiscontinuities in moisture readings down the profile emphasise thecurrent standstill condition of the H-13 terrace system in this hyper-arid environment. The existence of thin, dry layers (e.g. 73–75 cm)that are more than 50% sand with large amounts of pore space butwith only about 1% moisture would seem to eliminate the likelihoodof ongoing hydrological continuity or capillary action from the basinwater table up the profile.

LOI at 550 °C, following Dean (1974), is here taken as a relativelyaccurate measure of organic carbon matter content in the particularcontext of the lower Ica Valley. The measure does not distinguishbetween elemental carbon and other organic matter, althoughcharcoals were not noted in 1/013 contexts, either in field descriptionsor archaeological flotation using 500 µm mesh. These proxy organicmattermeasures are very low for these contexts, as would be expectedin sediments of largely clastic originwith only incipient soil formationin an arid environment. Organic matter content is significantly higherin putative alluvial deposits (B′ in Fig. 6) at around 4.5%. Indeed, thesevalues are fairly typical for alluvial silts, whose fertility when annuallyreplenished, has of course little to do with their organic contents.

Fig. 8. Prosopis calcium carbonate pseud

When LOI at 550 °C across all the 1/013 data is plotted as a functionof grain size for each grain size class, whilst a strong positivecorrelation is noted for finer grained sediments (e.g. R2=0.775 forvery fine silt), with increasing grain size this correlation steadilybecomes weak (e.g. R2=0.024 for very coarse silt), and then morestrongly negative (e.g. R2=−0.899 for fine sands). This observationtogether with those above may indicate that organic matter in thesecontexts is mainly represented by finely divided organic matterbrought in with alluvium.

Magnetic susceptibility readings show wide fluctuation down the1/013 profile from a high of 383 in silt layers of proposed flooddeposition to a low of only 15 (S.I. units x 10−8 m3 kg−1) in putativeaeolian deposit layers (Fig. 6). However it is not correlatedsignificantly with % silt and clay (R2=0.031). This may be becausevery highmagnetic susceptibilities observed in putative flood deposits(e.g. 42–48 cm) are the result of their post-flood exposure, prior togradual burial by aeolian deposits and establishment of vegetation.

LOI at 950 °C in this context is taken as a fairly accurate measure ofcalcium carbonate content since there are no magnesium carbonatecontaining rocks in the Río Ica catchment (ONERN, 1971). Althoughcalcite contents generally vary in accordance with the observedepisodic sequence there are notable exceptions (e.g. the high contentof layer 48–53 cm and the white petrocalcic K horizon of almost purecalcrete at 240–245 cm). Calcite enrichment is thus largely theproduct of processes of secondary enrichment (Goudie, 1973;Raghavan et al., 1991) and suggests much higher groundwater levelsfrom those persisting today some 10 m beneath the standstillcondition terrace.

omorphs in H-13 duracrete layers.


Although EC is strongly positively correlated with percentage siltsand clays (R2=0.804), calcite contents are not (R2=−0.153).Calcrete formation here therefore does not appear to conformstraightforwardly to the model proposed by Gile (1966), Gile et al.(1997), in which laminations form as water through-flow ischannelled over a plugged, fine textured hardpan. However anotherfactor in H-13 calcite enrichment may be previously extant riparian

Fig. 9. Context and details

vegetation. Dominant calcite rhizoliths and Prosopis leaf litterpseudomorphs are observed in calcrete horizons across the barrensurface of H-13 (Fig. 8), and nodules within in and below the proposedalluvial layers of Section 1/013 (Table 1). These may indicate drawingof groundwater up-profile by roots (Goldberg and Macphail, 2006) orchanges in CO2 partial pressures in the rhizosphere (Bhojvaid andTimmer, 1998; Garg, 1999; Mishra and Sharma, 2003).

of Survey Pit 1/030.


Moreover, the uppermost part of 1/013 stratigraphy shows anumber of striking contrasts to the underlying sequence thus fardiscussed. This thick (0–42 cm), upper unit of pale brown, massivesilty clay with frequent ferric mottles (Table 1) exhibits significantlyless sorting and a symmetrical grain size profile about a median,medium silt, quite distinct from underlying layers (Table 2 and Fig. 5).In view of the relict canal system across the surface of H-13 it istempting to interpret this distinction as the result of the imposition ofhuman control, agriculture and pedogenesis upon the energies of theepisodic clastic sediment regime of the underlying river floodplain.

Although of considerable thickness, this is interpreted as a truncatedlayer since it is apparent from the extant form and distribution ofarchaeological evidence, exemplified by relict canal fragment Feature 40(Fig. 4), that the relict H-13 terrace surface has undergone severedeflation over time. The characteristics of canal Feature 40 establishedthrough excavation and survey (Beresford-Jones, 2005), including itsdirection parallel to the river, substantial dimensions, long duration ofuse, and unlined channel form, all fit Moseley et al.'s (1983: 316) Class 1canal: a principal supply canal, supporting a sub-critical flow regime,with a gentle down-course gradient. Based upon survey of this canalfragment (average extant surface of 220.06 m asl; maximum surfacealtitude of 220.88masl) the original land surface of theH-13 terrace canbe estimated to have lain at around 220.5 m asl. Survey of the deflatedflanks of the canal (average 218.55m asl, and coincident with the top ofSection 1/013), implies some 2 m of deflation since its abandonment.Thus the 0–42 cm layer observed today in Section 1/013 is likelytruncated by some 1.5–2 m of wind deflation, and represents only thebottom part of the original surface profile of the terrace when canal 40was in operation.

The amount of entrainment of grains by wind and thus of aeoliandeflation experienced in a particular environment is a complexfunction of wind speed; surface conditions including vegetationcover; and grain size and cohesion, which in turn depend uponproperties such as moisture and salt enrichment (Fryberger and Dean,1979; Maizels, 1988; Cooke et al., 1993). But since the date by whichthe H-13 relict terrace was completely abandoned by vegetation canbe estimated through various lines of archaeological data, discussedbelow, to around the end of the Middle Horizon we can estimate theaverage rate at which the stable, unimodal Samaca wind regime isdeflating the terrace. This is useful because, as Cooke et al. observe,‘there are few reliable measurements of rates of transport in the field’(1993: 263). Assuming a deflation depth as determined above, thetotal volume of material removed from the surface of the H-13terrace, much of it deposited in the climbing dune anchored on thewestern edge of the basin, can be estimated by GIS to total some377,000 m3. The flank of the terrace perpendicular to the unimodalSamaca wind direction is around 1100 m in length, which implies anaverage deflation rate of around 0.31 m3 (m width)−1 yr−1; or, byaround 2 mm depth per year.

3.3. Survey Pit 1/030 — buried land surface and buried soil

In this deflated landscape only the western end of the transectsealed beneath the climbing dune seemed to offer possibilities of

Table 3Survey Pit 1/030 field descriptions.

Depths (cm) Colour Munsell colour Description

0–33 Light brownish grey 10YR 6/2 Fine to coarse sand with graded be33–46 Dark greyish brown 10YR 4/2 Sandy loam; massive; moderately w

marine mollusc shell frequent. At b46–60 Brown 10YR 4/3 Silt loam; massive; well consolidate60–124 Brown 10YR 4/3 Sandy silt loam; well developed blo

moved down fissures; charcoal (1 m124+ Greyish brown 10YR 5/2 Silt loam; sub-angular blocky to cru

calcite nodules (1–5 mm), (same a

buried land surfaces. Survey Pit 1/030 was located at the very base ofthe climbing dune at a surveyed altitude of 219.89 m asl (Fig. 3). Thealtitude of the base of this pit was therefore approximately coincidentwith the top of Section 1/013, some 560 m distant across the relictterrace H-13 (Fig. 3). Survey Pit 1/030 was later expanded to becomethe first quadrant (1A) of 3×1 m Test Pit No. 1 (Fig. 9; Table 3).

The profile for Survey Pit 1/030 was unique among all thoserecorded on the survey transect because it appeared to includeevidence of a buried soil horizon. In summary this profile comprised:1) a surface layer (0–33 cm) of unconsolidated, graded sandsconstituting the aeolian deposit of the climbing dune, overlying2) a sequence of moderately well consolidated and moderatelysorted sandy and silt loams (33–46 cm and 46–60 cm), over 3) abrown, well developed blocky, sandy silt loam (60–124 cm). Thislatter element was tentatively identified in the field as a buried soilhorizon.

Three samples for soil micromorphological analysis weretherefore taken from the interfaces across 46–60 cm and 60–124 cm to further refine the characterisation and interpretation ofthis profile: Samaca 5 (46–54 cm); Samaca 2 (55–67 cm) andSamaca 4 (68–80 cm), (Fig. 9C).

Thin sections Samaca 5 and Samaca 2 have well-accommodatedsubangular blocky microstructure with short planar voids and illuvial‘dusty’ clay inclusions within the thin cracks and voids (Fig. 10). Thefine groundmass of the deposits is weakly to moderately striated, atypical characteristic of clay-rich sediments undergoing shrink–swellprocesses associated with periodic wetting and drying. Iron mottlesand manganese nodules are also associated with these cracks andchannels, and the groundmass is stained with oxidised iron. Samaca 2also shows polyconcave voids, suggesting soil collapse related towatersaturation. These layers appear to be alluvial, representing low-energyflooding, possibly with some aeolian input. Later illuviation andshrink–swell/wet–dry processes have created many of the maincharacteristics of the horizon. Sands do not seem to contribute muchuntil after primary deposition.

Thin section Samaca 4 appears to confirm its identification as anold soil horizon. Some aggregates similar to the fabrics describedabove appear near the top of the thin section. However themain fabricis light brown under plane polarised light, and is more stained withamorphous organic matter than the iron-stained fabrics of theoverlying sections (Fig. 10). Coalesced crumb peds and microaggre-gates suggest reworking by soil fauna for some time.

Although organic materials within the thin section appeardepleted, they are nevertheless still a major component of the sectionat between 15 and 20% (visual estimate of area). Some ‘dusty’ claycoatings occur, but there are relatively few clay infillings and thegroundmass is mainly stipple specked. The sandy loam texture ismuch more mixed than that of the layers above. The generally moreorganic and mixed nature of this horizon suggests that it was a soilhorizon proper at some time, which was subsequently buried by lowenergy alluvial deposits. This sequence was then overlain by theaeolian deposits of the climbing dune. Because of deflation of H-13and the removal of its once extant stratigraphy, only isolated frag-ments of this soil layer are observed outside the area sealed by the

dding, alternating layers of well sorted grain sizes; poorly consolidated in lower 15 cmell consolidated, moderately sorted; charcoal (1 mm–3 cm) common;oundary with level below — very fragile wood, (same as 1/028 4–32 cm)d; moderately sortedcky (1–5 cm); well consolidated, hard; material from above hasm–2 cm) commonmb (1–2 cm), moderately well developed; hard, well consolidated,s 1/026 25–45 cm)

Fig. 10. Micrographs of Survey Pit 1/030 thin sections.



dune, most notably along parts of the eastern flank of relict canalFeature No. 40, which are protected from the effects of unimodal winderosion by the canal itself.

It is worth reemphasising the significance of the identification ofalluvial deposits, overlying a once organic buried soil horizon, in themidst of a today's barren landscape, over half a kilometre west, andabout 5 m above, the edge of the current riparian Río Ica floodplain(Figs. 3 and 9). As Survey Pit 1/030 was expanded to form Test Pit 1,and its unconsolidated aeolian climbing dune deposits were brushedaway, a remarkably preserved print of an individual's left foot wasfound on the surface of the hard, underlying silt–loam (33–46 cm,S.U. 5 in Test Pit 1), (Fig. 9). This footprint is further, rather poignant,evidence that S.U. 5 represents an ancient surface, buried and protectedby the climbing dune. Indeed, when the individual stepped upon thissurface, it was moist.

3.4. Survey Pit 1/031 — gradual aeolian deposition

Survey Pit 1/031marked thewestern limit of the transect, 25 m upthe ascending face of the climbing dune from 1/030 at a surveyedaltitude of 222.43 m asl, some 2.5 m higher than the dune surface at1/030. The base of Survey Pit 1/031 therefore lay around 0.5 m higherthan the surface at 1/030 (Fig. 3).

The upper 0–64 cm of Survey Pit 1/031 comprised light brownishgrey, unconsolidated fine to coarse sands in graded bedding (Table 4;Fig. 11), constituting the aeolian deposits of the climbing dune.The rest of its profile exhibited frequent evidence of archaeologicaldeposition including midden materials, significant amounts ofcharcoal and an in situ hearth. In addition its sequence includedsignificant quantities of desiccated Prosopis tree litter (known locallyas poña).

Data derived in subsequent laboratory analyses (Table 5 andFig. 11) show a steady increase in the proportion of fine materialsdown the profile, and no clearly discernible repeating sequences, likethose noted in the data of Section 1/013.

Interspersed among the upper parts of the sequence is frequentevidence of anthropogenic activity. The identification of Nasca 2/3ceramic fragments in the 76–80 cm unit, near the top of the sequence,dates these deposits to the Early Intermediate Period. Layer 92–98 cmshows high readings for carbonates, electrical conductivity andmagnetic susceptibility, reflecting its interpretation as an in situhearth. Magnetic susceptibility readings are particularly high indeposits with anthropogenic input.

Organic matter readings increase down the profile and show veryhigh levels for arid area sediments (e.g. 10.4% for layer 98–102 cm).These reflect the significant quantities of desiccated plant macro-fossils dominated by Prosopis tree litter that increase down the

Table 4Survey Pit 1/031 field descriptions.

Depths (cm) Colour Munsellcolour

Description

0–30 Light brownish grey 10YR 6/2 Coarse to fine sand in graded beddin30–64 Light brownish grey 10YR 6/2 Medium sand, unconsolidated, weak64–76 Dark yellowish brown 10YR 4/4 Sandy loam; poorly consolidated, st76–80 Dark yellowish brown 10YR 4/4 Frequent organic inclusions in samem80–92 Brown 10YR 4/3 Sandy silt loam; sub-angular to sub-

organic inclusions: Prosopis sp. leave92–98 Very dark grey 7.5YR 3/1 Charcoal (to 8 mm) and ash (in-situ98–102 Black 7.5YR 2.5/1 Charcoal, ash, charred poña leaf litte102–120 Strong brown 7.5YR 4/6 50% organic matter/50% silty sand m

of massive, moderately well consoli120–140 Yellowish brown 10YR 5/4 Same as above but with 33% poña le140–190 Pale brown 10YR 6/3 Sandy silt loam with c. 10% organic

hard, sandy silt loam (similar to 1/0190+ Yellowish brown 10YR 5/4 Silty sand; well consolidated, massiv

in layers above. Capped by hard clay

profile. The excellent preservation of both plant macro fossils andpollen extracted from Survey Pit 1/031 contexts (Beresford-Jones,2005; Beresford-Jones et al., in press) demonstrate that they wereabove the sequences of high pH floodwater wetting and drying thatcharacterise the layers of 1/030, some 2.5 m lower down on thesurface of H-13.

In a unidirectional wind regime, the western flank of the basin andthe deposits of Survey Pit 1/031 are interpreted as the surfaces uponwhich progressive accumulation of aeolian materials have becomeanchored and deposited over time. The energy of this depositionappears to have increased over time, with finally the graded sandaeolian deposits of the climbing dune. The preponderance of fossiltree litter observed at depths of up to 140 cm is evidence of treesgrowing close to this location.

4. Discussion and conclusions

We beganwith the observation that first stimulated this research –the extensive basins of the lower Ica Valley have abundant archae-ological remains and yet today support few people and littleproductive agriculture – thereby presenting a prima facie case fordramatic landscape change. The geomorphological survey that wehave described is the basis of research that seeks to combinearchaeological survey and archaeobotanical analysis to answer thequestions of when andwhy this change occurred. The story it tells is asfollows.

Today, the floodplain of the Río Ica in the Samaca Basin is narrow. Ithas a highly disturbed geomorphology –with overbank deposits, siltyclay alluvial crusts and newly stabilised dunes of remobilised riverbeddeposits – indicative of laterally unstable, high-energy flood events. Atsome time in the past the river has incised into its floodplain, exposingthe 5 m embankment described as Section 1/013 and creating theH-13 relict terrace.

The deep-time history of H-13, recorded in this section showsrepeated episodes of flooding – with the deposition of alluvial silts –followed by dry periods –with increased aeolian inputs of well-sortedfine sands. During this time the terrace was part of the active riverfloodplain. However, the upper part of the Section 1/013 sequencereflects a very different environment: one under a controlled energyregime, perhaps indicative of human influence and control over theprocess of episodic sedimentation and of pedogenesis. This is quiteunsurprising in view of the ancient canal systems preserved across thesurface of the H-13 terrace.

Pollen data from the 1/031 contexts and plant macrofossil datafrom various excavated contexts across H-13 provide evidence that inthe Early Intermediate Period the terrace sustained productivefloodplain agriculture of maize, cotton and other domesticated plants

g; poorly consolidatedgrading

ructureless; organic matter: poña, wood, root, Prosopis sp. leaves, charcoal (1–4 cm)atrix as above: twigs, beans, seeds, insect remains, wood, Nasca 2/3 phase ceramic fragmentsrounded gravels (1 cm); poorly consolidated, poorly sorted, structureless;s, poña leaf litter, charcoal (few), wood fragments, ceramic fragmentshearth)r.atrix. Organic matter exclusively poña leaf litter. Aggregates (2–20 cm)

dated silty sand; random orientationaf litter/66% matrixmatter. Aggregates as above but also aggregates (1–8 cm) of well consolidated,30 46–124 cm)e, moderately sorted; ferric mottling. Material for some aggregateslayer (8–10 cm).

Fig. 11. Survey Pit 1/031 grain size profiles.


within a landscape still dominated by Prosopis woodland (Beresford-Jones, 2005; Beresford-Jones et al., in press). Over 60 relict Prosopistree stumps preserved in this hyperarid climate have been surveyedand excavated across today's barren H-13 landscape (Fig. 3).

When did the river incise into its floodplain to expose the H-13terrace? Various evidence link this river entrenchment event to afluvial layer labelled S.U. 19 recorded during the excavation of Test Pit4 on a secondary terrace just below H-13 (Fig. 3). Preserved fragmentsof S.U. 19, up to 60 cm deep, were surveyed at scattered points in thelandscape (Fig. 12). GIS simulation of the flood event that depositedS.U.19 indicates that it was huge: far greater in its spatial extent thanthe so-called ‘Super El Niño’ of 1997/8 (Bendix et al., 2002). Thisancient flood event can be dated approximately to the end of theEarly Intermediate: firstly S.U. 19 caps directly midden contexts inTest Pit 4 that date to Nasca 2/3 (Beresford-Jones et al., in press); and

secondly, our simulation shows marked coincidence with the extantforms of relict canal feature no. 40/34 and other Early Intermediatearchaeological features (Fig. 12).

Once river entrenchment had occurred, productive agriculturewasabandoned and the H-13 terrace eventually became exposed toaeolian deflation. The presence of different degrees of secondary cal-cium carbonates in the H-13 terrace, in part due to human floodplainmanagement, and the subsequent exposure of these deposits bydeflation, has created a complex second-order landformwith invertedrelief. Cemented features such as canals survive today standing abovethe deflated relict terrace, whilst artefacts spanning some 2000 yearsfrom the Early through to the Middle Horizon, have been left as mixedassemblages scattered across it. Calcite cementation also attests tohow groundwater levels in the basin have fallen: the result of the riverentrenchment described, but perhaps also indicative of long-term

Table 5Survey Pit No. 1/031 analyses results.

Layers Loss on ignition (by mass) Mag Sus(LF Sus)

EC(mS/cm)

Grain size analysis summary

Depths(cm)

% Loss at105 °C

% Loss at550 °C

% Loss at950 °C

% SilicateResidue

% Silt andclay (1)

% Sand(2)

% Silt(3)

% Clay(4)

Sortingcoefficient

Mediandiameter(µm)

Meandiameter(µm)

Inclusivegraphicskewness

64–76 1.7 1.8 2.0 95.4 355 5.73 43 58 31 11 3.27 98 195 0.41376–80 3.9 – – – 119 7.24 39 61 31 9 3.73 806 694 0.80780–92 2.8 3.9 1.8 93.5 317 5.62 44 56 35 9 2.83 89 132 0.49092–98 4.0 8.7 8.6 78.9 312 7.43 52 48 43 9 2.69 59 104 0.37898–102 4.7 10.4 3.8 84.1 259 6.37 58 42 47 11 2.87 40 102 0.242102–120 5.6 4.8 2.7 91.3 238 7.54 63 38 47 15 3.17 18 101 −0.022120–140 6.0 4.6 1.8 92.7 119 9.45 72 29 54 18 2.85 10 59 −0.156140–190 5.3 3.1 3.2 92.2 254 7.53 78 22 62 16 2.64 10 60 −0.163190+ 2.3 1.5 0.9 97.2 106 3.62 – – – – – – – –

Notes:(1) grain size b63 µm.


(3) grain size 63–2 µm.



rainfall changes in the distant upper Río Ica catchment (Eitel et al.,2005; Mächtle et al., 2006).

These archaeological data thus approximately date the processes ofgeomorphological change. Archaeological survey of the H-13 relictterrace revealed almost no materials that post-date the MiddleHorizon, despite the presence of two large Late Intermediate to LateHorizon habitation sites in the lower Samaca Basin (Cook, 1994;Beresford-Jones, 2005). We adduce therefore that sometime towardsthe end of the Middle Horizon this terrace had become an entirelydegraded landscape without any vegetation cover and completelyexposed to the effects of the region's extraordinary wind regime. Thedifference in heights between the indurated extant canal surface andthe surrounding deflated landscape can therefore be used to estimatethe ongoing rate of deflation of the H-13 terrace.

Our research thus records further evidence of the catastrophic eventsthat so characterise Andean archaeological interpretations:El Niñofloodsand/or La Niña droughts (viz., perturbations in the Southern OscillationIndex, ‘ENSO’). Ice-core records from the Quelccaya ice cap (Thompsonet al.,1985)havebeenused topostulate thatmajor climatic perturbationscorrelate with so-called ‘punctuations’ evident in the archaeologicalrecord of the Peruvian coast (see for example Shimada et al., 1991;Moseley, 1992; Silverman and Proulx, 2002). However, we also haveevidence that this punctuated equilibrium model may be simplistic.

Firstly, excavation of Middle Horizon midden contexts on relictProsopis nabkhas, or phytogenic mounds (e.g. Mound 23, Fig. 3),indicates that although the H-13 terrace was by then exposed toserious wind erosion, some large trees and human occupation stillpersisted there (Beresford-Jones et al., in press). This indicates moregradual landscape change.

Moreover, the products of that deflation have been deposited by aunidirectional wind regime as a climbing dune, anchored against thewestern flank of the basin. This deposition has buried a portion of theancient landscape along that western edge and thereby preserved it,as evidenced by Survey Pits 1/030 and 1/031. Survey Pit 1/030provides evidence about the extent of alluvial deposition and organicrich soil horizons once present on H-13, and thus of the dramatic scaleof landscape and ecological change. But the contextual evidence fromSurvey Pit 1/031, in conjunction with well preserved plant macro-fossil and pollen data, also provides evidence that geomorphologicalchange here followed the gradual removal of the keystone arborealgenus of the area, Prosopis, as well as other riparian tree species(Beresford-Jones et al., in press).

The proximate cause of the abandonment of the H-13 relict terracewas indeed river entrenchment resulting from the S.U. 19 El Niño eventat the end of the Early Intermediate Period. Similarly devastating river

entrenchments have been noted in the archaeology of the Peruviannorth coast and explained through tectonic uplift (Moseley et al., 1983).Yet, there is little geomorphological evidence of significant tectonicuplift on the Peruvian coast during archaeological time periods (Cookeet al., 1993;Wells and Noller,1999). Rather, the phenomenon of ‘arroyo-cutting’ has been known since the work of the geomorphologist KirkBryan in the 1920s in the Gila River Basin of the south-western USA, andhas been intimately linked there to the removal of riparian vegetation(Cooke and Reeves,1976; Hackenberg,1983; Nabhan,1986; Cooke et al.,1993; Graf, 2002).

Indeed, in arid riparian environments phreatophyte vegetation –exemplified here by Prosopis, which has one of the deepest and mostlaterally extensive root systems of any tree (Stone and Kalisz, 1991;Díaz Celis, 1995) – can ‘significantly alter channel geometry byincreasing bank resistance to erosion, inducing deposition andincreasing roughness’, as Cooke et al. (1993: 153) observe. The deepProsopis root architecture ‘underpins’ floodplain and river meanders,providing the edaphic conditions for other riparian species, whichtogether make for a robust, erosion-resistant system (Galan de Mera,1996, 1999). In the lower Ica Valley context, humans, graduallyclearing riparian woodland for agriculture, are the only plausibleagents of deforestation. And, this process culminated in the MiddleHorizon, a period of great social change across the Andes (Beresford-Jones et al., in press).

So, whilst our investigations confirm that major El Niño eventsaround the end of the Early Intermediate Period likely offer part of theexplanation for marked landscape change in the Samaca Basin, wealso demonstrate the significance of more gradual, human-induceddestruction of Prosopis-dominated riparian dry-forest. Prosopis pallida(known as huarango on the south coast) is a remarkable leguminoushardwood that lives for over a millennium and provides forage, fuel,and food. Moreover, it plays a crucial role in integrating fragile desertecosystems, enhancing soil fertility and moisture, and accomplishingdesalination and microclimatic amelioration (Beresford-Jones, 2005).Most obviously in an environment that frequently experiences windsof well over 100 km/h and extremely erratic river flows, trees withextensive root systems physically maintain soil stability (Pasieczniket al., 2001). Successful agriculture is simply not possible herewithoutthe protection afforded by trees.

Thus, our point here is not to deny the significance of chaoticfluctuations in the biophysical environment such as El Niño floods, butto observe that their effects would only be precipitated by ongoingprocesses of gradual, human induced change, eventually causing themto breach critical desert geomorphic thresholds. The limitation of thepunctuated equilibriummodel of Andean archaeological interpretation

Fig. 12. S.U. 19 ancient flood event.


is precisely that it relegates pre-Hispanic human culture to ecologicalpassivity, living within an effectively static landscape, periodicallyimpacted by catastrophic climatic events (and see Butzer, 1996; Wellsand Noller, 1999).

Although our archaeological focus here is avowedly environmental –both geomorphological and archaeobotanical – this does not neces-sarily make our interpretations environmentally deterministic. On thecontrary, it allows for more informed discrimination between humanagency and environmental response. Many of the changes recorded inthe extant landscape of the Samaca Basin are the products of anthro-pogenic geomorphology.

Acknowledgements

We would like to thank Julie Boreham (McBurney Geoarchae-ological Laboratory, University of Cambridge) for her meticulous

preparation of thin sections; Susana Arce (Museo Regional de Ica),Brian Pitman, Sandy Pullen, and Oliver Whaley (RBG Kew) for theirfieldwork contributions; Fraser Sturt (Dept. of Archaeology, Uni-versity of Southampton), Kevin Lane (Dept. of Archaeology, Uni-versity of Manchester) and Ing. Cesar Patroni for their survey andmapping contributions; Chris Rolfe (Dept. of Geography, University ofCambridge) for his help with laboratory work; Charly French,Elizabeth DeMarrais and Martin Jones (Dept. of Archaeology,University of Cambridge) for their advice; Mark Pollard and ChrisDoherty at Oxford University Research Laboratory for Archaeologyand the History of Art; and most importantly the people of theEscuela Libre de Puerto Huamaní and Don Alberto Benavides G. forbeing the father of it all. Funding was provided by the NaturalEnvironmental Research Council (NERC), UK, the British Academyand the McDonald Institute of Archaeological Research, Universityof Cambridge.


References

Alpers, C.N., Brimhall, G.H., 1988. Middle Miocene climatic change in the AtacamaDesert, northern Chile: evidence from supergene mineralisation at La Escondida.Geological Society of America Bulletin 100, 1640–1656.

Beresford-Jones, D.G., 2005. Pre-Hispanic Prosopis—human relationships on the SouthCoast of Peru: riparian forests in the context of environmental and culturaltrajectories of the Lower Ica Valley (http://www.arch.cam.ac.uk/dgb27/). Ph.D.Thesis, University of Cambridge, UK.

Beresford-Jones, D.G., Arce Torres, S., Whaley, O.Q., Chepstow-Lusty, A.J., in press. Therole of Prosopis in ecological and landscape change in the Samaca Basin, Lower IcaValley, South Coast Peru from the Early Horizon to the Late Intermediate Period.Latin American Antiquity.

Bendix, A., Bendix, J., Gämmerier, S., Reudenbach, C., Weise, S., 2002. The El Niño 1997/98 as seen from space — rainfall retrieval and investigation of rainfall dynamicswith GOES-8 and TRMM data. Proceedings of the 2002 Eumetsat MeteorologicalSatellite Conference, Dublin, Ireland, 3rd – 4th September, pp. 647–652.

Bengtsson, L., Enell, M., 1986. Chemical analysis. In: Berglund, B. (Ed.), Handbook ofHolocene Palaeoecology and Palaeohydrology. JohnWiley, Chichester, pp. 423–451.

Bennett, K.D., Simonson, W.D., Pelgar, S.M., 1990. Fire and man in postglacial woodlandsof eastern England. Journal of Archaeological Science 17, 635–642.

Bhojvaid, P.P., Timmer, V.R., 1998. Soil dynamics in an age sequence of Prosopis julifloraplanted for sodic soil restoration in India. Forest Ecology and Management 106,181–193.

Böhlke, J.K., Ericksen, G.E., Revesz, K., 1997. Stable isotope evidence for an atmosphericorigin of desert nitrate deposits in northern Chile and southern California, USA.Chemical Geologist 136, 135–152.

Bullock, P., Fedoroff, N., Jongerius, A., Stoops, G., Tursina, T., Babel, U.,1985. Handbook forSoil Thin Section Description. Waine Research Publications, Wolverhampton.

Butzer, K.W., 1996. Ecology in the long view: settlement histories, agrosystemicstrategies and ecological performance. Journal of Field Archaeology 23, 141–150.

Cook, A.G., 1994. Invesitigaciones de Reconocimiento Arqueologico en la Parte Baja delValle de Ica. Informe Final (1988–1990) al Instituto Nacional de Cultura del Perú, Lima.

Cook, A.G., 1999. Asentamientos Paracas en el Valle Bajo de Ica, Perú. GacetaArqueologica Andina 25. INDEA, Lima, Peru, pp. 61–91.

Cooke, R.U., Reeves, R.W., 1976. Arroyos and Environmental Change in the AmericanSouthwest. Oxford University Press, Oxford.

Cooke, R.U., Warren, A., Goudie, A.S., 1993. Desert Geomorphology. University CollegeLondon Press, London.

Dean, W.E., 1974. Determination of carbonate and organic matter in calcareoussediments and sedimentary rocks by loss on ignition: comparison with othermethods. Journal of Sedimentary Petrology 44, 242–248.

Dearing, J., 1986. Core correlation and total sediment influx. In: Berglund, B. (Ed.),Handbook of Holocene Palaeoecology and Palaeohydrology. JohnWiley, Chichester,pp. 423–451.

Díaz Celis, A., 1995. Los Algarrobos. CONCYTEC, Lima.Eitel, B., Hecht, S., Mächtle, B., Schukraft, G., Kadereit, A., Wagner, G.A., Kromer, B., Unkel,

I., Reindel, M., 2005. Geoarchaeological evidence from desert loess in the Nazca-Palpa Region, Southern Peru: palaeoenvironmental changes and their impact onPre-Columbian cultures. Archaeometry 47 (1), 137–158.

French, C., 2003. Geoarchaeology in Action. Routledge, London.Fryberger, S.G., Dean, G., 1979. Dune forms and wind regime. In: McKee, E.D. (Ed.),

A Study of Global Sand Seas. USGS Professional Paper 1052. USGS, Washington,pp. 305–397.

Galan de Mera, A., 1996. Relación entre los suelos y la vegetación del Perú. Arnaldoa 4,87–94.

Galan de Mera, A., 1999. La Clases Fitosociologicas De la Vegetación del Perú. Boletín deLima 117, 84–94.

Garg, V.K., 1999. Leguminous trees for the rehabilitation of sodic wasteland in northernIndia. Restoration Ecology 7 (3), 281–287.

Gile, L.H., 1966. Coppice dunes and the Rotura soil. Soil Science Society of AmericaProceedings 30, 657–660.

Gile, L.H., Gibbens, R.P., Lenz, J.M., 1997. The near-ubiquitous pedogenic world ofmesquite roots in an arid basin floor. Journal of Arid Environments 35, 39–58.

Goldberg, P., Macphail, R.I., 2006. Practical and Theoretical Archaeology. Blackwell,Malden.

Goudie, A.S., 1973. Duricrusts in Tropical and Sub-Tropical Landscapes. Clarendon Press,Oxford.

Goudie, A.S., 1983. Calcrete. In: Goudie, A.S., Pye, K. (Eds.), Chemical Sediments andGeomorphology. Academic Press, London, pp. 93–131.

Graf, W.L., 2002. Fluvial Processes in Dryland Rivers. Blackburn Press, New Jersey.Hackenberg, R.A., 1983. Pima and Papago ecological adaptations. In: Sturtevant, W.C.

(Ed.), Handbook of North American Indians, vol. 10. Smithsonian Institution,Washington D.C., pp. 161–177.

Heiri, O., Lotter, A.F., Lemcke, G., 2001. Loss on ignition as a method for estimatingorganic and carbonate content in sediments: reproducibility and comparability ofresults. Journal of Paleolimnology 25, 101–110.

Hodgson, J.M., 1974. Soil survey field handbook. Soil Survey Technical MonographsNo. 5. Soil Survey, Harpenden.

Konen, M.E., Jacobs, P.M., Burras, C.L., Talaga, B.J., Mason, J.A., 2002. Equations forpredicting soil organic carbon using loss-on-ignition for north central US soils. SoilSociety of America Journal 66, 1878–1881.

Machette,M.N.,1985. Calcic soils of the southwesternUnited States. In:Weide, D.L. (Ed.),Soils and Quaternary Geology of the Southwestern United States. Geological Societyof America Special Paper, vol. 203. Geological Society of America, Boulder, pp. 1–21.

Mächtle, B., Eitel, B., Kadereit, A., Unkel, I., 2006. Holocene environmental changes in thenorthern Atacama Desert, southern Peru (14°30'S) and their impact on the rise andfall of Pre-Columbian Cultures. Zeitschrift fuÉr Geomorphologie N.F. Supplemen-tary 142, 47–62.

Maizels, J.K., 1988. Palaochannels: Plio-Pleistocene raised channel systems of thewestern Sharqiyah. Journal of Oman Studies Special Report 3, 95–112.

McCauley, J.F., Breed, C.S., Grolier, M.J., 1977. Yardangs. In: Doehring, D.O. (Ed.),Geomorphology in Arid Regions. Allen and Unwin, Boston, pp. 233–269.

McKay, C.P., Friedmann, E.I., Gómez-Silva, B., Cáceres-Villanueva, L., Andersen, D.T.,Landheim, R., 2003. Temperature and moisture conditions for life in the extremearid region of the Atacama Desert: four years of observations including the El Niñoof 1997–1998. Astrobiology 3 (2), 393–406.

Mishra, A., Sharma, S.D., 2003. Leguminous trees for the restoration of degraded sodicwasteland in eastern Uttar Pradesh, India. Land Degradation and Development 14,245–261.

Moseley, M.E.,1992. The Incas and their Ancestors, the Archaeology of Peru. Thames andHudson, London.

Moseley, M.E., Feldman, R.A., Ortloff, C.R., Narvaez, A., 1983. Principles of agrariancollapse in the Cordillera Negra, Peru. Annals of Carnegie Museum 52 (13),299–327.

Munsell, 2000. Munsell Soil Colour Charts. Gretag Macbeth, New York.Murphy, C.P., 1986. Thin Section Preparation of Soils and Sediments. AB Academic

Publishers, Berkhamsted.Nabhan, G.P., 1986. Papago Indian desert agriculture and water control in the Sonoran

Desert, 1697–1934. Applied Geography 6, 43–59.ONERN,1971. Inventario, Evalacíon y Uso Regional de los Recursos Naturales de la Costa.

Cuenca del Rio Ica, vols. 1 & 2. Oficina Nacional de Evaluacíon de Recursos Naturales(ONERN), Lima.

Pasiecznik, N.M., Felker, P., Harris, P.J.C., Harsh, L.N., Cruz, G., Tewari, J.C., Cadoret, K.,Maldonado, L.J., 2001. The Prosopis juliflora– Prosopis pallida Complex: aMonograph.HDRA, Coventry.

Parker Gay Jr., S., 1999. Observations regarding the movement of barchan sand dunes inthe Nazca to Tanaca area of Southern Peru. Geomorphology 77, 279–293.

Petrov, M.P., 1976. Deserts of the World. John Wiley & Sons, New York.Raghavan, R., Gaillard, C., Rajaguru, S.N., 1991. Genesis of calcretes from the calc-pan site

of Singi Talav near Didwana, Rajasthan, India: a micromorphological approach.Geoarchaeology 6, 151–168.

Schlesinger, W.H., 1985. The formation of caliche in soils of the Mojave Desert,California. Geochimica et Cosmochimica Acta 49, 57–66.

Schulte, E.E., Hopkins, B.G., 1996. Estimation of organic matter by weight loss-on-ignition. In: Magdoff, F.R., Tabatabai, M.A., Hanlon, E.A. (Eds.), Soil Organic Matter:Analysis and Interpretation. Soil Science Society of America Special Publication,vol. 46. SSSA, Madison, pp. 21–31.

Schumm, S.A., 2003. The Fluvial System. Blackburn Press, New Jersey.SENAMHI-Ica, 1997. Boletine Meteorológico. Servicio Nacional de Meteorología e

Hidrología, Ica.SENAMHI-Ica, 2002. Boletine Meteorológico. Servicio Nacional de Meteorología e

Hidrología, Ica.Shimada, I., Schaaf, C.B., Thompsonm, L.G., Mosely-Thompson, E., 1991. Cultural impacts

of severe droughts in the prehistoric Andes: application of a 1,500-year ice coreprecipitation record. World Archaeology 22, 247–265.

Silverman, H., Proulx, D.A., 2002. The Nazca. Peoples of the America Series. BlackwellPublishers, Oxford.

Stone, E.L., Kalisz, P.J., 1991. On the maximum extent of tree roots. Forest Ecology andManagement 46, 59–102.

Thompson, L.G., Mosely-Thompson, E., Bolzan, J.F., Koci, B.R., 1985. A 1,500-year recordof tropical precipitation in ice cores from the Quelccaya Ice Cap, Peru. Science 229,971–973.

Wells, L.E., Noller, J.S., 1999. Holocene coevolution of the physical landscape and humansettlement in northern coastal Peru. Geoarchaeology 14 (8), 755–789.

http://www.arch.cam.ac.uk/dgb27/

Linking cultural and environmental change in Peruvian prehistory: Geomorphological survey of th.....Introduction and area of studyMethodsResultsBasic geomorphic unitsSection 1/013 — relict terrace H-13Survey Pit 1/030 — buried land surface and buried soilSurvey Pit 1/031 — gradual aeolian deposition

Discussion and conclusionsAcknowledgementsReferences

Linking cultural and environmental change in Peruvian ......Linking cultural and environmental...

Documents

Transcript of Linking cultural and environmental change in Peruvian ......Linking cultural and environmental...