MASON RANCH

FAIRFIELD, CALIFORNIA

FAULT INVESTIGATION

•

•

•

EN GEO INCORPORATED

July 25, 1978

Hofmann Company 1035 Detroit Avenue P. 0. Box 907 Concord, California 94522

GEOTECHNICAL & ENVIRONMENTAL CONSULTANTS

In Reply Please Refer to:

NS-1270-Bl

• Attention: Al Shaw

•

•

•

•

•

•

•

Subject:

Gentlemen:

Mason Ranch Fairfield, California

FAULT INVESTIGATION

As requested, we have completed an investigation of the subject property with respect to the Cordelia Fault .

The accompanying report presents our conclusions and recommenda­tions, as well as the results of the investigation. We find no evidence of an active fault crossing the subject site, and con­sider development feasible from a geologic viewpoint.

We are pleased to have been of service to you on this project . If you have any questions, please call us.

Very truly yours,

E:;~n~ ~ . William B. Wig~~ C.E.G. #855 ffi~~ --Copies: 4 to Client

• 2280 DIAMOND BLVD. • SUITE 200 • CONCORD, CALIFORNIA 94520-5719 • (415) 687-9700 • FAX (415) 687-0126

•

•

•

•

•

•

•

•

•

•

•

REPORT

to

HOFMANN COMPANY

on

FAULT INVESTIGATION

of

MASON RANCH

FAIRFIELD, CALIFORNIA

ENGEO PROJECT NO . NS-1270-Bl

JULY 25, 1978

•

•

•

•

•

•

•

•

•

•

• ENGEO INCORPORATED

TABLE OF CONTENTS

INTRODUCTION Purpose ..................................... . Scope .................................... · · · · Methods of Investigation .................... . Site Location and Description ............... .

FAULT INVESTIGATION Seismic Setting ............................. . Nearby Investigations ....................... . Previous Investigations ..................... . Aerial Photograph Interpretation ............ . Trench Excavation ........................... . Geologic Reconnaissance ..................... .

CONCLUSIONS ...................................... . RECOMMENDATIONS .................................. . .LIMITATIONS ...................................... . SELECTED REFERENCES .............................. .

APPENDIX

Page

1 1 1 2

3 3 4 5 5 6 8 9

10 11-12

Figure 1 Figure 2 Figure 3

Site Location.. . . . . . . . . . . . . . . . . . . . . . . . . . 13 Geologic Map . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Alquist-Priolo Map (1974) . . . . . . . . . . . . . . 15 Fault Map and Quote .................... 16 Figure 4

Figure 4a Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Air Photo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Site Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Interpreted Max. Bedrock Accelerations .. 20 Trench Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Q

•

•

•

•

•

•

•

•

•

•

•

INTRODUCTION

Purpose

The purpose of this investigation is to locate and define any seismic hazards that may exist which could preclude development

of this site as planned. Previous mapping by Helley and Herd (1977)

indicates that the site may be crossed by the Cordelia Fault .

Study followed the Suggested Guidelines for Evaluating the Hazard

of Surface Fault Rupture, Note No. 49, published by the California Division of Mines and Geology .

Scope

1) To locate the Cordelia Fault if present on site, and determine its fault activity and potential for ground rupture.

2) To make comment on hazardous geologic or seismic conditions,

if any, uncovered as part of this investigation .

Methods of Investigation

Investigation procedures consisted of a careful review of geological

reports and maps involving the area, interpretation of aerial

photographs covering the site and its vicinity, a geological reconnaissance, and trench excavation. Geophysical work was conducted, but irregular readings resulted from the agglomeratic lithology of the volcanic bedrock .

EN GEO INCORPORATED

©

•

• Site Location and Description The site is located north of the intersection of Highway 680 and

Interstate 80, along Green Valley Road, near Cordelia, California

• (see Figure 1). It has been proposed that the approximately 400 acres of land be developed into a combination of single and multiple

family residences, with an accompanying school, shopping center

•

•

•

•

•

•

•

•

and park I open space area .

Topography in the northern portion of the site consists of hills ·

rising to 550' in elevation, covered with a vegetation of oaks and

annual grasses. The southern portion of the site contains pasture­

land, some of which is irrigated. A Pacific Gas and Electric right­

of-way crosses the property with a northeasterly trend, and the

concrete lined Putah South Canal crosses the property in the middle,

trending easterly (see Figure 6). A single family residence (the Mason Ranch house) presently exists in the mid-western portion of

the site.

According to Sims, et al (1973) (Figure 2), the northern upland portion of the site is underlain by rocks of Tertiary age, belonging

to the Sonoma Volcanic Group. These rocks are composed of andesitic

to basaltic lavas, with some rhylotic lava. Ashflow tuff, locally

welded together with bedded agglomerate and tuff breccia or pumicitic tuff, also occurs. Outcrops of these rocks occur throughout the northern portion of the site. Good exposures of the ashflow tuffs

may be seen in the canal cuts .

The southern portion of the site is underlain by Quaternary alluvial

sediments derived from erosion of the volcanic upland areas .

ENGEO INCORPORATED

®

•

• RAULT INVESTIGATION

e Seismic Setting

The Green Valley fault is the major active fault in the site vicinity.

A main trace of this fault is mapped within 3500' to the west of the e site (Figure 3). The Green Valley fault is considered active by the

U.S.G.S., being a possible northward continuation of the Concord fault

which is known to be active. The State Division of Mines considers it

active within Quaternary time (last 2 million years) under the pro-

• visions of the Alquist-Priolo Act (see Figure 3).

A Cordelia fault has recently been mapped by Helley and Herd (1977),

as passing through the easternmost portions of the site. Previous

• mapping did not recognize the Cordelia fault, which was mapped in its present location based upon lineaments of possibly fault related topo­

graphic features (see Figures 4 and 4a), and limited field work.

• Nearby Investigations

•

•

•

•

A geological investigation on the Mangels Ranch property, adjacent and

south of the site, was completed in March 1978. Approximately 290'

of trenching across the mapped trace of the Cordelia Fault revealed

no active faulting. A seismic refraction survey, performed by Louke and Associates, likewise revealed no indications of faulting.

Seismic Traverse No. 1 was 500+ feet in length and located 300! feet

south of the southern Mason Ranch boundary.

To the north, Applied Soil Mechanics (July 1978) studied the Anderson

Ranch property with respect to hazards posed by the Cordelia Fault . Detailed field mapping of Anderson Ranch, and logging of roadcuts along Rockville Road, lead them to conclude that no active fault traces

ENGEO INCORPORATED

•

•

•

•

•

•

•

•

•

•

•

cross the Anderson Ranch in the mapped location of the Cordelia Fault,

or anywhere else. Faulting exposed along Rockville Road was determined

to have occurred because of diapiric folding and not to be presently active or laterally extensive. An unfaulted, continuous layer of

volcanic rock has been deposited across the fault trace as mapped south

of Rockville Road. This indicates that no movement has taken place since the volcanic layer was deposited 5 to 25 million years ago.

Previous Investigations

A Preliminary Draft EIR investigation was done of the site by

Larry Seeman Associates (1978). The investigation revealed areas

of anomalous topography in the northeastern portion of the site

which are suggestive of landslide processes. Figure 9 shows these landslide prone areas along with site geology. ENGEO field checked the site geology and basically concurs with the findings in respect to contacts between lithologies and stability ratings .

ENGEO INCORPORATED

©

•

•

•

•

•

•

•

•

•

•

•

Aerial Photograph Interpretation

The following stereo black and white aerial photographs were studied as part of this investigation:

Flight Line Year Scale Source

AV-844-15-14 1968 1:30,000 Pacific Aerial Surveys AV-844-15-15 1968 1:30,000 Pacific Aerial Surveys AB0-52-41 1937 1:20,000 u. c. Berkeley AB0-52-42 1937 1:20,000 u. C. Berkeley AB0-52-43 1937 1:20,000 u. C. Berkeley AB0-54-44 1937 1:20,000 u . c. Berkeley

The photographs were scrutinized for the presence of terrain features

characteristic of fault zones, such as linear discontinuities in rock

or soil, offset water courses, linear scarps, topographic lows, or

breaks in slope. Several such lineations are apparent, mainly as breaks in slope, and linear valleys with vegetation contrasts (see

Figure 5). The most noticeable is a line of vegetation contrasts

and breaks in slope corresponding to the mapped Green Valley fault

location. A line of lighter coloration, generally lacking vegetation,

crosses the site in the mapped Cordelia fault location. Most other

features used by Helley & Herd (1977a) to delineate the Cordelia fault are also discernible. These lineaments were field checked

during our geologic field reconnaissance, and found to be unrelated to fault activity.

Trench Excavation

A 180~ foot long trench was excavated across the mapped trace of the

Cordelia fault in the southeastern portion of the site (see Figure 6).

The trench revealed the subsurface.contact between volcanic bedrock

and alluvium (see Figure 8). Fractured light green tuffaceous bedrock was found between Stations 0+00 and 0+72, with a bedding attitude of approximately N8W, 41W. This bedrock dipped gradually to the west,

ENGEO INCORPORATED

•

e as did the ground surface. At Station 0+53, a series of interfingered sediments began and continued for the remainder of the trench. Water

seepage occurred and stabilized at approximately 5 feet below the soil

surface. No bedding offsets, slickensides, shear zones, or other

• fault indicative features were evident in any part of the trench.

Trenching was attempted across the mapped fault trace in the northern portion of the site, but refusal in tuffaceous bedrock was encountered at

• a depth of less than 1 foot below soil surface. No fracture zones or offsets of the surface soil could be detected in the 80' of bedrock

exposed by this attempted trenching .

•

•

•

•

•

•

•

Geologic Reconnaissance

The eastern portions of the site, including the Putah South Canal,

were examined for evidence of active fault movement. No such evi­

dence was found. No cracks or offsets are noticeable in the concrete lining of the Canal. Only minor iron stained fractures occur in the

exposed tuffs. The general attitude of these fractures measures N6W, 67°E. A contact between a white lithic tuff bed to the north,

and an agglomeritic flow to the south, is located near the intersection

of the mapped fault trace and the Canal. The contact is gradational,

and no shearing is evident. One slickensided fracture surface with

an attitude of N22W, 73°E, is noticeable along the Canal cut approxi­mately 700' west of the mapped fault trace. No offset of surface soil

is apparent.

Field checking of air photo lineaments revealed topographic features capable of being formed by a variety of geomorphic processes. The linear

valleys or troughs occur on less resistant tuffaceous beds paralleled on both the east and west sides by "scarps" or outcrops of the more re­

sistant andesitic and ba.sal tic flow rocks, which appeared to be conformable .

Fault exposures are evident in roadcuts along Rockville Road. The most

ENGEO INCORPORATED

®

•

• noticeable is 0.6 miles north of the site, on line with the mapped

Cordelia fault trace. It is characterized by a highly sheared gray

• lithic tuff with reddish slickensided surfaces measuring NSE, 82E.

According to Helley & Herd (1977a), this fault exposure cuts '"'A"

horizon soils, indicating recent activity (Figure 4a). Such surface soil offset was not in evidence at the time of ENGEO's reconnaissance,

• and as previously mentioned, Applied Soil Mechanics reports the faulting as not active, based on their inspection of this exposure .

•

•

•

•

•

•

• EN GEO INCORPORATED

•

•

•

•

•

•

•

•

•

•

•

CONCLUSIONS

l) The results of exploratory trenching and field work by ENGEO show

the site to be free of active faulting. Air photo lineations used

by Helley and Herd (1977) to map a "Cordelia Fault" across the east­

ern portions of the site are unrelated to fault activity, but caused

by differential erosion. Studies done on these lineations both to the

north (Anderson Ranch) and south (Mangels Ranch) of the site also

show them to be unrelated to faulting. Because of the above, the po­

tential for ground rupture on-site is considered remote .

2) Secondary seismic hazards pertinent to the proposed development

include ground shaking, landsliding and liquefaction. Ground shaking

can be expected during the life of the structures. Historic earth­quakes have most likely generated maximum accelerations on the order of 0.2 g (see Figure 7) which can be mitigated by current code prac­being utilized for the residences.

Trenching revealed a high ground water level and the presence of gran­

ular soils in the southern pastureland portion of the site. The lique

faction potential of this area should be further investigated.in the soil investigation phase. Liquefaction was not considered a serious

concern on the adjacent Mangels or Anderson Ranches .

Seismically induced landsliding is a potential hazard in the northern

portions of the site, particularly those mapped as landslide prone

areas in the Environmental Impact Report by Larry Seeman Associates

(1978). These can be mitigated by proper engineering design. The

majority of the unstable ground is in future open areas. The detailed

soil investigation should study these areas which encroach into the

development area to make appropriate recommendations for stabiliza­

tion.

EN GEO INCORPORATED

•

•

•

•

•

•

•

•

•

•

•

RECOMMENDATIONS

1) We see no need for additional geologic studies, except for a

future geologic update investigation at the time of school planning.

2) As an active fault was not found to traverse the site, no set­

backs are deemed necessary.

3) A detailed soil and foundation investigation should be conducted

on-site with particular attention paid to liquefaction potential and

potential landsliding.

4) Trenching has been loosely backfilled. Its position should be

precisely located so that further attention can be given to its

effect on planned improvements.

5) Current U.B.C. seismic design practices should be used as a mini­

mum requirement for structural design of residences .

ENGEO INCORPORATED

•

•

• LIMITATIONS

This report is based upon data obtained by surface reconnaissance, subsurface exploration by trenching, interpretation of aerial

photographs and review of geologic maps and literature pertinent to

the site. No inference should be drawn from the language of the

e report that the scope of the investigation was any wider. It must

•

be understood that although the observed and reported conditions

are considered representative, local variations of geologic conditions

may exist for which this firm cannot assume responsibility .

No warranty as to the contents of this report is intended and none shall be inferred from the statements or opinions expressed. This

report was prepared upon your request for our services and in accord-

• ance with accepted standards of professional practice. The transmittal of this report to you completes our contract requirements .

•

•

•

•

• ENGEO INCORPORATED

•

•

•

•

•

•

•

•

•

SELECTED REFERENCES

1. Borcherdt, R.D., 1975, Studies for Seismic Zonation of the San Francisco Bay Region, U.S.G.S. Professional Paper 941-A.

2. Brown, R.P., 1970, Faults that are historically active or that show evidence of geologically young surface displacements, San Francisco Bay region; A progress report, U.S.G.S. MF-331 .

3. California Division of Mines and Geology, 1974, State of Cali­fornia Special Studies Zones, Cordelia Quadrangle.

4. Del Davis Associates, Inc., 1977, EIR for Mangels Ranch Planned Development, City of Fairfield, California .

5. Dooley, R.L., 1973, Geology and land use considerations in the vicinity of the Green Valley fault, Solano County, California: California Univ. Davis, unpub. M.S. thesis.

6. ENGEO, Inc., 1977, Soil and Geologic Data for EIR of 1400 acres in Brown's Valley Area, Vacaville, California.

7. Frizzell, Brown, 1976, Map Showing Recently Active Breaks along the Green Valley Fault, Napa and Solano Counties, California, U.S.G.S. MF-743 .

8. Geomechanics, 1972, Feasibility Study for Mangels Property, Fairfield, California.

9. Geomechanics, Inc., 1978, Geologic Investigation for Mangels Ranch, Cordelia, California,

10. Helley, E.J., Herd, D.G., 1977, Map Showing Faults with Quaternary Displacement, Northeastern San Francisco Bay Region, California, U.S.G.S. MF-881.

11. Helley, E.J., Herd, D.G., 1977(a), Field Observations and Air Photo Interpretation Map, Scale 1:24000, unpublished .

12. Jennings, 1975, Fault Map of California, C.D.M.G. Geological Data Map ffl.

13. Larry Seeman Associates, 1978, Preliminary Draft EIR for Hofmann e Property, Cordelia, California.

•

14. Sedway/Cooke, 1976, Health and Safety Final Draft, County of Solano.

EN GEO INCORPORATED

@

•

•

• 15. Sims, Fox, Bartow, Helley, 1973, Preliminary Geologic Map of

Solano County and Parts of Napa, Contra Costa, Marin and Yolo Counties, California, U.S.G.S. MF-484 .

16. U.S.G.S., 1951, 7.5 Minute Topographic Map Series, Cordelia Quadrangle.

17. Applied Soil Mechanics, July 1978, Geologic and Seismic Hazards • Investigation of Anderson Ranch, Solano County, California,

•

•

•

•

•

•

• EN GEO INCORPORATED

•

•

• APPENDIX

Figure 1 Site Location

Figure 2 Geologic Map

• Figure 3 Alquist-Priolo Map (1974)

Figure 4 Fault Map and Quote

Figure 4a Observations

Figure 5 Air Photo

• Figure 6 Site Plan

Figure 7 Interpreted Max. Bedrock Accelerations

Figure 8 Trench Log

Figure 9 Geology

•

•

•

•

•

• EN GEO INCORPORATED

•

•

•

•

•

•

•

•

•

•

•

-· ····· -····

SOLANO COUNTY

COll/lll,INIT'I cou..tOE

App Man

Invest±

.. . •

oximate els Ranch ation Bounda

SCALE

~~·o~oo~-•o-~~-•-•o-•~·-•~~~•_,n~•~ Ot 0.2 01 0<0 0.111 o• 01 oa o~ 10-.i:

ENGEO Mason Ranch · Fairfield, CA

_ .. --· --··

·-.:

/

IN COR p OR ATE D 1-=-:~--sr_T_E_L_oc_A.....,Trr-o_N -------1 ~SC,.-A_L_E--=G~i~v~e~n.__ ___ ~~---1JOB ENGINEERS ANO GEOLOGISTS

CONSULTANTS IN THE APPLIED EARTH SCIENCES DATE Jul 1978 NO. NS-1270-Bl

\

'

I

FIGURE NO.

1

2150 SHATTUCK AVENUE, SUITE 400,BERKELEY, CALIFORNIA 94704 · PHONE (415) 548-8800

•

•

•

•

•

•

•

•

•

•

•

.v .-:. -·· -

T"

Tsr'i

Tsrp

Tsa

Tsai

Tst

Tswt

SONOMA VOLCANICS

SONOMA VOLCANICS, UNDIVIDED

RHY~~~!{fy~AVA FLOWS -- contains intercalated rnyolitic tuff locally. Intraformational contacts shown

INTRLSIVE RHYOLITIC ROCKS -- includes plugs and dikes. Hay be in part extrusive,

RHYOLITIC ANO PERLITIC FLOWS AND PLUGS

ANDES IT IC TO BASAL TIC LAVA FLOWS

ANOESITIC TO DACITIC PU.:'GS OR INTRL1SIV£ CO!-!PLEX -- area of abundant small plugs or dikes not separately mapped.

ASH-FLOW TUF~S.-- pumiciti:, local!y welded or partly welded with intercalated bedded aoglor.eritic tuff and andes1t1c or basalt1c lava r1ows, bedded tuff, oumicitic tuff. Intrafonnational.con~acts shown locally -

ASH:..FL-OW TUFF -- partly welded.

Mason Ranch Fairfield, CA.

<'

' ) . I"'/\, <.. I I

·. \ .... r-~--1 I

N

FIGURE NO. EN GEO

GEOLOGIC MAP from Sims, al. (1973) 2

INCORPORATED et

ENGINEERS ANO GEOLOGISTS SCALE JOB CONSULTANTS IN THE APPLIED DATE Jul NO. NS-1270-Bl EARTH SCIENCES

2150 SHATTUCK AVENUE, SUITE 400,BERKELEY, CALIFORNIA 94704 PHONE (415) 548-8800

•

•

•

•

•

•

•

•

•

•

•

Alquist-Priolo Boundarv for Green Valley Fault Zone

EN GEO Mason Ranch Fairfield, CA

I NCO R p OR AT ED 1-=::-:,..,.A-=-LQ_u_rs_r_-P_R_r_oL_o_M_!AP-.,.-(_1_97_4_) -------l SCALE 1:24000 JOB ENGINEERS ANO GEOLOGISTS

CONSULTANTS IN THE APPLIED EARTH SCIENCES

1-'o""A""T.:.:E==--J u""1...=-:""'1"'"9~7'--3----I NO. N 8- 12 7 0- B 1

s u ~

I

FIGURE NO.

3

2150 SHATTUCK AVENUE, SUITE 400, BERKELEY, CALIFORNIA 94704 · PHONE (415) 548·8800

•

•

•

•

•

•

•

•

•

•

•

-~ - :,"-;..____ ""'t>

!~-, __ .. ~]~ r

'"' ' I

I~· ' c I r I

/1·,., /

L

~

t~ ~ !'~~:~~~":~~ion .. : · ..

'

. ' ' .

The Cordelia fault zone is named for a small village between State Highway 21 and Interstate 80 northwest 9f Suisun Bay. This fault lies only a few kilometers east of the Green Valley fault and may represent a branch of it. The fault was first recognized just south of Cordelia as a linear contact between soils developed on Holocene basin deposits on the west and older alluvial fan deposits on the east, with the older soils anomalously on the downslope side. This contact also appears to be a ground-water barrier as shm.rn by a near-surface wet zone. Photolineaments allow extension of the fault north of Corde!ia into the bedrock hills underlain by the Sonoma Volcanics. Approxi­mately 3 km north of Interstate 80, the fault splays into a series of four or more traces, each marked by vegetation lineaments, scarps, linear troughs, notches, and shutter ridges. The zone there is about 2 km wide. The fault zone narrows northward but can be traced by a few scarps, photolineaments and vegetation lineaments to the western shore of Lake Curry. No evidence for young fault~ng was seen in the alluvium in Wragg Canyon, a linear valley extending to the southeastern end of Lake Berryessa 'along the projected strike of the Cordelia fault. The east side of Lake Berryessa shows some features of young faulting. Here, shutter ridges and alinements of notches, saddles, and closed depressions are common.

Some earthquakes attributed to the active Green Valley fault by Frizzell and Brown (1976) may, in fact, originate on the Cordelia fault. Where exposed in new roadcuts, the Cordelia fault appears to displace A horizons on soils formed on the Sonoma Volcanics. Sense of :notion is right-lateral strike-slip, and all slickensides observed to date have been horizontal.

·1

'

ENGEO FIG~UOR. E Mason Ranch Fairfield, CA.

J NC QR p QR ATE O 1-:F:-::-a-:-u:-:l:'"'.t :-M...,.a-:-p-,-a_n_d_Qu_o_t_e--.-fr_o_m_H_e_l_l_ey;:__&_H_er_d __ rl 9 7 7) ENGINEERS ANO GEOLOGISTS SCALE 1: 125000 JOB coNsu~;::~~;';'s~ li:JE~••L1Eo t-:0::-::A:-::T::E::-"'J:-u'-':'l=-,1~9-=7:-:8:-----t NO. NS-127o-B1

2150 SHATTUCK AVENUE, SUITE 400,BERKELEY, CALIFORNIA 94704 PHONE (415) 548-8800

•

•

•

•

•

•

•

•

•

•

•

~·

, .

·'f

EAST FACING SCARP

ENGEO Mason Ranch Fairfield, CA .

Observations of Helley & Herd 1977(a) INCORPORATED~~~~~~~~~~--i

ENGINEERS ANO GEOL..OGISTS CONSULTANTS IN TME APPL.I ED

EARTM SCIENCES

SCALE 1: 24000 JOB r.D~A~T~E=---J~u~l,......~1~9~7~8~----jNO. NB-1270-Bl

., "·

FIGURE NO.

4a

2150 SHATTUCK AVENUE, SUITE 400,BERKELEY, CALIFORNIA 94704 · PHONE (415) 548·8800

•

•

•

•

•

•

•

•

•

•

•

Lineations observable on air photo

ENGINEERS ANO GEOLOGISTS CONSUL TAN TS IN TME APPLIED

EARTH SCIENCES

2150 SHATTt;CK AVENUE, SUITE 400,BERKELEY, CALIFORNIA 94704

FIGURE NO .

5

PHONE (415) 548-8800

... ' -

"' ... .. .. .. 0 0

• •

.,, ZG'l

°' oc . :n m

• •

., t,.,,,,,)"'..u

'J'"'"'""" v;.&

\ \ I I

.. :,- ' ' I •• • . . .. . .':. : .. . '• - ·.·.·. :'.•'

TI

• • • • • u

, .

_\,,_ -­

__ 1·

•

•

•

CD

0 ..... d

CD

d U'> V I") N d d d d d 0

6 - uo,,0Jap1:>:>'f wnwpcow

ENGEO Mason Ranch Fairfield, CA.

INCORPORATED INTERPRETED MAX. BEDROCK ACCELERATIONS ENGINEERS ANO GEOLOGISTS

CONSULTANTS IN THE APPLIED EARTH SCIENCES

SCALE none JOB DATE Julv 1978 NO. NS-1270-Bl

FIGURE' NO.

7

2150 SHATIUCK AVENUE, SUITE 600, BERKELEY, CALIFORNIA 94704 • PHONE (415) HS-880

• ~

•

•

•

•

•

•

•

~ •

•

•

. GEOLOGIC UNITS

i

~[1>. : . ! ij

Qol - Alluvium ·-,_

~sr - Rhyolitic ICMJ flows

Tso - Andesitlc to bosottic lava flows

Tst - Ash· flow tuffs

Tswt - Ash-flow tuff, portly welded

.·

.,, + ~

J -~-

• '15 . . ~

r I 11 ~ ·ti a l!'l §: ! {~ ~ it ; ,. ~l; s! .l! ... ~- - 0 5 "-=Iii·· ~. l a!2!1 .f2f ·1- "Z .I "1 ! ~ i t"' i '6 ·c o-k • 1

.2 en -a 1 ~ en !!!.J \ J ... \ r:.1 _ =·-~ \ ... --

·· .... . =

('1 \.)

I :!: i: l --; J! II~ • .. -

- 0 ~~ -;; a ~Ii. 0 ... A. 0

\ ' \

---·- -- --------=-~ -------· ·--·-- --·-.

I\ . \. \ . ,\. + 1 · .. ,,.

\\ . · ... /

~ -y··· '··.

;; - ) I" ~-"\_ -- . ..# /· ', / ./ i I · .. f ./ ·/ . . \,

. T i re i ..

I ' 0 ' . · . .{- : . . ,._

! . -1'.

;'+· ' . .

'

b -. ! . ----·- ----.. _--: -; - : -

- . ~,'--: _..::. -

--n - . ..:....· ____ /: // / :f / " ' .. . .. ' .. . ~. ,: " ,'

I I .

. .-,1'· .. ..

\ \. .... \\

·\\~./ .,,_; 0~ . .,, ~~ t~~ SCALE ~ __ ,;:;~,. {{ . 0 400 100

I

j :Mason Ranch / Fairfield, CA EN GEO

. - - ... _. \

. ..:..; . :• .- ~

FIGURE NO.

INCORPORATED Geolop;y ''after Larry Seeman Assoc. (1978) 9 ENGINEERS ANO GEOLOGISTS SCALE JOB

CONSULTANTSINTMEAPPLIEO DATE 8 NO NS-1270-Bl EAR:TM SCIENCES •

2150 SHATTUCK AVENUE. SUITE 400, BERKELEY, CALIFORNIA 94704 •

PHONE (415) 548-8800

!

•

•

•

•

•

•

•

•

•

•

O'

5'

O'

5 '

O'

5 '

EAST

0 U"\ + ,.....

I I

I I I I I I

I I

I I

I ' I I I I I I

' •I '.

" I I

I I

\

I I

I

' I

s1 rf.ace

I I

I

'

I I ' I

I I I I I 0 I ~ •

I I I I

I I I I I 1

I I I I I

I I I

"

I I

I I

I I I I

I ' I '

I I I

I

I I

I I I I I

' ' ' ' '

' ' '

I I I

I I • i 'I I

I I , I

' ' I I I i I I I I I I ,...,....,. I

I I i

I I I I 1--,-1 I I I I I

I I I I I I

,, ''

I I I I I I

I I I

I I I I I

I I I I I I I I I

I

' I I I I

" " I I l .J. JJ

I I , <> I

I I

"

I I I I I I I I II

I I ' • I

I I

I

' I

I ,• I"! I

,---- - ~,·-,---

• 1 I I

I I

' ' ' I I I I I I I I I

I I I I I I I

I

' I

I I I

I I I I

I I I

I I I I

I

' ' I

I I I I

I I I

I I

I I I I I I

I I I ! I I I I #

I ' '

I ' '

I I I I ' I I ;

I I I : I I I I I I I I

I I I I I I I I I I I I I

I I ' I I I I I I I I I I I ! I I I I I I I I I I I

' I I I I ~ .. , I,; I . ' I I I ! .... ,,

I I

I I I I -1 I ·'

I I I

I I I I I

I I

'

I I I I ·, I I I' I ' I I

< I ' I I . ., .. , I ' I I I I I I I I I I I I I I I I I I I I I I I I

1 I I I i I I

I I ! I I I I I I I i I I I I I I I

I•

I I

I ' '

I I I I I I I I I I I I I I

I

I

~

I

I tlt. IJ'lo II

I I I I I I I I I I I I

I I

' l l L.l~I l L I L I I I _l l .. L U"\ 0 U"\ "' + + ,..... ,.....

I i TT i I 111 Q I I

I i I I 1 I I I I I I ! I I

' ' ' I I

I I

I 1~1

I I I

., ·I•

I

' ' .

Pl

~

co + ,.....

SOUTH WALL

I- I I .. I

'

' ' I •I

• 1 ' I I

I I I I

I I I

I '

I

I I I

I I

I I I

'

.,

..--r -

I I I

I

I I

'' 'I'

' I I

I I I

'I I I I

I I I I I

I I

I • .1 I

I I

: ! ~' : I I I I' I

I

~ I '

I I 1 I I I I I I I I I I I I I I

I

I I

' I I I

I

I I I I I

I

I

' I i

"

I I

I

I ;1 , I 'I 1 I I , I I! I

L 1. •• I I I I. '- - --

I

' I I

! I

I I I I I I I

I I I I i I I I ' I

I I ' I I

I I I I I I I I I I

I I

I

'

I

' I I

'

r r , ••

' I

! ! !

I

' ' I

' I

' I I I

I

I T ' ' 1 I '

I I I I I ' I

1~ I I I 1. I ! ::;,1_t

' '

I I I I ! I I I f ~ i I I I

' ' ' : I I I

" !

' I

' I I '\ ' I : I I

I I ' 1 1 I

I I I I I I ; I I I

I I I ! I I I I ,

I I + I I I I

I I I I I I I I I

,.

I I I I

" . - -r ......

' I I

I I

I I

I I I I I I I I I I I I I

I I I t I !/"1 I

I I I \ I I I

I I I I ' I I I I

' ' ' 1t'Z: ' ......

' I '

I I I

I " I

' ' ' I

I I I I I I I I

I I

I I 'I I 'I I

I I

' I I

I I I

'

I I I ' I I

I I I I

I I I I I ! I I I I

I I I I I

I I I .')

i I I I I I I I

I

I I i

.I

• I I 1 I I I Ii

: ."' ! -' I I I I ~

' i i ' I I I I I I

I I I I I ' I I I

'· I I I 1 I I I I

' I I I I I I I

' I ' I I I I I I

I. I I I I I I !\ I 1 I• I I I I .I 1 I I i "I I I I ., I _•I I I

I I I I I I I I

·,·,~,~.~' ,. I I I I

.'~'· I . ' I

I ' ~

I I

I i ~ l't

' I I

I•

' ' I I I ' I ' I I

I i

I I ! I I

! I I I ; I I

I I I

' +

I 1 I I I I

I I I

'

1 I I I le

I I

' I

' I I

I I I I I I , : I I I I 1 I I I i ' I I I I I ! I I I 1 i I I ' I I ' I I 1~·

' +

! I I I I I I I I

l<.:1 I

I I ' , I I I , I I I

I I i I ' I I I I I I

' I I

, ' I I I I I

I I ' ' '

I I I I I I I I

I I I

....--- Water Seepage

I I I

I I I .:J-" I

' I ' I

\ ' I I I I I I I

I I ' I I I I

.I 1 I I I

.I I I I I I

, I

+' '

I

I I

I I

.. I

' ' I I I I I

' I I

I I I I I I

I I I I I

I I I i I I I I I I I I

... ! I I I I I

+

11\\\\1 I:-=--:-~

Fractured light gree~' tuffaceous rock; red weathered surfaces some brown-gray. siltyj clay c~llected in crevasses. Bedding , - ·· NSW, 41W Gray sandy clay with :lithic fragments, moist, med. stiff.

l I . ,\ : ·\. I I ·.· · ·: · ·: I ; .~ ... ..

Red weathered lithic sand, grading to moist, dense - very dense.

Fine dark gravel wet· dense.

ENGEO Mason Ranch Fairfield, CA

yellowish towards west,

FIGURE NO.

IN co R p 0 RATED 1------'-'FRE_NC_H_L_OG_..----------4 ~SC~A~L~E~-+~~~~~---1JOB

8

ENGINEERS ANO GEOLOGISTS CONSULTANTS IN Tl-IE AF>Jll..IED

EARTM SCIENCES DATE Jul 1978 NO. NS-1270-Bl

2150 SHATTIJCK AVENUE, SUITE 400, BER ELEY, CALIFORNIA 94704 PHONE (415) 548-8800