Petrology of Sediments 

Underlying Areas of 

Land Subsidence in 

Central California 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 497-C 

Petrology of Sediments 

Underlying Areas of 

Land Subsidence in 

Central California 

By ROBERT H. MEADE 

MECHANICS OF AQUIFER SYSTEMS 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 497-C 

With emphasis on the petrologic characteristics 

that influence the compaction behavior of the 

sediments: particle size, clay minerals, and 

associated ions 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEW ART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 65 cents ~paper cover) 
CONTENTS 

Abstract __________________________________________ _ 

Introduction ______________________________________ _ 

Purposes of report _____________________________ _ 

Collection of samples ___________________________ _ 

Acknowledgments ______________________________ _ 

Sediments in the Los Banos-Kettleman City area ______ _ 

Sources of sediments ___________________________ _ 

Source criteria _____________________________ _ 

Andesitic sands ____________________________ _ 

Types of deposits ______________________________ _ 

Criteria for distinguishing principal types of 

deposits ________________________________ _ 

Large-scale criteria _____________________ _ 

Textural evidence of processes of deposition 

in fine-grained sediments ______________ _ 

Alluvial-fan deposits _______________________ _ 

Flood-plain deposits ________________________ _ 

Lacustrine deposits ________________________ _ 

Deltaic deposits ___________________________ _ 

Particle sizes __________________________________ _ 

Particle-size distributions of recovered sediments __________________________________ _ 

Spatial distribution of particle sizes __________ _ 

Relations between particle-size measures and 

their bearing on the depositional history of 

sediments _______________________________ _ 

Review of previous work ________________ _ 

Relations of average particle size to 

sorting and skewness _____________ _ 

CM diagrams _____________________ _ 

Interrelations of particle-size measures in 

cored sediments _____________________ _ 

Flood-plain sediments ______________ _ 

Alluvial-fan sediments ______________ _ 

Clay minerals and associated ions ________________ _ 

Clay minerals and their assemblages _________ _ 

Sources of clay minerals ____________________ _ 

Sources of montmorillonite ______________ _ 

Sources of other clay minerals ___________ _ 

Total clay-mineral content of sediments ______ _ 

Ions associated with clay minerals ___________ _ 

Exchangeable cations in modern stream 

sediments ___________________________ _ 

Exchangeable cations in subsurface sediments ______________________________ _ 

Sediments in the Tulare-Wasco area __________________ _ 

Source of sediments ____________________________ _ 

Types of deposits ______________________________ _ 

Marine deposits ___________________________ _ 

Alluvial-fan deposits _______________________ _ 

Lacustrine and flood-plain deposits ___________ _ 

Particle sizes __________________________________ _ 

Particle sizes of nonmarine sediments _________ _ 

Particle sizes of marine sediments ____________ _ 

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Sediments in the Tulare-Wasco area-Continued 

Partic~e size3-Continued 

Spatial distribution of particle sizes __ ---------

Interrelations of particle-size measures ____ ---_-

Alluvial-fan sediments ______ - _____ --.:.----

Shallow-marine sediments ________ --------

Clay minerals and associated ions ___ -- ____ --------

Clay minerals and their assemblages ______ -- _-

Sources of clay minerals ________ - ____ --------

Total clay-mineral content of sediments_---.. -·-

Ions associated with clay minerals ________ ----

Distribution of exchangeable cations_---- -

Sulfate in the marine siltstones ____ ------ -· 

Sediments in the Santa Clara Valley ____ -- ___ -------... 

Source of sediments ____________ -----_---------- -

Types of deposits _________ --------------------.. -

Modern alluvial sediments and soils ___________ _ 

Older alluvial sediments and soils _____________ _ 

Absence of estuarine deposits ___________ - - - -· .. -

Rates of deposition __________ --- __ --------- -

Particle sizes __________ - - - - - - - - - --- - - - - - - - - - - - - -

Spatial distribution of particle sizes _______ --_ 

Interrelations of particle-size measures _____ --_ 

Clay minerals and associated ions __ ---- ___ -------

Clay-mineral assemblage _______________ -----

Total clay-mineral content of sediments ____ -_ 

Exchangeable cations ______ - - - - - - - - - - - - - --- - -

Clay minerals in the Arvin-Maricopa area ____ -_------ . 

Summary of results of petrologic study __ -- __ --------- -

Determination and description of particle sizes ______ -_ -

Sam piing and particle-size analysis __________ - - - - - ·-

Description of particle sizes _________ - ____ -------... 

Skq.pfQDq,, or Bowley's measure of skewness_-_---_-

Tables of particle-size-distribution data and derived 

measures ______________ -_------------------.. -

Analytical procedures and tabulated results of claymineral study ____________ ------------------------· 

Clay-mineral separation ______ -------------------

X-ray diffraction __________ ---------------------

Identification of clay minerals ________________ -- __ 

Montmorillonite and vermiculite ________ ---- __ 

Mixed-layer montmorillonite-illite ________ --- __ Illite _____________________________________ _ 

Low-grade illite-montmorillonite mixture _____ _ 

Chlorite ____________________ --- ____ --------

Kaolinite-type mineraL ______ --- _____ -------

Minor chloritic minerals ______ --- ___ ---------

Relative proportions of mineral species ________ - - __ 

Exchangeable-cation and soluble-anion analyses ___ _ 

Measurement of pH __________ -------------------

Tables of data on clay minerals and chemical 

analyses ____________________________________ _ 

References ________________________________________ _ 

Index ____________________________________________ _ 

III 

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IV CONTENTS 

ILLUSTRATIONS 

Page 

FIGURE 1. Map showing principal areas of land subsidence______________________________________ Cl 

2. Map of Los Banos-Kettleman City area showing location of core holes__________________ 4 

3. Diagrams of principal sources and types of deposits represented by sediments cored in 

the Los Banos-Kettleman City area______________________________________________ 6 

4. Diagrammatic cross sections of clay aggregates showing progressive stages of development 

from undisturbed clay layers ___________________________________ -:________________ 8 

5. Diagrams of sand-silt-clay percentages of sediments from Mendota, Cantua Creek, and 

IIuron cores------------------------------------------------------------------- 10 

6. Graphs showing measures of average size, sorting, and skewness in sediments from 

Mendota, Cantua Creek, and IIuron cores________________________________________ 11 

7. Diagrams showing variations in particle size with depth, Los Banos-Kettleman City area_ 13 

8. Graphs showing relation of median diameter to sorting and skewness in shallow marine 

sediments_____________________________________________________________________ 14 

9. Diagram of CM patterns_________________________________________________________ 15 

10. Diagrammatic particle-size-distribution curves (probability scale) of sediments deposited 

by tractive currents and turbidity currents________________________________________ 15 

11. Diagram showing OM patterns of modern surficial alluvial-fan deposits, Los BanosKettleman City area___________________________________________________________ 16 

12. Graphs of median diameter against coarsest percentile, sorting, and skewness in floodplain and alluvial-fan sediments, Los Banos-Kettleman City area____________________ 16 

13. Diagrams of clay minerals in cored sediments, Los Banos-Kettleman City area__________ 19 

14. Map showing location of sampling sites for clay minerals in Recent surface alluvial sediments, Los Banos-Kettleman City area___________________________________________ 20 

15. Diagrams of cations adsorbed by clay minerals in principal streams and cores, Los BanosKettleman City area___________________________________________________________ 25 

16. Map of Tulare-Wasco area showing locations of core holes____________________________ 26 

17. Diagrams of source and principal types of deposits represented by sediments cored in the 

Tulare-Wascoarea_____________________________________________________________ 27 

18. Photomicrographs of soil textures in alluvial sediment from depth of 232 feet in Richgrove 

core__________________________________________________________________________ 27 

19. Diagrams of sand-silt-clay percentages of sediments cored in the Tulare-Wasco area______ 30 

20. Graphs showing measures of average size, sorting, and skewness in nonmarine sediments 

cored in the Tulare-Wasco area__________________________________________________ 31 

21. Graphs showing measures of average size, sorting, and skewness in marine sediments from 

the Richgrove core_____________________________________________________________ 31 

22. Diagrams showing variations in particle size with depth, Tulare-Wasco area_____________ 32 

23. Graphs of median diameter against coarsest percentile, sorting, and skewness in alluvialfan and shallow-marine sediments, Tulare-Wasco area______________________________ 33 

24. Diagrams of clay minerals in cored sediments, Tulare-Wasco area______________________ 34 

25. Diagrams of cations adsorbed by clay minerals in cored sediments, Tulare-Wasco area____ 35 

26. Graphs showing relation of the proportion of adsorbed sodium to salt concentration and 

pii in sediments below 760 feet in the Richgrove core______________________________ 36 

27. Graphs showing soluble salts, soluble anions, and pH of fine-grained sediments from the 

Richgrove core________________________________________________________________ 37 

28. Map of Santa Clara Valley showing location of core holes_____________________________ 39 

29. Diagram of sand-silt-clay percentages of sediments cored in the Santa Clara Valley_______ 42 

30. Graphs showing measures of average size, sorting, and skewness in sediments cored in the 

Santa Clara ValleY--------------------,---------------------------------------- 42 

31. Diagrams showing variations in particle size with depth, Santa Clara Valley_____________ 43 

32. Graphs of median diameter against coarsest percentile, sorting, and skewness in alluvial 

sediments, Santa Clara Valley___________________________________________________ 43 

33. Diagrams of clay minerals in cored sediments, Santa Clara Valley______________________ 44 

34. Map showing location of core holes and sampling sites for clay minerals in Recent surface 

alluvial and bay-bottom sediments, Santa Clara Valley_____________________________ 45 

35. Diagrams of cations adsorbed by clay minerals in cored sediments, Santa Clara Valley____ 46 

36. Map of Arvin-Maricopa area showing location of Lakeview test hole___________________ 47 

37. Diagram of clay minerals in cored sediments from Lakeview test hole_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 48 

38. Graph showing relation between Skqq,/QD.p and log10 Sk_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 51 

39. X-ray diffraction patterns of oriented aggregates of expanding clay minerals_____________ 67 

40. X-ray diffraction patterns of oriented aggregates of chlorite and kaolinite-type minerals__ 70 
CONTENTS 

TABLES 

Page 

TABLE 1. Core holes and details of coring__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ C3 

2. Criteria for distinguishing alluvial-fan, flood-plain, lacustrine, and deltaic deposits, Los 

Banos-Kettleman City area_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 7 

3. Criteria for distinguishing conditions under which fine-grained sediments were deposited, 

Los Banos-Kettleman City area__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 7 

4. Evidence for conditions of deposition represented by sediments in Richgrove core, TulareVVascoarea___________________________________________________________________ 28 

5. Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los 

Banos-Kettleman City area ____________________________________ ~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 51 

6. Particle-size data for selected fine-grained sediments from cores and streams, Los BanosKettleman City area___________________________________________________________ 58 

7. Particle-size data for selected well-sorted sands from Mendota, Cantua Creek, and Huron 

cores, Los Banos-Kettleman City area____________________________________________ 58 

8. Particle-size data for cored sediments, Tulare-VV asco area___________________________ 60 

9. Particle-size data for cored sediments, Santa Clara Valley____________________________ 63 

10. Proportions of clay minerals in two clay-size fractions of sediments from Los Banos-Kettle- man City area_________________________________________________________________ 66 

11. Clay minerals and associated ions in fine-grained sediments from cores in Los BanosKettleman City area_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 73 

12. Clay minerals and associated ions in surface and near-surface alluvial sediments, Los 

Banos-Kettleman City area_____________________________________________________ 74 

13. Clay minerals and associated ions in fine-grained sediments from cores in Tulare-VV asco area__________________________________________________________________________ 75 

14. Clay minerals and associated ions in fine-grained sediments from cores in Santa Clara 

ValleY------------------------------------------------------------------------ 76 

15. Clay minerals and associated ions in fine-grained surficial sediments from Santa Clara 

Valley and southern San Francisco Bay ________________________________ --________ 77 

16. Partial chemical analyses of water from selected wells within about 3 miles of Sunnyvale core hole ____________________________________________________________________ ·_ 77 

17. Partial chemical analyses of water from wells within 200 yards of San Jose core hole______ 78 

18. Clay minerals in fine-grained sediments from Lakeview test hole, Arvin-Maricopa area___ 78 

MECHANICS OF AQUIFER SYSTEMS 

PETROLOGY OF SEDIMENTS UNDERLYING AREAS OF LAND 

SUBSIDENCE IN CENTRAL CALIFORNIA 

By RoBERT H. MEADE 

ABSTRACT 

A diversity of particle sizes and a uniformity of clay-mineral 

assemblages has been shown by a study of the petrologic characteristics that influence compaction-particle sizes, clay minerals, and associated ions-in fresh-water-bearing sediments 

underlying areas of land subsidence related to ground-water 

withdrawal in centool California. 

The sediments underlying the Los Banos-Kettleman City 

area of the western San Joaquin Valley are alluvial-fan, floodplain, lacustrine, and deltaic deposits; the sources of the sediments were the Sierra Nevuda and Diablo Range. They are 

diverse and heterogeneous in texture, often poorly sorted, and 

their geometric-mean particle size is probably between 30p. and 

60,u. Montmorillonite is the principal clay mineral, accounting 

for 70 percent of the clay-mineral assemblage and 10 percent 

of the sediments as a whole. Calcium is the predominant exchangeable cation. 

The sediments underlying the Tulare-Wasco area of the southeastern San Joaquin Valley are mainly alluvial-fan and shallowmarine deposits, plus subsidiary flood-plain and lacustrine 

deposits; all are derived from the Sierra Nevada. The nonmarine sediments are mostly poorly sorted and heterogeneous, 

having a mean particle size of 40p.-80,u. The shallow-marine 

sediments are more un:iform, consisting of siltstone (mean particle size 5,u-10p.) and fairly well sorted sands (mean particle 

size 250p.-500,u). Montmorillonite (plus some vermiculite) is 

the principal clay mineral, comprising about 10 percent of the 

nonmarine sediments and 20 percent of the marine siltstones. 

Calcium is the dominant exchangeable cation in the nonmarine 

sediments. The exchangeable-cation assemblage in the marine 

siltstones is more diverse, consisting of variable proportions of 

calcium, sodium, magnesium, and hydrogen. 

The uppermost 1,000 feet of sediments underlying the Santa 

Clara Valley is alluvial, with perhaps a few minor interbedded 

lacustrine deposits ; the sources of the sediments were the 

adjoining Santa Cruz and Diablo Ranges. Coarser sands and 

gravels (mean size on the order of 500,u-1,000,a) are found 

below the courses of the main streams of the v,alley. Finer silts 

and clays (mean size on the order of 5,u-10p.) underlie the 

parts of the valley away from the main streams. Montmorillonite is again the dominant clay mineral, comprising between 

5 and 25 percent of the sediments, depending on the general 

fineness of their particle size. Calcium is ;the dominant exchangeable cation. 

In the sediments underlying the Arvin-Maricopa area at the 

southern end of the San Joaquin Valley, the clay-mineral assemblage is also dominated by montmorillonite. 

INTRODUCTION 

The petrologic characteristics of sediments determine 

their responses to changes in overburden load. Detailed know ledge of these characteristics-especitJ,lly 

particle size, clay-mineral and exchangeaJble-cation 

composition and the constituents dissolved in inter- ' . stitial waters-and how they vary in any group of sediments is therefore necessary for a fuller understanding 

of the compaction of the sediments. 

The sediments whose compaction accounts for the 

subsidence of the land surface in four areas of the San 

Joaquin and Santa Clara Valleys of California (fig:. 1) 

are the subject of this report. The compaction and 

'"tl 

';» 

124,.--~ 123' 122' 121' 120' 

n 39' -r-t-----t"~-'-+'l<>t-->~,..,:r""l.--t20 0 20 

117' 116' 

100 MILES 

FIGURE 1.-Principal areas of land subsidence in central CaUEornia. 

Heavy lines enclose areas of larger scale maps in figures 2, 16, 28, 

and 36. 

Cl 
02 MECHANICS OF AQUIFER SYSTEMS 

land subsidence in these areas are clearly related to the 

depletion of artesian pressure (increase of grain-tograin load) in the sediments, which is a result of confined ground water being pumped from the sediments 

faster than it is being replenished. Because the rates 

of compaction and subsidence are rapid and can be 

measured, these areas were selected as field laboratories 

for a program of study of the mechanics of aquifer 

systems. Because the compaction represents an acceleration of the natural processes that would have taken 

place with the further accumulation of overlying sediments, these are also opportune areas for general studies 

of the compaction of sediments. A fuller discussion of 

the problems of land subsidence and aquifer compaction 

and the ways in which the problems have been approached in this program are given by J. F. Poland in 

his foreword to the first chapter of this series (Johnson 

and others, 1967) . 

PURPOSES OF REPORT 

This report is one of a series, all chapters of Professional Paper 497, on the mechanics of aquifer systems in California and elsewhere. It is also the second 

of three chapters by the same author that treat the 

petrologic aspects of compaction. The first of these 

three chapters, B (Meade, 1964), is a comprehensive 

review of previous work on the factors that influence 

pore volume and fabric of clayey sediments under increasing overburden loada. The second of the 

chapters-this report-is mainly descriptive and is intended to serve a dual purpose. Its first concern is the 

variation and distribution of some of the petrologic 

factors that the review of previous work shows to 

be significant influences on compaction. It is also 

meant to be a contribution to the general petrology 

of the post-Miocene fresh-water-bearing sediments of 

the San Joaquin and Santa Clara Valleys of California. 

The results are presented in a form that can be compared readily with the results of similar analyses of 

sediments in other areas-whether the comparison be 

for petrologic or engineering purposes. The third 

chapter (R. H. Meade, Compaction of sediments underlying areas of land subsidence in central California, 

in preparation as Prof. Paper 497-D) relates, by 

statistical analysis, the variations in overburden load 

and petrologic factors to variations in the pore volume 

and fabric of the sediments. Although it may inconvenience the reader, the division of the petrologic study 

into three chapters limits the bulk and, hopefully, enhances the readability of the separate reports. 

Descriptions of the sources and inferred modes of 

deposition begin the discussions in this report of the 

sediments of each of the areas. These descriptions are 

1nainly meant to provide a general background and a 

spatial framework for the discussions of specific petrologic characteristics that follow them. 

The sections of this report that deal with particle size 

are an extension of the presentation and discussion of 

particle-size data given by Johnson, . Moston, and 

Morris 1967). Although the two discussions are 

based on the same sets of size analyses, they overlap 

only slightly. Whereas Johnson and his associates 

presented the results of the analyses with no interpretation, the discussions in my report are aimed toward (1) 

describing the variations in particle size and arriving 

at meaningful estimates of average size, (2) describing 

the spatial variations in particle size, ( 3) describing the 

relations of particle size to source areas and types of 

deposits, and ( 4) finding consistent relations between 

the particle-size measures themselves. These efforts 

involve a moderate use of statistical techniques. 

The sections of the report that concern the clay 

minerals and associated ions are aimed toward ( 1) 

estimating the total amount of clay-mineral material 

as well as the relative amounts of the different claymineral species in the sediments, (2) describing the 

exchangeable oaJtions and soluble salts associated with 

the clay minerals, and (3) making some tentative 

judgments of the origins of the different clay minerals. 

COLLECTION OF &LES 

The samples on which this study is based came mostly 

from eight core holes, four in the Los Banos-Kettleman 

City area and two each in the Tulare-Wasco area and 

Santa Clara Valley, and from one test hole in the ArvinMaricopa area. All the coring was done by drilling 

crews of the U.S. Bureau of Reclamation. Details of 

the coring are given in table 1. Locations of the holes 

are shown in figures 2, 16, 28, and 36. The sediments 

were sampled with a rotary-driven core barrel 3 inches 

in diameter. Cores were logged by visual examination 

at the drilling sites, and selected samples were sealed 

in wax for later study. Samples from seven of the 

holes-all but the Oro Lorna core in the Los BanosKettleman City area and the few sediments that were 

cored in the Lakeview test hole in the Arvin-Maricopa 

area-were analyzed for physical and hydrologic properties by the Hydrologic Laboratory of the U.S. Geological Survey in Denver. Samples from all the holes 

were studied petrographically. 

In addition to the core-hole samples, surficial samples 

from the Los Banos-Kettleman City area and the Santa 

Clara Valley were included in the study of clay minerals. These samples were collected by W. B. Bull, T. J. 

Conomos, and me. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA 03 

TABLE 1.-Core holes and details of coring . 

Location of core hole Depth of 

(township/ core hole Cored intervals 

Nearest town range-section: (feet be- (feet below land surface) Mount Diablo low land 

base line and surface) 

meridian) 

Los Banos-Kettleman City area 

Oro Lorna _______ 12S/12E -16 1,005 30-40, 70-85, 110-120, 150-

160, 180-190, 230-240, 

270-281, 320-329, 360-

Core re- co very (percent 

total 

cored 

intervals) 

73 

cisco Bay. Claude Huffman, A. J. Bartel, H. H. Lipp, 

and I. C. Frost determined the soluble anions associated 

with the clays. H. C. Starkey and T. Manzanares determined the exchangeable cations. K. E. Lohman, 

Ellen J. Moore, Patsy B. Smith, and D. W .. Taylor 

identified some of the fossil remains. Meyer Rubin 

provided a radiocarbon date. 

I. E. Klein, of the U.S. Bureau of Reclamation, l~~nt 

me a large collection of core-hole samples that were 

Mendota _________ 14S/13E -11 1,.'i00 

Cantua Creek ____ 16S/15E -34 2, 000 I (2, 007) 

1,005. 

30-40, 70-80. 110-120, 150-

160, 190-200, 230-240, 

270-280, 310-320, 350-

360, 390-400, 430-440, 

470-480, .'i10-520, 550-

560, 590-600, 630-1,497. 

250-260, 290-300, 330-340, 

370-380, 410-420, 450-

460, 490-1,050, 1,150-

1,600, 1,630-1,640, 1,670-

7 

5 

o taken for his use, and he determined the source areas 

of the sediments in the Oro Lorna core. The San Jose 

Water Works and the California Department of Water 

Resources provided chemical analyses of ground water 

in the Santa Clara Valley. 

1,680, 1,710-1,720, 

1,750-1,760, 1,790-1,800, 

1,830-1,840, 1,870-1,880, 

1,910-1,920, 1,950-1,960, 

In the determination of clay minerals, I was assisted 

in the laboratory by J. 0. Berkland, W. R. Cotton, F. 

1,990-2,000. Huron 5 ___________ 19S/17E -22 2,203 30-40, 80-90, 120-130, 160-

170, 210-220, 230-240, 8 P. N angler, and, most extensively and ably, by J. B. 

Pixley ___________ 23S/25E -16 

Richgrove _______ 24S/26E -36 

Sunnyvale _____ __! 6S/ 2W-24 

San Jose_________ 7S/1E -16 

Lakeview ________ 11N/21W-3 2 

270-280, 310-320, 350-

360, 390-400, 4-30-440, 

470-480, 510-520, 550-

560, 590-600, 630-640, 

670-680, 710-2,110. 

Tulare-Wasco area 

760 30-40, 70-80, 110-120, 150-

160, 190-200, 230-240, 

260-752 

2,200 50-1,900, 1,908-1,965, 

2,000-2,012, 2,040-2,061, 

2,090-2,110, 2,140-2,180. 

Santa Clara Valley 

1, 00! 30-265, 300-365, 400-467, 

512-581, 600-675, 710-995. 

1, 002 30-40, 70-80, 1C7-140, 150-

165, 185-290, 300-356, 

401-455, 500-618, 694-850, 

900-956. 

Arvin-Maricopa area 

1, 500 335-339, 392-404, 530-543, 

660-666, 685-696, 830-

836, 1,146-1,155, 1,455-

1,460. 

73 

81 

69 

30 

57 

I Depth from electric log. After electric log was run, the drill pipe (newly acquired) was measured and found to be 0.35 rt longer per 100ft than figured during coring. 2 San Bernardino base line and meridian. 

ACKNOWLEDGMENTS 

This report describes the results of a large number 

of laboratory analyses and programs, many of which 

were carried out by members of the U.S. Geological 

Survey other than me. The Hydrologic Laboratory of 

the Survey in Denver ma:de the particle-size analyses. David Handwerker wrote a machine program to 

compute statistics from the particle-size analyses. J. C. 

Hathaway, H. C. Starkey, and G. W. Chloe determined 

the clay minerals in a group of 25 samples from the 

Los Banos-Kettleman City area. T. J. Conomos determined the clay minerals in sediments from San FranCorliss. L. K. Lustig reviewed sections of the manuscript. The counsel and guidance of J. F. Poland and 

Julius Schlocker, as well as the observations, findings, 

discussions, and criticisms of my colleagues on the project-W. B. Bull, J. H. Green, A. I. Johnson, B. E. 

Lofgren, R. E. Miller, and R. P. Moston-contributed 

heavily to the substance and form of the report. 

SEDIMENTS IN THE LOS BANOS-KETrLEMAN CITY. 

AREA 

In the Los Banos-Kettleman City area, the sediments 

whose compaction accounts for the observed land subsidence are almost entirely nonmarine-mostly alluvial. 

They came from the Diablo Range that forms the southwestern border of the area and from the Sierra N eva~da 

that lies across the San Joaquin Valley to the northeast. The sediments occur chiefly within the Tulare 

Formation or the alluvium that lies above the Tula,re. 

Locally, however, in the southern part of the area, 

deep water wells tap sediments within the Etchegoin 

and San Joaquin Formations. The age of these sediments is not closely defined; but the lowermost are no 

older than middle Pliocene, and the uppermost were 

deposited in modern times. 

This study is based on samples taken from four core 

holes that were drilled into these sediments, about to 

the base of the Tulare Formation. Locations of the 

core holes, all of which are in western Fresno County, 

are shown in figure 2. 

The geology of the sediments that are undergoing 

artificially induced compaction is described in detail by 

Miller, Green, and Davis, in preparation as Professional Paper 437-E. Other reports by Bull (1964a, h), 
C4 MECHANICS OF AQUIFER SYSTEMS 

Los Banos 

• 

MENDOTA Mendota • (14/13-11 D1) 

/ 

"'1 

~ 

< .._/""• 0 

~~:· 

'?.~~~ 

.. r 

EXPLANATION 

/ /T//T/T//7 

Boundary of deformed rocks 

G"···~ 

7 

\ 

Kerman 

• 

Five Points 

• 

HURON 

(19/17-22J1, 2) 

0 0 

Core-hole location Westhaven 

•Huron 

/ 

5 0 5 10 MILES / 

FIGURE 2.-Los Banos-Kettleman City area showing location of core holes. 

\ ... 

'\._ .. ..---lc_---

I ···---?--···""-··· I ( r-' ... / .· 

ojlo 

uu ~ 

Oloo { 

~~~ ~~~ ( ~, \. / Stratford f 

Tulare 

Lake 

Bed 

Kettleman 

• City 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C5 

describe the lithology and depositional history of the 

alluvial deposits of Quaternary age in the Los 'BanosKettlemnn City area. 

SOURCES OF SEDIMENTS 

The Tulare Formation and younger alluvium represented by the cores in the Los Banos-l{ettleman City 

area were derived from two mountainous terranes: the 

Diablo Range on the west side of the San Joaquin 

Valley and the Sierra Nevada on the east side (fig. 2). 

The streams that flow from the Diablo Range into this 

part of the valley drain mostly areas of folded, but 

otherwise unmetamorphosed, Cretaceous and Cenozoic 

sedimentary rocks; some streams also drain areas underlain by the partly metamorphosed sediments and 

ultramafic rocks of the middle-to-late Mesozoir Franciscan Formation. In the central Sierra Nevada, the 

rocks underlying the principal drainage basins are 

markedly different from the rocks in the Diablo Range. 

Sierra Nevada rocks are mainly granitic but include 

lesser amounts of metamorphic rocks and Cenozoic sediments. Deposits derived from the two sides of the 

valley, therefore, are easily distinguished from each 

other on the basis of their minerals and lithic fragments. 

SOURCE CRITERIA 

The sources of the Tulare Formation and younger 

sediments in the four cores were determined by exam ining silts, sands, and what gravels were available under 

the binocular microscope. This examination was supplemented by petrographic-microscope examination of 

a few thin sections of well-sorted sands. The clays 

were assumed to have come from the sa.me sources as 

intercalated silts, sands, and gravels. 

The typical sands from the Sierra Nevada are lightcolored and micaceous and contain more than 25 percent feldspar-enough for them to be called "arkosic" 

by Gilbert's definition (Williams and others, 1955, p. 

292-295). The amount of mica ranges from 2 to 5 

percent and is nearly all biotite in fresh-looking flakes 

or books. The biotite grains are usually the same size 

as the principal nonmica grains or larger. The sands 

also contain 1-2 percent of green hornblende in prismatic grains. 

Sands from the Diablo Range are darker-some consisting of more than 30 percent dark grains-and generally contain more lithic fragments. The characteristic dark constituents are sub rounded rock fragments: 

partly altered andesite, greenish serpentinite in rounded 

and often oblate grains, and brick-red chert in subangular to sub rounded grains. Mica is present in amounts 

of 2 percent or less, usually in weathered-looking flakes 

that are the same size as the principal nonmica grains 

or smaller. 

The principal sources of the core-hole sediments~ as 

determined by the above criteria, are shown in figure 3. 

Small admixtures-for example, a few grains of chert 

and serpentine mixed with sediments mainly from the 

Sierra Nevada-are not shown. Such mixtures are typical of flood-plain ·and lacustrine deposits. The sources 

of the sediments below 1,600 feet in the Cantua Creek 

core could not be determined with certainty because only 

25 percent of this interval of sediment was cored and 

only 15 percent of the interval was recovered. 

ANDESITIC SANDS 

Andesitic detritus is a common constituent of the 

sands from the Diablo Range. It is especially abund:ant 

in the sands that lie between 1,500 and 1,000 feet below 

the surface in the Mendota core and between 1,000 and 

500 feet in the Oro Lorna core. It is probably derived 

from older Pliocene ·andesitic sandstones of the Etehegoin and San Joaquin Formations that crop out on the 

east flank of the Range. 

These Pliocene sandstones have been described by 

Lerbekmo ( 1957, 1961). They consist largely-in some 

places almost entirely-of fresh andesitic debris: intermediate plagioclase, 40-70 percent andesitic rock fragments, and 10-30 percent ferromagnesian minerals .. A 

characteristic feature is their striking blue color, which 

is caused by grain coatings of authigenic montmorillonite derived from the solution of volcanic detritus 

within the sandstones. 

The andesitic sands in the Tulare Formation and 

younger sediments as examined in the cores differ 

significantly from the Pliocene sandstones, and the differences indicate that the sands probably came in part 

from older rocks. Andesitic detritus in the younger 

sands is always mixed with other Diablo Range material-most conspicuously chert and serpentine--and 

andesite rock fragments generally comprise less than 25 

percent. These andesite fragments are generally somewhat altered. Within the Mendota core, the alteration 

seems to increase with a decrease in the age of the sediments, suggesting that perhaps the andesitic material 

was reworked more than once. The grain coatings are 

only sporadically developed and are not so intensely 

blue as those in the sandstones of the Pliocene Etchegoin and San Joaquin Formations exposed on Anticline 

Ridge. 

TYPES OF DEPOSITS 

Three main types of deposits, all waterlaid, have been 

recognized in the Tulare Formation and younger sediments of the area: these are alluvial-f-an, flood-plain, 

and lacustrine deposits. As figure 3 suggests, the two 
C6 MECHANICS OF AQUIFER SYSTEMS 

-

-

-

ORO LOMA 

CORE 

SOURCE TYPE OF 

DEPOSIT 

DR AF 

........-SN 

FP 

0 

- -

-

- 1-

MENDOTA 

CORE 

SOURCE TYPE OF 

DEPOSIT 

AF 

DR 

DR+SN "'-DR LA r--

- - 500 i-

- - 1- FP 

- DR FP - DR+SN LA 

- - r-- SN 

- - SN+DR FP 

1000 r--

1-

r-- DR 

1- AF 

f- LA(?) 

EXPLANATION 

SOURCE TYPE OF 

DEPOSIT 

DR, Diablo Range AF, Alluvial fan 

SN, Sierra Nevada FP, Flood plain 

LA, Lacustrine 

0 

-

-

-

-

500 

-

-

-

- 1000 

-

-

-

-

1500 

CANTUA CREEK 

CORE 

SOURCE TYPE OF 

DEPOSIT 

1- -

1- DR AF -

r-- -

r-- -

r- -

- DR+SN LA -

- - DR AF -

-

- -

1- -

1- FP -

1- - SN 

_..--LA(?)-

r--

f- - FP 

------- - Mostly DR(?) ------- -------

-Mostly SN(?) LA(?) -

0 

500 

1000 

1500 

2000 

t-

~ 

r-

-

-

-

1-

1-

fi1-

-

i-

-

-

f1-

HURON 

CORE 

SOURCE TYPE OF 

DEPOSIT 

DR AF 

DR+SN LA 

DR AF 

SN+DR 

Deltaic 

SN 

0 

-

-

- UJ 

(.) 

- 500 <( 

LL. 

0::: - :::J 

en -

Cl - z 

<( - -' 

- 1000 ~ 

0 - -' 

UJ 

- m 

1-

UJ 

UJ - LL. 

- 1500 z 

- :i 

1- - ll. 

UJ 

Cl 

-

- 2000 

2200 

FIGURE 3.-Principal sources and types of depo,sits represented by sediments cored in the Los Banos-Kettleman City a:rea. Sources of 

Oro Loma core identified by I. E. Klein. Types of deposits identified mainly by R. E. Miller. 

alluvial types are far more abundant than lacustrine deposits. A subsidiary type, the deltaic deposits, was 

identified near the bottom of the Huron core. 

These deposits were recognized and delineated mainly 

by R. E. Miller, from whom much of this section of the 

report has been taken. Only selective descriptions of 

the deposits and their modes of deposition are given 

here; they are intended to emphasize the conditions ·thwt 

influenced the response of the sediments to compaction. 

Fuller description of the deposits and their spatial distributions are given in the report by Miller, Green, and 

Davis, in preparation as Professional Paper 437-E. 

CRITERIA FOR DISTINGUISHING PRINCIPAL TYPES OF 

DEPOSITS 

LARGE-SCALE CRITERIA 

Table 2 gives the large-scale criteria, developed 

mainly by R. E. Miller, that were used to distinguish the 

types of deposits. These criteria reflect the different 

sets of conditions-mainly hydraulic and chemicalthat constitute the different depositional "environments." They are listed in decreasing order of the use 

that was made of them in separating the different depositional types. See the geologic cross sections and 

isopach mRps of Miller, in preparation as Professional 

Paper 437E, for evidence on the distribution and shwpe 

of the several types of deposits. 

Alluvial-fan deposits were the easiest to distinguish 

from the other types, primarily on the basis of the color 

of the sediments, substantiated by their wedge shape in 

three dimensions. The characteristic yellow brown is a 

result of the long period of oxidation between deposition and burial below the water table. The "oxidized" 

color is retained even after burial to 1,500 feet or more 

below the water table. . 

The distinction between flood-plain and lacustrine 

deposits is less certain, for it has to be made on the basis 

of organic remains and the nature and distribution of 

the sediments within the deposit. The distinction between the two types becomes tenuous in the case of nonfossiliferous and generally fine-grained sediments that 

were deposited in large depressions or abandoned channels on a flood plain. Such sediments were called floodplain deposits unless correlation of electric logs showed 

them to be extensive, continuous, and consistently fine 

grained. 

TEXTURAL EVIDENCE OF PROCESSE.S OF DEPOSITION IN 

FINE-GRAINED SEDIMENTS 

Further evidence of the depositional history of the 

fine-grained sediments-clays and clayey silts-came 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C7 

TABLE 2.-Criteria for distinguishing alluvial-fan, flood-plain, lacustrine, and deltaic deposits, Los Banos-Kettleman City area 

[Color code from Rock-Color Chart (Goddard and others, 194Sl)) 

Criterion Alluvial-fan deposits 

Color of sediment_ ________________ Yellowish brown (lOYR); lesser 

Nature and distribution of sedi- ment within the large-scale deposit. 

Source of constitutent grains _____ _ 

Three-dimensional shape of 

deposit in large scale (horizontal dimensions in miles or tens of miles). 

amounts of grayish brown 

(5YR) and olive brown (5Y). 

Color due to staining of 

grains by iron oxide. 

Heterogeneous and variable; 

lenses, tongues, and beds of 

clay, silt, sand, and gravel grade into one another or change abruptly both vertically and laterally. Sands 

may be crossbedded. 

From one side of the San 

Joaquin Valley only. 

Wedge shaped, with thickest 

part toward mO''ntains from 

which materials came. 

Organic materiaL ________________ Plant material in small fragments diss3minated through sediment; in trace amounts or a few percent at most. 

Flood-plain deposits 

Greenish grays and grayish 

greens (5G, 5GY, lOG), dark 

gray (N), bluish gray (5B), 

blue green 15BG). Authigenic iron sulfides often 

present. 

Same as alluvial-fan deposits. 

From both sides of the San 

Joaquin Valley. 

Lenticular. 

Plant material in fragments both large and small: larger pieces often intact enough for structures to be discerned. 

Lacustrine deposits 

Same as flood-plain depo'lits. 

Uniform; may be homogeneous for thicknesses of tens of feet. Generally fine 

grained. 

From both sides of the San 

Joaquin Valley. 

Layered or lenticular, but 

widespread and fairly uniform in thickness. 

Plant material in fragments, often large and structurally intact. Also fresh-water 

organisms such as diatoms 

and mollusks. 

Deltaic deposits 

Same as flood-plain deposits. 

Heterogeneous but gem•rally coarse grained. Sands com- monly crossbedded. 

From both sides of the San 

Joa';luin Valley but chiefl~ 

from Sierra Nevada. 

Lenticular. 

Plant material in fragments, often large and structurally intact, in peatlike accumu- lations. High proportion of 

finely disseminated orgamc material in some clays. Fragments of fresh- and 

brackish-water mollusks; fish 

remains. 

from observations or measurements made on short core 

samples, 2-5 em thick. Diagnostic textural features 

are listed in table 3 in decreasing order of their usefulness. In small samples one cannot make the threeway distinction illustrated in table 2, but must confine 

oneself to two categories: sediments deposited by moving streams and those deposited in standing water. 

Because of the lack of definitive criteria in small 

samples, neither distinction could be made in hand 

specimens of coarser grained sediments. 

The most distinctive textural feature of the finegrained sediments deposited by moving streams in the 

Los Banos-Kettleman City area is a chaotic fabric. In 

some hand specimens the clay-size particles seem to 

be concentrated in sand-sized aggregates which are 

usually rounded to subrounded and are platy, oblate, 

or spherical in shape. The aggregates, when present, 

are in a matrix of sand-silt-clay, in concentrations 

ranging from a few percent to nearly half the sedin1ent. 

In thin sections the aggregates appear to consist mainly 

of well oriented clay-mineral particles. The orientation of the aggregates with regard to each other, however, is generally random. 

TABLE 3.-Criteria for distinguishing conditions under which fine-grained sediments were deposited, Los Banos-Kettleman City area 

Criterion 

Fabric: 

Discernible in hand specimen ____ _ 

Discernible in thin section ______ _ 

Deposited by moving water 

Often chaotic: Clays in chunks or rounded 

sand-sized aggregates in matrix of poorly 

sorted sand-silt-clay. 

May be bedded: Marked differences in 

particle size between adjoining laminae. 

Clay laminae may have graded contact 

with underlying laminae and abrupt 

contact with overlying laminae. 

Chaotic: Small aggregates' of well-oriented 

clay in random orientation with regard to 

other aggregates. A little mass extinction in matrix. 

Clay-particle 1.5 or less _____________________________ _ orientation ratios 

measured by X-ray method. 1 

Porosity___________________________ Relatively less 2 ________________________ _ 

Organic materiaL___________________ Plant material in traces, or a few percent at 

most, disseminated in small fragments. 

Coarsest particle in sediment as measured by C, the 1st percentile 

of the size distribution. 

Generally larger than lOO.u-- _____________ _ 

Deposited in standing water 

1------------------

Uniform or distinctly and finely laminated; 

only small differences in particl,e size 

between adjoining laminae. 

Regular preferred orientation of platy 

particles parallel to bedding. Mass extinction well developed over large areru= .. 

1. 5 or more. 

Relatively greater. 2 

As much as 10 percent. Original vegetal 

structures may be intact. Often asso- ciated with authigenic sulfide minerals. 

Generally smaller than 250.u. 

1 Method explained in earlier paper (Meade, 1961). Orientation ratios near 1.0 

denote random orientation; ratios larger thanl.O signify preferred orientation of clay particles parallel to bedding. 

2 No numbers assigned: porosity variable with depth and particle size. 
C8 MECHANICS OF AQUIFER SYSTEMS 

The aggregates probably originated in two ways: 

as fragments of shale that 'vere carried out of the 

mountains and rounded en route and from disruption 

of previously deposited thin layers of clay. Evidence 

of the latter process is found preserved in all degrees 

of disruption, from the undisturbed clay layers to the 

chaotic array of clay aggregates (fig. 4). Apparently, 

after a clay layer has dried to the point where it cracks 

into pieces, the pieces may be picked up and incorporated into the sediment load of subsequent water flows. 

The pieces are then broken, rounded, and deposited in 

a random array together with the other constituents 

of the sediment load. 

0 I CENTIMETER 

Clay Sand, silt, and clay 

FIGURE 4.-Cross sections of clay aggregates showing progressive 

stages of development from undisturbed clay layers. 

In .contrast, the fabric of clays and silts that seem to 

have been deposited in standing water is often uniform. 

Clay particles are oriented parallel to the bedding or 

nearly so. Standing-water deposits are often finely 

bedded, are more consistently fine grained, and are often better sorted. 

The porosity of standing-water sediments seems to 

be greater than that of moving-stream sediments of the 

same particle size. This impression is supported by 

the observations summarized by Gaither (1953, p. 184), 

to the effect that sands deposited in standing water 

generally have greater porosities than those deposited 

subaerially. Perhaps this difference also exists in silts 

and clays. Other factors, however, may be at least 

partly responsible for the greater porosities of the standing-water sediments. The lacustrine Corcoran Clay 

Member of the Tulare Formation contains diatom 

skeletons whose openwork structure seems to contribute 

to the porosity of the enclosing sediments. Another 

coincidental factor is the greater proportion of sodium 

adsorbed by the clays in the lower parts of the cored 

intervals (fig. 15), included in which are most of the 

standing-water sediments other than the Corcoran Clay 

Member. A greater proportion of adsorbed sodium, 

relative to other cations, may contribute to the greater 

porosity of these clays (Meade, 1964, fig. 11). Higher 

porosity, therefore, is not a definitive .criterion in these 

cores for distinguishing the two types of deposits. 

No single criterion given in table 3 is enough to 

identify the conditions of deposition : the proper combination of fabric and porosity is fairly convincing, 

but three criteria are generally necessary for unequivocal identification. Most of the fine-grained alluvialfan deposits in the Los Banos-Kettleman City area fall 

unequivocally into the moving-stream category, although a few oxidized sediments within large wedges of 

alluvial-fan deposits fell into the standing-water 

category. Lacustrine deposits should fall certainly 

into the standing-water category. Silts and clays deposited on flood plains can fall into either category. In 

small segments of cores, one cannot tell whether a nonfossiliferous highly porous greenish- to bluish-gray uniformly and finely bedded clay is a lacustrine or floodplain sediment-this must be determined on the basis of 

the large-scale geometry of the deposit. 

ALLUVIAL-FAN DEPOSITS 

The alluvial fans that occupied this part of the San 

Joaquin Valley in the past are thought of as similar 

to the fans that line the west side of the valley today 

(described in detail by Bull, 1964a, b). The alluvia]. 

fan deposits found in the core holes have been derived, 

as are the modern fan deposits in the area, entirely from 

the Diablo Range. They were deposited by waterflows-streams and sheet flows; very few, if any, mudflows seem to have moved as far out into the valley as 

the locations of the core holes. 

The sediments are unsaturated for substantial depths 

below the surfaces of the modern fans. Throughout 

most of the area, the water table lies more than a hundred feet below the land surface and as much as several 

hundred feet below the surface along the mountain 

front. The principal streams flow only during the 

rainy winter months and are usually dry for more than 

half the year. After leaving the mountain front and 

flowing into the main San Joaquin Valley, they are 

never in complete hydraulic continuity with the water 

table (Rantz and Richardson, 1961; Richardson and 

Rantz, 1961, p. 19, 24, 26, 29). Water from the principal streams percolates into the underlying sediments 

and moves to the water table mainly by unsaturated 

flow. The smaller streams are ephemeral ; that is, they 

flow only fot short periods after rainstorms and are 

never in hydraulic continuity with the water table. 

They' supply very little influ~nt seepage to the groundwater body. Most of the sediments, consequently, remain unsaturated and subject to oxidation between the 

time they are deposited and the time they are buried 

below the water table. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C9 ...... 

FLOOD-PLAIN DEPOSITS 

The flood plains that occupied this part of the San 

Joaquin Valley in the past are thought of as those of 

perennial streams. Sands and gravels were deposited 

in or near the principal stream channels; silts and clays 

were deposited on the adjoining plains when the streams 

overflowed their banks. The water table beneath the 

flood plains was probably close to the land surface : the 

state of preservation of some of the plant remains and 

the presence of authigenic sulfides suggest that the 

flood-plain sediments were not subjected to continued 

aeration and oxidation. 

At different times each side of the valley was the 

principal contributor of the flood-plain sediments found 

in the core holes. 

LACUSTRINE DEPOSITS 

Lakes occasionally covered large portions of this part 

of the valley in late Pliocene and Pleistocene time. 

Sediment was carried into the lakes by streams coming 

from both the Diablo Range and the Sierra Nevada, 

was moved about by currents within the lakes, and was 

deposited by slow settling in relatively still water. 

The most conspicuous of the lacustrine deposits is the 

Corcoran Clay Member of the Tulare Formation which 

lies at depths ranging from 200 to 900 feet below the 

present land surface in nearly half the San Joaquin 

Valley. It has been described and discussed by Frink 

and Kues (1954), and Davis and others (1959, p. 76-81). 

Potassium-argon dating has shown that volcanic ash 

immediately overlying the Corcoran is about middle 

Pleistocene in age (Janda, R. J., in Bull, 1964b, p. A5). 

It is fine grained and ranges in thickness from 0 to 120 

feet. Diatom remains are abundant-as much as 75 

percent of some sediments-in its middle and lower 

parts. Substantial thicknesses of the Corcoran Clay 

Member, 85 and 75 feet, respectively, were cored in the 

Oro Lorna and Mendota holes. 

Other sediments designated lacustrine, in the lower 

parts of the Mendota and Cantua Creek cores, are indicated in figure 3 as of questionable lacustrine origin. 

R. E. Miller identified these deposits 'aS lacustrine ( ~) on 

the basis of their color, fine-grained texture, large-scale 

extent, and dimensions. However, the petrographic 

characteristics of the cored samples of these depositsespecially the degree of regularity of their fabric-do 

not show clear evidence of their having been formed 

in lakes. 

DELTAIC DEPOSITS 

The lowern1ost 400 feet of sediment penetrated by the 

Huron core hole is interpreted by R. E. Miller as a 

deltaic deposit, on the basis of correlation with typical 

delta deposits to the east. These sediments are similar 

to the flood-plain deposits, except that they contain generally more organic remains. Reed, grass, and wood 

remains constitute 15-20 percent of some of the finegrained sediments. Other sediments, in which plant ·remains are not so apparent are colored dark gray (N2--

N3, Goddard and others, 1948) by finely divided 

organic material. Also found in these deposits (at 2,054 

ft) were fragments of the brackish-water gastropod 

assemblage: Littorina, Amnicola, and Fluminicola. 

PARTICLE SIZES 

The study of particle size in the Los Banos-Kettleman 

City area is based on 305 samples from 3 core holes: 

Mendota, Cantua Creek, and Huron (locations shown in 

fig. 2). No particle-size analyses were available for 

samples from the Oro Lorna core. The mean grain size 

in the 305 samples probably lies in the range of fine to 

medium silt, or between10p. and 2011 (microns). Allowing for the fact that the coarsest sediments were not 

sampled adequately (see the discussion of "Sampling 

and particle-size analysis" p. C48), I estimate t:h.at 

the mean particle size of the sediments in the cored 

interval is in the coarse-silt range, or between 30p. and 

6011 • This estimate is based on a comparison of the electrical-resistivity logs of the core holes and the particlesize data on the recovered material. 

Details of the 305 size analyses are given in table 5. 

Percentiles were read from cumulative curves provided 

by the Hydrologic Laboratory. Measures of sorting 

and skewness, computed from the percentiles, are defined on pages C49~C50. 

pARTICLE-SIZE DISTRIBUTIONS OF RECOVERED 

SEDIMENTS 

The particle-size distributions of the cored sediments 

will be illustrated in two main ways: on triangular plots 

of the proportions of sand, silt, and clay; and as 

grouped information about the average sizes, sorting, 

and skewness of the samples. 

The triangular diagram is one of many ways in which 

size data may be summarized, and it is well suited to 

give an overall impression of the range and distribution 

of particle sizes. The reference diagram in figure 5A 

shows the nomenclatural system of Shepard (19!>4). 

The samples are segregated by depositional type in figures 5B-5E; source areas are indicated by open circles 

(Sierra Nevada), dark circles (Diablo Range), and 

crosses (mixed Sierra and Diablo Range). Triangular 

diagrams of the sediments grouped by core holes are 

given by Johnson, 1\{oston, and Morris (1967). 

Looking at figures 5B-5E as a whole, one can see the 

variety and heterogeneity of the particle sizes. There 

is little or no concentration of samples in any category. 
ClO 

SAND AND 

GRAVEL 

SAND 

25 

25 

25 

50 

PERCENT Sl LT 

A 

CLAY 

50 

B 

CLAY 

50 

D 

MECHANICS OF AQUIFER SYSTEMS 

75 

75 SILT 

75 SILT 

EXPLANATION 

MICRONS 

Gravel 

Sand 

Silt 

Clay 

>2000 

62-2000 

4-62 

<4 

SOURCE 

•, Diablo Range 

o, Sierra Nevada 

+. Mixed 

CLAY 

SAND AND 

GRAVEL 

25 50 

c 

CLAY 

SAND 25 50 

E 

75 SILT 

75 SILT 

FIGURE 5.---JSand-silt-clay percentages of sediments fro'm Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman 

City area. Based on data from the Hydrologic Laboratory of the Geological Survey. A, Nomenclature after Shepard 

(1954). B, Flood-plain sediments. 0, Alluvial-fan sediments. D, Lacustrine--including lacustrine( ?)-sediments. 

E, Deltaic sediments (from Huron core only). 
•;11 PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA ~ ...... 

Even though nearly two-thirds of the samples fall into 

the silty clay, clayey silt, and sand-silt-clay fields, and 

more samples fall into the clayey-silt field than into any 

other, the coarser sediment categories in the diagram are 

also well represented. All but 11 of the samples contain 

5 percent or more clay. The amount of gravel included 

in "sand and gravel" in figure 5 (Band 0) is not large. 

Only 24 samples contained gravel (particles larger than 

2,000,u in diameter), and of these, only 12 contained 1 

percent or more. Only four, all flood-plain sediments 

from the Mendota core, had as much as 5 percent gravel. 

The particle-size characteristics of the several types 

of deposits or of the sediments from the two source 

areas, as shown in the triangular diagrams, are rather 

similar. Heterogeneity is characteristic of all. Perhaps the only readily visible difference is between the 

two sources of flood-plain sediments, as shown in figure 

5B : sediments from the Sierra Nevada seem to be better 

sorted (points closer to the sand-silt and silt-clay joins) 

than those from the Diablo Range. The relations of 

sizes and sorting to sources and depositional types is 

treated further in the section "Relations between particle-size measures and their bearing on the depositional 

history of sediments"; see especially figure 12. 

Another way of generalizing particle-size data is by 

summarizing the measures of central tendency-the 

mean, median, and mode-of the particle-size distributions. Only the median and modal diameters, which 

are more easily determined than mean diameters, are 

given here. 

The distribution of the median diameters ( M d) of 

the 305 samples is shown graphically in the top row of 

figure 6. The median "is that diameter which is larger 

than 50 percent [by weight] of the diameters in the distribution, and smaller than the other 50 percent" 

(Krumbein and Pettijohn, 1938, p. 229). Most of the 

median diameters fall in the range from 2p.. to 250J.t. 

More medians fall into the 8,u-16p.. intervals, the fine silt 

category, than into any other interval. This does not 

necessarily mean that 8J.l-16p.. is the most abundant median-particle range in the sediments of the area. It may 

reflect selective sampling: that is, perhaps more of the 

visually estimated "average" samples (p. C48) had 

median diameters in this size interval than in any other. 

A secondary maximum in the 125p..-250J.l interval suggests that, had the gravels and coarse sands in the section been recovered more completely, the distribution of 

Md values might have had two principal maxima, one 

in the fine-silt interval and the other in the sand-sized 

range. 

Where the distribution of median diameters gives a 

better impression of the "average" particle size, the 

distribution of modal diameters tells more about the 

MENDOTA 

CORE 

CANTUA 

CREEK 

CORE 

ALL SAMPLES <305> 

HURON 

CORE 

:OL..r.L • 1.4Lh 

0.5 4 62 1000 1 4 62 1000 1 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

SAMPLES <280> WHOSE MODES 

COULD BE DETERMINED 

·: i.IL 

2 4 62 1000 

l.a. 

1 4 62 1000 

lJL~ 1 4 62 1000 

~ ~ LM:EOIAL:;L MICR[w~ 

::E 

c( 

(/) 

LL. 

0 

a:: 

UJ 

CD 

::E 

24 62 1000 1 4 62 1000 1 4 62 

MODAL DIAMETER, IN MICRONS 

SAMPLES <261 > WHOSE QUARTILES 

COULD BE DETERMINED 

1000 

~·]JilL ~ J&~ 24 62 1000 24 62 1000 24 62 1000 

MEDIAN DIAMETER, IN MICRONS 

0 2 0 2 4 0 2 4 

QUARTILE DEVIATION (QD4>) 

·:~ -0.4 0 0.4 0.8 -0.2 l..IL 

0 0.4 -0.2 

~~ 0 0.4 

QUARTILE SKEWNESS 

FIGURE 6.-Measures of average size, sorting, and skewness in sediments from Mendota, Cantua Creek, and Huron cores, Los BanosKettleman City area. Measures of sorting (QD~) and skewness (Skq.~JQD~) 

defined on page C49. 

relative abundance of grain sizes. The modal si~:e interval of a sediment (National Research Council's size 

intervals in this study, see table, p. C49) is thE~ one 

that contains more material by weight tha.n any other. 

The distribution of 280 modal sizes is shown in the third 

row of figure 5. The modal sizes of the other 25 sampies could not be determined because too much of each 

sample was finer than l.OJ.l, and the distributions of sizes 
C12 MECHANICS OF AQUIFER SYSTEMS 

smaller than l.Op. were not determined. Fine sand 

(125p.-250p.) is the most abundant material in '7o samples, in spite of the fact that sediments whose median 

diameters fell into this category were poorly recovered. 

The abundance of fine sand is probably related to the 

relative ease with which this material, compared to particles of other sizes, is picked up and transported by 

running water (see fig. 8 and the accompanying discussion). 

Neither of these two measures of central tendency 

provides a perfect means of summarizing data on complex particle-size distribution. Ideally, in a normal 

frequency distribution, the median and mode coincide, 

but very few of the sediments considered in this report 

consist of particles whose sizes are distributed normally. 

The second row of figure 6 consists of histograms of the 

median diameters of the same 280 samples whose modal 

sizes are illustrated in the third row. One can readily 

see from these histograms that conclusions drawn about 

sediments from a single one of these measures are likely 

to 'be incomplete. 

SPATIAL DISTRIBUTION OF PARTICLE SIZES 

The differences between the parameters of particlesize distribution in the three cores are show~ in the 

bottom three rows of figure 6. The sediments from the 

Huron core are generally finer grained, less well sorted, 

and less skewed than the sediments from the Mendota 

core. Furthermore, the parameters of pavticle-size distribution seem to be more uniform (less dispersion, as 

shown by the histograms) in the Huron core. The particle-size properties of sediments from the Cantua 

Creek core are intermediate between those of sediments 

from the other two cores. Although this suggests a progressive change in a southeasterly direction toward finer 

grained, more poorly sorted, less skewed, and more uniform sediments, more comprehensive regional analysis 

of the sediments of the area, using electric logs and data 

from other core holes (Miller and others, in preparation 

as Prof. Pwper437-E), doesnotshowsuch a progressive 

trend. The differences between the cored sediments are 

local vather than regional features. 

Figure 7 shows the patterns of change in particle size 

with depth in the three cores. The resistivities of the 

sediments (from electric logs), as well as their median 

diameters, indicate particle size. The higher resistivities in these sediments are associated with the coarser 

sizes. Using the same symbols as in figure 5, sources 

a.re indicated by open circles (Sierra Nevada), dark 

circles (Diablo Range) , and crosses (mixed) . Types of 

deposits are indicated in the right column of each composite log. For composite logs that contain other information, namely the spontaneous potentials and generalized lithologies of the sediments, see the report by 

J olmson, Moston, and J\forris ( 1967). 

The Mendota core shows the most regular changes in 

particle size with depth. Consider the sediments from 

the bottom of the core to the top-the order in which 

they were deposited. Progressively coarser sediment 

( 1,500-1,200 ft) was deposited as the environment 

changed from a lake( ? ) to an alluvial fan and then to 

a flood plain. The flood-plain deposits became progressively finer ( 1,200-1,000 ft), and then coarser again 

as the source shifted from the Dia:blo Range to the 

Sierra (1,000 to about 750 ft). Above them was deposited the uniformly fine grained and lacustrine 

Corcoran Clay Member of the Tulare Formation (700-

625 ft) . Although too few median diameters were 

measured in sediments above the Corcoran in the Mendota core, the resistivities suggest that the sediments 

coarsen progressively between the top of the Corcoran 

and the present land surface. 

In the Cantua Creek core the variations in particle 

size are not so regular. Although the resistivity log 

suggests that the lacustrine (?) and flood-plain deposits 

penetrated in the lowest 300 feet of the hole are uniformly fine grained, the few median diameters measured in this part of the core do not suggest uniformity. 

Even more scattered is the distribution of the median 

diameters of the flood-plain deposits from the Sierra 

(1,700-980 ft) and of the alluvial-fan sediments from 

the Diablo Range ( 980 ft to the surface) . The resistivity log suggests a coarsening of the flood-plain 

deposits (1,100-1,000 ft) just before the change to 

alluvial-fan deposition. Too few median-diameter 

measurements are available to support this observation, 

however; the interval between 1,150 and 1,050 was not 

sampled because of an interruption in the coring schedule to correct an excessive drift of the hole away from 

the vertical. Within the alluvial-fan deposits, at about 

600 feet below the surface, lies 60 feet of well-sorted 

sand that was deposited here (perhaps as a beach) while 

the Corcoran Clay Member was being deposited elsewhere in the valley. Although the Cantua Creek core 

contains some short segments within which the particle 

size is fairly uniform, the general characteristic of the 

particle sizes in this core is diversity. Changes are not 

progressive but are mainly abrupt and local. 

The changes in the particle sizes of sediments in the 

Huron core are also mainly abrupt and local. As indicated in the histograms in figure 6, however, the median 

sizes in the Huron core are not scattered so widely as 

those in the other two cores. The pattern of mediandiameter distribution in the deltaic sediment at the bottom of the core suggests a gradual coarsening as the 

source changed from the Sierra to the Diablo Range 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C13 

MENDOTA 

CORE 

CANTUA CREEK 

CORE 

HURON 

CORE 

MEDIAN DIAMETER, 

IN MICRONS 

MEDIAN DIAMETER, 

IN MICRONS 

MEDIAN DIAMETER, 

IN MICRONS 

l 8 62 500 8 62 500 8 62 500 

• • 

• 

• 

• 

• 

• 

• 

• 

• 

• 

0 

• • 

• • 

• 

• 

0 

• 

• 

• 

• 

• 

• 

• 

• 

• • • 

I• • • 

+·· ~ 

500 

• 

• • 

• 500 

LLJ 

(.) 

<( 

LL. 

a:: 

::::> 

(/) 

-tq,++ RA+ o 

+-. 

•• • • • ++ •• 

0 

z 

<( 

OSf 0 ....J Oo 0 

0 0 ct;cP 

. :. . • • • ' .. • +. 

•• ~ 

0 

....J 

LLJ 

CD 

<9 .o + + •+t • • • . ' • . • • • • 

• ... : . &, •• . .. 

•• . .... • • ••• -~ • : • • • -: LA(?) 

EXPLANATION 

TYPE OF DEPOSIT 

AF, Alluvial fan 

FP, Flood plain 

LA, Lacustrine 

• ••• o •o 

0 

+ 

0 

0 

0 

0 

• 

• 0 

1000 

LA(?) 

1500 

• 

,. . . . .. • • • 

.a: I 

••• 

., 

•• • • • • 

.... 

.~ ... .-c 

• • •• • 

:· 

~ + 

~ ::f 

1000 

1500 

1-

LLJ 

LLJ 

LL. 

z 

SOURCE 2000 --LL---L-------v-----'---L- 2000 0 0 0 

00 2000 

00 

• Diablo Range 

o, Sierra Nevada 2200 ---L__L__---L_ _____ ___L _ ___J__ 2200 

+, Mixed 

FIGURE 7.-Variations in particle size with depth, Los Banos-Kettleman City area. Resistivity log is left column of each composite; 

range, from left to right, is 0-30 ohms m2jm. 

( 2,100-1,800 ft), but no such increase in grain size is 

indicated by the resistivity log of the same sediments. 

And although the resistivity log suggests a gradual 

coarsening of the alluvial-fan sediments between 1,800 

and 800 feet, the distribution of median diameters shows 

no such change. Both the resistivities and the median 

diameters suggest a progressive decrease in grain size 

from the lacustrine sands near 700 feet through the 

alluvial-fan sediments to the present land surface. 

In summarizing the particle sizes of the sediments of 

the Los Banos-Kettleman City area, one may say that 

their outstanding feature is diversity. This is an important factor in the compaction of the sediments. Had 

the sediments been consistently coarse grained, their 

response to increasing effective overburden loads would 

have been less than has occurred-coarse-grained sediments are compacted less per unit load increment than 

fine-grained sediments. Had they been consistently fine 

grained, their low permeabilities would have slowed the 

compaction to rates much less than those observed. The 

heterogeneous interlayering of compressible finegrained sediments and permeable coarse-grained sediments constitutes an aquifer system that responds efficiently to changes in overburden load by compacting 

rapidly and substantially. 

RELATIONS BETWEEN PARTICLE-SIZE MEASURES AND 

THEIR BEARING ON THE DEPOSITIONAL HISTORY OF 

SEDIMENTS 

Some sedimentologists have found that graphing 

particle-size measures against each other-especially 

average size against other measures-has helped them 

in understanding the hydraulic processes involved in 
C14 MECHANICS OF AQUIFER SYSTEMS 

the transport and deposition of clastic sediments. The 

work of some of these sedimentologists is reviewed in 

this section of the report. Then follow graphs of 

median diameter against measures of sorting, skewness, 

and the coarsest percentile for the sediments of the Los 

Banos-Kettleman City area. For those interested only 

in the direct description of the particle-size characteristics of the sediments, this section of the report is 

largely a digression that can be passed over quickly. 

REVIEW OF PREVIOUS WORK 

RELATIONS OF AVERAGE PARTICLE SIZE TO SORTING AND SKEWNESS 

In m'any waterlaid sediments, the deviation (sorting) 

and skewness of particle-size distributions seem to vary 

in systematic and consistent ways with the average 

diameter. Inman ( 1949) pointed out these variations 

in a summary of studies of shallow-water marine sands 

and silts (fig. 8) and presented convincing evidence and 

arguments that they reflected the hydrodynamic relations that exist between running water and sediment 

particles. 

16 62 250 1000 

\ ~ \ \ Q> 

3 ..._ 

0' \ \ 1.5 z ~ \' 0 

~\ i= 

" c( 

z 

"~ > i= LLJ 

0::: 2 / 0 

0 '\ ........._ Red Sea"'>-'/ LLJ fl) ..J Cape Cod/~ "'-.... ____ _... i= 

Bay 0::: 

0.5 c( 

:::::1 

0 

0 

A 

........ 

~ -0.2 ~ 0 -:e. 0 oO c:;,o 

.2 ~ 

fl) fl) 

fl) fl) -0.2 LLJ LLJ 

z z 

:i: :i: 

LLJ LLJ ~ ~ 0.6 fl) fl) -0.4 

16 62 250 1000 

B 

MEDIAN DIAMETER, IN MICRONS 

FIGURE 8.-Relation of median diameter to (A) sorting and 

(B) skewness in shallow marine sediments. Modified after 

Inman (1949, p. 52) ; chief modification is addition of 

skewness data from Buzzards Bay (Hough, 1940, p. 2!3-26). 

Other data sources : Cape Cod Bay (Hough, 1942, p. 21), 

Barataria Bay (Kru'mbein and Aberdeen, 1937, p. 8-9), 

Red Sea (Shukri and Higazy, 1944, p. 62-63). So and Sk 

are sorting and skewness coefficients of Trask (1930, 

p. 594), based on quartiles. 

Sorting reflects the relative ease with which particles 

of different sizes are picked up and transported by 

water. The best sorted sediments are those whose 

median diameters fall into the category of fine sand 

(125p.-250JL). Inman states (1949, p. 61) that fine sands 

are hydrodynamically unique from all other sizes in that: (1) 

they are moved by weaker currents than grains smaller or 

larger than themselves; (2) once moved they do not have as 

great a tendency to go into suspension as do smaller grains; 

and (3) they are more readily carried into suspension than 

larger mater:i.al. 

Because materials both coarser and finer than fine sand 

are more difficu:lt to move rand since very :fine material is readily 

carried into suspension, bottom sediment in the process of transportation tends to become progressively better sorted as its 

median diameter nears 0.18 mm [180tt]. Sediments with median 

diameters either larger or smaller than 0.18 mm tend to be 

more poorly sorted; the tendency toward poor sorting being 

more pronounced for :fine sediments. This mray be accounted 

for by the fact that the fluid does not as readily differentiate 

between the smaller diameters. 

Skewness seems to reflect the different means by which 

water transports particies of different sizes. In sands 

and finer materials, as suggested by figure 8B, the sediments with the least skewed particle-size distributions 

(log 1 oSk ,_,o) seem to be the sands and fine silts (Md 

125p.-1000p. or finer than 16~-t). The most skewed distributions are found in intermediate mixtures of sand and 

finer rna terials ( M d 30p.-60p.) . Such relations between 

particle size and skewness might be due to the fact that 

sand in most streams of moderate size (and presumably 

in currents in shallow seas) is transported as bed loadrolled and bounced along the bottom-and that materials finer than sand are usually carried in suspension. 

The less skewed sediments mav have been transported 

by one means only, either as ~d load or in suspension. 

The more skewed intermediate sediments may represent mixtures of material transported by both means 

and, for: some reason, deposited together. 

Since Inman published these curves and his interpretations of them, many more studies of the size distributions of sediments have confirmed the existence of the 

relations of average diameter to sorting and skewness. 

For example, see the papers by Folk and Ward (1957), 

Fiichtbauer and Reineck (1963, p. 298), Griffiths 

(1951), Inman and Chamberlain (1955), Shumway 

( 1960, p. 665), and W alger ( 1961). 

CM DIAGRAMS 

Another graphical method of portraying the particle-· 

size distributions of sediments has been proposed by 

Passega (1957, 1960, 1964). He focuses attention on the 

coarser half of a sediment by graphing the median diameter against the first (coarsest) percentile, which he 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C15 

calls "0." The first ·percentile is used as a measure of 

the competence of the depositing medium, and the 

median diameter represents the average grain size of the 

material deposited. By using parameters based only on 

the coarser half of a sediment, one considers the part of 

the sediment that reflects most sensitively the carrying 

and sorting capacities of the transporting and depositing media. 

An example of Passega's graph, which he calls a "CM 

diagram" is shown in figure 9. He has suggested that 

aqueous sediments might fall into characteristic patterns according ~to the way in which they were transported or deposited. The solid-line sinuous pattern 

la:beled N 0 PQ RS is characteristic of sediments carried 

by rivers and other tractive currents. The pattern enclosed by the dashed line seems to be characteristic of 

the deposits of turbidity currents; sediments deposited 

slowly in still water fall in or near the circular pattern. 

The pattern NOPQRS, derived empirically from 

modern riverbed sediments in the United States and 

from Tertiary sediments in the United States and Italy, 

implies that sediments associated with tractive currents 

fall into a family of curves (fig. lOA) that shows the 

effect of hydrodynamic sorting. In fine-grained tractive 

sediments ( RS segment of the pattern), some fine sand 

will always be present (if available to the stream) regardless of how fine the rest of the sediment might be. 

Sediments that fall into the Q R segment ( M d in the 

range lOOp. to 200.u) are the best sorted; they fall closest 

to the O=lJ/d line in figure 9, and their curves in figure 

lOA have the steepest slope. As the stream increases in 

competence it is able to transport coarser particles (PQ 

segment) ; but the bulk of the sediment tends to consist 

of particles of the optimum hydrodynamic size-125p.-

500p.. Provided that the appropriate particle sizes are 

available, these three segments-RS, QR, and PQ, 

(/) 

z 

0 

0:: 

~ 1000 

~ 

~ 

LLi 

...J 

~ 250 LLI 

u 

0:: 

LLI 

a.. 

tn 

0:: 

i:i: 

62 

4 16 62 250 1000 

MEDIAN DIAMETER, IN MICRONS 

FIGURE 9.-CM patterns. After Passega (1960, p. 1734). 

LLI 

N 40 

en 

c 30 LLI 

~ 20 u 

iS 10 z 

z 5 <( 

:::c 

1-

62 250 1000 

ffi 1l__ _ _L_ _ __L_ _ _L__3L_ll_.L.-l___._---l.----Ln...l-~ 

(/) 

0:: 

<( 

A 

8 50~~~~~~~~~~~--,--, 

1- 40 z 

~ 30 

ffi 20 a.. 

~ 10 

i= 

:5 5 ::::> 

~ 

::::> 

u 1L_ _ _L__~~~_L_L~~~~~~ 

16 62 250 1000 

B 

PARTICLE DIAMETER, IN MICRONS 

FIGURE 10.-Particle-size-distribution curves (probability scale) of sediments deposited by (A) tractive currents and (B) turbidity currents, implied 

by Pass~ga's CM patterns. 

should be characteristic of all tractive sediments. They 

reflect the same hydrodynamic circumstances as those 

Inman used to explain the relations between median size 

and sorting (fig. 8A). 

The 0 P and N 0 segments are not characteristic of 

all tractive sediments but are said by Passega to represent special conditions. "In the 0 P part, the proportion of rolled grains increases, and the 0 N segment 

corresponds almost uniquely to a deposit of rolled 

grains" ( Passega, 1960, p. 1735). These two segments 

did not appear in the sediments transported by the 1\!ississippi, Enoree, and Niobrara Rivers or in the other 

tractive sediments described by Passega in 1957 (p. 1954, 

1961-1963). Apparently, these segments of the pattern 

represent winnowed or reworked sands and gravels or 

sediments with restricted sources. 

Passega also suggested that points representing the 

'deposits of turbidity currents might fall into a characteristic pattern parallel to the C = M d line (enclosed 

by dashed lines in fig. 9). The distance of the pattern 

from the C=Md line is said to be a direct function of 

the density of the current. This implies that the cumulative curves representing the coarser halves of samples 

of sediments deposited by turbidity currents of similar 

density are parallel to one another (fig. lOB)-that is, 

as long as the current density remains constant, the 

sorting of the coarser half remains constant regardless 

of the size of C or M d. As represented in a OM dia-
Cl6 MECHANICS OF AQUIFER SYSTEMS 

TYPE OF DEPOSIT 

64,000 o, Mudflow .b. 

(/) 

z .. ~ 16,000 0, Braided stream 

S:? 

~ 

~ 4000 

LLi 

...J 

i= 

z 1000 LLJ 

(.) 

0::: 0 LLJ 

a.. ':50 0 

~ 0::: 

u:: 0 

62 0 

4 16 62 250 1000 4000 

MEDIAN DIAMETER, IN MICRONS 

FIGURE 11.-CM patterns of modern surficial alluvial-fan 

deposits, Los Banos-Kettleman City area. After Bull (1962, 

p. 214). Tractive pattern enclosed by solid line; mudflow 

deposits inside dashed line. 

gram, sediments with poorer sorting are associated with 

currents of greater density (Passega, 1957, p.1967). 

OM patterns prepared by Bull ( 1962) from analyses 

of sediments deposited in 1957-58 on alluvial fans in 

the Los Banos-Kettleman City area add support to 

Passega's ideas. Bull found (fig. 11) that samples of 

stream-channel and braided-stream deposits fell into the 

PQR segment of a tractive pattern. Mudflow deposits 

fell into a pattern nearly parallel to the C=M d line-as 

one might have predicted from Passega's observations 

on what he supposed were turbidity-current deposits. 

The distance of the mudflow pattern from the C = M d 

line supports Passega's proposed relation between current density and sediment sorting. 

INTERRELATIONS OF PARTICLE-SIZE MEASURES IN CORED 

SEDIMENTS 

Figure 12 s~ows graphs of median diameter against 

the coarsest percentile (C), sorting, and skewness for 

the flood-plain 1and alluvial-fan deposits of the Los 

Banos-Kettleman City area. Not included in the 

graphs are samples of sediments that are cemented or 

that contain interlaminations or other inhomogeneous 

mixtures of different-sized particles. Lacustrine sediments are not included because the identification of 

some of the deposits as lacustrine is questionable. 

Deltaic sediments are not included because too few samples of homogeneous 1naterial are available to show 

significant variations in the particle-size measures. 

Quartile deviation ( QD <t>) is used to represent sorting. 

Two measures of skewness are used-Bow ley's 1neasure 

(Skq<t>/QD<J>, used so far in this report) and a measure 

of absolute skewness; Skq<J>. The relation of Skq<t> to 

the log 10 Sk measure is shown in the two calibrated 

FLOOD 

PLAIN 

ALLUVIAL 

FAN 

16,000 

w· 

...J 

i=(/) 4000 •• zz 

LLlQ Uo::: 

o:::u 

LLJa..~ 

1-z (/)_ 

0::: 

u:: 

:e. 

~ 

LLJ~ ~--~ 

:::l(/) 

...J(/) 

Ow (/)z 

fll5; 

<(LLJ 

:t: 

(/) 

0 0 

1000 .. : ~QO 

0 o oM 250 Cb c! o• ~ 

• 8• ·~ 62 

16 

0.8 

0.6 

0.4 

0.2 

• 0 

'b+ 0 ~~ 

cf 

4 16 62 250 1000 

0+ oo. 00 

~ ~· cD. 0 ••• o.o-. oo ·~ 0 • 0 • Ofb • c!'o o .. + 0 Oeo tP •o • 0 o8 8. • 0 0 

-0.2 

1.6 

1.2 0 o• 

0 0 • 

0.8 • • • e O.o 0 

0 .&e • g •-lo 0.4 ~o+~ ~ o_.~ cPCP • 0 dO •o ~,(~ oo • 

-0.4 

-0.8 

4 16 62 250 1000 

4 16 62 250 1000 

- I -

..... ~ 

-·$.,,.., .... -

1-'=··~"·· ·'., .- !·· 

• 

' 

.. ,. 

• . . • • ., . . ·-....:: -,. .. , .. J." ~., I .... • 

... ,, . ... -. 

• 

.. ... 

• • •• • 3-:._:. ' • • • • ~~r:~· ...... .. ,. . . . •• • • • • •• 

4 16 62 250 1000 

MEDIAN DIAMETER, IN MICRONS 

0 

EXPLANATION 

SOURCE 

• Sierra Nevada Diablo Range + Mixed 

FIGURE 12.-Median diameter against coarsest percentile, sorting, 

and skewness in flood-plain and alluvial-fan sediments, Los BanosKettleman City area. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C17 

ordinates of figure 8B; note that positive values of 

Skq'rf> correspond to negative values of log 10 Sk. These 

measures are defined in more detail on pages C49-

C50. 

FLOOD-PLAIN SEDIMENTS 

The CM pwttern for the flood-plain sediments of the 

Los Banos-Kettleman City area (upper row, left col., 

fig. 12) at first glance seems to be a scatter of points 

roughly parallel to the C = M d line. Judging from the 

CM pattern, the sorting is slightly poorer in the fin,er 

sediments (points generally farther from the C = M d 

line) , but the degree and variability of the sorting of 

the coarser halves of the sediment do not change 

markedly with median diameter. A closer look at the 

pwttern shows most of the scatter to be related to the 

s~mples of sediments from the Sierra Nevada (open 

circles). The distribution points representing floodplain sediments from the Diablo Range (dark ci~cles)­

except for the two samples having C values slightly 

greater than 1,000p. and M d values slightly less than 

62p.-could be interpreted as the PQ RS segments of a 

tractive pattern. These observations suggest some kind 

of source-related control on the regularity of the relations between median diameter and sorting: perhaps a 

more uniform mode of transportation from the west 

side of the valley, or some differences in the disintegration and weathering of the different rock types represented on the two sides of the valley. 

The relation of median diameter to quartile deviation 

in the flood-plain sediments is shown in the second row, 

left column, figure 12. Here also, the sediments derived from the Sierra Nevada show the greater scatter, 

but not as much so as in the CM pattern. The sediments 

fall generally into two groups, one of fairly well sorted 

sands and another of less well sorted finer sediments. 

No consistent variations with size or source area can be 

seen in the graphs of median diameter against skewness 

(third and fourth rows, ·left col., fig. 12). 

The lack of clear relations between the particle-size 

measures probably reflects the diversity of the sediments 

that have been included in the category of flood-plain 

deposits. The category is a broad one, including sediments laid down in the channels of perennial streams as 

well as on the overflow lands associated with the valley 

drainage system under more humid conditions than 

exist today. This means that pond and small-lake deposits have been lumped with the deposits of more active 

fluvial systems. 

ALLUVIAL-FAN SEDIMENTS 

The alluvial-fan deposits, which came from a single 

source area and were deposited under a more uniform 

set of conditions than the flood-plain sediments, show 

more consistent relations between the particle-size 

measures. 

The CM pattern of the alluvial-fan sediments (upper 

row, right col., fig. 12) seems to correspond to the RS 

segment of a tractive pattern. The sorting of the 

coarser half of the sediments varies directly with the 

median diameter; or, expressing the relation another 

way, regardless of the average particle size (in the Md 

range from 1p. to 250p.), some fine to medium sand is 

always present. 

A PQ segment is probably part of the complete CM 

pattern of the alluvial-fan deposits, but no particle-size 

analyses of the appropriate sediments were made. The 

coarsest sediments were not availaJ:>le for analysis (p. 

C48). From visual inspection of the ·coarse alluvialfan sediments that were recovered but not analyzed, I 

have the impression that their C values can be as coarse 

as 16,000,u, whereas their median diameters lie fairly 

consistently in the fine- to medium-sand range, 125,u 

to 500,u. Had the coarser samples been analyzed, a PQ 

segment probably would have appeared in the pattern. 

This supposition is reinforced by Bull's CM patterns of 

coarser grained alluvial-fan sediments (fig. 11). 

The relation between median diameter and quartile 

deviation in the alluvial-fan sediments (second row, 

right col., fig. 12) is similar to that in the flood-plain 

sediments, except that the sorting of the finer grained 

alluvial-fan sediments seems to be poorer. The mean 

quartile deviation of sediments with medians finer than 

62,u is about 2.0 in the alluvial-fan deposits, compared 

with 1.5-1.7 in the flood-plain deposits. Whereas the 

sorting of the coarser half of the sediments seems to 

change progressively with M d, the quartile deviation 

shows no consistent variation in the M d range from 4,u 

to 62,u. 

The CM pattern and grnrph of Jl d versus Q D"' for lthe 

alluvial-fan sediments may be partly misleading. 

Many (but certainly not all) of the fine-grained 

alluvial-fan sediments contain day and silt that were 

apparently transported and deposited in sand-sized aggregates (fig. 4). Many of these aggregates must have 

been broken up during size analysis and were recorded 

as smaller particles than they were when deposited 

(Bull, 1964c). This would affect the measurement of 

M d and Q D"' but not the measurement of C. That is, 

some of the sediments probably were better sorted and 

had coarser medians when deposited than is indicated 

in the graphs, but they still should fall into the RS 

segment of a CM pattern. 

Skewness seems to vary fairly consistently with M d 

in the alluvial-fan sediments of the Los Banos-Kettleman City area. The patterns of both relative and absolute skewness (bottom two rows, right col., fig.12) show 
Cl8 MECHANICS OF AQUIFER SYSTEMS 

a progressive increase in skewness between M d values 

of 4p. and 62p.. Combining the impressions from both 

measures of skewness, the alluvial-fan sediments are 

least skewed when their median diameters fall into the 

coarse-clay to fine-silt or fine- to medium-sand categories ( 2p.-8p. or 125.p.-500p.). Mixtures of sand and 

finer materials (medians near 62p.) have the most skewed 

distributions. This is similar in general to the relations between median size and skewness summarized in 

figure8B. 

CLAY MINERALS AND ASSOCIATED IONS 

CLAY MINERALS AND THEIR ASSEMBLAGES 

The principal clay mineral in the Los Banos-Kettleman City area is montmorillonite. Subsidiary clay 

minerals present are illite and chlorite, and lesser 

amounts of a kaolinite-type mineral, mixed layer montmorillonite-illite, and a low-grade illite-montmorillonite mixture. The distribution of clay minerals in 

the four principal cores is shown in figure 13. The clay 

minerals in Recent sediments carried or deposited by 

the streams that flow into the area from the Diablo 

Range are shown in figure 14. 

The detailed results of the clay-mineral analyses of 

101 sam.ples-85 from the deep core holes and 16 from 

streams and alluvial-fan deposits to a depth of 70 feetare given in tables 11 and 12. Assuming that the 85 

samples are representative, the average clay-mineral 

composition of the sediments of Pliocene to Recent age, 

of tl1e Los Bano·s-Kettleman City area is approximatelyClay minerals Percent 

Montmorillonite -------------------------- 70 

Chlorite --------------------------------- 10 

Illite ------------------------------------ 10 

Kaolinite-type mineraL___________________ 5 

Mixed-layer montmorillonite-illite and lowgoode il:lite-ruootmorillooite______________ 5 

The identification criteria for these clay minerals and 

the means of estimating their relative proportions are 

given on pages C67-'C71. 

Two principal assemblages of clay minerals are found 

in the sediments of the area. Most of the stream and 

subsurface sediments contain an assemblage consisting, 

in decreasing order of abundance, of montmorillonite, 

type-B chlorite, illite, kaolinite-type mineral, and lowgrade illite-montmorillonite (figs. 13, 14). This assemblage seems to be derived mainly from the sedimentary 

and volcanic rocks (Cretaceous through Pliocene in 

age) that crop out along both sides of the San Joaquin 

Valley and from the weathered granitic and metamorphic rocks that crop out in the Sierra Nevada and its 

foothills. 

The second assemblage-illite, mixed-layer montmorillonite-illite, type-A chlorite, and subsidiary montmorillonite-is found only in Little Panoche Creek and 

its alluvial fan. I suspect that this assemblage is derived mainly from the slightly metamorphosed and 

locally sheared graywackes and shales of the late Mesozoic Franciscan Formation. It resembles closely the 

assemblage of clay minerals found in weathered rocks 

of the Franciscan Formation in the San Francisco area 

( Schlocker, Julius, oral commun., 1962). The proportion of the Little Panoche drainage basin underlain by 

the Franciscan Formation-41 percent-is more than 

twice the proportion underlying the drainage basins 

of the other principal streams in western Fresno County 

(Davis, 1961, p. B-7). Another 34 percent of the 

Little Panoche drainage basin is underlain by continental deposits derived mainly from the Franciscan 

Rormation (W. B. Bull, written commun., 1964). The 

change in clay-mineral assemblages at. some depth between 230 and 375 feet in the Oro Lorna core (fig. 13) 

marks the extension of the Little Panoche Creek fan to 

this point in the valley. 

The predominance of montmorillonite i~ the first assemblage, and in the assemblages in the sediments that 

lie beneath the other areas of land subsidence in central 

California, is an important factor in the compaction 

behavior of the sediments. Experimental studies, summarized in the earlier paper in this series (Meade, 1964, 

fig. 4), have shown that montmorillonitic clays are more 

compressible than illitic or kaol·initic clays. The presence of montmorillonites in these sediments probably 

contributes to the intensity of their response to changes 

in effective overburden load. 

SOURCES OF CLAY MINERALS 

SOURCES OF MONTMORILLONITE 

Comparison of figures 3 ·and 13 shows tJhat the claymineral assembl·ages derived from both sides of the 

valley are virtU!ally identical. Montmorillonite predominates in both. 

The soils and sedimentary rocks of the Dia;blo Range 

source area must contain a large proporiion of montmorillonite, judging from the clay-mineral assemblages 

being carried by most of the streams entering the Los 

Banos-Kettleman City area from the southwest (fig. 

14). Some of this montmorillonite may be forming in 

the soils, and some of it may represent the alteration of 

volcanic m-aterial within the sedimentary rocks. Vulcanism was widespread and frequent in central California during Mesozoic and Tertiary times (Jenkins, 

1948; Lerbekmo, 1961; Taliaferro, 1943, p. 150); vol-
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA 019 

w 

(.) 

<( 

LL 

a:: 

:::> 

(/) 

Cl 

z 

<( 

...J 

3: 

0 

0 

500 

u1 1000 

al 

1-

w 

w 

LL 

z 

:i 

1-

Q.. 

w 

Cl 

0 5 10 0 

CLAY MINERALS 

(ESTIMATED PARTS PER TEN) 

5 10 0 5 10 

ORO LOMA CORE MENDOTA CORE CANTUA CREEK 

CORE 

0 

500 

1500 

EXPLANATION 

Montmorillonite 

-

I2ZI 

Mixed-layer montmorillonite-illite 

D 

Illite 

Low-grade illite-montmorillonite 

§§! 

Chlorite 

Kaolinite-type 

-

mineral 

Chlorite and kaolinite-type 

-

mineral 

(undifferentiated) 

0 

• 

500 

1000·----

-!!iii!!!! 

liWml 

lmf:!fll.l 

mil 

1500 

lHm 

IHfll 

ml 

~ 

-1 

2000 -

0 5 10 

HURON CORE 

0 

500 

1000 

FIGURE 13.-Clay minerals in cored sediments, Los Banos-Kettleman City area. Trace amounts, given in table 11, not 

illustrated. Where two analyses were made less than 10 feet apart in cores, they were combined and illustrated as a 

single analysis. Twenty-five of illustrated analyses for Mendota and Huron cores were made by J. C. Hathaway, 

H. C. Starkey, and G. W. Chloe. 
C20 MECHANICS OF AQUIFER SYSTEMS 

Los Banos 

• 

120°30' 120°00' 

Mendota• 

MENDOTA 

(14/13-1101) (_ 

Kerman 

• / 

EXPLANATION 

///7/7 36°30' Boundary of deformed rocks 

® 

Core-hole location 

• 7 

Sample location 

Number corresponds to that 

in table 12 

Montmorillonite 

-

~ 

Mixed-layer montmorillonite-illite 

D 

Illite 

~ 

Chlorite 

Kaolinite-type 

-

mineral 

!mml 

Chlorite and kaolinite-type 5 mineral (undifferentiated) 0 5 

36°00' 

·--~ 

.. :~-. 

\ 

\ 

'""' ... -----· .. ---'\..~ 

·-,~ 

Five Points 

• 

HURON 

\..':1 

'\._ 

(19/17-22Jl, 2) 

® 

Westhaven 

•Huron 

/ 

/ 

\ .. .""- .. ..---lc_---

I · .. "'7"- .. ·--.........·· 

I ( ,-r···/ .· 

8ig \(. 

Oloo ( 

~~~ ~~~ ( ~I \. " Stratford f 

Tulare 

Lake 

Bed 

Kettle_man 

• City 

FIGURE -1.4.-Sampling sites for clay minerals in Recent surface alluvial sediments, Los Banos-Kettleman City area. Samples 3, 4, 7, 

and 11 collected by W. B. Bull. 

canic minerals and rock fragments are significant constituents of many of the sediments deposited then. 

Much of the 1nontmorillonite in the valley sediments 

from the Diablo Range may well have heen derived 

from material that was deposited in and with older sedi1nents as volcanic debris, aJtered to montmorillonite, 

and then eroded and redeposited as montmorillonite in 

the valley. However, no clay-mineral analyses of soils 

and rocks of the Diablo Range source area are available 

to substantiate this supposition. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C21 

A little montmorillonite has formed in the sediments 

from the Diablo Range since they were d~posited. 

Some of the sand grains, especially those in the lowest 

500 feet of the Mendota core, are coated with a m'aterial 

that colors them pale blue. Similar material has been 

identified in Pliocene sandstones from central California as montmorillonite that is derived from alteration of 

the volcanic detritus of andesitic composition that comprises large proportions-in some places nearly all-of 

these sandstones (Lerbekmo, 1957, 1961). In the sediments of the Tulare Formation and younger alluvium 

from the Diablo Range, however, the volcanic detritus 

is always mixed with such nonvolcanic constituents as 

serpentine and reddish chert, suggesting that these sediments are mixtures of reworked older volcanic sands 

and other materials. Because the coatings cover nonvolcanic as well as andesitic grains in the cored 

sediments, the coatings must have formed since the 

sediments were deposited. · 

Although montmorillonite has been formed within 

the sediments, no progressive increase in montmorillonite (relative to the other day minerals) with depth 

of burial is evident (fig. 13). Perhaps the transformation of volcanic material to montmorillonite is not restricted to the sediments buried in the valley but is 

going on in the sediments and soils of ~the Diablo Range 

source areas at a similar or even greater rate. 

'I'he source of the montmorillonite in the sediments 

from the Sierra Nevada is uncertain. According to 

R. J. Janda (written commun., 1964, 1965), the principal clay mineral in the soils and alluvium of the upper 

San Joaquin River basin is kaolinite; subsidiary minerals are halloysite, vermiculite, montmorillonite, and 

illite. In many of these soils and sediments, montmorillonite is totally absent. Assuming that this represents the assemblage of clay minerals that the weathering of the granitic rocks in the Sierra Nevada has 

produced since Pliocene time, why do the Sierra-derived 

sediments of the valley contain an assemblage of clay 

minerals that is dominated by montmorillonite~ 

One possible source of the montmorillonite is the belt 

of metamorphic rocks in the western foothills of the 

Sierra Nevada. Perhaps montmorillonite has formed 

in the soils developed on these rocks and has been contributed to the streams that drain the Sierra in amounts 

sufficient to dilute the kaolinite-dominated assemblage 

contributed by the granitic terrane of the Sierra proper. 

Another possible source of the montmorillonite is the 

Coast Ranges. The Sierra-derived sediments were 

designated as such on the basis of the assemblages of 

sand- and pebble-sized constituents. I assumed that the 

clay constituents of the same sediments also came from 

the Sierra. This may not necessarily be so. In the 

Los Banos-Kettleman City area, the cored sediments 

whose source ~s design31ted as ~ierran were deposited on 

flood plains, in lakes, or in deltas. It is entirely possible 

that any, or all, of these deposits oontain clay from the 

Diablo Range, even though none or very few of the 

sand and gravel constituents of these sediments came 

from the west. In the Tulare-Wasco area the fact that 

the shallow-marine sediments contain proportionately 

more montmorillonite than the alluvial-fan sediments 

(figs. 17, 24) may be indicative. That is, the marine 

deposits may have received day that origin31ted in the 

Coast Ranges and was moved in suspension to the east 

side of the shallow sea that occupied the southern part 

of the San Joaquin Valley at the time. The predominant clay mineral in the 'alluvial-f,an deposits of 

the Tulare-Wasco area, however, is also montmorillonite. And, because these alluvial-fan sediments must 

have been derived exclusively from the Sierra., all the 

montmorillonite cannot have come from the Coast 

Ranges. 

One must consider also that the montmorillonite in 

the Sierra-derived deposits may have formed hy the 

alteration or transformation of other minerals soon 

after th~y were deposited in the valley. At least two 

possible sources, kaolinite and biotite, are worth 

considering. 

Montmorillonite may have been 'formed from the 

kaolinite, either in soils that developed on the alluvial 

fans or as a diagenetic transformation in the high-pH 

environment of the valley sediments (see the pH measurements listed on p. C72 and in tables 11-13) . The 

cored sediments, however, contain no evidence of such 

changes in the form of increasing proportions of montmorillonite and decreasing kaolinite with increasing 

depth of burial. The mechanism of such a transformation, involving a change from a two-layer structure to 

a three-layer structure, would seem to require energies 

that are not generally available in soils or in sediments 

buried under a few ~tens of feet of overburden. The degree of crystallinity of the kaolinite, on the other hand, 

is poor, and perhaps the transformation to montmorillonite could t~ake place at low energy levels. 

The montmorillonite may have been formed from 

biotite in the sequence: biotite~vermiculi~montmorillonite. Vermiculite is a common product of the 

weathering of biotite in California soils (Barshad, 

1948). And montmorillonite could easily he formed 

from vermiculite with little change in the structure of 

the basic mineral lattice-the two minerals are so similar that distinction between them is often difficult. Biotite, in sand -sized flakes and books is a common constituent ( 2-5 percent) of the Sierra-derived sedimentsprobably more biotite than kaolinite, in terms of total 

sediment, is contributed by the Sierra to the valley. AI-
C22 MECHANICS OF AQUIFER SYSTEMS 

teration of some of the biotite (especially in the alluvialfan sediments of the Tulare-Wasco area) from greenish 

black to golden yellow indicates that it has lost some of 

its identity as biotite. Vermiculite has been identified 

in the clay-mineral fractions of some of the sediments of 

the Pixley core from the Tulare-Wasco area, and it may 

be present in sediments in some of the other oores as 

well (but impossible to distinguish in the presence of the 

much greater proportions of montmorillonite). But 

no progressive alterftltion of biotite or change from vermiculite to montmorillonite has been observed with increasing depth of burial. 

The question of the origin of the large proportions of 

montmorillonite in the valley sediments from the Sierra 

Nevada-in both the Los Banos-Kettleman City and the 

Tulare-Wasco areas-remains unanswered. One oannot choose the best hypothesis or combination of hypotheses on the basis of the evidence that is now 

available. 

SOURCES OF OTHER CLAY MINERALS 

Mixed-layer montmorillonite-illite seems to be derived entirely from the Diablo Range, probably from 

rocks of the late Mesozoic Franciscan Formation. It is 

a significant constituent of sediments in modern Little 

Panoche Creek, in the upper third of the Oro Lorna 

core, and in the coarse lens of sediment at depths between 1,000 and 1,200 feet in the Mendota core. 

Illite and chlorite are ubiquitous, but variations in 

their crystallinity are helpful in delineating their 

sources. Well-crystallized illite and type-A chlorite 

occur in conjunction with mixed -layer montmorilloniteillite, and seem to be derived from the Franciscan Formation. Type-B chlorite and less well crystallized illite 

seem to be derived mainly from Cretaceous and Tertiary 

sediments of the Diablo Range and Sierra Nevada 

foothills. 

The kaolinite-type mineral or minerals could have 

come from many sources. Three possible sources of 

aluminum-rich kaolinite are weathered silicic intrusive 

rocks of the Sierra Nevada, hydrothermal alteration 

zones associated with quicksilver deposits in the Diahlo 

Range (Eckel and Myers, 1946; Yates and Hilpert, 

1945), and "ana uxitic" Eocene sediments along the west 

side of the northern San Joaquin Valley (Allen 1941 · 

B . ' ' nggs, 1953, p. 39-41). Serpentine minerals have 

kaolinite-type structures, and they may be present in 

the samples; serpentine bodies crop out in the drainage 

basins of all the major creeks that flow from the Diablo 

Range into the Los Banos-Kettleman City area. 

An intriguing possibility is that some of the kaolinitetype material is derived from the weathering of chlorites. Nelson and Roy (1954, 1958) have shown that the 

polymorph of chlorite stable at low temperatures might 

have a kaolinite structure, and a mineral with a chloritic 

composition and kaolinite structure has been found in a 

low-temperature environment by Sigvaldason and 

White (19·61, p. D-117, D-119). Considering that 

much of the chloritic material in the Tulare Formation 

and younger sediments of the valley represents chlorite 

from older sediments that has been through two or more 

periods of degradational weathering, the sequence of 

minerals represented as .A., B, and 0 in figure 40 may 

represent a gradation from well crystallized 14-A 

chlorite to poorly crystallized 7-A chlorite. 

TOTAL CLA Y·MINERA.L CONTENT OF SEDIMENTS 

The total amount of clay-mineral material in the 

cored sediments of the Los Banos-Kettleman City -area 

is about 15 percent, and the total amount of montmorillonite is about 10 percent. 

This estimate was derived by a combination of visual 

examination and particle-size analysis. The visual 

examination was made with a petrographic microscope 

and an oil-immersion lens ·and consisted of point counts 

(100 points each) of specimens of 20 fine-grained sediments that had been stained with a mixture of malachite 

green and nitrobenzene. Malachite green stains clay 

minerals selectively without staining nonclay minerals 

(Mielenz and King, 1951, p. 1217). The point counts 

yielded a rough estimate of the proportion of claymineral material in each of the 20 sediments. 

Particle-size analyses were also made for these 20 

sediments-the core-hole sediments in table 6. The 

particle-size analyses were compared with the .point 

counts to determine the percentile (particle diameter) 

that corresponded to the proportion of clay minerals 

estimated visually: say, for example, the visually estimated proportion of clay minerals was 40 percent, then 

the particle diameter that was coarser than 40 percent 

of the sediment was taken from the size-distribution 

curve. For the 20 sediments, the geometric mean of 

these particle diameters was 3.0p. ( 8.4<f>) and their 

standard deviation was about 1.5p. ( 0. 7 <f>) . The weight 

percent finer than 3.0p., therefore, was taken as the proportion of clay-mineral material in a sediment. 

The next step consisted of determining the percents 

finer than 3.0p. in the 305 sediments whose particle sizes 

were discussed in the previous section (listed in table 

5) . The mean of these was 20 percent. This estimate 

was adjusted to 15 percent to allow for the coarser 

sediments that were not recovered during the coring 

operations. 

IONS ASSOCIATED WITH CLAY MINERALS 

The principal ions adsorbed by the clays and in 

waters associated with the clays are calcium, magne-
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C23 

sium, sodium, bicarbonate, sulfate and chloride. These 

are listed in tables 11 and 12; the procedures used 

in their determination are described on pages 

C71-C72. 

Figure 15 represents the cations adsorbed by the clays 

in sediments from the four principal streams and the 

four core holes. The percentages illustrated were adjusted by subtracting the equivalent of the total anions 

from the total calcium ions; this involves the assumptions (not necessarily true) that all the soluble salts in 

these sediments are calcium salts and that none of the 

anions are adsorbed by the clays. The accuracy of figure 15 is subject to the doubts and limitations discussed 

below, but -the general picture is valid. 

The adjusted sums of exchangeable cations in these 

samples, with one exception, are greater than the determined cation-exchange capacities. Several hypotheses 

to explain this disparity are listed below, but one cannot 

choose between them on the strength of the available 

evidence. 

1. The adjustment is only a partial correction because 

the solubility of the principal salts in these sediments, calcite and gypsum, is greater in NH4Cl 

solution (in which the adsorbed cations were determined) than in hot water (in which the soluble 

anions were determined) . 

2. The cation-exchange capacities, as determined, may 

be lower than the actual capacities because some of 

the ammonium ion that was added to displace the 

naturally held exchange cations may have been 

fixed so strongly on the clays that it was not removed by the alcohol-distillation procedure used 

in the analysis (Richards, 1954, p. 20). 

3. The disparity may be related to differences in pH 

between the natural environment and the laboratory. The natural clays exist in an alkaline environment (pH>7), but their exchange capacities 

were determined at neutrality (pH =7). Kelley 

(1957, p. 473) says that cations are adsorbed from 

chemically alkaline solutions in greater quantities 

than from neutral solutions; and, as the pH of a 

clay-water suspension is lowered in the laboratory, 

the excess cations adsorbed at higher pH tend to 

hydrolize off the clays. Supporting evidence for 

this hypothesis is given by Pratt (1961) and in the 

titration curves summarized by Grim (1953, p. 

130). 

The single exception to the apparent excess of exchangeable cations over exchange capacity is the sediment from 1,8.01 feet in the Huron core. The sample 

contained pyrite (about 1 percent) and bituminousappearing organic material (several percent). The pH 

of the hot-water leachate was 6.7, and the only anion 

determined in significant quantity was sulfate. Some 

of the exchange positions may have been occupied by 

hydrogen, which was not determined. 

EXCHANGEABLE CATIONS IN MODERN STREAM SEDIMENTS 

Calcium is by far the most abundant of the cations 

adsorbed by clays in the streams, although it is not the 

most abundant cation in solution in the stream waters. 

The cation composition of water samples from Little 

Panoche and Panoche Creeks and of sediments that were 

in approximate contact with these waters at the time 

they were sampled are given below. The cations conform to the generally recognized sequence of preferential adsorption at- low electrolyte concentrations, 

Ca>Mg>Na (Carroll, 1959, p. 749). 

Ca I Mg I Na I K Cation 

exchange 

Total ca~acity dissolved o clay- solids mineral 

(percent of total cation (ppm) assemblage equivalents) (meq/100g 

sample finer than 3p) 

Little Panoche Creek 

In solution __________ 35 24 39 2 432 ---------- Adsorbed by clays in 

creek bed _________ 71 29 0 0 -------- 68 

Panoche Creek 

In solution 1 _________ 32 29 38 1 1,310 ---------- Adsorbed by clays in 

creek bank ________ 84 16 0 0 -------- 116 

1 More details of this analysis given by Davis (1961, p. 27, sample collected Mar. 17, 

1958). 

EXCHANGEABLE CATIONS IN SUBSURFACE SEDIMENTS 

Several features of the distribution of cations in subsurface sediments are apparent in figure 15: a preponderance of calcium, a downward increase in adsorbed 

sodium, and, in all but the Oro Lorna core, a downward 

decrease in adsorbed magnesium. The increase in 

adsorbed sodium is probably related to the downward 

increase in the sodium content of the ground water in 

the sediments, as is shown by the following data summarized from Davis and Poland (1957, p. 450-462). 

Total disDepth interval solved solids 

(ppm) 

Surface to about 250ft_____________ 3, 000 

250 ft to top of Corcoran Clay Member________________________ 1, 500 

Bottom of Corcoran Clay Member 

to base of fresh water____________ 800 

N aCl-water zone (below bottoms of core holes)______________________ 14, 000? 

Sodium (percent of total cation 

equivalents) 

35 

55 

75 

Very high 

Although the percent sodium in the deeper fresh 

water averages about 75, the percent of adsorbed sodium 
C24 MECHANICS OF AQUIFER SYSTEMS 

never seems to exceed 35. The downward decrease in 

adsorbed magnesium is also related to a change in the 

cation composition of the ground water. Analyses 

given by Davis and Poland (1957, p. 454-455) show an 

average percent magnesium of 23 in the water above the 

Corcoran Clay Member and 6 in the water below the 

Corcoran. 

SEDIMENTS IN THE TULARE-WASCO AREA 

The sediments whose compaction accounts for the 

land subsidence observed in the Tulare-Wasco area inelude both marine and nonmarine deposits. They were 

derived from the Sierra Nevada, which borders the 

area on the east. The oldest of these sediments are 

probably upper Miocene; the youngest are Recent. The 

marine sediments have been assigned to the Santa 

Margarita Formation as used by Diepenbrock (1933) 

and an overlying upper Pliocene marine unit. l\{ost 

of the land subsidence observed to date has been due 

to compaction of the nonmarine sediments (B. E. 

Lofgren, oral commun., 1962). 

These sediments were studied in two cores. Locations 

of the core holes, both in southwestern Tulare County, 

are shown in figure 16. Other details of the coring are 

given in table 1. Note that the average core recovery 

was better in these sediments than it was in the sediments of the Los Banos-Kettleman City area or the 

Santa Clara Valley. 

Two other reports bear on the depositional history of 

the sediments of the Tulare-Wasco area. Klausing and 

Lohman ( 1964) describe the upper Pliocene marine unit, 

as cored in the Richgrove hole. B. E. Lofgren and 

R. L. Klausing, in a report on land subsidence in the 

Tulare-Wasco area, Calif. (in preparation as Prof. 

Paper 437-B), describe briefly the geologic units and 

structure. 

SOURCE OF SEDIMENTS 

The sediments represented by the Pixley and Richgrove cores have come chiefly, if not entirely, from the 

Sierra Nevada and its foothills. Lacustrine sediments 

in the Pixley core and marine sediments in the Richgrove core m·ay have received contributions from the 

non-Sierran drainage basins, but their sand and pebble 

constituents show little or no evidence of it. The silts, 

sands, and gravels are all arkosic, consisting mainly of 

quartz, feldspar, and fragments of granitic rock. The 

principal accessory constituents, which usually amount 

to 5-15 percent of the sediments, are biotite and green 

hornblende. These minerals reflect the assemblage of 

minerals in the granitic rocks of the Sierra Nevada. 

Minor constituents of the sediments are dark fragment~ 

of metamorphic rocks, mainly quartzite and slate plus 

a little serpentine, which probably were derived from 

the metamorphic terrane in the foothills of the Sierra. 

A little volcanic detritus was also deposited with the 

sediments. Glassy basalt, in pebbles and granules, was 

found in some of the coarser sands at depths between 

1,840 and 1,750 feet in the Richgrove area. Rhyolitic 

glass (index of refraction between 1.50 and 1.51), in 

silt-sized particles, was found at a depth of 1,058 feetpartly mixed with other detritus and partly concentrated (more than 90 percent glass) in a bedded deposit. 

I. E. Klein reported finding a thin layer of pumice at a 

depth of 540 feet in the Pixley core (B. E. Lofgren, 

written commun., 1964). Except for these minor occurrences, no other direct evidence of volcanic activity 

was found in the sediments. 

TYPES OF DEPOSITS 

The main distinction to be made in the sediments 

cored in the Tulare-Wasco area is between marine and 

nonmarine deposits. The evidence for the existence of 

both types of deposit is quite clear. The exact point 

of the transition from marine to nonmarine conditions 

is somewhat less so. The most detailed petrologic 

study was done on the Richgrove core 'because it contained both types of deposits. The Pixley core contains only nonmarine sediments. The distribution of 

deposits in the cores is shown in figure 17. The perti· 

nent evidence gleaned from the Richgrove core and the 

conclusions reached from it are given. in table 4. In· 

ferences about the origins of the nonmarine deposits 

are based on the criteria used in the Los Banos-Kettleman City area. 

MARINE DEPOSITS 

The marine deposits in the Richgrove core can be 

divided conveniently into two units-a well-sorted sand 

(below 1,900 ft) and a fine-grained siltstone (1,700 to 

about 760 ft)-with 200 feet of transitional sediment 

between them. The well-sorted sand has been correlated by subsurface mapping with the Santa Margarita 

Formation as used by Diepenbrock (1933) of Miocene 

age (Klausing and Lohman, 1964, p. D-14). On the 

basis of a study of diatom ·assemblages by Lohm·an, the 

siltstone unit has been assigned to the upper Pliocene 

and may be the equivalent of part of the San Joaquin 

Formation exposed on the west side of the San Joaquin 

Valley, and the siltstone-sand transitional sediments 

have been assigned tentatively to the Pliocene(~). 

The m·arine sediments probably were deposited in 

shallow water under mildly reducing conditions. The 

depth of water is suggested by the remains of shallowwater mollusks and Foraminifera that were found in 

the siltstone-sand transitional sediments. It is also suggested by some of the textural characteristics of the 
LiJ 

(.) 

c( 

LL. 

a:: 

:J 

(/) 

Cl 

z 

c( 

....J 

s: 

0 

....J 

LiJ 

IXl 

1-

LiJ 

LiJ 

LL. 

~ 

:i 

1-

a.. 

LiJ 

Cl 

PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C25 

0 

500 

1000 

0 50 100 

LITTLE PANOCHE 

~ 

CREEK 

ORO LOMA 

EXPLANATION 

IQ8a 

Calcium 

D 

Magnesium 

Sodium 

-

EXCHANGEABLE CATIONS 

(ADJUSTED PERCENT EQUIVALENTS) 

0 50 100 0 50 100 

0-

500-

STREAM SAMPLES 

PANOCHE 

CREEK 

CANTUA 

CREEK 

CORE-HOLE SAMPLES 

MENDOTA CANTUA CREEK 

0-

-

I I 

500-

I 

-

I 

1000 ~~~~:[]-· 1000-

1500-

-

1500-

-

2000-

-

0 

500 

1000 

1500 

2000 

0 50 

LOS GATOS 

CREEK 

100 

~I 

HURON 

FIGURE 15.-Cations adsorbed by clay minerals in principal streams and cores, Los Banos-Kettleman City area. 

Determined by H. C. Starkey. 

sediments. The good sorting of most of the sands in 

the 2,200- to 1,700-foot and 1,050- to 760-foot intervals, 

and the small-scale separation of sand and finer material 

in the siltstones in the 1,570- to 1,050-foot interval 

(described under "Other features" in table 4) suggest 

that a gentle winnowing process operated periodically 

during the deposition of these sediments. Reducing 

conditions are suggested by the good preservation of 

plant remains and by the ubiquitous presence of iron 

sulfides. 

The upper boundary of the marine siltstone unit is 

not so abrupt as indicated in table 4 or in figure 124.2 
C26 

T. 20 S. 

T. 23 S. 

T. 24 S. 

T. 26 S. 

T. 27 S. 

I 

I 

I 

I -------

1 

IO glu 

tl.lr:tl 

C!11~ 

..... z~~ ::;J 

~E-t 

____ l I __ _ 

I 

I 

I 

_j__ I 

I 

I 

I 

I 

----t----

1 

I 

I 

I 

I 

I 

I 

I 

I 

I 

-----+---- 1 

MECHANICS OF AQUIFER SYSTEMS 

I 

I I 

: I 

---r------------t---- 1 I 

I I 

I : 

I 

1 PIXLEY 

: (23/25-16N 1) 

Alpaugh 1 karlimart • I 1 

-------~-- -------r---- 1 I 

I I 

I I 

I I 

I I 

I 1 

I I 

I I 

I I 

ITULARE CO I 

- --T '--- -- ----r-'- --- I KERN CO I 

I I 

I I 

I I 

I 

I 

I 

I 

I 

-----+----------- 1 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I -----~-----------

2 0 2 4 6 MILES 

FIGURE 16.-Tulare-Wasco area showing locations of core holes. 

EXPLANATION 

Bedrock 

'\"""~~~~~ 

Edge of foothills 

@ 

Location of core hole 

of the paper by Klausing and Lohman (1964). Although the resistivity log (shown in fig. 22) shows an 

abrupt transition at a depth of 744 feet, visual examination of the sediments suggests a more gradual transition. In the 785- to 7 44-foot interval, interbedding of 

poorly sorted clayey silt with the massive siltstones suggests a gradual and fluctuating departure of the sea 

rather than a sudden and abrupt withdrawal 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA (JJ!1 

PIXLEY 

CORE 

SOURCE TYPE OF 

DEPOSIT 

AF 

Sierra 

Nevada 

AF 

0 

LA 

FP 

500 

FP 

EXPLANATION 

TYPE OF DEPOSIT 

AF, Alluvial fan 

FP. Flood plain 

LA, Lacustrine 

RICHGROVE 

CORE 

SOURCE TYPE OF 

DEPOSIT 

AF 

FP 

-=:::---

Sierra 

Nevada 

Shallow 

marine 

0 

w 

500 () 

<( 

LL 

0: 

:::;, 

rJ) 

c 

z 

<( 

...J 

1000 ~ 

0 

...J 

w 

Cl 

fw 

w 

LL 

1500 ~ 

:i 

f0.. 

w 

c 

2000 

FIGURE 17.--lSource and principal types of deposits represented by 

sediments cored in the Tulare-Wasco area. 

ALLUVIAL-FAN DEPOSIT'S 

Most of the nonmarine sediments in the two cores 

were deposited on alluvial fans. The uppermost 620 

feet of the Richgrove core and most of the Pixley core 

consist of alluvial-fan deposits, whose characteristics 

are given in table 2. The modern Tulare-Wasco area, 

like the Los Banos-Kettleman City area, is an area of 

alluvial-fan deposition. 

The alluvial-fan deposits in the Tulare-Wasco area 

differ from those in the Los Banos-Kettleman City area 

in two ways. First, they are coarser grained, reflecting 

the generally larger size of material supplied by the 

Sierra Nevada source area. They contain few fine clays 

such as are common in the alluvial-fan sediments in the 

Los Banos-Kettleman City area. And they do not contain clay aggregates of the type illustrated in figure 4. 

The second main difference is the evidence of more 

extensive soil-forming processes in the Tulare-Wasco 

area. Biotite has been intensely weathered: originally 

black flakes and books have gone partly or completely to 

fragile golden-yellow flakes. Soil textures (fig. 18)-

mainly cavities lined with carbonaceous material ' opaline material, or clay in oriented films (like those described and named "cutans" by Brewer, 1964, p. 205-

233)-suggest that organic and mineral material had 

been moved about within the sediments since they were 

232-511 0--00-----2 

FIGURE 18.-Photomicrographs of soil textures In alluvial sediment from depth of 232 feet in Richgrove core, Tulare-Wasco 

area. Long dimension of each photograph is about 1,000tt. 

Upper, Cavities (Cvl lined with clay. Layered clay (Cy) shows 

preferred orientation, presumably resulting from successive 

depositions on walls of caYity. Lowe•·, CaYitles (Cv) lined with 

clay and carbonaceous matter (black). Grain (Grl also surrounded by clay. 

deposited. The development of these features suggests 

that the alluvial-fan sediments in the Tulare-·Wasco 

area have accumulated more slowly than those across 

the San Joaquin Valley in the Los Banos-Kettleman 

City area. 

LACUSTRINE AND FLOOD•PLAIN DEPOSITS 

The lacustrine layer indicated in the Pixley core in 

figure 17 is the Corcoran Clay Member of the Tulare 

Formation, identified on the basis of its fine grain size 

and bluish-gray color and by subsurface correlation 

across the valley. The flood-plain deposits that lie below 

the alluvial-fan sediments in both cores were identified 

on the basis of criteria in table 4 and by their similarity 

to flood-plain deposits in the Los Banos-Kettleman City 

area. They may include some minor lacustrine deposits. 

PARTICLE SIZES 

The study of particle sizes in the Tulare-Wasco area 

is based largely on 157 samples from the two core holes. 
TABLE 4.-Eviderwe tor conditions ot deposition represented by sediments in Richgrove core, Tulare-Wasco area 

Depth below 

land surface Lithologic unit Particle-size characteristics Other features Organic remains Chemical indicators Inferred type of deposit 

(feet) 

-o 

- Some of silts and clays contain 

cavities, tubular or irregularly 

oblate, which are lined with Iron oxides, disseminated. 

- carbonaceous material, opaline 

material, or clay. AJ!uvial fan Calcite in hard nodules or soft irregular 

- Sediments loose to friable . Carbonaceous material in cav- accumulations; rarely cementing layers (on basis of oxidized color, 

ity linings or amorphous a few centimeters thick. poor sorting of particle 

Sand, silt, and clay Sand, silt, and clay mixed in vary- accumulations. sizes, and cavities) 

in beds 1- 10ft ing proportions; poorly sorted . Minerals, especially biotite, weathered. - thick. Yellow brown. 

No preferred orientation of clay500- mineral particles (mean orientation 

ratio 1.1). 

-

Preferred orientation of clay-mineral Iron sulfides associated with woody material. particles (one sample with orienta- Calcite as above. Flood plain - tion ratio of 1.5). Greenish to bluish gray. 

Woody material, in isolated Transitional 

- Siltstone, massive (virtually no visible well-preserved fragments Iron sulfides associated with woody material. 

Siltstone, fine to clayey, with a few bedding on small scale),hard (breaks as much as a few centimesand grains; well sorted . v.'ith conchoidal·or blocky fracture). ters long, or disseminated Greenish to bluish gray. Presumably shallow marine 

- Sand, loose. in small flecks. 

Sand, medium to fine, Preferred orientation of clay-mineral (on basis of lithologic well-sorted. particles (mean orientation ratio similarity to under1000- 1.6). lying sediments) 

- Most of siltstone finely laminated: siltstone layers a few centimeters thick 

Siltstone1 in beds alternate with layers or discontinuous 

- 20-100 ft thick, lenses, a few millimeters thick, of 

fine sand. Iron sulfides disseminated in small grains or intercalated with concentrated near organic material; occa- sand 2-15ft thick. Many sands contain oblate and rounded sionally replace diatoms; partly or com- - Siltstone, fine to clayey, with a few clasts of claystone as much as 2 cen- pletely oxidized to gypsum and iron oxide. 

timeters across. Marine diatoms. sand grains; well sorted. Gypsum in especially high concentrations 

- Sand, coarse to clayey, poorly sorted. Siltstone, hard; and loose sand. Woody material as above. in some siltstones below 1200 ft. 

Preferred orientation of clay-mineral 

particles (mean orientation ratio Greenish to bluish gray. 1500- 1.5). 

-

Siltstone, massive, hard. Shallow marine 

Sand, loose. Woody material as above. (mainly on basis of fossils) 

Siltstone 1 and Siltstone, fine to clayey, with a few Preferred orientation of clay-mineral Shallow-marine mollusks, 

sand in beds sand grains; well-sorted. particles (mean orientation ratio Fo-raminifera, fish 

- 2-20ft thick. 1.7). scales, crab(?) remains. Sand, coarse to medium, 

well·sorted. Woody material as above. 

Woody material in isolated 

2000- fragments as much as a 

Sand, massive. Sand, coarse to medium, Sand, loose. few centimeters long. Iron sulfides associated with woody material, well-sorted. partly oxidized to gypsum and iron oxide. 

- Shell fragments. 

t Claystone as logged from core inspection at drilling site and as listed by Klausing and Lohman (1964, fig. 124.2); particle-size analyses indicate siltstone. 

Depth below 

land surface 

(feet) 

0 ---

rrrrr- 500 

rrrrr- 1000 

rrrr- 1500 

rrrr-

-2000 

-

- ----

0 

&3 

~ 

Q 

~ Ul 

0 

":l 

> § 

~ t:J:l 

f!.l 

~ ~ Ul 
PETROLOGY, . SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C29 

The number of samples analyzed from and the estimated 

mean particle size of the three principal lithologic units 

are summarized in the following table. The mean sizes 

Estimated mean 

Lithologic unit Depth interval Number particle size (microns) 

sampled (feet) of 

samples Recovered Section as sediments a whole 

Nonmarine and 

transitional _________ 30- 785 121 20- 40 40- 80 

Marine siltstone and 

interbedded sands ___ 785-1,900 28 16- 30 8- 16 

Santa Margarita Formation as used by Diepenbrock (1933) _ 1,900-2,200 8 250-500 250-500 

of the sediments as a whole were estimated by comparing the mean sizes of the recovered sediments with 

the electrical-resistivity logs of the core holes. The difference between the mean size of the nonmarine sediments that were recovered ·and the size of the sediment 

particles in the nonmarine section as a whole is due to 

selective recovery, especially in the Pixley core. The 

difference in the marine siltstones and interbedded sands 

is due to selective sampling of the recovered core. Because the material was so uniform, the marine deposits 

were not sampled at close intervals. (See fig. 22 and 

table 8.) 

Selected percentiles, ·averages, and measures of sorting and skewness for each sample are given in table 8. 

The percentiles were interpolated by a digital computer 

from particle-size data provided by the Hydrologic 

Lruboratory. The digital computer also determined the 

modal particle size and calculated the measures of sorting ·and skewness, which are defined on pages 049 and 

C50. Particle-size-distribution curves for some individual samples a.re presented by Johnson, Moston, and 

Morris ( 1967). 

In order that the size characteristics of the nonmarine 

and marine deposits might be considered clearly and 

separately, the particle-size analyses of the transitional 

sediments (depths between 785 and 7 44 ft in the Richgrove core) have been left out of the discussions that 

concern figures 19--21, and 23. The transitional sediments are included, however, in fig. 22. 

PARTICLE ·SIZES OF NONMARINE SEDIMENTS 

Except for two samples from the lacustrine Corcoran 

Clay Member in the Pixley core, -all the samples of nonmarine sediments represent alluvial deposits. 

The triangular plots of the proportions of sand, silt, 

and clay (fig. 19B, 0) show that the nonmarine sediments are not so diverse in particle size as those cored in 

the Los Banos-Kettleman City area (compare with fig. 

5). The bulk of the points in figure 19B and 0 fall into 

the silty-sand and sand-silt-clay categories. The clay 

content ranges between 10 and 35 percent in most 

samples. Sixty-eight of the samples of nonmarine 

sediments (all from the Richgrove core) contain some 

gravel, but only 14 of these contain 5 percent or more 

of material coarser than 2,000p.. In general, then, the 

nonmarine sediments of the Tulare-Wasco area seem to 

be heterogeneous mixtures of sand, silt, and, to a lesser 

extent, clay. 

This impression is supported by the measures of 

average size, sorting, and skewness (fig. 20). Most of 

the median and modal diameters fall into a fairly narrow range of sizes, as compared to the wider general 

range in the Los Banos-Kettleman City area (fig. 6). 

The most abundant size range, judging from the concentration of modal diameters, is 31~-t to 62~-t. As in the 

Los Banos-Kettleman City are-a, the degree of sorting 

ranges mostly from fair to poor, and the skewness of 

the particle-size distributions reflects a disproportionately large amount of fine-grained material. 

The sediments in the Pixley area probably are not so 

fine grained on the whole as one might infer from the 

distribution of median diameters in the recovered sediments. Although the core recovery at Pixley was good 

(table 1), part of the section-200 of the uppermost 

260 feet-was not cored. According to the electric logs 

of the core hole (fig. 22), many of the coarsest sediments 

in the section are in the uppermost 260 feet. Most of 

these, therefore, were not sampled. 

The nonm·arine sediments in the Richgrove core, on 

the other hand, were cored and sampled on a fairly 

representa-tive basis. Although they do seem to 'be 

slightly coarser on the whole than sediments in the 

Pixley area, they are perhaps more representative than 

the sediments recovered at Pixley. 

PARTICLE SIZES OF MARINE SEDIMENTS 

In the unit of interbedded marine siltstone and sand 

that lies between depths of 785 and 1,900 feet in the 

Richgrove hole, the siltstones are in beds 20-100 feet 

thick, and the sands are mostly in layers 2-15 feet thick. 

The segregation into two types of sediments is not so 

well shown in figure 19D as it is in figure 21. The 

average diameters (median and mode) in this depth 

interval fall into two groups, one representing the siltstones and the other representing the sands. Because 

of selective sampling of the recovered core, however, the 

sands are overrepresented with regard to the siltstones. 

The highly skewed sediments-those with Skq,f/QDq, 

values larger than 0.4-represent bulk analyses of siltstones that contain thin laminae (a few millimeters 

thick) of fine sand. 
C30 

25 

SAND AND 25 

GRAVEL 

50 

PERCENT SILT 

A 

CLAY 

CLAY 

50 

D 

MECHANICS OF AQUIFER SYSTEMS 

75 

75 SILT 

EXPLANATION 

MICRONS 

Gravel 

Sand 

Silt 

Clay 

SAND AND 25 

GRAVEL 

SAND AND 25 

GRAVEL 

>2000 

62-2000 

4-62 

<4 

CLAY 

50 

c 

CLAY 

50 

E 

75 SILT 

75 SILT 

FIGURE 19.-Sand-silt-clay percentages of sediments cored in the Tulare-Wasco area. Based on data from the Hydrologic 

Laboratory of the U.S. Geological Survey, Denver, Colo. A, Nomenclature after Shepard (1954). B, Alluvial-fan sediments. 0, Flood-plain sediments, plus two lacustrine sediments (indicated by arrows). D, Marine siltstones and 

interbedded sands. E, Santa Margarita Formation as used by Diepenbrock (1933). 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C31 

~ 

UJ 

co 

::!! 

::::> 

z 

4 

4 

PIXLEY 

CORE 

RICHGROVE 

CORE 

ALL SAMPLES < 121 l 

62 1000 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

SAMPLES <93> WHOSE MODES 

COULD BE DETERMINED 

62 1000 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

4 62 1000 

MODAL DIAMETER, IN MICRONS 

SAMPLES <117> WHOSE QUARTILES 

COULD BE DETERMINED 

4 62 1000 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

]--.... L.L 

0 2 4 0 2 4 

QUARTILE DEVIATION (QDq) 

3]~~ -0.4 0 0.4 -0.4 0 0.4 

QUARTILE SKEWNESS(Skqcp ) 

QDcp 

FIGURE 20.-Measures of average size, sorting, and 

skewness in nonmarine sediments cored in the 

Tulare-Wasco area. 

(/) 

UJ 

...J 

a.. 

::!! 

<( 

(/) 

IJ.. 

0 

~ 

UJ 

co 

::!! 

::::> 

z 

MARINE 

SILTSTONES 

AND SANDS 

SANTA 

MARGARITA 

FORMATION 

ALL SAMPLES <36) 

4 62 1000 62 1000 

MEDIAN DIAMETER, IN MICRONS 

SAMPLES <32> WHOSE MODES 

COULD BE DETERMINED 

4 62 1000 

MEDIAN DIAMETER, 

IN MICRONS 

4 62 1000 62 1000 

MODAL DIAMETER, IN MICRONS 

SAMPLES <35> WHOSE QUARTILES 

COULD BE DETERMINED 

4 62 1000 

MEDIAN DIAMETER, 

IN MICRONS 

jJ.. L 

0 2 0 2 

QUARTILE DEVIATION (QDcp) 

10 

0 

0 0.4 -0.4 

1~.~~~ 0 0.4 

QUARTILE SKEWNESS(~~: ) 

FIGURE 21.-Measures of average size, sorting, and 

skewness in marine sediments from the Richgrove 

core, Tulare-Wasco area. 

The Santa Margarita Formation as used by Diepenbrock ( 1933), sampled at depths between 1,900 and 2,200 

feet, is mainly a well-sorted sand. The eight samples 

whose characteristics are plotted in figures 19E and 21 

seem to be representative of the cored intervals. 

SPATIAL D-ISTRIBUTION OF PARTICLE SIZES 

Figure 22 shows the variation in particle size with 

depth in the two cores and serves as a spatial summary 
C32 MECHANICS OF AQUIFER SYSTEMS 

PIXLEY 

CORE 

MEDIAN DIAMETER, 

IN MICRONS 

8 62 500 

• 

• 

• 

• 

• 

•• • 

• •• • 

• I • 

, 

••• • •• • il' 

• • • 

•• • 

EXPLANATION 

TYPE OF DEPOSIT 

AF, Alluvial fan 

FP, Flood plain 

LA, Lacustrine 

0 

AF 

LA 

FP 

AF 500 

p 

1 

RICHGROVE 

CORE 

MEDIAN DIAMETER. 

IN MICRONS 

8 62 500 4000 

• 

•• .. • •• . , . \-· . . \ . ,., : .. ~· ~ 

• •• .;: 

. ·= .: 

,, 

... i 

•• •• . .. -

• 

• • • 

• 

• 

• • 

• 

• 

• 

• 

• 

• 

• 

• 

• 

•• 

• 

• • • • • 

• • 

• 

• 

• 

• 

• 

•• 

• 

• 

500 

1000 

1500 

2000 

~-----L-------------·------~----~2200 

LLJ 

(.) 

<( 

u. 

a::: 

:::::> 

(J) 

0 

z 

<( 

..J 

s: 

0 

..J 

LLJ 

CD 

1-

LLJ 

LLJ 

u. 

z 

:i 

t 

LLJ 

0 

FIGURE 22.-Variations in particle size with depth, Tulare-Wasco area. Resistivity log is left column of each composite; 

range, from left to right, is 0-40 ohms m2/m. 

of some of the foregoing descriptions of size. As in 

figure 7, median diameter and resistivity indicate particle size. The types of deposits are also included. 

The preponderance of silt in the section between 1,900 

and 7 44 feet in the Richgrove core is better shown in 

the resistivity log than in the distribution of median 

diameters; selective sampling for size analysis of this 

section gave excessive emphasis to the interlayered 

sands. Based on the trend of median diameters, the 

nonmarine sediments of the Richgrove core seem to 

coarsen progressively between about 750 feet and the 

land surface, but no clear systematic variation appears 

in the Pixley core. 

INTERRELATIONS OF PARTICLE-SIZE MEASURES 

Figure 23 shmvs graphs of median diameter against 

the coarsest percentile (C), sorting, and skewness for 

the ·alluvial-fan and shallow-marine deposits of the 

Tulare-Wasco area. Not included in the graphs are 

samples that are cemented or that contain interlaminations, or whose conspicuous soil textures indicate that 

material has been moved around since the sediment was 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C33 

2 

64,000 

IJ..i 16,000 

..J 

i=CI) 

zz 4000 

LLIQ 

Uo::: 

o:::u 1000 LLI- O..:::i! 

1-z Cl)_ 250 0::: 

iL: 62 

16 

--.. 4 

~-&-

1.1.10' 3 ..J'- Ii=z 

o:::o 2 <C- :>I0~ > LLI 

0 

0 

:} 0.6 

0' 

....... 0.4 -e. 

~~ i='- 0.2 

<CCI) ..JCI) 

LLILLI 0 o:::z 

~ LLI -0.2 ~ Cl) 

-0.4 

1.2 

-:e. Qo 0.8 

LLI~ 1-'- 0.4 :>(I) 

..JCI) 

OLLI 

Cl)z 0 a:l~ <CLLI 

~ -0.4 Cl) 

-0.8 

4 

ALLUVIAL 

FAN 

8 31 125 500 2000 2 

I I I I I -

• 

""• • -

~- .,. . • ··\] ..c ... - ••I -• ~ • . 1 • · ... I I I 

• 

• • 

···~·· • • • • ....... . .. • • • 

• • • • • • • • • • • 

.. ·...,~· ..... . .. .. • • 

• 

16 62 250 1000 

SHALLOW 

MARINE 

8 31 125 500 2000 

• • • ·- • ~· • • • •• • • 

4 16 62 250 1000 

MEDIAN DIAMETER,IN MICRONS 

FIGURE 23.-Median diameter against coarsest percentile, sorting, 

and skewness in alluvial-fan and shallow-marine sediments, TulareWasco area. 

deposited. Flood-plain and lacustrine deposits are not 

included because too few samples of homogeneous material are available. The measures of sorting (QD"') 

and skewness (Skq"'jQD"' and Skq"') are defined on 

page C49. The reasons for attempting to graph these 

measures against median diameter were reviewed on 

page 013-016. 

ALLUVIAL-FAN SEDIMENTS 

The relations between the particle-size measures in the 

alluvial-fan sediments of the Tulare-Wasco area (left 

col., fig. 23) seem to be fairly random. They are of 

little use in deciphering the depositional history of the 

sediments, unless one accepts the assumption that a lack 

of clearly visible relati9ns signifies a lack of discrimination between particle sizes on the part of the transporting and depositing medium. 

The only suggestion of discrimination is in the OM 

pattern (upper row, left col., fig. 23), a wide band of 

points roughly parallel to the C = M d line. This pattern is similar to the pattern for recent mudflow deposits given by Bull (fig. 11) . The CM pattern in the 

upper left corner of figure 23, however, actually consists of two patterns, one from each core of alluvial-fan 

sediments taken in the Tulare-Wasco area. All the 

samples from the Pixley core have C values less than 

2,000p.; all but two samples of alluvial-fan sediments 

from the Richgrove core have C values greater than 

l,OOOp.. As the principal linear trends of points in the 

two constituent OM patterns lie at angles of 20°-30° 

to the overall trend suggested in figure 23, the overall 

pattern is probably not significant. 

SHALLOW-MARINE SEDIMENTS 

Particle-size measures for 20 shallow-marine sediments from the Richgrove core are graphed in the right 

column of figure 23. All the marine sediments that 

have median diameters of 250p. or more are from the 

well-sorted sand unit (Santa Margarita Formation as 

used by Diepenbrock, 1933); most of the finer marine 

sediments are from the units of interbedded siltstone 

and sand . 

Although the samples are from two different stratigraphic units and are too few to define the relations with 

much certainty, there seem to be several regular relations between the particle-size measures. If the OM 

pattern a.ctually is as enclosed by the dashed line (upper 

right cor., fig. 23), it is, of all the sediments treated in 

this report, the closest replica of Passega's ideal tractive 

pattern (compare with fig. 9). It implies a high degree 

of discrimination, on the part of the transporting and 

depositing medium, between particles of different sizes. 

The distinction between well-sorted sands and less well 

sorted finer sediments (second row, right col., fig. 23) 

is approximately the same as in the alluvial sediments 

of the Los Banos-Kettleman City area and the Santa 

Clara Valley. The relation between median diameter 
C34 MECHANICS OF AQUIFER SYSTEMS 

and skewness-especially the absolute skewness (lower 

right cor., fig. 23)-may be sinusoidal, as suggested by 

the dashed lines in the figure. This suggestion is supported by the pattern of decreasing skewness with decreasing size in the fine-grained alluvial-fan sediments 

of the Los Banos-Kettleman City area (fig. 12) and by 

a similar sinusoidal pattern observed in river sediments 

by Folk ap.d Ward (1957, p. 19). 

CLAY MINERALS AND ASSOCIATED IONS 

CLA. Y MINERALS AND THEIR ASSEMBLAGES 

As in the Los Banos-Kettleman City area, the principal cia y mineral in the upper Cenozoic sediments of 

the Tulare-Wasco area is montmorillonite. Subsidiary 

clay minerals are illite, ·a kaolinite-type mineral, and 

vermiculite. Also present in minor amounts are chlorite 

and a low-grade illite-montmorillonite mixture. The 

distribution of clay minerals in the two cores from this 

area is shown in figure 24. The criteria for the identification of the clay minerals and the method of estimating their relative proportions are given on pages 

C67-C71. Detailed results of the clay-mineral analyses of 26 sa.mples are given in table 13. Assuming that 

these samples are representa.tive, the average claymineral composition of the upper Cenozoic sediments of 

the area is approximately as follows: 

Clay minerals 

Montmorillonite ____________________ _ 

Illite __________ - _________ ----------- Kaolinite-type mineral _______________ _ Vermiculite ________________________ _ Chlorite ___________________________ _ 

Mixed-layer illite-montmorillonite _____ _ 

In nonmarine I sediments t 

In marine 

siltstones 

Nearest 5 percent 

60 

20 

10 

10 

0 

Trace 

80 

5 

5 

0 

5 

Trace 

1 1ncludes ~II sediments at depths of less than 760 ft, figure 22. The boundary between marme and nonmarine sediments in the Richgrove core is actually transitional between 785 and 744ft. 

Two, and perhaps three, clay-mineral assemblages are 

present in the upper Cenozoic sediments of the area. 

The differences between the assemblages are not so much 

in the minerals themselves as in the relative proportions 

of the same group of clay minerals. The assemblage in 

the fine-grained siltstone layers of the marine deposits, 

as given above, consists of a large proportion of montmorilloni,te and minor amounts of illite, a kaolinitetype mineral, and chlorite. In the nonmarine sediments 

a slightly different assemblage was found in each of the 

two cores. Montmorillonite is the principal mineral in 

both assemblages, amounting to 50-70 percent. In the 

Pixley core the subsidiary minerals are, in decreasing 

order of abundance: a kaolinite-type mineral, vermiculite, and illite. The subsidiary minerals in the upper 

LIJ 

(.) 

c( 

LL. 

0:: 

:::::1 

f/) 

0 

z 

::s 

:: 

0 

..J 

LIJ 

CD 

t;:; 

LIJ 

LL. 

~ 

::c 

1-

a.. 

LIJ 

0 

CLAY MINERALS 

(ESTIMATED PARTS PER TEN} 

0 

500 

0 5 

PIXLEY 

CORE 

EXPLANATION 

Montmori 

-

lion ite 

D 

Illite 

-

10 

IIIII 

Kaolinite-type mineral 

Chlorite and kaolinite-type 

mineral (undifferentiated} 

0 

.. 

1000 

5 

RICHGROVE 

CORE 

10 

-IIIII 

-IIIII 

-1111 

-1111\ 

-IIIII 

-IIIIi 

-IIIII 

-

IIIII 

1500····-[!Ill 

2000 

FIGURE 24.-Clay minerals in cored sediments, Tulare-Wasco 

area. Trace amounts not illustrated. Vermiculite in 

Pixley core included with montmorillonite. 

760 feet of the Richgrove core, listed in the same order, 

are illite and a kaolinite-type mineral; vermiculite was 

not detected. 

SOURCES OF C'LA Y MINERALS 

The problem of the origin of montmorillonite in sediments from the Sierra Nevada was treated in the section, 

"Sources of montmorillonite" (p. C21-C22) and needs 

no ful'lther discussion here. 

The kaolinite-type mineral in the sediments of the 

Tulare-Wasco area may well be true kaolinite or a member of the kaolinite group, derived from the weathering 

of granitic rocks in the Sierra Nevada. R. J. Janda 

(written commun., 1964, 1965) reports that kaolinite 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C35 

and halloysite are predominant clay-mineral constituents of the soils and alluvium in the upper San Joaquin 

basin in the Sierra. 

Illite and vermiculite are probably derived from biotite, which is a conspicuous constituent (averaging 

about 5 percent) of the coarser sediments. The illite 

probably represents finely divided biotite. The vermiculite probably represents biotite that has been altered 

chemically during weathering. (See Barshad, 1948.) 

TOTAL CLAY-MINERAL CONTENT OF SEDIMENTS 

The total clay-mineral content of the sediments underlying the Tulare-Wasco area is estimated to be as 

follows: 

Lithologic unit 

PercentClay minerals Montmorillonite and 

vermiculite 

-----------------------------1-------

Nonmarine sediments ________________ _ Marine siltstones and sands __________ _ 

Santa Margarita Formation as used 

by Diepenbrock (1933) ____________ _ 

15 

25 

<2 

10 

20 

<2 

These estimates were made on the same basis as the estimate of the clay-mineral and montmorillonite content 

of the sediments of the Los Banos-Kettleman City area: 

by averaging the percents finer than 3p. determined in 

the cored sediments (taken from the cumulative curves 

drawn in the Hydrologic Laboratory) and adjusting the 

average to allow for the effects of selective core recovery. 

IONS ASSOCIATED WITH CLAY MINERALS 

The principal ions adsorbed by the clays of the 

Tulare-Wasco area are calcium, magnesium, sodium, 

·and hydrogen. The principal anions associated with 

the fine-grained sediments are sulfate and bicarbonate 

plus a little chloride. Results of the analyses for these 

ions are given in table 13. 

DISTRIBUTION OF EXCHANGEABLE CATIONS 

The exchangeable cations adsorbed by the clay 

minerals in the Pixley and Richgrove cores are represented in figure 25. As before, the illustrated percentages were adjusted by subtracting the equivalent of 

total anions from the total calcium ions-or, where 

insufficient ealcium was available, from the total calcium 

and magnesium ions. As in the clays of the Los BanosKettleman City area, the adjusted sum of the exchangeable cations in most of the sediment's exceeds the determined ca.tion-exchange capacity. 

In seven of the sam pies from the Richgrove core, 

however, including four of those that are shown to 

contain exchangeable hydrogen, the adjusted sum of the 

0 

500 

1.1.1 

(.) 

<( 

1..1.. 

0:: 

:::1 

en 

0 

z 

<( 

_J 

~ 

0 

_J 

1.1.1 

m 

1-

1.1.1 

1.1.1 

1..1.. 

~ 

:i 

1-

a. 

1.1.1 

0 

0 

EXCHANGEABLE CATIONS 

(ADJUSTED PERCENT EQUIVALENTS) 

50 100 0 50 100 

PIXLEY 

CORE 

RICHGROVE 

CORE 

0 -

I 

x'>:. ,'\c'\J I 

• 

I 

I 

500 I 

I 

I 

• 

• 

1000 

-

-

EXPLANATION 

- ~ 

Calcium 

D 1500 

-

Magnesium 

§ 

Hydrogen 

-

Sodium 

-

ms<X1 

2000 -

FIGURE 25.-Cations adsorbed by clay minerals in cored 

sediments, Tulare-Wasco area. Determined by H. C. 

Starkey. 

cations is less than the determined exchange capacity 

(table 13). This difference may be due to one or more 

of the following causes. 

1. The sum of the cations may have been overadjusted 

for the soluble anions; that is, some of the soluble 

anions (mainly sulfate) may not have been combined with calcium, but may have been in solution 

or adsorbed by the clay minerals. The work of 

Chao and others (1962) suggests that the sulfate 

adsorbed by clays is easily removed by leaching 

with water. 

2. Some of the exchange sites may have been occupied 

by aluminum, which was not determined in the 

analyses. Aluminum may constitute a consider-
C36 MECHANICS OF AQUIFER SYSTEMS 

able part of the exchangeable cations in acid 

sediments (Wiklander, 1955, p. 110). 

3. The disparity may be related to differences in pH 

between the natural environment and the laboratory. The cation-exchange capacities were determined at neutrality, whereas four of these sediments registered significantly acid pH values (fig. 

27). Evidence collected by Pratt ( 1961) suggests 

that the cation-exchange capacity at low pH may 

be less than the exchange capacity of the same material at neutral pH. 

The exchangeable-cation assemblage in the alluvial 

sediments at depths of less than 760 feet is dominated by 

calcium. Magnesium is subsidiary; exchangeable sodium is present in about half the samples. The clays 

in this depth interval are probably in near equilibrium 

with waters being pumped from the coarser grained 

sediments in the same interval-waters in the 120- to 

770-foot interval in the Pixley area and in the 180- to 

680-foot interval in the Richgrove area, as tabulated 

below. 

Area 

Total dis- Sodium 

Depth interval solved (percent of 

(feet) solids total cation 

(ppm) equivalents) 

----------·----------------

Pixley_____________________ 120- 770 

Richgrove_________________ 180- 680 

500-1,600 

1,400-2,200 

200 

300 

300 

400 

70 

50 

85 

90 

These data were summ'arized from analyses (Hilton 

and others, 1960, p. 465, 475-479, 491) of water from 

wells whose perforated depths were known: 5 wells in 

the same township as the Pixley core hole and 16 wells 

within 5 miles of the Richgrove core hole. 

The assemblage of exchangeable cations in the marine 

siltstones, as sampled at depths between 760 and 1,900 

feet in the Richgrove core, is marked by a downward 

increase in sodium and a corresponding decrease in calcium. This may be related to any or all of the following factors. 

1. The proportion of sodium relative to the other 

cations, in the water being pumped from these sediments, increases downward-see the table in the 

previous paragraph. The water, however, is being 

produced mainly from the sands, whereas the exchangeable cations were measured in the clayey 

siltstones, and the two types of sediments may not 

be in chemical equilibrium. Lack of equilibrium 

is suggested by the large concentrations of salts in 

the clays as compared to low concentrations of 

solids in the water being pumped from the sands 

and by the preponderance of sulfate over bicarbonate in the clays as compared to the reverse relation 

in the waters in the sands (discussed in more detail 

under "Sulfate in the marine siltstones"). 

2. The concentration of salts in the clays increases 

downward (fig. 27). The ratio of monovalent to 

divalent cations adsorbed by clay minerals is a 

direct function of the concentration of ions in the 

sediment-water mixture (Wiklander, 1955, p.128). 

The data plotted in figure 26A suggest a definite 

relation between salt concentration ·and the proportion of adsorbed sodium. 

3. The pH also is lower at lower depths (fig. 27). 

Work by Pratt and others ( 1962) shows that the 

ratio of adsorbed sodium to adsorbed calcium may 

vary directly with acidity-that is, inversely with 

pH. The data plotted in figure 26B suggest a defi300 I T - • 

en' 

oz • 

:JO 

0 :J 200 - -

en: 

o::;; 

LLJ • >0::: 

...JLIJ 

oo.. 

en en ~I- oa::: 

...J ~ 100 1- • - <( • 1-z 0- • 1- • • 

• • • 

A 

0 I I 

0.1 0.5 1.0 

I I T 

• • • • 

• • 

8 i- -

• 1- -

I 

Q. 6 1- -

• 1- -

• 

4 r-B • • ·- I I I 

0.1 0.5 1.0 

ADSORBED 

Na 

Ca+Mg 

FIGURE 26.-Relation of the proportion of adsorbed 

sodium to salt concentration (..4.) and pH (B) 

in sediments below 760 feet in the Richgrov~ 

core, Tulare-Wasco area. Adsorbed cations determined by H. C. Starkey, who also determined 

the pH in 10 : 1 water-sediment mixtures. Total 

dissolved solids (dissolved from 10 g sediment in 

500 ml hot water) measured by Claude Hull'man 

and A. J. Bartel. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C37 

nite SULFATE IN THE MARINE SILTSTONES relation between pH and the proportion of 

adsorbed sodium. 

On the basis of the evidence presented, I suspect that 

the variations in the proportions of adsorbed sodium 

are related in a complex way to both the acidity and 

the concentration of soluble salts. 

The soluble-anion analyses (table 13) show substantial amounts of sulfate in the marine siltstones. Visual 

examination of these sediments shows that they contain 

gypsum in irre.gular accumulations, often associated 

with organic material or partly oxidized iron sulfides. 

0 

LIJ 500 

() 

<( 

u. 

a:: 

::J 

C/) 

Q 

z 

<( 

...J 

s: 

g 1000 LIJ 

ca 

1-

LIJ 

LIJ 

u. 

z 

:i 

1-

a.. 

LIJ 

Q 1500 

2000 

TOTAL DISSOLVED 

SOLIDS, IN PARTS 

PER MILLION 

0 200 

• 

• • 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

0 

500 

1000 

1500 

2000 

SOLUBLE ANIONS, 

IN PERCENT 

EQUIVALENTS 

0 100 I I 

-

-

• 

• 

• 

-

• - -

EXPLANATION 

D 

Sulfate 

Bicarbonate 

-

~ 

Chloride 

0 

500 

1000 

1500 

2000 

pH 

4 6 8 10 

• 

• • 

• 

• 

• • 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

FIGURE 27.-Soluble salts, soluble anions, and pH of fine-grained sediments from the Richgrove core, Tulare-Wasco area. 

Total dissolved solids and soluble anions measured (by Claude Huffman and A. J. Bartel) in hot-water leach: 500 ml 

hot water to 10 g sediment. pH measured by H. C. Starkey in 10: 1 water-sediment mixture. 
C38 MECHANICS OF AQUIFER SYSTEMS 

When samples of the sediments were allowed to dry, 

clean surfaces became crusted with gypsum · (selenite) 

crystals, indicating that the interstitial water of the 

sediments contained sulfate in significant amounts. 

The distribution of sulfate with regard to the other 

anions, salt concentration, and pH, is shown in figure 

27. The data plotted in the figure suggest that the large 

concentrations of soluble salts are mainly suHaites, and 

that the low pH values recorded in the sediments are 

related to high concentrations of sulfate. 

The origin of the sulfate is not clear from a study of 

the chemical data. The equivalent ratio of sulfate to 

bicarbonate, as large as 30 in some of the fine-grained 

sediments, is much ·greater than that in the water being 

pumped from the interbedded sands ( 0.5 or less, according to analyses reported by Hilton and others, 1960, 

p. 475-479, 491). The total solids leached from the 

clayey sediments suggest that the concentration of 

electrolyte in their interstitial waters may have been 

as great as 20,000 or even 30,000 ppm (parts per million) ; in contrast, only 300-400 ppm are dissolved in the 

pore water of the sands. The interstitial water of the 

clayey sediments cannot represent trapped sea water, as 

the soluble anions include virtually no chloride. 

On the hasis of petrographic evidence, however, one 

can suggest (and I thank D. E. White, of the Geological 

Survey, for this suggestion) that the sulfate has been 

formed by the oxid81tion of iron sulfides within the sediments since they were buried. Iron sulfides are present 

in nearly all the fine-grained sediments at depths below 

620 feet in the Richgrove core: in some pl·aces, intimately associated with carbonaceous organic material 

or replacing diatom skeletons, and in other places, disseminated through the sediment with no apparent local 

relation to organic material. Much of the iron sulfide 

is partly oxidized, as shown by an iridescent tarnish on 

the grain surfaces and by reddish-brown staining of 

the adjoining sediment. Gypsum is also associated 

with the partly oxidized sulfide. In some sediments, 

one can see fragments of ca~bonaceous material that are 

surrounded by partly oxidized iron sulfide which, in 

turn, is surrounded by a band of gypsum-rich sediment. 

Apparently, the sulfides were formed in the presence of 

organic material shortly after the sediments were 

deposited. Subsequently, they were oxidized, forming 

sulfate ions in the pore solutions tha·t reooted with calcium to form gypsum. The absence of chloride in the 

sediments im·plies that the original interstitial water 

(buried sea water) was removed from the sediment after 

the formation of the sulfides and before_, their subsequent oxidation. 

SEDIMENTS IN THE SANTA CLARA VALLEY 

Most of the sediments whose compaction causes the 

land subsidence in the Santa Clara V alley-1that is, sed.imenlts to a depth of about 1,000 feet-were deposited by 

alluvial processes. They were eroded from the Santa 

Cruz and Di81blo Ranges that border the valley to the 

southeast and northwest. The oldest deposits probably 

are late Pliocene; the youngest, Recent. 

Most of this study is based on sediments from the two 

core holes whose loca-tions are shown in figure 28. Both 

of these holes are in Santa Clara County. The San Jose 

core hole is on the bank of Coyote Creek, in the 12th 

Street Yard of the San Jose Water Co. The Sunnyvale core hole is in a highway interchange near the 

southeast corner of Moffett Field Naval Air Station. 

Details of the core recovery are given in table 1. Note 

the small amount of sediment recovered in the San Jose 

core, a reflection of the large amount of gravel (which 

could not be recovered by the rotary coring apparatus 

that was used) in the sediments that lie beneath the coring site. 

Polund and Green ( 1962) have described some of the 

results of land-subsidence studies in the Santa Clara 

Valley. A more extensive report on the aquifer system 

and its compaction in the Santa Clara Valley is being 

prepared by J. H. Green as Professional Paper 437-F. 

SOURCE OF SEDIMENTS 

The Franciscan and Knoxville Formati~n of middle to late Mesozoic age constitute the principal 

source terrane of the sediments in the cores. Thet.oe 

formations consist of sandstones (mostly graywackes), 

shales, cherts, and mafic and ultramafic rocks (mostly 

serpentine). They crop out in most of the areas of the 

Diablo and Santa Cruz Ranges that are drained by the 

two principal streams in the Santa Clara Valley, Coyote 

Creek, and Guadalupe River. 

Sands in the Sunnyvale and San Jose cores are 

characteristically lithic, medium dark ( 30-60 percent 

dark grains), and nonmicaceous. Most of the sandand gravel-sized rock fragments a.re serpentine (which 

amounts to 10 percent of some sediments, dark-red 

chert, porphyritic mafic rock (basalt and diabase~) with 

oxidized iron -stained groundmass, lithic sandstone, and 

shale. Among the easily recognizable accessory minerals are gl·aucophane and oxyhornblende. Micaceous 

minerals, usually biotite that appears to be altered, are 

rare and never amount to more than 1 percent of a 

sediment. 

TYPES OF DEPOSITS 

The deposits represented by the cored sediments are 

nonmarine, mostly alluvial, with possibly a few lacustrine deposits at depths below 700 feet. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C39 

122°15' 

37°30' 

Menlo 

·p~~--· .·• / Palo Alto 

121°45' 

EXPLANATION 

® 

Core-hole location 

//////// 

Boundary of Santa Clara Valley as 

denoted by boundary between 

alluvial deposits and consolidated 

rocks 

Alviso I 

SUNNYVALE ) 

(6S/2W-24C7) ~ ·--~ Mountain [ ® ~~~ \% • Agnew ·to . View : 

. \ . ~~ -~ •Sunnyvale .. 0 

~~~Alum Rock . . 

37°15' 

0 2 3 4 5 MILES 

( 

) 

Santa 

Clara 

• 

Campbell• 

( 

~ l -~ 

SanJos~~. 

FIGURE 28.--8anta Clua Valley showing location of core holes. 

MODERN ALLUVIAL SEDIMENTS AND SOILS 

The alluvial sediments in the cores are perhaps best 

understood when they are compared with the sediments 

and soils exposed at the present-day land surface in the 

Santa Clara Valley. To illustrate the range of the conditions and materials that are present, two extreme 

types will be discussed. 

Exposed near the major streams (Coyote Creek at 

the San Jose coring site, for example) are channel or 

overbank deposits. These are sandy, sometimes gravelly, sediments. Their yellow-brown color reflects the 

free iron oxide that coats or stains their constituent 

particles. Little soil has developed on the alluvial deposits found at low terrace and flood-plain levels along 

the streams (the Mocho soil series of Gardner and 

others, 1958, p. 95). On higher terrace levels above the 

streams, however, some soil has developed as shown by 

the segregation of calcium carbonate into layers or into 

accumulations along tubular openings, such as root 

holes, in the soil (the Sorrento soil series of Gardner 

and others, 1958, p. 119-120}. 

In the low-lying areas away from the major streams 

(as in the vicinity of the Sunnyvale core hole) quite 

another type of ma-terial is prevalent. This is a clayrich black to da.rk gra.y highly calcareous soil (the 

Castro and Sunnyvale soil series of Gardner and others, 

1958, p. 69-70, 123) formed on fine-gra.ined alluvial sediments that were deposited a.t the edges of alluvial fans 
C40 MECHANICS OF AQUIFER SYSTEMS 

or flood plains. The deposition of this sediment must 

have been mainly subaerial. The modern soils on this 

type of sediment are poorly drained because they are 

on nearly level ground, they have very low permeabilities, and the water table is close to the surface (less than 

20 ft at the Sunnyvale coring site in 1960) . They are 

full of organic material ·and calcite-the calcite in nodules or large irregular blotches. When dry, the soils 

break into blocks along suborthogonal fractures. Before they were cultivated by man, these soils supported 

only grasses. 

OLDER ALLUVIAL SEDIMENTS AND SOILS 

Many of the older deposits in the cores are similar to 

the modern types found near the coring sites-the channel and overbank deposits being common in the San Jose 

core and the dark calcareous soils predominating in the 

Sunnyvale core. In the upper 500 feet of the cores, 

these two types, plus an intermediate-type materiaL are 

present almost to the exclusion of all other types. The 

intermediate-type material-a poorly sorted sand-siltclay mixture, characteristically olive brown or blotchy 

(yellow-brown blotches in a dark-gray mass or vice 

versa)-is found in both cores~ 

Another type of fine-grained deposit was noted in 

sporadic occurrences in the upper part of the San ,Jose 

core. It is dark gray and has some of the characteristics given in table 3 for fine materials deposited in 

standing water-fine laminae and well-developed preferred orientation of clay-min~ral particles. Ponds or 

depressions apparently existed on the flood plain or fan 

near Coyote Creek, and fine-grained material was deposited slowly in them. 

Two other distinct types of sediments were found at 

depths below 500 feet in both cores: fossiliferous silts 

and rhythmically interlaminated silt and clay. Fossiliferous silts were found at depths near 760, 870, 900, 

920, and 940 feet in the Sunnyvale core, and 830 feet in 

the San Jose core, in beds that ranged in thickness from 

3 to 9 feet. The silts from the Sunnyvale core contain 

an assemblage of fresh-wa.ter mollusks identified by 

D. W. Taylor (report on referred fossils, 1962) as belonging to the genera Pisidium, Fl!uminieola, Lym,naea, 

Gyraulus, M enetus, and H elisoma. The silt from the 

San Jose core contains only fresh-water snails belonging 

to :the genera Lymnaea and Gyra.ulus (Taylor, report on 

referred fossils, 1963). All but one of these forms 

(Fluminicola yatesia.na Cooper) is -still living. They 

inhabit lakes or perennial streams. 

The interlaminated silt and clay-clayey silt in layers 

a few centimeters thick and silty clay in layers a few 

millimeters thick-is chara-cteristically d:ark yellow 

brown or olive brown. The layers usually make up beds 

a few feelt thick, interbedded with fossiliferous silts, 

coarser sands or gravels (in the San Jose core), or with 

dark-gray calcareous dayey silits (in the Sunnyvale 

core). The layers occasionally contain some calcite, but 

are often noncalcareous; they contain no cracks or other 

soillike structures. The clay particles have some preferred orientation parallel to the bedding-slight in the 

silt layers and better developed in the clay layers-the 

degree of orientation being less than that in the 

lacustrine Corcoran Clay Member in the Los BanosKettleman City area. Except for their color, these 

sediments have characteristics similar to those of the 

flood-plain deposits- described from the Los BanosKettleman City area. The presence of these sediments, 

along with the fossiliferous silts, suggest that conditions 

were generally wetter when they were being deposited 

than conditions in the Santa Clara Valley today. 

The spatial distribution of these types is not well 

enough known to be conveniently summarized i.n some 

such form as figures 3 and 17 or table 4. The different 

types are closely interbedded and are not uniform for 

large thicknesses. They are not continuous enough to 

be traced laterally by drillers' logs or by the few available electric logs. The recovery of the San Jose core 

was too poor ( 173 ft of the total 1,000-ft interval) for 

an accurate description of the sediments that it represents. One feature, however, is obvious : the main sense 

of the spatial variation is in the horizontal directionfrom one part of the valley to another-in contrast to 

the mainly vertical sense of the variation in the TulareWasco area. 

ABSENCE OF ESTUARINE DEPOSITS 

Although both core sites were near San Francisco 

Bay (the Sunnyvale site is only 3 miles from the bay 

and was 35 ft above mean sea level in 1961), neither 

core contains sediments that could be recognized as estuarine. In addition to the strong resemblance between 

the cored sediments and the modern alluvial deposits 

exposed at the land surface, the absence of estuarine 

sediments in the cores is suggested by the following 

lines of evidence. 

1.1 No marine or estuarine fossils were found in the sediments. The only fossils recognized were plant 

debris and the fresh-water snails and claJU~ li~ed 

above. . .. " 

2. The salts in the core-hole sediments are not what,~ne 

would expect to find in marine sediments.;, . fphe · 

predominant salt is calcium carbonate. No sulf~1.te 

was noted, either visually or by chemical. tests 

(Johnson and others, 1967, tahle 7). Sulfides 

are present, but they are much les.."; common than 

in the marine sediments in the Richgrove core 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRA:r...~ CALIFORNIA C41 

or in the nonmarine sediments associated with 

sulfate-rich water in the Los Banos-Kettleman 

City area. The scarcity of chloride salts is suggested by the absence of detectable chloride in four 

clayey sediments from the cores (table 14). 

3. Comparison of the clay-mineral assemblages in the 

core holes (fig. 33) with those in San Francisco 

Bay (samples 9-19, fig. 34) and in the drainage 

system of Coyote Creek and Guadalupe River 

(samples 5-7, fig. 34) suggests that the cored sediments are related more closely to the stream 

sediments than to the bay sediments. The ratio 

of illite to montmorillonite, especially, is larger in 

the bay sediments than it is in the cored sediments 

or the modern alluvial sediments. 

RATES OF DEPOSITION 

Two types of inform·ation, the determination of 

fresh-water fossils and a radiocarbon date, provide impressions of the rates of deposition in the Santa Clara 

Valley. 

Fluminwola yatesiana, which is not believed to be 

younger than late Pliocene, was found at a minimum 

depth of 760 feet in the Sunnyvale core. Assuming 2 

million years as the age of the fossils, the maximum 

average rate of deposition of the upper 760 feet of the 

Sunnyvale core, taken as a whole, must be less than 1 

foot in 2,500 years. Considering that the upper 760 

feet of the core contains deposits of several types, however, this rate should not be applied indiscriminately to 

the whole sequence. 

The carbon -14 content was measured in a piece of redwood recovered from a depth of 73 feet in the San Jose 

core. According to Meyer Rubin,1 who made the 

carbon-14 analysis, the age of the wood is 14,350±400 

years before the present. The upper 73 feet of sediment 

at the San Jose coring site, therefore,. was deposited at 

an average rate of 1 foot in 200 years. ··This rapid rate 

is not necessarily incompatible with the slower inferred 

rate of deposition of the Sunnyvale core. It could well 

·~ represent the post-Wisconsin backfilling of a trenched 

valley of Coyote Creek that was graded to a sea-level 

stand 250-300 feet below present sea level in Wisconsin 

time. This trenching and backfilling is characteristic 

of coastal streams in California (Poland, Piper, and 

others, 1956, p. 28-32, 44:--48; Upson, 1949). The backfilling ancestral Coyote Creek was graded to a rapidly 

rising sea level which stood, according to Curray's 

(1960, p. 253-257) data from the gulf coast, 200-250 

feet below its present level 14,000 years ago. The site 

of the Sunnyvale core, being away from the courses of 

1 Geological Survey Isotope Geology Laboratory sample W-1145, 

July 1,962 .• 

the major valley streams, would not have experienced 

the postulated trenching and backfilling and thus 

should not be expected to reflect strongly the late Pleistocene fluctuations of sea level in its depositional history. A.t the Sunnyvale site, deposition very likely has 

been relatively continuous from late Pliocene time to the . 

present, at the slower 'average rate. 

PARTICLE SIZES 

The study of the particle sizes in the Santa Clara 

Valley is based mainly on 87 samples from the two core 

holes whose locations are shown in figure 28. The two 

cored sections represent two types-perhaps the two 

extreme types-of particle-size assemblages in the Santa 

Clara Valley. The San Jose core hole, drilled next to 

the present channel of the largest stream in the valley, 

penetrates many coarse-grained alluvial deposits. The 

Sunnyvale core represents the fine-grained deposits that 

were deposited at some distance from the principal 

streams. The estimated mean particle size of the sediments is as follows: 

Estimated mean particle size 

(microns) 

Core hole Number of 

samples Recovered Section as a sediments whole 

Sunnyvale _____________ --- 60 4-8 5-10 

San Jose _______________ -- 27 lQ-20 50Q-l,OOO 

Recovery of core from the San Jose hole was very 

poor-30 percent of the cored interval and 17 percent 

of the section as a whole (table 1)-mainly because of 

the inability of the coring apparatus to recover the 

gravels that make up much of the section. Recovery 

from the Sunnyvale core hole was good and seems to be 

nearly representative of the interval as a whole in. the 

Sunnyvale area. Details of the size analyses are tabulated in table 9; as in the Tulare-Wasco samples, the 

percentiles and other measures were determined by· the 

digital computer from particle-size data provided by the 

Hydrologic Laboratory of the Geological Survey. 

Cumulative curves of some of the samples are given in 

the report by Johnson, Moston, and Morris (1967). 

The fine-grained sediments of the Santa Clara Valley--those deposits that lie some distance from the main 

streams-are represented fairly adequately by the sediments recovered from both the core holes. The measures that describe these sediments ·are shown in figures 

29 and 30. The samples fall mainly into three of the 

Shepard size categories-silty clay, clayey silt, and the 

most silty part of the sand -silt-day category. Thirty 

of the samples (half of them from the San Jose core) 

contained gravel in amounts of 0.1-3.0 percent; only 
042 MECHANICS OF AQUIFER SYSTEMS 

SAND AND 

GRAVEL 

25 

CLAY 

50 

PERCENT Sl L T 

75 SILT 

FIGURE 29.-Sand-silt-clay percentages of sediments 

cored in the 'Santa Clara Valley. Based on data 

from the Hydrologia Laboratory of the U.S. Geological Survey. Triangle subdivisions are those of the 

Shepard nomenclatural systems shown in figures 5A. 

and 19A. 

five samples (all from the San Jose core) contained 

more than 3 percent gravel. Most of the median diameters fall in the fairly narrow range between 2,.,. and 

31p.. Most of the modal di1ameters that could be determined fall, as in the nonmarine sediments of the TulareW·as0o area, between 31p. and 62p.. The modes of 

most of the 44 samples that were not determined presumably should he finer than 31p.. In general, the finegrained sediments are poorly sorted, and their distr-ibutions are skewed toward the finer sizes. 

SPATIA.L DISTRIBUTION OF PARTICLE S~ZES 

The distribution of sediments with regard to depth 

in the uppermost 1,000 feet in the Sunnyvale area (fig. 

31) is fairly uniform : a series of fine sediments interrupted only sporadically hy thin beds ( 10 ft thick at 

most) of sand or gravel. The exceptions to this uniformity are that more sand and gravel beds are found 

in the upper half of the cored interval than in the lower 

half, and that the silts and clays are generaUy finer 

grained in the lower half. The particle sizes seem to 

coarsen progressively between 1,000 and 500 feet, then 

becomes progressively finer again between 500 feet and 

the land surface. 

In the sediments in the uppermost 1,000 feet a;t the 

San Jose coring site, fine sediments, such as those described above, are interbedded with coarser sediments. 

About a third of the interval here is gravel. The fine 

and coarse sediments are approximately equally distributed with regard to depth. The general range in bed 

thickness for both the fine ·and coarse sediments is 5-50 

feet. The contrasts between the coarser gravels and the 

finer .silts and clay, judging from the resistivity log in 

~ ..J 

a.. 

:::!!: 

c( 

en 

1.1.. 

0 

a:: 

UJ 

CD 

:::!!: 

:::J 

z 

15 

0 

SUNNYVALE 

CORE 

SAN JOSE 

CORE 

ALL SAMPLES <87> 

4 62 1000 4 62 

MEDIAN DIAMETER, IN MICRONS 

1000 

SAMPLES <43> WHOSE MODES 

COULD BE DETERMINED 

4 62 1000 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

':tL 

4 

15 

0 

15 

0 

0 

15 

62 1000 4 62 1000 

MODAL DIAMETER, IN MICRONS 

SAMPLES (62> WHOSE QUARTILES 

COULD BE DETERMINED 

4 62 1000 4 62 1000 

MEDIAN DIAMETER, IN MICRONS 

2 0 2 

QUARTILE DEVIATION (QDif>) 

0 0.4 -0.4 G 0.4 

QUARTILE SKEWNESS (::) 

FIGURE 30.-Measures of average size, sorting, and 

skewness in sediments cored in the Santa Clara 

Valley. 

figure 31, are abrupt. There seems to be little mwterial 

of "average" size that grades between the fine and coarse 

materials. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C43 

~ 

0 

-I 

UJUJ 

!DU c( I-Ll.. 

UJO:: 

UJ::::~ 

u.en 

~Q 

.z 

J:c( 

f--1 

a.. 

UJ 

Q 

0 

500 

1000 

SUNNYVALE 

CORE 

MEDIAN DIAMETER, 

IN MICRONS 

1 8 62 500 

0 

500 

SAN JOSE 

CORE 

MEDIAN DIAMETER 

IN MICRONS 

8 62 500 4000 

I • ' • • • 

FIGURE i31.-Variations in particle size with depth, Santa Clara 

Valley. Resistivity log is left column of each composite; range, 

from left to right, is 0-50 ohms m2/m. 

Because of the differences in grain size, the sediments 

in the two cores should be expected to respond differently 

to compaoting pressures. The Sunnyvale sediments, being mostly silt and clay, should be compacted more per 

unit load, but their rate of compaction might be retarded 

by their uniformly low permeability. The San Jose 

sediments, because they contain more gravel layers, 

should be compacted less under the same unit load, but 

their rate of compaction should be greater because the 

gravel layers provide permeable routes for the escape of 

water. 

INTERRELATIONS OF PARTICLE-SIZE MEASURES 

Figure 32 shows the graphs of median diameter 

against the c.oarsest percentile (C) , sorting, and skewness for the alluvial depos~ts of the Santa Clara Valley. 

Not included in the graphs are samples that .contain cement, fossil mollusks, or interlam.inations of sediment of 

different sizes. The measures of sorting ( Q D q,) and 

ske,vness (Skq q,/QD"' and Skqq,) are defined on .page 

C49. The reasons for graphing these measures against 

median diamelter are reviewed on pages C13-C16. 

The graphs of median diameter against sorting and 

skewness for the alluvial sediments of the Santa Clara 

Valley (fig. 32) show about the same relations as the 

corresponding graphs for the alluvial-fan sediments of 

the Los Banos-Kettleman City area (fig. 12): the best 

sorting in sediments having median diame~ers between 

125p. and 500p., poorer sorting in the finer sediments; the 

greatest ske,vness in sediments having median diameters 

between 16p. and 62p., and progressively less skewness in 

finer and coarser sediments. 

The CM pattern (top graph, fig. 32), however, does 

not give much insight into the processes of deposition. 

Many of the sediments contain isolated granules or pebbles, seemingly distributed at random, whose presence 

produces a wide scattering of C values. How these pebw· 

-I 

i=en 

zz 

UJQ Ua:: 

a::u UJa..;:E 

1-z en_ 

a:: 

Li: 

wO' ~ ..J'-

i=z 

a::o 

<- ::::1!;( 

0-

> UJ 

Q 

~ 0' 

....... 

UJ~ ~ 

~~ 

<en -len 

UJUJ 

a::z 

~ UJ 

~ 

en 

......_ 

~ 

UJ~ ~--~ 

::len -len Ow 

enz 

Ill~ c(UJ 

~ 

en 

0.5 2 8 31 125 500 2000 

64,000 r-o---r--.-.....--r-r--r--r--r-..-......--. 

16,000 

4000 

1000 

250 

62 

.. ., . ... . : ·~ . • 

. . .•. !!. .. ·:~~ •\J ~'"' .-- -r~' .... G 

-

• 

4 16 62 250 1000 

3- ••• --,. 2 -... !.If· 

1 -• • •• • 

0.6 I 

0.4 

0.2 . ·., . ·-~· . ., . • • 

0 • • 

-0.21-

1- • 

-0.4 

1.2 

•• 0.8 .. ... 0.4 

..... 

.·~. , 

0 .. . • 

-0.4 

-

• -

• 

-

• • 

• 

• -

• -

-

-

• 

• • • 

4 16 62 250 1000 

MEDIAN DIAMETER, 

IN MICRONS 

FIGURE 32.-Median diameter against 

coarsest percentile, sorting, and skewness 

m alluvial sediments, Santa Clara Valley. 

bles and granules came to be deposited with otherwise 

fine sediments is not clear. 

CLAY MINERALS AND ASSOCIATED IONS 

CLA Y·MINERAL ASSEMBLAGE 

The principal clay mineral in the upper 1,000 feet of 

sediments of the Santa Clara Valley, as in the areas of 

land subsidence in the San Joaquin Valley, is mont-
C44 MECHANICS OF AQUIFER SYSTEMS 

morillonite. Other constituents of the clay-mineral 

assemblage are chlorite (type B) and illite, plus trace 

amounts of low-grade illite-montmorillonite. The distribution of the clay minerals in the fine-grained sediments in the Sunnyvale and San Jose cores is represented in figure 33. Clay minerals in the near-surface 

sediments are shown in figure 34. Details are given in 

tables 14 and 15. Identification criteria and the method 

of estimating relative proportions of clay minerals are 

also given on pages C67 -C71. Assuming that the 20 

core-hole samples are representative, the average claymineral composition of these sediments isOlay minerals Percent 

Montmorillonite -------------------------- 70 

Chlorite --------------------------------- 20 

Illite ------------------------------------ 5-10 

Low-grade illite-montmorillonite -----------Trace 

The 12-A chloritic mineral, although present in the surface sediments, was not detected in the core-hole sediments. 

0 

0 

UJ 

() 

<( 

LL. 

0::: 

::::l 

en 

Q 

z 

<( 

..J 

~ 

0 

..J 500 UJ 

III 

1-

UJ 

UJ 

LL. 

~ 

:i 

1-

a.. 

UJ 

Q 

1000 

CLAY MINERALS 

(ESTIMATED PARTS PER TEN) 

5 

SUNNYVALE 

CORE 

= 

10 0 

0 

500 

5 

SAN JOSE 

CORE 

10 

·-

1000 

EXPLANATION 

Montmorillonite 

-

D 

Illite 

Chlorite 

FIGURE 33.-Clay minerals in cored sediments, Santa Clara 

Valley. Trace amounts not illustrated. Determined with 

tbe assistance of J. B. Corliss. 

The abundant montmorillonite must be derived 

largely from the weathering of the rocks of the Franciscan and Knoxville Formations, especially the shales, 

graywackes, and greenstones that are abundant in this 

rock assemblage. The chlorite and illite, likewise, are 

probably derived from fine-grained constituents of these 

sediments. The difference between this assemblage and 

the better crystallized assemblage of clay minerals, also 

from the Franciscan Formation, in Little Panoche 

Creek and the upper part of the Oro Lorna core in the 

Los Banos-Kettleman City area (figs. 13, 14) may be 

related to different degrees of metamorphism in the 

source terranes. 

TOTAL CLAY-MINERAL CONTENT OF SEDIMENTS 

The estimates of the total clay-mineral content were 

made on the same basis as for the sediments of the Los 

Banos-Kettleman City and Tulare-Wasco areas. 

Clay minerals probably make up 30-35 percent of the 

section of fine sediments penetrated by the Sunnyvale 

core hole. Montmorillonite, therefore, probably makes 

up 20-25 percent of the section. In the coarser sediments penetrated by the San Jose core hole, the amount 

of clay-mineral material is substantially less--on the 

order of 10 or 15 percent. In other parts of the Santa 

Clara Valley the amount of clay-mineral material in the 

alluvial sediments probably ranges between 10 and 35 

percent. 

EXCHANGEABLE CATION-S 

The principal ions associated with the sediments in the 

Sunnyvale and San Jose cores are calcium, magnesium, 

bicarbonate, and a little sodium. Details are given in 

table 14. 

The cations adsorbed by the clays in the cored sediments are represented in figure 35. The adjusted sum 

of the cations exceeds the cation-exchange capacity substantially (by a factor of 2 or more) in 7 of the 20 

samples. Calcite was visible in these seven samples, 

and the difference between the adjusted sum and the determined capacity probably reflects the greater solubility of calcite in cold NH4Cl solution (in which the 

cations were determined) than in hot water (in which 

the anions were determined). Calcium, nevertheless, 

is the principal exchangeable cation. In the sediments 

in which the adjusted sum of cations is elose to the cation-exchange capacity, calcium accounts for two-thirds 

to three-quarters of the exchangeable-eation equivalents. 

Magnesium eomrpletes the exchangeable-cation assemblage in all but. the four samples near the bottom of the 

Sunnyvale core that contain exchangeable sodium. 

The water from neighboring wells that is being 

pumped from the coarse-grained sediments in the same 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C45 

122"15' 122"00' 121 "45' 

37"30' 

Agnew • 

® 

Core-hole location 

.a 

Sample location 

Number corresponds to 

that in table 15 

/1/////T/// 

Boundary of Santa Clara Valley as 

denoted by boundary between 

alluvial deposits and consolidated 

rocks 

Mountain• 

View 

•sunnyvale 

EXPLANATION 

- 1- Montmorillonite 0 

D c. 

1-

Illite .).. 

7 

~ 

, 

1-

Chlorite \S'I 

Kaolinite-type 

-

mineral 

37"15' mtml 

Chlorite and kaolinitetype mineral 

0 2 3 4 5 MILES 

ffiB 

Santa 

Clara • 

Campbell• 

4

1 .. -rnEBI 

FIGURE 34.-Location of core holes and sampling sites for clay minerals in Recent surface alluvial and bay-bottom sediments, Santa Clara 

Valley. Minerals in samples 1-11 determined with assistance of J. B. Corliss, T. J. Cono·mos, and J. 0. Berkland. Samples 12-19 

collected and analyzed by T. J. Conomos. 

depth interval as the core, and which is perhaps in near 

chemical equilibrium with the fine-grained sediments, 

has approximately the following chemical characteristics : 

Total dissolved solids __________________ ppm __ 4()() 

Na (percent of total cation equiYa1Pnt~) __ 25 

Ca/Mg ratio (of equivalent~)------------ 1. i"")-2. 0 

These data are summarized from the more complete 

analyses listed in tables 16 and 17. Because the wells 

in the Sunnyvale area produce ground water from large 

depth intervals, rather than from selected smaller depth 

intervals, one cannot tell whether the increase in exchangeable sodium in the sediments near the bottom of 

the Sunnyvale core hole is related to a downward increase in the dissolved sodium or to a downward increase 

in the total disssolved solids in the ground water. 

CLAY MINERALS IN THE ARVIN-MARICOPA AREA 

The trea;t.ment that the sediments of the Arvin-Maricopa area are given in this report is very brief, for it is 

based on only eight samples from a test hole drilled near 

Lakeview in Kern County (location shown in fig. 36). 

The main purpose of this hole was not to obtain core, 

and only a few samples were taken (table 1). The 
C46 MECHANICS OF AQUIFER SYSTEMS 

0 

0 -

UJ 

(.) 

<( 

LL.. 

a:: 

:::> 

(/) 

0 

z 

<( 

...J 

~ 

0 

...J 500 UJ 

aJ 

1-

UJ 

UJ 

LL.. 

~ 

:i 

1-

a. 

UJ 

0 

1000 

EXCHANGEABLE CATIONS 

(ADJUSTED PERCENT EQUIVALENTS) 

50 

SUNNYVALE 

CORE 

100 

I 

J 

I 

I 

J 

I 

I 

I 

I 

• 

• 

-

0 

0 -

500 -

1000 -

EXPLANA Tl ON 

IZ8I 

Calcium 

D 

Magnesium 

Sodium 

-

50 

SAN JOSE 

CORE 

100 

I 

I 

I 

I 

I 

I 

I 

J 

FIGURE 35.-Cations ad·sorbed by clay minerals in cored sediment, Santa Clara Valley. Determined by H. C. Starkey 

and Toribio Manzanares, Jr. 

geology of the area and of the drilled deposits are summarized by Wood and Dale (1964). The land subsidence in the area is described by Lofgren (1963). Only 

the clay minerals are described here. 

Montmorillonite is the principal clay mineral in the 

fresh-water-bearing sediments of the Arvin-Maricopa 

area. Subsidiary clay minerals are illite, chlorite, and 

a kaolinite-type mineral. Clay minerals in the sediments cored in the Lakeview test hole are represented 

in figure 37. Details are given in table 18. Assuming 

that these eight samples are representative, the average 

clay-mineral composition of the water-bearing sediments isClay mineral.~ Percent 

~Iontmorillonite -------------------------- 7ri 

Illite ------------------------------------ 10 

Chlorite --------------------------------- 10 

Kaolinite-type mineraL___________________ ti 

The sediments that were pierced by the Lake view test 

hole, and presumably the included clay minerals, seem 

to have been derived from a metamorphic and silicicigneous terrane. The nearest and most likely such terrane is in the San Emigdio Mountains, to the south of 

the Arvin-Maricopa area. llowever, as only 37 feet of 

core (from 65 ft of cored interval, see table 1) was recovered from the test hole, the source can be identified 

on a tentative basis only. The main constituents of the 

gravels and the lithic grains in the sands recovered from 

this hole are fragments of metamorphic (schistose rocks, 

marble, hornfels, quartzite, serpentine) and megascopically crystalline silicic igneous rocks (mainly diorite). 

The sands are light colored. Biotite and hornblende 

grains are present but only 'amount to a percent or so of 

the sands. 

Because so little core was taken from the Lakeview 

hole, no estimate was made of the total clay-mineral 

material in the sediments. Neither were the exchangeable cations determined. 

SUMMARY OF RESULTS OF PETROLOGIC STUDY 

The fresh-water-bearing sediments, mostly Pliocene 

to Recent in age, that lie beneath the three major areas 

of land subsidence in the San Joaquin and Santa Clara 

Valleys of Californi~ consist of detritus from the Sierra 

Nevada and the Coast Ranges. They are mostly alluvial, having been deposited on alluvial fans or on the 

fi'OOd plains of perennial streams. The sediments also 

include shallow-marine, lacustrine, and deltaic deposits, 

but these are less abundant than the alluvial deposits. 

Because the particle sizes are so diverse, they are not 

easily summarized in a few sentences. Numerical averages, although they give some general impression of 

the sizes of the particles, are of limited significance. 

The geometric-mean particle size of all the sediments 

is probably in the coarse-silt range, 30,u to 60p. The 

most abundant sediment type, according to the Shepard 

classification, is clayey silt; other abundant types are 

sand-silt-clay and silty sand. 

The alluvial sediments, as well as being the most 

abundant sediment types, are also the most diverse in 

their size characteristics. They range from gravels to 

silty clays. The alluvial sediments in the Los BanosKettleman City area have a mean particle size between 

30,u and 60,u and a modal size between 125,u and 

250,u. Those in the Tulare-,Vasco area have a mean 

size between 40,u and 80,u and a modal size between 

30ft and 60ft. Note that although the Los Banos-Kettleman City sediments have a finer mean size than the 

Tulare-Wasco sediments, their modal size is coarser. 

The mean sizes of the alluvial sediments in the Santa 

Clara Valley range from rruther -coarse (500ft to 1,000,u) 

beneath the major streams to rather fine (51-' to lOft) 

a way from the axis of the valley. The general degree 

of sorting of all the alluvial sediments is fair-to poor 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C47 

R. 23 W. R. 24 W. R. 25 W. R. 26 W. R. 27 W. R. 28 E. R. 29 E. R. 30 E. R. 31 E. 

I 

I 

Britton willow T. 29 S. t--.=7: =:;_=.;=:.:...._-+-----. 

I I I I : .-· 

1 I I I -- .r' ---T-------t ---------;---- ~-~~:s;.k;;;iieldl.( 

: I _,-.J : 

T. 30 S. 1 1.·· 1 

---~ : 

( 

T. 31 S. 

T. 32 S. 

T. 11 N. 

R. 23 W. 

I 

I 

I 

-------~---~~~'~,,-,,, 

I {t\ 

I 

I 

Arvin i 

I 

I 

-------+-- 1 

I 

)> 

)> 

"&~~~ 2 0 2 4 6 8 MILES 

Boundary of 

consolidated rocks 

FIGURE 36.-Arvin-Maricopa area showing location of Lakeview test hole. 

(average Q D <i> near 2.0). Skewness measures indicate 

a disproportionately large admixture of finer particles. 

The interrelations of the particle-size measures (median 

diameter versus sorting, skewness, and the coarsest percentile) provide some insights into depositional processes, but they do not provide a unique means of interpreting the histories of alluvial sediments. 

Montmorillonite is the predominant clay mineral in 

nearly all the sediments, regardless of their source terranes or their environments of deposition. It comprises 

60-80 percent of the clay-mineral assemblages and 5-25 

percent of the different sections of sediments whose compaction accounts for the observed land subsidence. The 

uniform preponderance of montrnorillonite in clay-mineral assemblages derived from diverse source terranes 

(Sierra Nevada, Coast Ranges, and, in the Arvin-Maricopa area, the Transverse Ranges) and deposited in 

diverse environments (marine as well as nonmarine) 

implies some sort. of pervasive influence on the claymineral assemblages. The identity and nature of this 

influence, however, a wait further study. 

Calcium is the principal exchangeable cation adsorbed by the clay minerals. Other adsorbed cations 

are magnesium, sodium, and hydrogen. The proportion of adsorbed sodium increases with increasing depth, 

probably reflecting a corresponding downward increase 

in the sodium content of the associated interstitial 

waters. In some of the marine siltstones of the TulareW aseo area, calcimn is replaced in the exchange positions by the other cations, under the influence of locally 

acid eonditions aecompanying high concentrations of 

sulfate. 

Four petrologic eharacteristics are probably the most 

important to the understanding of the compaction behavior of these sediments: ( 1) the general fineness of 

the particle sizes, (2) the diverse juxtaposition of coarser and finer deposits, ( 3) the large proportion of montmorillonite, and ( 4) the downward increase in the proportion of adsorbed sodium relative to adsorbed calcium. 

As shown by studies reviewed in an earlier report in this 

series (Meade, 1964, fig. 3), finer sediments are more 

porous under a given load and more compressible under a gi•v.en change in load than coarser sediments. The 

interbedding of coarser la.yers with the finer deposits 

provides permeable avenues of escape for the water 

squeezed from the finer deposits. Laboratory studies 
C48 MECHANICS OF AQUIFER SYSTEMS 

LIJ 

·u 

<( 

u. 

c:: 

0 

CLAY MINERALS 

(ESTIMATED 

PARTS PER TEN) 

0 5 10 

~ 500--···-=~~ z 

<( 

...J 

3: 

0 

...J 

LIJ 

al 

~ LIJ 

u. 

•m; 

•;m 

~1000 

J: 

!i: 

LIJ 

0 

1500 

-

EXPLANATION 

Montmorillonite 

-

D 

Illite 

Chlorite 

Kaolinite-type 

-

mineral 

-

-

Chlorite and kaolinite-type 

mineral 

FIGURE 37.--clay minerals in 

cored sediments from Lakeview test hole, Arvin-Maricopa area. Trace amounts 

not illustrated. Determined 

with the assistance of F. P. 

~augler and J. B. Corliss. 

by several workers, summarized earlier (Meade, 1964, 

fig. 4), show that clays rich in montmorillonite are more 

porous •and more compressible under a given load or 

change in load than clays that consist mainly of the 

other clay minerals. And, finally, other laboratory 

studies (Meade, 1964, fig. 11) show that montmorillonite which has adsorbed sodium as its exchangeable cation is more porous under a given load than montmorillonite whose exchange positions are saturated with calcium. The next report in this series (Meade, R. H., 

Compaction of sediments underlying areas of land subsidence in central California, in preparation for publication as Prof. Paper 497-D) considers in more detail 

the relations of the petrologic characteristics to the 

observed compaction of the sediments. 

DETERMINATION AND DESCRIPTION OF PARTICLE 

SIZES 

SAMPLING AND PARTICLE-SIZE ANALYSIS 

Samples for particle-size analysis were taken, whereever possible, from each 10 feet of cored interval. A 

consistent attempt was made to take "average" sampies-that is, the sample frotn each 10-foot interval that 

seemed to be the most representative of material in the 

interval. Sampling, as a result, was not random, but 

was biased toward the visually estimated "average" 

sediment. 

The sampling was also biased toward the finer sediments in the sections. The coring apparatus was unable to recover much of the loose gravel and well-sorted 

coarser sands, whereas it recovered easily the more cohesive clays, silts, fine sands, and poorly sorted sands. 

Not all the coa.rser material was lost, however--some 

well-sorted coarse sand and even a little loose gravel 

was recovered-and not all the unrecovered material 

was coarse grained. Some of the lost material was fine 

sediment that was not recovered because of occasional 

lapses in the efficiency of the coring procedure. 

The two sources of sample bias-selectivity in coring 

and selectivity in sampling of the recovered core materials-limit the statistical use that can be made of the 

data on particle-size distribution. For example, one 

cap estimate the mean particle size of the sediments as 

a whole only within widely spaced limits. On the other 

hand, the particle-size data can be used in a descriptive 

way and can be helpful in understanding the history 

and properties of the sediments-as long as one keeps 

in mind that the samples were not taken at random and 

that sampling of the coarsest and very finest sediments 

was especially inadequate. 

Particle-size analyses of the samples were made in the 

Hydrologic Laboratory of the Geological Survey by 

standard wet sieve and hydrometer ~pethods. The 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C49 

procedures and results are given in the report by A. I. 

Johnson, R. P. Moston, and D. A. Morris (1967). 

DESCRIPTION OF PARTICLE SIZES 

Because most of the sediments treated in this report 

are fairly fine, the particle sizes are expressed in microns 

(p.). The size-grade intervals used to express median 

and modal diameters in figures 6-12, 20-23, and 30-32 

are those suggested by the National Research Council 

(Lane and others, 1947, p. 937), as given in the followingtable. 

Grade 1 

Coarse graveL __________________________ _ 

Medium graveL ________________________ _ 

Fine graveL ____________________________ _ 

Very fine graveL _______________________ _ 

Very coarse sand ________________________ _ 

Coarse sand ____________________________ _ 

Medium sand __________________________ _ 

Fine sand ______________________________ _ 

Very fine sand __________________________ _ 

Coarse silt _____________________________ _ 

Medium silt ____________________________ _ 

Fine silt _______________________________ _ 

Very fine silt __________ . _________________ _ 

Coarse clay ____________________________ _ 

Medium clay ___________________________ _ 

Fine clay ______________________________ _ 

1 I,ane, E. W., chm., and others, 1947, p. 937. 

32,000 

16, 000 

8,000 

4,000 

2,000 

1,000 

500 

250 

125 

62 

31 

16 

8 

4 

2 

1 

.5 

cfJ 

-5 

-4 

-3 

-2 

-1 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

The phi-notation system for particle sizes was used 

to compute some of the measures of sorting and skewness. Phi ( </>), ·as defined by its originator Krumbein 

(1934), is the negative logarithm to the base 2 of the 

grain dia;meter : 

c/>== - log2N, 

where N is the grain diameter in millimeters. The advantages of this system are that it converts a geometric 

grade scale to an arithmetic one and "permits the application of common statistical procedures to the data" 

(Krumbein, 1936a, p. 35). The system and its advantages are discussed further by l{rumbein ( 1934, 1936a, 

b). Phi values are included in the table above. Note 

that one whole </> interval corresponds to one grade in 

the N rutional Research Council classification. 

Selected percentiles, mean sizes, and measures of sorting and skewness, derived graphically from the cumulative curves or interpolated from particle-size data by 

a digital computer are given in tables 5-9. ( Cumulative curves of some of the samples are given by Johnson and others, 1967.) Inman (1952, p. 125) suggests 

the inclusion of the following percentiles in a description of grain-size distributions: 5th, 16th, 50th (the 

median diameter, 31 d), 84th, and 95th. These are given 

in the tables, along with the 1st percentile ( C, used in 

an interpretive method devised by Passega, 1957) and 

the 25th and 75th percentiles (the 1st and 3d quartiles, 

used in well-known measures of sorting and skewness 

devised by Trask, 1930, and Krumbein, 1936b). Percentiles ·are given in microns and phi units. The following measures, computed from the percentiles, are 

also tabulated for the benefit of those interested in specific numerical data. 

Me~,~Sure Symbol Formula Reference 

Median __ ------------ Md 5oth percentile, taken directly from the distribution curve and expressed 

either in "' mm, or ctJ. Means Inman (1952, p. 133- ________________ Mq. ~(ctJto+ctJ84) 134). 

QMq. WctJu+ctJn) Deviations (sorting uq. ~(ctJu-cfJ1&) Inman (1952, p. 135-

indexes). 136). 

QDq. ~(ctJ7s-ctJu) Krumbein (1936b, p. 102-103). Skewness measures ___ aq. Mq.-Mdq. Inman (1952, p.137). 

uq. Skqq. QMq.-Mdq. Krumbein (1936b, p. 107-110). 

Skqq.fQDq. QMq.-Mdq. Waugh (1952, p. 202-

QDq. 203). 

Sk PuPn/Mdz Trask (1930, p. 594). 

The quartile measures of sorting and skewness, QDctJ 

and Skqc~JfQDctJ, are used in describing these sediments. 

The measures O"~ and a~ are recommended over quartile 

measures by Inman ( 1952, p. 126), among others, because they describe more of the sample-two-thirds instead of half-and because they are analogous to the 

moments of the normal frequency distribution generally used in statistics. Unfortunately, the sediments 

described in this report were so fine tha;t the 84th percentile, necessary to the computation of O"c~J and actJ, was 

not determined in many samples. The finest grain size 

determined in the hydrometer analyses was l.Op.. In 

many of the sediments, especially those from the Los 

Banos-Kettleman City area and the Santa Clara V·alley, the 84th percentile was below l.Op.. Because the 

third quartile (75th percentile) was l.Op. or larger in 

many more of the sediments and could be used to compute sorting and skewness measures, quartile measures 

were used. 

Although a digital computer and a program were 

available to compute the actual moments of the size dis-
C50 MECHANICS OF AQUIFER SYSTEMS 

tributions, rather than such graphical analogues of the 

moments as CT"' and QD"', the moments were not computed. Because the finer parts of the size distributions 

were not determined in detail, the graphical measures 

based on measured percentiles are prdbably as accurate 

a portrayal of sorting and skewness as moments calculated from size distributions whose finer parts have to 

be assumed. 

SXQq>/QDq>, OR BOWLEY'S MEASURE OF SKEWNESS 

Because Bowley's measure of skewness, Skq.pfQD"', 

has not. been applied to sediments before, as far as I 

know, an expanded discussion is given here to relate it 

to the measures of skewness that are already established 

in the litera:ture of sedimentology. 

In spite of the fact that the particle-size distributions 

of most sediments do not follow the normal or lognormal probability law (Pettijohn, 1957, p. 40-42), the 

distribution parameters derived from probability theory are valuable for describing particle-size distributions and for comparing one distribution with another. 

This is particularly true of skewness measures. They 

"are used m·ainly in descriptive statistics; in experimental work, if a distribution is found to be skew, it is 

better to seek a transform·ation of the variable which 

will yield a nearly symmetrical distribution and carry 

out the necessary calculations in terms of the new varia:ble" (Davies, 1957, p. 37). Because their use is mainly 

descriptive, measures of skewness can be designed to 

show different characteristics of frequency distrihutions. Some skewness measures,. for instance, show the 

absolute difference between two measures of central 

tendency; other relative measures show more clearly the 

asymmetry of the distribution. Bow ley's measure of 

skewness is a measure of asymmetry. 

Waugh (1952, p ... 203) gives the formula for Bowley's 

measure of skewness: 

Qa + Qt- 2 median 

Qa-Qt . 

Substituting phi notation and dividing numerator and 

denominator by 2, we have 

7'2(cl>7s+<l>2s)-M dtf> 

7~(cf>7s-cb'Js) ' 

which is 

QM"'-Md"' Skq"' 

QD"' ' or QD"'. 

Rather than introduce a new symbol, I prefer to 

express it as a fraction of two well-known sym bois 

introduced by Krumbein (1936b, p. 102-103, 107-110). 

All the possible values of Skq"'/QD"' fall between -1.0 

and +1.0. 

Skq<t>/QD.p gives a clearer impression than Skq"' of the 

asymmetry of a particle-size distribution. Skq,p is the 

difference between the quartile mean (QM.p) and thP. 

median diameter (Md"'). In using Skq"', one can 

assign equal skewness values to a slightly asymmetrical 

poorly sorted sediment and a strongly asymmetrical 

well-sorted sediment. Dividing Skq"' by QD"' makes it 

a simple measure of asymmetry and less dependent on 

the spread of the distribution. 

The relation of Skq<t>/QD"' to another established 

measure of skewness, Sk (Trask, 1930, p. 594), is shown 

in figure 38. Positive values of Skq<t>/QD.p are associated 

with negative values of the logarithm to the base 10 

of Sk. The numerical relation between the two measures varies with changes in the value of QD"'. In a 

sediment for which QD"'=1.67, Skq,pfQD<P=-log1oSk. 

This is confirmed in a conversion chart given by Krumbein and Pettijohn (1938, p. 237) in which Skq,p= 

-1.67logtoSk. 

Waugh (1952, p. 203) points out that Bowley's 

measure of skewness can be extended to include more 

of the distribution curve by using any two percentiles 

equidistant from the median. Inman (1952, p. 137) 

has done essentially this in his measure of skewness, 

arp, which is expressed as 

cl>s4+c/>t6-2Md"'. 

cP84-c/>J6 

The relation between Skq"'fQD"' and a"' is very close. 

In fact, in a particle-size distribution in which the 

asymmetry is not progressive toward the extremes of 

the distribution, Skqq,jQD"' and a"' are numerically 

equal. 

TABLES OF PARTICLE-SIZE-DISTRIBUTION DATA AND 

DERIVED MEASURES 

The remainder of this part of the report consists of 

five tables, 5-9. Table 5 contains selected particle-size 

data for 305 samples from the Mendota, Cantua Creek, 

and Huron cores of the Los Banos-Kettleman City area. 

Table 6 contains particle-size data for a group of fine 

sediments from the Los Banos-Kettleman City area in 

which the exchangeable cations and soluble anions were 

determined. (See tables 11, 12.) Table 8 contains 

particle-size data for 157 core-hole samples from the 

Tulare-Wasco area. Table 9 contains data for 87 corehole samples from the Santa Clara Valley. Particle 

sizes in these sam pies were determined in the Hydrologic 

Laboratory of the lT.S. Geoloiical Survey; the sample 

numbers are those assigned by the laboratory. Table 7 

contains the results of sieve analyses (finest sieve 0.062 

mm) of selected well-sorted sands. 

Although the samples in tables 5-7 were all from the 

Los Banos-Kettleman City area, they were not combined 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C51 

0.5 

-0.5 

-0.5 0 

log10 Sk 

0.5 

FIGURE 38.-Relation between Skq.fQD. and log10 Sk. 

1.0 

into one table because they represent three different 

groups of sediments that were sampled for three different purposes. That is, the samples in each group are 

biased in different ways. 

The percentiles in tables 5-7 were interpolated by eye 

from the smoothed cumulative curve drawn from the 

particle-size data. The other measures in tables 5-7 

were computed from the percentiles, using a desk calculator. The percentiles in tables 8 and 9 were interpolated from particle-size data by a digital computer. 

The other measures in tables 8 and 9 (except for the percent finer than 3p.) were also calculated by the computer. 

The measures reported in tables 8 and 9 may be different from corresponding measures in the same samples 

as reponed by the Hydrologic Laboratory (Johnson 

and others, 1967). The differences reflect Jthe :fuot that 

Johnson ·and his coworkers determined the measures by 

eye from the smoothed cumulative curves. 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area 

Sample 

57 CAL L. -----

57 CAL 2 ______ _ 

57 CAL 3 ______ _ 

57 CAL 4__ ____ _ 

57 CAL 5a _____ _ 

57 CAL 5b ... __ 

57 CAL 6 ______ _ 

57 CAL 7 ______ _ 

57 CAL 8 ______ _ 

57 CAL 9 ______ _ 

57 CAL 10 _____ _ 

57 CAL 11 _____ _ 

57 CAL 12 _____ _ 

57 CAL 13 _____ _ 

57 CAL 14 _____ _ 

57 CAL 15 _____ _ 

57 CAL 16 _____ _ 

57 CAL 17 _____ _ 

57 CAL 18__ ___ _ 

57 CAL 19 _____ _ 

57 CAL 20 _____ _ 

57 CAL 2L ___ _ 

57 CAL 2L ___ _ 

57 CAL 23 _____ _ 

57 CAL 24 _____ _ 

57 CAL 25 _____ _ 

Depth 

below 

land 

surface 

(feet) 

77 

111 

153 

192 

233 

233 

277 

314 

353-

398 

432 

472 

511 

553 

594 

631 

647 

653 

662 

674 

683 

697 

707 

713 

722 

731 

1 

(C) 

220 

2.2 

410 

1.3 

720 

0.47 

220 

2.2 

320 

1. 6 390 

1.4 

2,500 

-1.3 

240 

2.1 

410 

1.3 

49 

4.4 

290 

1.8 

230 

2.1 

1,100 

-0.13 

340 

1. 6 310 

1. 7 370 

1. 4 

60 

4.1 

380 

1. 4 

62 

4.0 

68 

3.9 

440 

1.2 

62 

4. 0 440 

1. 2 

50 

4.3 

120 

3.1 

78 

3. 7 

I 

5 

150 

130 

460 

150 

210 

260 

740 

160 

260 

22 

91 

170 

250 

200 

130 

240 

35 

280 

33 

35 

310 

33 

390 

31 

50 

37 

I 

Percentiles (mic~ons) 

16 

85 

3.6 

35 

320 

1.6 

91 

100 

170 

2.6 

530 

0.92 

92 

170 

2.6 

9.6 

22 

120 

3.1 

14 

93 

15 

92 

19 

140 

22 

19 

5. 7 

150 

2. 7 

21 

5.6 

330 

1.6 

22 

5. 5 

23 

5.4 

23 

5.4 

I 

25 

61 

4.0 

19 

280 

1.8 

69 

3.9 

45 

150 

2. 7 

430 

1.2 

56 

4.2 

130 

2.9 

6.3 

9.5 

97 

3.4 

5.3 

49 

5.0 

30 

5.1 

13 

49 

4.4 

17 

5. 9 

14 

6. 2 

81 

3.6 

17 

5. 9 310 

1.7 

18 

5.8 

18 

5.8 

17 

5.9 

I 

50 

(Md) 

24 

5.4 

3.4 

8.2 

230 

2.1 

27 

5.2 

4.6 

7.8 

91 

3.5 

250 

2.0 

19 

5. 7 

60 

4.1 

1.1 

9.8 

2.0 

9.0 

58 

4.1 

0.8 

10.3 

6.1 

7.4 

1. 2 9. 7 5. 7 7.5 

3.6 

8.1 

9.6 

6. 7 5.8 

7.4 

6.8 

7.2 

13 

6.3 

8.2 

6.9 

250 

2. 0 

10 

6.6 

12 

6.4 

6.6 

7.2 

I 

Means Deviations 

I I M, I QM, I QD, .. I 75 84 95 tT. 

3.8 

8.0 

Mendota core 

1. 5 ------ 6. 5 9.4 

140 89 ------ 2. 6 2.8 3.5 

4. 5 -------- ------ -------- 7.8 

14 

6.2 

170 

2.6 

3.3 

8.2 

11 

6.5 

24 

5.4 

1.8 5.8 9.1 

140 ------ 1. 9 2.8 

1. 7 ------ 5. 9 

9.2 

8. 3 ------ 5. 0 

6.9 

6.0 2.9 

2.3 .9 

5.8 --------

4.4 

1.9 

6.2 

4. 7 

4.4 

3.3 

1.0 

3.3 

1. 9 

2.0 0.37 

.5 .48 

2. 0 --------

1.7 .73 

.7 -.12 

2.0 

1.8 .55 

1.0 .45 

0.9 -------- ------ -------- 7.6 -------- 2.5 -------- 10.1 

1. 8 -------- ------ -------- 9.1 

1.5 

9.4 

2.0 

9. 0 3.2 

8.3 

2. 7 8.5 

110 

3.2 

4.5 

7.8 

8.2 

6.9 

1.9 

9.0 

1.2 

9. 7 

1. 2 

9. 7 

1.4 

9. 5 

42 

4.6 

2.3 

8.8 

6. 0 

7.4 

1.0 

10.0 

7. 7 

6.2 

7.5 

6.4 3.1 

7.1 

6.4 

7. 7 

6. 7 

7.6 

7.6 

6. 0 

7.2 

2.4 

6.8 

6.4 

7.5 

2. 0 

3.5 

2.0 

1. 5 

1.6 

1.0 

2.3 

2.4 

1.7 

1.4 .26 

2.3 -.01 

1.3 .30 

. 7 . 73 

1. 0 .30 

.6 . 03 

1.6 .20 

Skewness 

I I ~ 

QD• Skq• Sk 

0. 33 o. 66 0. 40 

.44 

.31 

.22 

.62 

. 74 

.43 

.58 .99 .25 

-.16 -.11 1.17 

. 24 • 48 . 51 

. 37 . 66 . 40 

.26 .26 .69 

.06 .14 .83 

. 01 . 03 . 96 

.11 .20 . 76 

. 26 .36 . 61 

-. 13 -. 31 1. 53 

.20 .27 .68 

.58 .43 .55 

. 16 .16 . 81 

-.04 -.02 1.02 

.14 . 22 . 74 

Finer 

than 3 micron 

(percent) 

23 

48 

9 

22 

45 

18 

8 

24 

18 

61 

57 

12 

67 

41 

67 

40 

47 

32 

37 

32 

24 

26 

3 

19 

8 

34 
C52 MECHANICS OF AQUIFER SYSTEMS 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area-Continued 

Depth 

below 

Percentiles (mic;ons) Means 

Sample land 

surface 

I I I I I I I M, I QM, 

(feet) 1 5 16 25 50 75 84 95 (C) (Md) 

Mendota core-Continued 

57 CAL 26 ______ 743 180 71 40 29 13 4.3 1.8 ------ 6.9 6. 5 2. 5 4.6 5.1 6.3 7.9 9.1 57 CAL 27 ______ 757 430 340 200 140 62 15 6. 5 ------ 4.8 4.4 1.2 2.3 2.8 4.0 6.1 7.3 57 CAL 28 ______ 765 1, 200 750 550 490 320 86 25 ------ 3.1 2.3 -0.26 0.86 1.0 1.6 3. 5 5.3 57 CAL 29 ______ 773 110 93 80 73 51 15 5.8 ------ 5.5 4.9 3.2 3.6 3.8 4.3 6.1 7.4 57 CAL 30 ______ 785 110 90 62 45 20 5.2 1.9 -----·- 6.5 6. 0 3.2 4. 0 4.5 5.6 7.6 9. 0 57 CAL 3L _____ 791 210 130 82 63 26 1.8 -------- ------ -- .... ---- 6.6 2.3 4. 0 5.3 9.1 57 CAL 32 ______ 802 200 140 91 75 40 6. 0 1.9 ------ 6.2 5.6 2.3 3.5 3. 7 4.6 7. 4 9. 0 57 CAL 33 ______ 812 1, 500 1, 000 630 480 250 85 45 ------ 2.6 2.3 -0.58 0.67 1.1 2. 0 3.6 4. 5 57 CAL 34 ______ 813 1,100 510 330 280 210 170 150 ------ 2.2 2.2 -0.13 1.6 1.8 2.3 2.6 2. 7 57 CAL 35 ______ 826 65 23 13 8.8 3.3 1.2 ....................... ------ -------- 8.3 3.9 6.8 8.2 9. 7 57 CAL 36 ______ 832 200 110 53 42 20 3.5 1.1 ------ 7.0 6.4 2.3 4. 2 4.6 5.6 8.2 9.8 57 CAL37 ______ 844 230 180 150 140 110 37 14 ------ 4. 4 3.8 2.1 2. 7 2.8 3.2 4.8 6.2 57 CAL38 ______ 853 350 250 170 150 110 87 59 1. 7 3.3 3.1 1.5 2.6 2. 7 3.2 3. 5 4.1 57 CAL39 ______ 860 76 55 37 29 14 3.2 1.1 ------ 7.3 6. 7 3. 7 4.8 5.2 6.2 8.3 9.8 57 CAL 40 ______ 867 350 260 180 140 77 10 2.2 ------ 5.6 4. 7 1. 5 2.5 2.8 3. 7 6.6 8.8 57 CAL 4L _____ 871 640 300 180 150 98 50 22 ------ 4.0 3.5 0.64 2.5 2. 7 3.4 4.3 5.5 57 CAL 42 ______ 877 120 63 29 18 5.0 1. 0 -------- ------ -------- 7. 9 3.1 5.8 7.6 10.0 57 CAL 43 ______ 888 54 22 12 9.0 4.1 0.9 -------- ------ -------- 8. 5 4.2 6.8 7.9 10.1 57 CAL 44 ______ 901 200 90 38 25 11 2.9 1.6 ------ 7.0 6.9 2.3 4. 7 5.3 6. 5 8.4 9.3 57 CAL 45 ______ 912 450 320 200 150 56 13 2. 5 ------ 5.5 4.5 1. 2 2.3 2. 7 4.2 6.3 8.6 57 CAL 46 ______ 917 500 350 280 250 210 100 39 ------ 3.3 2. 7 1. 0 1.8 2. 0 2.3 3.3 4.7 57 CAL 47------ 932 330 80 40 27 6.4 -------- -------- ------ -------- -------- 1. 6 7.3 57 CAL 48 ______ 937 160 100 50 33 16 4. 9 2.3 ------ 6.5 6.3 2.6 4.3 4.9 6. 0 7. 7 8.8 57 CAL 49 ______ 951 210 58 35 25 8.2 1. 0 -------- ------ -------- 7.6 2.3 5.3 6.9 10.0 57 CAL 50 ______ 958 250 180 120 89 44 16 6. 7 ------ 5.1 4.7 2. c 3.1 3. 5 4.5 6. 0 7.2 57 CAL 5L _____ 969 17C 70 39 31 16 3.9 1. 0 ------ 7.3 6.5 2.f 4. 7 5. 0 6. 0 8. 0 10.0 57 CAL 52 ______ 984 150 27 7.3 4. 0 1. 5 -------- -------- ------ -------· -------- 2. 7 9.4 57 CAL 53 ______ 988 390 280 150 84 25 1.8 -------- ---- -- --------- 6.3 1.4 3.6 5.3 9.1 57 CAL 54 ______ 1, 001 240 60 27 19 6.8 1. 0 ------- ------ -------- 7.8 2.1 5. 7 7.2 10.0 57 CAL 55 ______ 1, 005 140 39 25 20 8.9 2.5 -·------ ------ -·------ 7.1 2.8 5.6 6.8 8.6 57 CAL 56 ______ 1, 021 200 89 52 40 23 5. 0 1.9 ------ 6. 7 6.1 2.3 4.3 4.6 5. 4 7.6 9.0 57 CAL 57 ______ 1, 034 750 500 350 260 71 14 4. 0 ------ 4. 7 4. 0 0.41 1.5 1. 9 3.8 6.2 8. 0 57 CAL 58 ______ 1, 040 170 29 17 12 4.9 -----~ -- -------- ------ ----............ ------ -- 2.6 7. 7 57 CAL 59 ______ 1, 051 140 84 55 44 25 7.1 2.2 ------ 6. 5 5.8 2.8 4.2 4.5 5.3 7.1 8.8 57 CAL 60 ______ 1, 064 400 300 230 170 26 4.5 0.9 ------ 6.1 5.2 1.3 2.1 2.6 5.3 7.8 10.1 57 CAL 61__ ____ 1, 071 310 180 81 47 20 3.6 1.0 ------ 6.8 6.3 1.7 3.6 4.4 5.6 8.1 10.0 57 CAL 62 ______ 1, 075 400 300 200 160 79 17 3. 0 ------ 5.3 4.3 1.3 2.3 2.6 3. 7 5.9 8.4 57 CAL 63 ______ 1, 089 480 360 280 250 1RO 90 51 ------ 3.1 2. 7 1.1 1.8 2. 0 2.5 3. 5 4.3 57 CAL 64 ______ 1, 092 1,100 730 370 150 42 15 4.8 ------ 4.6 4. 4 -0.13 1.4 2. 7 4.fl 6.) 7. 7 57 CAL 65------ 1,105 1,200 750 270 120 37 9.4 2.4 ------ 5.3 4. 9 -0.26 1.9 3.1 4.8 6. 7 8. 7 57 CAL 66------ 1,114 440 360 290 270 230 180 130 ------ 2.4 2. 2 1.2 1.8 1.9 2.1 2.5 2.9 57 CAL 67 ______ 1,124 450 340 250 220 160 110 65 ------ 3.0 2. 7 1.2 2. 0 2. 2 2.6 3.2 3. 9 57 CAL 68------ 1,133 110 66 33 23 10 2.3 -------- ------ -------- 7.1 3.2 5.4 6.6 8.8 57 CAL 69 ______ 1,160 3,800 870 440 350 250 150 78 ------ 2.4 2.1 -1.9 1.2 1.5 2.0 2. 7 3. 7 57 CAL 70-- --- 1,174 7,500 1,900 950 750 520 270 140 ------ 1. 5 1.1 -2.9 .07 .41 .94 1.9 2.8 57 CAL 71 ______ 1,207 25,500 16,000 6, 700 2,600 520 240 120 1.3 . 2 .3 -4.7 -2.7 -1.4 .94 2.1 3.1 

Deviations 

(I'~ I QD, a~ 

I 

2.2 1.4 0. 27 

2. 5 1.6 .32 

2.2 1.3 . 65 

1.9 1.1 .66 

2. 5 1.6 .35 

-------- 2.6 --------

2.8 1.8 .58 

1.9 1.2 .30 

.6 .4 -.14 

-------- 1.4 --------

2.8 1. 8 .50 

1.7 1.0 • 74 

.8 . 4 .18 

2. 5 1.6 .45 

3.2 1. 9 .61 

1.5 .8 .42 

-------- 2.1 --------

-------- 1. 7 --------

2.3 1. 6 .21 

3.2 1. 8 .42 

1.4 .7 .71 

-------- -------- --------

2.2 1.4 .26 

-------- 2.3 --------

2.1 1. 2 .30 

2.6 1. 5 .51 

-------- -------- ~ -------

-------- 2.8 --------

-------- 2.1 --------

-------- 1.5 --------

2. 4 1.5 . 51 

3.2 2.1 .28 

-------- -------- --------

2.3 1.3 . 51 

4. 0 2.6 . 21 

3.2 1.9 .37 

3. 0 1.6 .56 

1.2 0.7 .48 

3.1 1.7 .00 

3.4 1.8 .16 

0.6 .3 .42 

1.0 . 5 .34 

-------- 1. 7 --------

1. 2 .6 .34 

1.4 . 7 .37 

2.9 1. 7 -.27 

Skewness 

I 

Skq~ 

QD~ Skq~ 

0.15 0. 21 

.27 . 44 

. 51 . 64 

. 55 .63 

.25 .39 

. 50 1.28 

. 51 .92 

.25 .31 

-.14 -.05 

.01 .02 

.40 . 72 

.65 .62 

-.13 -.05 

.36 .56 

.55 1. 04 

.23 .18 

.12 .24 

.32 .53 

.23 .36 

.19 .34 

.62 .41 

---------- --------

.23 .32 

• 31 .71 

.18 .22 

.36 .53 

---·------ ................... a 

.37 1.02 

.30 .64 

. 22 .33 

.47 • 70 

.11 .23 

---------- --------

.38 . 50 

-.03 -.09 

.33 .62 

.37 .60 

.36 . 26 

-.10 -.17 

. 07 .13 

.21 .06 

.08 .04 

.28 .46 

.20 .12 

.28 .21 

-.35 -.60 

I 

Sk 

0. 74 

. 55 

. 41 

.42 

.58 

.15 

.28 

.65 

1.08 

.97 

. 37 

.43 

1.08 

.46 

.24 

. 78 

• 72 

.48 

.60 

.62 

.57 

--------

.63 

.37 

• 74 

.47 

--------

0.24 

.41 

.63 

. 38 

. 72 

--------

.50 

1.13 

.42 

.44 

.69 

1.28 

.82 

.92 

.95 

.53 

.84 

. 75 

2.31 

Finer 

thana 

micron 

(percent) 

2 

1 

1 

1 

0 

8 

3 

9 

1 

28 

9 

8 

7 

2 

48 

4 

0 

6 

1 

24 

7 

0 

1 

1 

4 

44 

26 

6 1 

4 

1 9 

7 

2 

3 

1 

23 

68 

28 

3 6 

7 

0 

5 

2 

2 

1 

41 

1 

2 

8 

2 

4 

6 

9 

4 

7 

7 

2 

1 

1 

1 

28 

8 

7 

7 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C53 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area-Continued 

Depth Percentiles (mic;ons) Means Deviations 

below 

Sample land 

surface 

I I I I I I I M,l QM, I QD, 

(feet) 1 5 16 25 50 75 84 95 

(C) (Md) IT!f> 

Mendota core-Continued 

57 CAL 7Z_. _____ 1,219 6,600 1,400 460 360 250 110 24 ------ 3.2 2.3 2.1 0.9 -2.7 1.1 1.5 2. 0 3.2 5. 4 57 CAL 73 ______ 1,221 4,100 2,200 1,100 770 350 130 7.4 ------ 3.5 1. 7 3.6 1.3 -2.0 -.13 .38 1.5 2.9 7.1 57 CAL 7L ____ 1,232 6,300 2,900 1,400 770 370 190 100 5.1 1.4 1. 4 1.9 1. 0 -2.7 -.49 .38 1. 4 2. 4 3.3 57 CAL 7~------ 1,242 150 100 58 40 20 7.2 3.1 ------ 6.2 5. 9 2.1 1.2 2. 7 4.1 4.6 5.6 7.1 8.3 57 CAL 76 ______ 1, 252 400 300 210 170 130 56 18 ------ 4.0 3. 4 1.8 .8 1. 3 2.3 2.6 2.9 4. 2 5.8 57 CAL 77 ______ 1,257 860 600 350 250 160 73 16 ------ 3. 7 2. 9 2. 2 .9 .22 1.5 2.0 2.6 3.8 6. 0 57 CAL 78 ______ 1, 270 1,100 600 310 220 82 5. 4 -------- ------ -------- 4.9 -------- 2. 7 -.13 2.2 3.6 7. 5 57 CAL 79 ______ 1, 271 440 350 270 240 180 30 3.6 ------ 5.0 3.6 3.1 1.5 1.2 1.9 2.1 2. 5 5.1 8.1 57 CAL 80 ______ 1, 284 410 310 240 210 170 130 85 ------ 2.8 2.6 .7 . 3 1. 3 2.1 2. 3 2.6 2.9 3.6 57 CAL SL ____ 1, 293 410 320 220 180 81 8. 3 1. 0 ------ 6.1 4. 7 3.9 2.2 1.3 2.--2 2. 5" 3.6 6:9 10.0 57 CAL 82 ______ 1,300 400 320 240 210 120 11 1. 3 ------ 5.8 4.4 3.8 2.1 1. 3 2.1 2.3 3.1 6. 5 9.6 57 CAL 83 ______ 1,312 460 310 170 65 22 3. 7 1.0 ------ 6.3 6.0 3. 7 2.1 1.1 2.6 3.9 5.5 8.1 10.0 57 CAL 84 ______ 1,320 440 340 270 240 170 14 2. 5 ------ 5.3 4.1 3.4 2.0 1.2 1.9 2.1 2.6 6. 2 8. 6 57 CAL 85 ______ 1,331 430 280 230 190 130 13 1.2 ------ 5.9 4.3 3.8 1.9 1.2 2.1 2. 4 2.9 6.3 9. 7 57 CAL 86 ______ 1,340 220 120 67 48 22 5. 5 2.0 ------ 6.4 5.9 2. 5 1. 8 2. 2 3.9 4.4 5. 5 7. 5 9.0 57 CAL 87 ______ 1,348 8,800 4,300 1,000 780 480 220 130 ------ 1. 5 1.3 1. 5 ·' -3.1 0.0 0. 36 1.1 2. 2 2. 9 57 CAL 88 ______ 1,357 180 96 33 20 5.8 1. 2 -------- ------ -------- 7. 7 -------- 2.0 2. 5 5.6 7.4 9. 7 57 CAL 89 ______ 1,363 250 150 95 70 30 5. 2 -------- ------ -------- 5. 7 -------- 1. 9 2.0 3. 8 5.1 7.6 57 CAL 90 ______ 1,374 360 260 190 160 64 6. 9 1.4 ------ 5.9 4.9 3.5 2.3 1. 5 2.4 2.6 4.0 7. 2 9. 5 57 CAL 91__ ____ 1,385 360 230 100 45 16 4. 2 1.9 ------ 6. 2 6. 2 2.9 1."7 1. 5 3.3 4. 5 6.0 7. 9 9.0 57 CAL 92 ______ 1,397 450 290 29 8. 7 2.3 -------- -------- ------ -------- -------- -------- -------- 1.2 8.8 57 CAL 93 ______ 1,406 420 330 250 210 110 9.0 2.1 ------ 5.4 4. 5 3.4 2.3 :.. 3 2.0 2.3 3. 2 6.8 8.9 57 CAL 94 ______ 1, 415 530 380 260 200 91 21 4.6 ------ 4.8 3.9 2.9 1.6 0.92 1.9 2.3 3.5 5.6 7.8 57 CAL 95 ______ 1, 424 390 240 160 130 85 20 5.0 ------ 5.1 4. 3 2. 5 1.3 1.4 2.6 2.9 3.6 5.6 7.6 57 CAL 96 ______ 1,433 94 55 30 22 9.0 1. 7 -------- ------ -------- 7.4 -------- 1.8 3.4 5. 5 6.8 9. 2 57 CAL 97 ______ 1. 446 50 33 18 12 4. ~ -------- -------- ------ -------- -------- -------- -------- 4.3 7. 7 57 CAL 98 ______ 1, 455 350 220 120 73 20 4. 2 1. 4 ------ 6.3 5.8 3. 2 2.1 1. 5 3.1 3.8 5.6 7.9 9. 5 57 CAL 99 ______ 1,465 280 35 11 6.8 2.3 -------- -------- ------ -------- ---------------- -------- 1.8 8.8 57 CAL 100 _____ 1,474 410 250 180 160 120 48 26 ------ 3. 9 3. 5 1.4 .9 1.3 2. 5 2.6 3.1 4.4 5. 3 57 CAL 101__ ___ 1,481 2, 500 800 410 270 74 13 4.3 ------ 4.6 4.1 3.3 2. 2 -1.3 1.3 1.9 3.8 6.3 7. 9 57 CAL 102 _____ 1,487 580 420 340 300 220 130 39 ------ 3.1 2. 3 1.6 .6 0. 79 1. 6 1.7 2. 2 2. 9 4. 7 57 CAL 103 _____ 1,495 430 280 210 180 87 14 5.9 ----- 4.8 4.3 2.6 1. 8 1. 2 2. 3 2.5 3.5 6. 2 7.4 

Cantua Creek core 

58 CAL L _____ 250 3,800 950 340 250 120 41 11 ------ 4.0 3.3 2. 5 1. 3 -1.9 1. 6 2.0 3.1 4.6 6. 5 58 CAL 2__ _____ 298 520 220 92 57 17 3.0 -------- ------ -------- 6.3 2.1 0.94 4.1 5.9 8.4 58 CAL 3 _______ 333 500 290 140 70 10 1.5 -------- ------ -------- 6.6 2.8 1.0 3.8 6.6 9.4 58 CAL 4__ _____ 372 740 510 370 310 140 52 8. 7 4.1 3.0 2. 7 1.3 0.43 1.4 1.7 2.8 4. 3 6.8 58 CAL 5 _______ 419 240 130 61 37 8. 5 2.3 1.4 6.8 6.8 2. 7 2.0 2.1 4. 0 4. 8 6. 9 8.8 9. 5 58 CAL 6 _______ 455 330 130 71 42 5.0 -------- -------- ------ -------- -------- ------- 1.6 7.6 58 CAL 7 ___ --- 497 700 370 260 230 150 49 14 ------ 4.0 3. 2 2.1 1.1 0. 51 1. 9 2.1 2. 7 4.4 6. 2 58 CAL 8 _______ 508 2, 200 170 38 22 7. 5 1.5 -------- ------ -------- 7.4 1.9 -1.1 5. 5 7.1 9.4 58 CAL 9 _______ 510 110 60 32 22 9. 7 3.3 -----·-- ------ -------- 6.9 1.4 3. 2 5. 5 6. 7 8.2 58 CAL 10. _____ 526 100 38 16 11 5. 7 1.8 ------·- ---·-- -------- 7.8 1.3 3.3 6. 5 7. 5 9.1 58 CAL ll ______ 533 580 360 210 140 28 2. 3 -------- ------ -------- 5.8 3.0 0. 79 2.8 5. 2 8.8 58 CAL 12 ______ 553 300 170 78 47 16 2.3 1. 3 6.6 6.6 3.0 2. 2 1. 7 3. 7 4.4 6.0 8.8 9.6 

Skewness 

I I 

Skq• a• QD"' Skq"' 

0.59 0.38 0.32 

.54 .12 .15 

-.01 -.04 -.04 

.Zl .19 . 24 

. 61 . 52 .42 

.49 .28 . 25 

-------- .46 1. 24 

.81 . 73 1.09 

.33 .09 .03 

.63 .48 1.06 

. 73 .62 1. 32 

.20 .24 .50 

.80 . 76 1. 55 

. 78 . 72 1. 39 

.36 .28 .43 

.28 .23 . 21 

-------- .12 .24 

-------- .35 .65 

.56 .41 .94 

.07 .12 . 21 

-------- ---------- --------

.flt'l .59 1.34 

.48 .30 •• 8 

:-63 .54 ·" -------- .30 . 55 

-------- ---------- ·-------

.20 .10 .20 

-------- ---------- --------

.58 . 52 .45 

. 25 .15 .32 

.60 .27 .16 

. 51 .43 . 79 

0.39 0.18 0. 24 

.17 .37 

-.01 -.03 

.48 .11 .14 

-.04 -.06 -.12 

--------- ---- ----- --------

. 62 .44 .49 

. 20 .38 

.13 .18 

.28 .36 

• 2'2 .64 

. 22 .28 . 61 

I 

Sk 

0.63 

.82 

1. 07 

. 72 

. 56 

.71 

.18 

• 22 

.95 

.23 

.16 

.50 

.12 

.15 

.55 

. 75 

.71 

.40 

.27 

• 74 

--------

.16 

. 51 

.36 

.46 

--------

. 77 

--------

.53 

.64 

. 81 

.33 

0. il 

. 59 

1. 05 

.82 

1.18 

--------

.50 

.59 

.77 

.61 

.41 

.42 

Finer 

than 3 microns 

(percent) 

1 

9 

3 

1 6 

8 

1 

2 

1 

8 

20 

20 

23 

1 

1 

1 

6 

8 

9 

2 

1 9 

2 

1 

1 

1 

56 

8 

s 

4 

3 

40 

2 2 

1 

1 

1 

56 

0 

3 

8 

2 

12 

25 

32 

13 

31 

46 

13 

34 

24 

34 

27 

28 
054 MECHANICS OF AQUIFER SYSTEMS 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman C1'ty area-Continued 

Depth 

below 

Sample land 

surface 

(feet) 

58 CAL 13______ 564 

58 CAL 1L.___ 571 

58 CAL 15------ 581 

58 CAL 16______ 592 

58 CAL 17______ 602 

58 CAL 18______ 623 

58 CAL 19______ 637 

58 CAL 20______ 643 

58 CAL 2L____ 653 

58 CAL 22______ 666 

58 CAL 23______ 674 

58 CAL 2L____ 684 

58 CAL 25______ 697 

58 CAL 26______ 702 

58 CAL 27______ 714 

58 CAL 28______ 722 

58 CAL 29______ ·· 732 

58 CAL 30______ 746 

58 CAL 3L_____ 754 

58CAL32______ 763 

58CAL33______ 774 

58 CAL 34______ 785 

58 CAL 35 ______ · 795 

58 CAL 36______ 806 

58 CAL 37______ 811 

58 CAL 38______ 822 

58 CAL 39______ 828 

58 CAL 40______ 838 

58 CAL 41______ 852 

58 CAL 42______ 860 

58 CAL 43______ 867 

58 CAL 44______ 877 

58 CAL 45-.---- 892 

58 CAL 46______ 901 

58 CAL 47______ 911 

58 CAL 48______ 923 

58 CAL 49______ 931 

58 CAL 50_______ 941 

58 CAL 51_______ 947 

58 CAL 52_______ 964 

."J8 CAL 53_______ 972 

58 CAL 54_______ 981 

58 CAL 55_______ 999 

58 CAL 56_______ 1,012 

58 CAL 57_______ 1, 037 

1 

(C) 

310 

1.7 

350 

1.5 

480 

1.1 

800 

0.32 

780 

.36 

790 

.34 

400 

1.3 

370 

1.4 

630 

.67 

200 

2.3 

290 

1.8 

170 

2.6 

160 

2.6 

260 

1.9 

200 

2.3 

430 

1.2 

320 

1.6 

310 

1.7 

190 

2.4 

320 

1.6 

340 

1.6 

450 

1.2 

210 

2.3 

-· 190 

2.4 

290 

1.8 

600 

o. 74 

350 

1.5 

150 

2. 7 420 

1.3 

330 

1.6 

340 

1.6 

450 

1.2 

340 

1.6 

220 

2. 2 430 

1.2 

250 

2. 0 

370 

1.4 

150 

2. 7 

60 

4.1 

320 

1.6 

96 

3. 4 160 

2. 6 1, 300 -0.38 

1,100 

-0.13 280 

1.8 

I 

5 

140 

83 

360 

510 

590 

460 

220 

200 

360 

52 

u 

110 

38 

100 

58 

260 

180 

130 

86 

200 

220 

360 

110 

83 

190 

260 

240 

59 

340 

200 

220 

390 

200 

82 

280 

120 

240 

97 

21 

180 

47 

97 

880 

710 

61 

I 

Percentiles 

16 

63 

4.0 

38 

280 

1.8 

370 

1.4 

450 

1. 2 

310 

1.7 

97 

3.4 

100 

3.3 

200 

2.3 

13 

8.1 

70 

3.8 

12 

49 

.23 

5.4 

170 

2.6 

86 

30 

37 

4.8 

81 

130 

2.9 

290 

1.8 

28 

22 

110 

3.2 

98 

120 

21 

220 

2. 2 

100 

150 

310 

1.7 

81 

25 

220 

2. 2 

46 

100 

50 

9. 1 

100 

3. 3 

26 

5.3 

68 

3. 9 

700 

0. 51 

440 

1. 2 

26 

I 

25 

38 

4. 7 

23 

5.4 

260 

1.9 

330 

1.6 

390 

1.4 

260 

1.9 

63 

4.0 

73 

3.8 

140 

2.8 

8.8 

6.8 

4. 7 

56 

4.2 

7. 0 

34 

4. 9 

H 

6.2 

120 

3.1 

55 

4.2 

11 

25 

5.3 

34 

4. 9 

95 

3. 4 250 

2. 0 

13 

10 

78 

3. 7 

43 

70 

11 

6. 5 160 

2.6 

64 

4. 0 

120 

3.1 

270 

1.9 

40 

13 

200 

2.3 

22 

60 

4.1 

30 

5.9 

71 

3.8 

19 

5. 7 

57 

4.1 

620 

0.69 

340 

1.6 

15 

6.1 

(mic;ons) 

I 

50 

(Md) 

9.3 

6. 7 

5.5 

7.5 

200 

2.3 

270 

1.\1 

300 

1. 7 

180 

2.5 

21 

5.6 

29 

5.1 

37 

4.8 

4.4 

7.8 

1. 5 9.4 

30 

5.1 

2.0 

9.0 

15 

6.1 

5. 0 

7.6 

55 

4.2 

21 

5.6 

1.2 

9. 7 

12 

6.4 

5.1 

7.6 

33 

4. 9 180 

2. 5 

2.1 

8.9 

2.9 

8.4 

41 

4.6 

3. 2 8.3 

8. 2 6.9 

3.6 

8.1 

64 

4. 0 

16 

6. 0 

70 

3.8 

190 

2.4 

5.4 

7. 5 3. 0 8. 4 

130 

2.9 

4.1 

7.9 

15 

6.1 

6.3 

7.3 

2.1 

8.9 

28 

5. 2 

8. 7 6. 8 

38 

4. 7 440 

1.2 

210 

2.3 

3.8 

8.0 

I 

Means Deviations 

I I A4 I QA4 I QD, 

75 84 95 ,. a• 

Cantua Creek core-Continued 

2.0 

9.0 

1.0 

10.0 

140 

2.8 

210 

2.3 

230 

2.1 

99 

3.3 

4.4 

7.8 

6.5 

7.3 

3.4 

8.2 

0.9 

10.1 

5. 7 7.5 

3.0 

8.4 

2.0 

9.0 

12 

6. 4 5.3 

7.6 

2. 4 

8. 7 1.0 

10.0 

4.3 

7. 9 

100 

3.3 

10 

6.6 

0.9 

10.1 

6.6 

7.2 

2.9 

8.4 

4.2 

7.9 

88 

3. 5 

57 

4.1 

1. 0 ------ 7. 0 10.0 

97 27 2.6 3.4 

190 120 1. 9 2.4 

180 46 1.8 2.5 

65 4.3 2.8 3.9 

2.0 6. 2 9.0 

1.2 6.5 9. 7 1.0 6.1 10.0 

1. 0 ------ 10.0 

1.4 

9. 5 

1.0 

10.0 

6.9 

7. 5 

6.3 

1. 0 ------ 7. 4 10.0 

1.0 

10.0 

57 

4.1 

2. 2 ------ 8.8 

6. 5 

3. 0 

6. 0 

1. 2 ------ 5. 9 9. 7 

32 ------ 3.3 5. 0 

30 ------ 5.1 

3.6 

2. 0 -------- ------ -------- 9.0 

5. 7 

7. 5 2. 2 8. 8 

18 

5.8 

280 

1.8 

130 

2.9 

1.2 

9. 7 

1. 7 6. 3 9. 2 

1. 0 7. 6 10.0 11 1. 4 5. 2 6. 5 210 81 1. 4 2. 3 

91 18 2. 3 3. 5 

6.8 

7. 7 

2.4 

1.9 

1.7 

2.6 

5.9 

5.5 

5.5 

8.5 

5.8 

6.6 

7.6 

4. 7 

5.9 

7.0 

7. 4 

5.6 

2. 7 

5. 2 

8.3 

4. 9 

6. 2 

5. 5 

2. 7 

3. 2 

3.0 

.8 

. 5 

. 7 

1.1 

2.8 

3.2 

3.8 

3.1 

2. 0 

3. 7 

2.6 

3.5 

1.2 

2.8 

3.8 

1.6 

1.4 

6. 5 --------

5.6 

7. 3 

5.0 

1.3 

2. 2 

7.9 

2.9 

2.3 

1.3 

.9 

1.1 

2.1 

2.3 

.4 

.3 

.4 

.7 

1.9 

1.7 

2. 7 

1.6 

1. 6 

1.7 

1.4 

1.7 

1.7 

1.7 

2.5 

2. 2 

. 7 

1.5 

1.8 

2.3 

2. 2 

2. 4 

.8 

.9 

0.08 

.37 

.04 

.11 

.30 

• 21 

.44 

.36 

.60 

-.09 

.56 

.38 

.44 

. 42 

. 49 

. 52 

. 57 

. 47 

2. 5 --------

1.8 

1. 6 

.8 

.6 

. 7 

1.8 

.37 

.33 

.36 

.23 

.06 

I 

Skewness 

Skq• 

QD• 

0.04 

.08 

.16 

.09 

.00 

.24 

.18 

.24 

.28 

.39 

.45 

.33 

-.06 

.33 

.18 

.37 

-.08 

.32 

.29 

.37 

.11 

. 42 

.10 

.68 

. 37 

. 31 

.19 

.26 

.28 

.29 

.14 

.00 

-.09 

I 

Skq• 

0.09 

.19 

.07 

.03 

.00 

.17 

.34 

.41 

. 76 

.64 

. 75 

. 57 

-.08 

.54 

.30 

.63 

-.20 

.71 

.19 

. 55 

.19 

. 97 

. 23 

1. 64 

.30 

.28 

.45 

.47 

.43 

. 24 

.08 

.00 

-.16 

I 

Sk 

0.88 

. 76 

.91 

.95 

1.00 

• 79 

.63 

.56 

.35 

.41 

.35 

. 45 

1.12 

.48 

.66 

. 42 

1. 31 

.38 

. 77 

.46 

. 76 

.26 

. 72 

.10 

.66 

. 67 

.53 

. 52 

. 55 

.71 

.90 

1.00 

1. 25 

Finer 

thana 

micro ns (percent) 

31 

40 

3 

0 

4 

21 

20 

24 

42 

65 

21 

58 

25 

37 

17 

24 

58 

27 

42 

21 

55 

51 

17 

49 

39 

46 

21 

25 

24 

9 

44 

50 

11 

45 

29 

41 

59 

20 

29 

8 

0 

3 

45 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFQRNIA C55 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area-Continued 

Sample 

Depth 

below 

land 

surface 

(feet) 

58 CAL 58....... 1, 04a 

58 CAL 59....... 1, IM 

58 CAL 60....... 1, 181 

58 CAL 61.._____ 1, 190 

58CAL62 ______ 1,203 

58 CAL 63_ _____ 1, 225 

58 CALM ______ 1,238 

58 CAL 65_____ _ 1, 241 

58 CAL66 ______ 1,255 

58CAL6L ____ 1,280 

58CAL68 ______ I,a26 

58 CAL 69_ _____ 1,332 

58 CAL 70______ I,a52 

58CAL7L ____ I,aM 

58CAL72 ______ l,a72 

58 CAL 7a____ _ _ 1, 392 

58 CAL 74______ 1,402 

58 CAL 75______ 1,414 

58 CAL 76______ 1,422 

58 CAL 77______ 1,4a2 

58 CAL 78______ 1,459 

58 CAL 79______ 1, 476 

58 CAL 80______ 1,4sa 

58 CAL 8L____ 1,496 

58 CAL 82______ 1, 507 

58 CAL sa______ 1, 507 

58 CAL 8L____ 1, 526 

58 CAL 85______ 1, 551 

58 CAL 86______ 1,558 

58 CAL 87______ 1,566 

58 CAL 88______ 1,590 

58 CAL 89______ 1,631 

58 CAL 90______ 1, 677 

58 CAL 91______ 1, 714 

58 CAL 92______ 1, 752 

38 CAL 93______ 1, 793 

58 CAL 94______ 1,838 

58 CAL 95______ 1, 872 

58 CAL 96______ 1, 917 

58 CAL 97______ 1,953 

58 CAL 98______ 1,990 

57 CAL 104 _____ 1 

57 CAL 105 ••••• .: I 

320 

1. 6 410 

1. a 430 

1.2 

140 

2.8 

400 

1.3 

190 

2.4 

210 

2.2 

220 

2.2 

180 

2.5 

100 

a.3 

290 

1. 8 a 50 

1.5 

a 50 

1. 5 

280 

1.8 

480 

1.1 

260 

1.9 

450 

1.1 

1,600 

-.68 

450 

1.1 

570 

.81 

2a 

5.4 

120 

a.1 

100 

3.a 

480 

1.1 

aoo 

1.5 

460 

1.1 

a90 

1.4 

870 

.20 1aO 

2.9 

690 

.M 

55 

4.2 

160 

2.6 

260 

1. 9 

400 

1.3 

640 

0.64 

380 

1. 4 

180 

2.5 

58 

4.1 

76 

a. 1 

240 

2.1 

1, 700 

-.77 

430 ~I 1.2 

97 

200 

270 

87 

270 

98 

48 

tao 

61 

52 

140 

220 

160 

220 

260 

200 

a7o 

800 

340 

330 

13 

75 

58 

380 

250 

260 

180 

610 

55 

400 

30 

68 

160 

270 

310 

260 

140 

40 

36 

190 

1.aoo 

Percentiles ( mic;ons) Means Deviations Skewness 

75 84 

Finer 

than a ---~---.,...------,----microns 

I ~ M, F~F .. I ~: I Skq·l Sk ~i 

a1 

96 

a.4 

110 

52 

110 

M 

4.2 

22 

5.;; 

sa 

a.6 

34 

4.9 

37 

4.8 

26 

150 

2. 7 

84 

3.6 

180 

2.5 

130 

2.9 

150 

2. 7 

290 

1.8 

aao 

200 

2.3 

57 

7.4 

42 

38 

4. 7 

240 

2.1 

180 

2.5 

150 

48 

420 

1.3 

19 

210 

13 

22 

81 

120 

160 

160 

2.6 

100 

3.3 

24 

5.4 

20 

130 

740 

131 

170 

16 

62 

4.0 

34 

39 

4. 7 

44 

41 

4.6 

16 

6.0 

68 

3.9 

26 

5.3 

31 

5.0 

15 

6.1 

130 

2.9 

63 

4.0 

160 

2.6 

95 

3.4 

110 

3.2 

240 

2.1 

190 

2.4 

140 

2.8 

23 

5.4 

5.4 

7.5 

29 

5.1 

29 

5.1 

160 

2.6 

140 

2.8 

100 

3.3 

30 

5.1 

350 

1.5 

9. 7 6. 7 

150 

2. 7 8.0 

7.0 

11 

6.5 

52 

4.3 

77 

3. 7 

98 

120 

3.1 

88 

3.5 

18 

5.8 

14 

6.2 

75 

460 

1.1 

8.1 I 100 

3.3 

3. 2 8.3 

20 

5.6 

1. 6 9. 3 

17 

5.9 

2.8 

8.5 

23 

5.4 

6. 7 7.2 

44 

4.5 

15 

6.1 

15 

6.1 

4.4 

7.8 

99 

3.3 

30 

5.1 

110 

3.2 

56 

4.2 

38 

4. 7 

140 

2.8 

61 

4.0 

65 

3.9 

4.9 

7.7 

2.6 

8.6 

8.6 

6.9 

12 

6.4 

51 

4.3 

59 

4.1 

14 

6. 2 

10 

6.6 

240 

2.1 

3.1 

8.3 

66 

3.9 

5.0 

7.6 

3. 7 8.1 

15 

6.1 

20 

5.6 

4.1 

7.9 

62 

4.0 

59 

4.1 

9.5 

6. 7 6.9 

7.2 

6.8 

7.2 

86 

3.5 

Cantua Creek cor~Continued 

5.1 

7.6 2. 4 ------ 8.7 6.0 

1. 7 -------- ------ -------- 9.2 

9.1 

6.8 

2.0 

9.0 

17 

5.9 

8.0 

7.0 

3.4 

8.2 

1.3 

9.6 

70 

3.8 

10 

6.6 

63 

4.0 

31 

5.0 

8. 7 6.8 

51 

4.3 

3.5 

8.2 

14 

6.2 

.9 

10.1 

1.3 

9.6 

1.5 

9.4 

3.0 

8.4 

12 

6.4 

16 

6.0 

1.0 

10.0 

2.3 

8.8 

160 

2.6 

1.3 

9.6 

13 

6.3 

2.6 

8.6 

1.3 

9.6 

1.1 

9.8 

1.4 

9.5 

4.4 6.0 7.8 

1. 0 7. 7 10.0 

8.8 5.2 6.8 

4.9 6.3 7. 7 1.6 7.0 9.3 

49 1. 0 3. 5 4.4 

1.8 6. 3 9.1 

46 18 3. 5 

4.4 

21 5.3 4.3 5.6 

4. 5 1.3 5.3 7.8 

23 3. 6 5.4 

3. 6 ------ 5. 2 8.1 

1.0 7.3 10.0 

1.5 5. 7 9.4 

3.8 5.3 8.0 

120 21 2. 2 3.1 

R5 2.3 ~7 

6. 7 8.8 18 6.5 5.3 5.8 7.3 &4 1.5 ~4 

8.2 9.4 

1.6 -------- ------ -------- 9.3 

1. 6 -------- ------ -------- 9.3 

Huron core 

5.8 2. 7 

6. 9 --------

5. 7 

7.5 

4.9 

6.1 

6.6 

7.8 

3.4 

5. 3 

3.a 

4.2 

5.0 

3. 2 

5.3 

4.5 

7. 8 

8.6 

7.2 

6. 7 

4.5 

4.4 

6.6 

6.9 

2.1 

8.1 

4.5 

7.8 

8.0 

7. 0 

6.6 

4.9 

4. 7 

7.0 

7. 7 

1.8 

2.2 

1.6 

1. 4 

2.3 

.8 

2.8 

1.0 

1.3 

2.5 

1.8 

2.9 

2.6 

3. 7 

2.8 

.9 

3.1 

2.0 

2.0 

5.2 --------

1.8 0.15 

2.3 ---------

1.1 

1.5 

1.0 

.8 

1.6 

1.8 

.4 

1.3 

.7 

.8 

1.8 

1.1 

2.9 

1.7 

2.3 

1.0 

2.1 

1.6 

1.9 

1.6 

3.3 

1.8 

. 6 

1.4 

1.8 

.8 

1. 5 

2.8 

2.9 

1.8 

1.1 

1.2 

1.6 

.32 

.23 

.4a 

.15 

.42 

.25 

.46 

.28 

.07 

. 22 

.42 

.44 

.37 

.39 

.42 

.10 

.55 

.61 

.aa 

4.1 ---- ---

0.09 

.47 

.23 

.17 

.37 

.07 

.34 

-.01 

.11 

.19 

.19 

.05 

.16 

.30 

.43 

.34 

.05 

-.03 

.18 

.22 

.12 

. 21 

.14 

.15 

.02 

-.13 

.33 

.17 

-.02 

.36 

.aa 

.48 

.50 

.23 

.35 

.41 

0.17 

1.06 

.25 

.25 

.37 

.06 

.54 

-.01 

.05 

. 25 

.13 

.04 

.29 

.33 

1. 24 

.56 

.11 

-.03 

.38 

.36 

. 22 

.32 

.48 

. 27 

.01 

-.19 

. 58 

.14 

-.03 

.99 

.95 

.88 

.57 

.28 

-M 

1. 66 

0. 79 

.23 

.71 

.71 

.60 

.92 

.47 

1. 01 

.93 

. 70 

.83 

.94 

.66 

.62 

.18 

. 46 

• 86 

1. 05 

. 57 

.60 

. 74 

.64 

. 51 

.69 

.97 

1. 31 

.45 

.sa 

1.04 

.25 

.27 

.30 

.46 

.68 

.47 

.10 

49 

19 

56 

29 

51 

13 

32 

10 

12 

23 

43 

6 

17 

2 

4 

11 

9 

24 

15 

42 

56 

32 

25 

18 

15 

34 

28 

3 

49 

18 

26 

43 

34 

30 

47 

17 

12 

23 

34 

42 

30 

53 

2i 
C56 MECHANICS OF AQUIFER SYSTEMS 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area-Continued 

Sample 

5 7 CAL 106__ ___ 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

7 CAL 107 _____ 

7 CAL 108 _____ 

7 CAL 109 _____ 

7 CAL 110 _____ 

7 CAL 111__ ___ 

7 CAL 112__ ___ 

7 CAL 113 _____ 

7 CAL IlL ___ 

7 CAL 115 _____ 

7 CAL 116 _____ 

7 CAL 117__ ___ 

7 CAL 118 _____ 

7 CAL 119 _____ 

7 CAL 120 ______ 

7 CAL 121. ____ 

7 CAL 122 _____ 

7 CAL 123 _____ 

7 CAL 124 _____ 

7 CAL I25 _____ 

7 CAL 126 _____ 

7 CAL 127 _____ 

7 CAL 128 _____ 

7 CAL 129 _____ 

7 CAL 130 _____ 

7 CAL 131. ____ 

7 CAL 132 _____ 

7 CAL 133 _____ 

7 CAL 1M _____ 

7 CAL 135 _____ 

7 CAL I36 _____ 

7 CAL 137 _____ 

5 7 CAL 138 _____ 

7 CAL 139 _____ 

5 7 CAL 1f0 _____ 

7 CAL 141__ ___ 

5 

5 

5 

7 CAL lf2__ ___ 

7 CAL 143 _____ 

7 CAL 14L ___ 

7 CAL 145 ____ 

7 CAL 146 ___ 

7 CAL 147 ____ 

57 CAL 148 _____ 

57 CAL 149 _____ 

57 CAL 150 _____ 

Depth 

below 

land 

surface 

(feet) 

234 

271 

310 

351 

400 

431 

f76 

510 

553 

5M 

631 

676 

713 

727 

732 

7f6 

767 

779 

789 

800 

810 

831 

861 

870 

870 

889 

906 

937 

M6 

948 

958 

972 

983 

994 

1,003 

1.028 

1,032 

1,042 

1,094 

1,105 

1,120 

1.132 

1,144 

1,145 

1,160 

I I 1 5 (C) 

380 240 1.-i 

380 120 I.f 

flj() 350 I.2 

260 89 

1.9 

450 390 1.2 

390 190 

I.f 

55 16 f.2 

380 280 l.f 

320 If() 1.6 

350 180 I.5 

350 230 I.5 

«O 350 1.2 

360 250 I.5 

240 200 2.1 

280 120 I.8 

f70 180 I.l 

880 650 O.IS 

250 120 2.0 

320 83 I.6 

160 37 2.6 

260 160 1.9 

260 160 1.9 

220 I20 2.2 

330 210 1.6 

no 24il I.3 

2IO 33 2.3 

flj() 320 I.l 

230 140 2.I 

210 f8 2.3 

290 120 1.8 

1,200 510 -0.26 300 150 1.7 

280 98 1.8 

310 180 1. 7 

450 MO 1.2 

220 84 2.2 

380 280 1.4 

460 360 1.1 

270 120 1.9 

310 140 1.7 

240 85 2.1 

420 280 1.3 

300 150 1.7 

320 160 1.6 

170 100 2.6 

Percentiles (mic;ons) Means 

I I I I I M, I QM, 

16 25 50 75 84 95 

(Md) 

Huron core-Continued 

130 97 f7 11 3.5 ------ 5.5 f.9 

2.9 3.-i ••• 6.5 8.2 15 6.8 2.0 -------- -------- ------ -------- -------- 9.0 210 If() 50 ... -------- ------ -------- 5.3 2.8 f.3 7.8 26 If 3.6 -------- -------- ------ -------- -------- 8.1 320 290 240 I 50 83 ------ 2.'6 2.3 I.6 1.8 2.I 2. 7 3.6 51 26 5.9 -------- -------- ................ -------- -------- 7.-i 8.8 6.5 3.2 I.O -------- ------ -------- 8.6 7.3 8.3 10.0 I90 I70 130 f8 10 ------ f.5 3.5 2.-i 2.6 2.9 ••• 6.6 50 30 10 2.-i -------- ------ -------- 6.9 5.I 6.6 8.7 130 IOO 58 29 13 ------ f.6 f.2 

2.9 3.3 f. I 5.1 6.3 I70 lfO 72 21 10 ------ f.6 f.2 2.6 2.8 3.8 5.6 6.6 290 260 200 130 100 1.5 2.6 2.-i I.S 1.9 2.3 2.9 3.3 190 I70 150 110 75 ------ 3.1 2.9 

2.-i 2.6 2. 7 3.2 3. 7 160 If() 100 M M ------ 3.8 3.-i 2.6 2.8 3.3 f.O f.9 oil 27 I3 2. 7 -------- ------ -------- 6.9 5.2 6.3 8.5 91 66 23 2.I -------- ------ -------- 6.-i 

3.9 5.-i 8.9 

f80 f20 320 230 170 ------ 1.8 I. 7 l.I 1.3 1.6 2.I 2.6 50 35 I5 3.3 1.3 ------ 7.0 6.5 f.3 f.S 6.1 8.2 9.6 56 f6 30 I5 6.1 ------ 5.8 5.2 f.2 "·" 5.1 6.1 7.-i 22 15 6.5 2.6 I.6 ------ 7.-i 7.3 5.5 6.1 7.3 8.6 9.3 

79 f9 I8 3.I 1.3 ------ 6.6 6.3 3.7 ••• 5.8 8.3 9.6 81 51 12 I.S -------- ------ -------- 6. 7 f.3 6.-i 9.1 

59 f2 2I 7.9 3.-i ------ 6.I 5.8 f. I f.6 5.6 7.0 8.2 lfO IOO flj 16 6.9 ------ 5.0 f.6 2.8 3.3 f.5 6.0 7.2 120 71 21 f.3 1.6 ------ 6.2 5.8 3.1 3.8 5.6 7.9 9.3 

11 6. 7 2.0 -------- -------- ------ -------- -------- 9.0 160 90 8.5 1.5 1.0 ------ 6.3 6.-i 2.6 3.5 6.9 9.-i 10.0 8I 61 23 5. 7 2.2 ------ 6.2 5. 7 3.6 f.O 5.4 7.5 8.8 I5 11 5.5 2.5 I. 7 ------ 7.6 7.6 6.I 6.5 7.5 8.6 9.2 28 If 3.-i I.l -------- ------ -------- 8.0 6.2 8.2 9.8 320 250 120 17 f.2 ------ f.8 3.9 1.6 2.0 3.1 5.9 7.9 27 12 3.9 I.f -------- ------ -------- 7.9 6.-i 8.0 9.5 35 21 8.1 2.4 -------- ------ -------- 7.1 5.6 6.9 8. 7 120 100 60 20 10 1.2 f.8 f.5 3.1 3.3 f.l 5.6 6.6 240 180 72 12 3.0 ' ------ 5.2 ••• 2.1 2.5 3.8 6.-i 8.-i 25 If f.6 I.3 -------- ------ -------- 7.9 6.2 7.8 9.6 180 130 58 7.6 2.5 ------ 5.6 5.0 2.5 2.9 f.l 7.0 8.6 270 240 180 110 76 f.O 2.8 2.6 1.9 2.1 2.5 3.2 3. 7 49 29 82 2.1 -------- ------ -------- 7.0 5.1 6.9 8.9 38 17 5.2 1." _____ , __ ------ - . - - - ~ -- i. 7 5.9 7.6 9.5 21 13 4.8 1.4 -------· ------ -------- 7.9 6.3 7. 7 9. 5 90 41 9.9 1.3 ---·---- ------ -· --- -- 7.1 4.6 6. 7 9.6 16 9. 6 3.5 1.4 -------· ------ -· ------ 8.1 6. 7 8.2 9. 5 81 57 28 11 4.8 -----·- 5. 7 5.3 3.6 4.1 5.2 6. 5 7. 7 62 48 26 10 4.9 -----· 5.8 5.5 4.0 4. 4 5.3 6.6 7. 7 

Deviations 

.. I QD, ~I 

2.6 1.6 0.-if 

-------- -------- --------

-------- 2.5 --------

-------- -------- -------- 1.0 .5 .57 

-------- -------- --------

-------- 1.3 -------- 2.1 .9 • 75 

-------- 1.8 -------- 1. 7 .9 .30 

2.0 l.f .39 

.8 .5 .30 

.7 .3 .f9 

I. I .6 .39 

-------- 1. 7 --------

-------- 2.5 -------- .7 •• .23 

2.6 I. 7 .M 

I.6 .8 .« 

I.9 I.3 .07 

3.0 2.0 .28 

-------- 2.-i -------- 2.1 I.2 .28 

2.2 1.3 .25 

3.1 2.0 .19 

-------- -------- -------- 3.7 3.0 -.16 

2.6 I. 7 .30 

1.6 I.l .08 

-------- I.8 -------- 3.1 1.9 .55 

-------- 1.5 --------

-------- 1.6 --------

I.8 1.2 .« 

3.2 2.0 .fli 

-------- 1. 7 --------

3.1 2.0 .f7 

.9 .6 .36 

-------- 1.9 --------

~ --- ---- 1.8 --------

-·------ 1.6 -----.-

-----· -- 2.5 --------

-------- l.f --------

2. 0 1.2 .25 

1.8 1.1 .31 

Skewness 

I Skq• 

QD• Skq• 

O.M 0.53 

---------- -------- .oil 1.01 

---------- -------- .c .20 

---------- -------- .24 .33 

.58 .53 

.13 .24 

.11 .IO 

.29 .fO 

.24 .12 

.c .13 

.u .~ 

.36 .60 

.39 .97 

.00 .Of 

.28 .-iS 

.23 .I9 

.Of .06 

.27 .M 

.I3 .32 

.I6 .20 

.I3 .I7 

.13 .27 

---------- -------- -.16 -.f6 

.I8 .30 

.06 .06 

-.11 -.2I 

.fli .88 

-.06 -.07 

.I2 .18 

.36 .u 

.32 .62 

.06 .11 

.43 .88 

.27 .15 

.M .07 

.05 .09 

.11 .17 

.18 .« 

-.05 -.07 

.13 .16 

. 21 . 24 

I Sk 

O.fS 

-------- .25 

--------

.76 

--------

.63 

.-iS 

• 72 

.~ 

.57 

.M 

.83 

.90 

.43 

.26 

.M 

.51 

. 77 

.92 

.f7 

.M 

.75 

• 79 

.69 

-------- I.87 

.66 

.9I 

I.33 

.30 

I.lO 

.77 

.56 

.u 

.86 

.29 

.81 

.91 

.88 

. 79 

.M 

1.10 

.80 

.71 

Finer 

than3 

microns 

(percent) 

15 

58 

23 

f6 

7 

43 

f8 

12 

27 

9 

9 

6 

6 

9 

26 

27 

7 

24 

12 

28 

24 

30 

5 I 

11 

22 

59 

37 

18 

31 

f7 

1-i 

43 

28 

7 

16 

fO 

17 

5 

20 

38 

as 

33 

46 

14 

12 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C57 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-KeUleman City area-Continued 

Sample 

57 CAL 151__ ___ 

7 CAL 152 _____ 

7 CAL 153__ ___ 

7 CAL 154__ ___ 

7 CAL 155 _____ 

7 CAL 156 _____ 

7 CAL 157 _____ 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

7 CAL 158 _____ 

7 CAL 159 _____ 

7 CAL 160 _____ 

7 CAL 16L ____ 

7 CAL 162 _____ 

7 CAL 163 _____ 

5 7 CAL 164 _____ 

5 7 CAL 165 _____ 

7 CAL 166 _____ 

5 7CAL167 _____ 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

7 C.AL 168 _____ 

7 CAL 169 __ -- 7 CAL 170 _____ 

7 CAL 17L ____ 

7 CAL 172 _____ 

7 CAL 173 _____ 

7 CAL 174 _____ 

7 CAL 175 _____ 

7 CAL 176 _____ 

7 CAL 177 _____ 

7 CAL 178 _____ 

7 CAL 179 _____ 

5 7 CAL 180 _____ 

5 

5 

5 

5 

5 

7 CAL 18L ____ 

7 CAL 182 _____ 

7 CAL 183 _____ 

7 CAL 184 _____ 

7 CAL 185_ --

7 CAL 186 ____ 

7 CAL 187 _____ 

5 7 CAL 188 _____ 

5 

5 

7 CAL189 _____ 

7 CAL 190 ----

7 CAL 191 ----

7 CAL 192_ --

5 

5 

7 CAL 193 _____ 

7 CAL 194 _____ 

7 CAL 195 _____ 

5 7 CAL 196 ____ 

Depth 

below 

land 

surface 

(feet) 1 

(C) 

1,180 470 

1.1 

1,199 440 

1.2 

1, 209 250 

2. 0 

1, 216 640 

0.64 

1,232 270 

1. 9 

1,248 4,900 

-2.3 

I, 263 270 

1.9 

1, 284 340 

I. 6 1,291 200 

2.3 

1,306 450 

1.2 

1,321 340 

1.6 

1,347 420 

1.3 

1,357 370 

1.4 

1,376 260 

1.9 

1,392 450 

1.2 

1,417 310 

1.7 

1,428 330 

1.6 

1,433 380 

1.4 

1,454 390 

1.4 

1,480 350 

1.5 

1,484 260 

1. 9 

1,498 370 

1.4 

1,518 320 

1.6 

1,528 410 

1.3 

1,539 270 

1.9 

1,544 340 

1.6 

1,551 410 

1.3 

1,575 380 

1.4 

1,590 330 

1. 6 1,605 370 

1.4 

1,615 340 

1.6 

1,642 370 

1.4 

1,650 380 

1.4 

1,669 350 

1.5 

I, 678 220 

2.2 

1.699 320 

1.6 

1, 719 350 

1.5 

I, 728 300 

1.7 

I, 748 300 

1.7 

I, 780 290 

1.8 

1.800 410 

1.3 

I, 805 400 

1.3 

I, 831 230 

2-1 

I, 842 280 

1.8 

1,868 410 

1.3 

I, 873 290 

1.8 

Percentiles 

I 

5 

I 

16 

I 

25 

220 17 5.3 

340 200 140 

2.3 2.8 

140 50 33 

4.3 4.9 

310 170 120 

2.6 3.1 

170 130 100 

2.9 a. a 

1,100 600 510 

0. 7 1.0 

110 20 12 

200 92 40 

4.6 

71 22 14 

6.2 

290 160 110 

3.2 

150 58 30 

5.1 

280 170 120 

2.6 3.1 

130 28 16 

6.0 

120 39 26 

5.3 

150 32 15 

6.1 

210 100 49 

3.3 4.4 

180 70 38 

4. 7 270 140 87 

2.8 3. 5 

260 110 43 

3.2 4. 5 

190 68 36 

4.8 73 30 23 

5_1 5.4 

260 130 75 

2.9 3. 7 130 60 41 

4.1 4.6 

300 180 120 

2.5 3.1 

160 50 26 

5.3 

200 130 100 

2.9 3.3 

300 210 170 

2.3 2.6 

270 150 97 

3.4 

190 85 55 

3.6 4.2 

240 110 59 

3.2 4.1 

220 130 77 2.9 a. 7 240 140 97 

2.8 3.4 250 86 19 

200 61 33 4.0 4.9 

86 38 24 

5.4 

210 150 120 

2. 7 3.1 

120 35 22 

5. 5 

180 66 39 

4. 7 130 27 15 

5. 2 6.1 

88 40 28 

5. 2 

290 150 88 

270 150 100 2. 7 3.3 

54 18 13 

5.8 6.3 

170 61 34 

4.9 

360 270 200 

1.9 2.3 

150 85 71 

3.6 3.8 

(mic;ns) Means 

I I I I M,l QM, 

50 75 84 95 

(Md) 

Huron core-Continued 

1.6 -------- -- ·--· -- ------ -- ------ -------- 9.3 

37 5.4 1.9 ------ 5. 7 5.2 

4.8 7. 5 9.0 

15 6. 5 4.0 1.1 6.1 6.1 

6.1 7.3 8. 0 

36 7.4 3.5 ------ 5.4 5.1 

4.8 7.1 8.2 

54 14 3. 7 ------ 5.5 4. 7 4.2 6.2 8.1 

290 100 30 ------ 2.9 2.1 

1.8 3.3 5.1 

4.3 -------- ---- ---- ------ ---· ---- -------- 7.9 

5.4 1.4 -------- ------ -------- 7.1 

7.5 9.5 

5.1 1.4 -------- ------ -------- 7.8 

7.6 9.5 

14 1.6 -------- ------ -------- 6.2 

6.2 9.3 

9.0 1.8 -------- ------ -------- 7.1 

6.8 9.1 28 3. 7 2.0 ------ 5.8 5.6 

5.2 8.1 9.0 

4.1 1.0 -------- ------ -------- 8.0 

7.9 10.0 

10 2.8 -------- ------ -------- 6.9 6.6 8.5 

4.2 1.2 -------- ------ -------- 7.9 

7.9 9. 7 14 3.3 1.5 ------ 6.3 6.3 

6.2 8.2 9.4 

9.2 1. 7 -------- ------ -------- 7.0 

6.8 9.2 

23 5.1 1.8 ------ 6.0 5.6 

5.4 7.6 9.1 

10 2.8 1.0 ------ 6.6 6.5 6.6 8.5 10.0 

9.4 2.5 -------- ------ -------- 6. 7 6. 7 8.6 

12 5.1 2.6 ------ 6.8 6. 5 6.4 7.6 8.6 

14 2.6 1.0 ------ 6.5 6.2 

6.2 8.6 10.0 

14 3.6 1.3 ------ 6.8 6.4 

6.2 8.1 9.6 

39 7.1 1.9 ------ 5.8 5.1 

4. 7 7.1 9.0 

6.4 1.4 -------- ------ -------- 7.4 

7.3 9.5 

48 14 3.1 ------ 5.6 4. 7 4.4 6.2 8.3 

110 44 20 ------ 3.9 3.5 

3.2 4.5 5.6 

27 6.9 -------- ------ -------- 5.3 

5.2 7.2 

20 5.1 1.9 ------ 6.3 5.9 

5.6 7.6 9.0 

30 7.0 2.5 ------ 5.9 5.6 

5.1 7.2 8.6 

16 3.2 1.3 ------ 6.3 6.0 

6.0 8.3 9.6 

30 4.8 1.2 ------ 6.3 5.5 

5.1 7. 7 9. 7 ------ 3.6 -------- -------- ------ -------- -------- 8.1 

13 2.9 1.3 ------ 6.8 6. 7 6.3 8.4 9.6 

6.8 1.3 -------- ------ ---------- 7. 5 

7.2 9.6 

47 6.4 1.6 ------ 6. 0 5.2 

4.4 7.3 9.3 6. 4 1.4 ·------- ------ -------- 7. 5 

7.3 9. 5 

13 2. 5 -------- -----· ------- ~ 6. 7 6.3 8.6 I 5.2 1.8 1.0 ------ 7. 6' 7.6 

7.6 9.1 10.0 

9. 5 2.0 -------- ------ -------- 7.1 6. 7 9.0 

13 -------- -------- ------ -------- -------- 6.3 

37 8.9 5.0 2.3 5.2 5.1 

4.8 6.8 7. 6 7. 5 3.6 2.3 ------ 7.3 7. 2 

7.1 8.1 8.8 

8.9 1.5 -------- ------ -------- 7_1 

6.8 9. 4 

51 10 5. 7 2.3 4. 7 4. 5 

4.3 6. 6 7.5 

50 12 3. 4 ------ 5.9 5.1 

4.3 6. 4 8. 2 

Deviations Skewness Finer 

than3 

microns 

.. I QD, ~I I I 

(perSkq• cent) 

QD• Skq• Sk 

-------- ------- - ------ ---------- -------- -------- 66 

3.4 2.3 0.27 0.18 0.42 0.55 20 

1.8 1.2 .04 .03 .03 .95 13 

2.8 2.0 .20 .13 . 27 .69 14 

2.6 1.4 . 51 .37 .53 .48 14 

2.2 1.2 . 51 .30 .35 .61 9 

-------- -------- -------- -------- -------- 42 

-------- 2.4 -------- -.19 -.47 1. 92 38 

-------- 1.7 -------- .12 .20 . 75 38 

-------- 3.1 -------- .02 .07 .90 33 

-------- 2.0 -------- .14 .29 .67 31 

3.2 2.5 .19 .16 .41 . 57 22 

-------- 2.0 -------- .02 .04 .95 44 

-------- 1.6 -------- .14 .23 .73 26 

-------- 1.8 -------- -.01 -.02 1.02 43 

3.0 1.9 .06 .07 .13 .82 24 

-------- 2.2 -------- .09 .20 • 76 32 

3.1 2.0 .17 .06 .13 .84 19 

3.4 2.0 -.02 -.07 -.13 1.20 26 

-------- 1.9 -------- -.01 -.01 1.02 27 

1.8 1.1 .25 .14 .15 .81 17 

3.5 2.4 .08 .00 .00 .99 27 

2.8 1.8 .24 .11 .20 • 75 23 

3.3 2.0 .33 .21 .42 .56 18 

-------- 2.1 -------- .04 .08 .89 36 

2. 7 1.4 .46 .25 .36 .61 16 

1. 7 1.0 .45 .36 .35 .62 10 

-------- 1.9 -------- .03 .06 .92 20 

2. 7 1.7 .24 .15 .26 • 70 19 

2. 7 1.5 .31 .36 .56 .46 17 

3.3 2.3 .09 .01 .02 .96 24 

3.4 2.2 .35 .22 .47 .52 21 

-------- -------- -------- ---------- -------- -------- 39 

2.8 1.8 .19 .23 .40 .67 25 

------- 2.1 ---" --- .13 .28 .67 36 

3.3 2.1 . 49 .36 . 76 .35 19 

-------- 2. 0 -------- .10 .20 . 75 35 

-------- 2. 0 ------·- .20 .39 .58 27 

2. 4 1.5 .00 .00 .00 1.00 37 

-------- 1.9 -------- .18 .34 .62 30 

-------- --------- ------ ------------ ----- -------- 37 

2. 4 1.7 .18 .17 .30 .65 8 

1.5 .9 .15 .14 .13 .83 21 

-------- 2.2 -------- .14 .32 .64 34 

2.8 2. 2 .H .09 .19 . 77 7 

2.3 1.3 .67 . 61 . 78 .34 15 
C58 MECHANICS OF AQUIFER SYSTEMS 

TABLE 5.-Particle-size data for sediments from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area-Continued 

Depth Percentiles ( mi~ons) Means Deviations Skewness Finer 

below thana 

Sample land micron 

surface 

I I I I I I I >41 I QD, ~I I I 

(per- (feet) 1 5 16 25 50 75 84 95 QM• ,. Skq• Skq• Sk cent) (C) (Md) QiJ-; 

Huron core-Continued 

57 CAL 197 _____ 1,900 230 65 22 14 5.0 1. 2 -------- ------ -------- 7.9 1. 8 0.16 0.29 0.67 39 

2.1 6. 2 7.6 9. 7 57 CAL 198 _____ 1,913 300 160 61 32 7.2 1.3 -------- ------ -------- 7.3 2.3 . 07 .16 0. 80 37 

1. 74 5. 0 7.1 9.6 

57 CAL 199 _____ 1,937 420 310 200 120 9.1 1. 2 -------- ------ -------- 6.4 3.3 -.12 -.40 1. 74 35 

1.3 3.1 6. 8 9. 7 57 CAL 200 _____ 1,957 420 280 190 150 49 1.2 -------- ------ -------- 6.2 3. 5 .54 1.87 0.07 29 

1.3 2. 7 4.4 9. 7 57 CAL 20L ___ 1,976 390 290 190 130 7.3 -------- -------- ------ -------- -------- -------- -------- -------- ---------- -------- -------- 41 1.4 7.1 

57 CAL 202__ ___ 1,993 340 170 19 5.5 1.9 -------- -------- ------ -------- -------- -------- -------- -------- ---------- -------- -------- 62 

1.6 9.0 

57 CAL 203__ ___ 2,020 370 220 65 23 6.6 2. 0 -------- ------ -------- 7. 2 1.8 -.02 -.04 1.06 31 

1.4 5.4 7.2 9. 0 

57 CAL 204 _____ 2, 050 320 150 61 37 13 4. 7 3.3 1. 6 6.1 6. 2 2.1 1.5 -0.06 -.02 -.03 1. 03 14 1. 6 4.0 4.8 6.3 7. 7 8. 2 57 CAL 205 _____ 2, 064 330 140 29 10 2.0 -------- -------- ------ -------- -------- -------- -------- -------- ---------- -------- -------- 56 

1.6 9.0 

57 CAL 206 _____ 2, 092 410 220 37 7. 7 2.9 1.4 -------- ------ -------- 8. 2 -------- 1.2 -------- -.15 -.18 1.28 51 

1.3 7. 0 8.4 9,5 

TABLE 6.-Particle-size data for selected fine-grained sediments 

from cores and streams, Los Banos-Kettleman City area TABLE 6.-Particle-size data for selected fine-grained sediments 

from cores and streams, Los Banos-.KeUleman City area-Con . 

[Particle-size analyses made by the Hydrologic Laboratory of the U.S. Geological Survey, Denver, Colo.] 

Depth Percentiles (microns) Sand Silt Clay below (>62p) (4p-62p) (<4~t) 

Sample land 

1•1 I I 1'•1 M 

(per- (per- (per- surface 1 16 25 50 cent) cent) cent) (feet) 

Oro Lorna oore 

59 CAL 279_ 154 220 120 51 27 3.8 ---- ---- 13.2 36.5 50.3 

59 CAL 280_ 472 60 30 14 10 5. 7 2.4 1. 3 .8 61.2 38.0 

59 CAL 28L 724 110 48 36 19 3.0 ---- ---- 1. 6 45.6 52.8 

59 CAL 282_ 823 120 47 25 14 3.0 ---- ---- 2.2 43.4 54.4 

Mendota oore 

59 CAL 283_ 75 100 74 53 45 14 ---- ---- 9.2 51.5 39.3 

59 CAL 285_ 746 60 43 32 25 11 2.8 1.6 .8 68.2 31.0 

59 CAL 286_ 981 55 34 16 6.6 1.1 ---- ---- .4 31.6 68.0 

59 CAL 287_ 1,443 60 32 16 9.8 2. 7 ---- ---- .4 43.3 56.3 

Cantua Creek core 

59 CAL 288_ 418 80 50 31 17 1.9 ---- ---- 2.0 41.0 57.0 

59 CAL 289_ 572 58 43 20 8. 2 1.3 ---- ---- .4 33.2 66.4 

59 CAL 290_ 902 120 80 47 21 1.5 ---- ---- 10.0 26.0 64.0 

59 CAL 29L 1,238 40 20 7_1 3. 7 1.0 ---- ---- .0 24.0 76.0 

59 CAL 292_ 1,632 43 23 11 7.1 3.3 1. 5 ---- .0 43.0 57.0 

59 CAL 293_ 1,952 60 40 15 5.9 1. 3 ---- ---- .8 28.8 70.4 

~=ro~ Sample land 

surface 

(feet) 

Sand Silt Clay 1--:----;--;--;------;----,---1 (>62p) (4p-62p) (<4p) 

I I I I I I 

(per- (per- (per5 16 25 50 75 84 cent) cent) cent) 

Percentiles (microns) 

Huron core 

59 CAL 294_ 313 27 12 6.3 4.6 2. 2 ---- ---- 0.0 29.6 70.4 

59 CAL 295_ 735 59 48 42 36 18 1.3 ---- .4 67.7 31.9 

59 CAL 296- 905 100 60 22 11 2.6 ---- ---- 4.8 37.4 57.8 

59 CAL 297- 1,387 55 43 25 15 2.9 ---- ---- .0 46.3 53.7 

59 CAL 298- 1, 801 110 72 50 43 12 1.5 ---- 8. 5 53.5 38.0 

59 CAL 299_ 2,093 100 55 27 15 4.2 1.9 ---- 3.2 48.3 48.5 

Bed sediment, Little Panoche Creek 

59 CAL 278-1 o 124o 1160 I 120 l11o I 63,19,6. 71 50.41 37.81 11.8 

Bank sediment, Panoc:he Creek 

59 CAL 277-1 o 1180 1120 1 90 1 721 31 ,4. 1 II. 21 30-21 44. sj 25.0 

TABLE 7.-Particle-size data for selected well-sorted sands from Mendota, Cantua Creek, and Huron cores, Los Banos-Kettleman City area 

[Sieve analyses made by R- H. Meade] 

------~--------- --------------

Depth below 

land surface I _ (microns) Percentiles ~</>~ 

(feet) 

I I 

I I I I 

I 1 50 

I 

(C) 

I 

5 16 25 (Md) 75 84 

I 

Mendota oore 

232 _____________ 370 240 180 160 140 110 88 

1. 4 2. 5 2. 6 2. 8 3. 2 3. 5 472 _____________ 350 250 190 170 160 80 25 

1. 5 2. 4 2. 6 2. 6 3. 6 5. 3 833 _____________ 440 290 220 200 150 100 67 

1.2 2. 2 2. 3 2. 7 3. 3 3. 9 

Deviation 

95 "• I QD., 

I 

47 0. 5 0. 3 

------ 1.5 .5 

------ .9 .5 

Skewness 

I 

Skq• "• QD• 

0. 54 0. 26 

. 84 . 85 

. 43 . 16 

I 

I 

Skq., 

0. 0 7 

6 

8 

. 4 

.0 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C59 

TABLE 7.-Particle-size data for selected well-sorted sands from Mendota, Cantua Creek, and Huron cores, 

Los Banos-Kettleman City area-Continued 

. (microns) Deviation Skewness 

Depth below Percentlles -.-

land surface 

(feet) 

I I I I I I I I I 

1 50 Skq.; (C) 5 16 25 (Md) 75 84 95 tT.; QD.; a.; QD.; 

Mendota core-Continued 

880 __ - - - - - - - - - - - 430 330 260 230 170 120 80 ------ 0. 8 0. 5 0. 27 0. 06 

1.2 1.9 2.1 2.6 3. 1 3. 6 1, 077 _____________ 700 320 240 210 150 97 60 ------ 1.0 .6 . 32 . 12 

0. 51 2. 1 2. 3 2.7 3.4 4. 1 1, 127 _____________ 1, 200 750 410 310 210 160 120 73 .9 .5 -. 09 -.19 

-0.26 1. 3 1.7 2.3 2. 6 3. 1 1, 251_ ____________ 2, 100 1, 200 870 720 430 260 190 50 1.3 . 7 -. 09 -. 03 

-1.1 0. 2 0. 47 1.2 1.9 2. 4 1, 347 _____________ 590 390 300 280 210 150 110 ------ .7 .5 . 29 . 09 

0. 76 1.7 1. 8 2.3 2. 7 3. 2 

Cantua Creek core 

581 _____________ 1,700 1,000 500 410 300 220 180 100 0. 7 0. 4 -0.01 -0.02 

-0.77 1. 0 1. 3 1. 7 2. 2 2. 5 

590 __ ----------- 690 400 260 220 160 100 87 54 .8 .6 .11 . 19 

0. 54 1. 9 2.2 2. 6 3. 3 3. 5 633 _____________ 620 220 170 150 110 76 65 38 . 7 .5 . 10 . 10 

0. 69 2.6 2.7 3.2 3. 7 3. 9 774 _____________ 420 310 220 190 150 94 68 ------ .8 . 5 . 34 . 32 

1.3 2. 2 2.4 2.7 3. 4 3. 9 

824 __ ----------- 520 230 170 150 130 85 57 ------ .8 .4 . 51 . 47 

0.94 2.6 2.7 2.9 3. 6 4. 1 997 _____________ 1, 100 760 490 440 330 250 210 110 .6 .4 . 02 -. 02 

-0.13 1. 0 1. 2 1. 6 2. 0 2. 3 1,034 _____________ 1, 100 580 340 300 250 200 170 74 . 5 .3 . 03 . 10 

-0.13 1. 6 1. 7 2.0 2.3 2. 6 1,228 _____________ 1,400 830 480 370 190 110 98 60 l. 1 .9 -.18 -.11 

-0.49 1.1 1. 4 2.4 3. 2 3. 4 1,363 _____________ 500 310 230 210 170 140 120 55 .5 .3 . 06 -. 07 

1.0 2.1 2.3 2.6 2.8 3. 1 1,420 _____________ 2, 100 980 530 400 210 130 110 53 l. 1 . 8 -.18 -.15 

-1.07 0. 9 1. 3 2.3 2.9 3. 2 1,550 _____________ 1, 100 780 490 4-20 310 240 200 110 .6 .4 -. 03 -.10 

-0.13 1. 0 1. 3 1. 7 2. 1 2. 3 1,950 _____________ 890 510 340 290 270 230 190 97 .4 .2 . 21 . 37 

0. 17 1. 6 1. 8 1. 9 2. 1 2. 4 

Huron core 

632 _____________ 370 230 180 160 110 56 35 ------ 1.2 0. 8 0. 40 0. 29 

1.4 2.5 2.6 3.2 4.2 4.8 72L ____________ 260 160 120 110 85 62 47 ------ .7 .4 . 25 . 07 

1.9 3. 1 3. 2 3.6 4. 0 4. 4 960 _____________ 1, 300 860 460 280 140 110 92 55 1.2 .7 -. 48 -. 49 

-0.38 1. 1 1.8 2. 8 3. 2 3. 4 

I 

Skq.; 

0. 0 3 

7 

9 

2 

4 

.0 

-. 0 

-.0 

.0 

-0.01 

.11 

. 05 

. 16 

. 19 

-. 01 

. 03 

-.10 

-. 02 

-.12 

-. 04 

. 06 

0. 2 

.0 

-. 3 

2 

3 

3 
060 

Sample 

58 CAL 99 ______ 

58 CAL 100 _____ 

58 CAL lOL ___ 

58 CAL 102 _____ 

58 

58 

58 

58 

58 

58 

CAL 103 _____ 

CAL 104 _____ 

CAL 105 _____ 

CAL 106 _____ 

CAL 107 _____ 

CAL 108 _____ 

8 CAL 109 _____ 

58 

58 

58 

CAL 110 _____ 

CAL 11L ___ 

CAL 112 _____ 

8 CAL 113 _____ 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

58 

CAL 11L ___ 

CAL 115 _____ 

CAL 116__ ___ 

CAL 117__ ___ 

CAL 118 _____ 

CAL 119 _____ 

CAL 120 _____ 

CAL 12L ____ 

CAL 122 _____ 

CAL 123 _____ 

CAL 124 _____ 

CAL 125 _____ 

CAL 126 _____ 

CAL 127 _____ 

CAL 128 _____ 

CAL 129 _____ 

CAL 130 _____ 

CAL 13L ____ 

CAL 132 _____ 

CAL 133 _____ 

CAL 134_ ----

CAL 135 _____ 

CAL 136 _____ 

CAL 137 _____ 

CAL 138 _____ 

CAL 139 _____ 

CAL 140 _____ 

CAL 141_ ____ 

CAL 142 _____ 

CAL 143 _____ 

Depth 

below 

land 

surface 

(feet) 

31 

70 

119 

155 

194 

236 

269 

287 

295 

305 

317 

321 

336 

343 

353 

363 

371 

418 

427 

443 

451 

465 

476 

482 

496 

509 

511 

523 

534 

546 

561 

582 

595 

601 

616 

622 

631 

644 

654 

660 

673 

683 

694 

705 

724 

1 

(C) 

1, 700 

-0.8 

360 

1. 5 

1,800 

-0.9 

610 

0. 7 1,400 

-0.5 

1, 000 

0.0 

1,300 

-0.4 

125 

3. 0 

45 

4.5 

790 

0.3 

610 

0. 7 500 

1. 0 

1,600 

-0.7 

400 

1.3 

360 

1. 5 

1,400 

-0.4 

700 

0.5 

560 

0.8 

190 

2.4 

750 

0.4 

125 

3. 0 

300 

1.7 

380 

1. 4 300 

1.7 

610 

0. 7 910 

0.1 

420 

1.3 

420 

1.2 

300 

1.7 

350 

1.5 

230 

2.1 

1, 700 

-0.7 

390 

1.4 

350 

1.5 

1,000 

0.0 

410 

1.3 

610 

o. 7 

560 

o. 8 

800 

0.3 

420 

1.3 

930 

0.1 

220 

2. 2 710 

0. 5 

400 

1.3 

400 

1.3 

MECHANICS OF AQUIFER SYSTEMS 

TABLE 8.-Particle-size data for cored sediments, Tulare-Wasco area 

[Particle-size analyses made by Hydrologic Laboratory of the U.S. Geological Survey, Denver, Colo.] 

Percentiles ( mic;ons) 

Deviations 

Mode 

(mic;ons) M• 

I I I I I I I 

QD• I .. ,. 2 5 16 25 (Md) 75 84 95 

Pixley core 

1,500 950 440 280 43 6. 5 ------ ------ ------------ -------- -------- 2. 7 

-0.6 0.1 1. 2 1.9 4. 5 7.3 

280 170 80 54 20 6.1 2. 5 ------ 34 6.1 2.5 1. 6 

1.8 2.5 3.6 4.2 5.6 7.4 8.6 4.9 

1,600 1,200 530 280 49 8.2 3.1 ------ 36 4.6 3. 7 2.5 

-0.7 -0.3 0.9 1.8 4.3 6.9 8.3 4.8 

470 280 160 130 65 23 9.9 ------ 52 4.6 2. 0 1. 2 

1.1 1.8 2.6 3.0 4.0 5.4 6. 7 4.3 

1,000 630 300 210 74 20 4.6 ------ 42 4. 7 3.0 1. 7 

0. 0 0. 7 1.7 2.3 3.8 5. 7 7.8 4.6 

700 400 170 110 37 5.1 1.6 ------ 38 5. 9 3.4 2. 2 

o. 5 1. 3 2.6 3.2 4.8 7.6 9.3 4. 7 

920 630 300 180 30 3. 7 2. 0 ------ 35 5.4 3.6 2.8 

0.1 0. 7 1. 7 2.5 5.1 8.1 9.0 4.8 

68 48 30 24 13 3. 6 1.2 ------ 28 7. 4 2. 3 1.4 

3.9 4.4 5.0 5.4 6.2 8.1 9. 7 5.2 

39 31 21 18 8.4 1.7 ------ ------ ------------ -------- -------- 1. 7 

4. 7 5. 0 5.6 5.8 6.9 9.2 

650 490 360 310 220 150 130 36 230 2.2 .8 .5 

0.6 1. 0 1. 5 1. 7 2.2 2. 7 3.0 4.8 2.1 

400 210 83 57 27 7. 5 1.3 ------ 36 6.6 3. 0 1. 5 

1.3 2.3 3.6 4.1 5.2 7.1 9.6 4.8 

430 350 240 160 40 5. 0 1.2 ------ 38 5.9 3.8 2. 5 

1. 2 1. 5 2.1 2. 7 4.6 7.6 9. 7 4. 7 

1,300 830 340 150 16 1.6 ------ ------ ------------ -------- -------- 3.3 

-0.4 0.3 1.5 2.8 6.0 9.3 

290 140 37 22 6.9 1.9 1. 0 ------ ------------ 7.4 2.6 1.7 

1.8 2.8 4.8 5.5 7. 2 9. 0 10.0 

270 180 88 59 21 2.3 ------ ------ 35 -------- -------- 2.3 

1. 9 2. 5 3.5 4.1 5. 6 8.7 4.8 

950 600 260 160 53 10 3.1 ------ 42 5.1 3.2 2. 0 

0.1 0. 7 1.9 2.6 4.2 6. 6 8.3 4.6 

580 310 71 47 21 5. 5 1.1 ------ 32 6.9 3.0 1.5 

0.8 1.7 3.8 4.4 5.6 7.5 9.9 4. 9 

390 230 74 42 13 1. 7 ------ ------ ------------ -------- -------- 2.3 

1. 4 2.1 3.8 4.6 6.3 9.2 

160 110 48 31 11 ------ ------ ------ 31 -------- -------- -------- 2. 7 3.2 4.4 5.0 6. 5 5.0 

560 250 34 18 5.1 ------ ------ ------ ------------ -------- -------- -------- 0.8 2.0 4.9 5.8 7.6 79 49 27 20 9.9 2.8 1.1 ------ 24 7. 5 2.3 1.4 

3. 7 4.4 5.2 5.6 6. 7 8.5 9.8 5.4 

200 110 51 38 20 6. 0 1. 7 ------ 32 6. 7 2.5 1. 3 

2.3 3.1 4.3 4. 7 5.6 7.4 9.2 5. 0 

280 190 120 83 32 7.1 2.8 ------ 42 5.8 2. 7 1.8 

1.8 2.4 3.1 3.6 4.9 7.1 8.5 4.6 

200 110 25 12 3.5 ------ ------ ------ ------------ --- ---- ------- -------- 2.3 3.2 5.3 6.3 8.2 

440 320 150 88 25 3. 0 ------ ------ 36 -------- -------- 2.4 

1.2 1.7 2. 7 3. 5 5.3 8. 4 4.8 

660 370 140 88 32 7.8 2.2 ------ 37 5.8 3.0 1.7 

0.6 1.4 2.8 3. 5 5.'0 7. 0 8.8 4.8 

350 210 70 3S 9.1 1.1 ------ ------ ------------ -------- -------- 2.5 

1.5 2.3 3.8 4. 7 6.8 9.8 

360 240 150 120 27 2.3 ------ ------ ------------ -------- -------- 2.8 

1.5 2.1 2. 7 3.1 5.2 8.8 

230 180 120 94 54 22 10 1.1 52 4.8 1.8 1.0 

2.1 2. 5 3.1 3. 4 4.2 5.5 6.6 9.8 4.3 

250 90 27 16 5. 4 1.4 ------ ------ ---------·-- -------- ------- 1.7 

2. 0 3. 5 5.2 6. 0 7. 5 9. 5 

160 110 64 47 24 7.5 3.4 -----· 26 6.1 2.1 1. 3 

2.6 3.2 4. 0 4. 4 5.4 7. 0 8.2 5.2 

1, 400 930 640 540 300 140 81 ------ 420 2.1 1.5 1.0 

-0.5 0.1 0.6 0. 9 1.8 2.9 3.6 1.2 

300 190 88 45 8.8 2.2 1.1 ------ ------------ 6. 7 3.2 2.2 

1.7 2.4 3. 5 4. 5 6.8 8.9 9.9 

250 160 81 55 22 6.4 2.5 ------ 34 6.1 2.5 1.6 

2.0 2.6 3.6 4. 2 5. 5 7.3 8. 7 4.9 

810 590 170 62 11 1.8 ------ ------ ------------ -------- -------- 2.6 

0.3 0.8 2. 5 4.0 6. 5 9.1 

350 270 150 110 52 20 11 ------ 44 4.6 1. 9 1.2 

1.5 1.9 2.8 3. 2 4.3 5.6 6. 5 4. 5 

440 300' 180 140 77 28 9.0 ------ 78 4.6 2. 2 1. 2 

1.2 1.7 2.5 2.8 3. 7 5.1 6.8 3. 7 

420 300 180 140 68 19 6.0 ------ 80 4.9 2.4 1.4 

1. 3 1. 8 2.5 2.8 3.9 5.7 7.4 3.6 

570 360 140 77 26 5. 2 1.2 ------ 34 6.3 3. 5 1. 9 

0.8 1.5 2.8 3. 7 5.3 7.6 9.8 4.9 

360 290 190 140 72 27 11 ------ 51 4.4 2.0 1. 2 

1. 5 1.8 2.4 2.8 3.8 5. 2 6. 5 4.3 

720 490 180 100 29 5.8 1.4 ------ 35 6.0 3. 5 2.1 

0. 5 1.0 2. 5 3.3 5.1 7.4 9. 5 4. 9 

150 100 59 44 24 10 5. 2 ------ 33 5.8 1.8 1.1 

2. 7 3. 3 4.1 4. 5 5.4 6.6 7.6 4.9 

500 380 250 180 78 18 3. 7 ------ 160 5.0 3.0 1.7 

1.0 1.4 2.0 2.4 3. 7 5.8 8.1 2.6 

310 210 125 92 45 20 10 1.7 40 4.8 1.8 1.1 

1. 7 2.3 3.0 3.4 4. 5 5.6 6.6 9.2 4.6 

310 190 69 43 16 4.6 1.9 ------ 31 6. 5 2.6 1.6 

1 .7 2 4 3. 8 4. 5 6. 0 7. 8 9.1 5.0 

Skewness 

Skq• a• QD• 

-------- 0.01 

0. 21 .11 

.08 .02 

.34 .20 

.33 .12 

. 35 .28 

.08 .08 

.49 . 37 

-------- .37 

.09 .08 

.46 .26 

.32 • 21 

-------- .02 

.09 .05 

-------- .37 

. 28 .19 

.42 .25 

-------- .24 

-------- ----------

-------- ----------

.37 .28 

.46 .32 

.32 .23 

-------- ---. ------

-------- . 25 

.28 .16 

-------- .18 

-------- . 25 

.35 .23 

-------- .10 

. 33 . 27 

. 25 .13 

-.04 -.07 

• 25 .14 

-------- .03 

.20 .13 

.43 .24 

.43 .28 

.29 .19 

.32 .17 

.24 .11 

. 27 .18 

.44 .26 

.19 .06 

.19 .12 

Skq• 

0. 01 

.17 

.04 

.25 

.20 

.62 

.23 

. 51 

.63 

.04 

.38 

.51 

.05 

.08 

.85 

.39 

.39 

. 57 

--------

--------

.41 

.43 

. 41 

--------

. 60 

.28 

.46 

. 71 

. 24 

.17 

. 36 

.1~ 

-.16 

.22 

.07 

.15 

.28 

.40 

.37 

.20 

.23 

.19 

.43 

.06 

.20 

Finer 

than3 

micron 

(percent) 

2 

1 

1 

1 

1 

8 

6 

3 

2 

22 

23 

3 2 

1 

3 

9 

22 

0 

3 

1 

2 

26 

6 

0 

3 

3 2 

0 

26 

0 

6 

46 

4 

2 

1 

2 4 

1 

3 

2 

3 

1 

3 

1 

5 

8 

5 

4 

3 

9 

1 

1 

1 

2 

20 

0 

20 

1 

1 5 

2 0 
Sample 

58 CAL 144 _____ 

58 CAL 145 _____ 

59 CAL 310 _____ 

59 CAL 311 _____ 

59 CAL 312 _____ 

59 CAL 313 _____ 

59 CAL 314 _____ 

59 CAL 315__ ___ 

59 CAL 316 _____ 

59 CAL 317__ ___ 

59 CAL 318 _____ 

59 CAL 319 _____ 

59 CAL 320 _____ 

59 CAL 321__ ___ 

59 CAL 322 _____ 

59 CLA 323 _____ 

59 CAL 324 _____ 

59 CAL 325 _____ 

59 CAL 326 _____ 

59 CAL 327 _____ 

59 CAL 328 _____ 

59 CAL 329 _____ 

59 CAL 330 _____ 

59 CAL 33L ___ 

59 CAL 332 _____ 

59 CAL 333__ ___ 

59 CAL 334 _____ 

59 CAL 335 _____ 

59 CAL 336 _____ 

59 CAL 337 _____ 

59 CAL 338 _____ 

59 CAL 339 _____ 

59 CAL 340 _____ 

59 CAL 34L ___ 

59 CAL 342 _____ 

59 CAL 343 _____ 

59 CAL 344 _____ 

59 CAL 345 _____ 

59 CAL 346 _____ 

59 CAL 347 _____ 

59 CAL 348 _____ 

9 CAL 349 _____ 

9 CAL 350 _____ 

PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C61 

Depth 

below 

land 

surface 

(feet) 1 

(C) 

731 320 

1.6 

748 830 

0.3 

55 3,400 

-1.8 

64 6,400 

-2.7 

85 3, 700 

-1.9 

93 2, 500 

-1.3 

103 4,900 

-2.3 

118 4,300 

-2.1 124 4,000 

-2.0 

133 2,300 

-1.2 

143 3, 000 

-1.6 

148 2,100 

-1.1 

157 1,300 

-0.4 

173 2,300 

-1.2 

177 2, 900 

-1.6 

187 6, 900 

-2.8 

204 3,100 

-1.6 

210 1, 900 

-0.9 221 3, 700 

-1.9 

232 9, 000 

-3.2 

240 4, 900 

-2.3 

252 9, 000 

-3.2 

260 3, 700 

-1.9 

274 4, 700 

-2.2 

285 1,100 

-0.2 

290 690 

0. 5 

301 2, 700 

-1.4 

316 2,200 

-1.1 

318 2,000 

-1.0 

329 2,500 

-1.3 

338 1,400 

-0.5 

357 2,300 

-1.2 

359 2,800 

-1.5 

370 2, 700 

-1.4 

375 2, 500 

-1.3 

389 810 

0.3 

399 2,600 

-1.4 

403 1, 500 

-0.6 

415 2,500 

-1.3 

423 3,000 

-1.6 

433 2,300 

-1.2 

443 1, 700 

-0.8 

459 2, 700 

-1.4 

TABLE 8.-Particle-size data for cored sediments, Tulare-Wasco area-Continued 

Percentiles ( mic;ons) Mode 

(mic;ons) 

I I I I I " I I I 2 5 16 25 (Md) 75 84 95 

Pixley core-Continued 

210 94 34 23 11 3. 9 1.9 ------ 23 

2.2 3.4 4. 9 5.4 6.6 8.0 9.0 5.4 

690 440 220 130 27 1.7 ------ ------ ------------ 0. 5 1.2 2.2 2. 9 5.2 9.2 

Richgrove core 

2,800 2,100 1,100 760 250 28 5.5 ------ 670 

-1.5 -1.1 -0.2 0.4 2.0 5.2 7.5 0.6 

4, 900 3,500 2,000 1,200 350 51 14 ------ 680 

-2.3 -1.8 -1.0 -0.3 1.5 4.3 6.1 0. 5 

3,000 2,100 820 460 110 22 5. 9 ------ 43 

-1.6 -1.1 0.3 1.1 3.2 5. 5 7.4 4. 5 

1,900 1,300 560 330 69 14 3. 5 ------ 36 

-0.9 -0.3 0.8 1.6 3. 9 6.2 8.2 4.8 

3,500 2,500 1,200 690 170 20 4.6 ------ ------------ -1.8 -1.3 -0.2 0. 5 2.6 5.6 7.8 

3,300 2,300 970 590 130 10 2.2 ------ ------------ -1.7 -1.2 0.0 0.8 2. 9 6.6 8. 9 

2,400 1,200 320 180 51 7. 5 1.6 ------ 40 

-1.3 -0.2 1.6 2. 5 4.3 7.1 9.3 4. 7 1,900 1,100 310 160 50 12 3. 2 ------ 40 

-Q.9 -0.2 1.7 2. 7 4.3 6.4 8.3 4.6 

2, 400 1,600 620 360 50 3.4 1.0 ------ ------------ -1.3 -0.7 o. 7 1.5 4.3 8.2 9.9 

1, 500 870 290 110 2.8 ------ ------ ------ ------------ -0.6 0.2 1.8 3. 2 8. 5 

1, 000 620 250 150 31 1.8 ------ ------ ------------ 0.0 0. 7 2. 0 2.8 5. 0 9.2 

1, 800 1,100 160 74 25 5.4 1.9 ------ 33 

-0.8 -0.1 2.6 3.8 5.3 7. 5 9. 0 4.9 

2, 400 1, 600 650 380 120 19 4.9 ------ 180 

-1.3 -0.7 0.6 1.4 3.1 5. 7 7. 7 2. 5 

5, 900 3, 900 2, 600 2,100 1,100 420 220 3. 2 1, 900 

-2.6 -2.0 -1.4 -1.1 -0.1 1.3 2. 2 8.3 -0.9 

2, 600 2, 000 970 580 74 2.9 ------ ------ ------------ -1.4 -1.0 o. 0 0.8 3.8 8.4 

1,300 700 220 130 35 9. 0 3.6 ------ 34 

-0.4 0. 51 2.2 2.9 4.8 6.8 8.1 4.9 

3, 000 2,100 810 400 52 8.3 2. 4 ------ 36 

-1.6 -1.1 0.30 1.3 4.3 6. 9 8. 7 4.8 

3, 400 1, 500 410 190 38 6.1 1.9 ------ 36 

-1.8 -0.5 1.3 2.4 4. 7 7. 4 9. 0 4.8 

3, 500 2, 500 890 490 100 12 3.4 ------ 38 

-1.8 -1.3 0. 2 1.0 3.3 6.3 8.2 4. 7 6,800 4, 900 3, 000 2, 400 1,300 550 300 ------ 2, 000 

-2.8 -2.3 -1.6 -1.3 -0.4 0.9 1.7 -1.0 

2,100 580 210 150 72 24 12 ------ 60 

-1.1 0.8 2.3 2. 7 3.8 5.4 6.4 4.1 

3,500 2,500 1,200 800 290 30 4.8 ------ 560 

-1.8 -1.3 -0.3 0.3 1. 8 5.1 7. 7 0.8 

820 480 240 180 85 23 8.6 ------ 130 

0.3 1.1 2.1 2.5 3.6 5.4 6. 9 2. 9 

500 250 110 64 26 7.6 3.4 ------ 34 

1.0 2.0 3.2 4.0 5.3 7.0 8.2 4. 9 

1, 700 960 470 340 170 23 2.8 ------ 210 

-0.8 0.1 1.1 1.5 2. 5 5.4 8.5 2.2 

1,600 910 310 200 82 19 6.1 ------ 110 

-0.7 0.1 1.7 2.3 3.6 5. 7 7.4 3.2 

1,400 740 290 200 98 27 12 ------ 160 

-0.5 0.4 1.8 2.3 3.3 5.2 6.4 2. 7 2,100 1,300 520 310 95 18 7.1 ------ 42 

-1.1 -0.4 0. 9 1.7 3.4 5.8 7.1 4.6 

1,000 450 200 150 56 9.9 3.6 ------ 46 

0.0 1. 2 2.3 2.8 4.2 6. 7 8.1 4.4 

1,900 920 270 160 55 16 6.2 ------ 40 

-0.9 0.1 1.9 ~· 7 4.2 6.0 7.3 4.6 

2,300 1,500 640 430 170 30 7. 5 1.2 290 

-1.2 -0.6 0.6 1.2 2.6 5.0 7.1 9. 7 1.8 

2,200 1,300 560 320 64 5.1 2.0 ------ 200 

-1.2 -0.4 0.8 1.7 4.0 7.6 9.0 2.3 

2,200 1,400 630 390 110 19 3.9 ------ 40 

-1.1 -0.5 o. 7 1.4 3.2 5. 7 8.0 4.6 

520 280 140 92 40 17 8.4 ------ 37 

1. 0 1.9 2. 9 3.4 4. 7 5. 9 6. 9 4.8 

2,300 1,600 550 290 55 7.4 2. 7 ------ 34 

-1.2 -0.6 0. 9 1.8 4.2 7.1 8. 5 4. 9 

1,200 720 310 210 63 5.1 1.8 ------ ------------ -0.2 0. 5 1.7 2.3 4.0 7.6 9.1 

2,100 1,500 840 600 230 52 17 ------ 550 

-1.1 -0.6 0.2 0. 7 2.1 4.3 5. 9 0.8 

2,500 1, 900 900 590 210 39 11 1.0 380 

-1.3 -0.9 0.1 0.8 2.3 4. 7 6. 5 9. 9 1.4 

1,600 910 300 180 63 17 7.0 ------ 42 -0.7 0.1 1.8 2. 5 4.0 5. 8 7.2 4.6 

1,200 700 260 160 30 5.4 2. 7 ------ 35 

-0.2 0. 5 1.9 2. 7 5.0 7. 5 8.5 4.9 

2,300 1, 700 670 390 100 21 8.3 ------ 43 

-1.2 -0.7 0.6 1.3 3.3 5.6 6.9 4. 5 

Mq, 

7.0 

--------

3. 7 

2.6 

3. 9 

4. 5 

3. 8 

4.4 

5. 5 

5.0 

5.3 

--------

--------

5.8 

4. 2 

. 4 

--------

5.1 

4. 5 

5. 2 

4.2 

.1 

4.4 

3. 7 

4.5 

5. 7 

4.8 

4.5 

4.1 

4.0 

5.2 

4.6 

3. 9 

4. 9 

4.3 

4. 9 

4. 7 

5.4 

3.0 

3.3 

4. 5 

5.2 

3. 7 

Deviations 

tT.p 

2.1 

--------

3.8 

3.6 

3.6 

3. 7 

4.0 

4.4 

3.8 

3.3 

4. 6 

--------

--------

3.2 

3. 5 

1.8 

--------

3. 0 

4.2 

3.9 

4. 0 

1.7 

2.1 

4.0 

2.4 

2. 5 

3. 7 

2.8 

2.3 

3.1 

2. 9 

2. 7 

3.2 

4.1 

3. 7 

2.0 

3.8 

3. 7 

2.8 

3.2 

2. 7 

3.3 

3.2 

QDq, 

1.3 

3.2 

2.4 

2.3 

2.2 

2.3 

2. 5 

2. 9 

2.3 

1.9 

3.4 

--------

3.2 

1.9 

2.1 

1.2 

3.8 

1.9 

2.8 

2. 5 

2. 7 

1.1 

1.3 

2.4 

1.5 

1.5 

1.9 

1.7 

1.5 

2.0 

1. 9 

1.7 

1.9 

3.0 

2.2 

1.2 

2.6 

2. 7 

1.8 

2.0 

1.7 

2.4 

2.1 

aq, 

.19 

0.44 

.30 

.18 

.18 

.30 

.35 

. 31 

.20 

. 22 

--------

--------

.16 

.30 

.28 

--------

.10 

.05 

.12 

.22 

. 26 

.27 

.48 

.38 

.18 

. 61 

.32 

.33 

.20 

.36 

.16 

.39 

.23 

.30 

.12 

.14 

.38 

.32 

.32 

.18 

. 06 

.15 

Skewness 

Skqq, 

QD.p 

.13 

.27 

0.33 

.22 

.05 

.02 

. 21 

.27 

. 21 

.11 

.16 

----------

. 29 

.18 

. 21 

.16 

• 22 

.01 

-.06 

. 07 

.16 

.16 

.20 

.39 

.28 

.14 

.49 

.24 

.27 

.16 

.28 

.09 

.29 

.23 

.14 

. 01 

.09 

.35 

.20 

.22 

.11 

.02 

.09 

Skqq, 

.17 

.84 

0. 79 

. 51 

.10 

.04 

.53 

. 78 

.47 

.21 

.53 

.------- .94 

.34 

. 45 

.19 

.85 

.03 

-.16 

.17 

.42 

.17 

.27 

.93 

.42 

.22 

.96 

.40 

.40 

.32 

. 55 

.15 

.55 

.69 

.31 

.01 

.25 

. 95 

.36 

.44 

.18 

.05 

.19 

Finer 

than 3 

micron 

(percent) 

20 

28 

1 5 

11 

1 

1 

1 

1 

1 

1 

2 

5 

5 

8 

9 

6 

2 4 

51 

3 0 

19 

13 

2 

1 

1 

2 

1 

1 

5 

5 

5 

7 

0 

5 

9 

4 

11 

1 

1 

1 

5 

6 

3 

8 

12 

1 5 

13 

9 

2 0 

1 

9 

17 

20 

10 

10 

12 

17 

10 
C62 

Sample 

59 CAL 35L ___ 

59 CAL 352__ ___ 

59 CAL 353 _____ 

59 CAL 354 _____ 

59 CAL 355 _____ 

59 CAL 356_ ----

59 CAL 357 _____ 

59 CAL 358_ ----

59 CAL 359_ ----

59 CAL 360 _____ 

59 CAL 36L ____ 

59 CAL 362 _____ 

59 CAL 363 _____ 

59 CAL 364 _____ 

59 CAL 365 _____ 

CAL 366_ ----

CAL 367 _____ 

9 CAL 368 _____ 

59 

59 

5 

5 

5 

5 

9 CAL 369 _____ 

9 CAL370 _____ 

9 CAL 371 _____ 

9 CAL 372_ --- _ 

9 CAL373 _____ 

9 CAL 374 _____ 

59 CAL 375 _____ 

59 CAL 376 _____ 

59 CAL 377 _ ----

59 CAL 378~----

9 CAL 379 _____ 

59 CAL 380 _____ 

9 CAL 38L ___ 

9 CAL 382 _____ 

5 

5 

9 CAL 383 _____ 

5 9 CAL 384 _____ 

59 CAL 385 _____ 

59 CAL 386 _____ 

59 CAL 387 _____ 

59 CAL 388 _____ 

59 CAL 389 _____ 

59 CAL 390 _____ 

59 CAL 391__ ___ 

59 CAL 392 _____ 

59 CAL 393 ____ 

59 CAL 394 ___ 

59 CAL 395 ___ 

59 CAL 396 _____ 

Depth 

below 

land 

surface 

(feet) 

468 

475 

488 

494 

507 

517 

531 

533 

544 

553 

565 

575 

583 

595 

608 

614 

623 

631 

648 

659 

669 

679 

687 

698 

709 

720 

726 

736 

744 

757 

763 

776 

778 

792 

844 

852 

861 

867 

917 

1, 037 

1,058 

1,099 

1,117 

1,156 

1, 184 

1, 241 

1 

(C) 

2,800 

-1.5 

2, 900 

-1.5 

1,600 

-0.6 

1,600 

-0.7 

1, 700 

-0.8 

2,000 

-1.0 

1, 500 

-.6 

5,100 

-2.4 

22,000 

-4.5 

3,200 

-1.7 

2, 700 

-1.4 

2, 500 -1.3 

5,100 

-2.3 

2, 200 -1.1 

340 

1.6 

1,300 

-.4 

2, 200 

-1.1 

1,600 

-0.7 

1,300 

-0.4 

1,800 

-0.8 

2,100 

-1.1 

3,800 

-1.9 

1,400 

-0.5 

270 

1.9 

1, 900 

-0.9 

910 

0.1 

1, 700 

-0.8 

2,500 

-1.3 

360 

1. 5 

230 

2.1 

760 

.4 1,100 

-.2 

4,900 

-2.3 

670 

.6 

125 

3.0 

140 

2.9 

1,500 

-.6 

230 

2.1 

220 

2.2 

230 

2.1 

200 

2.4 

7,300 

-2.9 

1, 200 

-0.3 

1,600 

-0.7 

2, 500 

-1.3 

190 

2. 4 

MECHANICS OF AQUIFER SYSTEMS 

TABLE B.-Particle-size data for cored sediments, Tulare-Wasco area-Continued 

Percentiles ( mic;ons) Deviations 

Mode 

(mic;ons) M.; 

I I I I I I I 

QD.; 

I ~ tT.; a.; 

2 5 16 25 (Md) 75 84 95 

Richgrove core-Continued 

2,000 1,300 500 300 70 12 4.9 ------ 35 4.3 3.3 2.3 .15 

-1.0 -0.3 1.0 1.8 3.8 6.4 7. 7 4.8 

2,100 1,100 330 170 35 4.4 1.5 ------ 36 5. 5 3.9 2.6 .16 

-1.1 -0.1 1.6 2.5 4.8 7.8 9.3 4.8 

1,200 620 160 110 51 15 6. 5 1.3 46 5.0 2.3 1.4 .28 

-0.2 0. 7 2. 7 3.2 4.3 6.0 7.3 9.6 4.4 

1,300 850 320 180 39 7.3 2. 7 ------ 34 5.1 3.4 2.3 .12 

-0.4 0.2 1.6 2. 5 4. 7 7.1 8.5 4. 9 

1,200 570 150 96 34 6. 5 1.7 ------ 40 6.0 3.2 1.9 .34 

-0.2 0.8 2. 7 3.4 4. 9 7.3 9.2 4. 7 

1,500 930 420 260 17 2.6 1.2 ------ ------------ 5. 5 4. 2 3.3 -.08 

-0.6 .1 1.3 2.0 5.8 8.6 9. 7 

1, 200 770 280 140 53 12 3. 7 ------ 45 5.0 3.1 1.8 .24 

-.3 .4 1.9 2.8 4. 2 6.3 8.1 4. 5 

3, 700 2,500 1,100 690 240 54 17 1. 3 350 2.9 3.0 1.8 .27 

-1.9 -1.3 -.1 . 5 2.1 4. 2 5.9 9.6 1. 5 

15,000 2, 200 750 450 140 20 3.4 ------ 210 4.3 3.9 2. 2 .37 

-3.9 -1.2 .4 1.1 2. 9 5.6 8.2 2.3 

2,600 2,000 1,000 720 240 76 23 ------ 690 2. 7 2. 7 1.6 .24 

-1.4 -1.0 0 . 5 2.1 3. 7 5.4 .5 

2,200 920 240 130 59 15 5.8 ------ 52 4. 7 2. 7 1. 5 .25 

-1.1 . 1 2.0 2.9 4.1 6.0 7.4 4.3 

2,000 1,300 450 130 22 5.6 2.3 ------ 28 5.0 3.8 2. 2 -.15 

-1.0 -.4 1.1 3.0 5. 5 7. 5 8.8 5. 2 

3,400 2,200 180 84 21 4.9 2.2 ------ 31 5. 7 3.2 2.0 .03 -1.8 -1.1 2. 5 3. 6 5. 6 7. 7 8.8 5.0 

1,600 930 230 150 45 8. 2 3.7 ------ 40 5.1 3.0 2.1 .20 

-.6 .1 2.1 2.8 4. 5 6. 9 8.1 4.6 

180 110 75 61 30 12 6. 5 1. 5 37 5.5 1.8 1. 2 .25 

2. 5 3. 2 3. 7 4.0 5.1 6.4 7.3 9.4 4.8 

900 340 120 82 34 10 3.1 ------ 38 5. 7 2.6 1.5 .32 

.1 1.6 3.1 3.6 4.9 6.6 8.3 4. 7 

690 240 130 80 18 2.6 ------ ------ ------------ -------- -------- 2.5 -------- . 5 2.0 2.9 3.6 5.8 8.6 1,300 930 360 170 16 1. 9 ------ ------ ------------ -------- -------- 3.2 -------- -0.4 0.1 1.5 2. 5 5. 9 9.0 1,000 560 130 45 7.1 1. 5 ------ ------ ------------ -------- -------- 2. 5 -------- 0.0 0.8 3.0 4. 5 7.1 9.4 1,400 880 290 130 40 6. 7 2.3 ------ 57 5.3 3. 5 2.1 .18 

-0.4 0.2 1.8 3.0 4. 6 7.2 8.8 ------ 4.1 

1,600 1,000 410 270 90 11 3.4 ------ 190 4. 7 3. 5 2.3 .37 

-0.7 0.0 1.3 1.9 3. 5 6.5 8.2 ------ 2.4 

2,800 1, 700 620 290 93 22 8. 7 1.0 50 3.8 3.1 1.8 .11 -1.5 -0.8 .7 1.8 3.4 5. 5 6.8 10.0 4.3 1,100 660 170 81 14 1.7 ------ ------ ------------ -------- -------- 2.8 -------- -0.1 0.6 2.5 3.6 6.2 9.2 230 190 140 120 72 28 15 1.2 76 4.4 1.6 1.0 .40 

2.1 2.4 2. 8 3.1 3.8 5.1 6.1 9.6 3. 7 1,500 1,100 560 260 95 25 10 1.1 75 3. 7 2. 9 1.7 .11 -0.6 -0.2 .8 1.9 3.4 5.3 6.6 9.9 3. 7 680 420 190 120 42 12 6.4 1.0 37 4.9 2.4 1.7 .11 0. 6 1.2 2.4 3.0 4.6 6.3 7.3 10.0 4.8 1,200 710 310 210 82 20 7. 7 ------ 48 4.4 2. 7 1.7 .28 

-0.3 0. 5 1.7 2.3 3.6 5. 7 7.0 4.4 1,800 1,300 710 510 170 28 11 ------ 410 3. 5 3.0 2.1 .32 

-0.9 -0.4 .5 1.0 2.6 5.2 6.6 ------ 1.3 280 210 150 120 33 7.3 2.9 ------ 150 5.6 2.8 2.0 .23 

1.8 2.2 2.8 3.0 4.9 7.1 8.4 2. 7 220 180 90 55 7.2 3.0 2.4 1.5 ------------ 6.1 2.6 2.1 -.39 

2.2 2.5 3.5 4.2 7.1 8.4 8. 7 9.4 670 540 270 150 5.3 ------ ------ ------ ------------ -------- -------- -------- -------- .6 .9 1. 9 2. 7 7.6 800 470 200 140 31 4.3 1.6 ------ ------------ 5.8 3.5 2.5 .23 

.3 1.1 2.3 2.9 5.0 7.9 9.3 3,400 2,100 200 100 37 7.4 3.1 ------ 41 5.3 3.0 1.9 .19 

-1.8 -1.1 2.3 3.3 4.8 7.1 8.3 4.6 

550 380 130 20 2. 7 ------ ------ ------ ------------ -------- -------- -------- -------- .9 1.4 2.9 5.6 8.5 92 58 30 21 11 3.6 1. 7 ------ 23 7.1 2.1 1.3 .27 

3.4 4.1 5.1 5.5 6.6 8.1 9.2 5.4 

110 81 50 38 22 9.1 4. 7 ------ 32 6.0 1.7 1. 0 . 31 

3.2 3.6 4.3 4. 7 5.5 6.8 7. 7 4.9 

1,200 870 480 280 130 19 1. 0 ------ 170 5.5 4.5 2.0 .57 

-.3 .2 1.1 1.8 3.0 5.8 10.0 2.6 

210 150 82 62 29 12 6.8 2.4 35 5.4 1.8 1.2 .16 

2.3 2. 7 3.6 4.0 5.1 6.4 7.2 8. 7 4.8 

130 71 32 22 10 3.6 1. 7 ------ 22 7.1 2.1 1.3 .23 

2.9 3.8 5.0 5.5 6.6 8.1 9.2 5.5 210 160 61 28 4.6 ------ ------ ------ ------------ ---------- ----- -------- -------- 2.3 2. 7 4.0 5.2 7.8 170 140 97 76 38 16 10 4.2 41 5.0 1.6 1.1 .15 

2. 5 2. 8 3. 4 3. 7 4. 7 5.9 6.6 7. 9 4. 6 

6,100 4,600 2, 700 2,100 680 270 130 2. 7 630 . 7 2.2 1.5 .08 

-2.6 -2.2 -1.4 -1.0 .fi 1.9 2.9 8.5 0. 7 

880 550 240 170 36 2. 5 ------ ------ 170 -------- -------- 3.0 -------- .2 .9 2.1 2.6 4.8 8.6 2. 5 1,100 590 180 88 19 2.2 ------ ------ 32 -------- -------- 2. 7 -------- -0.1 0.8 2. 5 3. 5 5. 7 8.8 4. 9 

1, 700 870 340 230 74 14 2.6 ------ 42 5.1 3. 5 2.0 .38 

-0.8 .2 1.5 2.1 3. 8 6.2 8.6 ------ 4.6 

170 140 85 55 10 1.3 ------ ------ ------------ -------- -------- 2. 7 ................. 

2. 5 2. 8 3.6 4.2 6.6 9.6 

Skewness 

Skq.; Skq.; QD.; 

.10 .24 

.13 .34 

.20 .29 

.05 .11 

.23 .45 

-.17 -.58 

.20 .35 

.17 .31 

.23 . 52 

.03 .05 

.26 .39 

-.13 -.29 

.02 .05 

.18 .37 

.11 .12 

.15 .23 

.14 .35 

-.04 -.14 

-.09 -.21 

.22 .46 

. 31 .71 

.11 .20 

.07 .20 

.30 .32 

.13 .21 

.06 .10 

. 21 .36 

.25 .53 

.06 .12 

-.40 -.84 

---------- --------

.15 .37 

.20 .39 

---------- --------

.20 .26 

.23 .24 

.42 .82 

.06 .08 

.17 .22 

---------- --------

.09 .10 

-.09 -.14 

.26 .78 

.17 .45 

.19 .39 

.08 .23 

Finer 

than3 

micron 

(pereent) 

1 2 

22 

1 

1 

1 9 

1 

1 

1 

1 

1 

1 

1 

1 

27 

5 

8 

6 

0 

2 

8 

9 

4 

9 

6 

27 

30 

3tl 

1 

1 

1 

8 

5 

9 

33 

7 

8 

0 

9 

9 

1 6 

3 

45 

22 

1 6 

5 

1 

22 

2 

9 

8 

1 

22 

43 

4 

2 5 

8 

6 

2 

1 

3 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C63 

Depth 

below 

Sample land 

surface 

(feet) 

59 CAL 397 _____ 1,363 

59 CAL 398 .. ___ 1,370 

59 CAL 399 _____ 1,421 

59 CAL 400. ____ 1,431 

59 CAL 40L. ___ 1,447 

59 CAL 402 _____ 1,492 

59 CAL 403 _____ 1, 527 

59 CAL 404 _____ 1,688 

59 CAL 405 _____ 1, 721 

59 CAL 406 _____ 1, 752 

59 CAL 407 _____ 1, 785 

59 CAL 408 _____ 1,803 

59 CAL 409 _____ 1,814 

59 CAL 410 _____ 1,827 

59 CAL 411 _____ 1,892 

59 CAL 412 _____ 1, 912 

59 CAL 413 _____ 1,943 

59 CAL 414 _____ 1,956 

59 CAL 415 _____ 1,964 

59 CAL 416 _____ 2, 010 

59 CAL 417 _____ 2, 051 

59 CAL 418 _____ 2,102 

59 CAL 419 _____ 2,174 

Depth 

below 

Sample land 

surface 

(feet) 

60 CAL 10 ______ 37 

60 CAL 11------ 50 

60 CAL 12------ 72 

60 CAL 13 ______ 91 

60 CAL 14------ 101 

60 CAL 15------ 113 

60 CAL 16 ______ 121 

60 CAL 17------ 131 

60 CAL 18- _____ i41 

60 CAL 19 ______ 151 

60 CAL 20 ______ 160 

60 CAL 21__ ____ 178 

TABLE 8.-Particle-size data for cored sediments, Tulare-Wasco area-Continued 

Percentiles (microns) 

Deviations 

Mode 

<P 

(mic;ons) M<t> 

I I I I I I I I 

QD<t> 1 50 tT<f> a.q, 

(C) 2 5 16 25 (Md) 75 84 95 

Richgrove core-Continued 

240 230 190 100 60 18 4.4 ------ ------ 31 -------- -------- 1.9 -------- 2.1 2.2 2.4 3.3 4.1 5.8 7.8 5.0 

950 650 430 290 230 130 14 2.0 ------ 190 5.4 3.6 2.0 0. 70 

.1 .6 1.2 1.8 2.1 2.9 6.2 9.0 2.4 

1,300 1,100 870 610 520 220 4. 7 ------ ------ 530 -------- -------- 3.4 -------- -0.4 -0.1 .2 . 7 1.0 2.2 7. 7 0.9 

1,800 1,600 1,200 680 530 150 6.2 1.1 ------ 680 5.2 4.6 3.2 .53 

-0.9 -0.7 -0.3 .6 .9 2. 7 7.3 9.8 0. 5 

200 180 150 100 56 15 2.2 ------ ------ 33 -------- -------- 2.3 -------- 2.3 2. 5 2. 7 3.3 4.2 6.0 8.8 4. 9 

1,400 1,100 690 380 300 150 48 6. 5 ------ 260 4.3 2. 9 1.3 .53 

-0.4 -0.1 . 5 1.4 1.7 2.8 4.4 7.3 1.9 

240 230 190 100 56 14 1.8 ------ ------ 31 -------- -------- 2.5 -------- 2.1 2.1 2.4 3.3 4.1 6.2 9.1 5.0 

230 210 170 130 85 10 1.3 ------ ------ ------------ -------- -------- 3.0 -------- 2.1 2.3 2. 5 2. 9 3.6 6.6 9.6 

250 240 230 200 170 100 26 11 2.8 160 4.4 2.0 1.4 .54 

2. 0 2. 0 2.1 2.4 2.6 3.3 5.3 6. 4 8. 5 2. 6 

6,600 5,400 3,800 210 160 85 22 6.4 1. 5 120 4. 8 2. 5 1.4 .49 

-2.7 -2.4 -1.9 2.3 2. 6 3. 5 5. 5 7.3 9. 4 3. 0 

760 610 430 240 200 110 29 16 4.3 180 4. 0 2. 0 1.4 .45 

.4 . 7 1. 2 2. 0 2. 4 3.1 5.1 6. 0 7. 9 2.5 

1,600 1,300 870 370 220 96 33 14 ------ 83 3.8 2.3 1.4 .17 

-.7 -.4 .2 1.4 2. 2 3.4 4. 9 6.1 3.6 

4,000 3,200 2,200 1,100 670 190 83 55 3. 7 99 2. 0 2.1 1.5 -.15 

-2.0 -1.7 -1.2 -.1 .6 2.4 3.6 4. 2 8.1 3.3 

210 190 160 130 89 15 3.8 2. 7 1.4 150 5. 7 2.8 2.3 -.10 

2.3 2. 4 2.6 2.9 3.5 6.0 8.1 8.5 9.5 2. 7 

210 200 170 140 130 38 5.3 3. 7 2. 5 160 5.4 2.6 2.3 .27 

2. 2 2.4 2. 5 2.8 3. 0 4. 7 7.6 8.1 8. 7 2.6 

540 410 270 120 100 75 27 7.3 ------ 75 5.1 2. 0 1. 0 .66 

.9 1.3 1.9 3.1 3.3 3. 7 5. 2 7.1 3. 7 

420 370 300 220 200 150 110 83 51 170 2.9 . 7 .4 . 20 

1. 2 1.4 1. 7 2.2 2.3 2. 7 3. 2 3.6 4. 3 2.6 

2,300 1,900 1,500 990 810 540 330 250 120 610 1.0 1.0 .7 .11 

-1.2 -.9 -.6 .0 .3 .9 1.6 2. 0 3. 0 .7 

3,200 2, 700 2,100 1,400 1,100 710 360 210 65 820 .9 1.4 .8 .30 

-1.7 -1.4 -1.0 -.5 -.2 .5 1.5 2.3 3.9 .3 

2,500 2,100 1, 700 1,200 1,100 730 500 300 90 780 .7 1. 0 .6 . 25 

-1.3 -1.1 -.8 -.3 -.1 .5 1. 0 1. 7 3. 5 3.4 

3,500 3, 000 2,300 1,300 990 330 180 150 67 210 1. 2 1.6 1. 2 -.27 

-1.8 -1.6 -1.2 -.4 .0 1.6 2.4 2. 8 3. 9 2. 3 

14,000 11,000 7,300 3,800 2,800 1,300 310 180 71 2,200 .3 2. 2 1. 6 .30 

-3.8 -3.5 -2.9 -1.9 -1.5 -.4 1. 7 2. 5 3. 8 -1.1 

1,400 1,200 930 520 410 250 150 110 35 270 2.1 1.1 .7 .09 

-.5 -.3 .1 .9 1.3 2. 0 2. 7 3.2 4.8 1.9 

TABLE 9.-Particle-size data for cored sediments, Santa Clara Valley 

[Particle-size analyses made by the Hydrologic Laboratory of the U.S. Geological Survey, Denver, Colo.] 

. (microns) Deviations 

Percentiles --<P- Mode 

(mic;ons) M<t> 

I I I I I ,:d) I I I 

QD<t> 1 tT<f> Ct.<f> 

(C) 2 5 16 25 75 84 95 

Sunnyvale core 

2,000 620 290 130 88 33 7. 7 2.2 ------ 40 5.9 2. 9 1.8 0.34 

-1.0 0. 7 1.8 3.0 3. 5 4.9 7.0 8.9 4. 7 4,000 1,400 200 69 39 11 1.0 ------ ------ ------------ -------- -------- 2.6 

-2.0 -0.5 2.3 3.9 4. 7 6.5 10.0 

210 180 150 75 44 12 1.8 ------ ------ 32 -------- -------- 2.3 

2.3 2. 5 2.8 3. 7 4. 5 6.3 9.1 5.0 

200 140 79 21 11 3.1 ------ ------ ------ ------------ -------- -------- -------- -------- 2.3 2.8 3. 7 5.6 6.4 8.4 

150 98 45 19 13 4.8 1.2 ------ ------ ------------ -------- -------- 1.7 -------- 2.8 3.3 4. 5 5. 7 6.3 7. 7 9. 7 140 70 28 7.0 4.6 1.9 ------ ------ ------ ------------ -------- -------- -------- -------- 2. 9 3.8 5.2 7.2 7.8 9.1 42 30 18 9.3 6.6 2.9 1.0 ------ ------ ------------ -------- -------- 1.3 

4.6 5.1 5. 8 6. 7 7.2 8.4 9.9 

170 140 94 46 31 14 4.6 1.9 ------ 29 6.8 2.3 1.4 .24 

2.6 2. 9 3.4 4.4 5.0 6.2 7.8 9.1 5.1 

9,800 4,900 290 75 35 5.1 ------ ------ ------ ------------ -------- -------- -------- -------- -3.3 -2.3 1.8 3. 7 4.9 7.6 170 140 62 15 8.8 2.9 ------ ------ ------ ..,.., __________ __ ... _____ -------- -------- -------- 2.6 2. 9 4.0 6.0 6.8 8.4 

83 51 29 12 8. 5 2.8 ------ ------ ------ ------------ -------- -------- -------- -------- 3.6 4.3 5.1 6.3 6.9 8. 5 

Skewness 

Skq<t> 

QD<t> 

0.10 

.62 

.63 

.43 

.20 

.23 

.18 

.00 

.46 

.37 

. 44 

.13 

-.19 

-.11 

.23 

.53 

.13 

.11 

.18 

. 02 

-.31 

. 31 

. 05 

Skewness 

Skq<t> 

QD<t> 

0.20 

.31 

.20 

----------

.18 

----------

.13 

.12 

----------

----------

----------

180 160 130 53 28 7.2 ------ ------------ -------- -------- -------- -------- ---------- ------ ------ 2.4 2. 7 3.0 4.2 5.1 7.1 

Finer 

than 3 

micron 

Skq<t> (percent) 

0.18 23 

1.27 1 

2.12 22 

1.38 21 

.47 2 8 

.30 1 

.45 2 8 

-.01 31 

. 63 5 

. 53 1 0 

.60 4 

.18 1 0 

-.29 4 

-.24 20 

. 53 20 

.51 13 

.06 3 

. 07 1 

.15 1 

. 01 1 

-.37 1 

. 49 1 

.04 1 

Finer 

than 3 

micron 

Skqq, (percent) 

0.35 17 

.81 33 

.47 28 

-------- 51 

.30 40 

-------- 63 

.17 49 

.17 20 

-------- 43 

-------- 50 

-------- 53 

-------- 26 
C64 

Sample 

0 CAL 22.. ____ 

0 CAL 23 ______ 

0 CAL 24 ______ 

0 CAL 25 ______ 

0 CAL 26 ______ 

0 CAL 27------

0 CAL 28 ______ 

0 CAL 29 ______ 

0 CAL ao ______ 

0 CAL 31._ ____ 

0 CAL 32 ______ 

0 CAL 33 ______ 

0 CAL 34 ______ 

0 CAL 35 ____ --

0 CAL 36 ______ 

0 CAL 37 ______ 

0 CAL as ______ 

0 CAL 39 ______ 

0 CAL 40 ______ 

0 CAL 41._ ____ 

0 CAL 42 ______ 

CAL 43 ______ 

0 CAL 44 ______ 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

6 

60 

6 

60 

6 

6 

6 

60 

60 

60 

60 

60 

60 

60 

6 

60 

60 

60 

6 

6 

60 

6 

6 

60 

60 

60 

CAL 45 ______ 

0 CAL 46 ______ 

0 CAL 47 ______ 

0 CAL 48 ______ 

CAL 49 ______ 

CAL 50 ______ 

CAL 51_ _____ 

CAL 52 ______ 

CAL 53 ______ 

CAL 54 ______ 

CAL 55 ______ 

0 CAL 56 ______ 

CAL 57 ______ 

CAL 58 ______ 

CAL 59 ______ 

0 OAL 60 ______ 

0 CAL 6L _____ 

CAL 62 ______ 

0 CAL 63 ______ 

0 CAL 64 ______ 

CAL 65 ______ 

CAL 66 ______ 

CAL 67 ______ 

Depth 

below 

land 

surface 

(feet) 1 

(C) 

192 2,300 

-1.2 

210 220 

2.2 223 75 

3. 7 229 2,800 

-1.5 236 2,900 

-1.6 254 2,000 

-1.0 307 140 

2.8 313 560 

0.8 330 280 

1.8 345 240 

2.1 362 4, 700 

-2.2 409 340 

1.6 420 830 

0.3 432 460 

1.1 437 8,000 

-3.0 446 1,600 

-0.6 459 210 

2.3 463 220 

2.2 523 810 

Oo3 545 160 

2.6 555 1, 700 

-0.7 563 460 

1.1 575 220 

2.2 606 2,400 

-1.3 634 370 

1.4 657 380 

1.4 666 8,000 

-300 716 330 

1.6 736 350 

1.5 745 160 

206 757 160 

2.6 773 180 

2. 5 790 250 

2.0 797 240 

2.1 812 160 

2. 7 824 67 

30 9 836 400 

1.3 842 40 

4.6 854 140 

208 866 62 

4.0 874 190 

2.4 883 310 

1.7 900 250 

2.0 910 150 

2.8 924 160 

2.6 937 300 

1.8 

MECHANICS OF AQUIFER SYSTEMS 

TABLE 9.-Particle-size data for cored sediments, Santa Clara Valley-Continued 

Percentiles ( mic;ons) 

Deviations Skewness 

Mode Finer 

thana 

(mic;ons) M<t> micron 

I I I I I I I 

QD<t> Skq<t> Skq<t> (perI .. U<f> a<!> QD<t> cent) 2 5 16 25 (Md) 75 84 95 

Sunnyvale Core-Continued 

880 230 82 40 7.6 ------ ------ ------ ------------ -------- -------- -------- -------- _____ .... ____ -------- 39 

1.8 2.1 3.6 4.6 7.0 190 120 77 61 27 7. 7 3.0 ------ 37 6.0 2.3 1. 5 0.35 0.21 0.31 16 

2.4 3.0 3. 7 4.0 5.2 7.0 8.4 ------ 4.8 

48 28 13 9.0 3. 7 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 44 4.4 5.2 6.3 6.8 8.1 410 220 120 81 27 6.1 2.6 ------ 39 5.8 2.8 1. 9 .23 .15 .28 17 

1.3 2.2 3.1 3.6 5. 2 7.4 8.6 4. 7 2,300 320 130 79 21 4.6 1.8 ------ 33 6.0 3.1 2.1 .15 .09 .17 20 

-1.2 1.6 2.9 3. 7 5. 5 7.8 9.1 4.9 250 170 93 66 27 6. 7 3.1 ------ 37 5.9 2.5 1. 7 .27 . 21 .34 15 

2.0 2.5 3.4 3.9 5.2 7. 2 8.3 4.8 97 59 29 20 7.2 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 34 

3.4 4.1 5.1 5.6 7.1 370 180 42 24 7.4 1.3 ------ ------ ------------ -------- -------- 2.1 -------- .19 .40 33 

1.4 2.5 4.6 5.4 7.1 9.6 210 150 53 29 6.6 1.5 ------ ------ 31 -------- -------- 2.1 -------- .00 .00 35 

2.3 2.8 4.3 5.1 7.2 9.4 5.0 

200 150 79 52 20 3.4 1.1 ------ 34 60 7 3.1 2.0 .35 o30 0 59 24 

2.3 2. 7 3. 7 4.3 5. 7 8.2 9.8 4.9 2,800 420 130 43 8. 5 1.6 ------ ------ ------------ -------- -------- 2.4 -------- .02 .04 33 

-1.5 1.2 3.0 4.6 6.9 9.3 190 110 39 22 6.9 1.0 ------ ------ ------------ -------- -------- 2.3 -------- .24 . 55 37 

204 3.2 4. 7 5.4 7.2 10o0 470 260 150 110 33 5.9 1. 5 ------ 44 6.1 3.3 2.1 .35 .19 .40 19 

1.1 2.0 2. 7 3.2 40 9 7.4 9.4 4. 5 360 240 130 77 21 2.6 ------ ------ ------------ -------- -------- 2. 5 -------- .22 . 55 26 

1.5 2.0 3.0 3. 7 5.6 8.6 1,500 410 170 110 22 2o9 ------ ------ ------------ -------- -------- 2.6 -------- .13 .33 25 

-0.6 1.3 2.5 3.2 5.5 8.4 1,200 640 180 64 6. 7 1.6 ------ ------ ------------ -------- -------- 2. 6 -------- -.23 -.61 33 

-0.3 0.6 2.5 4.0 7.2 9.2 160 110 53 36 15 3.6 ------ ------ 30 -------- -------- 1. 7 -------- .26 .43 23 2.6 3.2 4.2 4.8 6.0 8.1 5.1 

200 160 130 92 36 4.2 1.1 ------ 50 6.4 3.4 2. 2 .47 .39 .86 23 

204 2.6 3.0 3.4 4.8 7.9 9.8 4.3 640 410 130 57 11 1.4 ------ ------ ------------ -------- -------- 2. 7 -------- .10 .27 31 

0.6 1.3 2.9 4.1 6.5 9.4 130 86 37 24 8.9 1. 7 ------ ------ 27 -------- -------- 1.9 -------- .26 .49 31 

2.9 3.5 4. 7 5.4 6.8 9.2 5.2 

1,100 330 140 97 33 4o 7 ------ ------ 41 -------- -------- 2.2 -------- o30 .65 23 

-0.2 1.6 2.8 3.4 4.9 7o 7 4.6 

330 200 60 32 7.9 1o 2 ------ ------ ------------ -------- -------- 2.4 -------- .16 .37 35 

1.6 2.3 4.1 5.0 7.0 9o 7 150 80 33 22 8.0 1. 7 ------ ------ 27 -------- -------- 1.8 -------- .20 .37 33 

2. 8 3. 6 4.9 5. 5 7. 0 9. 2 5.2 

1,100 390 140 80 16 10 3 ------ ------ ------------ -------- -------- 3.0 -------- .23 .69 31 

-1.0 1.4 2. 9 3.6 5. 9 9o6 280 210 140 110 28 2. 9 ------ ------ ------------ -------- -------- 2.6 -------- .27 .69 25 

1.8 2.3 2.8 3.2 5.1 8o4 280 200 120 68 8. 7 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 37 

1.8 2.3 3.0 3.9 6.8 460 120 77 63 19 300 ------ ------ 42 -------- -------- 2.2 -------- .23 .50 25 

1.1 3.1 3. 7 4.0 5. 7 804 4.6 240 140 39 19 3.4 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 48 

2.1 2.8 4. 7 5. 7 8.2 290 210 120 79 24 2.1 ------ ------ 39 -------- -------- 206 -------- .35 .92 26 

1.8 2.2 3.1 3. 7 5.4 8o 9 4. 7 

110 69 20 11 2.8 ------ ------ ------ ------------ -------- -------- -------- -~------ ---------- -------- 53 

3.2 3. 9 5. 7 6. 5 8. 5 130 80 21 9.3 1.8 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 59 

2.9 3. 7 5.6 6.8 9.2 140 62 26 17 7. 7 2.6 1.4 ------ 16 7.4 2.1 1.4 .16 .14 .19 27 

2.8 4.0 5.3 5o 9 7.0 8.6 9.5 ------ 6.0 

100 63 17 10 3o 7 1.1 ------ ------ ------------ -------- -------- 1.6 -------- .08 .13 45 

3.3 4.0 6.0 6.6 8.1 9.9 210 180 130 110 66 25 12 ------ 68 4.6 1.7 1.1 .42 .33 .35 9 

2.2 2. 5 2.9 3.2 3. 9 5.3 6.3 3.9 125 91 48 29 7.2 1. 4 ------ ------ 33 -------- -------- 2.2 -------- o08 .18 36 

3.0 3. 5 4.4 5o1 7.1 9. 5 4.9 

54 40 25 20 8. 5 1o8 ------ ------ 28 -------- -------- 1.7 -------- .29 .50 32 

4.2 4.6 5.3 5o6 6. 9 9.1 5.2 360 310 240 210 160 130 80 600 180 2. 9 .8 04 .30 .00 .00 4 

1.5 1.7 2.1 2.2 2.6 300 3.6 7.4 2. 5 32 23 13 9. 7 4.1 1.1 ------ ------ ------------ -------- -------- 1. 6 -------- 0 21 .34 41 

5.0 5o4 6.2 6. 7 7. 9 9o 8 84 28 8. 5 502 1.9 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 63 

3o6 5o1 6. 9 7.6 9.1 32 13 6.4 4.4 1.8 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 64 

5.0 6.2 7.3 7.8 9.2 170 140 72 44 10 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 36 

2.6 2.9 3.8 4.5 6.6 250 170 70 43 15 1.2 ------ ------ 33 -------- -------- 2.6 -------- .40 1.03 31 

2.0 2.6 3.8 4. 5 6.1 9. 7 4. 9 190 120 27 11 2.3 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 56 

204 3.1 5.2 6. 5 8.8 110 52 17 8.1 2.6 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 55 

302 4.3 5o9 6.9 8.6 98 34 7.5 3. 7 1.3 ------ ------ ------ ------------ -------- -------- -------- -------- ·--------- -------- 72 

3.3 4. 9 7.1 8.1 9.6 220 120 22 8.6 .8 ------ ------ ------ ------------ -------- -------- -------- -------- ---------- -------- 65 

2.2 3.1 5.5 6.9 10.3 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C65 

TABLE 9.-Particle-size data for cored sediments, Santa Clara Valley-Continued 

Percentiles ( mic;ons) Deviations Skewness Depth Mode Finer below than 3 Sample land 

(mic;ons) M~ micron surface 

I I I I I (:d) I I I QD~ Skq., Skq~ (per- u~ a~ (feet) 1 QDo~> cent) 2 5 16 25 75 84 95 (C) 

Sunnyvale core-Continued 

60 CAL 68 ______ 959 220 150 110 71 48 8.0 

2.2 2. 7 3.2 3.8 4.4 7.0 

60 CAL 69 ______ 967 1,000 460 220 43 25 6.1 

.0 1.1 2.2 4.5 5.3 7.3 

1.1 ------ ------ ------------ -------- -------- 9.9 

------ ------ ------ ------------ -------- --------

2. 7 -------- 0.06 

-------- -------- ----------

0.15 

--------

38 

41 

San Jose core 

60 CAL 70 ______ 197 430 320 220 120 60 6.2 ------ 1.2 1.6 2.2 3.1 4.1 7.3 60 CAL 71__ ____ 207 120 110 92 70 61 21 5.6 

3.0 3.2 3.4 3.8 4.0 5.6 7.5 60 CAL 72 ______ 233 170 125 66 26 17 5.4 1.3 

2.5 3.0 3.9 5.3 5.9 7.5 9.6 60 CAL 73 ______ 258 12,000 8,300 400 78 48 12 ------ -3.5 -3.0 1.3 3. 7 4.4 6.4 60 CAL 74 ______ 276 470 320 180 70 44 16 3.5 

1.1 1.6 2.5 3.8 4.5 6.0 8.2 60 CAL 75 ______ 301 4,000 690 220 95 58 19 2.0 

-2.0 .5 2.2 3.4 4.1 5. 7 9.0 

60 CAL 76 ______ 324 2,800 1,000 630 410 360 270 170 

-1.5 .0 .7 1.3 1.5 1.9 2.5 60 CAL 77 ______ 334 67 49 31 15 11 4.4 1.0 

3.9 4.3 5.0 6.0 6.5 7.8 10.0 60 CAL 78 ______ 355 290 230 190 130 110 52 17 

1.8 2.1 2.4 2.9 3.2 4. 3 5. 9 60 CAL 79 ______ 402 42 34 26 16 10 3.4 ------ 4.6 4.9 5.3 6.0 6. 6 8. 2 60 CAL so ______ 430 560 390 240 120 71 18 2. 2 0.8 1.4 2.1 3.0 3.8 5.8 8.8 60 CAL 8L ____ 441 740 540 390 250 200 130 63 

0.4 o. 9 1. 3 2.0 2. 3 2.9 4. 0 60 CAL 82 ______ 510 8, 500 6,000 2, 900 190 110 24 1. 8 

-3.1 -2.6 -1.5 2.4 3. 2 5.4 9.1 60 CAL 83 ______ 531 2, 700 1,000 390 150 90 25 2.4 

-1.5 0.0 1.3 2. 7 3. 5 5.3 8. 7 60 CAL 84 ______ 555 1,400 830 420 200 140 39 6.6 -0.5 o. 3 1. 3 2. 3 2. 9 4. 7 7.3 60 CAL 85 ______ 570 500 370 240 130 89 32 7.1 

1.0 1.4 2.1 2.9 3. 5 5.0 7.1 60 CAL 86 ______ 599 6,800 4,800 1,400 230 160 51 10 

-2.8 -2.3 -0.5 2.1 2.6 4. 3 6. 6 60 CAL 87 ______ 697 4,000 2,300 390 110 56 14 2.3 

-2.0 -1.2 1. 4 3. 2 4. 2 6. 1 8. 8 60 CAL 88 ______ 705 5,400 3,800 2,300 610 390 160 24 -2.4 -1.9 -1.2 0. 7 1. 4 2. 7 5.4 60 CAL 89 ______ 725 1,200 720 270 88 48 12 ------ -0.3 0. 5 1.9 3.5 4.4 6.4 60CAL9o ______ 750 27,000 23,000 15,000 8,500 5, 700 1,500 470 

-4.8 -4.5 -3.9 -3.1 -2.5 -0.6 1.1 60 CAL 9L _____ 791 1,200 410 220 100 69 22 3.6 

-0.2 1. 3 2.2 3.3 3.9 5. 5 8.1 60CAL92 ______ 812 170 140 110 61 44 22 7. 8 

2.5 2.8 3. 2 4. 0 4.5 5. 5 7.0 60 CAL 93 ______ 833 250 200 140 74 51 19 4.4 

2. 0 2.3 2.9 3.8 4.3 5. 7 7.8 60 CAL 94 ______ 848 220 180 140 74 52 23 6. 5 

2.2 2. 5 2. 9 3. 7 4.3 5.4 7.3 60 CAL 95 ______ 909 320 230 150 '69 43 16 3.1 

1.6 2.1 2. 7 3.9 4.5 6. 0 8.3 60 CAL 96. _____ 938 4i0 330 190 62 37 11 1.5 

1.1 1.6 2. 4 4. 0 4.8 6. 5 9.4 

ANALYTICAL PROCEDURES AND TABULATED RESULTS 

OF CLAY-MINERAL STUDY 

CLAY -MINERAL SEPARATION 

As an aid to the study of clay minerals, material 

coarser than 2p. is removed from a sediment in order that 

the characteristics of the clay minerals may be observed 

more clearly. Three different but similar procedures 

were used to separate the <2p. fractions of the sediments discussed in this report. The first procedure 

was used in the Sedimentary Petrology Laboratory of 

the Geological Survey to separate the clay minerals from 

25 samples from the Mendota and Huron cores of the 

------ ------ ------------ -------- -------- --------

2.1 ------ 42 6.3 2.5 1. 7 8.9 4.6 

------ ------ ------------ -------- -------- 1.8 

------ ------ ------------ -------- -------- --------

1.0 ------ 30 6.9 3.1 1.8 

10.0 5.0 

------ ------ 34 -------- -------- 2.4 

4.9 

140 33 300 2.1 .8 .5 

2.9 4.9 1.7 

------ ------ ------------ -------- -------- 1.7 

4.4 ------ 50 5.4 2.5 1.3 

7.8 4.3 

------ ------ ------------ -------- -------- --------

------ ------ 34 -------- -------- 2. 5 

4.9 

25 1.1 170 3. 7 1.7 .8 

5. 3 9.9 2.6 

------ ------ ------------ -------- -------- 3.0 

------ ------ 35 -------- -------- 2.6 

4. 9 

1.1 ------ 37 6.1 3.8 2. 2 9.9 4. 8 

1. 5 ------ 37 6.1 3. 2 1.8 

9.4 4.8 

2.1 ------ 38 5. 5 3.4 2.0 

8. 9 4.7 

------ ------ 31 -------- -------- 2.3 

5.0 

5.9 ------ 290 4.1 3.3 2.0 

7.4 1.8 

------ ------ ------------ -------- -------- --------

310 51 640 -.7 2.4 1.8 

1. 7 4.3 0.6 

1.4 ------ 37 6.4 3.1 2.1 

9. 5 ------ 4.8 

3.3 ------ 33 6.1 2.1 1.3 

8. 2 ------ 4. 9 

1. 5 ------ 33 6.6 2.8 1.8 

9.4 ------ 4.9 

2.2 ------ 34 6.3 2. 5 1.5 

8.8 ------ 4.9 

1.0 ------ 3.2 6.9 3.1 1.9 

10.0 ------ 5. 0 

------ ------ 30 -------- -------- 2.3 

------ ------ 5.1 

-------- ----------

0.31 0.10 

-------- .11 

-------- ----------

.31 .20 

-------- .34 

.21 .19 

-------- .27 

.45 .23 

-------- ----------

-------- . 22 

.46 .28 

-------- .27 

-------- .30 

.38 .16 

.36 .19 

.36 .17 

-------- .14 

.41 .35 

-------- ----------

-.03 -.05 

.28 . 22 

.30 .20 

.29 .18 

. 34 . 22 

.30 .23 

-------- .26 

--------

0.18 

. 21 

--------

.36 

.84 

.10 

.46 

.30 

--------

.54 

.24 

. 79 

. 78 

. 35 

.35 

.33 

.33 

. 70 

--------

-.09 

.47 

. 25 

.32 

.33 

.43 

.60 

4 5 

1 9 

3 

33 

23 

2 

4 

4 

1 4 

4 

2 

1 

2 

28 

26 

9 

0 

1 

2 

1 

3 

2 

1 

3 

5 

22 

1 

2 

3 

Los Banos-Kettleman City area. It is described by 

Hathaway (1956). The second procedure was used on 

the other 76 samples from the Los Banos-Kettleman 

City area. The third procedure, which improved on the 

second, was used to separa1te the clay minerals from sediments of the Tulare-Wasco, Santa Clara Valley, and 

Arvin-Maricopa areas. 

The procedure used on most of the samples from the 

Los Banos-Kettleman City area is as follows. Twenty 

grams of air-dry fine sediment was1. Ground with a wooden pestle in ·a porcelain dish, 

2. Pl'aced in 200-300 ml of 0.05-0.1N sodium hexametaphosphate 

( Calgon) solution, 
C66 MECHANICS OF AQUIFER SYSTEMS 

3. Stirred for 5-10 minutes with a glass rod and left standing 

for severo! days, 

4. Stirred mechanically on a Hamilton Beach milkshake machine 

fur 1 minute, and 

5. Poured through a 23()-mesh (U.S. Standard) sieve, and centrifuged to splirt off material ooarser than 2JL. 

6. The material finer than 2p.. was centrifuged until all material 

c01arser than 0.2JL had been removed from the suspension. 

7. The concentrated 0.2p.-2.0JL fraction was p}aced on glass slides 

(26X45 mm) on which irt dried at room temperature and 

formed oriented aggregates. 

8. The aggregates were placed in the X-ray diffractometer for 

idenltification of the clay minerals. 

The high concentvation of sodimn hexametaphosphate 

used in step 2 is not recommended for general use because in some samples (especially those from streams 

and near-surface alluvial-fan deposits) it provided 

enough sodium to replace the exchangeable calcium and 

magnesium that had been adsorbed by the clay minerals 

in their natural state. This made it impossible to draw 

inferences about the original adsorbed c:ati1ons from the 

X-ray diffraction pattern. The dispersing effect of 

sodium hexametaphosphate seems to be time dependent: 

samples that were allowed to soak in the solution for a 

few days dispersed more readily than samples that had 

soaked in the solution for only a few hours. No dispers· 

ing agent was added to the samples from the Tulare· 

'Vasco area, Arvin-Maricopa area, and Santa Cla.ra Valley; these sedi·ments were dispersed in an ultrasonic 

generator. 

Material finer than 0.2p.. usually was discarded without being analyzed. This did not seem to introduce 

significant error into the estimates of clay-mineral proportions because, as table 10 shows, the compositions of 

the 0.2p..-2.0p. fraction and a finer fraction, O.lp..-0.2p.., 

in selected samples, do not differ significantly. More 

detailed study of the sediments in the Tulare-Wasco 

area and the Santa Clara Valley, however, indicates 

that the differences between the two size fractions may 

be significant-the principal difference being a slightly 

greater proportion of montmorillonite in the finer clay 

fraction. In spite of this, the proportion of the clay 

minerals in the 0.2p..-2.0p.. fraction probably represents 

the proportions of t:he day minerals in the sediments as 

a whole because (1) the blilk of the day minerals is 

found in this size fraction and ( 2) the greater proportion of montmorillonite in the finest clay fraction 

( <0.2p..) is offset by the Jesser proportion in the coarsest 

fraction ( >2.0p.., which was analyzed in a few samples). 

Hathaway (1956, p. 9) and his associates at the Sedimentary Petrology Laboratory avoided the problem by 

recovering all the material finer than 2p.., using a filter 

candle under vacuum to remove water and concentrate 

the clay suspension. 

TABLE 10.-Proportions of clay minerals in two clay-size fractions 

of sediments from Los Banos-Kettleman City area 

Core hole Depth below Size 

land surface fraction 

(feet) (~-<) 

Clay minerals 

(estimated parts per ten) 

-----------1--------------------

Mendota _____ -----------_ 75 o. 2-2.0 7 0 Tr. Tr. 2 D Do ___________________ 75 .1- .2 0 0 1 1 2 D Do ___________________ 551 . 2-2.0 6 0 1 Tr. 2 B Do ___________________ 551 .1- . 2 6 0 1 1 2 D Do ___________________ 981 . 2-2.0 6 0 1 1 2 D Do ___________________ 981 .1- .2 7 0 1 Tr. 2 D Do ___________________ 1,400 .2-2. 0 8 0 Tr. 1 Tr. Do ___________________ 1,400 .1- .2 8 0 Tr. 1 Tr. Cantua Creek ____________ 1, 238 . 2-2.0 6 0 1 Tr. 2 D Do ___________________ 1,238 .1- .2 7 0 2 Tr. 1 D Huron ____________ ------- 470 . 2-2.0 6 0 2 Tr. 2 B Do ___________________ 470 .1- . 2 6 0 1 Tr. 3 D 

Stream 1\faterial 

sampled 

Little Panoche ___________ Suspended __ 0. 2-2.0 2 2 4 0 1 A Do ___________________ ____ do ________ .1- .2 3 2 3 Tr. 2 D 

Panoche ______ ----------- ____ do ________ . 2-2.0 7 0 1 0 2 c Do ___________________ ____ do ________ .1- .2 7 0 1 Tr. 2 c Cantua _____________ ----- ____ do ________ .2-2. 0 7 0 1 0 2 D Do ___________________ ____ do ________ .1- .2 7 0 1 Tr. 2 D 

Salt__ ___________ --------- ____ do ________ .2-2.0 7 0 1 Tr. 2 D Do ___________________ ____ do ________ .1- .2 7 0 1 Tr. 2 D 

1 Letters refer to mineral types shown in fig. 40. 

The procedure used on the samples from the TulareWasco area, the Arvin-Maricopa area, and the Santa 

Clara Valley is as follows. About 5 grams of air-dry 

fine sediment was1. Ground with a wooden pestle in a porcelain dish and 

2. Placed in about 100 ml of distilled water, stirred briefly, and 

left standing overnight. 

3. The sediment was dispersed (no chemical dispersing agent 

was added) by an ultrasonic generator for lh-1 hr. 

4. Concentrated slurries of two size fractions--0.2p.-2.0JL and 

0.1JL-0.2p.-were separated by centrifuging. 

5. Oriented aggregates of the size fractions were made on porous 

ceramic plates ( 26 X 45 mm) , such as those described by 

Kinter and Diamond ( 1956). The slurries were placed 

on the ptat~s with a dropper, and the water was sucked out 

of the slurry, through the pores of the plate, by a vacuum 

pump. 

6. The aggregates, when dry, were placed in the X-ray diffraetometer for identification of the clay minerals. 

Several of the sediments from the Richgrove core 

and all the samples from San Francisco Bay, because 

they contained substantial amounts of soluble salts, flocculated during the centrifuging process. The salts were 

washed from these sediments by repeated decanting 

and centrifuging until the fine-grained material remained dispersed. 

X-RAY DIFFRACTION 

The clay minerals were identified by X-ray diffraction using a N orelco diffractometer and nickel-filtered 

copper radiation. The minimum angular aperture 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C67 

through which the X-ray beam was transmitted was 

1°. The oriented clay aggregates were placed in the 

diffractometer in such a way that the maximum width 

of the sample intersected by the beam was 26 mm (in 

the Los Banos-Kettleman City sediments) or 45 mm (in 

the Tulare-Wasco, Arvin-Maricopa, and Santa Clara 

Valley sediments). Four diffraction patterns were 

made from oriented aggregates of most of the samples, 

as follows: 

1. Air dry, 

2. Treated with glycerol (most of the Los Banos-Kettleman City sediments) or ethylene glycol (TulareWasco, Arvin-Maricopa, and Santa Clara Valley 

sediments) , 

3. Heated to 400° Celsius (centigrade) for 45-60 minutes, and 

4. Heated to 525° C or 550° C for 45-60 minutes. 

Diffraction patterns were also recorded from the 0.2JL2.0JL fractions of samples from the Tulare-Wasco area 

and Santa Clara Valley that had been suspended in 2N 

MgCl2 and 5-10 percent glycerol solution. This is the 

procedure suggested by Walker (1958; 1961, p. 314-

317) for distinguishing between montmorillonite and 

vermiculite. 

IDENTIFICATION OF CLAY MINERALS 

MONTMORILLONITE AND VERMICULITE 

Figure 39 shows X-ray diffraction patterns of two expanding-lattice minerals. The upper row of patterns 

shows a montmorillonite (shaded reflections) whose exchange positions are saturated with sodium. The patAIR-DRY GLYCEROL 

3.5 

3.1-3.2 ~ 

7.1 

7.1 

12.6 

10-14 

3.6 

3.5 3.3 

7.1 

7.1 

9.0 

10 

18.0 

18.0 

14 

3.3 

3.5 

9.9 

10.0 

7.1 

5.0 

FIGt:RE 39.-X-ray diffraction patterns of oriented aggregates of expanding clay minerals. CuKcx radiation: scanning speed 2° per minute. 

Locations of reflections given in Angstrom units. Ordinate is linear intensity. Upper row, Montmorillonite (shaded reflections) from 

sediment suspended in Cantua Creek. Saturated with sodium hexametaphosphate. Lower row, Mixed-layer montmorillonite-illite 

(shaded reflections) from depth of 154 feet in Oro Lorna core hole. Saturated with soduim by treatment with dithionite and sodium 

citrate (Mehra and Jackson, 1960). 
C68 MECHANICS OF AQUIFER SYSTEMS 

terns for air-dry and glycerol-treated montmorillonite 

were made at two different scales to show clearly the 

higher order basal reflections as well as the much 

stronger (001) reflection. The pattern for montmorillonite heated to 400°C was 1nade at the same scale as 

the upper prutterns for air-dry and glyceroltreated montmorillonite. The patterns in the upper 

row of figure 39 also contain reflections ( unshaded) 

from type-B chlorite, a kaolinite-type mineral, illite, 

and quartz. 

Montlnorillonite was identified mainly on the basis 

of X-ray reflections it gave when expanded with organic liquids : 1

an integral series of basal reflections related to 18 A 2 when treated with glycerol, or an integral series related to 17 A when treated with ethylene 

glycol. As recorded in the X-ray diffraction pattern 

(not corrected for 20 angle, t ha~t is) , the intensity 

(area) of the ( 001) reflection a;t 17 or 18 A is 20 or 

more times the intensity of the higher order basal reflections. Air-dry montmorillonite whose exchange positions 1

are occupied by magnesium or calcium gives 

broad basal reflections at 15 and 5 A and a diffuse band 

of reflections in the region between 3.0 and 3.3 A. 

When its exchange positions are occupied by sodium, 

air-dry montmorillonite gives a nearly integral series 

of reflections related to 12.6 A. After the montmorillonite is heated to 400°C, its reflections enhance those of 

illi,te at 3.3 and 10 A; ~a broad and sometimes diffuse refleetion appears in the region between 4.8 and 5.1 A, 

and a diffuse reflection appears near 3.2 A. After the 

mineral is heated to 525° or 550°C, the intensity of the 

reflection near 5 A is usually reduced, and the intensity 

of the 3.2-A reflection, relative to the reflection at 3.3 

A, is usually enhanced. 

Vermiculite was identified by a procedure recommended by Walker (1958; 1961, p. 314-317): combined 

treatment with glycerol and either magnesium chloride 

or sodiu1n hexametaphosphate. According to Walker, 

the montmorillonite lattice will expand to 18 A after 

such a treatment, whereas the vermiculite lattice will not 

expand beyond 15 A. Otherwise, the X-ray diffraction 

pattern of vermiculite 1and the responses of vermiculite 

to treatment with ethylene glycol and heat are similar 

to those of montmorillonite. Vermiculite was positively identified in only one of the eight cores-the 

Pixley core from the Tulare-Wasco area. 

MIXED-LAYER MONTMORILLONITE-ILLITE 

Another expanding-lattice mineral found in a fe,v of 

the sediments in the Los Banos-l{ettleman City area 

is tentatively identified as mixed-layer montmorillonite2 Angstrom unit=lo-scm. 

illite. X-ray diffraction patterns of a sample of this 

mineral are shown by the shaded reflections in the lower 

row of figure 39. This sample was saturated with sodium by treatment with dithionite and sodium citrate 

( Mehra and Jackson, 1960). The lower row of patterns 

also contains reflections ( unshaded) from illite, type-A 

chlorite, and quartz. 

Mixed-layer montmorillonite-illite, when treated with 

glycerol, gives a diffuse basal reflection at 18 A without 

giving any detectable higher order basal reflections. 

"'nen heated to 400° C, the mineral gives an integral 

series of sharp basal reflections related to 9.9 or 10.0 A. 

The intensity of the 10-A reflection from the heated 

mineral is several times greater than one would expect 

from the intensity of the reflection from the 001 plane 

of the mineral when it is expanded to 18 A. The diffuse 

band of reflections in the 10- to 14-A region is typical of 

the material when it is air dry and saturated with sodium. When the air-dry mineral is saturated with 

calcium and magnesium, the reflections are somewhat 

sharper and closer to 14 or 15 A. 

Although this mineral expands to 18 A when treated 

with glycerol, the broadness of the 18-A reflection and 

the sharp X-ray diffraction pattern from the heated 

specimen indicate that the mineral is very different from 

the type of montmorillonite illustrated in the upper row 

of figure 39. In contrast to the montmorillonite, it exhibits the greatest degree of structural order in the collapsed rather than in the expanded state. A mineral 

with similar X-ray diffraction characteristics has been 

found in the Pierre Shale and identified as a mixedlayer montmorillonite-illite (L. G. Schultz, 1961, oral 

commun.). 

ILLITE 

Illite is identified on the basis of the following characteristic series of reflections. 

Reflection Air-dry Glycerol or ethy- lene-glycol treated 

Heated to 400° C 

(001)---- 10. o-10. 2 A 9. 8-10. 0 A Masked by (001) re- flection from collapsed montmorillonite. 

(002) _____ 4. 98A 4. 93-4. 98A 4.98 A. 

(003) _____ 3. 33A 3. 35A 3.33 A. 

The slight shifts in the basal spacings of illite when 

treated with glycerol or ethylene glycol seem to indicate the presence of small amounts of expanding material. The intensities of the ( 001) and ( 003) reflections 

are always several times the intensity of the (002) 

reflection. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C69 

LOW·GRADE ILLITE-MONTMORILLONITE MIXTURE, 

Many samples contained small amounts of a material 

that is interpreted as a poorly crystalline mixture, not 

necessarily interlayered, of illite and montmorillonite. 

It gives a diffuse band of reflections between 9.0 and 

10.0 A when treated with glycerol, or between 8.5 and 

10 A when treated with ethylene glycol. When heated 

to 400° C, it gives a diffuse band of reflections between 

3.1 and 3.3 A and another between 4.8 and 5.0 A. 

CHLORITE 

At least two types of chlorite, distinguished from one 

another on the basis of their crystallinity as inferred 

from their X-ray diffraction patterns, were found in 

these sediments. These two are designated arbitrarily 

"type A" and "type B." Type A (fig. 40, sample A.) 

gives an integral series of sharp basal reflections related 

to 14 A that is not changed by heating the mineral to 

400° C. Type-B chlorite gives an integral series of 

reflections related to 14 A of which the (003) reflection 

at 4.7 A, poorly developed in air-dry specimens, is enhanced by heating to 400° C (fig. 40, sample B). This 

is presumably also true of the (001) reflection, which 

is masked by the ( 001) reflection of montmorillonite 

in X-ray patterns of air-dry samples. Heating both 

types of chlorite to 525° or 550° C strengthens the (001) 

reflection and destroys the higher order reflections. 

Heating to 650° C (patterns not shown in fig. 40) decreases the intensity of the ( 001) reflection by about 

half. 

In figure 40, the apparent decrease in the intensity 

of the reflections from chlorites A. and B after heating 

to 400° C was not a result of the heat treatment, but 

came about during an intermediate treatment with 

ethylene glycol. Although no decrease in the intensity 

of the reflections was noted between the glycol and heat 

treatments of these two samples, heating to 400° C did 

seem to reduce slightly the intensity of reflections from 

some chlorites. 

The type-B chlorite in the Santa Clara Valley is different from the type-B chlorite found in the San Joaquin Valley. Its X-ray diffraction patterns are different from the ones given in figure 40B in that the oddorder reflections are more intense, relative to the even 

orders, and the reflections at 4.7 and 2.8 A are always 

clearly visible in patten1s from air-dry specimens. The 

difference does not seem to be in the crystallinity of the 

chlorite in the Santa Clara Valley : the reflections are as 

diffuse as those of the type-B chlorite shown in figure 40, 

and the odd-order reflections are enhanced by heating 

the mineral to 400° C. The difference may be one of 

composition. As the odd-order reflections from magnesium-rich chlorites are more intense than the same reflections from iron-rich chlorites (Brindley and Gillery, 

1956), perhaps the chlorite in the Santa Clara Valley 

contains more magnesium and less iron than the chlorites 

in the San Joaquin Valley. 

KAOLINITE-TYPE MINERAL 

A kaolinite-type mineral was recognized by its two 

basal reflections near 7.2 and 3.'6 A (fig. 40, sample C). 

In air-dry samples, these reflections are broad, and their 

peaks are often diffuse-these facts suggest that the mineral is less well crystallized than the type-A and type-B 

chlorites. After treatment with glycerol or ethylene 

glycol, the peaks of the reflections may be shifted 0.1°-

0.40 28, or the reflections may become asymmetrical-the 

7-A reflection toward lower 20 angles (larger d spacings) and the 3.6-A reflection toward higher 28 angles. 

In some samples the organic liquids have no apparent 

effect, whereas in other samples the 3.6-A reflection becomes so diffuse after glycerol or ethylene-glycol treatment that it is barely discernible. After the mineral is 

heated to 400° C, these reflections are found nearer their 

air-dry positions, sometimes retaining part of the asymmetry developed during glycerol or ethylene-glycol 

treatment. After the mineral is heated to 525 ° or 550° 

C, these reflections are no longer visible. 

Although it has the appropriate 7-A struoture, the 

mineral cannot be identified specifically as kaolinite. 

The mineral sample whose diffraction pattern is shown 

in figure 400 was also examined in the Sedimentary 

Petrology Laboratory of the Geological Survey: P. D. 

Blackmon ( 1961, written commun.) reported that the 

mineral did not behave as kaolinite when subjected to 

the intersalation procedure prescribed by Andrew and 

others ( 1960) -a reliable means of distinguishing between kaolinite and structurally similar minerals such as 

chamosite and antigorite. Neither were any hexagonal 

terminations seen in the sample under the electron 

microscope. 

Because the identification of the kaolinite-type mineral or minerals was not pertinent to the aims of this 

study, other samples were not examined thoroughly. 

Where a mineral occurred whose X-ray diffraction pattern corresponded to figure 400, it was reported as "kaolinite-type mineral" with the understanding that it. 

could be either kaolini1te, antigorite, chamosite, or another structurally similar mineral. 

The kaolinite-type mineral and type-B chlorite commonly occur together in these sediments. The characteristic X-ray diffraction patterns of such a mixture are 

shown by sample D in figure 40. Double peaks appear 

at 7.1-7.2 A and at 3.5-3.6 A, and the odd-order reflections are less intense than those from pure type-B chlorite. Heating the mixture overnight in 6 N HCl destroys 
C70 

AIR-DRY 

14-15 

7.1 

3.55 10 

14-15 

7.1 

3.3 l 

3.51 

14-15 

7.2 

3.56 

14-15 

v 

MECHANICS OF AQUIFER SYSTEMS 

10 

7.1 

A 

10 

7.1 v 3.3 

B 

7.3 

c 

D 

3.3 

3.3 

3.3 

3.2 

4.9 

10 

10 

w 

10 

~ 

10 

FIGURE 40.-X-ray diffraction patterns of oriented aggregates of chlorite and kaolinite-type minerals. CuKcx radiation: scanning 

speed 2° per minute. Reflections from chlorite and kaolinite-type mtnerals shaded ; loeatLons given in Angstrom. units. 

Ordinate is linear intensity. A, Chlbrite, well crystallized, from depth of 1,134 feet, Mendota core hole. B, Chlorite, 

moderately well crystallized, from depth of 412 feet, Oro Loma core hole. 0, Kaolinite-type mineral, from depth of 1,512 feet, 

Cantua Creek core hole. D, 1\'lixture of chlorite (as in B) and kaolinite-type mineral from sediment suspended in Cantua Creek. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C71 

the chlorite reflections and leaves reflections at 7.2 and 

3.6 A. 

MINOR CHLORITIC MINERALS 

Some of the sediments in the Santa c·lara Valley contain a material that gives a small but broad reflection 

near 12 A when heated to 550° C. No other evidence of 

this mineral was seen in the X-ray diffraction pattern, 

and no evidence of it at all was seen at lower temperatures. It has been reported by Langston and others 

(1958, p. 225-227) from sediments in the vicinity of San 

Francisco Bay, and called by them "Chlorite, 12.3 A." 

This material may be a poorly crystallized interlayer 

mixture of chlorite and some expanding mineral such as 

montmorillonite. For lack of better information and 

understanding, the material is referred to in this report 

as the "the 12-A mineral." 

A regular mixed-layer chlorite-illite was identified on 

the basis of the integral series of basal reflections, 24 A, 

12 A, and 8 A. Higher order reflections may be present, 

but they are masked by reflections from other minerals, 

notably feldspar. The mineral was noted in only two 

samples, both of which came from a depth of 2,093 feet 

in the Huron core in the Los Banos-Kettleman City area. 

It is a minor constituent of these samples and is insignificant as a constituent of the sediments of the area. Its 

occurrence is reported here only as a matter of interest. 

RELATIVE PROPORTIONS OF :MINERAL SPECIES 

Most estimates of the proportions of clay minerals in 

a sediment are, at best, qualitative and arbitrary. The 

problems involved in estimating the relative amounts of 

clay minerals in complex mixtures such as one finds in 

sediments have been discussed by von Engelhardt 

(1959), Glenn and Handy (1962), Harward and Theisen (1962), Hathaway and Carroll (1954, p. 266-269), 

Jarvis and others (1957), Johns and others (1954), Norrish and Taylor (1962), Oinuma and Kobayashi (1961), 

Schultz (1960, 1964), and Weaver (1958, p. 270-271), 

but no standard method of estimation has been adopted. 

Clay mineralogists generally adapt arbitrary systems 

to the particular clay-mineral assemblages with which 

they are working. The system used in this study is also 

arbitrary. 

Proportions of montmorillonite, illite, mixed-layer 

montmorillonite-illite, and vermiculite were estimated 

by comparing the intensity of the reflection at 10 A before heat treatment to its intensity after heating the 

sample to 400° C. Illite and the expanding minerals 

were assumed to reflect X-rays with equal intensity at 

10 A. The amount of low-grade illite-montmorillonite 

mixture was estimated from the intensity of the band of 

reflections between 9.0 and 10.0 A in glycerol-treated 

232-511 0--616---4 

samples or between 8.5 and 10.0 A in ethylene glycoltreated samples. 

Proportions of chlorite and kaolinite-type minerals 

were estimated by a method based on work by Schultz 

(1960). Type-A chlorite, because of its high degree of 

crystallinity, was assumed to reflect X-rays at 7 A with 

twice the intensity that illite reflects X-rays at 10 A. 

The intensity of the 7-A reflection, therefore, was multiplied by 0.5 and compared with the 10-A reflection. The 

intensity of the 7-A reflection of type-B chlorite, less 

well crystallized than type A, was multiplied by 0.75 and 

compared with the illite reflection The kaolinite-type 

mineral, less well crystallized than the chlorites, was assumed to reflect X-rays at 7 A with the same intensity 

that illite reflects X-rays at 10 A. Where chlorite and 

the kaolinite-type mineral occurred in approximately 

equivalent amounts (as in sample D, fig. 40), the in tensity of the 7-A reflection was compared directly with 

the reflection at 10 A. 

Because the 12-A reflection is weak and because I have 

no basis for estimating its abundance, the 12-A mineral 

is reported as a trace where it is present. 

Estimated proportions of the clay minerals are expressed in parts per ten and given in tables 11 through 15 

and in table 18. Where a small amount of mixed-layer 

montmorillonite-illite or vermiculite is present with an 

overwhelming abundance of montmorillonite, it is noted 

in the tables as a trace and included in the figure for 

montmorillonite. The reverse is reported for samples 

in which mixed-layer montmorillonite-illite is much 

more abundant than. montmorillonite. Chlorite and 

the kaolinite-type mineral are reported in tables 11-13 

as "A," "B," "C," or "D," according to the X-ray diffraction patterns illustrated in figure 40 that approximate the patterns for the sample most closely. Chlorite 

and the kaolinite-type mineral probably never occur to 

the complete exclusion of one another, but samples that 

contain considerably more chlorite than kaolinite-type 

minerals are reported as pure chlorite with no kaolinitetype mineral, and vice versa. Where the proportions 

of the two minerals approach equality, the mixture is 

reported as "D." 

EXCHANGEABLE-CATION AND SOLUBLE-ANION 

ANALYSES 

Exchangeable cations were determined by H. C. Starkey and T. Manzanares, of the Sedimentary Petrology 

Laboratory, by the following procedure. One-gram 

samples of sediment finer than 2 mm were leached with 

1 N neutral NH4Cl. Sodium and potassium in the 

leachates were determined by flame photometry, calcium and magnesium by versene titration. Exchangeable hydrogen was measured by Brown's ( 1943) method, 
C72 MECHANICS OF AQUIFER SYSTEMS 

in samples that registered pH values of less than 7.0. 

The samples were then washed with alcohol, and the 

cation-exchange capacities were determined by ammonia 

distillation. The figures for cations in tables 11 

through 15 are the averages of duplicate analyses. 

Soluble anions were extracted by leaching 10 grams 

of dry sediment with 500 ml of hot water (temperature 

near boiling). Anions in the leachate were determined 

by Claude Huffman, A. J. Bartell, H. H. Lipp, and I. C. 

Frost, of the Sedimentary Petrology Laboratory. 

Chloride, bicarbonate, and carbonate were determined 

volumetrically; sulfate was determined gravimetrically. 

Where the sum of the anions in the leachate was less 

than 50 ppm (about 3 milliequivalents per 100 g of sediment), the individual anions were not determined but 

the total anions were estimated from the specific conductance of the leachate. The total dissolved salts in 

the leachate was also estimated from the specific conductance. 

The cations given in tables 11 through 15 are mostly 

exchangeable; that is, they represent approximately the 

ions adsorbed to the basal surfaces of the clay minerals. 

Exact quantitative evaluation of the amounts of each 

exchangeable cation species and the relations between 

species is impossible, however, because the sediments 

also contain calcite, gypsum, and perhaps other soluble 

salts. As a first approximation of the true sum of exchangeable cations, the measured sum has been adjusted 

for soluble salts by subtracting the total equivalents of 

the anions determined in the hot-water leach. This is 

only an adjustment in the right direction. It is not a 

correction, mainly because of the differences in the solubilities of calcite and gypsum in hot water and 1N 

NH4Cl. 

MEASUREMENT OF pH 

Several types of pH measurements were made, two 

of them in the Sedimentary Petrology Laboratory. 

The pH of a mixture, that had been allowed at least 

half an hour to reach equilibrium, of 1 gram of dry sediment and 10 ml of distilled water was determined in 

samples from the Tulare-Wasco and Santa Clara Valley 

cores. Also determined was the pH of the hot water 

leachates in which the soluble anions were identified. 

These pH values are listed in tables 11 through 15. 

In addition to the laboratory determinations, a few 

measurements were made. on selected fine sediments 

while coring operations were in progress at the Mendota and Cantua Creek holes in the Los Banos-Kettleman City area. Because the sediments were too hard 

for direct insertion of the pH electrodes, the clay had to 

be disaggregated and dispersed in water before measurements could be made. As soon as it was extracted 

from the core barrel, a sample of clay was mixed with 

distilled water (that had been allowed to come to equilibrium with the atmosphere) in proportions of approximately 1 part of clay to 3 parts water by volume. 

Measurements of pH were made as follows: 

pH of clay-water suspension 

Depth below land 

surface (feet) 

pH of water I----~----I Temperature before clay of suspension was added Within a few 1 hour after (° C.) 

Mendota core 1 

435 ____________ ---------- 600 ____________ ---------- 980 ____________ ----------

Cantua Creek core 

821___________ a 8 

942___________ 5. 7 

minutes of mixing mixing 

7. 9 

8.4 

8. 7 

8. 9 

8. 6 ----------

---------- 12 

14 

1156___________ 5. 6 9. 6 10 ---------- 1327___________ 5. 7 9. 1 9. 2 16 

1475___________ 5. 7 8. 7 9. 3 15 

1836___________ a 8 9. 9 9. 6 14 

1952___________ a 9 8. 3 8. 7 17 

1 Measurements in Mendota core made by Nikola Prokopovich, U.S. 

Bur. Reclamation. 

Although this is a common procedure for measuring 

the pH of clays (see, for example, Bassett, 1950), precisely wha;t is measured by placing 'an electrode into a 

mixture of clay minerals, nonclay minerals, distilled 

water, and interstitial water containing dissolved salts 

is obscure. The numerical values given in the table 

certainly are not to be interpreted rigorously because 

they ·are subject to many influences, intrinsic and extraneous. Vigorous stirring of the mixture, for instance, caused the pH m~ter to register increases of as 

much as 0.7 pH unit. 

TABLES OF DATA ON CLAY MINERALS AND 

CHEMICAL ANALYSES 

Tables 11 through 15 contain the results of the claymineral, exchangeable-cation, and soluble-anion analyses of samples from the Los Banos-Kettleman City 

area, Tulare-Wasco area, and Santa Clara Valley. Unless otherwise indicated, the clay-mineral proportions 

reported are those in the 0.2p.-2.0p. fraction. Because 

the estimated day-mineral proportions were rounded 

off to the nearest part in ten, the total of the parts do 

not add up to 10 in all samples. The ca·tions, cationexchange capacity, soluble anions, and pH of 10: 1 

water-sediment mixture were determined using the unfractionated sample ground to pass a 2-mm sieve. 

Tables 16 and 17 contain data not published elsewhere on the chemical quality of water being pumped 

from wells near ·the Sunnyvale and San Jose core holes 

in the Santa Clara Valley. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA 

TABLE 11.-Clay minerals and associated ions in fine-grained sediments from cores in the Los Banos-Kettleman City area 

[Cations and cation-exchange capacity determined by H. C. Starkey; anions and pH of hot-water leachate by H. H. Lipp, I. C. Frost, and Claude Huffman] 

Depth below 

land surface 

(feet) 

85----------------- 2 154_________________ Tr. 

231----------------- Tr. a75_________________ 8 412_________________ 8 

423----------------- 8 472_________________ 7 575_________________ 8 625_________________ 7 

675_________________ 7 719_________________ 7 724_________________ 7 

823_________________ 9 

Mean: 

85-231_ ------- a75-823 ______ _ 1 

7~ 

Clay minerals 

(estimated parts per ten) 

1 

5 

5 

0 

0 

0 Tr. 0 

0 

0 Tr. 

Tr. 0 

4 

0 

5 

a 

2 

1 

Tr. 

Tr. 1 

Tr. 1 

1 

Tr. 1 

Tr. 

0 2 A 0 2 A o a A Tr. Tr. 

Tr. 1 B 

Tr. 2 D 

Tr. 2 D Tr. 2 D 

Tr. 2 B Tr. 2 B Tr. 2 B 0 2 D Tr. Tr. 

0 2 A Tr. 1~ BD 

75__________________ 7 0 Tr. Tr. 2 D 

230------------------ 6 0 1 Tr. a D a15 3________________ 6 Tr. 1 Tr. a B 

a99__________________ 6 0 1 1 2 D 55L________________ 6 0 1 Tr. 2 B 554 3________________ 6 0 2 Tr. 2 B 63L________________ 7 0 2 0 1 D 6423________________ 8 0 Tr. Tr. 1 D 69a__________________ 6 0 2 Tr. 2 D 699 3________________ 7 0 1 Tr. 2 B 

746------------------ 6 Tr. 2 Tr. 2 D 746 3________________ 7 0 Tr. Tr. 2 D 780-_________________ 7 0 1 Tr. 2 B saL_________________ 6 o a Tr. 1 B 

833__________________ 6 0 2 Tr. 2 D 932__________________ 7 0 2 Tr. 1 D 98L________________ 6 0 1 1 2 D 9843 ________________ 7 0 1 Tr. 2 A 

I,oao__________________ 4 a 1 o 2 A 

1,076 3________________ 7 0 1 0 2 B l,la4__________________ 7 Tr. 2 0 1 A 1,280__________________ 7 0 2 0 1 B 1,a51 3________________ 8 0 Tr. 0 1 B 

G!l 

u 

Cations 

(meq/100 g) 

Oro Lorna core 

21. 1 4. 7 0. 0 0. 0 

Mendota core 

25. 1 11. 6 4. 7 0. 0 

22.5 

35.2 

Anions 

(meq/100 g) 

0 

u 0 1:!: u 

21.9 -------- 2.0 1.0 0.0 o.a a. a 

19.6 35 1.4 4. 3 0. 0 0. 5 6. 2 

51 

99 

C73 

7.2 

7.6 

1,a953________________ 8 Tr. Tr. 0 2 B ________________________________________ -------- ______ -------- ______ ------ ------ -------- -------- 1,400__________________ 8 0 Tr. 1 Tr. _______________________________________________________________________________________________ _ 

1443 7 Tr. 1 1 1 D 25.7 4.a 9.0 .0 a7.0 35.6 55 __________________________ 2.0 31 7.2 ;450-3~~=============: __ 8 ____ o ___ T_r_. ____ o __ I__ B_________________________________________________________________________________________ --------

Mean __________ _ Tr. Tr. 1~ BD 

Cantua Creek core 

---------------;-------------------------------~----~--~---~--~----~----~----------------------------- -------------

299 ________________ _ 

418 ________________ _ 540 ________________ _ 

572 _______ ---------- 652 ________________ _ 

746 ________________ _ 828 ________________ _ 902 ________________ _ 

973 ________________ _ 

1, 043 __ --------------- 1,154 __ - -------------- 1,238 ________________ _ 

1,327 _____________ ---

1, 414_-- -------------- 1,512 ________________ _ 

I, 632 __ --------------- 1, 717 ________________ _ 

1, 792 ________________ _ 

1,87L _______________ _ 1,952 ________________ _ 

Mean __________ _ 

6 

8 

7 

7 

8 

8 

7 

7 

8 

6 

6 

6 

9 

8 

7 

7 

7 

7 

5 

6 

See footnotes at end of table. 

0 

0 

0 

0 

0 

0 Tr. 0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

1 

1 

1 

1 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

2 

2 

1 

Tr. 

1 

Tr. 

1 

2 

2 

2 

3 

0 3 D Tr. 1 D 

Tr. 2 D Tr. 1 B 

0 1 B Tr. 2 C Tr. 2 D Tr. 2 D 0 1 D Tr. 2 D Tr. 2 D Tr. 2 D Tr. Tr. 

Tr. 1 D Tr. 2 C 0 2 D Tr. 1 D 0 1 D 1 2 B Tr. Tr. 

Tr. 131 D 

22. 8 23. 3 2. 0 .0 47.1 45.7 70 ------ -------- ------ ------ 1. 0 16 7.2 

29. 6 18. 6 2. 0 .0 48.0 37.8 55 ------ -------- ------ ------ 2.2 35 7.4 

35.8 1. 2 8. 0 .0 42.2 40.4 70 ------ -------- ------ ------ 2.8 44 7. 7 

12.2 1. 3 5. 7 .0 16.7 15.0 30 ------ -------- ------ ------ 2.5 41 7.8 
C74 MECHANICS OF AQUIFER SYSTEMS 

TABLE 11.-Clay minerals and associated ions in fine-grained sediments from cores in the Los Banos-Kettleman City area-Continued 

Depth below 

land surface 

(feet) 

165.---------------- 312 3 _______________ _ 

313.----------------

.70.---------------- 555 3 _______________ _ 

735.---------------- 735 3 _______________ _ 

905.---------------- 905 3 _______________ _ 

1, 030.----------------

1,094 ·---------------- 1,179 •..•.... ---------- 1,2513 _______________ _ 1,345 a _______________ _ 

1,387------------------ 1,524 a _______________ _ 1,6013 _______________ _ 

1,651_ ________ --------- 1,750 a _______________ _ 

1,801 ••.•... ----------- 1,899 •..• -------------- 1,956 a _______________ _ 

2,021 3----------------

2,093 ..•... ------------

2,093 ·----------------

Mean __________ _ 

8 

8 

8 

6 

8 

7 

7 

8 

8 

8 

8 

7 

8 

9 

8 

9 

8 

7 

9 

7 

8 

8 

8 

5 

6 

Clay minerals 

(estimated parts per ten) 

0 

0 

0 

0 

0 Tr. 

Tr. 0 

0 

0 

0 

0 

0 

0 

0 

0 Tr. 0 

0 

0 

0 Tr. 

Tr. 

Tr. 

Tr. 

0 

1 

Tr. 

Tr. 

2 

Tr. 

1 

1 

Tr. 

Tr. 

1 

Tr. 1 

Tr. 

Tr. 

Tr. 

Tr. 1 

1 Tr. 1 

1 

1 

1 

3 

2 

Tr. 1 B 

Tr. 1 B 

Tr. 1 B 

Tr. 2 B 

Tr. 1 B 

Tr. 2 B 

Tr. 2 B 0 1 B 

0 1 B 

9 1 B 

0 1 B 

Tr. 2 D 

Tr. 1 B 

Tr. 1 B 

Tr. 2 B 

Tr. Tr. 

Tr. 1 B 

1 1 D 

Tr. 1 D 

1 1 D 

Tr. 1 D 

Tr. 1 D 

Tr. 1 B 0 2 D 0 2 D 

Tr. 1~ BD 

' Letters refer to mineral types shown in figure 40. 2 Sum of cations minus sum of anions. 

u "' 

Cations 

(meq/100g) 

Huron core 

25. 3 21. 4 2. 0 0. 0 

43. 2 21. 2 4. 2 .0 

46.2 41.8 

65.2 39.8 

0 

rJ:J 

Anions 

(meq/100 g) 

0 

u 0 ~ u 

55 ------ -------- ------ ------ 2.5 

50 0.4 3.0 0.0 <0.2 3.4 

41 7. 7 

53 7.9 

a X-ray analysis made in Sedimentary Petrology Laboratory of the U.S. Geological 

Survey by J. C. Hathaway, H. C. Starkey, and G. W. Chloe; <2p fraction. 

TABLE 12.-Clay minerals and associated ions in surface and near-surface alluvial sediments, Los Banos-Kettleman City area 

[Cations and cation-exchange capacity determined by H. C. Starkey; anions and pH of hot-water leachate determined by H. H. Lipp, I. C. Frost, and Claude Hu:ffman] 

Sample 

No., 

fig. 14 

Stream 

or fan 

Material 

sampled 

Clay minerals 

(estimated parts per ten) 

Cations 

(meq/100 g) 

z "' 0 

rJ:J 

Anions 

(meq/100g) 

0 

u 0 ~ ~ u '-' 

s 

::s 

rJ:J 

Surface and near-surface sediments 

L _____ Little S'Uspended .• 0 

0 

0 

Tr. 

Panoche. 2 ______ ...•• do _________ Bed ________ _ 3 ______ Moreno Fan ________ _ 

Gulch.a ..... do.a ____________ do ______ _ 4 .. ___ Unnamed a f _______ do ______ _ ....• do.a f ______ ••••• do ______ _ 5 ______ Panoche. _____ Suspended .• 6 .•........• do _________ Bank ... __ _ 7 ______ Arroyo Fan ________ _ 

Ciervo.a _____ do.a ____________ do ______ _ 8 ______ Cantua _______ Suspended __ 9. _____ ..... do _________ Flood plain. lQ ______ Salt; __________ Suspended __ 11 ______ Martinez a _____ Fan ________ _ 

12 ...... p:<>s~aios~~=== -B"e<i~ _-~-:==: 

55 

0 

24 

0 

0 

0 

33 

0 

0 

0 

0 

71 

0 

' Letters refer to mineral types shown in figure 40. 2 Sum of cations minus sum of anions. a Samples collected by W. B. Bull. 

2 

7 

4 

8 

9 

7 

7 

8 

8 

7 

7 

7 

7 

8 

6 

3 

2 

Tr. 

Tr. 

Tr. 0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

6 

4 

1 

3 Tr. 

Tr. 1 

1 Tr. 

0 

0 Tr. 

Tr. 

Tr. 0 Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 0 Tr. 

Tr. 

1 A 

1 A 

2D 

3B 

1 D 

Tr. 

2D 

2 c 

lD 

1 

2D 

2D 

2D 

1 D 

1D 

2D 

15. 6 2. 9 0. 0 0. 0 9. 9 6. 8 10 0.5 4.0 0.0 4.1 8.6 140 8.2 

7. 5 --------------------------------------------------------- ------ ------ ------ ------ 17.7 6.6 43 .0 .0 21.6 9.3 15 ------ ------ ------ ------ 2. 7 

---- ------ ------ ------ ------ ------ "iii~s- ··sx --~5- --~o- -23~9- -iii~9- ---if========----____________ 2. o aa 7.3 

f First unnamed stream south of Capita Canyon. . ; Sample represents mixture of Salt and Cantua Creeks; Salt Creek contammated 

at time of sampling. 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C75 

TABLE 13.-Clay minerals and associated ions in fine-grained sediments from cores in Tulare-Wasco area 

[Cations, cation-exchange capacity and pH of 10:1 water-sediment mixtures determined by H. C. Starkey; anions and pH of hot-water leachate determined by Claude Huff- man and A. J. Bartell] 

Clay minerals( estimated parts per ten) ...!., 

Cations (meq/100 g) 

1----~---~----~-------l----~----~~----,-----------

Anions (meq/100 g) ~ .. ....... pH 

1----------------------1 'C ~ 8 1------~---- ~~!5: Depth below land '0~~ surface (feet) 

70 _____________ 0.2-2.0 

268_ ------------ .2-2.0 288_ ------------ .2-2.0 45L _ ----------- .2-2.0 601_ ____________ .2-2.0 

724_- ----------- .2-2.0 

Mean _______ .2-2.0 

148_- ----------- 0. 2-2.0 

232_- -----------

290 _____________ _ 

371_ - -----------

444_- -------

517_-

583_-

649 ___ ---------

764_- -----------

844_-

917-- -------- -

1,036 ----- - -

1,156_-------------

1,240 _________ _ 

1 ,364_- - - --

.1- . 2 

. 2-2.0 

.1- . 2 

. 2-2.0 

. 1- . 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

. 1- . 2 . 2-2.0 

. 1- . 2 

. 2-2.0 

. 1-. 2 

<.1 

<2.1 

. 2-2.0 

. 1- . 2 

. 2-2.0 

.1- . 2 

<5.1 

. 2-2.0 

. 1- .2 . 2-2.0 

. 1-. 2 1,447 ____ - -- <10.1 

. 2-2.0 

. 1-. 2 1,527______________ <10 .I 

1,689 _____________ _ 

1,827 _____________ _ 

1,912 _____________ _ 

Mean: 

0. 2-2.0 

. 1- .2 

.2-2.0 

. 1- . 2 <10.1 

. 2-2.0 

.1- ·. 2 

<10.1 

. 2-2.0 

. 1- .2 

148-649____ . 2-2.0 

764-1, 82L . 2-2.0 

9 Tr. 6 2 

9 Tr. 7 1 

5 2 

6 2 

7 2 

7 2 

5 3 

7 2 

6 3 

7 2 

6 3 

6 2 

5 4 

6 2 

6 3 

6 2 

7 2 

8 1 

6 3 

6 3 

7 3 

8 2 

9 Tr. 9 Tr. 8 Tr. 9 Tr . 10 0 8 1 

7 1 

8 1 

8 Tr. 8 Tr. 8 Tr. 8 1 

9 Tr. 8 Tr. 8 Tr . 7 1 

9 Tr . 9 Tr. 6 2 

8 Tr. 9 Tr . 9 1 

9 Tr. 9 Tr. 9 Tr. 9 Tr. 7 2 

8 Tr . 8 Tr . 

0 lC 0 1C 0 Tr. 0 2C 0 3C 0 2C 

0 172C 

0 1 c 0 1 c Tr. 1 C 0 1 c 0 1 c 0 2 c 0 1 c 0 2 c 0 1 c 0 2 c 0 1 c 0 2 c Tr. 1 C 

0 1 c 0 Tr . 0 1 c 0 Tr. 0 Tr . 0 Tr . Tr. Tr . 0 1 D Tr. 1 C 0 Tr. 0 1 D Tr. 2 D Tr. 1 C Tr. 1 D 

Tr. 1 C 0 1 D 0 1 c 0 Tr . 0 1 D Tr. 1 C 0 2 D 0 1 c 0 Tr . 0 2 D Tr. 1 C Tr. Tr. Tr. Tr. 0 Tr . 0 Tr. 0 Tr . Tr. Tr. 0 1 c Tr. 1 C Tr. 2 C 

I 

6 

8 3 Tr. c ~2 Tr. DC 

13.3 

20.4 

36.3 

21.3 

20.0 

22.4 

4.5 

2.5 

1.3 

3.1 

1.1 

2.5 

Pixley core 

0.0 

1.2 

.0 

1.8 

1.5 

1.2 

0.0 

.0 

.0 

.0 

.0 

.0 

Richgrove core 

22. 9 9. 4 1. 1 0. 0 

20.0 3.8 .6 .0 

27.6 3.1 2.4 .0 

22.9 3.8 .0 .0 

14. 1 3. 4 . 0 . 0 

40.7 4.4 .0 .0 

26.3 4.9 .0 .0 

22.0 4.5 .0 .0 

36. 8 9. 4 4. 2 . 6 

32.1 4.0 3.9 .0 

28.3 6.3 5.7 .0 

24. 3 9. 0 6. 6 . 5 

12. 6 6. 3 3. 8 . 0 

9. 4 13. 3 6. 6 . 0 7. 5 

16. 0 6. 0 5. 7 . 0 

17.5 12.6 7.4 .0 7.1 

11. 7 13. 2 7. 5 . 0 10. 9 

29. 0 6. 7 10. 7 . 0 

8. 0 17. 5 11. 1 . 0 13. 0 

10. 6 3. 6 2. 7 . 0 4. 0 

16.8 

23.4 

35.6 

24.9 

21.5 

25.1 

32.6 

23.7 

31.6 

26.1 

17. 1 

43.6 

30.5 

25.2 

44.8 

37.3 

35.6 

33.2 

20.1 

26.1 

24.8 

25.0 

23.0 

41.2 

35.1 

14.9 

14.5 

21.3 

32.8 

21.6 

18.8 

22.5 

30.3 

22.1 

31.6 

22.2 

14.8 

16.7 

29.0 

25.3 

0 

00 

40.7 1. 4 

29.1 

31.9 2. 6 

35.4 4.0 

21.1 

36.3 10.4 

24.5 

28.7 18.9 

31.4 19.7 

37.8 3. 3 

43.5 13. 7 

11.6 5. 2 

g G 

1.0 

.7 

2.0 

1.3 

1.1 

1.0 

0.8 

.7 

1. 5 

.6 

.4 

1.5 

.7 

1.3 

3. 7 0. 0 0. 5 5. 6 

2. 7 

2.1 .0 .0 4.7 

2. 7 . 0 . 0 6. 7 

2.6 

. 4 . 0 . 0 10.8 

2. 9 

. 6 . 0 . 0 19.5 

. 6 . 0 . 0 20.3 

1. 9 . 0 . 0 5. 2 

. 7 . 0 .0 14.4 

. 7 . 0 . 0 5. 9 

.~.8~ -c.s..c: 

3~~ o·-...... E-< 

16 

11 

32 

21 

18 

15 

13 

11 

24 

9 

6 

24 

12 

21 

74 

43 

62 

94 

41 

170 

47 

290 

300 

69 

230 

98 

7.3 

7.3 

7.5 

8.4 

7.8 

7.8 

7. 5 

7.6 

6. 7 

7. 3 

7. 0 

7. 2 

6. 7 

7. 1 

7. 7 

7. 3 

7. 7 

7.8 

6.8 

6. 5 

7. 5 

6. 2 

6. 2 

7. 4 

6. 7 

6. 9 

I ~ ______ ___:_ __ __:____ __ _:_ _ _:_ __ ___:__ __ ______:___ _ ___:_ _ ______:___ _ _:__:_________:___ __ __c_____ _ ___:__ _ ___:__ __ ___:___:______:__ ___ --------------

I Refers to clay-mineral determinations only; chemical determinations were made on unfractionated sediment. 2 Includes some vermiculite in samples from Pixley core. 

a Letters refer to type of X-ray-diffraction pattern shown in figure 40. • Sum of cations minus sum of anions. .1 Sediment flocculated during centrifuging. 

8.9 

8.7 

8.8 

8.7 

8.8 

8.9 

8.4 

8. 7 

8. 7 

8. 9 

8. 7 

9.1 

8.6 

8. 7 

1!. 4 

8. 7 

8. 5 

8. 5 

8. 6 

4.5 

8. 7 

4. 0 

4.0 

7. 5 

4.1 

5.3 
C76 MECHANICS OF AQUIFER SYSTEMS 

TABLE 14.-Clay minerals and associated ions in fine-grained sediments from cores in Santa Clara Valley 

Clay-minerals determined with assistance of J. B. Corliss; cations, cation-exchange capacity, and pH of 10:1 water-sediment mixture determined by H. C. Starkey and Toribio Manzanares, Jr.; anions and pH of hot-water leachate determined by A. J. Bartel] 

Depth below land surface (feet) 

80 __________________ _ 

142_ ------------------

222 __________________ _ 

313 __________________ _ 

437 __________________ _ 

526 __________________ _ 

6()6 __________________ _ 

656 __________________ _ 

746 __________________ _ 

813 __________________ _ 

901 ________ ----------

983 __________________ _ 

i 

~~ !·a "''-" 

.... ~= 0 

s:: tO 

Po<\1 

~.t= 

C) 

0. 2-2.0 

.1-. 2 . 2-2.0 

. 1- . 2 . 2-2.0 

. 1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

. 1-. 2 . 2-2.0 

. 1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

. 1-. 2 .2-2. 0 . 1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 

Mean__________ . 2-2.0 

40_-- ----------------

207-------------------

302_-- ----------------

41)2 __________________ _ 

542-------------------

727-------------------

833_-- ----------------

937 __________________ _ 

0. 2-2.0 

.1-. 2 .2-2. 0 .1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1- .2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 . 2-2.0 

.1-. 2 

Mean__________ . 2-2.0 

Clay minerals Cations (meq/100 g) 

(estimated parts per ten) 

13 

OQ) 

.§:a !:lo 

~-

5 

7 

7 

9 

8 

9 

7 

8 

7 

9 

8 

9 

8 

9 

9 

9 

8 

9 

7 

7 

6 

8 

9 

9 

772 

5 

7 

6 

7 

8 

9 

6 

8 

7 

8 

7 

8 

8 

8 

7 

8 

7 

Q) 

~ 

s 

2 

1 Tr. 

Tr. 

Tr. 

Tr. 

1 

Tr. 

Tr. 

Tr. 

1 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

1 Tr. 

Tr. 

Tr. 

2 

2 

1 

1 

1 Tr. 

1 Tr. 1 Tr. 1 Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

<D~~ 

~a.§ 

to~1: ~;::::: 0 

o:=S 

.:I 

0 

0 

0 Tr . Tr. 

Tr . 

0 

0 

0 Tr . 

0 Tr. 

0 Tr. 

Tr. 

Tr. 

Tr. 

Tr . 

0 Tr . 

0 

0 

0 

0 

Tr. 

0 

0 

0 

0 

0 

0 

0 

0 Tr. 

Tr. 

0 

0 

0 

0 Tr. 

Tr. 

Tr. 

Q)$ 

~~ :ae "' l:>ll d 

0 C) ::s z ~ 

Sunnyvale core 

3 

2 

2 

1 

2 

1 

1 

1 

2 

1 

1 Tr . 

2 

1 

1 Tr. 

2 

1 

2 

2 

3 

2 

1 Tr. 

2B 

43.9 9. 4 

16.6 8. 0 

29.4 12.8 

13.1 3. 5 

29.8 6. 8 

49.0 21.5 

38.3 23.4 

67.2 25.9 

46.0 18.8 

16.9 7. 1 

20.9 8. 5 

29.8 9. 4 

0.0 

. 0 

.0 

.0 

.0 

.0 

.0 

.0 

1.3 

1.1 

1.6 

3. 7 

0.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

. 0 

.0 

San Jose core 

3 24.2 2 

3 21.2 2 

1 11.9 1 

3 21.9 1 

2 20.5 1 

2 15.1 2 

2 43.3 1 

2 19.6 2 

2B 

8. 6 

6. 2 

5.1 

8.3 

7.6 

6.1 

9. 5 

8. 6 

0. 0 

.0 

.0 

. 0 

.0 

.0 

.0 

.0 

0. 0 

.0 

.0 

.0 

.0 

.0 

. 0 

,o 

"0 

<D .. 

·~::l ~= 'Om 

....:: 

51.2 

21.7 

40.6 

16.1 

34.3 

67.7 

57.3 

89.6 

61.5 

23.5 

28.2 

41.7 

29.4 

25.4 

16.2 

27.5 

26.7 

19.6 

50.5 

26.6 

bO 

8 

Q)~ 

~Q) 418 

..C::'-" 

Op. 

~~ 

~~ ,SP. 

~d 

<\10 

0 

10.4 

19.3 

33.8 

19.4 

15.6 

17.2 

17.3 

21.8 

33.6 

23.4 

24.0 

40.6 

28.0 

27.7 

16.4 

26.9 

20.1 

17.6 

21.9 

22.0 

Anions (meq/100 g) 

0 

0 C) 0 w. ~ C) u 

0.0 4.4 0.0 0.0 

.0 3.5 .0 .0 

.6 4.0 .0 .0 

0.7 2.7 0.0 0.0 

t Refers to clay-mineral determinations only; chemical determinations were made on unfractionated sediments. 

2 Sum of cations minus sum of anions. 

s 

::l 

w. 

2.1 

2. 9 

1.6 

. 5 

2.3 

2.8 

4.4 

3. 5 

4. 6 

1.6 

2.8 

1. 2 

3.4 

2. 0 

.8 

2. 7 

1.4 

1.6 

2.3 

1.6 

.... ~· ..c:: ..... o o., 

I'll a) 

"0 ..... Q) ... ~Q) 

"O~j ~~ 

;a~g 

-;..c::Q) 

~=~ 0• ... d 

~ 

34 

46 

25 

8 

36 

45 

62 

51 

66 

27 

46 

19 

49 

32 

13 

44 

23 

25 

37 

26 

pH 

... Q) Q)~ 

~., 

"'..c:: 

~0 ,., 

~Q) o ..... 

~ 

6.8 

6.6 

6. 8 

6.8 

7. 2 

7.3 

8.3 

7.6 

7. 5 

7. 0 

7. 5 

6. 7 

7. 3 

7.1 

6. 9 

7. 0 

7.1 

7.1 

7.3 

7.3 

.!.1::Q) 

~83 ~-... ~ "0-

~ms 

8.6 

7. 9 

8. 7 

8.5 

8.9 

9.1 

9. 2 

9.4 

9.1 

9.4 

9.3 

9. 2 

8. 5 

8.6 

8. 5 

8. 5 

9.1 

8.9 

9. 2 

9.1 
PETROLOGY, SEDIMENTS UNDERLYING AREAS OF LAND SUBSIDENCE, CENTRAL CALIFORNIA C77 

TABLE 15.-Clay minerals and associated ions in fine-grained surficial sediments from Santa Clara. Valley and southern San Francisco Bay 

[Clay minerals in samples 1-11 determined with assistance of J. B. Corliss, T. J. Conomos, and J. 0. Berkland. Samples 12-19 are grab samples, collected and analyzed by 

Conomos. Cations, cation-exchange capacity, and pH of 10:1 water-sediment mixtures determined by H. C. Starkey and Toribio Manzanares, Jr.; anions and pH of 

hot-water leachates determined by A. J. Bartelj 

Sample 

No. in 

fig. 34 

Sediment type 

and location 

Clay minerals (estimated 

parts per ten) 

Q:> 

Q:> 

~ A 0 "Ct'_ f ~ as,$ Q:> 

a:>"E f s ·§ 1:=§~ ~ Q:> 

0 ~.:·§ < 

::g ~ ~ 0 ~ 

Cations (meq/100 g) t' 

·z 

~ 

A 

~ 

<:) 

Q:> 

bl) 

.:: 

~~ -§8 

~~ >::0' 

oa:> 

s 

::l ~= ~._., 

r:JJ 0 0 r:JJ 

Anions (meq/100 g) 

0 

0 6 

pH 

----1--------1----------------------------------------------

Alluvial 

L_______ San Francisquito 

Creek fan. 2 _____________ do ____________ _ 

3________ Stevens Creek 

bank. 

4________ Los Gatos Creek 

terrace. 5 ________ Coyote Creek 

terrace. 6 _____________ do ____________ _ 7 ________ Agnew 2 __________ _ 

8 ________ Alameda Creek 

bottom. 

Bay bottom 

9 ________ Brewer Island 3 ___ 10 ________ San Francisco 

Bay. 1L _______ Mayfield Slough __ 12 ________ Coyote Slough ____ 13 ____ ---- San Francisco 

Bay. 14 ________ _____ do _____________ 

15 ____ ---- _____ do _____________ 16 ________ _____ do _____________ 17 ________ _____ do _____________ 18 ________ _____ do _____________ 19 ________ _____ do _____________ 

8 Tr. 2 c 

9 Tr_ 1 C 

7 1 2 D 

8 1 D 

7 2 B 

7 1 2 B 

8 Tr. 1 B 7 1 2 c 

6 2 2B 5 3 2B 

6 2 2B 6 2 2B 5 2 3B 

6 1 2B 7 1 2B 6 2 3B 6 2 2B 6 2 2B 6 2 2B 

0 27.6 10.2 0. 0 0. 0 ------ 37.8 

0 Tr. 

Tr. 

Tr. 

Tr. 0 Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

0 Tr. 

Tr. 

0 Tr. 

23.2 18.1 44.2 1.2 ------ 86.7 

16. 1 32. 8 55. 9 1. 2 8. 0 114. 0 

36.6 ------ -------- ------ ------ 1. 0 16 

32.9 8. 3 4. 5 0. 0 40. 7 53. 6 810 

36.2 49.7 .0 . 0 58. 2 107. 9 1, 500 

' Letters refer to type of X-ray diffraction pattern shown in figure 40. 2 Slight soil profile developed. 3 Reclaimed bay-bottom sediments. 

TABLE 16.-Partial chemical analyses of water from selected wells within about 3 miles of Sunnyvale core hole 

[Analyses by W. C. Pollard, B. H. Geib, Edelle Hansen, and Ignacio Sokula] 

Dis- Perforated Parts per million (upper number) and equivalents per million tance interval (feet) Total (lower number) for indicated cations and anions 

from Total - Day water disWell location (T/R-Sec) Sunny- depth sample col- solved 

vale (feet) lected solids core Top Bot- (ppm) Ca Mg Na K S04 HCOa CO a Cl 

hole tom (mile) 

------------ --------------------------

68/1~r-19 ___________ 1.3 550 ----- ----- 8/14/57 354 58 18 41 1.6 35 268 0. 0 26 

2. 9 1.5 1.8 0. 04 0. 7 4. 4 ----- 0. 7 

68/1VV-29 ___________ 2. 7 300 ----- ----- 8/17/54 288 42 18 31 1.0 34 220 .0 15 

2. 1 1.5 1. 3 0. 03 0. 7 3. 6 ----- 0. 4 

68/2VV-9 ____________ 3. 1 202 163 185 8/14/57 355 46 15 60 2. () 27 272 .0 39 

2. 3 1.2 2. 6 0. 05 0. 6 4. 4 ----- 1. 1 

68/2VV-14 ___________ .4 868 ----- ----- ___ do _____ 311 46 14 47 1.4 27 262 .0 2fl 

2. 3 1. 1 2. 0 0. 04 0. 6 4. 3 ----- 0. 6 

68/2VV-16 ___________ 2. 8 500 ----- ----- ___ do _____ 542 103 31 38 1.6 127 327 .0 45 

5. 1 2. 6 1.6 0. 04 2. 6 5. 4 ----- 1.3 68/2VV-21 ___________ 2. 7 264 ----- ----- 8jl8/54 539 83 30 48 1.5 150 249 .0 50 

4. 1 2. 5 2. 1 0. 04 3. 1 4. 1 ----- 1.4 

68/2VV-24_ ---------- .6 550 150 535 8/11/53 324 50 18 40 1.2 32 268 .0 20 

2. 5 1.5 1.7 0. 03 0. 7 4. 4 ----- 0. 6 

68/2VV-28_ ---------- 3. 1 320 190 316 8/15/57 361 75 23 22 1.3 22 315 .0 29 

3. 7 1.9 1.0 0. 03 0. 5 5. 2 ----- 0. 8 

68/2VV -34 _ _ ________ 3. 3 660 ----- ----- ___ do _____ 294 53 19 21 1.2 15 249 .0 20 

2. 6 1.6 0. 9 0.03 0. 3 4. 1 ----- 0. 6 

68/2VV -36 ___________ 2. 5 480 ----- ----- ___ do _____ 444 95 21 33 1.9 41 322 .0 50 

4. 7 1.7 1.4 0. 05 0. 8 5. 3 ----- 1.4 

7. 0 8.5 

7.4 8.3 

4.6 4.0 

Per- Si02 cent (ppm) Na 

----

30 2. 9 

------ ---

33 2 7 

------ ---

32 4 2 

------ ----

26 :3' - ----- -- --

:30 L 

------ ----

-Hl 2 4 

------ ---

:30 3{ 

------ - --

30 1 

------ ---

30 1t 8 

------ ---

28 1 8 

------ ----
C78 MECHANICS OF AQUIFER SYSTEMS 

TABLE 17.-Partial chemical analyses of water from wells within 200 yards of San Jose core hole 

[All wells in 12th Street Station of San Jose Water Works; samples collected and analyzed by Water Works: analyst, Primo Villarruz. Well nnmber!3 are those assigned by Water Works] 

Perforated Parts per million (upper nnmber) and equivalents per million (lower interval (feet) Total 

Well Total Day water disdepth sample solved 

(feet) Top Bottom collected solids Ca 

(ppm) 

--- ----

4 ______________ 800 605 780 1/31/62 336 52 

2. 6 5 ______________ 800 454 778 ___ do _____ 427 72 

3. 6 6 ______________ 794 276 772 2/15/62 387 63 

3. 1 7 ______________ 725 278 682 1/31/62 396 74 

3. 7 g ______________ 716 280 697 2/3/62 390 59 

3. 0 g ______________ 800 270 746 4/4/62 408 72 

3. 6 11. ____________ 870 306 842 1/22/62 355 47 

2. 4 

Tahle 18 contains the results of clay-mineral analyses 

of sediments from the Lakeview test hole in the ArvinMaricopa area. No chemical analyses were made on 

samples from this hole. 

TABLE 18.-Clay minerals in fine-grained sediments from Lakeview 

test hole, Arvin-Maricopa area 

[Determined with the assistance of F. P. Naugler and J. B. Corliss] 

Clay minerals (estimated parts per ten) 

Depth below land surface (feet) 

Montmorillonite Illite 

Chlorite and 

kaolinite-type mineral! 

---·-·----------------------1-------

336------------~------- 8 1 1 c 400____________________ 7 2 1 B 533____________________ 7 1 2 B 664____________________ 8 1 1 D 688____________________ 8 1 I D 831____________________ 8 Trace 1 D 1, 150____________________ 9 Trace 1 B 

1,459____________________ 6 2 2 B 

~ean______________ 7~ 134 134 

1 Letters refer to type of X-ray diffraction pattern shown in fig. 40. 

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--------------------------

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C80 MECHANICS OF AQUIFER SYSTEMS 

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Page 

A 

Acknowledgments____________________________ CS 

Alameda Creek (No.8), clay minerals ________ 45,77 

Alluvial-fan deposits ____ 5, 7, 8, 13, 16, 17, 21, 27, 30,33 

differences between Tulare-Wasco and Los 

Banos-E:ettleman City areas_____ 21 

distinguishing criteria ____________________ 7,28 

particle sizes __ --------------------- 10, 12, 13, fSO 

relations between median diameter and 

other particle-size measures ____ 16, 17,33 

Amnicola_ --------------------- ________ _______ 9 

Anions, soluble, analyses_____________________ 71 

soluble, relation to pH and total salt 

concentration __ ------------------ 37 

tables of analytical data_------------- 72 

Anticline Ridge __ ----------------------------

Arroyo Ciervo (No.7), clay minerals _________ 20,74 

Artesian pressure, depletion__________________ 2 

Arvin-Maricopa area __ ----------------------- 2, 46 

clay mineral content of sediments________ 45 

location of Lakeview test hole____________ 47 

B 

Bartell, A. J., analyst_ ____________________ 75, 76,77 

Berkland, J. 0., analyst______________________ 77 

Biotite _______________________________ 5, 21, 24, 27,35 

Brewer, Roy, quoted_________________________ 27 

Bull, W. B., cited ____________________________ 16,18 

c 

Calcite _______________________________________ 40,72 

Cantua Creek, exchangeable cations __________ 25,74 

Cantua Creek (Nos. 8, 9), clay minerals ______ 20,74 

Cantua Creek core __ ------------------ 5, 9,53,58, 73 clay minerals _____________________________ 19,73 

core-hole location_________________________ 4 

exchangeable cations _____________________ 25,73 

particle-size distribution____________ 12, 53, 58, 59 

Cations, exchangeable: 

analytical procedures_____________________ 71 

Cantua Creek ____________________________ 25,74 

Little Panoche Creek _________________ 23, 25,74 

Los Banos-Kettleman City area__________ 22 

in modern stream sediments__________ 23 

in subsurface sediments______________ f3 

Los Gatos Creek (Fresno County, No.12) __ 25,74 

Mayfield Slough__________________________ 77 

Panoche Creek_----------------------- 23, 25,74 

relation to cations in associated waters __ 23, 36, 44 

relation to pH ____________________________ £3,36 

San Francisquito Creek__________________ 77 

Santa Clara Valley_______________________ 44 

tables of analytical data__________________ 72 

Tulare-Wasco area________________________ 35 

Cenozoic sedimentary rocks__________________ 5 

Chao, T. T., cited____________________________ 35 

Chert________________________________________ 5, 38 

Chlorite __________________________ 18, 22, 34, 44, 46,69 

Chloritic minerals, minor_____________________ 71 

Clay aggregates______________________________ 8 

Clay-mineral study, analytical procedures____ 65 

tabulated results_________________________ 72 

Clay minerals: 

Alameda Creek (No.8) ___________________ 45,77 

Arroyo Ciervo (No.7) ____________________ 20,74 

Arvin-Maricopa area_____________________ 45 

INDEX 

[Italic page numbers indicate major references] 

Clay minerals-Continued Page 

assemblages_------------- ________ C18, 34, 43,46 

Cantua Creek (Nos. 8, 9) _________________ 20,74 

Coyote Creek _________________________ 41,45, 77 

Coyote Slough (No. 12) __________________ 45,77 

identification criteria_____________________ 67 

ions associated with ___________________ 22,35,44 

Los Banos-Kettleman City area ____ 18,66, 73,74 

Los Gatos Creek (Fresno County, No.12)_ 20,74 

Los Gatos Creek (Santa Clara County, 

No.4) ____________________________ 45,77 

Martinez Creek (No. 11)-------------~---- 20,74 

Mayfield Slough (No.ll) _________________ 45,77 

Moreno Gulch (Nos. 2, 3) _________________ 20,74 

Panoche Creek (Nos. 5, 6) ________________ 20,74 

Salt Creek (No.lO) _______________________ 20,74 

San Francisco Bay_------------------- 41, 45,77 

San Francisquito Creek (Nos. 1, 2) _______ 45,77 

Santa Clara Valley_------------------- 43, 76,77 

sources_------------------- ______ 18, 22, 34, 44,46 

Stevens Creek (No.3) ____________________ 45,77 

total material in sediments _______ - ____ 22, 35, 44 

Tulare-Wasco area ________________________ 34,75 

CM diagrams ________________________ 14, 16, 17,33, 43 

Coast Ranges_----------------------------- __ 21,38 

Collection of samples _________ ---------------- 2, 48 

Compaction ___________________________ 3, 6, 18, 24,47 

Conomos, T. J., analyst______________________ 77 

Corcoran Clay Member of the Tulare Formation, lacustrine deposits ______ 8, 9, 12, 27 

Core-hole sediments, particle-size analyses __ -- 9, 

22,28,41 

Core holes, location and description__________ 3 

Corliss, J. B., analyst_ ____________________ 76, 77,78 

Coyote Creek _____________________________ 38, 40,41 

clay minerals __________________________ 41,45, 77 

Coyote Slough (No. 12), clay minerals ________ 45,77 

Cretaceous sedimentary rocks________________ 5 

Cutans______ ____ __________ _____________ ______ 27 

D 

Davis, G. H., cited ________________________ 23,24,50 

Deltaic deposits______________________________ 6, 9 

distinguishing criteria____________________ 7 

particle sizes _____________________________ 10, 12 

Deposition of sediments, rates________________ 41 

relation to particle-size measures ____ 13, 16, 33,43 

textural evidence of processes_____________ 7, 27 

Deposits, alluvial-fan_ 5, 7, 8, 13, 16, 17, 21, 27, 28, 30,33 

alluvial-fan, differences between TulareWasco and Los Banos-Kettleman 

City areas________________________ 27 

particle sizes ______________ 10, 12, 13, 16, 30,33 

criteria for distinguishing principal types_ 6 

deltaic____________________________________ 6, 9 

particle sizes __________________________ 10, 12 

estuarine, absence of______________________ 40 

flood-plain ____________________ 5, 7,9, 11,16,27,28 

particle sizes ____________________ 10, 12, 16,30 

lacustrine ______________________________ 5, 8, 9, 27 

Corcoran Clay Member of the Tulare 

Formation _______________________ _ 

particle sizes _______________________ 10, 12,30 

marine ________________________________ 21, 24,28 

particle sizes _______________________ 29, 30,33 

mudflow _ _ _ _ ______ ___ _____ ______ _______ __ 16 

types ___________________________________ 5, 24,38 

Page 

Diablo Range _____________ C3,5,8,9,11,17,20,22,38 

sand description _____________________ ----- 5 

Diamond, Sidney, cited._____________________ 66 

Diatoms, lacustrine deposits__________________ 8 

marine deposits ___________________________ 24,28 

Diepenbrock, Alex, cited _____________________ 24,31 

E 

Ephemeral streams, defined._________________ 8 

Etchegoin Formation_________________________ 3, 5 

F 

Fabric of fine-grained sediments______________ 7,8 

Fang, S.C., cited____________________________ 35 

Flood-plain deposits ___________ 5, 7, 9, 11, 16, 17,27,30 

distinguishing criteria _____ ------.--------- 7, 28 particle sizes ___________________________ 10,12,30 

relations between median diameter and 

other particle-size measures___ 17 

Fluminicola _____ ________________________ --- _-- 9, 40 

yatesiana _________________________________ 40,41 

Fossiliferous silts ______________________ --- ___ - 40 

Fossils: 

Amnicola ___________ ---------------------- 9 

Fluminicola ______ _____________________ ---- 9, 40 

yatesiana _____________________________ 40,41 

Gyraulus ________________________________ - 40 

Helisoma _________________________ -------- 40 

Littorina _____ _________ -___ ----------------

Lymnaea ____________ ---------------------

Menetus __ --------------------------------

9 

40 

40 

Pisidium_________________________________ 40 

Franciscan Formation ________________ 5,18,22,38,44 

Fresno County __________________ ------------- 3,18 

Frost, I. C., analyst_ _________________________ 73,74 

G 

Gastropods ________ --------------------------- 9,40 

Geib, B. H., analyst_ ________________________ _ 77 

Gilbert, C. M., cited _________________________ _ 

Glaucophane __________ --- ____ ---------------- 38 

Granitic 18 rocks ____ ---------------------

Graywackes ____________________________ ------ 18,38 

Green, J. H., cited _____ -----

Guadalupe River _____ ------------------------

38 

38 

Gypsum_-------------------------------- --- 38,72 

Oyraulu.L _--- -------------

H 

Halloysite ________ ---

Hansen, Edelle, analyst_----

Harward, M. E., Cited_ 

Helisoma ___ __ _ 

Hilton, G. S., cited _____ _ 

40 

- 21,35 

77 

35 

40 

3S 

Hornblende_____________ - 5,24 

Huffman, Claude, analyst_ ________________ 73, 74,75 

Huron core ____________________ 6, 9, 12, 23, 55, 58,74 

clay minerals _____________________________ 19,73 

exchangeable cations __ ------------------- 25,73 

particle-size distribution_------------ 12, 55, 58, 59 

Hydrodynamic sorting_---------------------- 15 

C81 
C82 

Page. 

Illite _____ ---------------- CIS, 21, 22, 34, 41, 44, 46, 68 

Illite-montmorillonite mixture, low-grade_____ 18, 

34,44,69 

Inman, D. L., cited _________ ~---------------- 14,49 

Ions associated with clay minerals __ . 18, 22, 34, 35,43 

J 

Janda, R. J., cited __________________________ 9, 21,34 

K 

Kaolinite _____________________________________ 21, 34 

Kaolinite-type mineraL _____________ 18, 22, 34, 46,69 

Kinter, E. B., cited__________________________ 66 

Klausing, R. L., cited________________________ 38 

Knoxville Formation _________________________ 38, 44 

Krumbein, W. C., cited ___________________ 11,49,50 

L 

Lacustrine deposits __________________ _ 5, 8, 9, 24, 27, 30 

Corcoran Clay Member of the Tulare Formation __ --------------------- 8, 9, 12,27 

distinguishing criteria____________________ 7 

particle sizes ___________________________ 10, 12, 30 

Lakeview test hole, clay minerals _____________ 46,78 

location__________________________________ 47 

Lipp, H. H., analyst_ ________________________ 73,74 

Little Panoche Creek _________________________ 22,58 

alluvial fan_______________________________ 18 

cation composition of water samples______ 23 

clay minerals __________________________ 18, 20,74 

exchangeable cations __________________ 23, 25,74 

Little Panoche drainage basin________________ 18 

Littorina____ __ _ _ _ _ __ __ __ _ _ _ _ _ __ _ ____ __ _ __ _ _ _ _ _ 9 

Lofgren, B. E., cited_________________________ 24 

Los Banos-Kettleman City area______________ 2, 

3, 5, 6, 7, 8, 16, 17, 1R, 22, 24, 29, 5.'J, 66 

age of sediments__________________________ 3 

alluvial-fan deposits ______________________ 8,17 

cation composition of streams and ground 

waters____________________________ 23 

clay-mineral composition of sediments_ 18, 73,74 

core-hole locations________________________ 4 

deltaic deposits________________ ____ 9 

deposition of sediments _________________ 6, 17,21 

exchangeable cations on clays __________ 23, 73,74 

flood-plain deposits_______________________ 9,17 

lacustrine deposits___ ____________________ 9 

particle sizes ______________________ 9, 13, 51, 58,59 

principal types of deposits________________ 5 

sediments________________________________ 3 

sources of sediments______________________ 5 

Los Gatos Creek (Fresno County, No. 12), 

clay minerals _____________________ 20,74 

exchangeable cations ______________________ 25,74 

Los Gatos Creek (Santa Clara County, No.4), 

clay minerals_____ _ _____ 45,77 

Lymnaea____ _______________ ________________ 40 

M 

McClelland, E. J., cited ______ _ 38 

Manzanares, Toribio, Jr., analyst 76,77 

Marine deposits_________ _ ___ 21,24 

distinguishing criteria___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 28 

particle sizes ______________________________ 30,31 

relations between median diameter and 

other particle-size measures_______ 33 

Martinez Creek (No. 11), clay minerals ______ 20,74 

Mayfield Slough, exchangeable cations________ 77 

Mayfield Slough (No. 11), clay minerals ______ 45,77 

Mendota core _________________ 5, 9, 12, 21, 22,51, 58,73 

clay minerals________________ _ ___ 19,73 

core-hole location____________ ____________ 4 

exchangeable cations _____________________ 25,73 

particle-size distribution ______________ 12, 51, 58 

1\J:enetus_ _ _ __ ___ ____ ________ ____ ___ __ __ _____ __ 40 

Metamorphic rocks ___________________________ 18,24 

Miller, R. E., cited___________________________ 9 

INDEX 

Page 

Mineral species, estimation of relative proportions_____________________________ C71 

Montmorillonite _______ 5, 18, 20, 22, 34, 41, 43, 46, 48,67 sources _____ ,______________________________ 18 

alteration of volcanic materiaL_______ 18 

Montmorillonite-illite, mixed-layer _________ 18, 22, 68 

Moreno Gulch (Nos. 2, 3), clay minerals _____ 20,74 

Mudfl.ow deposits_____________________________ 16 

N 

Naugler, F. P., analyst_______________________ 7R 

Nelson, B. W., cited__________________________ 22 

0 

Oro Lorna core __________________ 5, 9, 18, 22, 23, 58,73 

clay minerals __________________________ 18, 19,73 

core-hole location_________________________ 4 

exchangeable cations ______________________ 25,73 

particle sizes______________________________ 58 

Oxyhornblende_____ ___ ____ __ _______ ____ ______ 38 

p 

Panoche Creek, cation composition of water 

samples ____ ---------------------- 23,58 

exchangeable cations ___________________ 23,25, 74 

Panache Creek (Nos. 5, 6), clay minerals ____ 20,74 

Particle-size distribution, CM diagrams_ 14, 16, 33,43 

descriptive measures______________________ 49 

interrelations of particle-size measures __ 16, 32, 43 

measures of central tendency_____________ 11 

median diameters________________________ 11, 

13, 14, 16, 29,31, 32, 33, 42, 43,49 

modal diameters ____________________ 11,29,31,42 

relations to depositional history of sediments____________________________ 13 

skewness _________ 11, 14, 16, 29, 31,33, 42, 43, 49,50 

sorting ___ ----------- 11, 14, 16, 29,31, 33, 42, 43,49 

Particle sizes, analytical procedures___________ 48 

Los Banos-Kettleman City area ________ 9,51, 58 

sampling __________________ --------------- 3, 48 

Santa Clara Valley _______________________ 41,63 

spatial distribution in cores ____________ 12,31,42 

tables of data_____________________________ 50 

Tulare-Wasco area ________________________ 27,60 

Passega, Renato, cited _____________________ 14,15,49 

Permeability, relation to grain size___________ 13 

Petrologic study, summary of results_________ 46 

Pettijohn, F. J., cited ________________________ 11,50 

pH, effect on cation exchange of clays _________ 23,36 

measurement_____________________________ 72 

pH environment of the San Joaquin Valley 

sediments________________________ 21 

Phi, defined__________________________________ 49 

Pisidium_ _ _ _ _ ____ _______ _______ __________ ____ 40 

Pixley area ______________ --------------------- 36 

Pixley core _________________ 22, 24, 27, 29,32,34,60, 75 

chemical composition of nearby ground 

water_____________________________ 36 

clay minerals _____________________________ 34,75 

core-hole location_________________________ 26 

exchangeable cations ______________________ 35,75 

particle sizes ______________________________ 32,60 

Pliocene sandstones__________________________ 5 

Poland, J. F., cited ________________________ 23,24,38 

Pollard, W. C., analyst_______________________ 77 

Porosity______________________________________ 8, 47 

Potassium-argon dating of volcanic ash_______ 9 

Pratt, P. F., cited____________________________ 36 

Purposes of report____________________________ 2 

Pyrite __________________________________ 7, 23, 28,38 

R 

Resistivity logs ___________________ 12, 13, 26, 29, 32,43 

Review of previous work of sedimentologists__ 14 

Richgrove area_______________________________ 36 

Page 

Richgrove core___________ C24, 27, 29, 32, 33, 35, 38,61 

chemical composition of nearby ground 

waters____________________________ 36 

clay minerals _____________________________ 34,75 

core-hole location_________________________ 26 

exchangeable cations ______________________ 35,75 

particle sizes ___________________________ 31, 32,61 

soluble salts and anions___________________ 37 

Roy, Rustum, cited _________________________ _ 

Rubin, Meyer, cited _________________________ _ 

s 

22 

41 

Salt Creek (No.IO), clay minerals ____________ 20,74 

Salts, San Jose core___________________________ 40 

Sunnyvale core___________________________ 40 

San Emigdlo Mountains______________________ 46 

San Francisco area___________________________ 18 

San Francisco Bay, clay minerals _________ 41,45, 77 

San Francisquito Creek, exchangeable cations_ 77 

San Francisquito Creek (Nos. 1, 2), clay 

minerals __________________________ 45,77 

San Joaquin Formation_--------------------- 3, 5 

San Joaquin River basin_____________________ 21 

San Joaquin Valley ________________________ 3, 5, 8,18 

pH environment of sediments____________ 21 

San Jose area, deposition rate_________________ 41 

San Jose core ______________________________ 40,65, 76 

chemical composition of nearby ground 

water_--------------------------- 78 clay minerals _____________________________ 44,76 

core-hole location_________________________ 39 

date of, by carbon-14 analysis_____________ 41 

exchangeable cations __ ------------------- 46,76 

particle sizes _____________________________ 43,65 

Sands, andesitic______________________________ 5 

arkosic___________________________________ 5 

Arvin-Maricopa area __ ------------------- 46 

Diablo Range____________________________ 5 

Richgrove core___________________________ 24 

San Jose core ______ ----------------------- 38 

Sunnyvale core___________________________ 38 

Santa Clara County__________________________ 38 

Santa Clara Valley ________________ 2,24,39,41,63, 77 

age of sediments __________ --~---------- 38, 40,41 

chemical composition of ground waters_ 44, 77, 78 

clay-mineral assemblage__________________ 43 

core-hole locations________________________ 39 

exchangeable cations on clays_____________ 44 

particle sizes _____ -~- _________________ -___ 41 

rates of deposition_----------------------- 41 sediments _______ .. ________________________ 38 

soils______________________________________ 39 

source of sediments_______________________ 38 

types of deposits_------------------------ 38 

Santa Cruz Range_-------------------------- 38 

Santa Margarita Formation __________________ 24,31 

Sedimentary rocks___________________________ 18 

Serpentine ___________________________ 5, 22, 24, 38,46 

Shepard, F. P., cited_________________________ 9 

Sierra Nevada ____________________ 3, 5, 9, 11, 17, 21,24 

Sigvaldason, G. E., cited_____________________ 22 

Skewness, Bowley's measure of_______________ 50 

Soil textures__________________ _ _ _ _ __ _____ __ __ 27 

Soils, modern alluviaL----------------------- 39 

older alluviaL________________________ 40 

Sokula, Ignacio, analyst______________________ 77 

Sources of clay minerals _____________ 18,22,34, 44,46 

Sources of sediments ________________________ 5,24,38 

Starkey, H. C., analyst_ _____________ 73, 74, 75, 76,77 

Stevens Creek (No.3), clay minerals _________ 45,77 

Stream sediments, exchangeable cations______ 23 

Sulfate ________________________________ - _____ - 23 

in marine siltstones_______________________ 37 

origin_________________________________ 38 

Sulfides, authigenic ____________________ 7, 9, 28, 37,38 

Summary of results___________________________ 46 
Page 

Sunnyvale core _______________________ C40,41,63, 76 

chemical composition of nearby ground 

waters____________________________ 77 

clay minerals _____________________________ 44,76 

core-hole location_________________________ 39 

date of, from fossil remains_______________ 41 

exchangeable cations ______________________ 46,76 

particle sizes ______________________________ 43,63 

T 

Taylor, D. W ., fossils identified by___________ 40 

Trask, P. D., cited___________________________ 50 

Tulare County, core holes____________________ 24 

Tulare Formation ___________________________ 3, 5, 21 

andesitic sands___________________________ 5 

Cmcoran Clay Member, lacustrine deposits_ 8, 12, 27 

waterlaid deposits________________________ 5 

INDEX C83 

Page V Page 

Tulare-Wasco area __________________ C2, 22,33,35,60 Vermiculite ___ ---- _______________________ C21, 34,67 

age of sediments__________________________ 24 Villarruz, Primo, analyst_____________________ 78 

alluvial-fan deposits ___________________ 21, 27,33 

chemical composition of ground waters ___ 36,38 

clay-mineral assemblages _________________ 34,75 

core-hole locations_----------------------- 26 

Volcanic ash, potassium-argon dating oL _ _ _ _ _ 9 

Volcanic glass __ ------------------------------ 24 

Volcanic materiaL _________________________ 5, 18,24 

Volcanic rocks________________________________ 18 

exchangeable cations on clays _____________ 35,75 w lacustrine and flood-plain deposits________ 27 

marine deposits ________________________ 21,24,33 

nonmarine sediments, description_ _ _ _ _ _ _ _ 29 

particle sizes ______________________________ 27, 60 

principal types of deposits _____ ~---------- 24, 2i 

Waugh, A. E., cited _______ J__________________ 50 

White, D. E., cited ___________________________ 22,38 

Wiklander, Lambert, cited____________________ 36 

Williams, Rowel, cited _______________________ _ 

sediments_------------------------------- 24 X source of deposits _________________________ 24,27 

Turner, F. J., cited ____ ,_______________________ 5 X-ray diffraction, procedure__________________ 66 

U. S. GOVERNMENT PRINTING OFFICE: 1967 0- 232-511