Chemical Weathering, Soil Development, 

and Geochemical Fractionation in a Part 

of the White Mountains, Mono and 

Inyo Counties, California

GEOLOGICAL SURVEY PROFESSIONAL PAPER 352-J
Chemical Weathering, Soil Development, 

and Geochemical Fractionation in a Part 

of the White Mountains, Mono and 

Inyo Counties, California

By DENIS E. MARCHAND

EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

GEOLOGICAL SURVEY PROFESSIONAL PAPER 352-J

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1974
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 73-600361

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

Washington, D.C. 20402 - Price $1-35 (paper cover) 

Stock Number 2401-02484
CONTENTS

Page

Abstract ________________________________ 379

Introduction _____________________________ 379

Study area _______________________________ 381

Location and description ___________________ 381

Previous work in the region __________________ 382

Climate _____________________________ 382

Vegetation ____________________________ 384

Geology _____________________________ 385

Chemical weathering and soil development___________ 388

Method of approach_______________________ 388

Field methods _________________________ 388

Laboratory methods _____________________ 388

Description of soils _______________________ 389

Clarification of terms ___________________ 389

Reed Dolomite soils____________________ 390

Adamellite soils of Sage Hen Flat ___________ 390

Basalt soils _________________________ 391

Andrews Mountain sandstone soils __________ 391

Soil contamination _______________________ 392

Physical weathering _____________________ 392

Reed Dolomite _______________________ 392

Adamellite of Sage Hen Flat ______________ 393

Mechanisms of disintegration ______________ 394

Chemical weathering _____________________ 395

Changes in the solid phases _______________ 395

Mineralogical changes _______________ 395

Reed Dolomite __________________ 395

Adamellite of Sage Hen Flat ________ 396

Electron microprobe studies of adamellite

mineral weathering _________ 398 

Biotites __________________ 398 

Feldspars ____________________ 400 

Other minerals______________ _ 400

Page

Chemical weathering and soil development Continued 

Chemical weathering Continued

Changes in the solid phases Continued

Chemical changes from bedrock to soil ______ 400

Reed Dolomite __________________ 401

Adamellite of Sage Hen Flat ________ 403

Changes in the liquid phase _______________ 405

Chemical composition of precipitation ______ 405

Chemical composition of soil water __ __406

Soil pH ________._______._____. 406

Exchangeable cations ______________ _ 406

Chemical composition of spring waters ______ 407 

Waters related in part to the

Reed Dolomite ________________ 407 

Waters related largely to the adamellite of

Sage Hen Flat __.______________ 408 

Analysis of chemical changes ___ ____ __ __408

Relative mobilities _______________ 408 

Stability with respect to solid

and gas phases ________________ 409 

Relation of soil water to precipitation 

and spring waters _____ _ 411

Chemical fractionation in the bedrock-soil-water-plant 

system________________________________413

Summary and discussion _____________ ______ 416

Weathering of Reed Dolomite ________________ 417 

Weathering of adamellite of Sage Hen Flat ________ 417 

General weathering relations ________________ 418

References cited __ ___ 418

Supplemental information Methods, reproducibility, 

and accuracy ___ ___ 422

ILLUSTRATIONS

Page

FIGURE 269. Diagram showing reversible, irreversible, and cyclical processes associated with weathering and erosion ______ 380

270. Map of east-central California and adjacent part of Nevada, indicating location of the study area _________ __ 381

271. Photograph showing part of the upland surface in the White Mountains __________________ __________ 381

272. Map of generalized topography of a part of the southern White Mountains _________________ __ _ 381

273. Photograph showing North Sage Hen Flat auxiliary weather station and dust trap ___________ 383

274. Graph showing maximum and minimum temperature and relative evaporation rates at Crooked Creek Laboratory

and five auxiliary weather stations ______________________ - 384

275. Graph showing precipitation recorded at Crooked Creek Laboratory and at five auxiliary weather stations 384

276. Photograph showing vegetational contrast between dolomite outcrops and colluvium and sandstone colluvium 385

277. Generalized geologic map of the study area _____________________________ _____ __________ 386

278. Photograph showing view north across Sage Hen Flat, showing degraded White Mountain erosion surface and outcrop

areas of adamellite of Sage Hen Flat, Reed Dolomite, and Andrews Mountain sandstone _____ 387

279. Photograph showing view east from Sage Hen Flat, showing resistant basalt capping less resistant metasediments and

granitic intrusive rock ______________________________________________ _______ 387

III
IV CONTENTS

Page

FIGURE 280. Photograph showing exposures of reworked rhyolitic ash interbedded with terrace alluvium along Croloked Creek 387 

281 -284. Maps showing:

281. Depth of soil and colluvium at planetable map site R-l, Reed Dolomite, 10,600 feet ___________ 389

282. Depth of soil and colluvium at planetable map site R-2, Reed Dolomite, 11,200 feet ______________ 390

283. Depth of soil and colluvium at planetable map site S-l, adamellite of Sage Hen Flat _ _. ___ 390

284. Depth of soil and colluvium at planetable map site B-l. on basalt _______________,_______ 391

285. Photograph showing Reed Dolomite soil pit ________________________________ 391

286. Photograph showing soil pit in'adamellite of Sage Hen Flat ______________________ - - 391

287. Graph showing cumulative grain size frequency curves for dolomite soils and comparison with ranges i|n bedrock grain

size ___________________________________________________________ 392

288. Diagram showing gravel-sand-silt and clay distribution for soil above the C horizon __________ ______ 392

289. Diagram showing sand-silt-clay distribution for soil above the C horizon __________________ ______ 393

290. Photograph of weathered adamellite outcrop on Sage Hen Flat ________________________ 393

291. Graph showing cumulative grain size frequency curves for adamellite soils and comparison with ranges of bedrock grain

size ___________________________________________________________________ 394

292. Photomicrographs showing fresh, crushed bedrock dolomite and etched, embayed, altered soil dolomite grain ____ 395

293. Photomicrographs showing fresh, crushed bedrock talc and soil talc grains ____________________________ 396

294. Diagram showing mineral weathering sequence in Reed Dolomite soils, in order of decreasing resistance ___ 396

295. Photomicrograph of weathered grains in adamellite soil thin section __________________ 397

296. Photomicrograph of soil biotite grains ___________________________________________________ 397

297. Diagram showing mineral weathering sequence in adamellite soils of Sage Hen Flat in ord|er of decreasing

resistance _____________________________________________________ ._________ 398 

298-301. Graphs showing:

298. Electron microprobe traverses normal to (001) cleavage of two soil biotite grains _______h _____ __ __ 399

299. Electron microprobe traverses parallel to (001) cleavage of two soil biotite grains _________________ 399

300. Electron microprobe analyses of 10 parts of a single plagioclase grain _____________ ______ 400

301. Percentage chemical losses for the indicated Reed Dolomite and adamellite soils of Sage Hen Flat with respect to bedrock ___________________________________________ __________ 402 

302. Photograph of rock saw chips showing weathering rind on spheroidally weathered dolomite analyzed by electron

microprobe _______________________________________________________________ 403 

303 -308. Graphs showing:

303. Electron microprobe transect showing Ca, Mg, and Fe variation across an alteration rind in spheroidally

weathered Reed Dolomite _____________________________________,__________ 403

304. Electron microprobe transect for Ca, Mg, and Mn across same dolomite weathering rindl __________ 403

305. Mineral percentage changes with respect to bedrock in two size fractions of a relatively uncontaminated

adamellite soil ____________________________________________ __________ 404

306. Relative mobilities for eight elements in spring waters related to adamellite _________ 409

307. Stability diagram for Na silicates ____________________________________ 411

308. Stability diagram for K silicates _____________________________________ __________ 411

309. Compositional diagram showing progressive cation changes from precipitation water to soil and spring waters related

to Reed Dolomite ________________________________________________ __________ 412

310. Compositional diagram showing progressive cation changes from precipitation water to soil and spring waters related

to adamellite __________________________________________________ __________ 412 

311-314- Graphs showing:

311. Mg/Fe and Ca/Fe ratio comparisons of waters related to adamellite ______________ __________ 413

312. Silica-cation ratio comparisons of adamellite-related waters ____________________ ______ 413

313. Comparison of elemental and total concentrations in soil, soil water, colloidal exchange, and plants 415

314. Fractionation of nine elements in the adamellite bedrock-soil-water-plant system _______i______ 416

315. Diagram of flowsheet for laboratory treatment of bedrock samples ______________________,______ 422

316. Diagram of flowsheet for laboratory treatment of soil samples _________________________ ______ -- 422

TABLES

Page

TABLE 1. Summary of climatic means and extremes from Crooked Creek and Mount Barcroft Laboratories 383

2. Types of information obtained at Crooked Creek Laboratory and five auxiliary weather stations during the period

June 1966 to August 1967 ____________________________________________ 383

3. Estimated precision of measurement for some analytical quantities discussed in this paper 389

4. Mineral weight percentages in five Reed Dolomite bedrock samples __ - . 395

5. Mineral weight percentages in five adamellite bedrock samples from Sage Hen Flat 396

6. Chemical compositions of 10 major minerals in the adamellite of Sage Hen Flat __ 397

7. Layer silicates in silt and clay fractions of some adamellite soils _________ 398

8. Averaged electron microprobe analyses of fresh and weathered biotites 399
CONTENTS V

Page

TABLE 9. Individual electron microprobe analyses of altered and relatively fresh parts of soil biotites ______ -i___-_ 399

10. Averaged electron microprobe analyses of feldspars from fresh adamellite bedrock, grus, and soils ,_ 400

11. Electron microprobe analyses of four minerals from fresh adamellite of Sage Hen Flat and from derived sioil ________ 400

12. Chemical analyses of Reed Dolomite bedrock and soils ________________________________________ 401

13. Chemical compositions of minerals and glass in soils used to correct chemical analyses ___ > 402

14. Absolute losses of chemical constituents from bedrock to soil, assuming constant Zr percentage _____ ______ ___ 402

15. Averaged values for X-ray fluorescence chemical analyses of adamellite bedrock and soils from Sage Hetn Flat ______ 404

16. Adamellite sample 94 bedrock chemical analysis and adjustment of <2-mm-soil analysis for ash and local contamination

by biotite and hornblende ____________________________________________ _____ __ 405

17. Chemical analyses of precipitation collected near Crooked Creek Station and comparison with analyses of snow from

the east slope of the Sierra Nevada ____________________________________ 406

18. Chemical constituents in water saturation extracts of two groups of White Mountains soils __ 406

19. Mean values for total exchangeable cations, percentage exchangeable cations, and pH in Reed Dolomite and adamellite

soils of Sage Hen Flat ______________________________________________ ______ - 407

20. Field and laboratory analytical data for two natural waters associated in part with the Reed Dolomite 407

21. Field and laboratory analytical data for two natural waters associated with the adamellite of Sage Hen Flat 408

22. Relative mobilities for four elements in Cottonwood Spring waters _______________ '- 409

23. Degree of saturation with respect to calcite and dolomite for four spring waters _______ ___\________________ 410

24. Partial pressures of carbon dioxide in four spring waters and a comparison with atmosphericiPCOa 410

25. Chemical composition of some major plant species on Reed Dolomite and adamellite of Sage Hen Flat __ 414

26. Fractionation by plants with respect to soil water for seven elements in adamellite and dolomite terranes 416

27. Reproducibility of X-ray fluorescence analyses ____________________________ 423

28. Comparison of analytical results for some adamellite and Reed Dolomite samples, as analyzed by X-ray fluorescence,

wet chemistry, and flame photometry ______________________________ -- 423

29. Variation in measured parameters of four White Mountains soil types _ 424

EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

CHEMICAL WEATHERING, SOIL DEVELOPMENT, AND

GEOCHEMICAL FRACTIONATION IN A PART OF THE

WHITE MOUNTAINS, MONO AND INYO COUNTIES, CALIFORNIA

By DENIS E. MARCHAND

ABSTRACT

The White Mountain erosion surface truncates a variety of late 

Precambrian and Cambrian metasedimentary units and several 

Mesozoic plutonic bodies; it is overlain by Tertiary basalts. Present 

climatic gradients in the 30-square-mile study area are not 

pronounced, and thus weathering of diverse lithologies under a 

reasonably uniform semiarid subalpine environment may be studied 

here. The local vegetation, consisting primarily of sagebrush, 

bristlecone and limber pine, and associated perennial herbs, is 

relatively sparse and shows marked discontinuities across geologic 

contacts. Soils in the region are immature lithosols, usually less than 

1 foot deep, but better developed soils may have formed prior to or 

during late Tertiary uplift, only to be stripped by subsequent erosion. 

A reworked rhyolitic late Pleistocene ash and local windblown 

fragments are abundant soil contaminants and complicate efforts to 

decipher mineralogical and chemical changes due to weathering.

Rock weathering in this region appears to be primarily a function of 

mineral composition and of the density and degree of physical rock 

flaws which serve as avenues for penetrating fluids. Physical 

breakdown, which tends to precede chemical weathering, seems as 

closely related to lithologic features as to climate. Since erosion is 

aided by rapid weathering, easily disintegrated rock types such as 

course-grained carbonate and adamellite and fissile shale have eroded 

to topographic lows while slow-weathering fine-grained carbonate, 

quartzose sandstone, basalt, aplitic dikes, and mafic inclusions have 

resisted erosion.

Reed Dolomite, a Precambrian unit, weathers by frost riving to 

polycrystalline, cleavage-bounded grains, except where the presence 

of thermally recrystallized rock has led to production of singlecrystal fragments. Mineral weathering occurs in the sequence dolomite » tremolite, epidote > talc, K-feldspar, biotite ^ apatite > 

quartz and ilmenite. Percentage chemical losses from bedrock to soil 

are Mg > Ca > Sr > Mn ~ Fe, for carbonate-constituent elements. 

Authigenic calcite is apparently precipitated in the soil during dry 

seasons and partially dissolved during wet periods. Spring waters 

related in part to the dolomite show relative mobilities of Mg > Ca > 

Fe > Mn. Ion-activity product computations indicate that these 

waters are undersaturated with respect to both calcite and dolomite. 

PCO2 exceeds atmospheric values by over an order of magnitude and 

those of adamellite-derived waters by several times. Dolomite soil 

water extracts appear closer in pH to the spring waters than to rain or 

snow, although the soil water composition is obviously quite different 

from either of these fluids. Chemical changes in both solid and liquid 

phases related to the dolomite appear to begin along with physical 

breakdown in the early stages of rock weathering.

Adamellite of Sage Hen Flat weathers by frost riving along 

intergranular weaknesses, causing boulder exfoliation and 

accumulation of grus. This coarse material, largely unaltered except

for minor Fe oxidation, later undergoes important chemical 

breakdown during its transformation to finer sized particles. Primary 

minerals weather in the sequence plagioclase (An2 s_3o) > 

hornblende > biotite, epidote > microcline, plagioclase (Anio_i5), 

allanite > apatite, chlorite, magnetite > ilmenite, muscovite, quartz, 

sphene > zircon, resulting in percentage chemical losses from fresh

?

rock to soil in the sequence Rb > Na =: K ~ Mg > Sr > Mn ~ Ca > 

Ba > Si > Al » Fe > Ti. 1 Kaolinite, and possibly some vermiculite, 

is forming from feldspar, biotite, and other silicates. Microprobe

?

analyses of biotite indicate losses in the sequence Ba > K > Mg > 

Fe > Si > Al; cations having eightfold to twelvefold coordination are 

most readily lost, then cations in octahedral coordination, and finally 

ions in sixfold and fourfold coordination. Microclines reveal losses of 

Na and K, and plagioclases show changes implying removal of Na > 

Ca > Si > Al. Water saturation extracts from adamellite soils are 

distinct in composition from rain and snow water and from spring 

water in adamellite terrane. Relative mobilities of dissolved 

constituents in adamellite ground waters indicate changes with 

regard to bedrock of Ca > Mg ~ Na » Si ~ K ^ Mn x Fe > Al. 

Owing to plant extraction, K and Al mobilities may be lower than 

bedrock-to-soil losses would suggest. High Ca and Mg mobilities could 

result from solution of carbonate grains blown into the soils.

Chemical equilibrium does not exist in the natural waters studied, 

but steady-state conditions are closely approximated in spring waters. 

Contact with weathering rock over a considerable space-time interval 

is apparently necessary for the achievement of a steady state, but this 

interval may decrease for mobile constituents in readily weathered 

minerals. The chemistry of spring waters related to all lithologies 

studied appears very sensitive to differences in source material.

Nine elements released by weathering appear to apportion 

themselves between vegetation, colloidal exchange, and solution as 

follows: Na, soln » exch > veg; Si, soln » veg; Ca, exch > soln > 

veg; Mg, exch > soln = veg; K, veg 5S> soln > exch; Fe, Mn, P, veg » 

soln; Al, veg 5S*> soln.

INTRODUCTION

Bedrock, soil, vegetation, natural waters, and the 

atmosphere are interrelated by a highly complex system of reactions and processes, some of which are shown 

in figure 269. To adequately understand such a system, 

a broad investigation is necessary, including study of 

the many related and potentially significant aspects. It

1. A question mark is used in conjunction with greater than or less than symbols in this 

paper to indicate uncertain position in the sequence.

379
380 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

VEGETATION1 0 S P H E R E

FOREIGN

LITHIC

MATERIAL

Dissolved 

solids 1 

and 

gases

W AT E R 1

PRECIPITATES

FK.I RE 269. Some reversible, irreversible, and cyclical processes associated with weathering and erosion. Footnotes refer to data given in this and other papers: irTotal or partial chemical analysis; 2Physical analysis; 3Rate evaluation; 4Physical analysis and rate evaluation (data in Marchand, 1970); 5Rate evaluation (data in Marchand, 1971).

is impossible, for example, to clearly comprehend the 

transformation of bedrock into soil by studying changes 

in the mineral phases alone, for weathering involves 

important alteration of liquid and gas phases in contact 

with the minerals as well. This paper constitutes the 

fourth in a series of vegetational, erosional, and weathering studies in the southern White Mountains of eastern California (Marchand, 1970,1971, 1973). The focus 

here is primarily on the chemical weathering of two 

widely distributed rock types, dolomite and adamellite, 

utilizing chemical and physical data from all of the five 

system components mentioned. Chemical analyses of 

bedrock, soils, plants, and natural waters permit estimates of the direction and magnitude of chemical fractionation in parts of the geochemical system described 

in figure 269.

The upland surface of the White Mountains, truncating a diversity of sedimentary and plutonic bodies and 

overlain locally by basalt, provides an excellent area in 

which to study the extent, sequence, and processes of 

weathering and soil development applied to many 

lithologies in a semiarid, subalpine environment. 

Quantitative chemical weathering studies have previously been largely confined to tropical or humid temperate regions, for example, Mead (1915), Goldich 

(1938), Cady (1951), Sherman and Uehera (1956), Hay 

(1959), and Wolfenden (1965). In such areas weathering 

has proceeded to such an extent that initial trends are 

difficult or impossible to recognize. Soils in the White 

Mountains are immature and clearly illustrate some of 

the early stages of the weathering process.

Gerald Osborn and Francis H. Brown assisted with 

sample collection and planetable mapping during the 

summer of 1966. J. Ross Wagner aided in preparing 

X-ray fluorescence pellets of bedrock and soil samples, 

conducting mineral separations, and in determining 

many physical and chemical soil parameters. Electron 

microprobe studies were conducted by Lary K. Burns. 

Joaquim Hampel determined Na and K in eight bedrock 

and soil samples by flame photometer. Barbara Lewis 

and James Clayton analyzed plant materials for inorganic constituents.

This paper represents a major portion of a Ph. D. 

dissertation carried out at the University of California, 

Berkeley, and financially supported by the U.S. Geological Survey. Many members of the Survey, especially
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 381

Ivan Barnes, John Hem, and Edward J. Helley, rendered indispensable aid and advice. The manuscript in 

its various stages of preparation was aided by the critical reading of F. J. Kleinhampl, John D. Hem, Richard 

L. Hay, Clyde Wahrhaftig, Peter W. Birkeland, and R. 

R. Tidball.

STUDY AREA

LOCATION AND DESCRIPTION

The White Mountains, often termed the northern 

Inyo Range in older publications, extend from Westgard 

Pass in eastern California north to Montgomery Peak 

(north of map shown in fig. 270) in western Nevada. 

White Mountain Peak (14,246 ft.) is the highest point in 

the range.

The area investigated encompasses approximately 30 

square miles along the crest of the southern White 

Mountains, east of Bishop, Calif., in Mono and Inyo 

Counties (fig. 270). It is characterized by a gently undulating summit upland (fig. 271) sloping southward 

from 11,500 feet near Sheep Mountain to about 10,000 

feet east of Bucks Peak (fig. 272). Summits such as

FIGURE 271. Part of the upland surface in the White Mountains. View north across Big 

Prospector Meadow. Outcrops of Andrews Mountain Member of Campito Formation in 

foreground; white tree-covered exposures in middle and far distance are Reed Dolomite.

Big Prospector Meadow

Count9Line ?age Bucks

»~ M FH,a? Peak

/ I Blanco Mountain

Tes

FIGURE 272. Generalized topography (contours in feet above mean sea level) of a part of the 

southern White Mountains. Posterosion surface deposits shown locally.

FIGURE 270. East-central California and adjacent part of Nevada, indicating location of the 

study area and of the maps shown in figures 272 and 277.
382 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Blanco Mountain, County Line Hill, and Campito 

Mountain stand 500 feet or more above this rolling 

surface. The steep western escarpment of the range, not 

included within the study area, descends 6,000-7,000 

feet in 6 or 7 miles to the floor of the Owens Valley. The 

eastern flank slopes much more gradually, but is incised 

by a series of canyons as much as 1,000 feet deep, which 

drain southwestward to Deep Springs Valley and eastward to Fish Lake Valley.

PREVIOUS WORK IN THE REGION

The brief description of Spurr's (1903, p. 206-212) and 

Knopf's (1918) reconnaissance of the northern Inyo 

Range and eastern Sierra Nevada, which included a 

section on the stratigraphy of the Inyo Range by Edwin 

Kirk, marked the first geological studies of the White 

Mountains. Anderson and Maxson (1935) and Maxson 

(1935) described the physiography and Precambrian 

stratigraphy, respectively, of the northern Inyo Range. 

Recent work in the White Mountains led to publications 

on Precambrian and Cambrian stratigraphy, paleontology, and boundary problems by Nelson and Perry 

(1955), Nelson (1962), Taylor (1966), and Cloud and 

Nelson (1966). Andersen's (1937) arguments for the 

granitization in the formation of the Inyo batholith 

were challenged by Hall (1964) and Emerson (1966). 

McKee and Nash (1967) dated most of the plutonic 

bodies and several metamorphic units in the area by 

K/Ar methods, and Krauskopf (1968) discussed the 

complex intrusive history of the region. Cenozoic volcanism and tectonics were considered by Taylor (1965), 

and Dalrymple (1963) dated Tertiary volcanic rocks on 

the northwest edge of Deep Springs Valley. The Blanco 

Mountain 15-minute quadrangle (Nelson, 1963, 1966) 

and the Mount Barcroft (Krauskopf, 1971) 15-minute 

quadrangles were mapped. Hall (1964), Pittman (1958), 

and Gallick (1964) mapped parts of the White Mountain 

Peak, Mount Barcroft, and Blanco Mountain quadrangles. A general summary of the area's geologic history was provided by Nicholls (1965).

Geomorphic processes in the White Mountains were 

investigated by Powell (1963) and Kesseli and Beaty 

(1959), who studied desert flood conditions, and by 

Beaty (1959, 1960), who discussed slope evolution and 

gullying. LaMarche (1967, 1968) estimated erosion 

rates on the Reed Dolomite from tree-ring data and 

described spheroidal weathering in the carbonate rocks 

of the area.

Several members of the U.S. Geological Survey discussed dissolved constituents in snow (Feth, Rogers, 

and Roberson, 1964) and ground water (Feth, Roberson, 

and Polzer, 1964) in the eastern California region. 

Barnes (1965) studied the geochemistry of Birch Creek, 

which drains the southernmost part of the area and is

similar in some respects to spring waters discussed 

here.

Pace (1963) and Nicholls (1965) summarized climatic 

data collected at the Mount Barcroft and Crooked Creek 

Laboratories of the White Mountain Research Station 

for the decade 1953-62.

CLIMATE

The White Mountains lie in the rain shadow of the 

Sierra Nevada and are generally characterized by a 

cold, dry climate (BWk to BSk of Koppen notation) with 

precipitation occurring largely in the form of snow and 

in sudden summer storms. Mean annual precipitation is 

about 13 inches at Crooked Creek and mean annual 

temperature is approximately 35°F.

Climatic data from the Crooked Creek and Mount 

Barcroft Laboratories (fig. 270) of the White Mountain 

Research Station are summarized in table 1. The 

Crooked Creek Station (10,150 ft.) is located in a valley 

at the approximate center of the study area; the Mt. 

Barcroft Station (12,470 ft.) lies on the upland surface 

about 5-6 miles to the northwest. Both stations are 

situated about 1 mile east of the range crest. Therefore 

climatic data from the two laboratories indicate differences due to elevation and exposure. Precipitation, relative humidity, and wind velocity are higher at Barcroft. 

Temperature and diurnal temperature change are 

greater at Crooked Creek, and a greater proportion of 

the total precipitation occurs as rainfall there. Both 

stations show principal wind directional maximums 

from the west and southwest and a lesser maximum 

from the north or northeast throughout the year. Major 

(1967, p. 119-122) evaluated climatic data at the two 

stations in terms of evapotranspiration and water balance.

Because pronounced geographical climatic gradients 

might produce similar trends in weathering intensities 

or soil development, it was desired to determine 

whether significant east-west or north-south climatic 

gradients exist today in the study area. For this reason 

five auxiliary weather stations (AWS) on the upland 

surface were maintained from June 1966 to August 

1967 (fig. 273). The stations chosen were the Patriarch 

AWS, just south of the Patriarch picnic area; the Campito AWS, on the south flank of Campito Mountain; 

North Sage Hen AWS, on the north edge of Sage Hen 

Flat, above Crooked Creek Station; the Basalt AWS, on 

basalt cappings south of Crooked Creek Canyon; and 

the South Sage Hen AWS, on the southeast flank of 

County Line Hill. (See fig. 277 for locations.) Wind 

measurements recorded at Crooked Creek Laboratory 

were obtained from anemometers near the North Sage 

Hen AWS. All AWS sites were situated on relatively 

level topographic highs at spacings of P/2-3 miles.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 383

TABLE 1. Summary of climatic means and extremes from Crooked Creek (10,150ft) and Mount Barcroft Laboratories (12,470 ft) for the indicated periods

Crooked Creek Laboratory (1949-1965) Crooked Creek Mount Barcroft 

Laboratory Laboratory

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 1949-65 1953-65

Highest maximum temperature

Mean maximum temperature

Mean temperature

Mean minimum temperature

Lowest minimum temperature

Mean diurnal differeno

Largest diurnal difference

Smallest diurnal difference

Mean days 33°F or above

°F 52

_ °F _ 30.1

_°F_ 19.6

_°F _ 9.1

_ °F -21

_°F 21.0

_°F 41

_ °F _ 1

13.8

Mean 8 a.m. relative humidity _ (percent).. 57.5

Mean 8 a.m. barometer ____ _ mn

Mean snowfall

Mean snow depth

Highest snow depth

Mean snow water

Mean rainfall

Mean total precipitation

Mean maximum wind ____ .. _ (ki

Maximum wind direction (percent):

North.

Northeast

East

Southeast

South

Southwest

West _ _ __

Northwest

i Hg _ 517.6

n 15.0

_ n_ 10.2

n 72

n 1.51

__ n .00

n 1.51

lots) _ 19.8

. __ 8.3

__ . 10.3

2.3

__ _ 3.5

2.9

26.1

32.4

_ 14.5

51

31.7

21.4

11.0

-21

20.7

46

4

13.8

61.2

517.7

18.1

15.5

74

1.62

.00

1.62

19.0

7.7

16.8

3.6

1.7

2.9

15.7

36.0

16.0

52

32.7

22.5

12.2 -16

20.5

47

5

17.1

59.1

516.4

17.0

16.5

94

1.38

.00

1.38

18.8

4.9

11.4

2.2

3.5

1.9

23.5

33.8

18.8

62

40.7

30.3

19.9

-10

20.8

42

3

24.0

55.4

518.1

16.8

11.0

62

1.63

.00

1.63

16.8

7.6

10.3

2.7

4.9

1.7

29.9

33.1

9.9

69

46.9

36.2

25.6

2

21.2

45

2

28.4

51.5

519.2

12.9

2.4

47

1.11

.10

1.21

15.3

7.3

14.2

1.4

5.4

4.2

25.1

31.5

11.1

76

58.3

46.0

33.8

12

24.5

38

9

29.9

40.1

522.5

3.5

.1

12

.34

.06

.40

13.5

3.0

10.3

4.8

9.8

5.0

32.7

27.7

6.5

76

65.2

52.6

40.1

22

25.1

42

10

30.9

40.6

526.1

.4

.0

1

.04

1.30

1.34

12.3

3.4

8.0

4.1

15.2

14.5

25.1

26.1

3.4

74

63.9

51.4

38.9

17

25.0

41

8

31.0

41.4

525.6

.2

.0

3

.02

.74

.76

12.2

1.7

7.2

6.1

13.7

11.1

33.9

22.3

4.4

72

58.4

45.7

33.1

10

25.3

49

6

30.0

44.8

524.3

1.2

.0

1

.12

.48

.60

13.0

4.1

5.8

5.4

9.8

13.3

29.1

26.9

5.8

76

50.3

38.4

26.5

-7

23.8

58

6

29.4

45.5

523.1

5.1

.3

12

.48

.04

.52

13.8

5.0

11.8

3.8

10.9

9.1

27.3

25.8

6.6

61

40.6

29.3

18.1

-13

22.5

49

2

23.9

52.5

521.3

11.1

3.4

30

.92

.00

.92

15.8

7.8

13.6

3.0

5.6

6.5

24.2

29.4

9.8

57

34.3

23.5

12.7 -19

21.6

40

3

19.4

55.1

520.1

13.3

5.7

50

.96

.04

1.00

17.9

6.6

12.3

2.4

5.1

7.4

23.4

27.1

15.7

76

46.1

34.8

23.4

-21

22.7

58

1

291.6 peryr

50.7

1523.8

114.4 per yr 14.7

94

10.14 per yr

2.73 per yr

12.87 per yr

15.8

5.8

11.0

3.5

7.5

6.5

26.2

29.6

10.3

72

35.5

27.4

19.7 -35

16.1

44

2

204.5 per yr

55.1

'481.3

164.4 per yr '7.2

73

14.87 per yr

2.11 per yr

16.98 per yr

22.5

12.7

5.6

5.4

5.0

7.9

17.0

39.9

9.8

1 1953-62.

TABLE 2: Types of information obtained at Crooked Creek Laboratory 

and five auxiliary weatherstations during the period June 1966 to 

August 1967

Fie URE 273. North Sage Hen Flat auxiliary weather station and dust trap. Evaporimeter to 

left of pole, thermometer in white container to right of pole, dust trap on top. Rain gage to 

left and rear of stand. View west, showing parts of the upland surface, with the Sierra 

Nevada in distance.

Four-inch-diameter sections of stovepipe, 2 ¥2 feet long 

and sealed at the bottom, were used as rain gages. 

Lightweight oil was added to minimize surface evaporation. Taylor maximum-minimum window thermometers, suspended inside white ^-gallon ice cream 

containers, were used for temperature readings. Relative evaporation rates were obtained with modified 

Piche evaporimeters (Waring and Hermann, 1966). 

Temperature and precipitation readings were taken at 

bimonthly intervals from June 20 through September 

1966, at the end of October 1966, and at monthly intervals from June to August 1967. Evaporation readings 

were obtained only during the summer of 1966. Table 2

Name

Position Maximum- EvapoAbbre- relative to Eleva- minimum ration

viation center of area tion (ft) temperature Precipitation rate

Crooked

North

South

CC

B

C

NSH

SSH

West__ __ __

10,150 Yes

10,200 Yes _ ___

10,440 Yes

10,660 Yes

10,740 No

11,250 No

. . Yes

Yes _

.__ Yes _ _

Yes

Yes

Yes

No.

Yes.

No.

Yes.

Yes.

Yes.

summarizes types of data collected at each weather 

station.

A plot of temperature and evaporation rates for the 

auxiliary weather stations and Crooked Creek is shown 

in figure 274. The Campito and North Sage Hen AWS 

sites show nearly the same maximum and minimum 

temperatures; the Basalt commonly has lower maximums and higher minimums. All Crooked Creek 

temperatures fall below those obtained on the upland 

surface, often by as much as 10-15°F. Evaporation data 

are quite spotty owing to malfunctioning at several 

sites, but the Basalt AWS values tend to be highest, 

followed by North Sage Hen, South Sage Hen, and the 

Patriarch. The comparison suggests a slight trend toward increasing evaporation rates from west to east, 

possibly owing to decreasing elevation. Since temperatures do not appear to increase eastward, the increased 

evaporation may be the result of a lower relative humidity. A comparison of precipitation at the five AWS sites 

and Crooked Creek (fig. 275) indicates highest values at
384 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

>

< 20 

D

c 15 

ID 

Q- 10

1 5

s °,

~ 80'

70

60

50

40

30 

20

10

0

-10

: : :* *

1

: + +x *

* 00 °0 0 I E

° i

+ t ;

- * * ; ! : 1 0 C

* i

i i i i i /, I ,,\

-

-

w

°-

^ -

-

-

°x ;

i- -

-

i

40

7-1-66 8-1 9-1 10-1 

EXPLANATION

11-1 7-1-67 8-1

Crooked Creek Laboratory

North Sage Hen auxiliary weather station

Campito auxiliary weather station

Basalt auxiliary weather station

South Sage Hen auxiliary weather station

Patriarch auxiliary weather station

FIGURE 274. Maximum and minimum temperature and relative evaporation rates at 

Crooked Creek Laboratory and five auxiliary weather stations in the study area.

Crooked Creek, closely followed by the Patriarch AWS. 

All the other sites received much less precipitation and 

tend to follow the order North Sage Hen > Basalt > 

Campito > South Sage Hen. There is a general trend of 

increasing precipitation toward the north, and higher 

values were recorded in the valley of Crooked Creek 

than on the surrounding upland surface, probably because the AWS sites were exposed to high winds which 

would tend to decrease catchment of precipitation and 

to deflate snow accumulations.

Crooked Creek data for wind velocity and direction, 

barometric pressure, and to some extent, relative 

humidity, approximate present-day climatic conditions 

for most of the study area. Absolute precipitation values 

at Crooked Creek are probably much more reliable than 

those obtained at the auxiliary stations, but the fact 

that the latter are much lower should not be dismissed 

altogether, for they suggest that Crooked Creek values 

may be high owing to drifted snow blown from adjacent 

slopes. To obtain representative temperature estimates 

for nearby upland surface areas, Crooked Creek maximum temperatures should be increased by about 10°F 

and minimum temperatures by about 5°F. In the northern part of the study area, precipitation and relative 

humidity are probably somewhat higher and temperatures slightly lower than further south owing primarily 

to differences in elevation. With this exception, present 

climatic gradients in the study area are not marked.

35

30

25

20

15

EXPLANATION

CC = Crooked Creek Laboratory

P = Patriarch auxiliary weather station 

NSH = North Sage Hen auxiliary weather station 

B = Basalt auxiliary weather station 

C = Campito auxiliary weather station 

SSH = South Sage Hen auxiliary weather station

1 =6/2B/66 to 10/29/66

2 =10/29/66 to 6/28/67

3 = 6/28/67 to 7/22/67

4 = 7/22/67 to B/17/67

5 = 6/28/66 to 8/17/67

SSH

SSH

NSH B

RAINFALL SNOW TOTAL PRECIPITATION

FiGVRh 275. Precipitation recorded at Crooked Creek Laboratory and at five auxiliary 

weather stations for the indicated periods.

VEGETATION

The flora of the study area includes the Bristlecone 

Pine Forest and Sagebrush Scrub plant community 

types of Munz and Keck (1959, p. 11-18). Toward lower 

elevations the vegetation passes into Pinyon Juniper 

Woodland, and at higher elevations into Alpine Fell 

Fields. Stands of bristlecone pine (Pinus aristata), 

limber pine (Pinus flexilis), and aspen (Populus tremuloides) make up a discontinuous tree canopy along the
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 385

crest of the range below about 11,500 feet. A continuous 

shrub understory on noncarbonate soils is dominated by 

sagebrush (Artemisia tridentata and A. arbuscula) and 

to a lesser extent by rabbitbrush (Chrysothamnus 

viscidiflorus), mountain mahogany (Cercocarpus 

ledifolius and C. intricatus), creambush (Holodiscus 

microphyllus), mountain misery (Chamaebatiaria millefoliurri), and currant (Ribes velutinwri). Beneath this 

two-story canopy of trees and sagebrush scrub is a 

nearly ubiquitous but sparse cover of grasses and herbaceous perennials, mostly low to the ground and often 

inconspicuous.

Most areas are dry, but moister conditions occur locally along streams and near seeps and springs. Such 

sites are characterized by annual grasses as well as 

Carex spp. (sedges), Cirsium drummondii (thistle), 

Artemisia ludoviciana (sagebrush), Castilleja miniata 

(paintbrush), and several species ofPenstemon (beardtongue), Mimulus (monkey flower), and Oenotkera 

(evening primrose).

Many plant species in the White Mountains are 

partly controlled by substrate in their distribution 

(Marchand, 1973). Edaphic restriction is evident in all 

vegetational strata, from bristlecone and limber pine to 

the smallest perennials. The principal botanical discontinuities occur across carbonate-noncarbonate boundaries (fig. 276): dolomites and limestones support similar vegetation as do, with a few notable exceptions, 

noncarbonate lithologies. Vegetation on sandstone and 

shale, granitic bodies, and basalt shows subtle differences which are sufficiently consistent to permit 

identification of three noncarbonate plant communities, each characteristic of a given bedrock type.

FIGURE 276. Vegetational contrast between dolomite outcrops and colluvium (foreground 

and right rear) and sandstone colluvium (darker colored). Sandstone is covered by sagebrush and numerous other perennials, dolomite by certain small perennial herbs and 

bristlecone pine.

GEOLOGY

A complex mixture of sedimentary, igneous, and 

metamorphic rocks constitute the bedrock of the southern White Mountains (fig. 277). The oldest strata in the 

region are a slightly metamorphosed Precambrian to 

Early Cambrian succession of sandstones, shales, 

limestones, and dolomites. The Precambrian Wyman 

Formation, consisting primarily of sandstone and shale 

with minor but conspicuous lenses of white limestone, is 

the oldest of this group. Overlying the Wyman is the 

Reed Dolomite, a massive and very pure carbonate rock. 

The Deep Spring Formation, composed of alternating 

members of carbonate rocks (both limestone and dolomite) and clastic sediments (quartzitic sandstone and 

shale) overlies the Reed. The next youngest formation is 

the Campito, consisting of a lower quartzose sandstone 

member, the Andrews Mountain, and an upper shale 

member, the Montenegro. The Precambrian-Cambrian 

boundary, coinciding with the base of the Fallotaspis 

Olenellid biozone (Taylor, 1966), occurs within the 

upper part of the Andrews Mountain Member. The 

youngest stratigraphic unit of the group is the Poleta 

Formation, a somewhat shaly carbonate.

This succession was tilted toward the west and then 

intruded by the adamellites of Sage Hen Flat (130-138 

m.y. (million years)) and Cottonwood area (151-170 

m.y.) during the late Mesozoic (McKee and Nash, 1967, 

p. 672). Early to middle Tertiary erosion resulted in the 

beveling of a surface of low relief across the region (fig. 

278), although monadnocks of Reed Dolomite and Andrews Mountain sandstone stood well above the erosion 

surface during its development. Parts of this surface 

were subsequently covered by thin local sediment and 

extensive basaltic flows (figs. 272, 279), K/Ar dated by 

Dalrymple (1963) at 10.8 m.y.

In terms of late Cenozoic structure, the White Mountains are an eastward-tilted horst which exhibits relatively greater uplift on the west, where a steeply dipping fault zone bounding the range has undergone as 

much as 10,000 feet of normal displacement. The east 

margin is also faulted along the northwest side of Deep 

Springs Valley, but individual displacements here are 

about 1,000 feet or less. The basalts and underlying 

erosion surface are tilted and faulted up from 6,000 feet 

at the northeast end of Deep Springs Valley to 10,800 

feet at Bucks Peak, showing that tectonic activity occurred later than 10.8 m.y. ago. Bateman and Wahrhaftig (1966) presented convincing evidence for regional 

uplift of east-central California and western Nevada 

between about 9 and 3.5 m.y. before present and formation of Owens Valley and other collapse structures 

along the axis of uplift during a period of downfaulting 

beginning about 2.5 m.y. ago. The "Waucoba Lake
386 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Campito Formation, Andrews 

Mountain Member

Deep Spring Formation

cn

Reed Dolomite

 °f^\?o H*'V°- -V.° Cf^\! °0 ;0/«V -' '.- '?"»*>;" '' : .-;. :'' -v.'^v- -, -. V ««^V:'°%.^ »<°«XVVV\ °A;^- ' ----- %c-V-'-;---.--. >-.-^ *^A

:^\'»-?^^V.0 \\^0^0-°-%v^'V; -'-V-f- ----- ' <' : ? '. ':" ; ;v-vst *',

:-^v^kv^ ^^>!^f° I?^*^-!^^-^":-""?^ ;-^::^V^'

FIGURE 277. General geology and sample locations in the study area.

Beds," exposed on the upthrown side of the frontal fault 

east of Big Pine, possess a predominantly Sierran 

mineralogy and apparently represent deposition in an 

early Pleistocene pluvial lake prior to the downfaulting 

of Owens Valley. The uppermost of several rhyolitic 

tuffs in the lakebeds has given a K/Ar age of 2.3 m.y. 

(Hay, 1966, p. 20). Coarse clastic debris from the White 

Mountains overlies and intertongues with the upper 

part of the lakebeds, which now dip westward at 5-7°, 

indicating some uplift of the range or downwarping of 

Owens Valley during the latter part of lakebed deposition, about 2.3 m.y. ago. The range-front faulting may 

have begun at this time, but cannot have preceded the 

lakebed deposition. Regional arching therefore appears 

to have preceded faulting by at least 1 million years in

this area, although some uplift in the White Mountains 

may have occurred as recently as 2.3 m.y. before present.

Pleistocene glaciation along the eastern slope of the 

White Mountains north of the study area has incised 

cirques and U-shaped valleys into the upland surface 

and has left morainal and outwash deposits along the 

valley walls and floors. According to D. R. Powell (1967, 

oral commun.), recognizable glacial advances in the 

White Mountains appear to correlate with those of the 

eastern Sierra Nevada. Quaternary alluvium and terrace deposits are present along most of the major 

streams draining the range, especially on the east flank 

where gradients are gentler. Interbedded with terrace 

alluvium along Crooked Creek and its tributaries is a
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 387

FIGURE 278. View north across Sage Hen Flat, showing degraded White Mountain erosion 

surface and outcrop areas of adamellite of Sage Hen Flat (light colored, foreground and 

middle distance). Reed Dolomite (white, tree covered), and Andrews Mountain sandstone 

(dark, left distance).

FIGURE 279. View east from Sage Hen Flat, showing resistant basalt capping less resistant 

metasediments and granitic intrusive rock.

FIGURE 280. Exposures of reworked rhyolitic ash interbedded with terrace alluvium along 

Crooked Creek. White layers are largely composed of pumiceous material.

white, reworked pumiceous ash (fig. 280), rhyolitic in 

composition and as much as 0.6 feet thick. Although 

glass shards and rhyolitic mineral fragments occur in 

soils throughout the area, no primary deposits have 

been seen. On the basis of major elements, trace elements, refractive indices, mineralogy, and physical appearance, the ash has been correlated with a source at 

Mono Craters (probable) or Mono Glass Mountain (possible), both located on the eastern Sierra Nevada slope 

south of Mono Lake (Marchand, 1968, 1970).

Those parts of the White Mountain erosion surface 

which have not been totally destroyed have been lowered several hundred feet to the level of Sage Hen Flat 

(fig. 278), Reed Flat (fig. 272), or similar areas of subdued, rolling topography by late Tertiary or Quaternary 

erosion. Frost heaving, solifluction (including altiplanation), nivation, and other periglacial phenomena continue to affect the range, becoming increasingly important toward higher elevations. Rillwash channels as 

much as 2 inches deep and debris accumulations behind 

trees, fallen limbs, bushes, and large boulders testify to 

the effectiveness of slope runoff processes, particularly 

on the relatively bare surfaces beneath bristlecone pine 

forest. Talus cones and stone stripes are frequent, particularly in the Campito Formation and other sandstones or shales. Although eastward draining canyons 

are gradually eroding headward into degraded remnants of the erosion surface, fairly extensive parts of the 

lowered surface are still relatively undissected and
388 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

often serve as a local or temporary base level for periglacial processes and slopewash. The effect of these circumstances is the accumulation of colluvium (consisting of weathered and unweathered rock, mineral, and 

organic material) on gentle slopes and in topographic 

lows on these surfaces.

To put present climatic data into perspective, it is 

necessary to consider the regional climatic and tectonic 

changes that have occurred in the area during the late 

Cenozoic. Any attempt at backward extrapolation of 

climatic conditions is extremely hazardous, especially 

in areas such as this where faulting and uplift have 

complicated an already complex series of fluctuations, 

but a few conclusions appear to be valid: (1) Cold, dry, 

climatic conditions such as those which currently 

characterize the area, and the more severe climates of 

glacial periods, are not conducive to rapid soil formation 

(for example, cf. Morrison, 1964, p. 114); (2) the White 

Mountains area was at a lower and presumably warmer 

elevation and probably did not lie in the Sierran rain 

shadow prior to regional uparching, between 9 and 3.5 

m.y. ago; (3) considering the total duration of warm, 

wet, or warm and wet intervals which promote rapid 

weathering, it would appear likely that most of the total 

amount of soil formed on the White Mountain surface 

occurred prior to or during the regional uplift, perhaps 

augmented during extended interglacial periods. The 

immaturity of present soils indicates that most of the 

weathered debris has been stripped by erosion, but the 

extreme weathering of some soil grains may date from 

an earlier period of soil formation.

CHEMICAL WEATHERING AND 

SOIL DEVELOPMENT

Chemical weathering is so closely interrelated with 

physical weathering that it is sometimes difficult to 

distinguish their separate effects. Taken together these 

two processes are responsible, along with various organic effects, for the development of soil. Because of the 

close ties between physical and chemical processes in 

the evolution of soils, both aspects are considered here, 

although primary emphasis is placed on chemical 

weathering.

METHOD OF APPROACH

The immature soils in this area formed on four widespread parent materials. Because spring waters closely 

related to sandstone and basalt were not available and 

because changes in the liquid phase are important considerations in this study, detailed discussion is restricted to the Reed Dolomite and adamellite of Sage 

Hen Flat, two commonly recurring lithologies for which 

closely related spring waters could be obtained. For the 

dolomite and adamellite the sequence and degree of 

physical weathering is evaluated, and problems of soil

contamination are discussed. Chemical weathering is 

approached from the perspectives of chemical and 

mineralogical changes in dolomite and adamellite and 

of chemical changes in liquid phases associated with 

each lithology.

FIELD METHODS

After the geologic and soil mapping of the area (figs. 

277, 281-284), 84 sample sites, about 20 to each lithology, were chosen at relatively even spacings on Reed 

Dolomite, adamellite of Sage Hen Flat, basalt, and 

sandstone of the Andrews Mountain Member of the 

Campito Formation. (See fig. 277 for site locations.) 

Topographic highs were selected for sample locations to 

minimize contamination by slopewash, mass wasting, 

and aeolian processes. Soil samples encompassing the 

entire profile above the C horizon were collected at 

every site and fresh bedrock samples were also obtained 

on dolomite and adamellite sites. Eight surface soil pH 

measurements (determined using pHydrion paper and 

a Truog indicator kit) were made at each site within a 

7-foot radius of the soil pit. The dimensions of the pit 

were measured as closely as possible, its volume was 

calculated, and the soil samples were weighed (air dry) 

after collection to obtain bulk density figures for the 

whole soil. Representative profiles were described, and 

field impregnations were made at several sites for 

dolomite, adamellite, and basalt soils. Over a 14-month 

period from June 1966 to August 1967, samples of rain, 

snow, and of spring waters related to the adamellite and 

dolomite were collected.

LABORATORY METHODS

Samples of both dolomite and adamellite were randomly selected for detailed chemical and mineralogical 

study in the laboratory. Minerals were identified 

primarily by petrographic microscope, aided by 

reflecting microscope for opaque minerals. Compositions of glass fragments were determined by immersion 

oils, universal stage, and electron microprobe. The 

microprobe was also used to assess chemical alteration 

within weathered minerals. Estimates of major mineral 

percentages in fresh adamellite were determined from 

point counts of stained thin sections. Percentages of 

minor mineral phases in adamellite, all dolomite constituents, and all minerals in sand fractions of soils 

were obtained from line counts of grain mounts, after 

two heavy-liquid separations. Silt- and clay-sized fractions were analyzed qualitatively and quantitatively by 

X-ray diffraction. Layer silicates were identified following the methods of Warshaw and Roy (1961). Contaminative rhyolitic glass in the silt range of soils was 

estimated visually in oil immersion mounts. X-ray 

fluorescence was employed in the chemical analysis of 

bedrock and soil samples. Standard sieve and pipette 

techniques were utilized in size analyses of 26 dolomite
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 389

and adamellite soils. Other analytical methods used are 

discussed at appropriate places in the report. For a more 

detailed account of procedures, precision, reproducibility, and comparisons of methods, the reader is referred 

to the section "Supplemental Information."

Table 3 summarizes the estimated precision of measurement for some of the analyzed quantities discussed 

in the text. All percentages in the text, tables, and 

figures are weight percent, unless otherwise noted.

TABLE 3. Estimated precision of measurement for some analytical 

quantities discussed in this paper

[See also "Supplemental Information"]

Analytical method

Estimated range of precision 

(percent of given value)

X-ray fluorescence ____________

Grain counting:

Major minerals____________

Minor minerals __________

X-ray diffraction (silts) ________

Size distribution:

Sieve range ______________

Pipette range (silt and clay)

±6

±5

±10-15

±15

±2 

±10

Plant ash analyses ______________ ±20 (usually < 10)

Analyses of water-saturation extracts __ ±25

NF^Ac extract analyses___________ ±20

DESCRIPTION OF SOILS

CLARIFICATION OF TERMS

In the White Mountains, as in other areas of high 

relief, absolute distinctions between residual soil and 

weathered colluvium are essentially arbitrary. Periglacial processes, as well as mass wasting, slopewash, and 

aeolian transport, are actively moving loose material 

into topographic lows. Many definitions of soil imply 

formation by in situ weathering alone (for example, cf. 

Brewer, 1964, p. 7-8), apart from the effects of erosion 

and deposition. For purposes of this discussion, the term 

"soil" will be expanded from this usage to include some 

colluvial and windblown material. In the present context, "soil" encompasses all weathered or slightly 

weathered surficial debris other than talus, stone stripe 

boulders, slopewash fans, alluvium, and sand dunes and 

necessarily includes debris that has undergone some 

slope transport, albeit of relatively short distance in 

many cases.

The White Mountains soils are almost exclusively 

poorly developed lithosols having general A1;l /A12 /C/R 

profiles less than 13 inches deep. Color, structural, or 

textural B horizons are faintly visible in a few profiles, 

but such occurrences are rare. Calcium carbonate crusts 

can be found on all lithologies, but are abundant only on 

dolomite soils. An irregular surface layer of relatively 

large fragments (An horizon), brought to the surface by 

frost heaving, is a common feature of most profiles, 

independent of parent material. Beneath this stratum 

is a layer of finer grained weathered material (A12 horizon), usually overlying large partly weathered fragments in a matrix of silt and sand (C). Fresh bedrock (R) 

is generally encountered within 1 or 2 feet of the top of 

theC.

Planetable maps of topography and maximum soil 

depth for representative areas within dolomite, adamellite, and basalt terranes are shown in figures 281-284. 

Maximum soil depth was taken as the greatest penetration of a 1-inch-diameter soil auger in repeated borings 

at a given location. These depths correspond to the approximate top of fresh bedrock, except in deep profiles 

where lateral friction on the auger made further penetration impossible. The map isochores indicate a general thinning over topographic highs and steep slopes 

and thickening in local depressions, especially on Sage 

Hen Flat. Soil thickness appears to be somewhat erratic 

on the basalt and dolomite. Two dolomite areas at different elevations show no appreciable differences in soil 

depth. In the Patriarch area, the thickest soils occur in 

minor interfluves, and the thinnest are found in the 

intermittent stream channels, suggesting that the latter are presently sites of erosion or slow weathering. 

This relation contrasts with that of Sage Hen Flat, 

where surficial material is thickest along topographic 

lows.

The application of lithologic names to soil units (that 

is, Reed Dolomite soil) represent informal usage only;

Maximum soil depth (feet) 

Interval 0.2 feet

Relative topography; number 

is feet above arbitrary datum. 

Interval 5 feet

Planetable site

100 FEET

FIGURE 281. Depth of soil and colluvium at planetable map site R-l, Reed Dolomite, 10,600

feet
390 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Maximum soil depth (feet) 

Interval 0.2 feet

Relative topography; number 

is feet above arbitrary datum. 

Interval 5 feet

Planetable site

+ 2

Soil descriptions and impregnations

FIGURE 282. Depth of soil and colluvium at planetable map site R-2, Reed Dolomite, 11,200

feet.

Maximum soil depth (feet) 

Interval 0.4 feet

Relative topography; number 

is feet above arbitrary datum. 

Interval 5 feet

no attempt has been made to formally designate or map 

soil series in this area.

Average soil profile thickness to Reed Dolomite bedrock, about 7 inches at sampled sites, is slightly greater 

than for other soil groups. White calcium carbonate 

surface crusts, usually discontinuous and less than 

one-half inch thick, are one of the most conspicuous 

features of the Reed profiles. Calcium carbonate is absent in lower parts of the A horizon, but occurs at the 

A-C interface and on nearly all rock fragments within 

the profile. Local O horizons, consisting of undecomposed and partially humified plant litter together with a 

few mineral grains occur sporadically beneath trees. 

Where O horizons are present, carbonate crusts are 

absent. Rock fragments concentrated near the surface 

in AH horizons (fig. 285) usually appear quite fresh, 

except for minor solution pitting. Rock in the C horizon, 

however, is often so thoroughly decomposed that it is 

easily broken with a trowel. A12 horizons are occasionally quite red owing to oxidation of Fe-bearing minerals. Subangular blocky peds are common here, but 

structure in other horizons is generally single grained 

or massive. The pH may be below 7.0 in or near O 

horizons, but the normal range is between 7.5 and 8.2,

Planetable site

Soil descriptions and impregnations

FIGURE 283 Depth of soil and colluvium at planetable map site S-l, adamellite of Sage Hen

Flat.

appreciably higher than in noncarbonate soils. The pH 

tends to be high at the surface, lower in the A horizon, 

and high again near and within the C horizon, causing 

precipitation of calcium carbonate in localized areas jf 

high pH within the soils.

ADAMELLITE SOILS OF SAGE HEN FLAT

The soils on adamellite of Sage Hen Flat are characterized by a general lack of large rock fragments above 

the C horizon. The surface horizon is commonly a grus, 

consisting of granules and coarse sand, and is usually 

less than 1 inch thick (fig. 286). Calcium carbonate 

crusts, although occasionally present, are not common 

and may result from solution of inblown carbonate 

grains. O horizons occur in forested areas. Sandy loam 

A12 horizons are infrequently underlain by weak color, 

structural, or textural B horizons, in which iron oxidation, subangular blocky structure, and very weak clay
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 391

EXPLANATION

Relative 

is feet 

Interv;

FIGURE 284. Depth of soil and colluvium at planetable map site B-l, on basalt.

FIGURE 285. Reed Dolomite soil pit showing accumulation oflarge fragments (Alt horizon) 

overlying finer grained A12 horizon.

films may be visible. The transition to the C horizon is 

often abrupt on topographic highs, but gradual in areas 

where the parent material is largely colluvial. Fragments in the C horizon may bear only thin weathering

FIGURE 286. Soil pit in adamellite of Sage Hen Flat. Thin grus layer (An horizon) overlies 

A12 horizon, which tends toward a color and textural B at some sites. Lighter colored C 

horizon is transitional downward into unweathered colluvium (not shown).

rinds or may be quite thoroughly decomposed. Depth to 

bedrock averages about 6 inches on topographic highs.

BASALT SOILS

Basalt soil profiles average about 6 inches in depth 

and are characterized by good crumb structure in most 

A horizons and by a sharp A-C contact. Calcium 

carbonate crusts are rare, the surface layer generally 

consisting of coarse fragments or basaltic grus. Beneath 

this pavement is a vesicular gravelly loam to clay loam 

A12 horizon, as much as 4 inches thick, with subangular 

blocky peds. The lower part of the A horizon is often 

oxidized, but rarely is there other evidence of an incipient B horizon. Surface cracking and the degree of aggregation suggest higher clay contents than in other 

soils. Roots are uncommon, and O horizons are never 

present. The pH does not vary consistently with depth 

in the profiles.

ANDREWS MOUNTAIN SANDSTONE SOILS

Soils formed on the Andrews Mountain sandstones
392 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

and shales show a striking bimodal size distribution: 

Large rock fragments are concentrated at the surface 

near and within the C horizon, while sand, silt, and 

minor clay occur primarily in the Ai2 horizon. Calcium 

carbonate crusts are present locally but are not common. The A12 horizon is usually single grained or massive, although aggregation into crumbs may occur. The 

C horizon consists of colluvium or slightly weathered 

bedrock. As in other noncarbonate soils, the pH is generally 7.0 or slightly below and does not change systematically within the profile.

SOIL CONTAMINATION

Mineralogical analyses of five soils derived from the 

Reed Dolomite reveal from 3 to 73 percent of material, 

primarily volcanic glass, quartz, feldspars, biotite, and 

hornblende, that cannot be accounted for by weathering 

changes. The principal sources of this contamination 

are the pumiceous ash from the Mono Craters or Mono 

Glass Mountain (as much as 30 percent) and local 

windblown fragments (as much as 50 percent). The extent, nature, and implications of the soil contaminants 

were discussed elsewhere (Marchand, 1970). Their 

abundance necessitates considerable correction of soil 

data at most sites, as explained under "Chemical 

Weathering," and renders many soil samples uninterpretable in terms of weathering.

PHYSICAL WEATHERING

REED DOLOMITE

The Reed Dolomite is strongly jointed in one direction. Cross jointing is common, breaking the crystalline 

rock into angular fragments of about 3 feet to less than 

one-half inch in maximum dimension.

Bedrock grain size varies considerably depending on 

degree of recrystallization due to thermal metamorphism. Micrometer eyepiece examination of 16 bedrock 

samples indicate a mean diameter range of from 0.002 

to 2 mm. Dolomite displaying spheroidal weathering 

has a bedrock grain size range from 0.125 to 2 mm, but 

angular dolomite is much finer grained, ranging from 

0.002 to 0.125 mm.

Cumulative grain size frequency curves for 10 dolomite soil samples (fig. 287) show strong bimodal distributions indicative of immature weathering. The two 

modes are in fragments above 8 mm (jointed blocks) and 

in finer materials derived from the large blocks. For 

comparison, the range of bedrock grain size has been 

superimposed on the diagram. Triangular plots of 

dolomite, adamellite, and Andrews Mountain sandstone soils in terms of gravel, sand, and silt and clay, 

and of sand, silt, and clay are shown in figures 288 and 

289, respectively. Gravel percentages vary greatly 

owing to extremely large fragments whose presence or FK-.I-RI 2sa Gravei-sand-siit and day distribution for soil above the c horizon.

From spheroidally 

weathered areas

Bedrock ranges: 

Spheroidally Angularly

0.0036 mm

GRAIN SIZE (0)

FIGURE 287. Cumulative grain size frequency curves for dolomite soils and comparison with 

ranges in bedrock grain size based on samples from both spheroidally and angularly 

weathered sites.

GRAVEL EXPLANATION 

Reed Dolomite soil 

Adamellite soil 

Andrews Mountain

sandstone soil

80

60

SAND

40

20

SILT AND CLAY
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 393

CLAY

EXPLANATION

Reed Dolomite soil 

Adamellite soil 

Andrews Mountain 

sandstone soil

SAND SILT

FIGURE 289. Sand-silt-clay distribution for soil above the C horizon.

absence strongly influences the results. Relative 

amounts of sand, silt, and clay are more consistent.

The pattern of physical rock weathering after jointing 

and surface exposure appears to be a function of the 

earlier thermal history of the rock. Carbonates (both 

limestones and dolomites) adjacent to the Sage Hen and 

Cottonwood plutons tend to weather relatively rapidly 

to produce spheroidal boulders, whereas slower weathering of angular blocks characterizes carbonate terrane 

away from plutonic contacts. Most dolomite soils show 

maximums in the 2-4 phi interval, but several samples 

derived from thermally metamorphosed and spheroidally weathered dolomite have modes in the 1-2 phi 

range. Dolomite joint blocks have thus undergone two 

types of breakdown: (1) Fine-grained dolomite blocks 

have remained angular, and slow physical disintegration has produced smaller polycrystalline aggregates; 

(2) intergranular stresses within coarse-grained recrystallized dolomite developed during cooling from 

metamorphic conditions to subaerial temperatures 

have caused breakdown to single-crystal grains. This 

second weathering pattern was first noted and explained by LaMarche (1967), who contended that 

spheroidal forms are created by preferential attack at 

corners and edges of the more susceptible rock and are 

maintained by the greater porosity of the weathering 

block exterior. The author's observations corroborate 

those of LaMarche except that unrecrystallized dolomite commonly weathers to polycrystalline rather than 

monocrystalline grains as suggested by LaMarche, at 

least in the initial phase of physical weathering. Cleavages apparently afford an easier avenue of parting than 

the tightly held grain boundaries, except where contraction has created intergranular weaknesses.

ADAMELLITE OF SAGE HEN FLAT

Joints spaced as closely as 2-6 inches, but more commonly several feet apart, occur throughout the Sage 

Hen Flat pluton and tend to fall into two categories: A 

principal group trending north-northeast and dipping 

steeply to the southeast and a secondary group striking 

northwest and inclined to both northeast and southwest. Joint blocks are larger than in the dolomites and 

consequently have a lesser effect on weathering processes. Some joint openings and adjacent wallrocks have 

been silicified, sericitized, and tightly cemented with 

iron oxides. Such alteration is almost certainly deuteric 

or hydrothermal, as large crystals of mica have grown 

within feldspars adjacent to joint planes, in contrast 

with the fine-grained feldspar weathering products observed in soil thin sections. The altered joint planes and 

adjacent rock weather in positive relief with respect to 

adjacent adamellite (fig. 290), as do fine-grained mafic 

inclusions and aplitic dikes.

The medium-grained hypidiomorphic-granular texture of the adamellite locally tends toward porphyritic, 

but microscopic examination of 17 thin sections indicates that mean grain size never exceeds 4 mm. Average 

grain diameters commonly range from 0.5 to 3.5 phi.

In figure 291, cumulative grain size frequency curves 

for 10 adamellite soil samples and two grus samples are 

shown, along with the superimposed average and extreme ranges of bedrock grain size. With few exceptions, 

the adamellite soils are unimodal, the maximum frequency occurring between 2 and 9 phi in most samples. 

This mode falls within the mean bedrock range, sugFIGURE 290. Weathered adamellite outcrop on Sage Hen Flat. Note relative resistance of 

altered joint planes. Pencil gives scale.
EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

MECHANISMS OF DISINTEGRATION

Of the many mechanisms suggested for physical 

weathering and exfoliation, repetitive freezing of interstitial water seems the most applicable to relatively 

cold regions such as the White Mountains. At Crooked 

Creek Laboratory, temperatures descend below freezing on an average of about 220 days per year, and most 

of the precipitation occurs during the winter.

A striking feature of physical disintegration in the 

study area is that the same process applied to several 

lithologies has resulted in differing soil grain size distributions. This observation and the similarity of grus 

development from granitic rock here with that in much 

wetter and warmer areas suggest that rates and products of physical weathering may be as much a function 

of inherent lithologic properties as of climatic conditions. For frost riving to be effective, water must be able 

to penetrate the rock. The fact that coarse-grained 

lithologies weather more rapidly than fine-grained 

rocks of the same composition lends credence to 

LaMarche's (1967) hypothesis that contraction of large 

mineral grains during cooling from elevated temperatures may result in weakened intergranular bonds, affording access to water during weathering. Grain size 

may thus be one factor causing plutonic rocks to 

weather more rapidly than basalt: A larger grain will 

contract more than will a smaller grain having cooled 

the same amount, creating wider intergranular spaces 

or, if no separation occurs, greater intergranular tensional stresses. Fissility, grain adhesion and cohesion, 

and jointing may also be important factors in determining degree of water penetration.

It is not the author's intent to imply that the contraction mechanism is the only likely cause of grus formation. Wahrhaftig (1965, p. 1178-1179) suggested that 

alteration of biotite to swelling clays may aid in splitting apart intrusive rock into granular fragments. Evidence presented in the following pages indicates that 

expandable clays are not an important biotite weathering product in this area, but Helley (1966) showed that 

biotite can swell without being chemically altered. The 

absence of biotite or similar alterable minerals in the 

dolomite, however, necessitates an explanation other 

than presence of expandable minerals in this case.

An interesting aspect of erosion in the White Mountains is the striking correlation between erosional resistances and the manner of physical weathering in various lithologies. Fine-grained carbonate, quartzose 

sandstone, basalt, and aplitic dikes and mafic inclusions 

within the plutons are relatively resistant to erosion. 

These lithologies tend to produce immature soils having 

bimodal size distributions, large fragments representing one of the modes. Physical breakdown of such mat0.0039mm

GRAIN SIZE «D)

FIGURE 291. Cumulative grain size frequency curves for adamellite soils and comparison 

with ranges of bedrock grain size.

gesting a tendency toward production of single-crystal 

grains by physical weathering. Two grus samples, however, collected beneath exfoliating boulders, show 

modes of-1-0 phi. This material is commonly composed 

of polycrystalline aggregates and occasional large 

grains.

On textural triangular diagrams (figs. 288, 289), 

adamellite soils of Sage Hen Flat plot closer to the sand 

component and farther from the gravel and silt components than do the Reed soils. Large joint blocks are rare 

in the adamellite soils, unlike the dolomite soils. Siltsized grains are not common in fresh adamellite and 

have not been produced to any notable degree by weathering.

A two-stage process of physical weathering is suggested by the data. An initial breakdown into polycrystalline grus, occurring at the weathering surface of rock 

masses, is followed by a size reduction to monomineralic 

grains within the soil profile.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 395

erial into fine particles is obviously very slow and the 

larger blocks are not easily eroded. Recrystallized carbonates, plutonic rock, and shales are much less resistant to physical weathering. These lithologies tend to 

yield submature soils lacking strong bimodal size distributions and containing sand-, silt-, and clay-sized 

particles which can be removed by rillwash and sheetwash. Thus erosion is faster in areas underlain by 

coarse-grained or fissile rock types (Marchand, 1971).

CHEMICAL WEATHERING

CHANGES IN THE SOLID PHASES

MINERALOGICAL CHANGES

REED DOLOMITE

The Reed Dolomite is close to a pure carbonate, containing less than 0.5 percent of minerals other than 

dolomite (table 4). Talc comprises as much as 0.46 percent, but is generally less than 0.1 percent. Ilmenite, 

quartz, K-feldspar, plagioclase, apatite, epidote, and 

garnet are often present in trace amounts, and tremolite occurs in two of the five samples studied quantitatively. Although never observed in thin sections or oil 

immersion mounts, a few grains of biotite, hornblende, 

and magnetite were found in several grain mounts, 

possibly as a result of sieve contamination. Traces of 

chlorite and sericite were identified by X-ray diffraction 

of dolomite residues.

TABLE 4. Mineral weight percentages in five Reed Dolomite bedrock 

samples, based on line counts of grain mounts

47 65 127

Dolomite

Talc . _ _ ..

Ilmenite

Biotite

Hornblende

Garnet

Chlorite

99.51

.46

. _ __ .0496

. - .01

.0012

.0002

. _ .0004

.0007

.0003

99.68

.090

.0214

Trace

.0001

.20

.005

.0003

.0058

.0001

.0002

99.97

.0336

.0005

.0143

.0119

.001

.004

.0003

.0005

.0002

.0001

.0001

99.96

.0067

.0010

.0117

.0008

.0013

.0013

.0004

.0004

.0004

.0009

.0014

99.93

.065

.006

.001

.00003

.001

.00012

.00012

Oil immersion and grain mounts of 3-8 phi (125-4 

size fractions of five dolomite soils were examined 

for degree of etching or alteration of primary noncontaminative grains. Dolomite is strongly etched in all 

samples and in all size fractions (fig. 292), although 

effects are increasingly evident in finer particles. Tremolite is consistently etched, especially at the grain 

terminations, its degree of weathering being generally 

comparable to or slightly less than that of hornblende in 

adamellite soils. The weathering of talc is variable: In 

some samples it appears to be quite fresh, but in others 

has produced extremely irregular grain boundaries (fig. 

293). K-feldspar, plagioclase, and biotite show minor

0.1mm I

0.1mm

FIGLIRL 292. Dolomite. A, Fresh, crushed bedrock (#47). Plane light. B, Etched, embayed, 

altered soil grain (#68 soil, fine sand). Plane light. Note tendency of etching to follow 

cleavage directions.

weathering alteration. Apatite grains are often 

rounded, showing effects of some solution. Quartz and 

ilmenite show little or no alteration, with the exception 

of very minor oxidation around the edges of a few ilmenite fragments. A general four-category weathering sequence, based on the preceding observations, is shown 

in figure 294. Attempts to quantify the sequence 

through grain counts proved unsuccessful owing to the 

abundance of contaminants.
396 . EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Quartz, ilmenite > apatite> K-feldspar, plagioclase, biotite, talc> tremolite, epidote » dolomite

FIGURE 294. Mineral weathering sequence in Reed Dolomite soils, in order of decreasing 

resistance. Based on visual comparison of bedrock and noncontaminative soil grains. 

Vertical lines separate major divisions of resistance.

ft

Fie; VRI 293. Talc. A. Fresh crushed bedrock talc (#47). Plane light. B, Soil talc grains (#47 

soil, crushed, 50-230 mesh). Grains to upper left are not strongly etched, but lower right 

grain shows large embayment. Plane light.

The only mineral that is definitely authigenic in Reed 

soils is calcite, which appears in both silt and clay fractions of about half of the analyzed samples. Several soil 

samples contain 7 A, 10 A, and 14 A layer silicates in 

both silt and clay fractions. These clay minerals are not

believed to be authigenic; they possibly represent the 

chlorite and sericite originally present in the dolomite, 

plus aeolian additions from the surrounding terrain.

ADAMELLITE OF SAGE HEN FLAT

The mineralogy of the Sage Hen Flat pluton is typical 

of an adamellite. Quartz, microcline, and plagioclase 

make up more than 90 percent of the rock; biotite ranges 

from 3 to 7 percent; hornblende, muscovite, chlorite, 

epidote, sphene, ilmenite, and magnetite account for as 

much as 4 percent of the total; and allanite, zircon, 

apatite, and tourmaline are commonly present in trace 

amounts. A few pyrite grains were noted under the 

reflecting microscope.2 Mineral percentages in five 

adamellite bedrock samples are given in table 5, and 

chemical compositions of principal minerals in the pluton are given in table 6.

Minerals in the silt and fine-sand fractions of Sage 

Hen soils and in soil thin sections were examined for 

size reduction and weathering modifications of margins, as compared with fresh bedrock grains. Plagioclase of composition An25_3o in the cores of zoned crystals is generally the most strongly weathered mineral 

in adamellite soils (fig. 295); fine-grained alteration 

products, chiefly kaolinite, sometimes make up much of 

the original plagioclase. Hornblende grains frequently 

possess no unmodified boundaries, the terminations

TABLE 5. Mineral weight percentages in five adamellite bedrock samples from Sage Hen Flat based on point counts of stained thin 

sections

86 94 97 105

Biotite

Chlorite _ _

Epidote _ _

Allanite . .

29.2

25.8

37.9

_ ___ 6.7

.. __ .022

. _ - .05

.13

.057

___ _ .0004

.0081

.0036

_ . .0016

. __ .015

30.2

19.1

41.0

5.4

.24

.3

.75

.088

1.10

.008

.60

1.27

.025

23.9

25.4

38.8

5.5

.42

2.1

.61

.76

.18

.32

.0095

1.98

.01

.03

30.8

25.7

33.5

3.2

.102

1.2

.008

2.8

Trace(?)

.0003

.105

2.65

.003

39.7

23.4

26.9

7.1

.32

1.62

.39

.018

.0854

.0037

.42

Trace.

.025

2Sulfides are localized along joints and near the margin of the pluton and are consequently 

not common in the samples examined. All nonmagnetic opaque minerals are therefore 

combined under the term "ilmenite" for the purposes of this discussion. The weathering of 

local sulfide concentrations, however, is of definite importance, as evidenced by significant 

sulfate values in spring waters draining the pluton.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 397

TABLE 6. Chemical compositions of 10 major minerals in the adamellite of Sage Hen Flat

[Methods of determination as indicated. All Fe assumed to be in ferric state]

Electron microprobe (percent) U

Stage Oil immersion

Annite 

An Ab Or (Febiotite) Phlogopite K Ca Mg Fe Al Ti An

Indices of refraction

NX' Ny Nz'

Plagioclase: 

Maxh 

Minin 

Mean

Microcline: 

Maxii 

Minin 

Mean

Biotite: 

Maxii 

Minir 

Mean

Chlorite:

Maximum 

Minimum 

Mean __

Hornblende: 

Maximum 

Minimum 

Mean __

Epidote:

Maximum 

Minimum 

Mean __

Allanite:

Maximum 

Minimum 

Mean __

Sphene:

Maximum 

Minimum 

Mean __

Magnetite: 

Maximum 

Minimum 

Mean __

Ilmenite:

Maximum 

Minimum 

Mean __

30.5

.2

.0

.0

88.2

12.7

2.4

7.1

2.1

95.8 _ .

85.4 _

93.7

(Ba-0.0) _

(Ba-0.0) _

48.8

40.6

43.4

44.4

31.5

38.1

7.7

7.0

7.5 (Ba-0.79) _.

.3

.3

1

.2 _

29

15

- 1.522 1.525

1.633

Trace 10.0 19.8

.0 8.9 18.2

.0 9.5 18.6 1.624.

7.6 8.5 10.4

7.0 7.3 9.2

7.3 7.7 9.9

17.2 .0

16.0 .0

16.5 .0

9.9 

8.5 

9.2 1.756 1.773

9.4 ____ 12.7 9.3

7.1 ___. 10.9 7.0

8.0 ____ 11.5 8.2 < 1.775 1.772 >1.775

24.5 .0 1.5 0.8 19.8

21.7 .0 1.1 0.6 18.7

23.3 .0 1.2 0.7 19.1 1.898 1.941 >2.00

.08 71.7 ___ .19

.00 70.4 ___ .10

.01 70.8 ___ .13

.______ No Ne'

Apatite 1.630 -

Tremolite 1.624 1.610

.15 33.0 ___ 27.9

.01 31.0 ___ 24.9

.05 32.2 ___ 27.2

0 0.1mm

FIGURE 295. Weathered grains in adamellite soil thin section. Core of plagioclase (lower 

center to right center) is considerably altered. Microcline (upper center and upper right) 

has parted along cleavages and shows slight alteration. Quartz (left) is fresh. Crossed 

nicols.

often displaying considerable etching. Many grains 

show no such effects, however, suggesting that the more 

severely etched fragments, and perhaps the dolomite 

soil talc grains as well, may owe their modifications to 

an earlier and more intense period of weathering. Along 

edges and cleavages biotite (fig. 296) is altering to secondary products, which are discussed in the section

0.1mm

296. ^oil biotite grains (#86 soil, fine sand), showing both altered (upper left and 

upper center) and relatively unaltered margins (lower center). Plane light.
398 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

"Biotites." Biotites and epidotes have lost appreciable 

portions of their original margins, but irregular grain 

boundaries are only occasionally found on soil allanites. 

Microcline (fig. 295) and An10_ 15 plagioclase in the rims 

of normally zoned fragments commonly show some alteration to clay. Chlorite and apatite grains are frequently rounded, but are never deeply etched. Ilmenite 

and magnetite, especially the latter, may show minor 

external oxidation, but such changes are not common. 

Sphene, quartz (fig. 295), and muscovite display very 

little evidence of etching or alterations, but irregular 

boundaries not seen in bedrock grains are occasionally 

present. Soil zircons show perfectly euhedral margins. 

A seven-category weathering sequence for minerals in 

adamellite soils, based on the preceding evidence, is 

given in figure 297. In any given sample, a mineral may 

deviate from the sequence by one category, either above 

or below, but in general the order is consistent in all the 

samples studied. As in the case of the dolomite soils, 

quantitative mineral weathering studies were complicated by contaminants and yielded no substantial information not given by figure 297. In figure 305, mineral percentage changes with respect to bedrock are 

shown for the sand and silt fractions of #94 soil, a 

relatively uncontaminated site.

Qualitative data for phyllosilicates in the silt and 

clay fractions of some adamellite soils are summarized 

in table 7. Sericite, normal chlorite, and septechlorite 

are present in the silt fraction as well as in the clay and 

may be metamorphic or hydrothermal. Kaolinite and

2

sphene

Zircon> quartz > chlorite > plagioclase An ](,,,> .. > hornblende >plagioclase An... , muscovite muiLuvue magnetlte .. - 10-15 epidote 25-30 allanite 

ilmenite

Fu.i K_ 297. Mineral weathering sequence in adamellite soils of Sage Hen Flat, in order of 

decreasing resistance. Based on visual comparison of bedrock and noncontaminative soil 

grains. Vertical lines separate major divisions of resistance.

vermiculite are confined to clay fractions. As kaolinite 

occurs only in the adamellite soils, it is believed to be 

authigenic, but the vermiculite occurs widely and may 

have been partially or entirely added by aeolian processes. A small amount of montmorillonite is present in the 

clay fraction of one sample. The presence of several 

coexisting authigenic clay minerals, perhaps forming 

from different primary phases, is not inconsistent with 

the immature nature of the White Mountains soils.

ELECTRON MICROPRO BE STUDIES OF ADAMELLITE 

MINERAL WEATHERING

Seven minerals from adamellite bedrock, grus, and 

soil on Sage Hen Flat were chemically analyzed by 

electron microprobe. Biotite showed major weathering 

alteration; microcline, plagioclase, allanite, and some 

magnetite gave detectable changes; ilmenite and 

sphene yielded no measurable variations because of 

weathering.

BIOTITES

Biotite analyses reveal progressively lowered contents of K, Ba, Mg, and Si and increases in Fe and Al, 

from bedrock to grus to soil (table 8). Biotite in grus is 

chemically similar to fresh bedrock biotite, but both of 

these differ markedly from soil biotite grains (1-3 phi), 

suggesting that little chemical weathering of biotites 

occurs prior to or during grus formation. Decreases in 

grus Mg with respect to bedrock is apparently due to 

primary solid solution substitution of Fe for Mg rather 

than weathering losses. Some grus biotites, however, 

are obviously breaking apart along cleavages prior to 

chemical alteration.

In terms of lattice sites, the biotite cations in 

8-12-fold coordination appear to be the most vulnerable 

to weathering attack, followed by cations in octahedral 

coordination. (The values of table 8 assume no ferric 

iron is present and that all ferrous iron is in octahedral 

coordination.) Ions in sixfold and fourfold coordination 

taken together show little evidence of change. Within 

the 8-12-fold coordination sites, Ba appears to be more

TABLE 7. Layer silicates in silt and clay fractions of some adamellite soils

[x = present; 0 = absent; n.d. = not determined. Clay is < 2/_im soil fragments]

Sample number ____________ 42 91 92 95 99 101 102 106

Kaolinite:

Silt _

Clay __________________

Chlorite and (or)

septechlorite: 

Silt__ __ __ __ _____ __

Clay __________________

Vermiculite:

Silt____ _ __ __ _ ____ .

Clay __________________

Montmorillonite:

Silt_____ _ ___ _ _ ___ .

Clay __ ___ _____________

Sericite:

Silt .___ ______ _

Clay ________________

Biotite:

Silt- _ .___ _ __________

Clay ___________________

______ ______ n.d.

X

. ___ _ _ _ ___ n.d.

X

.__ _ _________ n.d.

_ _ __ . 0

._ _ _ _____ _ n.d.

0

_______________ n.d.

X

_______________ n.d.

X

0

0

X

X

0

X

0

0

X

X

X

X

n.d.

X

n.d.

0

n.d.

0

n.d.

0

n.d.

X

X

X

n.d.

X

n.d.

0

n.d.

X

n.d.

0

n.d.

X

X

X

n.d.

X

n.d.

0

n.d.

0

n.d.

0

n.d.

X

X

X

0

n.d.

X

n.d.

0

n.d.

0

0

X

X

X

X

n.d.

X

n.d.

0

n.d.

X

n.d.

0

n.d.

X

X

X

0

X

X

0

0

X

0

0

X

X

X

X

0

X

0

0

0

0

0

0

n.d.

X

X

X

0

n.d.

X

n.d.

0

n.d.

0

0

X

X

X

0

0

n.d.

(?)

n.d.

0

n.d.

0

n.d.

X

n.d.

X

n.d.

0

n.d.

X

n.d.

0

n.d.

0

0

X

X

X

X

0

n.d.

X

n.d.

0

n.d.

0

X.?)

X

(?)

X

(?)
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 399

TABLE 8. Averaged electron microprobe analyses of fresh and weathered biotites

[CN=coordination number with respect to oxygen]

Source 

of

analyzed 

grains

Fresh bedrock __

Soil (1-30 __ -

Elemental percentages

K

7.5 

7.3 

5.8

Ba

0.79 

.51 

.10

Mg

6.9 

5.8 

4.4

Fe

14.9 

15.8 

15.7

Al

7.5 

6.7 

13.7

Si

16.7 

16.5 

10.5

Total of 

analyzed 

elements 

as oxides1 

(percent)

90.4 

87.3 

82.9

Total: 

Annite +

phlogopite1 

molecules

81.6 

81.6 

73.3

CN=8tol2 CN=8

K+Ba

8.3 

7.8 

5.9

Mg+Fe

21.8 

21.6 

20.1

CN=4 to 6

Si+Al

24.2 

23.2 

24.2

CN=8 to 12

K/Ba

9.5 

14 

58

CN=8

Mg/Fe

0.46 

.37 

.28

CN=4 to 6

Si/Al

2.22 

2.46

.77

1 Assuming all Fe in ferrous state

easily mobilized than K, but the extremely low Ba 

counting rate precludes any definite conclusions. Mg in 

the octahedral site is obviously more mobile than Fe, 

and Si, largely located in the sixfold to fourfold site, is 

much more readily removed than Al, which occurs in 

both octahedral and tetrahedral positions.

Microprobe analyses are usually grouped and averaged to compare changes in more than three elements, 

because only three elements may be analyzed simultaneously and because it is virtually impossible to return to the same location on the same grain in a subsequent analysis. Soil grains may often contain appreciable unaltered parts, however, and primary compositional differences between grains may obscure changes 

due to weathering. Comparisons were made between 

weathered and fresh parts of the same soil grain to 

eliminate those problems. Ratios of K/Fe and Mg/Fe 

along five typical transects across soil biotites, both 

parallel and perpendicular to the (001) cleavage, are 

reproduced in figures 298 and 299. Several conclusions 

seem apparent from the data: (1) Lower K/Fe and 

Mg/Fe ratios invariably occur either along edges or 

cleavages, but every edge and cleavage does not show 

changed ratios, (2) traverses perpendicular to the basal 

cleavage are more variable than transects parallel to 

cleavages, and (3) K losses with respect to Fe are genei - 

ally more frequent and larger than those of Mg. Examination of the original data (not shown) reveals a relatively constant Fe percentage across the grains, indicating that Fe losses are comparatively minor. Decreased 

K/Fe and Mg/Fe ratios therefore reflect absolute losses, 

an observation consistent with the data of table 8. Some 

red-brown to yellow-brown Fe oxidation, though, was 

observed in soil biotites examined under the petrographic microscope, especially along grain margins.

To gain further information concerning the end product of biotite weathering, analyses of fresh and altered 

portions of soil biotites for Si, Al, and Ba were also 

conducted (table 9), using a finely focused electron 

beam. The Si/Al ratio drops from above 2 in fresh portions to less than 1, and even approaches 0 in the finegrained alteration products that commonly occur adjacent to edges and cleavages. Ba also shows somewhat 

lower values in the alteration products. The Mg losses

0.5

0.4

0.3

OR

05

04

Mg/Fe/^-' .^-' ~~ ~~ ' ~~ ]"\. 

_ _ .. _ .^ Cleavage'

l l l i 1

20 60 100

 Weathered ^ -~.. ^ - ,.~ -^,

\ I / ' ' " ' Cleavage

K/Fe/ '

-

III- GRAIN 1 - First traverse

140 18

' GRAIN ili- 1 -Second traverse

0.10

0.05

0 

0.15

0.10

n im

U. /

0.6

0.5

0.4

0.3

0.2

0.1

n

((-Weathered-*-.. ._..__ _ /Mg/Fe VMg/Fe '' ''' ~'~""\-\\ / * s:3'Z.'',^."~'s'*'.*-''~'£1 'Z'."/':*'- ~

A // K/Fe\\y N-/ " "cleavage" "^Cleavage" "'9^1 V\// " ~\ . / ^Cleavage

r\

GRAIN 2 - First traverse

i i l i i l i l

u.^u

0.15

0.10

0.05

0.00

URE

0.7 

0.6 

0.5 

0.4 

0.3 

C

0.6 

0.5 

0.4 

0.3 

0.2 

n 1

40 120 200 280 360 

/urn from left edge Gram! .right edge

298. Electron microprobe traverses normal to (001) cleavage of two soil 

grains.

i i ' 1 i i 1 i i 

,..__., . Mg/Fe\

K/Fel

GRAIN 1 '

~ i i i i i i i i r

) 40 80 120 160 200 240 280 320 36

 i J . I ._L__ l I i.i i J '._, i

XK/FB

/ Mg/Fe -I

^ GRAIN 2

I l l I | I l I l i I I

aiotite 

0.2

0.0 a 

3 it

0.1

0 40 80 120 160 200 240 280 320 360 400 440 480 

yum from top Lower edge

FIGURE. 299. Electron microprobe traverses parallel to (001) cleavage of two soil biotite

grains.

TABLE 9. Individual electron microprobe analyses, in weight percent, 

of altered and relatively fresh parts of soil biotites

Ba

0.10

.30

.00

04

.36

.00

.00

.00

Si

16.70

16.57

7.44

11.54

10.33

9.91

1.88

.86

.67

Al

7.38

7.55

9.17

14.80

15.10

18.57

16.88

22.43

29.91

Si/Al

2.26

2.19

.81

.78

.68

.53

.11

.04

.01

Description

Fresh

 do - 

 -do. 

 - do 

- do -

______________do___.______

______________do__________

Number of 

analyses

1

-___ 4

1

1

1

1

1

1

__ 1
400 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

and Si/Al ratios rule out vermiculite and montmorillonite as possible weathering products. The Si/Al ratios 

suggest that complete alteration to gibbsite may have 

occurred, but microprobe analyses of porous and probably hydrous materials such as these must be regarded 

with some caution. Four Si/Al values fall between 0.5 

and 1.0, and 1:1 clays (but not gibbsite) were detected in 

X-ray diffraction patterns of soil and clay fractions; so, 

the formation of kaolinite from biotite, if only as a 

temporary weathering product, seems a more likely 

possibility. Presence of colloidal, noncrystalline 

aluminum hydroxide may account for the low Si/Al 

ratios.

FELDSPARS

Microscopic evidence indicates that plagioclase, especially the more calcic zones, and microcline are altering 

to clays. The soil feldspars analyzed by the microprobe 

are much less severely altered than feldspars observed 

in some soil thin sections and grain mounts; so, chemical differences between averaged microprobe analyses 

of fresh bedrock grains and soil fragments (table 10) are 

not striking.

TABLE 10. Averaged electron microprobe analyses, in weight percent, 

of feldspars from fresh adamellite bedrock, grus, and soils

Ba Na Ca Fe

Number of 

Total: grains 

An+Ab+Or analyzed

Microcline: 

Fresh ________

Soil___ __ .__

Plagioclase: 

Fresh

Soil.. __ _

13.2 

13.0

13.0

.1

.2

.1

0.0 

.0

.0

.0

.0

.0

0.53 

.57

.31

6.9

6.4

6.5

0.01 

.01

.00

2.9

3.3

3.4

0.2 

.2

.2

.3

.0

.1

99.8 

99.2

96.4

99.4

98.0

1

4

2

4

2

8

The analyzed microclines appear to have undergone 

some chemical losses during weathering, as evidenced 

by the 3.4 percent decrease in molecular totals 

(An+Ab+Or), from bedrock to soil. Microcline grains 

from grus samples, like biotites (table 8), do not appear 

to be appreciably weathered. Microprobe transverses 

across K-feldspars from seven grus and soil samples 

(data not shown) suggest that lattice deficiencies, indicated by low molecular totals, most commonly occur 

near grain edges and that low Na and K values tend to 

be associated with these deficiencies. Primary crystal 

zonation, however, often obscures weathering losses.

Zoning is so prominent in the plagioclases that 

weathering changes are largely masked, but the 

molecular totals of table 10 indicate that losses due to 

weathering have occurred and that sodium may be the 

most mobile constituent. Plagioclases from both grus 

and soil appear to show detectable deficiencies of 

molecular totals. A very small electron beam was used 

to analyze fine-grained plagioclase alteration products 

within soil grains for Si and Al (fig. 300). The marked

< 25

Physical appearance of selected microprobe spot locations

1.5

FIGURE 300. Electron microprobe analyses of 10 parts of a single plagioclase grain.

decrease in Si/Al ratios from 2.7 in fresh portions to 

about 1-1.5 in altered areas suggests that kaolinite may 

be the principal weathering product. As weathering 

proceeds, Si percentages appear to decrease more 

rapidly than Al percentages increase, such that Si + Al 

steadily decreases.

OTHER MINERALS

Analyses of fresh and weathered allanite, magnetite, 

ilmenite, and sphene are compiled in table 11. The one 

soil allanite examined is lower in Ca and Al and higher 

in Fe percentage than fresh grains. Analytical results 

from 35 magnetite and ilmenite grains in both bedrock 

and soil gave little indication of weathering changes, 

but a few magnetite grains showed some visible alteration and less Fe (apparently due to oxidation) near their 

margins. Soil and bedrock sphenes gave virtually identical chemical analyses, and traverses across soil grains 

showed no significant variations.

TABLE 11. Electron microprobe analyses, in weight percent, of four 

minerals from fresh adamellite of Sage Hen Flat and from derived 

soil

Ca Mg Al

Number of 

analyses

Allanite:

Soil _ __ ___ ___

Magnetite: 

Fresh _

Soil _________ _ .

Ilmenite: 

Fresh

Soil _ _ _____ _ .

Sphene: 

Fresh __

Soil _____________

_______ 8.0

6.5

____ 23.3

..__ _ 23.8

0.00

.03

.05

.26

.0

11.5

12.9

70.8

72.6

32.2

30.0

1.2

8.2

6.7

.7

.9

0.13

.25

27.2

29.4

19.1

19.0

12

1

13

10

11

1

11

2

CHEMICAL CHANGES FROM BEDROCK TO SOIL

Chemical analyses of bedrock and soil samples were 

conducted by X-ray fluorescence techniques to assess 

the degree and sequence of bulk chemical changes due 

to weathering. For the adamellite and its derived soils, 

the U.S. Geological Survey samples G-l, G-2, GSP-1, 

AGV-1, BCR-1, and W-l were used as standards. The 

U.S. Bureau of Standards' Dolomite #88 and five Reed
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 401

bedrock and soil samples analyzed by Ken-ichiro Aoki, 

Tohoku University, Japan, were used as standards for 

the dolomite group.

REED DOLOMITE

Arithmetic means and standard deviations for 

analyses of dolomite bedrock, soil greater than 2 mm, 

soil less than 2 mm, and soil less than 62 /*m are given in 

table 12. Standard deviations refer to differences between samples collected at different locations rather 

than to analytical precision (replicate analysis).

The principal reason for collection of numerous and 

widely distributed bedrock and soil samples was to obtain an indication of chemical and mineralogical variability within each parent material and soil, such that 

changes due to weathering could be clearly differentiated from apparent changes caused by sampling 

deficiencies. Unfortunately, careful study of soil 

mineralogy shows most of the Reed soil samples to be 

contaminated by both rhyolitic ash and local materials 

to the extent that corrections for contamination would 

be meaningless. The effects of external aeolian addition 

are also indicated by the large increases in Na and K in 

the finer size fractions of the soils. Only one sample for 

which the mineralogy was determined, #65 soil less 

than 2 mm, appears to be little affected by contamination. Corrections for the minor chemical effects of the 

tuff and local contaminants in this sample were made 

using weighted averages of glass and contaminative 

mineral percentages3 in the sand and silt fractions (percentage clay was less than 1 percent and was therefore 

neglected in the calculations). Chemical composition of 

minerals and glass used to correct the original soil 

analysis are given, together with sources of information, in table 13. Local contaminants in this sample are 

assumed to be derived from the.nearby Sage Hen Flat

3The methods by which percentages of ash and aeolian contaminants were determined has 

been discussed elsewhere (Marchand, 1970) in some detail.

pluton. Soil analytical values from which corrections 

had been subtracted were recalculated to the previous 

oxide percentage total and converted back to elemental 

percentages. Total estimated contamination in #65 soil 

less than 2 mm is only 3.9 percent, and thus any errors 

due to inaccurate amounts of correction are relatively 

small.

Absolute losses (weight percent in bedrock minus 

weight percent in soil) are shown for the five 

carbonate-component elements in mean soil greater 

than 2 mm (hereafter termed "soil gravel") and #65 soil 

less than 2 mm (corrected for both ash and local contaminants) on the left side of table 14. To eliminate differential effects of heavy and light elements, the absolute 

losses are divided by atomic weight in the adjacent 

columns. Percentage losses with respect to bedrock, determined as

weight percent in bedrock-weight 

percent in soil

percentage loss =

weight percent in bedrock

are shown in bar graph form in the left side of figure 301. 

Both calculations were made holding constant the percentage of Zr, the most stable element during the 

weathering process for the samples studied here. Undoubtedly Zr percentage does change between bedrock 

and soil, but this assumption permits relative comparison of all elements investigated, the principal concern of 

this study. The soil gravel fraction is assumed to be 

little affected by contamination, and #65 soil less than 2 

mm has been corrected for all external additions; so, 

these two soil analyses should be chemically representative of Reed terrane. Elemental absolute losses from 

dolomite bedrock to soil follow the sequence Ca > 

Mg >» Fe » Mn » Sr, a trend strongly controlled by 

bedrock composition. When atomic weight is taken into 

account, the position of Ca and Mg in the sequence 

converge or trade places, but other relations remain

TABLE 12. Chemical analyses, in weight percent except as noted, of Reed Dolomite bedrock and soils 

[Data are from X-ray fluorescence techniques except as noted. n.d.=not 'determined; S.D.= standard deviation. Soil analyses are not corrected for contamination]

Bedrock Soil > 2 mm Soil < 2 mm Soil < 62 ju

Si

Ti

Zr

Al . __ ___ __ __.

Fe _ _____ __ __.

Mn _

Mg ________________

Ca __ _____ _ __

Ba _____ ._ _

Sr

Na1 _ ___ _____

K1

Rb _ ______ _

P2

Oxide total3

Mean

___ _ 0.11

__ _ .055

91 f^9

_ __ _ .027

.011

.0175

Number of 

S.D. samples

0.07 

.0050 

5.3

'.09 

.020 

.43 

.93

7 

.003 

.006 

2.00 

.0085

7 

6 

4 

6 

12 

12 

7 

12 

6 

6 

2 

2 

8 

2

498.63

Mean

0.80 

.022 

13 

.38 

.36 

.08 

11.01 

22.54 

.00 

62 

.0550 

.0545 

1.10 

n.d.

Number of 

S.D. samples

0.10 

.002 

3 

.06 

.005 

.01 

.16 

.43 

.00 

3 

.003 

.0055 

.50 

n.d.

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2

497.69

Mean

13.24 

.20 

104 

4.15 

1.83 

.11 

5.67 

12.93 

.028 

124 

.755 

1.281 

25.8 

.0545

S.D.

5.84 

.11 

51 

1.70 

.62 

.031 

1.57 

4.16 

.012 

27 

.395 

.335 

11.7

Number of 

samples

6 

6 

5 

6 

11 

11 

6 

11 

5 

5 

2 

3 

11 

2

5101.39

Mean

22.01 

.40 

246 

7.16 

3.13 

.12 

2.21 

8.38 

.06 

222 

n.d. 

n.d. 

51.0 

n.d.

Number of 

S.D. samples

1.00 

.02 

31 

.28 

.06 

.02 

.38 

.88 

.004 

17 

n.d. 

n.d. 

4.0 

n.d.

5 

5 

5 

5 

5 

5 

5 

5 

5 

5 

0 

0 

5 

0

694.63

1Flame photometer analyses by Joaquin Hampel.

2Wet chemical analyses by Ken-ichiro Aoki.

3CQi taken as stoichiometric. Iron computed as FezO.

4Includes H2 O+ and H2 O- analyzed by Ken-ichiro Aoki for three samples. 

5Includes H2 O+ and H2O analyzed by Ken-ichiro Aoki for two samples. 

6Does not include H2 O+ and H2O-.
402 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

TABLE 13. Chemical compositions, in weight percent except as noted, of minerals and glass in soils used to correct chemical analyses

[Probe analyses supplemented by data from Deer, Howie, and Zussman (1952a, b; 1963 a, b), as indicated, except analyses for volcanic glass and biotite, which are supplemented

by data from Carmichael (1967, p. 50 and 52, respectively) ]

Volcanic Plutonic (local)

Si ___ ___ ___

Ti

Zr _

Al ____ ___ ______

Fe __ _ _ ______

Mn _ ___ . ______

Mg __

Ca _

Sr __ ___

Ba __

Na _____ _ __ __

K _ __

Rb _____________________________

'&

a

O

04

 - ___ - _ ___ _____ _ 6.58

97

- _______ ___ __ ____ .04

02

. _ _ _ _ __ .43

Q AH

Q QQ

1

A

<D

!~ 1$

0^

 -".a

<DCO ^<o

CO

QA 7

.0

.4

Q A

1

'I

03 

K,

m o

73 «i

HBd

CO

QA O

64

19 '1 9

'6 9

'1.2

' 5 03 1 1

3.2

6.7

16.4

6.4 __

.01 ______

.5




1

§

.5

&S E"

CO 01

 -i.c

ffiCO 

< i en

&2 CO

03

30 1

10.1

.2

.01

.02

'.6

1

8

E

S

§,S

m co

g 

«)

29.6

.01

12.1

.06

'3.0

'6.8

'.1

.-B

iS

00

0

§ -

u

*£O*"S

S ^

«)

16.3

2.4

8.1

'14.8

.3 '6.4

.8

.3 '7.4

1

1

1

«J

1

 fip

gg

s°-

 H^J 

(U(N

Bs^

CO

22.5

.6

3.1 '9.9

.3 '7.7

'7.3

1.1

.6

1

CL W

Isg-d.

 as

Ed

w

17.4

.05

12.8 '9.2

'.03

16.5

5

H

O

5

°3^i--1

a 0-

"3^

S -i

CO

12.0

.53

11.2

'18.6

.27 '9.5

.11

'Analyzed by electron microprobe.

TABLE 14. Absolute losses, in weight percent, of chemical constituents 

from bedrock to soil, assuming constant Zr percentage

[Figures in parentheses under mean dolomite column are losses expressed as percentages of 

#65 bedrock-to-soil losses for the given elements]

Dolomite Adamellite

Mean dolomite bedrock minus #65 bedrock minus 

mean dolomite soil > 2 mm #65 soil < 2 mm1 

Flpmpnt

Si 

Al _ _ ___

K _ __

Na __

Fe________

Ca ______ 

Mg ______ 

Ti _ _____

Ba ______

Mn ______ 

Sr _ __ __

Rb ______

Absolute 

loss

- 0.08(67) 

-10.25(57) 

-6.96(65)

-.015(54) 

-.0025(65)

Loss/ 

atomic 

weight

-0.001 

-.256

-.286

-.00027 

-.000028

Absolute 

loss

-0.12 

-17.99 

-10.72

-.028 

-.0038

Loss/ 

atomic 

weight

A AAOO

-.449 

-.441

-.00051

#94 bedrock minus 

#94 soil < 2 mm1

Absolute 

loss

-16.67 

-4.33 

-2.12 

-1.77 

-.98 

-.92 

-.43 

-.09 

-.07

-.05 

-.0368 

-.0041

Loss/ 

atomic 

weight

-0.5934 

-.160 

-.0542 

-.0770 

-.017 

-.023 

-.01 

-.002 

-.0005 

-.0009 

-.000420 

-.000047

'Corrected for both ash and local contaminants.

essentially unchanged. Percentage losses, a more 

significant indication of weathering mobility, occur in

?

the sequence Mg > Ca > Sr > Mn~Fe. In the percentage 

loss calculation, the atomic weight factor is automatically taken into account. Loss of Mg relative to Ca, as 

indicated by the percentage losses, is in agreement with 

the presence of secondary calcium carbonate in dolomite soils. Comparisons of both absolute and percentage 

losses indicate that, of the five elements shown (with the 

possible exception of Mn), well over half of the total 

elemental losses in bedrock to soil less than 2 mm occur 

during the transformation of bedrock into soil gravel.

100

90

80

70

60

50

40

30

20

10

0

>;:.--.--;v--:--\. 

*.:'jj(65SO

ean soil >2mm

Mg Ca Sr Mn Fe Rb Na K Mg Sr Mn Ca Ba Si Al Fe Ti

FIGURE 301. Percentage chemical losses for the indicated Reed Dolomite and adamellite 

soils of Sage Hen Flat with respect to bedrock, assuming constant Zr percentage. 'Corrected 

for both ash and local contamination.

Obviously chemical breakdown of the dolomite begins 

almost simultaneously with physical disintegration in 

the early stages of the carbonate weathering process. 

Sections cut through spheroidally weathered dolomite fragments occurring at the surface or within the 

soil profile commonly show an abrupt change from fresh 

light cream to pink crystalline dolomite outward into a
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA

porous gray or white concentrically layered weathering 

rind (fig. 302). Under the petrographic microscope, alternating layers of fresh dolomite and a fine-grained 

alteration product are evident within the rind. Electron 

microprobe analyses of one of the rinds for Ca, Mg, Mn, 

and Fe and microprobe transects from unaltered dolomite into the rind (figs. 303, 304) indicate that the 

weathering product is a very pure calcite, as shown in 

the following table.

FIGURE 302. Rock saw chips showing weathering rind on spheroidally weathered dolomite 

(#68) analyzed by electron microprobe. Rind is about 0.2 inch thick.

 WEATHERED RINDFresh grains

-FRESH DOLOMITEBoundary

3000

2500

2000

1500

300

250

200

150

100

50

0

Mg

Horizontal distances not to scale, total width approximately 1 cm

CaO

Fresh dolomite ______ percent._ 30.2 

Alteration product ___ percent__ 54.1

MgO

20.6 

.3

MnO

0.3 

.2

403

FeO

0.2 

.1

Leaching of Mg and deposition of calcite are undoubtedly responsible for the development of carbonate horizons and other calcium carbonate accumulations in 

dolomite soils. Fe and Mn are more variable within the 

rind, but appear to occur in approximately equal concentrations in both dolomite and calcite.

ADAMELLITE OF SAGE HEN FLAT

Mean analytical values for bedrock, grus, soil less 

than 2 mm, and soil less than 2 ^m are given in table 15. 

The grus values are generally comparable to those of 

the bedrock, and where they differ, the direction of 

change suggests primary variability rather than 

weathering. Therefore, in the third column of table 15, 

means weighted on the basis of number of samples have 

been calculated for both bedrock and grus and were used 

as the bedrock values in all further computations.

As in the case of the Reed, almost all adamellite soils 

are greatly contaminated by both rhyolitic ash and local 

debris. The first step in preparing the soil analyses for 

interpretation was to correct for the contaminating ash. 

After ash correction, only #94 < 2 mm gave a reasonable sequence of bedrock-to-soil mineralogical changes, 

on the basis of grain counts (fig. 305), suggesting ab-

-WEATHERED RINDFresh grains

-FRESH DOLOMITEBoundary

Mg

L

Horizontal distances not to scale, total width approximately 1 cm

FIGURE 303. Electron microprobe transect showing Ca, Mg, anu j'e variation across an FIGURE 304. Electron microprobe transect for Ca, Mg, and Mn across dolomite weathering 

alteration rind in spheroidally weathered Reed Dolomite (#68). rind (#68).
404 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

TABLE 15. Averaged values for X-ray fluorescence chemical analyses, in weight percent except as noted, of adamellite

bedrock and soils of Sage Hen Flat

[S.D.=standard deviation; n.d.=not determined. Soil analyses are uncorrected for contamination]

Si

Ti

Zr ______

Al

Fe _____ _

Mn __ __ _ _____ __

Mg ________________________

Ca _ __ _ __ __ __

Ba ___ __ _______ _____ __

Sr

Na _ - __ __ __ __

K ___ __ _ _ _ _

Rb _

P

C _ _ _ _

H _ _ _ __ __ __ __ __

Number of total

Number of partial

"Bedrock" (= 

weighted average 

of bedrock and 

Bedrock Grus grus; see text) Soil < 2 mm Soil < 62 //m

Mean S.D. Mean S.D. Mean S.D. Mean S.D. Mean S.D.

32.39 0.98 31.16 1.67 31.79 1.08 31.51 0.61 28.21 0.85

.24 .04 .23 .04 .24 .04 .32 .05 .51 .03

ppm 164 32 123 16 152 27 217 49 517 65

8.36 .41 8.94 .50 8.53 .44 8.03 .55 8.38 .22

__ __ _ _______ _ _ 2.16 .56 1.55 .04 1.99 .41 2.77 .62 4.53 .50

.06 .02 .05 .04 .06 .03 .08 .02 .12 .01

.__ __ _ . __ _ _ .46 .18 .31 .03 .42 .14 .56 .12 1.32 .22

__ . ______ ___ _____ _ _ 1.44 .29 1.45 .09 1.44 .23 1.32 .17 2.24 .12

.12 .02 .15 .05 .13 .03 .10 .01 .08 .01

ppm 600 111 533 129 581 116 455 91 321 21

_ _ _ _ 2.70 .24 2.53 .23 2.65 .24 2.19 .14 1.57 .10

. __ _ _ __ _ __ 3.20 .45 4.41 .84 3.55 .56 3.00 .24 2.97 .06

ppm 53.9 12.9 65.3 12.8 57.1 12.9 59.8 8.0 67.3 1.9

__ _____ . '.048 _ _ n.d. '.048 _ ".0455 _ _ n.d. - _ _

1 .05S n.d. '.053 22.04 n.d.

10020 9773 99.32 100.47 94.89

10 4 14 6 _ _ 5

8 0 8 5 _ 2 _ _ .

1Based on one wet chemical analysis by Ken-ichiro Aoki. 

"Based on two wet chemical analyses by Ken-ichiro Aoki.

lu l l i i 

o'

10" -

o 

o

X

LU o

*g 103 QZ OA LU° 3 ^ X H

£ oo EXPLANATION 

I ? OSand X Silt (3 H

 2 Al Allanite u 

§y A Apatite °H X B 

Jj CC 10 2 _ B Biotite

- _, C Chlorite 0 M9 x,-, C_) O^ t/31 E Epidote

Z g H Hornblende 

1- [0 1 llmenite 

^ § M Microcline 

° ^ 10' - MS Magnetite 

LU O Ms Muscovite 

^ ° | P Plagioclase 

X D £ Q Quartz 

^2 m 'm S Sphene 

> Z Z Zircon 

^ r\ l 1 l l

LU

i 1 LU O 

0 -1

rr l

LU t 

D. -10 1 - 

-10 2 L_

' 

0 Ms

Oc Q E ° - 

X M

1 ° AI 1 l

0.001 0.01 0.1 1 10 1C

PERCENT IN BEDROCK

FIGURE 305. Mineral percentage changes with respect to bedrock in two size fractions oft 

relatively uncontaminated adamellite soil L#94>, after ash corrections.

3Fe calculated as Fe.O3 ; H2O+, H2O-, P2OS , COa not analyzed in grus and < 62 fun 

soil samples.

sence of significant local contamination. All major minerals except biotite and hornblende appear in place in 

the #94 sand and #94 silt mineral sequences, based on 

the observed weathering sequence (cf. fig. 297). By 

using percentage changes consistent with those of 

quartz, microcline, and plagioclase and with the observed weathering sequence, corrections were computed for biotite and hornblende in the less-than-2-mm 

fraction of #94 soil, as shown in the left part of table 16. 

Chemical corrections using the values of table 13 assume that the biotite and hornblende came from the 

Sage Hen Flat pluton or do not differ greatly from that 

of the pluton. The adjustments, including those from the 

ash, were subtracted from the original analysis of #94 

soil, followed by correction to the previous oxide total 

and reconversion to elemental values, as shown in the 

right part of table 16. 

Chemical changes due to weathering at site 94 may 

now be assessed from bedrock and corrected soil analyses. Absolute losses and losses divided by atomic weight 

from #94 bedrock to less-than-2-mm soil are given on 

the right side of table 14. Percentage losses with respect 

to bedrock, computed from concentrations in weight 

percent and assuming constant Zr percentage, are presented graphically in figure 301 (right side). Bedrock- to0 soil absolute losses occur in the sequence Si » Al > K > 

Na > Fe > Ca > Mg » Ti > Ba > Mn > Sr » Rb, in 

close accordance with bedrock abundances. Absolute 

losses adjusted for atomic weight yield a slightly different sequence, Si » Al > Na > K > Ca > Mg >
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 405

TABLE 16. Adamellite sample 94-bedrock chemical analysis and adjustment of < 2-mm-soil analysis for ash and local

contamination by biotite and hornblende

[All analytical data in weight percent, except as noted]

94 sand:

Hornblende

a.

"a! 10

JS" 

o

-1.8

+200

£ .a ? !

1 g 8 g

< OH

-30 6.7

-40 .13

8 1

.5 >

g 1 

£ *

£ S

.42 .08

Difference

-3.5

-.34

Weighted average

_3

Local 

compone

"S

Ash 

compone

 sU1 

 c g

O cS

Correction for ash

m -H

Correctior local forcontaminal Analysis corrections

S^2

^s°

rj O 4_) 3 g e c

1 S IPQl PH Q>

o "-S"3

Corrected element 

values Bedrock analysis

94 silt:

Biotite _______ +170 

Hornblende _____ +1,050

94 soil <2mm: 

Biotite

-35

-45 6.7 

.13

4.4 

.07

-10.6 

-6.93

Hornblende _

Si ________________ ________ ____ ____ ____ ____

Ti ________________ ______ _ ___

Al _

Fe _______ __ _____ ______

Mn________________ ________ ___ ____

Mg________________ ________ ____ ____ ____ ____

Ca __________ ___

Ba __ _ __ __

K __

______ -.97 -.97 -__

0110

______ ____ ____ ____ .40

 _ _ _ 308

q HK.

______ ____ ____ ____ .09

______ _ _ -__ -__ .71

AQ

______ ____ ____ ____ 2.07

-.02

-24

-1.62 -.26

-.01

-.02

.10

.005

1

-.99

-43

 0 94

-.39

-.75

-.02

-.36

-.02

 34

21.60

6.34

.06

00

1.08

AQC

1.32

1.62

19.3

46.21

.45

11.98

3.92

.08

1.51

434

1.78

1.95

42.2

.64

546

17.02

5.57

.12

.78

2.15

617

2.53

2.77

60.0

.38

404

9.01

3.90

.09

.47

1.54

.12

522

1.88

2.30

27.4

.28

198

8.75

2.89

.09

.66

1.67

.13

624

2.69

3.25

54.0

Fe » Ti > Mn > Ba > Sr » Rb. Percentage losses, 

the most significant indicator of chemical behavior

?

during weathering, follow the sequence Rb > Na ~ 

K ~ Mg > Sr > Mn « Ca > Ba > Si > Al » Fe > Ti. 

The placement of Rb within the latter sequence is 

somewhat uncertain owing to its low concentration in 

both bedrock and soil and to its susceptibility to contamination from biotite, feldspars, and glass.

Examination of figure 301 shows that percentage 

chemical losses generally follow the sequence alkali 

metals > alkaline earths > Si > Al > metals. Some 

notable differences in element mobility between the 

dolomite and adamellite are also evident. Greater absolute amounts of Sr, Fe, and Mn are lost from adamellite 

than from dolomite, whereas Ca, Mg, Sr, Mn, and Fe all 

undergo greater percentage losses from dolomite bedrock to less-than-2-mm soil than from adamellite bedrock to less-than-2-mm soil. The soluble dolomite obviously releases all its constituent elements more readily 

than they can be weathered from silicate and oxide 

phases in the plutonic rock.

The preceding interpretations are based on bedrockto-soil changes recorded at only two sites, although 

mean dolomite soil gravel values and microprobe 

analyses of both dolomite and adamellite minerals give 

additional confidence to the patterns of chemical 

weathering. The extensive soil contamination rendered 

study of all other samples virtually meaningless. For 

confirmation of the chemical weathering sequences 

suggested by the limited data provided by bulk changes

in the solid phases, it was necessary to examine the 

chemical composition of natural waters related to both 

dolomite and adamellite.

CHANGES IN THE LIQUID PHASE

Chemical weathering usually occurs only in the presence of a liquid phase which is undersaturated with 

respect to the altering phases. A considerable amount of 

information concerning processes and sequences of decomposition can be obtained from observations of progressive chemical changes in water as it passes from the 

form of precipitation into soil water and finally into 

ground water and springs. The following discussion 

considers the chemical nature of rain and snow water, 

soil water extracts, and spring waters related to both 

dolomite and adamellite, the saturation pH and exchangeable cations of the soils, and finally the 

significance of geochemical differences between the various fluids in terms of chemical weathering.

CHEMICAL COMPOSITION OF PRECIPITATION

Four rain samples and four snow samples, obtained 

during the period July 30,1966, to June 29,1967, were 

collected in plastic-lined pans and filtered through 

0.45-Mm filter membranes into airtight polyethylene 

containers. The analytical data4 for these samples, together with mean values for Sierra Nevada snow, are 

given in table 17. The White Mountains samples tend to

"The procedures of Barnes (1964) were followed for field determination of pH and alkalinity 

for all water samples. All other chemical analyses of water were performed by the U.S. 

Geological Survey.
406 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

TABLE 17. Chemical analyses, in milligrams per liter except as noted, 

of precipitation collected near Crooked Creek Station and comparison with analyses of snow from the east slope of the Sierra 

Nevada

[Mean for snow from Feth, Rogers, and Robinson (1964, p. 18-26) ]

Crooked Creek Station

K- _

Na _

Ca_

Mg_

Ba_

Mn_

Fe

Al

B_

SiO2.

HCO3_ NO3 _

SOI PO4 _

CL

Mean1 + 

standard 

deviation

.14 +.10

.34 +25

.36+. 12

.9 +.07

_ <.5

.003 +.002

.014 +.010

.012 +.011

.01

.11 +.06

_ 2.7+1.3

.2+.0

06+09

.00 +.00

Maximum

11 

.31 

.90

.57 

.22

.006 

.024 

.032 

.02 

.2 

4.3 

.2 

.2 

.00 

.7

Minimum

4 

.06 

.16 

.23 

.034

.000 

.000 

.001 

.00 

.035 

1.2 

.2 

.0 

.00 

.2

Mean 

for snow, 

east slope 

of Sierra 

Nevada

.41 

.43 

.84 

.19

2 .00 

2 .01 

2 .03 

2 .05 

2 .17 

3.59 

2 .07 

1.14 

2 .03 

.47

'Mean for four rain and three snow samples. 

2Value for entire Sierra Nevada.

have lower mean concentrations of most constituents, 

especially sulfate, than do the Sierra samples. Mn, Fe, 

Cl, and nitrate are comparable or slightly higher in the 

White Mountains.

CHEMICAL COMPOSITION OF SOIL WATER

Obtaining representative soil water samples is a considerable problem that has been approached from several angles. Lysimeters and other elaborate devices 

probably collect the most typical fluids, but they are 

often difficult to install and maintain and give no indication of geographical variation unless employed in 

large numbers. In the White Mountains, soils are either 

dry or frozen except for brief periods during spring 

snowmelt and after very heavy summer storms, making 

field collections difficult to obtain. For this study, water 

saturation pastes of 46 Reed Dolomite soils and adamellite soils of Sage Hen Flat were prepared, and after 1 

hour water samples were vacuum-extracted by Buchner 

funnel in the laboratory. (See section "Supplemental 

Information" for methods). Saturation, rather than excess water mixtures, was chosen for initial soil moisture 

content in the belief that this would more closely reflect 

actual soil water conditions. Distilled water was used in 

all extractions, the assumption being that any differences between precipitation and distilled water, with 

regard to the analyzed species, would not be significant 

in comparison to the soil water concentrations.

Analyses of these extracts, summarized in table 18, 

indicate that standard deviations within a given soil 

type are often nearly as large as or larger than differences between soil types. Comparison between some 

chemical species of the two soil water groups, however, 

is still possible. The adamellite extracts are lower in Ca

TABLE 18. Chemical constituents in water saturation extracts of two 

groups of White Mountains soils

[All analytical values other than pH are in milligrams per liter]

Standard Number of 

Mean deviation High Low analyses

Reed Dolomite

K _ _ ________

Na ______ _ ____ ...

Ca ___-__-____.____._-.

Mg - .

PO4 _____ _ _____ ...

Na/K ___ - __ _ ___ .

Field pH _____ . _ _

. _ , _ 13

. __ __ 100

. ____ 21

. ____ .0082

. ____ 1.00

. ____ 4.8

+8 43

+4 24

+29 150

+6 33

.0052

5.5

7.1

42

7.0

,0210 .0021

O A \

33

33

33

23

11

Adamellite of Sage Hen Flat

K . 

Na _ 

Ca __ 

Mg . _ 

Fe _ ________ 

Si 

PO4 __ . _ .. __._

Na/K ____ , ___ . 

Ca/Mg ... ___ - ___

Field pH. _________ -

_ . 22

. _ 14

__ ... 61

___ .. 10

_ _ ,24

____ 10.1

.0150

____ .64

6.1

±9

+4

±22 

+3

±.10 

+ 1.3

.0040

94 

26 

110 

17

14

9.8 

7.4 

28 

5.6 

.56 .12 

8.0 

.0190 .0110

68

23 

23 

23 

22 

20 

21 

2

m paste

and Mg and apparently higher in K and phosphate than 

the Reed samples. Na is surprisingly low in the adamellite soil water extracts.

The large deviations in soil water composition, which 

exceed the standard deviations in total soil composition 

(compare table 19 with tables 12 and 15), imply considerable departures from equilibrium and steady state 

(rate of ion gains = rate of ion losses) conditions, 

perhaps accentuated by the relatively short duration of 

the extraction process. For this reason, soil water extractions may differ to some extent, primarily in degree 

of variability between sites but probably in ionic proportions as well, from meteoric water that has been in 

contact with the soil for several days or weeks during 

snowmelt or after heavy rains.

SOIL pH

Table 19 gives a compilation of field and laboratory 

pH data for Reed Dolomite soils and adamellite soils of 

Sage Hen Flat. These data, together with similar information from basalt and sandstone soils in the area, 

indicate that instrumental laboratory pH values and 

indicator-determined field pH values are comparable to 

pH's about 8.0, where the field methods begin to give 

consistently higher readings. A comparison of the 

figures for the two soil types shows the Reed soils to 

have values 0.5-1.5 pH units higher than the adamellite soils.

EXCHANGEABLE CATIONS

Amounts of total extractable soil cations (in milliequivalents per 100 grams of ovendry soil) were ob-
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 407

TABLE 19. Mean values for total exchangeable cations, percentage 

exchangeable cations, and pH in Reed Dolomite and adamellite 

soils of Sage Hen Flat

Standard 

Mean deviation

Standard 

deviation 

(% of mean)

Number of 

samples

Reed Dolomite soils

pH:

Average maximum field _ _ _ 

Average minimum field _____

Exchangeable cations 

(me/100 g ovendry soil):

Na. _ .

Ca_

Mg. _ _ _

Percent of exchangeable cations: 

KL

Na.

Ca_

Mg. _____ _ _

8.0 0.1 

8.2 .1 

7.9 .01 

7.5 .2

.58 .30 

.27 .09 

32.4 13.3 

6.1 2.5

1.6 .9 

.73 .27 

80.7 7.6 

16.9 6.7

1

1 

5 

3

52 

33

41 

41

56 

37 

9 

40

25 

25 

25 

25

25 

25 

25 

25

21 

21 

21 

21

Adamellite soils

pH: 

Average mean field _

Average maximum field __ __ 

Average minimum field __ __

Exchangeable cations 

(me /1 00 g ovendry soil): 

KL

Na_

Ca_

Mg.

Percent of exchangeable cations: 

KL

Na. _

Ca_

Mg__ __ _

6.8 0.5 

7.6 .6 

6.2 .5 

7.0 .4

.33 .13 

.07 .05 

7.7 2.5 

1.09 .34

3.8 1.8 

.70 .25 

83.2 4.2 

12.2 3.3

8 

8 

7 

5

40 

69 

31 

31

47 

33 

5 

27

22 

22 

22 

22

22 

22 

22 

22

21 

21 

21 

21

tained by repetitive leaching with 1.0 N NHtAc at 

pH=7.0. (See "Supplemental Information" for details.) 

Values for exchangeable cations (table 19) were calculated from the total extractable and water-soluble cations as follows:

Exchangeable cations=total (NH4Ac) extractable

cations cations in water 

saturation extracts (all 

values in milliequivalents 

per 100 grams of dry soil).

The exchangeable cations were then recalculated to 100 

percent (table 19). The adamellite soils are much lower 

than Reed soils in amounts of all exchangeable cations; 

they are higher in percentage exchangeable K, slightly 

higher in percentage Ca, comparable in Na percentage, 

and somewhat lower in percentage Mg.

CHEMICAL COMPOSITION OF SPRING WATERS

Water samples from four springs related to Reed 

Dolomite and adamellite of Sage Hen Flat were collected during the summer and fall of 1966 and during 

the summer of 1967. Water samples were filtered 

through 0.45-/nm filters into airtight polyethylene containers. The samples were usually collected near sunrise or sunset to minimize air-water temperature differences, which would affect pH measurements. A part of 

each sample collected during the summer of 1967 was

acidified to pH 2 to prevent precipitation of metals and 

was used for analysis of Al, Fe, and Mn. Al values are 

markedly higher for the 1967 samples, reflecting either 

precipitation of Al in previously collected samples or 

solution of particles less than 0.45 ^m in the acidified 

parts. There was relatively good agreement of Fe and Al 

values in the 1967 samples with those reported for 

granitic waters in the Sierra Nevada by Feth, Roberson, 

and Polzer (1964). Changes caused by orifice location, 

diurnal variation, and seasonal fluctuation at a given 

spring were found to be negligible compared with differences between springs.

WATERS RELATED IN PART TO THE REED DOLOMITE

Poison Creek Spring emerges from the east side of a 

canyon wall about 400 feet east of the Wyman-Reed 

contact, which dips about 60° westward at this location. 

The spring water would appear to be chemically controlled in large part by the dolomite, which crops out 

continuously for several miles west of the Wyman contact, but the water is also influenced to a lesser degree 

by the sandstones, shales, and limestones near the 

orifice. Waters emerge from three orifices (herein designated A, B, and C, from south to north) about 15 feet 

apart. Discharge from orifice C, the major outlet, averages about 0.1 cfs (cubic feet per second), as measured 

with a Pygmy current meter.

Cotton wood Spring, the principal source of the south 

fork of Cottonwood Creek, is in a valley that partially 

separates the Reed Dolomite from the Cottonwood pluton. The orifice lies within the Reed, though, and the 

apparent catchment basin is dominated by dolomite. 

Discharge is quite constant at about 1.8-2.0 cfs.

Analytical data for these two sampling locations are 

summarized in table 20. The predominant ions are Ca,

TABLE 20. Field and laboratory analytical data for two natural 

waters associated in part with the Reed Dolomite

[All concentrations in milligram per liter]

Poison Creek Spring

Mean

Field pH

Na+.

Ca++_

Mg++_

Ba++ _ - 

Mn_

Fe.

AL

B_

Field HCOa - -

so4 -2_

PC-4-3

Water temperature __ __ (°CJ_

7.71 

J286 

.99 

3.35 

29 

14.9

i!ooi

13'

175'

7.8 

'.00 

5.8 

2.84 

3.06 

7

Standard 

deviation

0.14

.03 

.09 

2 

.3

.5

7

.7

.3

Cottonwood Spring

Mean

7.72 

*252 

.81 

1.54 

24 

15.9

.004 

.043 

.013 

9.0 

.01 

.6 

162

'.3

3.1 

U2 

6.9 

2.59 

2.75 

6

Standard 

deviation

0.27

.01 

.07 

1 

.1

.2

4

.1

1.0

1Based on one analysis.
408 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Mg, and bicarbonate; Na and sulfate are quite low. 

Poison Creek Spring shows the influence of the Wyman 

beds in its increased Na, K, Si, and sulfate with respect 

to the Cottonwood samples, and its higher Ca/Mg ratio 

reflects the presence of limestones near the orifice. The 

pH of Poison Creek is the same as that of Cottonwood 

Spring, however, and in most respects the waters of the 

two springs are similar.

WATERS RELATED LARGELY TO THE ADAMELLITE OF SAGE HEN FLAT

Sage Hen Spring and Crooked Creek Spring appear to 

be almost entirely related to the Sage Hen Flat pluton. 

Formations adjacent to the adamellites, such as the 

Wyman Formation, Reed Dolomite, Deep Spring Formation, or Campito Formation could have some slight 

effect on the chemical composition of these waters. Discharge at Sage Hen Spring is about 0.1 cfs, but 

fluctuates appreciably. Discharge at Crooked Creek 

Spring is even smaller, its mean about 0.05 cfs or less.

Analytical data for the two sampling sites related to 

the adamellite are given in table 21. Crooked Creek 

Spring has a higher pH than Sage Hen Spring and 

contains less Mg and slightly less Na. The fact that the 

two waters, draining the same plutonic body, can be 

consistently distinguished chemically is an indication 

of the sensitivity of natural water to variation in bedrock composition and weathering conditions. The 

adamellite-derived spring waters, however, are virtually identical in most other respects and contrast 

sharply with those related to dolomite. Waters draining 

the adamellite are much higher in Na, sulfate, and 

chloride than are the dolomite waters and much lower 

in Ca, Mg, and bicarbonate. The pH values of the four 

spring waters are almost the same except for Crooked

TABLE 21. Field and laboratory analytical data for two natural waters

associated with the adamellite of Sage Hen Flat

[All concentrations in milligrams per liter]

Crooked Creek Spring Sage Hen Spring

Standard 

Mean deviation

Standard 

Mean deviation

Field pH.

K+ 

Na+-

Ca++-

Mg+ +

Ba+ +

Mn.

Fe.

AL_

SiCV

B _

C1-- - _ _

Field HCCV- _ .

NOT. - -

sex,- 2

PC\-i

7.96 0.15

U29

.79 .05

6.23 .19

17 1

.93 .08

2<.5

i.OU

1 .014

15.4 .8

i.OlS i 9

61 3

'3.3

9.8 .5

'.145

5.6 .1

1.22

1.29

13

7.72 '127

.64

6.56

1.55 2<.5

i.OOO

1 019

^OSS

16.4'.01

'.85

60'.8

9.4

Ml

1.24

7

0.11

.02

.16

.08

.5

1

1.1

.1

Creek Spring, which is more alkaline than either of the 

springs related to the dolomite.

ANALYSIS OF CHEMICAL CHANGES

For purposes of analysis and interpretation, the 

chemical data for natural waters related to both dolomite and adamellite are viewed in the following discussion from three perspectives: (1) Relative mobilities, 

showing the degree to which the various chemical 

species are mobilized from bedrock by weathering and 

released into solution, (2) stability with respect to some 

important solid and gas phases, including a discussion 

of water chemistry in relation to several equilibrium 

reactions, and (3) a chemical comparison of soil water 

with precipitation and spring waters.

RELATIVE MOBILITIES

A common means of evaluating the ease with which 

various chemical constituents are released by weathering from bedrock to ground water is through the calculation of relative mobility:

Relative mobility 

(element X)

Percent X of N-element 

total in water_________

Percent X of N-element 

total in bedrock

1Based on two analyses. 

2Based on one analysis.

where N is the number of elements considered. This 

computation assumes that a given water can be 

definitely correlated with a given lithology, that the 

mean analytical values for that lithology are representative, and that the composition of the water with regard to the investigated constituents is entirely a function of contact with the bedrock material. It is likely 

that the waters sampled in the White Mountains have 

been affected to some extent by windblown contaminants and the rhyolitic ash, but evidence presented here 

(see "Relationship of Soil Water to Precipitation and 

Spring Waters") suggests that major influences on 

ground-water composition occur after percolation 

through the soil.

Relative mobilities calculated for Cottonwood Spring 

with respect to dolomite bedrock (table 22) fall into the 

sequence Mg > Ca » Fe > Mn. Mobilities of other 

elements, for example, Si, Al, Ti, Na, and K, are more 

susceptible to influence by weathering of contaminants 

than of the bedrock, which contains only trace amounts 

of these constituents. Interpretation is therefore 

confined to the carbonate-component elements. The relative mobility sequence of table 22 agrees well with the 

order of percentage losses from dolomite bedrock to soil 

(cf. fig. 301), except that the mobility of Fe in dolomite is 

clearly greater than that of Mn, a relation not evident 

from solid-phase considerations.

In figure 306, ranges of relative mobilities for eight 

elements, based on analytical means and standard de-
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 4Q9

TABLE 22. Relative mobilities for four elements in Cottonwood 

Spring waters

Mg Ca Fe Mn

Concentration in bedrock_________percent.. 12.46 21.52 0.26 0.055 

Concentration in

Cottonwood Spring water_________mg/l_. 15.9 24 .043 .004 

Percent of four-element total (bedrock) ______ 36.33 62.75 .76 .16 

Percent of four-element total (spring) ______ 39.79 60.08 .108 .010 

Relative mobility .._____________.___ 1.095 .957 .142 .063

Ca

B

B

EXPLANATION

A Sage Hen Spring

o Crooked Creek Spring

Note: Overlapping ranges 

are offset for clarity

0.05

MEAN PERCENTAGE IN BEDROCK

FIGURE 306 Relative mobilities for eight elements in spring waters related to adamellite. 

Vertical bars indicate ranges of values.

viations at Crooked Creek Spring and Sage Hen Spring, 

are plotted against mean bedrock percentage on a loglog scale. The horizontal scale serves to emphasize the 

importance of the various constituents with regard to 

bedrock weathering and to their net contribution to the 

ground water. Elements plotting in the upper right of 

the diagram (Ca, Na, and Si in this case) are mobile 

constituents present in appreciable quantities in the 

bedrock and will be liberated in relatively large total 

amounts to the ground water. Elements that plot toward the lower left (such as Mn) are comparatively 

immobile, are not abundant in the adamellite, and are

therefore released to the ground water in trace 

amounts.

The apparent sequence of mobilities for the adamellite-draining springs is Ca > Mg ~ Na » Si ~ K ^ 

Mn x Fe > Al. Values for Mn, and to some extent for Mg, 

vary considerably between the two springs, making the 

placement of these elements within the order somewhat 

uncertain. The results as a whole are in good agreement 

with those of Feth, Roberson, and Polzer (1964) for 

quartz monzonite (adamellite) terrane in the Sierra 

Nevada and are generally similar to losses from bedrock 

to soil (table 14; fig. 301). The relative positions of Ca, 

Mg, and Na in the weathering sequence differ, however, 

between the solid phase and liquid phase perspectives. 

Considering the problems of soil contamination, one 

possibility is that carbonate grains may be continually 

blown into adamellite soils and quickly dissolved, resulting in increased Ca and Mg concentrations in waters draining the pluton. Only a few carbonate fragments were observed in adamellite soils; however, soluble grains (especially those reactive fragments of silt or 

clay size) would not be expected to persist in nonsoluble 

soils, and both dolomite and calcite were found in dust 

trap residues collected within the area (Marchand, 

1970). Ruhe (1967, p. 57-59) suggested solution of 

windblown contaminants to explain the formation of 

thick caliche horizons in soils formed on low-Ca parent 

materials in New Mexico.

STABILITY WITH RESPECT To SOLID AND GAS PHASESS

By using means and standard deviations for ion concentrations, pH, and temperature from Cottonwood 

Spring and Poison Creek Spring, maximum, minimum, 

and most probable values of ion-activity products (IAP) 

were calculated for both calcite and dolomite as follows:

and

IAP =

IAPd =

where [a] is the ionic activity of the solutions (approximately equal to concentration). A comparison of the 

spring waters with regard to carbonate equilibria is 

presented in table 23. All waters are undersaturated 

with regard to both calcite and dolomite, yet minor 

amounts of calcium carbonate have precipitated on exposed rocks near all the springs sampled. Calcite lacks 

saturation by a factor of about 2.5-10 in the dolomite5Sources for physical constants used in calculations: 

Ki first carbonic acid dissociation; Harned and Davis (1943, p. 2030). 

Kz second carbonic acid dissociation; Harned and Scholes (1941, p. 1708). 

.KCQj graphical solution, using data of Markham and Kobe (1941, p. 449). 

A first constant, Debye-Huckel equation; Manov, Bates, Hamer, and Acree (1943, p. 1765). 

Kc calcite equilibrium constant; Larson and Buswell (1942, p. 1667). 

Kd dolomite equilibrium constant; (Hsu, 1964).
410 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

TABLE 23. Degree of saturation with respect to calcite and dolomite 

for four spring waters

[Ranges of values reflect temperature and compositional extremes. M.P. = most probable 

value; IAP = ion-activity product]

Cottonwood Poison Creek Crooked Creek Sage Hen 

Spring Spring Spring Spring

lAPc: 

Maximum

M.P. ___________

Minimum

Kc1 : Maximum

M.P. ____ ___ .

Minimum

lAPc/Kc: 

Maximum

M.P. __ _

Minimum

lAPd: 

Maximum __ . .

M.P. _ .

Minimum

ffd2 -

lAPd/tfd: 

Maximum

M.P. _____ __

Minimum

______ 1.37X10' 9

__ _ .682X10' 9

_ _ _ 7.44X10' 9

______ 7.69X10'9

 _ 7.92X10-9

 _ .381

 _ .086

______ 8.38xlO- 18

______ 2.03X10-18

 .528xlO- 18

______ .419

__ __ .103

______ .026

2.51x10-"

.672x10-"

7.92x10-"

7.98x10-"

8.02 xlO-9

.317

.209

.083

5.09xlO- 18

.401 xlO- 18

.254

.117

.020

.093

4 99xlO~20

2.0x10-"

2.5xlO- 3

ACO

2 56X10"20

2 Ox 10"17

'From Larson and Buswell (1942, p. 1667). 

2FromHsu (1964).

draining waters and by more than 10 in adamellitederived waters. Cottonwood Spring and Poison Creek 

Spring are also much closer to dolomite saturation than 

are their counterparts in the pluton, but all waters are 

even more undersaturated with respect to dolomite 

than to calcite.

The undersaturation of calcium carbonate in the 

Crooked Creek and Cottonwood drainage basins contrasts with the fourfold supersaturation reported by 

Barnes (1965, p. 92) in the headwater springs of Birch 

Creek, just south of the study area. The latter drains a 

mixed terrane in which solution of Wyman limestones, 

as well as the Reed Dolomite, may have a profound 

influence on the state of the ground-water calcite reaction.

Partial pressures of carbon dioxide in the four spring 

waters (table 24) were computed from the following 

relation:

PCO2 (aq)=. (H+KHCQs-)

where

and

(H+XHCQs-) 

(H2C03 )

(H2C03 ) 

PCO2

All calculated values for the waters are at least twice 

that of the atmosphere, and Cottonwood Spring shows 

CO2 partial pressures as much as 22 times greater than 

the air. The two springs related to the dolomite terrain 

have partial pressures much greater than the springs in

TABLE 24. Partial pressures of carbon dioxide in four spring waters 

and a comparison with atmospheric PCO%

[M.P. = most probable value]

Cottonwood Poison Creek Crooked Creek Sage Hen 

Spring Spring Spring Spring

PCQj of water (atm):

M.P. _________ _ ___

PCC^of 

atmosphere _ atm .__ 

PCQj(w)/PCO2 (a):

M.P. _____ _

5.05 xlO- 3

2.66X10- 3

2.3xlO- 4 

22

12

6.3

2.86X10'3

2.3xlO- 4 

18

12

8.6

5.70x10-" 9.79x10-"

2.3x10-" 2.3x10-"

2.5 4.2

the adamellite, yet the pH of all springs is similar. 

Solution of dolomite would tend to increase PCO2 but 

would also increase pH, the net effect being to decrease 

free CO2 . The explanation for the striking contrast between the two groups of springs must partly lie in the 

marked vegetational differences between the two 

lithologies: The adamellites are dominated by relatively dense growth of sagebrush, limber pine, grasses, 

and perennials, whereas bristlecone pine and sparse 

low perennials cover most of the Reed terrane. Perhaps 

photosynthetic rates, and hence root respiration, differ 

greatly between the two plant communities. In any 

event, it is apparent that local vegetational changes 

may play an important role in controlling the pH of 

ground water and hence in regulating rates of chemical 

degradation.

For the adamellite-draining springs and adamellite 

soil water, means and standard deviations were used to 

compute molalities and activities for Na-f, K+, H+, 

and HiSiC^ and to plot the range of each fluid on lowtemperature stability diagrams for Na silicates (fig. 

307) and K silicates (fig. 308). Plots based on activities 

did not differ significantly from those based on molality 

and are not reproduced on the diagrams. Sage Hen Flat 

pluton water plots within the kaolinite field in both 

figures, as do most stream and spring waters. The position of the water plots, toward the silica-rich side of the 

kaolinite field and away from the gibbsite field, tends to 

support the X-ray diffraction and microprobe evidence 

that kaolinite is forming as a stable authigenic phase in 

the adamellite soils. The waters are well above quartz 

saturation, probably owing to the weathering of Si from 

feldspars, biotite, and other silicates, in addition to 

quartz, but are significantly below saturation with 

amorphous silica.

Major departures from equilibrium are evidenced in 

adamellite-related waters by oversaturation with respect to quartz and undersaturation with respect to 

colloidal silica and in waters draining the Reed by undersaturation with regard to dolomite. Such departures, however, do not preclude the existence of steadystate conditions in the spring waters.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 411

8

Gibbsite

Means:

X Soil water extracts 

 Crooked Creek Spring 

A Sage Hen Spring

Ranges: []

-6 -5

Log [H 4 SiO4

FIGURE 307. Stability relations of phases in the system Na2O-Al2 O3-Si02-H2 O at 25°C and 1 

atmosphere total pressure as functions of (Na+)/(H+) and (H4SiO4 ). After Feth, Roberson, 

and Polzer (1964, p. 65).

RELATION OF SOIL WATER TO PRECIPITATION AND SPRING WATERS

An important question in the chemistry of natural 

waters is the space-time dimension of chemical weathering changes. Do most of the chemical additions to rain 

and snow water occur quickly within the soil, or does the

Potassium mica '\ Potassium feldspar

Gibbsite

Means:

X Soil water extracts 

 Crooked Creek Spring 

A Sage Hen Spring

Ranges: []

Kaolinite

-6 -5

Log [H 4 SiOj

FIGURE 308. Stability relations of phases in the system K2 O-Al2 O3 -SiQ2-H2 O at 25°C and 1 

atmosphere total pressure as functions of (K + )/(H+l and (H,SiO4 ). After Garrels and 

Christ (1965, p. 361).

composition of percolating ground waters continue to 

change, even if the lithology remains the same? Although absolute concentrations of chemical species in 

the soil water extracts are much higher than those in 

precipitation and spring water, comparisons are possible through ratios of dissolved constituents.
412 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

Figure 309 compares the composition of waters related to the Reed Dolomite in the ternary system 

Na + K - Ca- Mg. 6 The dolomite soil water extracts 

are more or less intermediate in composition between 

precipitation and spring water values, but somewhat 

higher in percentage Ca than either of the other fluids. 

A progressive increase in the divalent/monovalent cation ratio occurs from precipitation to soil water to 

springs. The Ca/Mg ratio increases slightly from about 

1.8 in precipitation to a value of nearly 5 (the ratio in 

bedrock is about 1.6) in soil water, but then decreases 

substantially from soil water to spring water. This decrease may be in response not only to bedrock composition, but to selective adsorption and removal of Ca by 

the soil exchange complex. The fact that the spring 

waters do not plot closer to the bedrock is probably 

attributable to the weathering of ash and local soil 

contaminants and to differing relative mobilities of the 

plotted cations.

Waters related to the adamellite are compared for the 

same ternary system in figure 310 (bottom). Soil water 

plots over a wide range and shows a definite increase in 

Ca/Na + K and Ca/Mg with respect to both precipitation and bedrock. It appears to be closer in composition 

to spring water than precipitation in terms of Ca concentration. The hydrolysis of plagioclase, solution of 

secondary calcium carbonate in the soil, and the high 

mobility of Ca is probably responsible for this trend, 

which proceeds away from bedrock composition. Also in 

figure 310 (top), it appears that the Na/K ratio in the 

soil water extracts has decreased relative to precipitation in response to bedrock and perhaps ash composition. The large increase in Na/K from soil water to

10.0

EXPLANATION

+ Precipitation mean o Bedrock mean 

 Soil water mean E Volcanic glass 

XctCottonwood Spring mean ^^ Distribution 

A Exchangeable cations mean

FiGURt 309. Progressive cation changes from precipitation water to soil and spring waters 

related to Reed Dolomite. Plots of bedrock, volcanic glass, and exchangeable cations 

suggest relative influence of these factors.

10.0 

Ca/Mg

40 60

"Values plotted on compositional diagrams in this paper were calculated on a parts per 

million (milligrams per liter) rather than an equivalents per million basis because the 

oxidation states of Fe and Mn were not known and a uniform basis between diagrams was 

desired.

EXPLANATION

+ Precipitation mean A Exchangeable cations mean

 Soil water mean o Bedrock mean

xc Crooked Creek Spring mean E Volcanic glass

x s Sage Hen Spring mean ^i Distribution

FIGURE 310. Progressive cation changes from precipitation water to soil and spring waters 

related to adamellite.

ground water is interpreted as the result of K fixation by 

colloidal adsorption and selective plant uptake, and of 

high Na mobility. Soil water has a Na/K ratio much 

closer to precipitation than to spring water, but is quite 

distinct from both.

Figure 311 shows regular increases in both Mg/Fe 

and Ca/Fe from precipitation to soil water to spring 

water, with soil water plotting approximately intermediate in position between the other two fluids. Both 

trends are away from bedrock composition and apparently result from low Fe mobility due to precipitation of 

Fe oxides within the soil.

From precipitation water to soil water to ground 

water, increases are evident in Si relative to Na+ K and 

Mg^Fe (fig. 312), presumably in response to bedrock 

composition and possibly also to the rhyolitic ash. Soil 

water extracts on this diagram plot much closer to precipitation than to spring waters.

The pH value is probably the best single indicator of 

water chemistry. The median pH of snow samples from 

the Sierra Nevada is reported as 5.8, close to the value 

for pure water in equilibrium with atmospheric carbon 

dioxide (Feth, Rogers, Roberson, 1964, p. 24-25). All soil 

and ground waters in the White Mountains have much
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 413

100

wivr

EXPLANATION

Precipitation mean 

WM=White Mountains 

SN =Sierra Nevada

Soil water mean

Sage Hen Spring mean

Crooked Creek Spring mean

Bedrock mean

Volcanic glass

Distribution

0.01 0.1 1.0

Ca/Fe

FIGURE 311. Mg/Fe and Ca/Fe ratio comparisons of waters related to adamellite.

: EXPLANATION

+ Precipitation mean

WM=White Mountains 

SN =Sierra Nevada 

Soil water mean

"s Sage Hen Spring mean

*c Crooked Creek Spring mean

o Bedrock mean

3 Volcanic glass

O Distribution

0.01

0.01 100

Si

Mg+ Fe 

FIGURE 312. Silica-cation ratio comparisons of adamellite-related waters.

higher pH's (tables 18, 20, 21) than this figure, owing 

principally to solution and hydrolysis reactions. For the 

dolomites, soil saturation pH is comparable to spring 

water pH, but for the adamellite, soil saturation values 

are intermediate between the pH of precipitation and 

that of the springs.

Most of the chemical trends just described appear to 

be controlled by bedrock composition or relative mobility, but the ground waters plot in tight groups distinct 

from the bedrock, suggesting that a steady-state condition, rather than chemical equilibrium, exists in spring 

waters that have passed through both lithologies. In the 

soils, absence of both equilibrium and steady state is 

manifested by the scatter of soil water points on the 

compositional diagrams.

Soil water extracts from both dolomite and adamellite terrain are notably distinct in composition from 

precipitation and spring waters draining the respective 

lithologies. Total concentrations are much greater in 

soil saturation extracts than in spring waters owing to

the diluting effects of percolating precipitation water on 

the latter. The contrasting ionic composition of these 

two groups of fluids imply the existence of weathering 

reactions at considerable depth and preferential channeling of ground-water flow from certain localized areas 

of high recharge and possibly of different lithology. 

Most of the soil water extracts plot in an intermediate 

position between precipitation and ground water, but 

some (Na/K for adamellite-related water, for example) 

soil water plots do not fall in a position between the 

other two fluids. The pH of dolomite soil water extracts 

is much closer to spring water than to precipitation, 

however, suggesting that chemical adjustments in systems having soluble phases occur more rapidly than in 

those involving silicate or oxide phases.

Precipitation of calcium carbonate, probably sporadic 

in response to wet and dry seasons, and the contaminating influence of the rhyolitic ash, local aeolian debris, 

and foreign waters complicate the interpretation of soil 

water compositions. Also, the preceding conclusions assume that saturation extracts approximate actual soil 

water, an assumption which may not be entirely valid. 

A longer period of water contact with the soil might be 

expected to shift soil water composition closer to that of 

spring waters and to decrease the variability of extract 

compositions. A need exists for methods of soil water 

extraction which will produce fluids clearly representative of the actual soil solution under field conditions.

CHEMICAL FRACTIONATION IN THE 

BEDROCK-SOIL-WATER-PLANT SYSTEM

Elements released by solution or hydrolysis of mineral grains follow a variety of courses. They may dissolve in the soil water and be flushed out of the system, 

precipitate as a solid soil phase, become adsorbed on 

colloidal soil particles, or be utilized by organisms, 

especially vegetation. Chemical analyses of representative plants from the area, together with data already 

presented, make possible the location and apportionment of a number of chemical species within the 

bedrock-soil-water-plant systems of the Reed Dolomite 

and the adamellite of Sage Hen Flat.

Soil water and exchangeable cation concentrations 

were converted from milliequivalents per 100 g of soil to 

grams per cubic centimeter of soil, using milliequivalent weights and mean bulk densities of the total soil. 

Since the laboratory data apply to only the 

less-than-2-mm fraction, two sets of figures were calculated for the soil water, one assuming no contributions 

from the soil gravel fraction (minimum) and a second 

assuming a contribution from the coarse material proportional to its weight percentage of the whole soil 

(maximum).

For practical reasons, only a few of the hundreds of
414 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

White Mountains plant species could be analyzed. 

Aboveground parts of sagebrush (Artemisia arbuscula), 

junegrass (Koeleria cristata), and sandwort (Arenaria 

kingii), and twigs, needles, and cones of bristlecone pine 

(Pinus aristata) and limber pine (P. flexilis) were collected on both dolomite and adamellite. Aboveground 

parts of flax (Linum perenne} were obtained from dolomite terrain. These six species were chosen to represent 

vegetational groups as follows: Pinus aristata and P. 

flexilis trees; Artemisia arbuscula sagebrush and 

shrubs; Koeleria cristata grasses; Arenaria kingiinoncarbonate-associated herbs; and Linum 

perenne carbonate-associated herbs. Plant samples 

were washed with distilled water and ovendried at 

104°C prior to ash analysis (table 25; see section "Supplemental Information" for analytical procedures.)

Percentage cover for the preceding groups, estimated 

at about 20 randomly selected sites on each lithology 

and then averaged for dolomite and for adamellite, is 

given in column 12 of table 25. These figures are recalculated to 100 percent in the last column. The percentages of total vegetation (in terms of cover) were then 

used to obtain weighted averages for each element in 

plants on each substrate, as follows:

Weighted average Si=(percent Si in species x) (percent x in total vegetation) + 

(percent Si in species y) (percent 

y in total vegetation) + . . . + 

(percent Si in species AT) (percent 

N in total vegetation),

where AT is the total number of species considered. Vegetational concentrations from table 25 were adjusted to a 

grams per cubic centimeter basis using the weight and 

percent cover of each plant sampled (giving grams per 

square centimeter) and dividing by the mean depth of 

each soil type (giving grams per cubic centimeter of

soil). Calculations were made for the individual species 

and for the weighted averages applicable to each soil 

type. Since these averages assume continuous vegetative cover, a second pair of weighted averages were 

computed, adjusting for the actual plant cover. Plots of 

total soil (uncorrected for contamination), exchangeable cation, soil water, and plant concentrations for 

adamellite and dolomite terrane are shown in figure 

313. The adamellite comparisons, expressed on a percentage basis, are extended to precipitation, bedrock, 

and spring waters in figure 314. Vegetational concentrations are computed as percentage of soil water plus 

plant concentration in table 26.

An examination of element totals in figure 313 indicates that constituents released by weathering are concentrated primarily in exchangeable positions (cations 

only) and secondarily in soil water and plants. Exchangeable cations are adsorbed in the sequence 

Ca > Mg > K > Na. Cation exchange in soils therefore 

tends to decrease the Ca/Mg and K/Na ratios with respect to ratios of cations initially made available by 

weathering. Cation exchange is less important as a 

fractionation mechanism than these illustrations 

would imply, because after the exchange complex becomes saturated, no further removal by exchange can 

occur unless the exchange capacity increases.

Although trends vary to some extent between species, 

the overall tendency of the White Mountains flora, with 

respect to soil water (table 26), is to withdraw elements 

in the sequence P > Fe » K > Ca = Mg > Si» Na. The 

ratio of plant concentration to soil water concentration 

is less for the dolomite, but the sequence is the same 

regardless of lithology. As the result of plant uptake, 

the soil K/Na ratio is further decreased, and Fe and P 

are extracted in relatively large quantities. Si is 

sufficiently soluble at the moderate to high pH's of the 

adamellite and dolomite soils to become concentrated in 

the liquid phase, although plant concentrations constiTABLE 25. Chemical composition (dry weight percentage basis) of some major plant species on Reed Dolomite and 

adamellite of Sage Hen Flat and weighted averages used for geochemical comparisons

Al Fe Mn Mg Ca Na

Number of Number of Mean percent Percent of total

plants duplicate cover vegetation

P analyses (see text) (see text)

Dolomite:

Adamellite:

Weighted average

_ _ ___ _ 0.0080

_____ __ _ .0300

_____________ .0980

_ __ __ _ .0760

____________ .0549

________ _ - .0282

__ _ _ _ .0120

__ ___ __ .0120

_____________ .0600

_ _ __ __ .0300

_____________ .1200

__ ___ _ __ .0665

.071

.60

.82

1.1

. .42

.29

.051

.034

1.07

.47

5.5

2.18

013

.10

.108

.010

.0068

.147

.064

.43

.20

0.0016

.0165

.0100

.0049

.0049

.0044

.0131

.0064

.0267

.0148

0.17

09

.23

.26

.47

.26

.21

.08

.08

.13

.09

.33

.18

0.58

.57

.71

.81

3.39

.85

.88

.55

.44

.57

.34

2.52

1.10

0.0053

.0133

.0081

.0066

.0219

.0034

.0072

.0078

.0083

.0118

.0058

.0353

.0172

0.20

.23

.77

.27

.69

.82

.33

.31

.45

.80

.27

.92

.68

0.0480

.0630

.0874

.0560

.0530

.0745

.0539 ___.

.0690

.1100

.0829

.0385

.0555

.0666 ___.

2

3

3

4

6

1

1

4

2

2

1

1

3

1

1

1

1

1

4

1

1

17.60

.77

1.45

2.74

2.43

2.11

(27.10)

.05

2.61

9.85

6.47

8.32

(27.30)

64.9

2.8

5.4

10.1

9.0

7.8

(100.0)

.2

9.6

36.0

23.7

30.5

(100.0)
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 415

L/

10-1

10"2

TO"3

_J

5

w

LL

0

rr 10"4 iniHJ

§ 

H 

Z

LU

CJ

CJ

CD 10~5

D

CJ

rr

LU

Q_

w

<

rr 

O 10"6

10'7

10"8

10"9

i i i i i i l i

A

A

-

A A

A

A

-

A

X

X

-

A

X X

.Ak

.Ak g,

Ak. pfl 

v a 'Aa Pa X f Pf .

 © w

pf l r 8! .W-C 

"Aa .Ak tpa

53 W-C

, * *KV

4 » Bf .w .Pf X jTw .w-c » w 

 Ak f |Aa 'Aa

^Aa Pa* Aa.

.w-c Ak* 

Ak.

.Kc

.Pf .Kc 

w |W-c .w-c 

Pf «Aa Pa .Pa

Pa* . »pf Kc

PxC

.w-c ja

Kc.

-

o

c

0)

1 1

_ c

W

1 1 1 1 1 1 1 1

1 1 1 1 1 1

A

A

A

x

X A

A

A

X

X

Bf 

X .Ak -

. AK -ty

4" .Aa 

w.

8! w AUJAa Pa*

Pf* pa Ak]g

4- .Aa w-c "f_ * KC

w. *Pa 

*Pa *Kc

'Pf .Pf .

.Kc .w-c pa *

.w-c *Kc *w 

.L

.L

.Ak 

Pf l .Kc

* *w-c

.Aa

w, .Aa

Pa Ak'

.L

.w-c

*Kc

-

L ~5

o

^

c

1

8f 3

^" LL

1 1 1 1 1 1

Na Si Ca Mg K Fe p f Na Mg Ca K P |

ADAMELLITE OF SAGE HEN FLAT REED DOLOMITE

EXPLANATION

4 Soil water minimum Aa Artcmisia arbuscula Pf Pinus flexilis

Bi Soil water maximum Ak Arenaria kingii w Weighted average

X Exchangeable Kc Koeleria cristata w-c Weighted average

A Soil (<2mm) L Linum perenne (adjusted for ac-

. Plants: Pa Pinus aristata tual cover)

FIGL RF 313. Comparison of elemental and total concentrations in soil, soil water, colloidal exchange, and plants, expressed in terms of grams per cubic centimeter of soil.
*» OF PERCENTAGE NINE-ELEMENT TOTAL 

S <* Po

-.00 _» 

EROSION AND SEDIMENTATIO

X

A

0

O Q

I X 

<» 

+

A 

A + A 

D o ®

n A ®

o

~r

A

D 

X

+

g

o 

0 A -

o 

.0.000 iQ.OO

... i i i i i i t i T

N IN A SEMIARID ENVIRONMENT

TABLE 26 Fractionation by plants with respect to soil water for seven 

elements in adamellite and dolomite terranes

Plant concentration (g/cc soil)

[Elemental percentage = p^ concentration + soil water concentration (g/cc soil) * 100]

Si Ca Mg Na

Adamellite: 

Continuous cover __ 25-30 46-53 47-54 5.9 -7.4 

Actual cover __ _ 8.3-11 19-23 19-24 1.7-2.1

Dolomite: 

Continuous cover _ __ 17-30 17-30 1.1-2.3

Actual cover 5.1-10.0 5.2-10.2 0.31-0.65

K Fe P Total

Adamellite: 

Continuous cover _ 51-58 98 -100 47-54 

Actual cover _ ____ 22-27 92 99 20-24

Dolomite: 

Continuous cover ___ 34-51 __ 100 18-32 

Actual cover - _ 12-22 99 100 5.7-11

The actual extent to which vegetational fractionation 

occurs is of course dependent on the rate of plant uptake 

with respect to the rate of leaching. It has been demonstrated (Marchand, 1971) that chemical denudation by 

plant uptake and litter erosion in this area, although of 

much less significance than leaching in terms of total 

chemical removal, may be of considerable importance in 

the extraction of certain elements, especially metals 

such as Al, Fe, and Mn. It should also be remembered 

that elemental concentrations in vegetation represent 

large static quantities which are unavailable to leaching and which are potentially removable by sporadic 

accelerated erosion owing to fires or flooding, as well as 

by normal seasonal denudation.

SUMMARY AND DISCUSSION

The influences of erosion, deposition, vegetation, and 

microbial activity combine to further complicate an alreadv complex series of chemical and physical alteraNa K Ca Mg Si Fe Mn Al 

ADAMELLITE OF SAGE HEN FLAT

EXPLANATION

A Mean bedrock + Precipitation 

A #94 bedrock -fr Soil water 

D #94 soil <2mm, corrected o Sage Hen Spring

for contamination Crooked Creek Spring 

X Exchangeable cations ® Vegetation

FIGURE 314. Fractionation of nine elements in the adamellite bedrock-soil-water-plant 

system based on percentage concentrations.

tute as much as 30 percent of the nonexchangeable total 

for areas of continuous vegetative cover. Fe and P tend 

to be quite insoluble under these oxidizing and alkaline 

soil conditions.

tions (fig. 269) in the weathering processes by which 

unstable minerals are converted to stable forms under 

the prevailing surficial conditions, which may themselves change with time. A complete analysis of all 

aspects of the weathering process is beyond the scope of 

this paper (the influences of microorganisms, for example, is not evaluated), but the data of the preceding 

pages suggest the direction and approximate magnitude of some physical, mineralogical, and chemical 

changes resulting from the weathering of dolomite and 

biotite adamellite in a present-day semiarid, subalpine 

climate. These changes involve alterations not only in 

the solid phases, but in the associated liquid and gas 

phases as well. Elements released by weathering are 

fractionated through the effects of plants, colloidal exchange, and leaching.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 417

WEATHERING OF REED DOLOMITE

Field observations and size analyses of soils and bedrock indicate that the initial step of dolomite weathering in the White Mountains involves both physical and 

chemical breakdown of angular blocks produced by 

jointing. Polycrystalline soil grains, commonly bounded 

by cleavages, slowly accumulate from freeze-and-thaw 

disintegration of these blocks, except in areas of recrystallization near plutonic bodies; here postthermal contraction may have created intergranular stresses, leading to accelerated weathering and spheroidal forms. 

Chemical weathering is evident throughout the process 

of grain diminution, but appears to exert a greater effect 

in the interval between bedrock and soil gravel than 

between soil gravel and less-than-2-mm soil. 

Mineralogical decomposition, occurring in the sequence 

dolomite» tremolite, epidote > talc, K-feldspar, 

plagioclase, biotite 5* apatite > quartz and ilmenite 

(fig. 294), resulted in percentage chemical losses, from

? 

bedrock to soil, of Mg > Ca > Sr > Mn^ Fe (fig. 301).

Pure calcite, apparently precipitated during periods of 

desiccation and partially dissolved during seasonal 

influx of meteoric waters, occurs as the single verifiably 

authigenic soil phase, in rinds on spheroidally weathering boulders, on surfaces of soil fragments, and as a 

discontinuous calcium carbonate soil crust.

Relative mobilities of spring waters with respect to 

the dolomite bedrock yield the sequence Mg > Ca » 

Fe > Mn (table 22). These findings agree with losses 

from bedrock to soil, except that they show Fe to be more 

easily mobilized from dolomite than Mn. Dolomite soil 

water extracts differ notably in composition from both 

spring and precipitation waters, probably owing in part 

to secondary calcite, ash fragments, and local contaminants in the soils. The soil water extracts have pH's 

much closer to the spring waters than to rain or snow, 

suggesting a fairly rapid adjustment to soil composition 

in these soluble soils. Comparisons of ion-activity products with solubility constants indicate that waters 

draining the terrane are undersaturated with respect to 

both calcite and dolomite.

Calculated carbon dioxide partial pressures for dolomite-derived waters exceed atmospheric values by more 

than an order of magnitude and those of waters from the 

adamellites by several times. The excesses above atmospheric PCO2 are presumably created by a combination of root respiration, humus oxidation, and other 

organic processes; the greater PCO2 values in the dolomite waters must primarily reflect the change in vegetation with substrate, not solution of carbonate.

WEATHERING OF ADAMELLITE OF SAGE HEN FLAT

Weathering in the Sage Hen pluton occurs in several 

stages. Physical disintegration proceeds by frost riving

along intergranular weaknesses caused by cooling and 

contraction of the rock or possibly by swelling of biotite 

during initial weathering. Boulders exfoliate and grus 

accumulates in the AH soil horizon. This coarse material is largely unaltered chemically or mineralogically 

except for minor Fe oxidation; the principal chemical 

attack occurs during the transformation of grus to finer 

sized particles. Primary minerals weather in the sequence plagioclase (An25_30 ) > hornblende > biotite, 

epidote > microcline, plagioclase (Anio-is), allanite > 

apatite, chlorite, magnetite > sphene, quartz, muscovite, ilmenite > zircon (fig. 297), resulting in percentage chemical losses, from fresh rock to soil, in the

?

sequence Rb > Na= K^ Mg > Sr > Mn^ Ca > Ba > 

Si > Al » Fe > Ti (fig. 301). X-ray diffractometer and 

electron microprobe results suggest that kaolinite, and 

possibly small amounts of vermiculite and montmorillonite, are forming as authigenic alteration products of 

feldspars, biotite, and other silicates. Microprobe

?

analyses of biotite indicate losses in the sequence Ba > 

K > Mg > Fe > Si > Al (table 8); cations in eightfold to 

twelvefold coordination appear to be lost most readily, 

followed by octahedral cations, and finally elements in 

sixfold and fourfold coordination. Microcline shows 

some losses of both Na and K, and plagioclase (An10_3o) 

shows changes that imply removal in the sequence 

Na > Ca > Si > Al (table 10; fig. 300).

Relative mobilities of chemical species in adamellite 

spring waters indicate that changes with regard to bedrock occur in the sequence Ca > Mg ^ Na » Six K^ 

Mns Fe > Al (fig. 306). Although this order shows 

some agreement with bedrock-to-soil losses, it is not 

entirely consistent with conclusions based on the solid 

phases alone. The low K mobility is probably the result 

of plant extraction and fixation within the soil. Plant 

uptake and litter erosion may explain the low Al content of spring waters. It is suggested that Mg and especially Ca are augmented in waters draining the pluton 

owing to the solution of fine-grained carbonate particles 

continually blown into the adamellite terrane. If this 

latter hypothesis is correct, the chemistry of ground 

waters is extremely sensitive to the presence of small 

quantities of soluble materials, including those foreign 

to the area. The fact that waters from two springs draining the adamellite can be chemically distinguished is 

another indication of such sensitivity. Both soil and 

spring waters associated with the pluton plot within the 

kaolinite stability field (figs. 307, 308) and are supersaturated with quartz but undersaturated with respect 

to colloidal silica. Proportions of solutes in adamellite 

soil water extracts appear to be roughly intermediate 

between precipitation and spring water in the adamellite terrane.
418 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

GENERAL WEATHERING RELATIONSHIPS

Observations in the White Mountains, as well as in 

warmer and wetter regions, suggest that physical 

weathering of a given lithology may be chiefly a function of the nature and spacing of initial physical weaknesses, particularly intergranular openings, cleavages, 

fissility, and planar weaknesses, especially joints, 

which may serve as avenues for fluids. The process of 

physical breakdown, which tends to precede chemical 

weathering, may be as closely related to lithologic features as to external conditions. Thermal history or inherent properties such as grain size, grain adhesion or 

cohesion, crystallographic properties of mineral constituents, bedding characteristics, or jointing may be 

more critical in affecting rates of physical weathering 

than climate.

Chemical weathering of any mineral is a function of 

the chemical composition and crystalline structure of 

the mineral and of the chemical environment in which 

weathering occurs. Ca, Mg, Fe, Mn, and Sr, for example, 

are all lost more readily from dolomite than from silicates and oxides in the adamellite. Dolomite-to-soil percentage losses of Fe are about the same as for Mn, but 

adamellite Mn losses are much greater than those of Fe. 

In nonsoluble lithologies such as the adamellite of Sage 

Hen Flat, chemical losses tend to adhere to the general 

pattern of alkali metals > alkaline earth metals > 

nonmetals > metals.

Precipitation water undergoes major chemical 

changes upon entering the soil, but significant additional modifications occur during percolation to springs. 

The state of both soil and spring waters with respect to 

calcite, dolomite, and silica saturation preclude chemical equilibrium in the natural waters studied. This result is not surprising since chemical weathering, which 

supplies most of the constituents to the waters, is itself 

an open-system disequilibrium process. It is noteworthy, however, that although steady-state conditions 

are definitely not attained in soil waters, spring waters 

closely approximate constant composition. Contact 

with weathering materials over a considerable spacetime interval is apparently necessary for the achievement of a steady state, but this interval may be decreased somewhat in the case of mobile constituents in 

readily weatherable minerals. The existence of steadystate spring water compositions indicates another area 

of applicability of the "dynamic equilibrium" concept 

suggested by Hack (1960) and others in regard to 

surficial processes.

Elements removed from lattice sites in primary minerals undergo fractionation by (1) formation of secondary phases primarily clay minerals, calcium carbonate, and various insoluble precipitates, (2) adsorption 

on colloidal mineral or organic particles, (3) plant uptake, and (4) solution. Quantitative information concerning fractionation of elements into secondary phases 

is not available for the two lithologies studied here (Al, 

Si, Fe, Mn, P, and Ca probably undergo fixation to some 

extent, in this form), but nine principal elements appear 

to apportion themselves between vegetation, colloidal 

exchange, and solution as follows (figs. 313, 314; table 

25):

Na,

Si,

Ca,

Mg,

K,

Fe, Mn, P,

Al,

soln » exch > veg 

soln » veg 

exch > soln > veg

?

exch > soln == veg 

veg » soln > exch 

veg » soln 

veg >» soln

Constituents entering authigenic phases or exchangeable positions are retained within the soil and 

are removed only through soil erosion or change in 

chemical environment. Elements taken up by plants 

are recycled through the soil to the extent that decomposition takes precedence over litter erosion. Evidence 

presented elsewhere (Marchand, 1971) suggests that, in 

this area at least, most elements are eventually dissolved and carried out of the soil by deep percolation. 

Results from the preceding study indicate that removal 

by plant uptake and litter erosion, although probably 

not significant in terms of total chemical denudation, 

may play some part in the total extraction of P and K 

from the bedrock and soil and undoubtedly accounts for 

appreciable parts of the chemical denudation of Al, Fe, 

and Mn. Another effect of vegetation in the weathering 

process may lie in the conversion of relatively insoluble 

constituents to more soluble chemical forms in which 

they could be carried out of the system. Plant uptake, 

litter fall, and decomposition may thus facilitate leaching, but data are lacking to evaluate the quantitative 

importance of this aspect of the geochemical cycle.

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WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 419

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420 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

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P-
SUPPLEMENTAL INFORMATION
422 EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT

METHODS, REPRODUCIBILITY, AND ACCURACY

Field procedures for the collection of data and samples have been 

discussed in the text. Several temporary field impregnations were 

obtained from soil pits with Quickmont (available from E. V. Roberts 

and Associates, Culver City, Calif.) and later fully impregnated under 

vacuum with leucite. The advantage of the field impregnation is that 

natural orientation and textures are maintained. Bedrock and soil 

samples were treated in the laboratory as outlined in figures 315 and 

316. 7

Fresh bedrock chips and soil samples (soil gravel, less than 2 mm) 

were crushed with a tungsten carbide mortar and pestle and ground to 

-50 mesh in a tungsten carbide ball mill. Each fraction was then split 

and made into an X-ray fluorescence pellet. The values of table 27 

(top), representing chips of the same sample, ground in different 

mortars and separately prepared, indicate no significant source of 

error in the grinding, splitting, or pellet-making operations. The 

replicate analyses of the table suggest precision of about ± 0-6 percent 

of the analyzed value and generally below 2 percent for values above 

2.0 percent. Table 28 compares X-ray fluorescence results with those 

of wet chemistry (unpub. data of Ken-ichiro Aoki) and those for Na 

and K by flame photometer (by Joaquin Hampel; see "Introduction"). 

Agreement is good in some cases and very poor in others. Lighter 

elements such as Na, Mg, Al, and Si are not as easily excited by X-rays 

as heavier elements and are most susceptible to error. Where samples 

approximate the composition of well-analyzed standards, however, 

X-ray results appear to be both precise and accurate. The values of

BEDROCK SAMPLE 

Removal of weathered portions (rock saw)

Crushed.ground

(Tungsten carbide, agate

mortars, <50 mesh)

Sieved

(50-230 mesh)

Separated X-ray

(two heavy liquids) fluorescence

 . ' pellets Gram mounts i

(line counted) T

| Chemical

Mmeralogic analyses (adamel- analyses 

lite: accessory minerals; dolomite: all minerals

1

(Adamellite only)

Thin sections 

i

Staining potassium

feldspar 

I

Point counting

i

Mineralogic analyses 

(quartz, potassium 

feldspar, plagioclase.

biotite)

Grains for microprobe, immersion oils.U stage

7The following parameters were determined for the less-than-2-mm fraction of many soil 

samples for purposes outside the scope of this paper: Phosphorus in 10:1 water extracts, 

permanent wilting point (soil moisture at 15-atm tension), moisture equivalent (soil moisture 

at 1 /3-atm tension), available water (mositure equivalent minus permanent wilting point), 

percentage carbonate, and total carbon.

SOIL

FIGURE 315. Flowsheet for laboratory treatment of bedrock samples.

Hampel were used for Na and K, but all other figures were taken from 

X-ray determinations (except values of Aoki used as X-ray standards). 

Thin sections of five adamellite bedrock samples were stained for 

K-feldspar (Rosenblum, 1956) and point counted to determine quartz, 

K-feldspar, plagioclase, and biotite percentages. Mineralogical 

analyses of crushed bedrock (50-230 mesh) and less-than-2-mm-sand 

(greater than 62 #m, crushed to -50 mesh), fine sand and very fine 

sand fractions of soils were obtained from line counts of grain mounts 

after removal of organic matter with 2 percent hydrogen peroxide 

(soils only) and two successive heavy liquid separations. For the 

dolomite samples, liquids of specific gravity 2.69 (bromoform plus 

alcohol) and 2.95 (tetrabromoethane) were used; liquids having densities of 2.88 (bromoform) and 3.3 (methylene iodide) were used for 

adamellite samples. A minimum of 900 grains, and usually more than 

SAMPLE

f~

Impregna 

thin secti

Crushed, grc 

sten car 

mortars,

Sie

>2r 

X1 

ted Sieved (<2mm) 

on |

1 1 

Jund (tung- NH4 Ac Saturation 10:1 extraction Furnace Remo 

bide, agate extraction paste (water) Oxidation organic 

<50mesh) 1 ^ x (H 2

Extractable cations p Total C

i t

pH Water-soluble 

cations

ved Sie

1 + i

val of Sieve and pipette 1/3-atmosphere 15-atmosphere 

matter analyses moisture moisture 

02 > | 

Size 

distribution ,

Percentage 

carbonate

ved

 H 202 | 

im <2nm <62#m >62^um Fine sand Very fine sand 2-62 jum

ay fluorescence pellets Two heavy-liquid separations, grain mounts, line counting Quantitative X-ray 

1 1 1 1 1 diffraction

Total chemical analyses Mineralogical analyses

Grains for microprobe analyses, oil immersion, U stage 

FIGURE 316. Flowsheet for laboratory treatment of soil samples.
WEATHERING, SOILS, GEOCHEMICAL FRACTIONATION, WHITE MOUNTAINS, CALIFORNIA 423

TABLE 27. Reproducibility of X-ray fluorescence analyses

[Values yielded by opposite sides of the same pellet, except sample 58]

Fe Mn Ca Sr Rb

(weight percent) (ppm)

58 (agate) _________ 0.22 0.06

58 (tungsten carbide)__ .22 .06

47 soil . _ __ __ 3.26

47 soil _________ 3.26 _ _

52 soil _______ _

52 soil __________ _____ ____.

64 soil __________ _____

64 soil __________ _____ _______

66 soil __________ _____ _____

66 soil ___ _____ _______

68 soil _________ _ ___ _ _ _

68 soil __________ _______

97 ________________ 1.32 _ _

97 ________________ 1.32

98 ____________________ ________ .042

98 __________________ ______ .045

21.86

21.99

59.3 0.0 

59.5 .0

22.98

23.31

22.76

23.00

43.1

44.1

166

167

1,500 grains, per sample was counted. The statistical analysis of 

Brewer (1964, p. 46-50) indicates that counts of 1,500 grains yield 

results within about 5 percent probable error for major constituents 

and less than 15 percent for minor minerals. Mineral densities used to 

compute weight percentages from grain mounts were obtained by 

direct measurement or from chemical composition information.

Line-counted samples were used as standards for quantitative 

X-ray diffraction analyses of silt fractions. Both standards and samples were finely ground in a mortar, mounted on glass slides with the 

aid of acetone, and X-rayed under identical conditions on the same 

day. Abundances were based on peak heights above background. 

Glass was assumed to make up the difference between totals and 100 

percent, an assumption verified by many visual estimations of siltglass percentage under the polarizing microscope. Probable error is 

estimated at less than 15 percent of the given value.

Laboratory soil pH measurements were made with a Beckman 

Zeromatic pH meter on water-saturation pastes. Replicate analyses of 

samples yielded results within 0.1 pH unit. Similar pastes were extracted by the Buchner funnel method of Bower and Wilcox (1965, p.

935). Replicate analyses of 19 saturation extract samples indicate 

reproducibility at the level of ±25 percent of the stated value. Soil 

samples were extracted with NHiAc solutions at pH 7.0, using the 

centrifuging method of Bower, Reitemeier, and Fireman (1952, p. 

253), and analyzed for total extractable Na, K, Ca, and Mg. Results 

are reproducible to within 20 percent of the stated values. Na and K in 

water and NHjAc extracts were analyzed by flame photometry. Ca, 

Mg, and Fe in soil extracts were determined by atomic absorption 

spectrophotometry. Si was analyzed using colorimetric procedures 

described by Kilmer (1965, p. 959-962). P in water-saturation extracts was determined by the methods of Olsen and Dean (1965, p. 

104-107).

Plant samples from the field and greenhouse were washed with 

distilled water and ovendried at 104°C. Into 30-milliliter digestion 

flasks, 0.2000-0.5000 grams of each dry sample was weighed. Five 

milliliters of concentrated HNO3 and HCLO4 were added, and the 

samples were digested overnight in a sand bath. The samples were 

then heated on Kjeldahl burners until they appeared colorless and 

HCLO4 fumes were evident. The solutions were cooled and diluted to 

100 milliliters in volumetric flasks with 10 milliequivalents per liter 

SrCl2 (to mask interferences). Aliquots were taken for subsequent 

analysis. K, Na, Ca, Mg, Fe, and Mn were analyzed by atomic absorption spectrophotometry. P was determined colorimetrically by the 

molybdenum blue method described by Johnson and Ulrich (1959), 

using stannous chloride as a reducing agent. Al was determined by 

the Eriochrome Cyanine R. A. method of Jones and Thurman (1957). 

The methods of Wooley and Johnson (1957, p. 872) were employed in 

the dry ashing and Si analysis of plants. Absolute limits of precision 

are ±20 percent of the given value, but analytical results are within 

±10 percent in all but a few cases.

The preceding discussion has been confined to methods and precision of measurements for any given sample. Statistical computer data 

(table 29) permit a comparison of various physical and chemical soil 

parameters with regard to variation within a given soil type. Geographic patterns of variation within and between soil types were not 

assessed. The figures of table 29, based on samplings of from 12 to 25 

sites per soil type, indicate seven general groups of soil parameter 

variation for this area, decreasing in reliability as follows:

TABLE 28. Comparison of analytical results for some adamellite of Sage Hen Flat (samples 92,98) and Reed Dolomite samples, as analyzed by 

X-ray fluorescence (XRF), wet chemistry (Ken-ichior Aoki), and flame photometry (Joaquim Hampel)

52 bedrock

XRF Aoki Hampel

SiOj __ __ 0.17 0.16 __ _

A12 O3 _ _____ .13 .16 ______

Total Fe 

as FeaOg _ .23 .23 ______ 

MnO _ _ .05 .04

MgO _________ 20.47 21.29 ______

CaO _________ 30.79 31.24 ______

NaaO _ _ __ .04 .03 0.04

K2 O _ _ __ .00 .02 .02

68 bedrock

XRF Hampel

SiC_ __________________ 0.09 ______

Ti02 __________________ .01 ______

A12 O3 __________________ .12 ______

Total Fe

MnO -.- _ ____ _____ .12 _____

MgO __________________ 19.83 ______

CaO ____ _ __ ____ 30.41 __ _

Na2 O __________________ <.01 .03

K2 O ___ __ ___- ___ .00 .01

52 soil, < 2 mm

XRF

41.19

11.48

3.78 

.21 

6.96 

9.16 

1.00 

1.81

68 soil,

XRF

1.49 

.04 

.61

.51 

.12 

19.83 

30.41

'.08

Aoki

23.01 

.44 

7.87

3.56 

.17 

8.86 

22.09 

.46 

.82

>2 mm

Hampel

______

______

".08" 

.07

Hampel

 

______

______

0.48 

.98

54 bedrock

XRF

0.55 

.03 

.40

.39 

.07 

20.75 

29.74

.01

64 bedrock

XRF

0.75 

"19"

.33 

.03 

7.20 

39.69

!05

Aoki

0.59 

0.03

.12

.46 

.03 

7.42 

46.87 

.07 

.06

Aoki

0.81 

.03 

.47

.39 

.05 

21.76 

30.29 

.08 

.07

Hampel

______

_ __ _

0.04 

.03

92 bedrock

XRF

65.83

3.96 

.10 

1.05 

2.37 

3.44 

3.88

Aoki

67.20 

.53 

16.33

3.12 

.06 

.77 

2.86 

3.73 

.11

54 si

XRF

1 35.74 

.47

!8!44 

'14.14 

.72

92 soil,

XRF

65.93

4.73 

.11 

'1.15 

2.14 

3.31 

3.77

ail, < 2 mm

Aoki

35.74 

.50 

9.89

3.14 

.16 

8.44 

14.14 

.16 

1.63

< 2 mm

Aoki

65.40 

.63 

15.77

3.54 

.05 

1.15 

2.32 

3.35 

3.82

Hampel

______

1.55 

1.88

9f

XRF

66.93 

.50

2.67 

.04 

.79 

1.60 

2.84 

3.69

54 soil, > 2 mm

XRF

1.95 

.01 

.08

.53 

.09 

18.54 

30.92 

<.01 

.07

3 soil, < 2

Aoki

69.65 

.43

14.57

2.50 

.04 

.65 

1.63 

3.24 

3.53

Hampel

______

0.07 

.06

mm

Hampel

______

______

~3~.39~ 

3.63

'Valve of Aoki used for standard.
424

EROSION AND SEDIMENTATION IN A SEMIARID ENVIRONMENT 

TABLE 29. Variation in measured parameters of four White Mountains soil types

Reed Dolomite Basalt

Adamellite of 

Sage Hen Flat

Andrews Mountain 

Sandstone

Percent 

standard

Number of deviation 

samples from mean

Percent 

standard

Number of deviation 

samples from mean

Percent 

standard

Number of deviation 

samples from mean

Percent 

standard

Number of deviation 

samples from mean

Range of

percent

standard

deviation

Total extractable K ___________

Total extractable Na ____________

Total extractable Ca __________. 

Total extractable Mg______________

K in water-saturation extracts _______

Na in water-saturation extracts_______

Ca in water-saturation extracts _______

Mg in water-saturation extracts____. 

Percent exchangeable K _________

Percent exchangeable Na___________

Percent exchangeable Ca_____________

Percent exchangeable Mg_________

Sum of exchangeable cations ____ __ 

P in 10:1 water extracts ________ 

High field pH _______________________

Low field pH_______________. 

Mean field pH _____________ 

Laboratory pH______________. 

Soil moisture at %-atm tension _____ 

Soil moisture at 15-atm tension _______

Available water ______________

Soil depth on topographic highs_______

Bulk density________________

Percent fragments greater than 2 mm _

25

25

25

25

21

21

21

21

21

21

21

21

21

18

25

25

25

25

17

23

17

24

24

14

51

31

41

40

78

35

39

36

56

37

9

40

32

73

1

5

1

3

28

45

28

27

34

20

18

18

18

18

17

17

17

17

17

17

17

17

17

17

18

18

18

18

16

17

16

17

17

20

20

16

23

42

53

49

42

19

19

2

12

15

67

8

5

7

4

9

24

21

22

20

22

22

22

22

21

21

21

21

21

21

21

21

21

21

22

22

22

22

22

22

22

21

21

14

37

62

32

31

83

28

40

36

47

33

5

27

29

59

5

16

25

12

22

17

61

26

23

22

18

55

59

51

37

31

17

3

13

14

111

7

14

30

18

14

Te

20-51 

20-62 

16-14 

18-40 

42-83

28-59 

39-51 

36-42 

19-56 

17-37

2- 9

12-40

14-32

59-111

1- 8

5- 8 

1- 8 

3- 7 

9-28 

24-45

12-28 

14-27 

17-34 

16-61

1. Laboratory and field pH

2. Available water, Va-atmosphere moisture, soil depth on topographic highs

3. Exchangeable cations, bulk density

4. Total extractable cations, 15-atmosphere moisture

5. Percentage of soil gravel fragments

6. Cations in water-saturation extracts

7. 10:1 available phosphorus

Many soil surveys and soil descriptions include only one or two 

analyses of these soil properties for each soil series. Information

presented here would suggest that although a few pH and 

%-atmosphere moisture determinations may suffice to characterize 

properties of a soil series as a whole, most other parameters range 

widely within a given soil type and cannot be accurately evaluated by 

a few analyses. The White Mountains soils are, of course, lithosols and 

therefore may show more variation than finer textured soils formed on 

alluvium or strongly developed soils on almost any parent material. 

Nonetheless it is unlikely that analyses at one type locality are 

sufficient to describe accurately properties of a soil series having any 

appreciable lateral extent.

' U.S. GOVERNMENT PRINTING OFFICE: 1974 543 SS3/ 93