Preliminary Geochemical 

Studies in the Capitol 

Reef Area, Wayne County 

Utah

GEOLOGICAL SURVEY BULLETIN 1015-H

This report concerns work done on 

behalf of the U. S. Atomic Energy 

Commission and is published by 

permission of the Commission

Preliminary Geochemical 

Studies in the Capitol 

Reef Area, Wayne County 

Utah

By LYMAN C. HUFF

A CONTRIBUTION TO ECqNOMIC GEOLOGY

GEOLOGICAL SURVEY B

This report concerns work done on 

behalf of the U. S. Atomic Energy 

Commission and is published by 

permission of the Commission

ULLETIN 101S-H

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas 'McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. GovernmentlPrinting Office^ 

Washington 25, D. C. - Price 15 cents (paper cover)
CONTENTS

Abstract_______________________________________ 247

Introduction______________________________________________________ 247

Sample collection..--._________________________|__________--____-_-_ 249

Methods of analysis____________________________________________ 250

Analytical results____________________________|____________________ 250'

Geochemistry of Shinarump uranium deposits.________________________ 252

Bleaching at base of Chinle formation__________________-___-___-----_ 253

Conclusions___________________________________]____________________ 256

Literature cited._____________________________j____________________ 256

ILLUSTRATIONS

Page 

FIGUBE 35. Map of Capitol Reef area, Wayne Coijnty, Utah___________ 247

36. Stratigraphic sections of the Shinarubip and Chinle formations, showing portions sampled for geochemical study. _ _ _ 248

37. Block diagram showing location of geochemical samples collected near Oyler mine________________________________ 249

TABLES

Page

TABLE 1. Analyses of samples of the Chinle formation collected along 

Section E at the Oyler mine, Capitofi Reef National Monument, Utah__________________________ 251

2. Analyses of supplementary series of samples of the Chinle formation, collected near Section E and the Oyler mine, Capitol 

Reef National Monument, Utah__ I ____________________ 253

3. Analyses of samples of the Chinle formation, collected along

Section D near Fruita, about 2 miles from the Oyler mine. _ _ 254

4. Analyses of samples of the Chinle formation, collected along

Section A, near Teasdale, about 14 miles from the Oyler mine. 254

m

A CONTRIBUTION TO ECONOMIC GEOLOGY

PRELIMINARY GEOCHEMIGAL STUDIES IN THE CAPITOL 

REEF AREA, WAYNE COlfNTY, UTAH

By LYMAN C.

ABSTRACT

A bleached zone at the base of the Chinle formation near the Oyler mine, Wayne 

County, Utah, was studied to establish whether there was a chemical relationship 

between bleaching in the Chinle and uranium mineralization in the Shinarump 

conglomerate. The preliminary results suggest that the bleaching was accomplished by a slightly reducing acid solution whictj deposited zinc and copper but 

no uranium in the bleached zone. A field test fdr heavy metals which has been 

devised for geochemical prospecting appears to be satisfactory for detecting and 

tracing such mineralization effects. It is hypothesized that the solution which 

bleached the Chinle also deposited uranium in the Shinarump, but more work is 

needed to clarify this relationship.

INTRODUCTION

Since 1951 the U. S. Geological Survey has had a field party mapping 

and studying the Capitol Reef area (fig. 35) on behalf of the Division 

of Raw Materials, U. S. Atomic Energy Commission. A progress 

report on these geological investigations has been prepared. 1 The

iirsoStratigraphic sections of 

Shinarump and Chinle formations shown on figure 36

7'30"

FIGURE 35. Map of Capitol Reef Area, Wayne County, Utah.

1 Smith, J. F., Jr., Hinrichs, E. N., Huff, L. C., and Luedke, IR. G., 1952, Preliminary report on geologic 

studies in the Capitol Reef area, Wayne County, Utah: U. S. Geol. Survey Trace Elements Mem. Rept. 538.

321861 55 247
;248 CONTRIBUTIONS TO ECONOMIC GEOLOGY

(Oyler Mine)

(Capitol Wash)

- 500 Fe

'Or"iofion ^Shinarump conglomerate

EXPLANATION

Bedded siltstone 

and claystone

Horizontally bedded sandstone 

and sandstone-pebble 

conglomerate

Crossbedded sandstone 

and sandstone-pebble 

conglomerate

Limestone

Locations of sections shown in figure 35

FIGURE 36. Stratigraphic sections of the Shinarump and Chinle formations, showing portions sampled

for geochemical study.

brief geochemical study herewith described is a part of the geologic 

investigation.

The Oyler mine 2 is a uranium deposit in the Shinarump conglomerate and is similar in many respects to other Shinarump uranium 

deposits of the Colorado Plateau. This report describes a chemical 

study made of the Chinle formation and its possible significance. 

The chemical study was made to investigate a light-colored bleached 

zone which is commonly found at the base of the Chinle formation 

and which is well developed near the Oyler mine. In particular, the

* Smith and others, op. cit.
PRELIMINARY GEOCHEMICAL STUDIES, CAPITOL REEF AREA, UTAH 249

chemical study was designed to establish whether the bleached zone 

in the lower Chinle is related genetically to the uranium mineralization of the Shinarump.

SAMPLE COLLECTION

Two suites of samples of the Chinle formation were collected near 

the Oyler mine and for background data two other suites were collected, at a considerable distance from the mine. The suites collected 

near the Oyler mine were taken in a traverse across the bottom half 

of the Chinle formation; the other two suites were taken in a traverse 

across the entire formation. In all, 188 samples of the Chinle were 

collected. Figure 36 shows the stratigraphic relationships of these 

samples. Figure 37 shows in greater detail the location of samples 

collected near the Oyler mine.

200' 200' 

EXPLANATION

300' 400'

«- N34°E

Point of sample ond number 

FIGURE 37. Block diagram showing location of geochemical samples collected near Oyler mine.

Grab samples of undisturbed Chinle just beneath the land surface 

were collected with a chisel-edged pick and were stored in cardboard 

cartons or manila envelopes. Two closely spaced samples were collected at many of the sample sites so that some samples would be 

available for confirming the results. Most sample sites were marked 

with numbered wooden stakes and the intervening slope distances 

measured with a 100-foot tape. This marking system permitted 

collection of additional samples anywhere along the traverses without 

error of location. In general, samples were collected at intervals 

close enough to sample each lithologic type, or where the rock is 

homogeneous, at 100-foot slope intervals.

A field description of the samples, recorded as they were collected, 

included sample location, grain-size classification, color according to 

the rock-color chart (Goddard and others, 1948), presence of calcium 

carbonate by acid test, and other pertinent features.
250 CONTRIBUTIONS TO ECONOMIC GEOLOGY

METHODS OF ANALYSIS

The Geological Survey analyzed all samples by the total heavymetal test developed by Huff (1951). The total heavy-metal test is 

a group test for detecting the presence in trace amounts of any ore 

metal such as copper, lead, and zinc which react with the reagent 

dithizone. The heavy-metal test is not affected by uranium, vanadium, iron, or manganese. The test revealed no heavy metals for 

the bulk of the Chinle samples. Heavy metals were found only in 

the bleached zone of the lower Chinle, in a very few bleached zones 

higher in the Chinle, and in the thin bleached zone at the top of the 

Chinle, below the Wingate sandstone.

Additional analyses were made of samples collected near the base 

of the Chinle. These samples were analyzed for copper, lead, zinc, 

and acidity (pH). Acidity was measured by the method used by 

agricultural scientists for soils (U. S. Bur. Soils, 1951, p. 237). The 

acidity of a suspension of the ground sample in distilled water was 

measured with an electric pH meter. The pH measured ranged from 

about 4.0 (acid) in the bleached zone to slightly over 8.0 (alkaline) in 

the unbleached Chinle.

The oxidation potential of several samples was investigated with 

the help of R. M. Garrels and Harold Bloom. Details concerning the 

measurement of oxidation potentials are given by ZoBell (1946). 

Oxidation potentials of samples 1 to 6 were measured with a platinum 

instead of a glass electrode in the pH meter. Nitrogen was bubbled 

through the sample during measurement to expel oxygen and stir the 

suspension. The Coleman pH meter used gave stable Eh potentials 

with the Chinle samples after bubbling nitrogen for about 15 minutes.

Because of the few samples involved the meter used for measuring 

oxidation potential was not standardized with an oxidation-reduction 

buffer. The measurements ranged from 354 millivolts in sample 1 

to 125 millivolts for sample 6. Expressed in terms of the standard 

hydrogen cell, the corresponding values would be approximately 

 108 and +121 millivolts. In simplified terms the range is from 

reducing conditions in the bleached Chinle to oxidizing conditions in 

the unbleached Chinle.

Ten samples were analyzed for uranium (table 1) and for equivalent 

uranium. In addition, the writer made qualitative microchemical 

tests of representative samples for copper, lead, zinc, iron, manganese, 

vanadium, uranium, carbonate, sulfate, and phosphate.

ANALYTICAL RESULTS

Analyses of samples collected near the Oyler mine are given in 

tables 1 and 2. The bleached zone of the lower Chinle near this mine 

contains several hundred parts per million zinc and about one hundred
PRELIMINARY GEOCHEMICAL STUDIES, CAPITOL REEF AREA, UTAH 251

TABLE 1. Analyses of samples of the Chinle formation, collected along section E at 

the Oyler mine, Capitol Reef National Monument, Utah

[Two determinations are listed for analyses of duplicate samples. H. E. Crowe, W. M. Mountjoy, and

J. P. Schuch, analysts]

Field 

no.

10

9

8

7

6

5

4

3

2

1

Sample description

Claystone, sandy and silty, lightolive-gray, 51.0 ft above base of

Chinle.

Siltstone, sandy, grayish-red, 43.2

ft above base of Chinle.

Siltstone, sandy, grayish-red, 30.9

ft above base of Chinle.

Sandstone, fine, pale-reddishbrown, 22.3 ft above base of

Chinle.

Sand and siltstone, fine, reddishbrown, 16.7 ft above base of

Chinle.

Sand and siltstone, fine, reddishbrown, 11.4 ft above base of

Chinle.

Sandstone, fine, clayey, reddishbrown, 5.9 ft above base of

Chinle.

Sandstone, clayey, yellowish iron

stain, 4.7 ft above base of Chinle.

Claystone, sandy, light-olive-gray,

3.8 ft above base of chinle.

Claystone, light-olive-gray, 1.1 ft

above base of Chinle and top of

Shinarump.

Total 

heavy 

metal 

(ppm)

20,0

0,0

0,0

20,0

0,0

0,0

90,30

150, 170

330, 300

450, 450

Zinc 

(ppm)

10

10

10

10

10

10

20

170

300

600

Lead 

(ppm)

20

10

10

10

10

10

10

10

10

10

Copper 

(ppm)

20

20

10

10

10

10

20

50

SO

100

Uranium 

(ppm)

4

. 3

1

2

2

2

2

3

5

25

PH

8.0

8.5

8.1

7.6

8.1, 8.2

8.3, 8.3

6.1, 6.1

4.7, 4.8

4.2, 4.2

4.2, 4.0

parts per million copper. The unbleached beds higher in the Chinle 

contain a low heavy-metal content.

Analyses of samples collected far from the Oyler mine are given 

in tables 3 and 4. These samples show little or no concentration of 

zinc or copper at the base of the Chinle formation.

The detection, identification, and tracing of heavy-metal anomalies 

amounting to only several hundred parts per million has been proven 

feasible by many geochemical prospecting studies. The duplicate 

results given under "total heavy metal" and "pH" columns (tables 

1 and 3) were obtained from separate samples and give a measure of 

the reproducibility of the results. In other words, the variations 

shown are due to both local variation of metal content and to analytical 

errors. Such a comparison permits evaluation of the ability to 

reproduce measurements in terms of the amount of natural variations. 

Although of small magnitude, the presence of a heavy-metal anomaly 

in the basal Chinle seems fairly well established.

Sample 1, at the base of the bleached zone, contains 25 ppm (parts 

per million) uranium (table 1). The higher samples, 3 to 10, contain 

only 1 to 4 ppm uranium. Experiments indicate that 25 ppm
252 CONTRIBUTIONS TO ECONOMIC GEOLOGY

uranium is not detectable by the field (bead) test for uranium. 

Apparently the uranium, anomaly is less extensive and not as readily 

detectable by field tests as the heavy-metal anomaly.

Qualitative microchemical tests on samples listed in table 1 confirmed the presence of abnormal amounts of zinc and copper in the 

bleached zone. In addition, the microchemical tests indicate that 

the bleached beds contain more sulfate but less iron and carbonate 

than the unbleached beds. Microchemical tests revealed no abnormal 

amounts of lead, vanadium, manganese or phosphate in either bleached 

or unbleached beds. Apparently, the bleaching removed iron and 

carbonate and added sulfate, zinc, copper, and uranium.

GEOCHEMISTRY OF SHINARUMP URANIUM DEPOSITS

Before the relation between the bleached Chinle and the uranium 

deposits can be considered, it might be advantageous to review briefly 

the behavior of the ore metals of Shinarump-type uranium deposits 

under different conditions of acidity and oxidation. Krumbein and 

Garrels (1952) have shown that metals such as iron, uranium, copper, 

and zinc are appreciably soluble in slightly reducing acid solutions 

and can be precipitated either by additional reduction or by neutralizing the acid. If precipitation is caused by additional reduction, the 

minerals formed contain ions in their reduced form such as U4+, V3"1", 

Cu1+, Fe2+, and S2~. Pitchblende, pyrite, and chalcopyrite are examples of minerals in this assemblage which have been identified at 

the Oyler mine. If precipitation is caused by neutralization, the 

minerals formed contain ions in their oxidized form such as U6+, V5+, 

Cu2+ Fe3+ and S6+. Zippeite (UO2 ) (SO4 ) (OH)2 4H2O, metatorbernite 

Cu(UO2 ) 2 (PO4 ) 2 -8H2O,johanniteCu(UO2 ) 2 (SO4 ) 2 (OH) 2 -6H2O, gypsum, 

alunite, and malachite are examples of minerals in this assemblage 

at the Oyler mine. Although there may be many complicating factors, such as the effects of temperature and pressure, the writer believes that it would be helpful in understanding the chemistry of the 

uranium deposits such as those in the Oyler mine if the minerals 

present are classified in two broad groups: (1) Minerals precipitated 

by reduction and (2) minerals precipitated by neutralization or 

oxidation.

Both chemical and mineralogical evidence are needed to decipher 

the history of the Shinarump-type deposits. With the ore minerals 

classified as they are above the writer interprets the genesis of the 

Shinarump ore as follows: Precipitation of minerals of the reduction 

assemblage in the vicinity of organic materials, and later alteration 

of some of the ore with slight migration of its constituents to minerals 

of the oxidation assemblage. It is inconceivable, on the basis of 

chemistry and textural relationships, that minerals of both assem-
PRELIMINARY GEOCHEMICAL STUDIES, CAPITOL REEF AREA, UTAH 253

blages could have been deposited together. The alteration from reduced to oxidized minerals can be attributed to the effects of ground 

water, which is normally slightly alkaline and has a slight tendency 

to oxidize. The original precipitation of the ore minerals is conjectural but, unless it took place under abnormal conditions of pressure 

.and temperature, the ore solutions were probably mildly reducing and 

acid in character. As suggested by Krumbein and Garrels (1952), it 

is only solutions of this tvpe wT hich can carry significant quantities of 

the ore metals in solution. Such solutions must have been quite different chemically from most present-day ground water.

BLEACHING AT BASE OF CHINLE FORMATION

No ore minerals have been identified in the basal, bleached zone of 

the Chinle. The composition and nature of the solution which caused 

the bleaching must be inferred from the chemical changes involved in 

the bleaching. The bleaching involved removal of iron and carbonate 

and addition of sulfate, zinc, copper, and uranium (tables 1, 2 and fig. 

37). Only an acid solution, except at abnormal temperatures, would 

be expected to deposit zinc and copper as it is neutralized by carbonate. Moreover, only a slightly reducing acid solution would be

TABLE 2. Analyses of supplementary series of samples of the Chinle formation, 

collected near section E and the Oyler mine, Capitol Reef National Monument, 

Utah

[H. E. Crowe, analyst]

Field 

no.

28

27

26

25

24

23

22

21

20

19

18

Sample description

Silt, clayey, light-olive-gray, 103.0 ft above base

of Chinle.

Silt, clayey, light-olive-gray, 73.0 ft above base of

Chinle.

Claystone, light-olive-gray, 59.0 ft above base of

Chinle.

Claystone, silty, light-olive-gray, 46.4 ft above

base of Chinle.

Siltstone, reddish-brown, 35.8 ft above base of

Chinle.

Siltstone, reddish-brown, 21.8 ft above base of

Chinle.

S'lt, sandy, reddish-brown, 14.2 ft above base of

Chinle.

Siltstone, clayey, reddish-brown, 8.8 ft above

base of Chinle.

Siltstone, yellowish-orange, 6.0 ft above base of

Chinle.

Claystone, light-olive-gray, 3.6 ft above base of

Chinle.

Claystone, light-olive-gray, 0.5 ft above base of

Chinle and top of Shinarump.

Total 

heavy 

metal 

(ppm)

0

0

0

0

0

0

0

0

250

300

350

Zinc 

(ppm)

20

20

20

20

20

20

20

20

300

700

350

Lead 

(ppm)

20

10

20

10

10

10

10

10

10

20

50

Copper 

(ppm)

10

10

10

10

20

10

20

20

£C

15C

10C

pH

8.4

8.1

6.6

6.7

7.9

8.2

7.9

7.6

4.8

3.5

3.7
254 CONTRIBUTIONS TO ECONOMIC GEOLOGY

expected to dissolve iron. Thus, the known geochemical behavior of 

these elements indicates a slightly reducing acid solution was responsible for the bleaching.

At the locality where the Shinarump conglomerate is lacking, the 

basal Chinle formation has no heavy-metal anomaly or bleached zone 

(table 3). At another locality where unmineralized Shinarump conglomerate lies beneath the Chinle formation, the basal Chinle isbleached but shows only a small metal anomaly (table 4). At countTABLE 3. Analyses of samples of the Chinle formation, collected along section D 

near Fruita, about 2 miles from the Oyler mine

[Two determinations are listed for analyses of duplicate samples. H. E. Crowe, analyst]

Field 

no.

160

159

158

157

156

155

154

153

152

151

Sample description Total heavy 

metal (ppm)

o,r>

0,0

0,0

0,0

0,0

0, 0>

0,0

0,0

0,0

0,0>

TABLE 4. Analyses of samples of the Chinle formation, collected along section A, 

near Teasdale, about 14 miles from the Oyler mine

[H. E. Crowe, analyst]

Field 

no.

210

209

208

207

206

205

204

203

202

201

Sample description

Claystone, silty, light-olive-gray, 63.2 ft above

base cf Cbinle.

Claystone, light-olive-gray, 42.0 ft above base

of Chinle.

Claystone, silty, light-olive-gray, 38.2 ft above

base of Chinle.

Claystone, silty, light-olive-gray, 32.7 ft above

base of Chinle.

Claystone, dark-reddish-brown, 24.7 ft above

base of Chinle.

Claystone, dark-reddish-brown, 11.0 ft above

base of Chinle.

Claystone, dark-reddish-brown, 9.7 ft above

base of Chinle.

Claystone, silty, light-olive-gray, 7.2 ft above

base rf Chinle.

Claystone, silty, light-olive-gray, 6.0 ft above

base of Chinle.

Claystone, silty, light-clive-gray, 2.5 ft above

base of Chinle and top of Shinarump.

Total 

heavy 

metal 

(ppm)

0

70

0

0

0

0

0

30

120

100

Zinc 

(ppm)

10

70

10

20

10

10

10

SO

70

50

Lead 

(ppm)

10

10

10

10

Ml

10

10

10

20

10

Copper 

(ppm)

10

20

10

10

20

10

10

20

10

20

PH

7. a

8.1>

8.1

8.1

7.6

4.7

4.7

4.5

5.4

7.4
PRELIMINARY GEOCHEMICAL STUDIES, CAPITOL REEF AREA, UTAH 255

less other localities examined but not sampled the basal Chinle and 

uppermost Moenkopi are bleached if Shinarump conglomerate is present. 

If the Shinarump conglomerate is absent so is the bleaching. The 

bleaching, therefore, seems to have been accomplished by solutions in 

the permeable Shinarump conglomerate.

The relationship between the ore deposition and the bleaching is 

significant because the correct interpretation of this relationship may 

lead to better understanding of the ore genesis. Three possibilities 

present themselves: Bleaching preceded ore deposition, bleaching 

accompanied ore deposition, and bleaching followed ore deposition.

If the bleaching preceded ore deposition the Shinarump conglomerate must have been saturated with a slightly reducing acid solution 

prior to ore deposition. The bleaching solution must have contained 

copper and zinc because these metals were deposited hi the bleached 

zone. Such a solution would have to have been similar to the orebearing solution except for the absence of uranium. Explaining the 

successive appearance of two slightly reducing acid solutions differing 

only with respect to their uranium content presents many difficulties.

If the bleaching accompanied ore deposition they were probably 

both effects of the same solution. Both effects were caused by a 

slightly reducing acid solution. The simplicity of this explanation 

lends it support.

If the bleaching followed ore deposition the bleaching was probably 

caused by normal ground water hi the zone of oxidation. Normal 

ground water which has come in contact with oxidizing sulfides could 

readily acquire the slightly reducing acid character requisite for iron 

solution. Some bleaching near uranium deposits is undoubtedly of 

this type (Alice Weeks, oral communication, 1954).

The samples collected near the Oyler mine were all collected close 

to the land surface and undoubtedly have been subjected to the affect 

of weathering. However, the bleached zone appears to be related more 

to the upper contact of the Shinarump conglomerate than it is to the 

land surface. In other areas, both in Shinarump and Morrison ore 

deposits, similar bleaching has been noted associated with deep 

unoxidized ore. In addition, the amount of bleaching is known to 

increase near ore and has even been used as a guide in prospecting. 

It is for these reasons, in addition to the chemical evidence mentioned, 

that the writer believes that most of the bleaching was probably caused 

by the ore solutions.

In whatever manner the history of the bleached zone is interpreted, 

the results of this brief chemical study indicate that primary dispersion of heavy metals in the vicinity of the uranium deposits may be 

more extensive than the primary dispersion of the uranium itself. If 

this relation can be verified by additional study, field tests for heavy
256 CONTRIBUTIONS TO ECONOMIC GEOLOGY

metals might prove to be useful as a prospecting guide. Some ore 

deposits are characterized by dispersion of an associated element 

exceeding that of the ore metal of primary economic interest. Warren, 

DeLavault, and Irish (1952) have investigated the possibilities of 

using analyses of the associated elements for prospecting and use the 

name "pathfinder" for the element of great dispersion which is 

detected by analysis. By this terminology zinc and copper would be 

pathfinder elements if they can be used to guide the way to the 

Shinarump uranium deposits.

Besides indicating the chemical conditions of uranium deposition 

and possible geochemical prospecting applications, geochemical studies 

also offer some possibility of tracing the solution passageways. The 

thinness of the bleached zone at the Oyler mine argues against much 

local downward percolation of reducing acid solutions through the 

main mass of the Chinle. Extension of the CbinJe studies and similar 

studies of the Moenkopi and the Shinarump formations might yield a 

three-dimensional picture of solution passageways helpful in determining the source of the uranium.

CONCLUSIONS

Near the Oyler mine a bleached zone at the base of the Chinle 

formation contains abnormal amounts of zinc and copper. This 

bleached zone also differs chemically from the bulk of the Chinle 

formation in respect to acidity, oxidation potential, and iron content. 

It is hypothesized that the bleaching and associated chemical changes 

that took place in the lowermost Chinle were caused by the same solutions which deposited the ore in the Shinarump conglomerate. Whether 

this hypothesis proves to be correct or not it seems evident that 

chemical studies may help clarify the genesis of the ore and offer promise 

of application of geochemical prospecting.

LITERATURE CITED

Goddard, E. N., and others, 1948, Rock-color chart: Washington, D. C., National 

Research Council. 6 p.

Huff, L. C., 1951, A sensitive field test for detecting heavy metals in soil or sediment: Econ. Geology, v. 46, no. 5, p. 524-540.

Krumbein, W. C., and Garrels, R. M., 1952, Origin and classification of chemical 

sediments in terms of pH and oxidation-reduction potentials: Jour. Geology, 

v. 60, no. 1, pi 1-33.

Warren, H. V., DeLavault, R. E., and Irish, R. I., 1952, Preliminary studies on 

the biogeochemistry of iron and manganese: Econ. Geology, v. 47, no. 2, p.. 

131-145.

ZoBell, C. E., 1946, Studies on redox potential of marine sediments: Am. Assoc. 

Petroleum Geologists Bull., v. 30, p. 477-513.

U. S. Bureau of Soils, 1951, Soil Survey manual: U. S. Dept. Agriculture Handbook 18.

U. S. GOVERNMENT PRINTING OFFICE: 1955