Stratigraphy and Composition of 

the Sharon Springs Member of 

the Pierre Shale in Western Kansas

GEOLOGICAL SURVEY PROFESSIONAL PAPER 728

Stratigraphy and Composition of 

the Sharon Springs Member of 

the Pierre Shale in Western Kansas

By JAMES R. GILL, WILLIAM A. COBBAN, and LEONARD G. SCHULTZ

GEOLOGICAL SURVEY PROFESSIONAL PAPER 72

Stratigraphic and miner alogic study of 

one of the more distinctive and widespread 

shale units of Late Cretaceous age in the 

western interior of the United States

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1972
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 72-600083

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

Washington, D.C. 20402 - Price 75 cents (paper cover)

Stock Number 2401-2104
CONTENTS

Abstract.............................................

Introduction......................................

Acknowledgments.............................

Historical background.....................

Geologic setting................................

Stratigraphic resume......................

Niobrara Formation................

Pierre Shale ...... ...................

Sharon Springs Member. 

Weskan Member...............

Lake Creek Member.........

Salt Grass Member..........

Unnamed member............

Beecher Island Member... 

Sharon Springs Member.................

Dark soft shale unit.................

Organic-rich shale unit...........

Phosphatic shale unit. ... 

Rate of sedimentation..............

1

1

3

3

5

6

6

7

7

7

9

10

10

10

10

11

11

14

16

Composition.......... ................................................................

Previous studies..... ............ .......... . ...............

Mineralogy ..............................................................

Niobrara Formation...........................................

Sharon Springs Member of the Pierre Shale. 

Upper members of the Pierre Shale. 

Bentonites.............................................................

Basaluminite and hydrobasaluminite. ..........

Potassium feldspar....................... ...................

Barite and apatite..............................................

Chemical composition.................................................

Mode of occurrence of elements.----------. ------

Leaching of surface samples...... ... ...........

Bentonites.............................................................

Comparison with other shales...... ..

Major elements . 

Minor and trace elements..........................

Measured sections...-.-.--------.- ............ ........ . .

References cited.................... ....... .............. . 

Index.......... ........................................ ... 

Page

20

20

22

23

23

24

24

26

30

30

31

34

37

37

37

37

38

39

45

49

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Mollusks from the Baculites obtusus zone.

2. Mollusks from the Baculites asperiformis zone.

Page

FIGURE 1. Map showing location of six measured sections 2

2. Paleogeographic map during latter part of Niobrara time 6

3. Chart showing time span of Pierre Shale in western Kansas and equivalent rocks in nearby States......... 8

4. Graphic section and electric log of Sharon Springs Member of Pierre Shale in Wallace and

Logan Counties, Kans............................................................................................................................................... 12

5-8. Photographs showing:

5. Contact of Sharon Springs Member and Niobrara Formation...--......--- .. 14

6. Outcrop of dark soft shale unit of Sharon Springs Member--.-....... 15

7. Hard buttress-weathering shale of Sharon Springs Member. . . 16

8. Northeasternmost outcrop of Sharon Springs Member..-............-.....-................. . 17

9. Diagram showing eastward and upward migration of organic-rich shale unit of Sharon Springs Member.. 17

10. Paleogeographic map of early stage of deposition of Sharon Springs Member 18

11-15. Photographs showing:

11. Gypsum rosettes............... ................................................................................................................................ 18

12. Irregularly shaped limestone concretions....--.-......--.--.----.--..... 18

13. Septarian limestone concretions........-.......-.-.............................--..--...---...-.-...................... 18

14. Cone-in-cone limestone concretions............................................................................. .........--- ..... 19

15. Contact of phosphatic and organic-rich shale units. ........................ .. . 19

16. Paleogeographic map of late stage of deposition of Sharon Springs Member.....-..... 19

17. Electric and gamma-ray log correlation in Kansas, Colorado, Nebraska, and South Dakota. 20

ill
IV CONTENTS

FIGURES 18-22. Photographs showing:

18. Phosphatic shale unit...............................................................................................................

19. Contact of Sharon Springs and Weskan Members. ........................................................

20. Phosphate nodule from phosphatic shale unit....................................................................

21. Phosphate nodules from phosphatic shale unit..................................................................

22. Contact of Sharon Springs and Weskan Members.............................................................

23. Diagram showing thickness and implied rates of sedimentation of Pierre Shale in western 

Kansas and other localities....................... ...................................................................................

24. Schematic structure of a montmorillonite layer....................... .......................................................

25. Graph showing distribution of elements in sample cuttings from the Guy Holland test hole.

Page

22

22

22

23

24

28

30

32

TABLES

TABLE 1. Analyses of sample cuttings from the Sharon Springs Member of the Pierre Shale and the

Smoky Hill Member of the Niobrara Formation from the Guy Holland test hole.....................

2. Analyses of samples from the Sharon Springs and Weskan Members of the Pierre Shale from

outcrops near the Guy Holland test hole..... ......................................................................................

3. Mineralogy of samples from the Pierre Shale... ......................................................................................

4. Mineralogy of bentonites............................................... ................................................................................

5. Approximate lower limits for visual detection of elements......................................................................

6. Mean content and inferred occurrence of chemical elements and minerals in samples from the

Pierre Shale and Niobrara Formation....................--....-----....-.-... --....................................................

7. Correlation coefficients between elements and minerals in sample cuttings from the Guy Holland 

test hole and nearby outcrops-..-.......--......-... ........................................................................................

Page

26

28

30

30

31

33

34
STRATIGRAPHY AND COMPOSITION OF THE SHARON SPRINGS MEMBER 

OF THE PIERRE SHALE IN WESTERN KANSAS

By JAMES R. GILL, WILLIAM A. COBBAN, and LEONARD G. SCHULTZ

ABSTRACT

The Sharon Springs Member of the Pierre Shale is a widespread unit that can be recognized readily in outcrops by its 

distinctive lithologic character and in the subsurface by electric and gamma-ray well-log characteristics. The Sharon 

Springs Member is in Kansas, Nebraska, North and South 

Dakota, and parts of Colorado, Wyoming, Montana, and eastern Utah. Its type locality is in Wallace County, Kans., where 

the member is about 215 feet thick and consists of three units: 

a lower dark soft shale unit 115 feet thick, a middle hard organic-rich shale unit 90 feet thick, and an upper hard slightly 

phosphatic shale unit about 10 feet thick. The Sharon Springs 

contains abundant vertebrate remains but few mollusks.

Minerals in the Sharon Springs Member, as determined 

from well cuttings, are predominantly clay minerals but include about 25 percent quartz and several percent each of 

pyrite, dolomite, organic matter, and, in the lower part where 

the member grades into the Niobrara Formation, calcite. The 

most abundant clay mineral is mixed-layered montmorilloniteillite; there are lesser amounts of illite, kaolinite, and chlorite. 

Pyrite, dolomite, and chlorite are leached from outcrops. Bentonite beds in the Sharon Springs contain unusually large 

amounts of kaolinite and beidellite with interlayered hydrated 

aluminum complexes in comparison with the usual montmorillonitic bentonites in other parts of the Pierre Shale. The rare 

mineral basaluminite occurs as white earthy lumps at the top 

of the Sharon Springs Member.

Semiquantitative spectrographic data indicate that most 

trace elements occur in the clay component of the shale or in 

closely associated heavy clastic grains. Iron, nickel, cobalt, and 

molybdenum are concentrated in pyrite. Molybdenum and 

probably uranium and silver seem strongly concentrated in 

organic matter. Strontium is concentrated in calcite.

INTRODUCTION

The Pierre Shale, which includes the Sharon 

Springs Member at its base, is chiefly a marine 

medium- to dark-gray noncalcareous shale of Late 

Cretaceous age that overlies the calcareous Niobrara 

Formation and underlies the Fox Hills Sandstone.

The maximum thickness in Kansas is about 1,600 

feet in extreme northwestern Cheyenne County 

(Merriam, 1963, p. 42). Elias (1931, p. 56-57) 

divided the Pierre into the following members, from 

oldest to youngest: Sharon Springs, Weskan, Lake 

Creek, Salt Grass, an unnamed member, and Beecher 

Island.

The Sharon Springs Member of the Pierre Shale 

is stratigraphically unique. It differs from the rest 

of the Pierre Shale because of its dark color, resistance to erosion, richness in organic material, and 

high radioactivity. At most localities, many bentonite beds are in the lower part of the member, and 

gray septarian limestone concretions are conspicuous in many places. The member derives its name 

from the town of Sharon Springs in Wallace County 

near the west boundary of Kansas (fig. 1).

From 1956 to 1968, a detailed regional study of 

the stratigraphy, paleontology, mineralogy, and 

geochemistry of the Pierre Shale and equivalent 

rocks in the northern part of the western interior 

was undertaken by various members of the U.S. 

Geological Survey (Tourtelot, 1956, 1962; Tourtelot 

and others, 1960; Schultz, 1964, 1965; Scott and 

Cobban, 1963, 1965; Barnett, 1961; Rader and 

Grimaldi, 1961; Kepferle, 1959; Landis, 1959; Gill 

and Cobban, 1961, 1962, 1965, 1966a, b; Robinson 

and others, 1959). During this investigation, they 

studied type sections of members of the Pierre Shale 

along the Missouri River and in the Black Hills 

region in South Dakota as well as the equivalent 

rocks in North Dakota, Montana, Wyoming, and 

Colorado. That the Pierre Shale is a diverse lithologic sequence marked by east-west facies changes 

which are subtle in some places and conspicuous in 

others soon became apparent and made correlation

l
THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

of individual units difficult. However, the Sharon 

Springs Member was found to be so nearly uniform 

in lithology over long distances that it could be easily 

identified on the surface and in the subsurface 

throughout much of the western interior of the 

United States and the adjacent region in southern 

Canada.

Geological Survey of Kansas drilled two test holes 

in the fall of 1962, one near McAllaster and the 

other near Sharon Springs. The test hole near 

McAllaster penetrafed 50 feet of the Sharon Springs 

Member and 115 feet of the underlying Smoky Hill 

Member of the Niobrara Formation. The test hole 

near Sharon Springs penetrated the entire Sharon

,r111

s.l

^i

R. 42 W. 

102°__

 

KANSAS

W A L L A C E

41 40 39 38 37 36 35 " \ ~~ v\

34 101° 33 R 32 W

McAllaster

LOG A N

i

01

13g

i-q 

0| u lSharon ^T&oky oRussell Springs

sl:an

O

&,.

 fiutte

ElkaderO

1

10 20 MILES

FIGURE 1. Location of six measured sections of the Sharon Springs Member of the Pierre Shale. (Town of Lisbon is

abandoned.)

Throughout most of the western interior, the 

Sharon Springs Member is characterized by shale 

that is rich in organic material as well as by persistent bentonite beds in the lower unit. Distinctive 

electric and gamma-ray log characteristics permit 

delineation of the western edge of shale that is 

rich in organic material and subsurface tracing 

of the bentonite beds westward from this area into 

areas of nearshore deposition.

A brief reconnaissance of exposures of the Sharon 

Springs Member in Wallace and Logan Counties was 

made in the fall of 1959 and in the spring of 1960 

to determine the thickness, lithology, and fossil 

content of the unit. Only part of the thickness of the 

member could be measured at any one locality; 

therefore, to determine total thickness, the State

Springs Member (222 feet) and 78 feet of the 

Smoky Hill Member.

Outcrops of the Pierre Shale, including those of 

the Sharon Springs Member, are generally poor in 

western Kansas. In Wallace and Logan Counties, 

most exposures of the Sharon Springs Member are 

restricted to the main and tributary valleys of Twin 

Butte Creek and the North and South Forks of the 

Smoky Hill River. (See maps by Hodson, 1963, pi. 1, 

and Johnson, 1958, pi. 1.) Owing to the fact that the 

Sharon Springs Member is unconformably overlain 

by deposits of Tertiary and Quaternary age in much 

of these areas, a complete section of the member cannot be obtained at any single locality. Six partial sections (fig. 1, loc. 1-6), the location of which follows 

immediately, were measured and are included in 

this report.
HISTORICAL BACKGROUND

Loc. Location

1 NE%NE% sec. 20, T. 15 S., R. 32 W., Logan County.

2 SE% sec. 13, T. 12 S., R. 37 W., Logan County.

SWHNE& sec. 13, T. 12 S., R. 37 W., Logan County 

(McAllaster Buttes test hole).

3 SE% sec. 20, T. 12 S., R. 36 W., Logan County.

4 SWi/iSE 1/* sec. 33, T. 12 S., R. 36 W., Logan County.

5 SE%NE% sec. 32, T. 13 S., R. 37 W., Logan County.

6 SW%SE%NW% sec. 36, T. 13 S., R. 40 W., Wallace

County.

SE^SEi/iNWi/i sec. 36, T. 13 S., R. 40 W., Wallace 

County (Guy Holland test hole, Devils Half acre).

In Phillips County, a remnant of the lower unit of 

the Sharon Springs is preserved in a fault block 

exposed along Prairie Dog Creek (Frye and Leonard, 1949, p. 31, pi. 5) ; this exposure was also 

measured.

ACKNOWLEDGMENTS

We acknowledge the assistance of D. F. Merriam, 

formerly with the State Geological Survey of Kansas, in arranging for the drilling of the two holes 

in the study area and for encouragement in preparing the report. Our colleagues in the U.S. Geological Survey, I. C. Frost, J. C. Hamilton, Lorraine 

Lee, H. H. Lipp, Wayne Mountjoy, and G. D. Shipley, provided analyses. Robert E. Burkholder, also 

of the U.S. Geological Survey, photographed the 

fossils and phosphatic nodules.

HISTORICAL BACKGROUND

Many of the early observations of the rocks now 

assigned to the Sharon Springs Member of the 

Pierre Shale were incidental to the descriptions of 

fossils, chiefly vertebrates, from western Kansas. 

Cretaceous strata of the Great Plains were first 

divided into the following formations (Meek and 

Hayden, 1861, p. 419) :

Formation

Fox Hill beds.............................................. 5

Fort Pierre Group...................................... 4

Niobrara Division...................................... 3

Fort Benton Group.................................... 2

Dakota Group.............................................. 1

The Fort Pierre Group [Pierre Shale] was not subdivided.

In 1867, Dr. Theophilus H. Turner, physician at 

Fort Wallace, Kans., collected parts of three large 

vertebrae which he presented to John L. LeConte, 

who was engaged in a geological survey to determine the route for the Union Pacific Railway. 

LeConte passed these on to Prof. E. D. Cope, who 

indicated that they belonged to a large marine reptile (plesiosaur). Shortly thereafter Dr. Turner collected the remaining bones and sent them to Cope,

who briefly described them as the new species 

Elasmosaurus platyurus Cope (1868a, b). Cope 

(1868b) noted that more than 100 vertebrae were 

present and that the original length of the vertebral 

column must have been 38 feet. This huge plesiosaur 

became the subject of many papers, mainly as a 

result of Joseph Leidy's conclusion that Cope had 

misidentified the order of the vertebrae from head 

to tail (Leidy, 1870a, b; Cope, 1870, 1875). Regarding the rock which yielded the specimen, Cope 

(1868b, p. 93) stated, "The beds were argillaceous, 

with much gypsum [selenite]; the latter mineral 

coating the bones." It is now known that Cope's 

specimen came from the Sharon Springs Member, 

the outcrops of which ordinarily have numerous 

crystals and joint fillings of selenite. The outcrops 

are characterized also by many septarian limestone 

concretions that contain thick veins of pale-yellow 

calcite and scattered barite crystals. Cope's paper 

(1868b) is an appendix to a much larger report by 

LeConte, who examined some of the barite and made 

the following statement (LeConte, 1868, p. 11) : "I 

received from Dr. Turner, U.S.A., the medical officer 

of the post [Fort Wallace], several fine crystals of 

sulphate of baryta, found in geodes, with calcite and 

selenite, about seven miles west of the fort. * * * 

Dr. Turner had found in the same ravine with the 

geodes some irrecognizable fragments of fossil 

bone." This statement and that of Cope (1868b) 

may be the first description of rocks now assigned 

to the Sharon Springs Member.

Cope (1871) spent part of the fall of 1871 in the 

Fort Wallace area. He (1872a, p. 325) noted that in 

the Fort Hays-Fort Wallace area the "Niobrara 

division" consisted of two parts "a lower of dark 

bluish calcareo-argillaceous character, often thinbedded ; and a superior, of yellow and whitish chalk, 

much more heavily bedded." He apparently mistook 

the dark shale in the Fort Wallace area, now assigned to the Sharon Springs Member, for the lower 

part of the "Niobrara division." Cope (1872a, p. 

326) described the beds as follows:

The blue shale * * * frequently contains numerous concretions, and great abundance of thin layers of gypsum and 

crystals of the same. Near Sheridan [a former town a few 

miles east of what is now McAllaster1 ], concretions and septaria are abundant. In some places the latter are of great 

size, and being imbedded in the stratum have suffered denudation of their contents, and the septa standing out form a 

huge honey-comb.

1Mohler (1889, map on page 278) showed McAllaster to be along the 

Union Pacific Railroad, just north of the center of sec. 23, T. 12 S., R. 

37 W., and Sheridan to be along this railroad east of the North Fork of 

Smoky Hill River in about the W% sec. 8, T. 12 S., R. 36 W.
THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Cope described the beauty of the gypsum [selenite] 

crystals:

These are hexagonal-radiate, each division being a pinnate or 

feather-shaped lamina of twin rows of crystals. The clearness 

of the mineral and the regular leaf and feather forms of the 

crystals give them much beauty. The bones of vertebrate fossils preserved in this bed are often much injured by the 

gypsum formation which covers their surface, and often penetrates them in every direction.

At that time Cope (1872b) also briefly described 

another plesiosaur (Plesiosaurus gulo Cope, n. sp.) 

and the mosasaur Clidastes, collected "in close proximity near Sheridan, Kansas, by Joseph Savage of 

Leavenworth." Cope believed the plesiosaur had 

devoured the smaller mosasaur and mentioned that 

the bones were associated with a few fragments of 

a large turtle. The collection was not referred to any 

one formation, but later Cope (1875, p. 256) assigned the plesiosaur to the Niobrara. At that time, 

Cope (1875, p. 79-88) more thoroughly described 

his Elasmosaurus platyurus and remarked that it 

came from an "escarpment of a bluff of clay-shale 

rock, with seams and crystals of gypsum." Regarding the presence of fossil fish beneath the plesiosaur 

skeleton, Cope (1875, p. 79-80) stated that they 

consisted of "scales and teeth of some six species 

of Physoelyst and Physostomus fishes * * * including 

an Enchodus and a Phasganodus; the latter indicating a new species * * * called P. carinatus. These 

animals had doubtless been the food of the Elasmosaurus."

Although Cope mistook the Sharon Springs Member for the lower part of the "Niobrara division," 

Hayden apparently mistook the same beds for the 

Benton Group that underlies the Niobrara. In mentioning the occurrence of vertebrates, Hayden 

(1872, p. 68) remarked that "In [Formation] No. 2 

[Benton], not far from Fort Wallace, have been 

found, the remains of gigantic reptiles 40 or 50 

feet in length."

That the beds near Fort Wallace actually represented part of the Pierre was suggested by F. B. 

Meek in a letter to B.'F. Mudge (1877, p. 284). 

Mudge had collected from "a bed of Baculites" near 

Sheridan some well-preserved ammonites which he 

sent to Meek, who identified them as Baculites 

anceps Lamarck. Meek pointed out that this species 

was known only from rocks of post-Niobrara age 

and that, unlike the internal molds collected from 

the Niobrara, Mudge's specimens had the shell 

material preserved. Williston (1893, p. 110) later 

visited Mudge's locality and found "one or two other 

mollusks" that seemed to be Pierre types. The association of these and other invertebrates with a new

species of vertebrate, the mosasaur Clidastes westii 

Williston, that had been collected by C. H. Sternberg 

near Sheridan, had been documented previously in 

a paper by Williston and Case (1892, p. 29). Sternberg said the mosasaur came from the uppermost 

Niobrara beds, but Williston and Case (1892, p. 29) 

stated, "The character of the associated invertebrate 

fossils seems to indicate a different geological horizon, either the Fox Hills group, or transition beds to 

that group." In 1897, Williston, in discussing the 

Niobrara, pointed out that the Fort Pierre [Pierre 

Shale] had been "confounded with the Niobrara" 

by earlier collectors and that Clidastes westii and 

the baculites from Sheridan came from the Pierre. 

Sheridan was a terminus of the Kansas Pacific 

Railroad (now Union Pacific) in the early 1870's 

(Bardack, 1965, p. 10). Apparently, it was abandoned about 20 years later, as indicated by reference 

to it as "the old town of Sheridan" (Williston and 

Case, 1892, p. 29). Sometime in the 1890's the new 

town of Lisbon was approximately at the site of 

Sheridan (Bardack, 1965, p. 6). Cragin (1896, p. 

52) gave the name "Lisbon shales" to the beds now 

assigned to the Sharon Springs Member and the 

overlying Weskan Member. Cragin's description is 

brief:

Named from Lisbon, Kansas, near which they outcrop. 

Dark-bluish and brownish shales. Seen above the Smoky Hill 

chalk in Logan and Wallace Counties, Kansas and Elbert 

County, Colorado. Contains concretions of yellow phosphate of 

iron. * * * Supposed to be lower Ft. Pierre. Fossils: Inoceramus barabini, Baculites, limpets, etc.

Cragin's stratigraphic name seems to have been 

adopted only by Stewart (1899, p. 110; 1900, p. 

337), who described the new series of fish Empo 

lisbonensis, or Cimolichthys nepaholica (Cope) according to Goody (1970, p. 3), Protosphyraena 

gigas, and Pachyrhizodus as coming from the Lisbon 

shales near Lisbon. About that time, Wagner (1898) 

described a turtle (Toxochelys latiremis Cope) collected by S. W. Williston at Eagle Tail Creek near 

Sharon Springs and another specimen (Toxochelys 

aff. T. latiremis} from the Lisbon area. These 

specimens, which were said to have come from the 

"Fort Pierre," are from beds now assigned to the 

Sharon Springs Member. At that time, Adams 

(1898) presented a geologic map of Logan County 

in which the "Fort Pierre Shales" were mapped

with the Niobrara, but he noted that they «* * * may

be recognized by the blue shales and the concretions 

or septaria which they contained. It is typically 

exposed at McAlister [sicl." Darton (1905, p. 320) 

applied the name Pierre Shale to strata in Wallace 

County and estimated that about 300 feet was
GEOLOGIC SETTING

present in the Smoky Hill River valley east of 

Wallace.

During the interval 1906-27, nothing seems to 

have been published about the lower part of the 

Pierre Shale of western Kansas. In the period 

1928-30, interest in volcanic ash, cave-ins, and oil 

and gas possibilities in western Kansas created 

renewed interest in the Pierre. Pinkley and Roth 

(1928) mentioned bentonite beds in the lower part 

of the Pierre Shale and presented a photograph of 

one. Russell (1929, p. 599) observed that the basal 

400 feet of the Pierre Shale was divisible into five 

lithologic members, the contacts of which wej:e 

reliable marker horizons. He reported the lowest 

member to be a soft shale and the overlying member 

to be a hard fissile shale that weathered light 

brownish gray and contained septarian concretions. 

He gave no thicknesses, but these two units make up 

the present Sharon Springs Member. Elias (1930), 

in describing a cave-in along the Smoky Hill River 

near Sharon Springs, estimated that as much as 

350 feet of Pierre Shale was in the area and that 

the lowest part consisted of clayey shale intercalated with dark-gray calcareous shale.

Elias published his classic study of the Pierre 

Shale of Wallace County and adjacent areas in 1931. 

He divided the Pierre Shale into the following members, from oldest to youngest: Sharon Springs, 

Weskan, Lake Creek, Salt Grass, an unnamed member, and Beecher Island. He reported on cephalopods 

of the Pierre Shale in 1933.

Since Elias's work, few papers have been published about the Sharon Springs Member of western 

Kansas. Frye and Leonard (1949, p. 32-33) drew 

attention to outcrops of the lower part of the Pierre 

Shale northeast of the Wallace-Logan County area 

and near the Kansas-Nebraska boundary. Bradley 

and Johnson (1957, p. 20-22), Johnson (1958, p. 

41-43), and Hodson (1963, p. 16-18, 46-48) briefly 

described parts of the Sharon Springs Member in 

Wallace and Logan Counties in connection with 

studies of ground-water resources. Landis (1959) 

investigated the Sharon Springs in these counties 

for radioactivity and uranium content and measured 

several sections of parts of the unit.

Two large collections of Baculites asperiformis 

Meek from the McAllaster area were reported by 

Cobban (1962, p. 708-709, pi. 106). Each collection 

came from a separate limestone concretion in the 

upper part of the Sharon Springs Member. Specimens from one of the concretions, showing various 

growth stages, are shown on plate 2. A fragment of 

another ammonite, Trachyscaphites spiniger (Schliiter) subsp. porchi Adkins (pi. 2, fig. 12), was reported by Cobban and Scott (1964, p. E2, E3, E5, 

Ell) from one of the concretions.

David Bardack (written commun., 1965) of the 

University of Illinois recently collected an almost 

complete fish skeleton from the Sharon Springs 

Member of Kansas. This specimen, Pachyrhizodus 

minimus, was found at the type locality of the 

Sharon Springs Member in sec. 8, T. 12 S., R. 36 W.

GEOLOGIC SETTING

During Late Cretaceous time (CenomanianMaestrichtian), a broad epicontinental sea which 

extended from Mexico to the Arctic covered much 

of the western interior of the United States and 

Canada. The position of the western border of the 

sea fluctuated, apparently chiefly in response to 

tectonic and volcanic activity in the elevated land 

areas to the west. Most of the sediment delivered to 

the sea seems to have been derived from western 

source areas; the low-lying landmass that formed 

the eastern shore supplied but little detritus. Clastic 

materials in the form of sand, mud, and volcanic 

ash, represented by the Graneros, Carlile, and Pierre 

Shales and equivalent rocks, form most of the Upper 

Cretaceous rocks. Biogenic sediments of shallowwater origin, such as marlstone, chalk, and limestone, which make up the Niobrara and Greenhorn 

Formations as well as parts of the Pierre Shale in 

the Dakotas and Nebraska, constitute only a minor 

part of the total rock volume.

That numerous fluctuations of the western border 

of the sea occurred during the Cretaceous is evidenced by complex interfingering of marine and 

nonmarine deposits. Evidence of similar interfingering along the eastern margin of the sea has been 

largely obliterated by post-Cretaceous erosion. During three long periods of carbonate deposition in 

Late Cretaceous time, the Greenhorn Limestone, the 

Fairport Chalk Member of the Carlile Shale, and 

the Niobrara Formation were formed. These three 

deposits are westward-pointing wedges of calcareous 

sediments enclosed by eastward-pointing wedges of 

noncalcareous shales and sandy sediments.

During early Niobrara time (late Turonian and 

Coniacian), when the Cretaceous interior sea was 

at least 900 miles wide, conditions were favorable 

to the deposition and preservation of carbonates 

over an area from the eastern shoreline westward 

to eastern Utah, central Wyoming, and central Montana (fig. 2). The area of carbonate accumulation 

is thought to have been a shallow-water shelf that 

extended westward from the eastern shoreline for 

400-800 miles. By latest Niobrara time (early

459-596 O - 72 - 2
6 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Campanian), the western edge of the area of carbonate deposition had retreated 200 miles eastward 

to central Colorado and, farther north, 500 miles 

eastward into the eastern Dakotas (fig. 2). The 

eastward shift in the position of the western edge 

of the shallow-water carbonate accumulation was 

accompanied by an eastward migration of the deeper 

water depositional environment in which the organicrich shales of the Sharon Springs Member are 

assumed to have accumulated. That the organic-rich 

shales become progressively younger from west to 

east is shown by stratigraphic and paleontologic 

data from several widely separated areas.

The Niobrara Formation seems to reflect a broadscale westward expansion of the Cretaceous sea during the early part of its depositional history and a 

recession of the sea during the later part of its 

depositional history (fig. 2). Hattin (1966, p. 217) 

recognized the overall transgressive nature of the 

Niobrara but regarded the overlying Pierre Shale 

strata as the succeeding regressive depositional 

sequence. The upper part of the Niobrara Formation 

is equivalent to the Telegraph Creek Formation and 

to the Eagle Sandstone and equivalent beds in Montana, Wyoming, and Colorado; these rocks represent 

a widespread regression of the Cretaceous sea. The 

base of the Pierre Shale in Kansas, the Sharon 

Springs Member, is equivalent to the Claggett Shale 

of Montana. Their distribution demonstrates that 

the Claggett Shale and the Sharon Springs were 

deposited during the time of an expanding sea and 

should therefore be regarded as transgressive, 

rather than regressive, deposits.

STRATIGRAPHIC RESUME

NIOBRARA FORMATION

The name Niobrara Formation, of Late Cretaceous age (late Turonian-early Campanian), was 

given by Meek and Hayden (1861, p. 419, 422) to 

a 200-foot-thick sequence of yellowish-weathering 

marlstone and white limestone exposed along the 

Missouri River near the mouth of the Niobrara 

River in Knox County, Nebr. In western Kansas 

the formation is as much as 750 feet thick (Merriam, 1963, p. 45). It was divided by Mudge (1876, 

p. 214-219) into a lower member, the Fort Hays 

Limestone, and an unnamed upper member which 

was later called the Smoky Hill Chalk Member by 

Cragin (1896, p. 51).

Logs from oil and gas test wells in Wallace 

County indicate that the Fort Hays Limestone Member is about 60 feet thick and that the Smoky Hill

110 C 100°

40'

32'

Early Campanian

shelf carbonates V_^ /v.-^

Inferred shoreline'.

during late 

Coniacian time 

ARIZONA ' NEW'"'

500 MILES 

I

J.

Claggett Shale 

Eagle Sandstone 

Telegraph Creek 

Niobrara Formation

4

 =»sr^_

2

 i 

1 T

 =b^^°~ ______ 

-= 1 Carbonates

r

4'

Sharon Springs 

Member,

Niobrara 

Formation

Late Early 

Coniacian Santonian

Late Early 

Santonjan Campanian

FIGURE 2. Paleogeographic map showing the eastward migration of areas of shallow-water carbonate accumulation 

during latter part of Niobrara time (late Coniacian to early 

Campanian).

Chalk Member is about 660 feet thick. According 

to Elias (1931, p. 29), no more than the upper 100 

feet of the Smoky Hill Chalk Member is exposed 

in Wallace County. Hattin (1965, p. 62-64) 

described in detail an 85-foot-thick sequence in the 

upper part of the Smoky Hill Member in the southern part of Logan County. This section did not 

extend as high as the Pierre-Niobrara contact, but 

it is thought to represent most of the upper part of 

the Niobrara Formation exposed in that area.

The upper part of the Niobrara Formation is 

composed of thin to thick beds of marlstone, shaly 

chalk, and chalk which is bluish gray to lead gray in 

fresh exposures but which weathers white or to 

shades of yellowish gray and orange. The contact 

between the Niobrara and the overlying Pierre is 

ordinarily difficult to determine in fresh exposures, 

inasmuch as the two formations are similar in color 

and beds characteristic of each formation appear to
STRATIGRAPHIC RESUME

alternate with each other. Locally, the basal part 

of the Pierre contains a transitional unit in which 

dark beds of calcareous shale are interbedded with 

dark beds of noncalcareous shale. We placed the 

contact at the horizon dividing the dominantly calcareous rocks below from those that are dominantly 

noncalcareous above. The use of acid is helpful as 

a test in locating the contact, although calcareous 

shales in the lower part of the Pierre can also be 

recognized by the minute white or light-gray calcareous specks they contain. The precise contact 

between the two formations is also difficult to determine from test-hole cuttings (Iocs. 2, 6), but electric 

and gamma-ray logs are of considerable assistance. 

The contact between the Pierre and Niobrara Formations is pinpointed on the electric log at the sharp 

downward increase in resistivity and decrease in 

the self potential (fig. 17) changes which apparently reflect the transition from the noncalcareous 

rocks of the Pierre to the dominantly calcareous 

rocks of the Niobrara.

PIERRE SHALE

SHARON SPRINGS MEMBER

The name Sharon Springs Member of the Pierre 

Shale was applied by Elias (1931, p. 58-65) to 

exposures in Logan and Wallace Counties that consist of an upper hard buttress-weathering black 

shale containing abundant fish scales and bones and 

a lower softer dark-gray flaky shale. A complete 

section of the member is not known to be exposed 

in western Kansas, but fieldwork, supplemented by 

drilling, indicates that the member is about 225 

feet thick. The Sharon Springs Member conformably 

and transitionally overlies the Niobrara Formation. 

The Weskan Member of the Pierre conformably 

overlies the Sharon Springs, the contact being 

marked by an abrupt change upward from hard 

slightly phosphatic shale which contains abundant 

organic material and numerous layers of phosphate 

nodules to a soft shale which contains many thin 

bentonite beds. Elias (p. 62) originally included a 

bed of "large lenslike bodies of light-gray to yellowish-white laminated limestone" at the top of the 

Sharon Springs. This concretionary limestone is 

unlike septarian limestone concretions in the underlying part of the Sharon Springs Member; it is more 

like limestone concretions in the Weskan Member. 

Furthermore, the concretionary limestone bed contains the kind of fossils that is in the lower part 

of the Weskan Member. For these reasons, we 

exclude this bed from the Sharon Springs and make 

it part of the Weskan Member.

The type locality for the Sharon Springs Member 

designated by Elias (1931, p. 63-64) is about 2 

miles east of McAllaster Buttes near the abandoned 

town of Lisbon (fig. 1), apparently in about the 

center of sec. 8, T. 12 S., R. 36 W., Logan County, 

Kans. The name was derived from the town of 

Sharon Springs, the Wallace County seat.

In areas outside Kansas, the name Sharon Springs 

has been used widely for rocks that are similar in 

stratigraphic position and lithology (fig. 3). In 

1937, the Sharon Springs was recognized by Dane, 

Pierce, and Reeside (1937, p. 225) as a member of 

the Pierre Shale in eastern and southern Colorado, 

where the name was applied to rocks formerly called 

the Barren zone by Gilbert (1897). Griffitts (1949, 

p. 2012, 2015) applied the name Sharon Springs to 

dark-gray shales overlying the Niobrara Formation 

east of the Front Range in central and northern 

Colorado, and LeRoy and Schieltz (1958) described 

a number of sections of the Sharon Springs that 

extended along the Front Range from Canon City 

to near the Colorado-Wyoming boundary. The 

Sharon Springs equivalent extends into the Book 

Cliffs area of western Colorado and Utah where it 

is lithologically distinctive in the upper part of the 

Mancos Shale. Recently the Sharon Springs Member 

of the Pierre Shale was formally recognized in the 

Middle Park area near Kremmling, Colo. (Izett and 

others, 1971).

In 1938, Searight (p. 137) applied the name 

Sharon Springs to hard black shales at the base of 

the Pierre along the Missouri River in central South 

Dakota, and a year later he used the name for 

similar strata around the Black Hills in western 

South Dakota and southeastern Wyoming (Moxon 

and others, 1939, p. 20-21). It is interesting to note 

that in 1931 Elias had suggested a similar correlation of the Sharon Springs Member in Colorado 

and South Dakota. Condra and Reed (1943, p. 17) 

applied the name to the lowermost part of the 

Pierre in Nebraska.

WESKAN MEMBER

Elias (1931, p. 77-88) described the Weskan 

Member as a 170-foot-thick sequence of dark-gray 

unctuous shale that contains abundant thin bentonite beds and limestone and ironstone concretions. 

The type locality for the Weskan Member is along 

the bank of a small creek in the SE^i sec. 2, T. 13 S., 

R. 42 W., Wallace County, Kans. The member, 

named for the town of Weskan in west-central Wallace County, can be divided into a lower unit about 

90 feet thick and an upper unit about 80 feet thick.
THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

in

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ammonite zones

Baculites clinolobatus

Baculites grandis

Baculites baculus

Baculites eliasi

Baculites jenseni

Baculites reesidei

Baculites cuneatus

Baculites compressus

Didymoceras cheyennense

Exiteloceras jenneyi

Didymoceras stevensoni

Didymoceras nebrascense

Baculites scotti

Baculites gregoryensis

Baculites perplexus 4

Baculites sp. (smooth)

Baculites asperiformis

Baculites mclearni

Baculites obtusus

Baculites sp. 

(weakly ribbed)

Baculites sp. (smooth)

Scaphites hippocrepis

Millions of years '

Estimated age

70 

71 

72 

73 

74 

75

76 

77 

78

79 

80 

81

Potassium-argon 

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2 Dunham (1961).

3 J. D. Obradovich (written commun., 1968).

4 This zone, which includes 1,000 ft. of Pierre Shale in eastern Wyoming, is divisible 

into an early and late form of Baculites perplexus, separated by B.gilberti.

FIGURE 3. Time span of the Pierre Shale in western Kansas and equivalent rocks in nearby States.
STRATIGRAPHIC RESUME 9

South Dakota

Chamberlain 

area

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Virgin Creek 

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Verendrye 

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Crow Creek 

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Sharonprings Member

Gregory 

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Wyoming

Red Bird

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Silty 

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Mitten 

Black Shale 

Member

Sharon 

Springs 

Member

Gammon

Ferruginous 

Member

Niobrara 

Formation 

(part)

Montana

Central

Hell Creek 

Formation (part)

Fox Hills 

Sandstone

Bearpaw 

Shale

-

Judith River 

Formation

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Claggett 

Shale

Eagle 

Sandstone

The lower unit contains numerous bentonite beds, 

one of which is at least 1 foot thick. Large fossiliferous gray- and brown-weathering limestone and 

purple-brown-weathering ironstone concretions,

common in the lower unit of the Weskan, are not as 

abundant in the upper unit. The base of the Weskan 

is marked by long light-gray-weathering fossiliferous limestone lenses as much as 1 foot thick and 50 

feet across. These, were regarded by Eli as (p. 62) 

as the top of the Sharon Springs Member.

The upper unit of the Weskan Member contains 

three conspicuous zones of large gray limestone 

concretions and two zones of purple-brown-weathering ironstone concretions. Locally, there are irregular masses of cavernous "tepee butte" limestone, 

which contains many pelecypods. Limestone concretions in the upper unit have a fairly large and 

diverse marine fauna. The shale in this part of the 

member contains many thin bentonite layers, none 

of which is more than 1 inch thick. The Weskan 

Member is conformably overlain by the Lake Creek 

Member and, in the Weskan, the contact is marked 

by one or more layers of closely spaced dark-gray 

compact limestone concretions that locally form 

ledges.

To date (1971) the name Weskan has been applied 

only to rocks in western Kansas, but the member 

can be recognized in the Pierre Shale of eastern 

Colorado where the name could appropriately be 

used. The Weskan is equivalent to most of the 

Tepee zone of Gilbert (1897, p. 3) in the Pueblo 

area of Colorado and to the Terry Sandstone Member of the Pierre Shale and part of the underlying 

and overlying unnamed shale members near Fort 

Collins, Colo. In the area of the type Pierre Shale 

along the Missouri River in central South Dakota, 

the Weskan is equivalent to the upper part of the 

Gregory Member, the Crow Creek Member, and 

the lower two-thirds of the DeGrey Member. The 

limestone concretion layer that forms the base of 

the Weskan contains poorly preserved inocerams 

and ammonites that suggest the zone of Baculites 

gregoryensis Cobban. The upper unit of the Weskan 

contains Inoceramus vanuxemi Meek and Hayden, 

Placenticeras meeki Boehm, and other fossils. (For 

a more complete list of fossils, see Elias, 1931, p. 62, 

78, 93.) Near Wild Horse, Colo., gray limestone 

concretions, believed to be in the upper unit of the 

Weskan Member, contain a baculite that has the 

conspicuous ventral ribbing associated with Inoceramus vanuxemi. This association suggests the zone 

of Didymoceras cheyennense (Meek and Hayden) 

for that part of the member.

LAKE CREEK MEMBER

The name Lake Creek Member of the Pierre Shale 

was applied by Elias (1931, p. 93) to a 200-footthick sequence of dark-gray and black flaky shale
10 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

containing ironstone concretions that is exposed 

along Lake Creek in northwestern Wallace County. 

The name Lake Creek has been used only in Wallace 

County, but it could be used equally well elsewhere 

in western Kansas and eastern Colorado. The 

sparseness of large limestone concretions distinguishes the Lake Creek Member from the overlying 

Salt Grass and underlying Weskan Members.

In addition to numerous small ironstone concretions, the Lake Creek Member contains many thin 

layers of concretionary limonite associated with 

small yellowish-white or light-gray limestone or 

marl concretions. The soft limy concretions are less 

than 0.1 foot thick and are unlike the large hard 

limestone concretions of the contiguous members. 

Lower and middle parts of the member contain 

numerous Baculites reesidei Elias. The upper part 

of the member has yielded B. reesidei at some localities and B. jenseni Cobban at others. (For a more 

complete list of invertebrate fossils, see Elias, 1931, 

p. 95.)

In east-central Colorado, the Lake Creek Member 

equivalent is the Larimer and Rocky Ridge Sandstone Members of the Pierre Shale (fig. 3) and the 

upper two-thirds of the unnamed sandstone and 

shale member that underlies them. The Lake Creek 

is also equivalent to about the lower three-fourths 

of the Verendrye Member of the type Pierre Shale 

in central South Dakota. Beds equivalent to the 

lower two-thirds of the Lake Creek are missing in 

the Black Hills area and in eastern Wyoming (Gill 

and Cobban, 1966a).

SALT GRASS MEMBER

The name Salt Grass Member of the Pierre Shale 

was given by Elias (1931, p. 101) to exposures of 

gray clayey shale in Salt Grass Canyon, the southern 

tributary to Goose Creek in sees. 1 and 12, T. 12 S., 

R. 42 W., Wallace County, Kans. The shale of this 

member is lighter than the dark-gray to black shale 

of the conformably underlying Lake Creek Member. 

The Salt Grass Member, about 60 feet thick, is 

divisible into three units, the lowest of which contains large fossiliferous limestone concretions and 

masses of tepee-butte limestone. The middle unit 

contains many layers of concretionary limonite, and 

the upper unit contains well-developed ledge-forming concretions with cone-in-cone structure. Baculites reesidei and B. jenseni are in the basal beds, 

and abundant B. eliasi Cobban are in the middle 

unit. Numerous other marine invertebrates found 

in the member have been listed by Elias (p. 102- 

104).

UNNAMED MEMBER

Overlying the Salt Grass Member of the Pierre 

Shale is a 500- to 600-foot-thick unit of gray and 

black shale that is only partly exposed in Wallace 

County and poorly exposed elsewhere in western 

Kansas. Elias (1931, table opposite p. 58) studied 

only the lower 30 feet and the uppermost exposed 

90 feet of the member. The distribution, lithology, 

and fossil content of this member are largely unknown in western Kansas and eastern Colorado.

BEECHER ISLAND MEMBER

The Beecher Island Member, designated the uppermost unit of the Pierre Shale in western Kansas 

and eastern Colorado by Elias (1931, p. 123-124), 

consists of about 100 feet of light-gray shale that, 

being transitional between the clay shale of the 

Pierre and the sandy beds of the overlying Fox Hills 

Sandstone, is somewhat silty or sandy. It is exposed 

along the Arikaree River near the town of Beecher 

Island in southeastern Yuma County, Colo. The 

member is also exposed along the Arikaree River 

in Cheyenne County, Kans., where Cragin (1896, 

p. 52) long ago applied the name "Arickaree shales" 

to it. The member conformably overlies the unnamed shale member and is conformably overlain by 

the Fox Hills Sandstone.

The lower part of the member contains gray fossiliferous silty limestone concretions that weather 

yellowish gray, and the upper part of the member 

contains thin layers of limonite, rusty-weathering 

limestone, and concretions having cone-in-cone 

structure. The Beecher Island contains Baculites 

grandis Hall and Meek in the lower part and B. 

clinolobatus Elias in the upper part, in addition to 

Tenuipteria fibrosa (Meek and Hayden) and species 

of Discoscaphites and Hoploscaphites. A complete 

list of fossils in the Beecher Island Member is in 

Elias (1931, p. 130).

SHARON SPRINGS MEMBER

The type locality for the Sharon Springs Member 

is in western Logan County. Regarding this locality, 

Elias (1931, p. 63-64) stated: "The section of the 

Sharon Springs member that was originally studied 

by the writer and set apart from the rest of the 

Pierre shale lies east of McAllaster station in Logan 

County. On a left tributary to Smoky Hill river, 

about 2 miles east of McAllaster buttes * * *." The 

name of the member was taken from the town of 

Sharon Springs, in the center of Wallace County, 

about 25 miles southwest of the type locality.
SHARON SPRINGS MEMBER 11

The lithology of the Sharon Springs is different 

from that of the rest of the Pierre Shale, a fact 

which led Elias to give the Sharon Springs formal 

member status. He (1931, p. 58-59) described it 

as follows:

The member consists of black, slightly bituminous shale, with 

which is interbedded dark-gray shale in the lower portion and 

about in the middle of the member. The shale is full of the 

remains of small fishes, which were probably the source of the 

bituminous matter in it. The small scales and bones of fishes 

can be detected in nearly every piece of the black shale. The 

Sharon Springs member can be conveniently subdivided into 

Upper and Lower Sharon Springs. The Upper Sharon Springs, 

which is about 65 feet thick, can be recognized by the abundance of concretions, many very large (pi. V), whereas in the 

Lower Sharon Springs the concretions, none of which are 

large, are very scarce and in many places practically absent. 

The shale of the Upper Sharon Springs is also somewhat different from that of the Lower Sharon Springs. Some beds of 

the former resist weathering more than the ordinary shale 

of the formation and appear as slightly prominent bands in 

the outcrops.

For the present investigation a threefold division 

of the Sharon Springs is recognized (fig. 4). In this 

report, the lower unit, about 115 feet of dominantly 

dark-gray soft flaky shale having a few concretions 

of yellow chalky limestone, is referred to as the 

"dark soft shale unit." The middle unit, called the 

"organic-rich shale unit," consists of about 90 feet 

of hard buttress-weathering shale, is rich in organic 

material and in varied limestone concretions, and 

has yielded abundant vertebrate and a few invertebrate fossils. The upper unit, about 10 feet of 

hard-platy-weathering slightly phosphatic shale that 

contains numerous layers of soft highly weathered 

phosphate nodules, is referred to as the "phosphatic 

shale unit."

DARK SOFT SHALE UNIT

The most complete exposure of the lower unit of 

the Sharon Springs Member is along the west 

valley wall of Burris Draw (loc. 1) about 4 miles 

southwest of Elkader. At this locality, the contact 

between the Sharon Springs and the Smoky Hill 

Chalk Member of the Niobrara Formation is well 

exposed (fig. 5), and approximately 90 feet of the 

lower unit of the Sharon Springs Member can be 

measured (fig. 6). The lower unit consists largely 

of light- to medium-gray, light-olive-gray, and black 

shale and, near the top, contains a thin dark-yellowish-orange chalky concretionary layer. As a result 

of pre-Tertiary(?) oxidation and weathering, certain layers in the shale were altered from various 

shades of gray to dark yellowish orange, causing 

the upper part of the exposure to appear banded. 

The shale is soft and weathers readily to a deep soil 

which obscures the bedrock.

At localities 1, 4, and 5 the lower unit of the 

Sharon Springs Member contains some thin beds of 

hard buttress-weathering organic-rich shale (measured sections, and figs. 4, 5, and 7) that is quite 

similar to the overlying organic-rich shale unit. It 

is quite possible that, if these hard shales could be 

traced westward, they would be found to be tongues 

of the overlying unit. Thin persistent bentonite beds 

are also characteristic of the lower unit of the 

Sharon Springs in many areas outside western 

Kansas. At the Burris Draw section (loc. 1) there 

are only four thin bentonite beds, whereas 30 miles 

to the northwest at locality 5, there are nine beds, 

some as much as 1 foot thick, in the lower 20 feet 

of the unit. (See measured sections.) The lower unit 

of the Sharon Springs Member is in northern 

Phillips County, Kans., where about 55 feet of dark 

soft shale is interbedded with 14 thin nonswelling 

bentonite beds which appear as light bands on the 

outcrop (fig. 8) and range in thickness from an inch 

or two to about half a foot. The few fossils from 

concretions, which are sparse in the lower unit of 

the Sharon Springs, indicate that this unit was 

deposited during the range of the ammonites Baculites sp. (weakly ribbed) and Baculites obtusus (fig. 

3 and pi. 1). B. obtusus is in the organic-rich shale 

unit at several localities along the Front Range in 

Colorado and around the Black Hills in eastern 

Wyoming and western South Dakota. Its presence 

in shales that are rich in organic matter in western 

areas and below shales that are rich in organic matter in eastern areas, such as western Kansas, clearly 

indicates that deposition of the organic-rich shale 

unit began earlier in the western areas and that the 

organic-rich shale unit decreases in age from west to 

east (fig. 9). Subsurface studies in the Great Plains 

permit delineation of the western edge of the organicrich shale unit, which was deposited during the range 

of B. obtusus. Figure 10 shows the inferred position 

of the shoreline during the range of B. obtusus and 

the western edge of the organic-rich shale unit. At 

present, the eastern limit of this unit cannot be accurately determined, but stratigraphic and f aunal data 

indicate that it was somewhere in eastern Colorado. 

The dark soft shale unit grades laterally into and 

intertongues with the organic-rich shale unit toward 

the west and northwest.

ORGANIC-RICH SHALE UNIT

Approximately 90 feet of dark-brownish-black organic-rich shale containing abundant layers of closely 

spaced limestone concretions of various shapes and 

sizes constitutes the middle unit of the Sharon
12 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Springs Member in Wallace and Logan Counties. 

The organic material in the shale, which consists 

largely of macerated fish scales and bones, may also 

have been partly derived from marine and terrestrial 

plants. This unit of the Sharon Springs Member is 

best and most completely exposed on the north face 

of McAllaster Buttes. Other good exposures are 

about 1.5 miles north of McAllaster Buttes, about 

2 miles northeast of McAllaster near the abandoned 

towns of Lisbon and Sheridan (fig. 1), and at Devils 

Half acre (loc. 6) southeast of the town of Sharon 

Springs.

The organic-rich unit is harder and resists weathering to a greater degree than the upper or lower 

units. It contains on the average about 4.9 percent 

organic carbon, and some beds near the top contain 

as much as 9.6 percent (table 1). Though test-hole 

cuttings from the phosphatic shale unit contain less 

than 1 percent organic carbon, selected outcrop samples contain about 6 percent, and the organic-rich 

shale unit has an average organic-carbon content of 

3.8 percent. Shales high in organic carbon are darker 

than those low in organic carbon and are more resistant to erosion, weathering to tough papery flakes. 

They contain large amounts of jarosite, limonite, and 

gypsum, minerals that coat joint surfaces and bedding planes and are thought to be the weathering 

products of pyrite. Some gypsum crystals in the 

upper part of the unit form interlocking rosettes as 

much as 1 foot in diameter (fig. 1). These rosettes 

were noted by Cope (1872a, p. 326), and those from 

the McAllaster area, by Elias (1931, pi. 13, figs. B, 

C) and Tolsted and Swineford (1957, p. 40).

The upper part of the organic-rich shale unit contains numerous layers of closely spaced limestone 

concretions. Some of the concretions are irregular 

in shape and are composed of dense dark-gray to 

black limestone (fig. 12). These concretions weather 

light gray to white, are nonfossiliferous, and are so 

hard that they can be broken only with great difficulty. They are characteristic of the organic-rich 

shale unit in Kansas, Colorado, southeastern Wyoming, and western South Dakota. Gigantic septarian concretions, also characteristic of the Sharon 

Springs at many localities, crop out about 20 feet 

below the top of the unit. These concretions, which 

are closely spaced and form ledges, are as much as 

3 feet thick and at least 20 feet in diameter and have 

internal fractures that are almost completely filled 

with dark-brown fibrous calcite (fig. 13). Bluishgray barite is in these and other septarian concretions near the top of the unit. Barite crystals from 

this area were first reported by LeConte (1868, p. 

11). Mudge (1876, p. 215) mentioned a rich-ambercolored barite crystal weighing 8*4 pounds that had 

been collected from the unit near the old town of 

Sheridan. Elias (1931, p. 61) noted, "A rare transparent variety of the local barite is of beautiful 

wine-brown color." Ovate to spherical septarian concretions are found near the top of the organic-rich 

shale unit. Fractures in these concretions are not 

completely filled but generally contain a thin lining 

of fibrous calcite coated with pale-yellow to transparent calcite crystals and, rarely, bluish-gray barite 

crystals. Limestone with cone-in-cone structure is 

common in the unit and occurs as flat tabular masses 

(fig. 14) and as rinds or envelopes which enclose 

septarian limestone concretions.

LOCALITY 6

SWi/4SEi/4NW1/4 sec. 36, T. 13 S., R. 40 W. 

Wallace County, Kan.

Guy Holland I 

State test hole

Self-potential Depth Resistivity 

curve (feet) curve

Surface section

Phosphatic 

shale unit

-D1176

Organic-rich 

E- 50} shale unit

Niobrara 

Formation (part)

FIGURE 4. Graphic sections and electric
ORGANIC-RICH SHALE UNIT 13

Thin persistent pale-yellowish-gray nonswelling 

bentonite beds are in the upper part of the organicrich shale unit. The nonresistant character of the 

bentonite, because it contrasts sharply with the resistance of the enclosing hard shale, gives the outcrop (fig. 15) a stairstep form.

The organic-rich shale unit contains fish bones and 

scales and the remains of large marine reptiles, but 

it does not contain many invertebrate fossils that 

are useful for correlation. Though megafossils are 

rare, two discoveries are spectacular. In the section 

at McAllaster Buttes, a gray limestone concretion 

(USGS Mesozoic loc. D2951) about 1 foot thick 

and 6 feet in diameter yielded 1,553 specimens of

Baculites asperiformis Meek which are 2-37 mm 

(millimeters) in diameter. A limestone concretion 

of similar size 3 miles southwest of McAllaster 

yielded 1,597 specimens of B. asperiformis which 

are 0.9-33.5 mm in diameter.

The unit was probably deposited during the ranges 

of Baculites mclearni and B. asperiformis; only B. 

asperiformis is in collections from western Kansas 

(pi. 2). Figure 16 shows the inferred position of the 

shoreline and the inferred west edge of the organicrich shale unit during the range of B. asperiformis.

On electric logs the organic-carbon content of the 

Sharon Springs is reflected by a marked increase 

in the electrical-resistivity and electrical-induction

EXPLANATION

Soft flaky-weathering shale

FEET 

O-i

ID20- 

30- 

40-

Organic-rich buttress-weathering shale

Calcareous shale and marlstone

CONCRETIONS

Limestone

© 

Septarian limestone

t£t 

Limestone and cone-in-cone

Ironstone

Phosphate nodules

D2591 

USGS Mesozoic fossil locality

LOCALITY 5

SEi/4NEy, sec. 32, T. 13 S., R. 37 W. 

Logan County. Kan.

LOCALITY 2

SEy4 sec. 13, T. 12 S. r R. 37 W. 

Logan County, Kan.

Phosphatic 

shale unit

Organic-rich 

shale unit

LOCALITY 3

SEV« sec. 20, T. 12 S., R. 36 W. 

Logan County, Kan.

-D2690 LOCALITY 1

NEi/4NEy4 sec. 20, T. 15 S., R. 32 W. 

Logan County, Kan.

LOCALITY 4

SW%SEV4 sec. 33, T. 12 S., R. 36 W. 

Logan County, Kan.

^=-01827

^r -D2691

Dark soft 

shale unit

-D5510

Niobrara 

Formation (part)

-8.7 MILES - -2.5 MILESlog of Sharon Springs Member of Pierre Shale in Wallace and Logan Counties, Kans.

459-596 O - 72 - 3
14 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

curves and by a similar but greater response on the 

gamma-ray curve. The electric and gamma-ray log 

cross section (fig. 17) shows the subsurface correlation of the Sharon Springs Member from Wallace 

County, Kans., to Fall River County, S. Dak. Fossils 

indicate that lines bounding units of high radioactivity and resistivity in the Sharon Springs Member are not time-stratigraphic markers. In western 

Kansas, for example, Baculites obtusus (pi. 1) is in 

the dark soft shale unit of the Sharon Springs, and 

B. asperiformis (pi. 2) is in the organic-rich shale 

unit of the member. Along the Front Range in central Colorado, and around the Black Hills in eastern 

Wyoming and western South Dakota, B. obtusus is 

restricted to the organic-rich shale unit of the Sharon 

Springs, and B. asperiformis occurs in younger beds 

which are not typical of Sharon Springs lithology 

(Gill and Cobban, 1966b, pi. 2). Because organic-rich 

shale typical of the Sharon Springs was deposited in 

the Colorado-Wyoming-South Dakota area earlier 

(Range Zone of B. obtusus) than in Kansas, the

organic-rich shale unit must become younger in an 

easterly and southeasterly direction (fig. 9).

PHOSPHATIC SHALE UNIT

The phosphatic shale unit of the Sharon Springs 

Member, which conformably overlies the organic-rich 

shale unit, consists of 10-13 feet of dark-brownishblack to grayish-brown shale that contains as many 

as 10 thin layers of dark-bluish-gray- to yellowishgray-weathering phosphate nodules. The shale is 

moderately hard, contains fish scales and bones, and 

weathers into irregular plates that, together with 

the phosphate nodules, litter the outcrop. It also contains several thin pale-yellow- to orange-weathering 

nonswelling bentonite beds (fig. 18). The unit is 

overlain by a 1-foot-thick bed of shaly to laminated 

concretionary limestone (fig. 19) which was regarded 

as the top of the Sharon Springs Member by Elias 

(1931, p. 62) but is placed in the overlying Weskan 

Member by us.

FIGURE 5. Contact of Sharon Springs Member (above) of Pierre Shale and Smoky Hill Chalk Member (below) of Niobrara

Formation exposed in Burris Draw (loc. 1).
PHOSPHATIC SHALE UNIT 15

The upper part of the phosphatic shale unit contains some thin brownish-gray shale beds that 

weather light gray to white and that are very porous 

and light in weight (specific gravity about 1.4). 

Elias (1931, p. 59), describing this peculiar shale at 

considerable length, remarked,

Another kind of shale, which somewhat resembles the softer 

samples of Mowry shale of the Graneros and is remarkably 

light in weight, appears locally in slightly prominent bands 

near the top of the Upper Sharon Springs. This shale is light 

gray to nearly white when much weathered, and is porous 

and unpleasant to touch, not being "soapy" like the ordinary 

Pierre shale, but somewhat "chalky." However, no calcium 

carbonate or dolomite could be detected in this rock.

Samples of this shale contain slightly more than 1.5 

percent P2Os, which apparently accounts for some of 

the peculiar properties of the shale.

Elias (1931, p. 61) described the phosphate nodules in the upper part of the unit as concentric 

concretions that are "* * * nearly spherical and are 

composed of calcite, rusty limonite, gypsum and soft, 

rotten shale. They are fragile and usually have the

outer crust made up of gypsum and this crust filled 

with rotten shale * * *." The concretions are much 

as Elias described them (fig. 20) except that, instead 

of being cores of rotten shale, they are highly weathered phosphate nodules. Sawed surfaces (fig. 21) of 

the nodules show pronounced concentric bands of 

light and dark phosphatic material. The outside of 

the nodule consists of concentric layers of white gypsum and dark clay containing about 0.15 percent 

P2O5 , as determined volumetrically by G. D. Shipley 

of the U.S. Geological Survey. The inner light-brown 

bands contain about 0.9 percent P2O5 , and the darkbrown core, about 2.6 percent. Fresh phosphate nodules are dark brown to brownish black, weather 

bluish gray, and contain as much as 16 percent P2O5 . 

The phosphate nodules generally occur in thin 

layers separated by a few inches of shale; this bedding suggests slow uniform deposition. Locally, as 

in the SW*4 sec. 1, T. 12 S., R. 37 W., Logan County, 

bottom currents have eroded preexisting layers of 

phosphate nodules and concentrated them as lenslike masses of phosphate pebble conglomerate. The

FIGURE 6. Outcrop of dark soft shale unit of Sharon Springs Member of Pierre Shale exposed along west side of Burris

Draw (loc. 1).
16 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

origin of the phosphate nodules and phosphatic shale 

is unknown; however, the shale seems to have accumulated very slowly, in contrast with the rest of 

the Sharon Springs Member and the Pierre Shale as 

a whole. This interpretation is in general agreement 

with that of Goldman (1922) on the significance of 

phosphate-rich beds.

The phosphatic shale unit is conformably overlain 

by soft bentonitic shale of the Weskan Member of 

the Pierre Shale (figs. 19, 22). At most localities 

the contact is marked by a layer of shaly to laminated light-gray-weathering limestone concretions. 

At Devils Half acre, locality 6 (see measured section) , a 0.2-foot-thick bed of gypsum and soft white 

basaluminite (2A12O3 'SO3 * 10H2O) marks the contact between the two members.

RATE OF SEDIMENTATION

Fossils from the Sharon Springs Member in western Kansas and elsewhere in the western interior 

indicate that the member was deposited during the 

range of eight ammonite zones. In western Kansas 

the dark soft shale unit of the Sharon Springs Member is about 115 feet thick and contains the Range 

Zones of Baculites sp. (weakly ribbed) and B. obtusus. The organic-rich shale unit is about 90 feet 

thick and contains the Range Zones of Baculites 

mclearni and B. asperiformis. The phosphatic shale 

unit, which is approximately 10 feet thick, is represented by the range zones of the following fossils : 

A smooth unnamed baculite, an early form of B. 

perplexus, B. gilberti, and a late form of B. perrM$&£^-: '-''\» \:*'

FIGURE 7. Hard buttress-weathering shale rich in organic material, fish scales, and bones in lower unit of Sharon Springs 

Member of Pierre Shale at locality 1. Hammer marks position of a 0.2-foot-thick yellowish-gray nonswelling bentonite bed.
RATE OF SEDIMENTATION 17

FIGURE 8. Northeasternmost outcrop of Sharon Springs Member of Pierre Shale in Kansas. Exposed along east bank of 

Prairie Dog Creek about 1 mile east of town of Long Island in the E%SE% sec. 24, T. 1 S., R. 20 W., Phillips County, 

Kans. Contact with Niobrara Formation is near water level. Light bands on outcrop are bentonite beds.

plexus. In a previous investigation, we concluded 

that each of the above ammonite zones represents 

about 500,000 years (Gill and Cobban, 1966b, p. 

A36). If a similar relationship of ammonite zones 

to time is applicable to this area, about 4 million 

years was required to deposit the type Sharon Springs 

Member. On the basis of the number of ammonite 

zones, this figure can be broken down to 1 million 

years for the deposition of the dark soft shale unit,

1 million years for the organic-rich shale unit, and

2 million years for the phosphatic shale unit. Depositional rates would then be 115 feet per million years 

(35 mm per 1,000 yr) for the lower unit of the 

Sharon Springs Member, 90 feet per million years 

(27 mm per 1,000 yr) for the middle unit, and 5 feet

per million years (about 1.5 mm per 1,000 yr) for 

the upper unit.

Ammonite Range Zones Front Range (Colorado) Western Kansas

FIGURE 9. Diagram showing eastward and upward migration of organic-rich shale unit of Sharon Springs Member 

of Pierre Shale.
18 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

110° 100°

40'

32'

 t^

\

_ __CANADA _____ 

.NITEDT STATES~~~

| NORTH 

| DAKOTA

SOUTH 

DAKOTA 

Western 

edge of 

organic-rich" 

shale

NEBRASKA

o Sharon Springs 

KANSAS

_1_.

_____I TEXAS

fco T

500 MILES 

_I

FIGURE 10. Paleogeographic map of early stage of deposition of Sharon Springs Member of Pierre Shale (range 

of Baculites obtusus, late early Campanian), showing western edge of organic-rich shale unit.

FIGURE 12. Irregularly shaped light-gray-weathering concretions of dense dark-gray limestone from upper part of 

organic-rich shale unit at McAllaster Buttes (loc. 2).

FIGURE 11. Gypsum rosettes from upper part of organicrich shale unit of Sharon Springs Member of Pierre Shale 

at McAllaster Buttes. Rule is 7 inches in length.

FIGURE 13. Large ledge-forming septarian limestone concretions about 20 feet below the top of the organic-rich shale 

unit of Sharon Springs Member in vicinity of McAllaster 

Buttes. These concretions contain thick septa of light-brown 

fibrous calcite and have a botryoidal lower surface and a 

flat or concave upper surface. Locally they are more than 

3 feet thick and 20 feet in diameter.
SHARON SPRINGS MEMBER 19

FIGURE 14. Tabular bed of cone-in-cone limestone in upper part of organic-rich shale unit of Sharon Springs Member of

Pierre Shale at McAllaster Buttes.

100 C

FIGURE 15. Contact of phosphatic shale unit with organicrich shale unit of Sharon Springs Member of Pierre Shale 

at Devils Half acre (loc. 6). Contact is at the top of a 0.4- 

foot-thick bentonite bed which is second from the top of six 

bentonite beds visible in the center of the photograph. 

Upper slope of outcrop is littered with plates of hard phosphatic shale and nodules of phosphate.

500 MILES

FIGURE 16. Paleogeographic map of late stage of deposition 

of Sharon Springs Member of Pierre Shale (early late 

Campanian) showing eastward shift of west edge of the 

organic-rich shale unit.
20 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

S. DAK.

Samuel Gary I State

Center SEV4SEV4 sec. 25, T. 10 S., R. 5 E.

Fall River County, S. Dak.

KANS.

Sohio Petro. 18 State

NWViNWViNEVi sec. 34 T. 8 N., R. 5 W.

Logan County, Colo..

Spontaneous 

Gamma ray potential Raymond Oil Co. 1 Sides

Center NEViSWVi sec. 11, T. 34 N., R. 52 W

Sioux County, Nebr.

Mitten 

Black 

Shale 

Member 

(part)

Spontaneous DePtn 

potential (feet> Resistivity

Sharon Springs 

Member

Gammon Ferruginous 

Member

Southwestern South Dakota Northern Nebraska Northwest Colorado 

FIGURE 17. Electric and gamma-ray log correlation of Sharon Springs

Figure 23 shows diagrammatically the thickness 

and time relationship between the Sharon Springs of 

western Kansas and time-equivalent rocks in Colorado and Wyoming. If the upper unit of the type 

Sharon Springs Member was deposited at a rate of 

5 feet per million years, time-equivalent strata at 

Pueblo, Colo., and at Red Bird, Wyo., were deposited, 

respectively, 20 and 100 times as rapidly.

The lower and middle units of the Sharon Springs 

are estimated to have accumulated at a rate of about 

115 and 90 feet per million years, respectively. Timeequivalent rocks at Red Bird accumulated at a rate 

of about 75 feet per million years, whereas those at 

Round Butte in northern Colorado (fig. 23) were deposited at a rate of about 400 feet per million years.

At Red Bird, on the southwestern flank of the Black 

Hills uplift, the average rate of sedimentation for 

the entire Pierre Shale is calculated to have been 

about 340 feet per million years (Gill and Cobban, 

1966b, p. A42), which is considerably more rapid 

than the deposition of the Sharon Springs Member 

in western Kansas.

COMPOSITION

PREVIOUS STUDIES

Investigations of the chemical composition of Cretaceous rocks in western Kansas have been restricted
COMPOSITION 21

K and E Drilling Co. 1 Rand

Center NE^NE^ sec. 11, T. 11 S., R. 42 W.

Wallace County, Kan.

Depth 

(feet)

Spontaneous potential Resistivity

Sohio Petro. 18 State

NWy4NWi/4NEi/4 sec. 34, T. 8 N., R. 5 W.

Logan County, Colo.

Depth 

(feet)

1

General Crude Oil 1 Adams

Center W&NE%NE% sec. 15, T. 12 S., R. 39 W.

Wallace County, Kan.

120 MILES

Northwest Colorado 

Member of Pierre Shale in Kansas, Colorado, Nebraska, and South Dakota.

-20 MILESKansas

largely to the selenium and uranium content of the 

lower part of the Pierre Shale and the Niobrara 

Formation, as well as the soils derived from them. 

Byers (1935, p. 34; 1936, p. 24-50) showed that samples of the Sharon Springs Member of the Pierre 

Shale collected at McAllaster Buttes and elsewhere 

in western Kansas contained 6-23 ppm (parts per 

million) selenium and that vegetation growing on 

these rocks contained as much as 3,700 ppm selenium. Landis (1959, p. 304, pi. 35) showed that the 

organic-rich shale unit of the Sharon Springs contained 10-40 ppm uranium. The Sharon Springs 

Member and its lateral equivalents are abnormally 

radioactive over large areas in the Great Plains.

Radioactivity and uranium content have been reported by Tourtelot (1956) for parts of northeastern 

Colorado, Nebraska, and South Dakota ; by Kepferle 

(1959) for South Dakota and northeastern Nebraska; and by Landis (1959) for eastern Colorado 

and western Kansas. After a study of surface and 

subsurface data, the above workers concluded that, 

on the average, the Sharon Springs Member contains 

between 10 and 15 ppm uranium and has some thin 

beds containing as much as 250 ppm uranium. Landis (p. 304, pi. 35) collected four channel samples 

from the upper 11 feet of the organic-rich shale unit 

of the Sharon Springs at McAllaster Buttes (loc. 

2, this rept.) that contained about 0.004 percent 

uranium.
22 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

* £ ,.;

.ivle-~"*!»,. hu** iifWi" V»

FIGURE 18. Phosphatic shale unit of Sharon Springs Member of Pierre Shale showing buttress-weathering character 

of shale and numerous thin layers of phosphate nodules, 

locality 6. Light bands to left of pick handle are thin nonswelling bentonite beds.

FIGURE 19. Contact of phosphatic shale unit of Sharon 

Springs Member with overlying Weskan Member of Pierre 

Shale, SE% sec. 1, T. 12 S., R. 37 W., Logan County, Kans., 

about 2 miles north of McAllaster Buttes. Contact is at base 

of yellowish-gray laminated tabular limestone concretion.

MINERALOGY

Compositional data from this study are reported 

in tables 1-5. X-ray, six-step spectrographic analyses, and partial chemical analyses in table 1 are 

for samples of cuttings from the Guy Holland test 

hole, and data in table 2 are for samples from outcrops within a few hundred feet of the test hole.

Table 3 gives X-ray analyses for samples of the 

Pierre Shale at other localities, and table 4 gives 

X-ray analyses for bentonite beds from both the test 

hole and the outcrops in western Kansas. Localities 

and stratigraphic relations of most of the samples 

are in the measured sections or at the bottom of 

table 3.

The Guy Holland test hole (loc. 6) started at 

the Weskan-Sharon Springs contact, penetrated approximately 220 feet of Sharon Springs and about 

80 feet of the Niobrara Formation, and bottomed at 

a total depth of 300 feet. Samples of cuttings were 

collected by W. A. Cobban for each 5 feet of drillhole depth, except near the bottom where a 10-foot 

sampling interval was used. Mineralogical analyses 

were only made of every other 5-foot sample from 

the middle depths of the test hole because of the apparent homogeneity of the material. For the mineralogical analyses, particles of bentonite were separated 

from the shale and analyzed separately (table 4).

Mineralogical composition was determined mostly 

by the X-ray diffraction methods described by Schultz 

(1964). Amounts of carbonate minerals were calculated from amounts of mineral carbon, and amounts 

of organic matter (tables 1 and 2) were calculated 

by multiplying the determined organic-carbon values 

by 1.4, a factor derived from unpublished studies of 

organic matter from the Pierre Shale.

FIGURE 20. Phosphate nodule enclosed in gypsum and clay 

rinds, typical of nodules described by Elias (1931, p. 61) 

as concentric concretions, from phosphatic shale unit of 

Sharon Springs Member of Pierre Shale, locality 6.
MINERALOGY 23

NIOBRARA FORMATION

Niobrara samples from the Guy Holland test 

hole contain much more calcite and therefore lesser 

amounts of most other minerals than samples from 

the Sharon Springs, but the amount of pyrite and 

organic matter is about the same. Mixed-layer clay 

in the Niobrara, like that in the calcareous beds at 

the base of the Sharon Springs, contains a large 

proportion of nonexpanding illitelike layers.

FIGURE 21. Phosphate nodules from phosphatic shale unit 

of Sharon Springs Member of Pierre Shale. Natural size. 

A, Weathered phosphate nodule from phosphatic shale. 

B, Sawed surface of phosphate nodule. Outer rind of white 

gypsum and dark clay contains 0.16 percent PgOs, inner 

light-brown bands contain 0.93 percent, and dark-brown 

core contains 2.62 percent.

SHARON SPRINGS MEMBER OF THE PIERRE SHALE

Most samples of shale from the Sharon Springs 

of western Kansas (tables 1-3) contain 50-70 percent clay minerals. The clay-mineral fraction is composed mostly of montmorillonite and mixed-layer 

clay, plus about 20 percent illite, 10 percent kaolinite, 

and, in the fresh test-hole cuttings, a few percent 

chlorite. Montmorillonite and mixed-layer components probably represent a single mixed-layer clay 

with varying proportions of swelling montmorillonitelike layers and nonswelling illitelike layers. The 

low proportion of montmorillonite indicates that 

nonexpandable illitelike layers are abundant in the 

mixed-layer clay, especially in the calcareous samples 

in the lower part of the member (table 1). Lithium 

treatment of the shale samples (discussed in "Bentonites") indicates that most of the expandable layers of 

the mixed-layer clay are beidellitelike rather than 

truly montmorillonitic.

Nonclay minerals from the fresh test-hole cuttings 

of the Sharon Springs consist of quartz, a few percent feldspars, and about 5 percent each of dolomite, 

pyrite, and organic matter. Near its base, where the 

shale grades into the Niobrara Formation, the member contains several percent calcite.

Weathering effects are evident in most outcrop 

samples from the Sharon Springs Member. Each of 

the top two test-hole samples contains only about 

1 percent organic matter and is conspicuously lighter 

in color than samples from below, owing to nearsurface oxidation of organic matter (table 1). The 

top two samples also contain jarosite rather than 

pyrite, which is at greater depths. Nearby outcrop 

samples (table 2) contain jarosite and some gypsum 

but are not conspicuously bleached. The mineralogical data in tables 1 and 2 suggest other effects of 

near-surface weathering. Chlorite is not found above 

a depth of 20 feet, dolomite not above 25 feet, and 

pyrite not above 15 feet in the test hole, and none 

of the three minerals is found in nearby surface samples. In subunits 1 and 3 at locality 6, outcrop samples collected from a deep gully below the layer of 

large concretions (fig. 4) are stratigraphically equivalent to samples that are from beds below the same 

concretion layer in the test hole at a depth of 25-35 

feet and that contain pyrite, chlorite, and dolomite.

Most other outcrop samples from the Sharon 

Springs in western Kansas (table 3) show similar 

effects of weathering. The two Sharon Springs samples that do contain chlorite or dolomite are from 

the light- to medium-gray beds in the dark soft shale 

unit of the member. Sulfuric acid from oxidized 

pyrite apparently leaches fairly soluble dolomite and
24 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

FIGURE 22. Contact of phosphatic shale unit of Sharon Springs Member of Pierre Shale with overlying soft dark shale 

of Weskan Member. Large blocks littering outcrop are float from Ogallala Formation which caps McAllaster Buttes, 

locality 2.

chlorite only from the dark-gray fissile organic-rich 

pyritic Sharon Springs shales. Iron and sulfur reprecipitates as jarosite, limonite, and gypsum. The 

analyzed jarosite from the outcrop sample of stratigraphic subunit 15 near the test hole was a hydrogen 

variety [HFe3 (SO4 ) 2 (OH) 6] rather than the more 

common potassium variety [KFe3 (SO4 )2(OH)6].

UPPER MEMBERS OF THE PIERRE SHALE

The samples from the Weskan, Lake Creek, and 

Salt Grass Members of the Pierre Shale are more 

montmorillonitic than typical Sharon Springs shale 

(table 3). Several contain chlorite and dolomite, and 

thus they seem not so susceptible to weathering, 

probably because the shales are more montmorillonitic and are therefore less permeable to surface 

solutions and because they contain less acid-forming 

pyrite. These differences between the Sharon Springs 

and overlying members of the Pierre in western

Kansas are generally comparable to those observed 

farther north, in Nebraska, South Dakota, Wyoming, 

and Montana (Tourtelot and others, 1960; Schultz, 

1965).

BENTONITES

Bentonites in the Sharon Springs Member and the 

Niobrara Formation of western Kansas differ from 

those in the Weskan Member and from most other 

bentonites in that they contain significant amounts 

of kaolinite and in that the montmorillonite composing the remainder of the clay fraction tends to be 

an aluminum-interlayered beidellitic variety (table 

4). These features, which seem to be most strongly 

developed in the thinner bentonites, are explained 

with reference to the diagram of the montmorillonite 

structure in figure 24.

The montmorillonite layer is composed of a layer 

of alumina octahedrons (an A1+3 ion surrounded by 

four O-2 ions and two (OH)-1 ions) between sheets
MINERALOGY 25

of silica tetrahedrons (a Si+4 ion surrounded by four 

0~2 ions). Each oxygen at the apex of the silica 

tetrahedron is shared with an alumina octahedron. 

As illustrated, the positive charge on the Si+4 and 

A1+3 cations is exactly balanced by the negative 

charge on the 0~2 and (OH)-1 anions. However, 

substitutions of cations of lower charge for the Si+4 

and A1+3 (fig. 24) produce a net negative layer 

charge. In the octahedral layer, Mg+2 replaces A1+ 3 , 

and the resultant mineral is montmorillonite; in the 

tetrahedral layer, A1+3 replaces Si+4, and the resultant mineral is beidellite. The net negative layer 

charge caused by substitutions within the layer must 

be balanced by cations, most commonly Na+1 or 

Ca+2 , in interlayer positions. The thickness of the 

montmorillonite layer (fig. 24) is about 9.6 A (angstroms) , but this thickness applies only at extremely 

low humidity or when the clay is heated to a few 

hundred degrees centigrade. Under normal room 

conditions, water molecules from the air are absorbed between the layers and so the layers swell to 

12-15 A in thickness.

Many Sharon Springs and Niobrara bentonites 

from western Kansas contain montmorillonitic clay 

in which A1+3 , rather than Na+1 or Ca+2 , is the 

principal interlayer cation. The A1+3 forms fairly 

stable Al-hydrate complexes that are not dehydrated 

at 300°C, or even at 550°C in some samples, and the 

basal spacing of the heated sample remains notably 

greater than 9.6 A. Such abnormally high basal spaeings on X-ray diffraction patterns for heated clay 

are the basis for evaluations of the interlayer aluminum complexes reported in table 4.

Beidellite is distinguished from montmorillonite 

(table 4) on the basis of the lithium test of GreeneKelly (1955). In the montmorillonite structure (fig. 

24), all tetrahedral cation positions are occupied, but 

one of every three octahedral A1+3 positions is not. 

When a Li+^saturated sample of the mineral montmorillonite is heated, small Li +1 ions enter vacant 

cation sites in the octahedral layer and neutralize 

the negative layer charge, which causes the clay to 

become nonexpanding and to have a basal spacing of 

about 9.6 A. Beidellite, similarly treated, remains 

expanding because its layer charge is in the tetrahedral layer, which contains no vacant cation sites 

for the Li +1 ions. Effects of the lithium test on bentonites from western Kansas (table 4) show that the 

Weskan bentonites contain octahedrally charged 

montmorillonites and thus are similar to most Pierre 

bentonites. Those from the Sharon Springs Member 

and the Niobrara Formation are exceptionally beidellitic. It should be noted that the name montmorillonite is used both as a group name (tables 1-4) and

as a specific mineral name (table 4).

The relationship between composition and thickness of Sharon Springs bentonites is illustrated by 

the six bentonites from near the Guy Holland test 

hole (table 4). The two thickest (loc. 6, subunits 12, 

14) are the least kaolini.tic, the two thinnest (subunits 8,16) are predominantly kaolinite, and the two 

of intermediate thickness (subunits 6, 10) have intermediate amounts of kaolinite. The three thinnest 

bentonites contain the most interlayer aluminum. 

There is a smaller proportion of montmorillonite 

layers than beidellite layers in the thinner bentonites, 

though this relation is not as consistent as the others. 

Actually, even the thicker bentonites with a montmorillonite-beidellite ratio of 55:45 are still considerably more beidellitic than most Pierre bentonites.

The Sharon Springs and Niobrara bentonites just 

described are exceptionally aluminous owing to kaolinite content, beidellitic character, and interlayer 

aluminum complexes. Kaolinite differs from montmorillonite (fig. 24) in that kaolinite has only one 

silica layer combined with an alumina layer and has 

no cation substitutions, interlayer cations, or absorbed interlayer water. Thus, kaolinite contains 40 

percent A1203 , whereas the mineral montmorillonite 

contains about 20 percent. Beidellite, because A1+3 

replaces Si+4, contains about 25-30 percent A1203 

and little MgO. Interlayer aluminum adds further to 

the A1203 content of these bentonites. An additional 

result of these unusual features is that the content 

of magnesium, calcium, sodium, and potassium is 

unusually small (tables 2 and 4; subunits 12, 14), 

totaling about 2 percent, less than half the normal 

content for the mineral montmorillonite (Grim, 1968, 

p. 578). Even lower amounts of these elements would 

be expected in other bentonites (table 4) in which 

all three of the aluminous characteristics are more 

highly developed than in the two bentonites shown 

in table 2.

The aluminous character of these clays implies 

acidic conditions either at the time of formation or 

during subsequent alteration or weathering. As previously mentioned, recent weathering of the shales 

has oxidized the pyrite, from which the iron and sulfur went into the jarosite, limonite, and gypsum. 

Sulfuric acid solutions have removed dolomite and 

chlorite from near-surface shales. Similar acid solutions could have formed the aluminous clays of the 

bentonites, except that such bentonites are at considerable depth in the test hole (table 4) interbedded 

with pyrite-, dolomite-, and chlorite-bearing shales 

(table 3). Therefore, the type of acidic conditions 

that produced the highly aluminous bentonites remains a problem.

459-596 O - 72 - 4
26 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

TABLE 1. Analyses of sample cuttings from the Sharon Springs Member of the Pierre Shale

[Analyses reported as percentages. Carbon analyses by I. C. Frost. Total carbon determined by induction-furnace analysis, mineral carbon determined by 

gasometric analysis, and organic carbon computed as difference between total and mineral carbons. Six-step spectrographic analyses by J. C. Hamilton, 

reported to the nearest number in the series 1, 0.7, 0.5, 0.3, 0.2, 0.15, 0.1, and so on; values represent approximate midpoints of groups of data on a 

geometric scale. The assigned group for six-step results will include more accurately determined values about 30 percent of the time. Symbols used

Carbon 

analyses Six-step spectrographic analyses

Sample depth 

(ft)

Laboratory 

No.

Al Fe Mg Ca Na Ti Ag Ba Co Cr Ga

PIERRE SHALE, SHARON SPRINGS MEMBER 

Phosphatic shale unit

0-5

5-10

DUO-651

652

0.88

1.03

0.15

.15

0.7

.9

M

M

M 3

5 5

1 21 3 0.3

.571 2 .1

0.015

.07

0

0

0.015

.005

0.05

.05

0.001

.001

0.01

.007

0.01 0.005

.01 .002

Organic-rich shale unit

10-15

15-20

20-25

25-30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

DUO-653

654

655

656

657

658

659

660

661

662

663

664

665

666

4.75

9.81

5.99

8.53

5.69

5.28

5.32

4.53

5.47

5.28

5.88

5.28

5.39

4.98

0.03

.16

.19

5.42

.63

.48

.33

.54

.70

.54

.67

.89

.91

.88

4.7

9.6

5.8

3.1

5.1

4.8

5.0

4.0

4.8

4.7

5.2

4.4

4.5

4.1

M

M

M

M

M

M

M

M

M

M

M

M

M

M

7 7

7 5

M 3

7 2

7 3

7 2

M 5

7 5

M 5

7 5

7 5

7 3

7 3

7 3

0.5 1.5 1.5 2 0.2

.7 1.5 .7 2 .2

1.5 1 .7 2 .2

1 M .5 2 .1

1.5 1.5 .7 2 .3

1.5 1 .7 2 .2

1.5 1 1 3 .3

1.5 1.5 .7 2 .3

1.5 2 1 3 .2

1.5 1.5 .7 3 .2

1.5 1.5 1 3 .2

1.5 2 1 3 .2

1.5 1.5 1 2 .2

1.5 1.5 1 2 .2

0.015

.03

.015

.07

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

0

.00015

.0001

0

0

0

0

0

0

0

0

0

0

0

0.015

.01

.015

.003

.015

.015

.015

.015

.02

.015

.015

.015

.015

.015

0.05

.03

.03

.2

.03

.05

.03

.03

.03

.03

.03

.03

.03

.03

0.001

.002

.0015

.001

.002

.0015

.002

.002

.002

.002

.002

.002

.0015

.0015

0.015

.01

.007

.005

.007

.007

.01

.007

.007

.007

.007

.007

.007

.007

0.02 0.005

.02 .003

.015 .005

.007 .0015

.01 .003

.01 .003

.01 .005

.01 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

Dark soft shale unit

80-85

85-90

90-95

95-100

100-105

105-110

110-115

115-120

120-125

125-130

130-135

135-140

140-145

145-150

150-155

155-160

160-165

165-170

170-175

175-180

180-185

185-190

190-195

195-200

200-205

205-210

210-215

215-220

DUO-667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

4.91

4.85

4.91

5.03

5.17

5.21

5.51

4.88

5.86

5.37

6.10

5.57

5.38

5.07

5.07

4.43

4.81

5.29

5.94

4.15

4.53

4.44

4.74

4.60

4.64

5.13

4.90

6.22

0.89

.80

.84

.89

.87

.97

1.06

.90

.92

.96

1.11

.95

.89

.98

1.28

.85

.98

.88

2.45

.78

.99

1.32

1.48

1.58

1.85

2.23

1.88

2.63

4.0

4.0

4.1

4.1

4.3

4.2

4.4

4.0

4.4

4.4

5.0

4.6

4.5

4.1

3.8

3.6

3.8

4.3

3.5

3.4

3.5

3.1

3.3

3.0

2.8

2.9

3.0

3.6

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

7 3

7 3

7 3

7 3

7 3

7 3

7 3

7 3

7 3

M 5

7 3

M 5

7 3

7 3

7 3

M 3

M 5

M 5

M 3

M 3

M 3

7 3

M 3

M 3

M 3

M 3

M 3

7 3

2 21 3 0.3

1.5 1.5 1 2 .2

2 1.5 1 3 .2

1.5 2 1 2 .2

1.5 2 1 2 .3

1.5 2 1 3 .3

1.5 2 1 2 .2

1.5 2 1 2 .2

1.5 2 1 3 .2

2 31 2 .3

1.5 2 1 2 .2

2 21 2 .3

1.5 2 1 3 .3

1.5 2 1 3 .3

1.5 3 1 2 .2

1.5 1.5 1 2 .3

1.5 2 1 3 .3

2 1.5 1 3 .3

1.5 7 1 2 .2

2 1.5 1 3 .3

1.5 1.5 1 3 .3

1 1.5 1 3 .2

1.5 3 1 3 .3

1.5 3 1 3 .3

1.5 3 1 3 .3

1.5 5 1 3 .2

1.5 5 1 3 .3

1.5 7 1 3 .2

NIOBRARA FORMATION, SMOKY HILL

220-225

225-230

230-235

235-240

240-245

245-250

250-255

255-260

260-265

265-270

270-280

280-290

290-300

DUO-695

696

697

698

699

700

701

3702

703

704

705

706

707

8.57

9.97

10.6

10.8

11.7

11.5

11.1

(3)

7.98

7.67

12.0

12.0

4.62

5.70

6.05

7.38

7.67

8.56

7.93

(3)

4.71

6.04

8.42

8.32

4.0

4.3

4.6

3.4

4.0

2.9

3.2

(3)

3.3

1.6

3.6

3.7

M

M

M

7

7

7

7

7

M

7

3

3

7 3

5 2

3 2

5 2

5 3

5 2

3 2

3 2

7 3

5 1.5

2 3

2 2

1 Ml 3 0.2

1 M .7 3 .07

.7 M .1 2 .07

.7 M .7 2 .05

.5 M .7 2 .07

.3 M .7 2 .05

.5 M .7 2 .05

0.5 M 0.7 2 0.07

1.5 M 1 2 .2

1 Ml 2 .07

.3 M .7 1.5 .05

.3 M .7 1.5 .03

0.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.02

.015

.015

.015

.015

.015

.015

.015

.015

MEMBER

0.015

.01

.01

.015

.015

.01

.01

0.01

.015

.015

.01

.01

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(PART)

0

0

0

0

0

0

0

0

0

0

0

0

0.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.015

.02

.01

.015

.015

.015

.02

.015

.015

.015

.015

.015

0.01

.003

.003

0

0

0

0

0

.007

.003

0

0

0.03

.03

.05

.03

.03

.03

.05

.05

.03

.05

.03

.03

.05

.07

.03

.05

.05

.05

.05

.05

.05

.05

.05

.05

.05

.05

.05

.05

0.03

.05

.02

.02

.02

.02

.05

0.02

.03

.02

.05

.02

0.0015

.001

.0015

.001

.0015

.0015

.001

.001

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

.0015

0.0015

.0015

.0015

.0015

.0015

.0015

.001

0.001

.0015

.001

.0015

.0015

0.007

.01

.007

.007

.01

.007

.007

.007

.007

.01

.007

.01

.01

.007

.007

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.007

0.007

.007

.007

.005

.005

.005

.005

0.005

.007

.005

.005

.005

0.007 0.003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.01 .003

.01 .005

.01 .003

.007 .003

.007 .003

.007 .003

.007 .003

.007 .003

.01 .005

.005 .005

.005 .005

.005 .005

.005 .003

.005 .003

.005 .003

.005 .003

.005 .003

0.005 0.002

.005 .002

.003 .0015

.003 .0015

.003 .001

.002 .001

.002 .001

0.002 0.0015

.003 .002

.003 .0015

.003 .0007

.003 .0007

1 7 percent jarosite. 2 4 percent jarosite. 3 Insufficient sample.

BASALUMINITE AND HYDROBASALUMINITE

Basaluminite (2Al203-S03rlOH20), accompanied 

by a trace of hydrobasaluminite (2Al20.vS03 -41H20), 

occurs as white earthy lumps in association with 

gypsum and limonite in a 0.2-foot-thick zone at the 

top of the Sharon Springs Member near the Guy

Holland test hole (loc. 6, subunit 22). The layer 

resembles the "trash" zones at disconformities in 

the Sharon Springs along the Missouri River in 

South Dakota (Schultz, 1965, p. B6). Basaluminite 

and hydrobasaluminite are rare minerals, first described from England by Hollingsworth and Bannister (1950). In the United States, these minerals have
MINERALOGY 27

and the Smoky Hill Member of the Niobrara Formation from the Guy Holland test hole

are: M, major constituent, greater than 10 percent; 0, looked for but not detected. Elements looked for but not detected: P, As, Au, Be, Bi, Cd, 

Ce, Ge, Hf, In, Li, Pd, Pt, Re, Sb, Sn, Ta, Te, Th, Tl, U, W, Pr, Nd, Sm, Eu. Equivalent uranium analyses, by Wayne Mountjoy, Lorraine Lee, 

and H. H. Lipp, were by beta-gramma sealer. Mineralogical analyses by X-ray diffraction]

Mineralogical analyses

Six-step spectrographic analyses Continued

La Mo Nb Ni Pb Sc Sr V Y Yb Za

E

0

3

Zr J g

W a

PIERRE SHALE, SHARON SPRINGS MEMBER 

Phosphatic shale unit Continued

0.003 

0

0.003 

.003 

0 

0 

.003 

0 

.003 

.003 

0 

0 

.003 

0 

.003 

0

O.Q03 

0 

0 

0 

0 

0 

.003 

0 

0 

0 

.003 

.003 

0 

.003 

0 

0 

0 

.003 

0 

0 

.003 

0 

.003 

.003 

.003 

.003 

.003 

0

0.0005 

.0015

0.003 

.003 

.003 

.002 

.005 

.003 

.005 

.005 

.005 

.005 

.005 

.003 

.002 

.003

0.002 

.002 

.002 

.0015 

.002 

.003 

.0015 

.0015 

.002 

.002 

.003 

.003 

.0015 

.0015 

.002 

.0015 

.002 

.002 

.0015 

.002 

.0015 

.001 

.0015 

.0015 

.001 

.0015 

.002 

.002

0 

0

0 

0 

.001 

0 

0 

0 

0 

0 

.001 

.001 

.001 

0 

0 

0

0 

0 

.001 

.001 

.001 

0 

.001 

.001 

.001 

.001 

.0015 

.0015 

.0015 

0 

.001 

.001 

.001 

.001 

0 

.001 

.002 

.0015 

.0015 

.0015 

.0015 

.0015 

.0015 

.0015

0.003 

.003

0.005 

.01 

.007 

.005 

.007 

.007 

.007 

.007 

.007 

.007 

.007 

.007 

.005 

.007

0.007 

.005 

.007 

.005 

.007 

.007 

.007 

.005 

.007 

.007 

.007 

.007 

.005 

.005 

.005 

.005 

.007 

.007 

.005 

.007 

.005 

.005 

.005 

.005 

.005 

.005 

.005 

.007

0.003 

.002

0.002 

.002 

.003 

.0015 

.003 

.003 

.005 

.003 

.005 

.005 

.005 

.003 

.003 

.003

0.007 

.005 

.005 

.003 

.003 

.005 

.003 

.003 

.005 

.005 

.005 

.005 

.005 

.005 

.003 

.005 

.007 

.005 

.003 

.005 

.005 

.003 

.005 

.003 

.005 

.003 

.003 

.003

0.001 

.0007

0.001 

.001 

.001 

.001 

.0015 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001

0.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.0015 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001 

.001

0.03 

.05

0.05 

.02 

.015 

.07 

.02 

.02 

.02 

.015 

.02 

.02 

.02 

.02 

.02 

.02

0.02 

.02 

.02 

.02 

.02 

.02 

.02 

.02 

.02 

.03 

.03 

.02 

.02 

.02 

.03 

.02 

.03 

.03 

.03 

.03 

.02 

.03 

.03 

.05 

.03 

.05 

.05 

.05

NIOBRARA

0.003 

0 

0 

0 

0 

0 

0

0 

.003 

0 

0 

0

0.002 

.002 

.002 

.002 

.003 

.003 

.0015

0.0015 

.003 

.0015 

.003 

.003

0.0015 

0 

0 

0 

0 

0 

0

0.0015 

0 

0 

0 

0

0.007 

.007 

.007 

.007 

.007 

.007 

.005

0.005 

.007 

.005 

.007 

.007

0.002 

.002 

.0015 

.0015 

.001 

.001 

.0015

0.002 

.003 

.002 

0 

.001

0.001 

.0007 

.0007 

.0007 

.0007 

.0007 

.0007

0.0007 

.001 

.0007 

.0005 

.0005

0.07 

.1 

.1 

.15 

.15 

.2 

.15

0.15 

.1 

.15 

.15

.2

0.03 0.003 0.0003 0 

.02 .002 .0003 0

Organic-rich shale unit

0.03 0.003 0.0003 0 

.03 .003 .0005 .05 

.03 .003 .0003 .03 

.02 .0015 .0002 0 

.03 .003 .0005 .07 

.03 .002 .0003 0 

.03 .003 .0003 .07 

.03 .002 .0003 .05 

.03 .002 .0003 .03 

.03 .002 .0003 0 

.03 .003 .0003 0 

.03 .002 .0003 0 

.02 .002 .0003 0 

.02 .002 .0003 0

Dark soft shale unit -

0.03 0.003 0.0003 0 

.03 .002 .0003 0 

.03 .002 .0003 .03 

.03 .002 .0003 0 

.03 .003 .0003 0 

.03 .003 .0003 .05 

.03 .002 .0003 .03 

.02 .002 .0003 0 

.03 .003 .0005 .03 

.03 .003 .0005 .03 

.03 .002 .0003 .03 

.03 .002 .0003 .05 

.03 .002 .0003 .05 

.03 .003 .0003 .03 

.03 .002 .0003 0 

.03 .002 .0003 .03 

.03 .003 .0003 0 

.03 .003 .0003 0 

.03 .002 .0003 .05 

.03 .002 .0003 .03 

.05 .003 .0003 .03 

.03 .002 .0003 0 

.05 .003 .0005 .05 

.05 .002 .0003 0 

.05 .002 .0003 0 

.05 .002 .0003 0 

.05 .003 .0003 0 

.05 .002 .0003 0

FORMATION, SMOKY HILL

0.05 0.002 0.0003 0 

.05 .002 .0003 0 

.05 .0015 .0003 0 

.05 .002 .0002 0 

.05 .0015 .0003 0 

.05 .0015 .0002 0 

.05 .0015 .0002 0

0.05 0.0015 0.0002 0 

.05 .002 .0003 0 

.03 .0015 .0002 0 

.05 .0015 .0002 0 

.05 .0015 .0002 0

0.01 0.003 

.005 .002

 Continued

0.01 0.003 

.01 .004 

.007 .002 

.003 .001 

.01 .002 

.007 .002 

.01 .003 

.01 .003 

.01 .003 

.01 .002 

.01 .005 

.01 .003 

.01 .002 

.01 .002

- Continued

0.01 0.002 

.01 .002 

.01 .002 

.01 .002 

.01 .002 

.01 .002 

.01 .001 

.007 .003 

.01 .003 

.01 .002 

.01 .002 

.01 .002 

.01 .002 

.01 .003 

.01 .002 

.01 .002 

.01 .001 

.01 .003 

.007 .001 

.01 .002 

.01 .003 

.007 .001 

.01 .002 

.01 .002 

.007 .002 

.007 .003 

.007 .002 

.01 .002

Clay mineral, as 

percentage of total clay

V

o

E

c 

o

s

T3 

K .*; § s

.- °3

J3 tt 

U ^

O 3 H o

Composition of sample, 

in percent

.2 2 .5 

E W u

2 

E v

1 £

E

'3 

I 1

0 H

Continued

18

23

22 

20 

26 

12 

10 

10 

10

11

13

11

16

19 

19

23

18

25

50

23

16

17

9

7

4

0

0

MEMBER (PART) 

0.007 0.002 

.005 .002 

.003 .002 

.003 .001 

.003 .002 

.003 .002 

.003 .001

0.003 0.002 

.007 .002 

.005 .001 

.003 .002 

.003 .001

0

6

5

7

4

7 

7 

0

40 30 

40 26

41 25 

48 19 

41 21 

51 20 

46 24 

52 20 

53 20

48 25

47 24

50 26

42 27

46 23 

45 22 

40 21

47 20

45 17

25 20

42 22

48 19

46 20

48 24

48 27

54 23

58 22

60 21

0 12 

0 11

0 12 

0 13 

6 6 

6 11 

4 16 

3 15 

4 13

4 12

3 13

4 9

3 12

3 9 

3 11 

2 14

3 12

3 10

1 4

2 11

3 14

1 16

3 16

3 15

1 18

3 17

3 16

65 22 

65 24

70 20 

50 15 

55 22 

35 12 

55 24 

55 22 

55 23

50 24

50 25

50 25

50 27

50 28 

50 27 

55 27

55 22

50 25

50 25

55 26

50 27

55 27

45 15

55 20

55 20

55 20

50 23

400 

220

220 

210 

100 

1 1 42 

120 

110 

100

210

100

110

110

200 

210 

320

300

220

300

200

312

100

1 0 17

212

109

1 0 10

218

o a)

0 <2>

0 0 

0 1"6 

0 9 

2 7 

4 9 

4 9 

2 8

5 10

4 10

8 9

8 5

7 7 

8 4 

8 3

8 6

7 7

8 8

6 4

8 6

7 4

4 3

7 4

4 3

5 4

6 6

1 99 

1 98

7 101 

13 97 

8 95 

3 103 

7 102 

7 99 

7 96

7 99

7 97

6 100

6 98

6 100 

6 98 

6 104

6 100

6 99

7 101

6 99

5 102

5 99

5 90

5 96

5 97

4 99

4 100

Continued

56 23

52 20

56 22

41 19

55 22

54 22 

54 18 

54 20

2 19

0 22

1 16

1 32

4 15

1 16 

1 20

1 25

40 15

20 7

20 10

0 4

30 12

15 5 

15 6 

10 3

1 0 29

0 0 50

1 0 55

0 0 65

1 0 40

0 0 60 

1 0 70 

0 0 68

5 5

1 8

0 8

0 7

2 5

0 10 

0 6 

0 11

6 101

7 93

6 100

5 91

.. 90

2 92 

5 103 

5 97

been found in Tennessee (Milton and others, 1955) 

in an altered residuum at the base of the Chattanooga Shale, in southwestern Indiana (Sunderman 

and Beck, 1965) in a weathered residuum at the unconformity between Mississippian and Pennsylvanian 

rocks, and in southeastern Kansas (Tien, 1968) in 

an altered shale above a Pennsylvanian coal. In most

of these the basaluminite or hydrobasaluminite is 

attributed to leaching of silicate minerals at ancient 

or modern land surfaces by acid solutions derived 

from oxidizing pyrite. The presence of these minerals in the Pierre is probably similarly related to 

oxidation of pyrite.
28 THE SHARON SPRINGS MEMBER OP THE PIERRE SHALE IN WESTERN KANSAS

TABLE 2. Analyses of samples from the Sharon Springs and Weskan

[Subunit 24 is in Weskan Member; all others in Sharon Springs Member. All analyses, except atomic-absorption analyses, reported as percentages.

method, reported as parts per billion. Mineralogical

Carbon analyses Six-step spectrographic analyses

Subunit 

sampled

Rock 

type

Laboratory 

No.

Si Al Fe Mg Ca Na Mn Ag Co Ga

24 Shale ..............

21 Carbonaceous

shale ............

....D128-364

363

0.45 <C

1.99 <

1.01 0.4

.01 2.0

M

M

10 2

7 2

1.0 0.07

.5 .2

0.7

.7

5

5

0.3 0.07 0

.3 .003 0

0.01

.01

0.05

.07

0.007

.0003

0.015

.02

0.015 0.003

.02 .003

15

15

14 

12

....do................

....do................

do

....do................

....do................

Bentonite .... 

do

......... 362 6.48

......... 361 10.4

........ 360 6.04

......... 359 6.54

........ 366 .21 

......... 365 .18

<.01 6.5

<.01 10.4

.02 6.0

<.01 6.5

.01 .8

.01 .2 

<.01 .2

M

M

M

M

M

M 

M

7

5

7

7

7

7

M

2

2

1.5

1.5

1.5

1.0 

1.5

.5

.5

.7

.5

.7

1.0 

1.5

.15

.3

.07

.15

.15

.1 

.07

.7

.7

.7

.7

.5

.2 

.05

3

3

5

5

3

.7 

0

.2

.15

.2

.2

.2

.07 

.15

.003

.007

.007

.003

.003

.01 

.015

.0003

.0001

0

0

0

0 

0

.01

.007

.01

.01

.01

.01 

.01

.07

.05

.05

.05

.05

.015 

.007

.0003

.0005

.0005

.0003

.0003

.0003 

.0007

.03

.015

.01

.01

.01

.0005 

.0007

.05

.03

.015

.007

.03

.0015 

.007

.003

.003

.003

.003

.003

.002 

.002

RED BIRD 

FEET WYOMING

Top of Range Zone of Baculites asperiforn

Red Bird data from Gill and Cobban (1966b) 

RED BIRD, WYO., TO SHARON SPRINGS, KANS.

of Range Zone of fec 

Top of Range Zone of Baculites asperiformi

Top of Range Zone of Baculites obtusuf: (late form)

Top of Range Zone of Baculites obtusus (early form)

Niobrara Formation (part)

FIGURE 23. Thickness and implied rates of sedimentation of the Pierre Shale in western Kansas compared with thickness
MINERALOGY

Members of the Pierre Shale from outcrops near the Guy Holland test hole

29

Carbon analyses, six-step spectrographic analyses, and mineralogical analyses, see table 1 headnote. Gold and silver contents, determined by atomic-absorption 

analyses by J. A. Thomas and J. D. Mensik, Tr., trace]

AtomicSix-step spectrographic analyses Continued absorption

La Mo Nb Ni Pb

0.003 0.0007 0 0.002 0.003

.007 .0007 0 .0007 .003

.003 .0015 0 .0007 .002

0 .0015 0 .003 .0015

0 .002 0 .002 .002

0 .003 0 .0015 .0015

0 .001 0 .0015 .0015

000 .0015 .001

0 .0005 0 .005 .001

SOUTH DAK

Red Bird.

>.

\1 ___ __ «- . 

WYOMING \

\

\ NEBRAS1

VRound ButteV

\. \

Boulder. N. \

\\Nx \,

COLORADO ^"^4,Sha

^___^ - ^^-~--~~~~~^

Pueblo

1

analyses

Sc Sr V Y Yb Zn Zr Au Ag

0.0015 0.03 0.05 0.0015 0.0003 0 0.01 <0.02 0.4

.0015 .03 .07 .005 .0005 0 .015 <.02 .3

.0015 .015 .03 .007 .0007 0 .015 <.02 1.8

.0007 .007 .03 .001 .0003 0 .007 <-02 1.1

.0007 .005 .05 .001 .0002 0 .007 <.02 .8

.0007 .007 .07 .001 .0002 0 .007 <.02 .6

.0015 .007 .05 .0015 .0003 0 .007 <.02 .5

0 .0015 .015 .001 .00015 0 .005 <-02 .3

.0005 .001 .015 .0015 .0002 0 .007 <-02 .4

.OTA r

a

 N i ^i ijr

I t

s:

tCA

~

600ft ""- ...^^^^^

Mineralogical analyses

Clay mineral, as

percentage of total clay

'3

~ > frs

° « S % -3 & "° - c -S 

c ^ 4_> £ 'o S

1 i s 5 Z &

11 59 17 0 13 70

13 64 15 0 8 65

32 34 20 0 14 60

14 50 24 0 12 50

21 46 20 0 13 60

13 53 20 0 14 65

15 57 15 0 13 65

95 0 00 5 95

95 0 00 5 95

Composition of sample,

in percent

^~* a>

M *££

1 « ^ £

« -| 1 » 1 1

o- S ui o 3, o

20 12121

23 11043

18 03019

18 1 1 3 10 13

25 01228

28 01119

27 21011

1 0 3 0 Tr. 0

Tr. 00010

_

eg

O

H

97

97

91

96

98

105

97

99

96

T°P of Range ZonT!f°Lf!?.^s Per***,..

1400ft

a.

ron Springs £

.»

KANSAS

ROUND BUTTE

~^~ rop

^Ulltes axperif'^

Niobrara Formation (part)

""" --_

225 ft

, COLO., TO SHARON SPRINGS, KANS.

of Range Zons n, D_ .

 Top of Ranee ? » nf "'D^ C,U.'ttes **rPle*uK __ _

1060 ft

-.., , ^wulltes aspertforrm

s -- -~^______-_____^

-J

225 ft

Niobrara Formation (part)

Boulder data from Scott and Cobban (1965)

BOULDER, COLO., TO SHARON SPRINGS, KANS.

Top of Range Zone of Baculites perplexu 

Top of Range Zone of Baculites asperiformi.

Pueblo data from Scott (1964) 

PUEBLO, COLO., TO SHARON SPRINGS, KANS.

Top of Range Zone of Baculites asperiformi

f Ranee Zone of Bacuhtts obtusus (late for

Top of Range Zone of Baculites obtusus (early form)

Niobrara Formation (part)

and rates in other localities. Each ammonite zone represents approximately 500,000 years (Gill and Cobban, 1966b).
30 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

TABLE 3. Mineralogy of samples from the Pierre Shale

[Tr., trace; ?, presence doubtful]

Clay mineral, as

percentage of

total clay

Composition of sample, 

in percent

Locality Member -2 fc

12* 

II2

143 

14 13* 

2 

6

3 

1 

1 

2 

2 

2 

14

1 

1

4 

5 

1 

35 

17

3 

37 

35 

8 

6 

3 

2

Salt 

Grass...... 

Lake 

Creek..... 

Weskan...... 

....do.............

 do.. 

....do............

Sharon 

Springs., 

 do 

....do.............

....do.............

 do 

.... do. 

.... do. 

 do 

Montmoi

35

28 

41 

31 

37 

36

8 

15 

20 

15 

0 

16 

17 

8

J5

T3 

01

X

i

41

52 

25 

36 

40 

41

52 

53 

41 

45 

69 

52 

53 

53

01

17

13 

31 

20 

18 

17

20 

17 

22 

14 

19 

19 

15 

21

Chlorite

0

1 

2 

4 

0 

2

0 

3 

0 

3 

0 

0 

0 

0

Kaolinife

7

7 

1 

9 

5 

4

20 

12 

17 

23 

12 

13 

15 

18

"o 

"cs 

1

70

60

75 

65 

80 

75

30 

55 

70 

60 

60 

65 

50 

75

Quartz

Plagioch K-feldsp

19 3 0

19 2 0 

25 2 0 

27 Tr. 0 

19 2 0 

18 2 ?

10 0 50 

27 1 1 

28 0 1 

20 1 0 

21 0 1 

20 1 Tr. 

20 1 1 

28 1 1

Dolomite 

Gypsum Jarosite

000

300 

020 

900 

000 

000

000 

OTr. 0 

000 

2 OTr. 

020 

055 

0 10 7 

0 ? 0

"c3

O

H

92

84 

104 

101 

101 

95

90 

84 

99 

85 

84 

96 

89 

105

sec. 19, T. 12 S., R. 40 W., Wallace County. 

2SE% sec. 29, T. 11 S. ( R. 39 W., Wallace County. 

3W% sec. 7, T. 14 S., R. 38 W., Wallace County. 

*SW% sec. 31, T. 12 S., R. 38 W., Wallace County.

POTASSIUM FELDSPAR

It seems unlikely that the large amount of potassium feldspar in the thin light-colored shale subunit 

(table 3, loc. 6, subunit 17) in the lower part of the

Na+ and Ca+2

SiO4 TETRAHEDRONS 

(Al+3 for Si+4 substitutions 

in beidellite)

A1O4 (OH) 2 OCTAHEDRONS 

(Mg +2 for Al+3 substitutions 

in montmorillonite)

SiO4 TETRAHEDRONS

Na+ and Ca+2

FIGURE 24. Structure of a montmorillonite layer (Bragg, 

1937, p. 206). Open circle is oxygen, O"2 ; circled "H" is 

hydroxyl, (OH)-*. Certain O~2 and (OH)~i that otherwise would be superimposed have been slightly displaced. 

Common cation substitutions within the layer are shown 

in parentheses.

phosphatic unit of the Sharon Springs Member, is a 

normal detrital accumulation. Instead it appears to 

be adularia, a pseudomonoclinic potassium feldspar 

of diagenetic origin.

BARITE AND APATITE

Other minerals in the Pierre samples which affect 

the chemical data given in tables 1 and 2 are barite, 

apatite, and possibly gypsum. The barite is in fillings

TABLE 4. Mineralogy of bentonites

[All analyses by X-ray diffraction. A, abundant; Nd., not determined; 0, none; Tr., trace; S, some; Na., not applicable]

Clay mineral, as percentage of total clay Nanclay mineral, 

as percentage of sample 

>.

3

-a

a

A

VI

o S

8-wc °

O 4->

2 % H-d

£ c *. n a Proportion of layers

h .2 >. D *

01 

01

<H

0» 4J C3 

 ° | t

s! 1

c

Bj3"3

JJ)

0

in montmorillonite1

after lithium

Nonexpanded 

montmorillonite2

test

Expanded 

beidellite Mineral Percent

SURFACE SAMPLES 

Near Guy Holland test hole (fig. 15)

Thickness

6 

6

6 

6

6 

6

16 

14

12 

10

8 

6

0.05 Sharon Springs. .. A 

.4 An n

.25

.15

.05

.1

 .do............

...... ....do............

....... ...do............

. ..do............

........ O

........ O

....... A

........ A

Nd. 

55

55 

30

40 

50

Nd. 

45

45 

70

60 

50

85 

5

5 

13

55 

50

8 

1

Tr. 

Tr.

Tr. 

Tr.

K-feldspar 

.... do 

Jarosite 

 do 

K-feldspar 

Jarosite 

K-feldspar 

Jarosite 

K-feldspar 

Jarosite

2 

3 

Tr 

1 

Tr 

Tr 

Tr 

Tr 

Tr 

7

SURFACE SAMPLES 

Other localities

14

13

?,

?,

14 

4

4

3

2

32

34

1 

1

7

Weskan..................

......do.......................

 ..do..... .................

.. do...... ................

Sharon Springs....

 do....................

.... O

... O

.... S

.... O

... A

.... A

.... S

90

95

85

100

25 

50

Nd.

10

5

15

0

75 

50

Nd.

3

0

0

0

45 

45

30

0

0

0

0

3 

3

0

K-feldspar

2

2

SAMPLE CUTTINGS 

Guy Holland test hole

Depth

20-25 

50-55

135-140

155-160

200-205

220-225

Sharon Spring 

............do...........

...... ..do...........

............do...........

 do.. 

Niobrara... ........

s A 

......... A

......... S

......... O

......... Na.

.......... Nd.

50

Nd.

50

25

0

Nd.

50 

Nd.

50

75

0

Nd.

10 

90

15

10

100

75

0 

0

2

0

0

0

Pyrite

....do ...

....do 

.... do .... ....

3

10

15

80

Montmorillonite as a group. 2Montmorillonite as a specific mineral.
CHEMICAL COMPOSITION 31

of septaria in limestone concretions, fragments of 

which are in cuttings from the 25- to 30-foot sample 

depth. Concretionary calcite material is also evident 

from the high calcium and mineral carbon contents 

in cuttings from the 170- to 175-foot interval. The 

high calcium determined for the 5- to 10-foot cuttings cannot represent a calcite source because of 

the small amount of mineral carbon reported; most 

likely, the calcium is from gypsum and apatite in 

phosphate nodules which are abundant in this unit.

CHEMICAL COMPOSITION

Cuttings from the Guy Holland test hole (table 1) 

and samples from nearby outcrops (table 2) were 

analyzed by the Denver laboratory of the U.S. Geological Survey for selected elements by the six-step 

spectrographic method. The approximate lower limits for visual detection of elements are shown in 

table 5. Total and mineral carbon were also determined ; organic carbon is the difference between total 

and mineral carbon. Equivalent uranium was determined only for the test-hole samples.

TABLE 5. Approximate lower limits for visual detection of

elements

[Determined by the six-step spectrographic method at the Denver, Colo., 

laboratory, U.S. Geological Survey]

Element Percent Element Percent Element Percent

Si ......

Al ......

Fe .......

Mg .....

Ca ......

Na ......

K ........

Ti ......

P ........

Mn .....

Ag ......

As ......

Au ......

B ........

Ba ......

Be ......

Bi ......

Cd ......

Ce ......

Co ......

Cr ......

Cs ......

Cu ......

........0.002

........ .001

........ .001

....... .005

........ .005

........ .05

........ .7

........ .0002

........ .5

........ .0001

........ .0001

........ .2

........ .002

........ .002

........ .0002

........ .0001

........ .001

........ .005

........ .015

........ .0003

........ .0001

........2

........ .0001

Dy ......

Er ......

Eu ......

Ga ......

Gd ......

Ge ......

Hf ......

Hg ......

Ho ......

In ......

Ir ......

La ......

Li ......

Lu ......

Mo ......

Nb ......

Nd ....

Ni ......

Os ......

Pb ......

Pd ......

Pr ......

Pt ......

........0.005

........ .005

........ .01

....... .0005

........ .005

........ .001

........ .01

........1

....... .002

........ .001

........ .005

........ .003

........ .01

........ .003

........ .0003

........ .001

........ .007

........ .0003

........ .005

........ .001

........ .0002

........ .01

........ .005

Rb .....

Re .....

Rh .....

Ru ......

Sb ......

Sc .....

Sn ......

Sr .....

Sm ...

Ta ......

Tb .....

Te .....

Th ......

Tl .....

Tm ...

U ........

V .......

W .....

Y .......

Yb .....

Zn .....

Zr .....

......10

...... .005

....... .0002

...... .001

...... .02

...... .0005

...... .001

....... .0005

....... .01

....... .02

....... .03

....... .2

...... .02

....... .005

....... .002

....... .05

....... .0007

....... .01

....... .001

....... .0001

......... .02

......... .001

Summaries of compositional features of the spectrographically analyzed samples in figure 25 and 

tables 6 and 7 are the basis for comparisons in subsequent parts of this report. Figure 25 illustrates 

the common range of composition for sample cuttings from the Sharon Springs Member and the Niobrara Formation and for samples of other groups of 

shales.

Geometric means of concentrations of chemical 

elements and of minerals are listed at the left side 

of table 6. Amounts of elements and minerals in the

Niobrara are recalculated to a calcite-free figure to 

provide a better basis for comparison with the Sharon 

Springs samples, because, judged from the low content of most trace elements in Niobrara samples (fig. 

25), the calcite they contain must contain few trace 

elements and, thus, it acts only to dilute the trace 

elements in the other minerals.

Occurrence of most elements detected in the Sharon 

Springs and Niobrara samples from western Kansas, 

as inferred from factors discussed in the following 

section, is listed on the right side of table 6. Under 

"Inferred occurrence," the percentages given are 

those estimated for each element in each mineral. For 

example, the clay minerals in these samples contain 

an estimated average of 2 percent Fe and make up 

52 percent of an average unweathered noncalcareous 

sample of Sharon Springs shale, and so about 1 percent Fe is in the clay; pyrite contains 46 percent 

Fe, and so the 7 percent pyrite in an average unweathered noncalcareous sample contains 3.2 percent 

Fe. The 4.2-percent sum for iron in clay and pyrite 

is higher than the calculated 3.5 percent mean value 

under "Mean content," but the occurrence figures 

should be regarded only as gross estimates.

Correlation coefficients (table 7) also have been 

calculated between most of the elements and between 

elements and the major mineral components that 

most likely contain them. A strong positive correlation indicates that the two elements or the mineral 

and element tend to occur together, possibly in the 

same mineral, as is obvious for the +0.9 correlation 

between calcium and calcite. However, a positive 

correlation does not necessarily mean that the two 

occur in the same mineral. Possibly they occur in different minerals that are favored by similar geologic 

conditions; pyrite and organic matter, both of which 

require reducing conditions, are good examples. A 

strong negative correlation normally indicates that 

the two elements occur in different minerals; probably little or no titanium or zirconium occurs in calcite. Silicon and aluminum are not included in table 7 

because they occur in amounts for which the ranges 

of the spectrographic groups are so large that they 

are not useful for the correlation statistics. At the 

other end of the scale, silver and lanthanum were 

detected in too few samples to be useful and thus 

are not shown in table 7. Coefficients less than 0.32 

are not shown in table 7 because, if a log-normal distribution of values is assumed, they are not significant at the 99-percent level. Significant coefficients 

are rounded to the nearest single number and the 

decimal is dropped. In table 7, the order of constituents has been arranged to group constituents with 

similar correlation coefficients.
32 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

PERCENT

>10

7

5

3

2

1.5

1

0.7

0.5

0.3

0.2

0.15

0.1

0.07

0.05

0.03

0.02

0.015

0.01

0.007

0.005

0.003

0.002

0.0015

0.001

0.0007

0.0005

0.0003

0.0002

0.00015

0.0001

Not 

detected

Si

+ +'+ +

:::<

++

111

Al

;;;;;<

4 

+ 4 +

4+4

4- 4

Fe

''' $

+ + + +

+ + 

4 + 

+ 4 H>

111

111

| 1

Mg

:'::<

+

 <

+ 44

+'+

444

44 4

ill i

Ca

+ + + + + +

 : : <

' ' <

Na

+ ::::: 

+ :::::<

44 4

1 1 1

;! i 1

K

4- 4

+ ~L+ + + :i:+<

ills

p||gS:

Ti

<

!::!H

+ . +

4- 

4-4-4- 

4-

4- +

+

Mn

<

 <

+ + 

+ + +

4-4-4- 

4- +

B

;<

+

+ + +

III!

Illl

+ * +

+. 4

Ag

S

\

\ 

\ 

\

\

\ 

\

\ 

\

\

\

N

All^ 

the

Ba

_i :-=:=d

a^^+ +4- 

+ +'+ +

Co

^

; " '< '$&

4

+.:: s 

+ \

\ 

\

\

Cr

V

s

'::: >

+ . .

liil^j

:&

\ \

\,

\ 

\ 

\

\ 

\

Cu

=!!!!=;

+ '<

TTl + x 

+ + +\

+ + +x

Ga

: \ 

::: \ 

: \

+ + +<

t^

44 +

4 -tLa

; ;;; :^

4 4

i'li

:|1|

All 

the 

rest

Mo

\

\

S

s

\

\

\

. \ 

' : ' s

+ \ \

+ ':' ^

+ ' X

+.+\ 

^'+ \

+ . N 

+ --;--\ 

+ ' \

\

\

f:||S;J

;: ;K;;r::;:

i'-Hl

Nb

+: +

.:::.<

Ill

f .:. + ::: +

+ + +

Ni

\

\

\

\

\

+.*?+ 

+ +; '+

+ ... +; ;;:;>

Pb

\ \

\ 

\

\

\

\ \

; \ 

 \

\

. . \

 :-\ 

' ' \

\ 

.:: VN::N

+ + j 

+ +-4

:

4

4' 

4

4

Sc

\

 <

4:1:4

+ 4 

4 4 

4 4 

4 4

i

Sr

4

+ 

+

4 4 

4 4 

+ +

+

+

. . \

B

H\ 

* \

\ 

\

V

\

\ 

\ 

\

\

;:-;_.:>;.::_:_:.':..

V

\ 

\

\ \

\

\

\

\

+ +:+\ 

+ ' : +\

+ .:. ^

^

\

\

Y

+:i : +v

+ ; +

<- + + + 

f + + +

Yb

4..... :i!i!^ 4 ^

444 

4444

Zn

\

V

\ 

\

\

HP

ill

+ .:::.+

+ +'+ +

Zr

-i

iiiiii4 4

+ 4

+ 4 + 

+ + 4 +

+

eU

+ + + -t- + .:::.+

+ '" +

+ + 

+ +

<

Niobrara Sharon Springs 

Samples from Guy Holland test hole

Average for Pierre Shale

Ag, La, Nb, Y, and Yb/rom Tourtelot (1962);

other elements from Tourtelot and others (1960)

EXPLANATION

Common range for ordinary shale 

From Krauskopf (1955)

Average for shale 

From Turekian and Wedepohl (1961)

Below detection limit

NOTE. No surface or nodule-bearing 

samples are included

FIGURE 25. Distribution of elements in sample cuttings from the Guy Holland test hole compared with that in other

shales. Data for Niobrara and Sharon Springs samples from table 1.
TABLE 6. Mean content and inferred occurrence, in percent, of chemical elements and minerals in samples from the Pierre Shal

[...., no appreciable amount; Na., not applicable ; ?, doubtful; Nd., not determined]

_________________Mean content 

Guy Holland test-hole samples

Infer

Elements and 

minerals

(from data in table 1)

Pierre Shale, Sharon Springs Member

Weathered,

depth 

0-25 feet

Unweathered 

noncalcareous,

depth 

25-190 feet

Unweathered 

calcareous,

depth 

190-220 feet

Niobrara Formation

Marls tone,

Marlstone calcite 

free

Outcrop samples

(from data on table 2)

Pierre Shale, Sharon

Springs Member

Pierre Shale a

Shale Bentonite

Clay minerals and 

associated 

elastics

Pyrite

Fe............................................ 4.2 3.5 3.0

Mg........................................... .9 1.6 1.4

Ca............................................ 1.5 1.8 3.6

Na........................................... .9 .9 1.0

K............................................. 2.2 2.4 3.0

Ti............................................ .22 .25 .25

Mn.......................................... .018 .020 .015

B.............................................. .014 .015 .016

Ba........................................... .039 .037 .050

Co............................................ .0013 .0015 .0015

Cr............................................ .010 .008 .009

Cu............................................ .016 .008 .005

Ga............................................ .004 .003 .003

Mo........................................... .002 .002 .0014

Nb........................................... .0008 .0009 .0015

Ni................................... . ...... .006 .006 .005

Pb......... . . . .003 .004 .004

Sc......................................... .001 .001 .001

Sr.......................................... .02 .02 .04

V........... ........ ........ ... .03 .03 .05

Y............. ....................... .. .. .003 .002 .002

Yb......... . .................. ..... .0003 .0003 .0003

Zn........................................... .02 .03 .02

Zr............................................ .009 .010 .008

Equivalent uranium........... .003 .002 .002

Organic carbon.................... 5.2 4.3 3.1

Calcite.................................... 0 .1 10

Dolomite................................ 065

Pyrite..................................... 674

Total clay.............................. 60_________52_________55

1Mostly below visual-detection limits. See text and table 5.

2.2 

.6 

20 

.8

2.0 

.07 

.012 

.0024 

.027 

.0014 

.006 

.003 

.0013 

.002 

.0008 

.006 

.0014 

.0007 

.13 

.05 

.002 

.0002 

CD

.004 

.002

3.5 

55

1

7 

20

5.1

1.4

Na.

1.7

4.7 

.16 

.027 

.006 

.062 

.0031 

.013 

.007 

.003 

.005 

<i)

.015 

.003 

.0016 

.3 

.11 

.004 

.0005 

(i)

.009 

.004

8.4

Na.

2

18 

42

1.7 

.6 

.2 

.7

3.9 

.20 

.004 

.009 

.056 

.0004 

.014 

.021 

.003 

.0015 

(i)

.0014 

.002 

.001 

.001 

.05 

.002 

.0003 

ii)

.009 

Nd.

5.4

0

0

0 

61

1.2

1.2 

.8 

.1 

.6 

.10 

.012 

.010 

.010 

.0005 

.0006 

.004 

.002 

.0003 

(i)

.001 

.001 

.0004 

.001 

.015 

.001 

.0002 

(i)

.006 

Nd. 

.02

0

0

0 

95

2 

1.5

1

2

5

.05 

.03 

.03 

.05 

.002 

.015 

.015 

.006 

.001 

.002? 

.005 

.008 

.002 

.04 

.05 

.004 

.0005 

 >

.02 

.002

46

? 

.01
34 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

on the basis of several factors: (1) the common 

modes of occurrence in other rocks, such as have 

been summarized for sedimentary rocks by Tourtelot 

(1962, p. 46), (2*) concentration of elements in individual samples with unique composition, such as the 

top two test-hole samples which contain little organic 

matter and no pyrite or the outcrop samples which 

contain variable amounts of organic matter but no 

pyrite, (3) concentration of an element in the calciterich Niobrara samples and the relative concentration 

when the element is recalculated calcite free, and 

(4) correlation coefficients. The few elements which 

are most abundant in the Niobrara probably are in

TABLE 7. Correlation coefficients, xlO*1 , between elements and minerals in sample cuttings 

from the Guy Holland test hole and nearby outcrops

[Coefficients less than 0.32 not shown]

In tables 6 and 7, elements reported as undetected 

in a sample were assigned values just below the limit 

of detection. This procedure probably is reasonable 

for elements like boron or lead which are below 

detection limits in only a few samples (fig. 25). However, for elements like niobium and zinc for which 

more than half the values were below the limit of 

detection, the mean values (table 6) are probably 

too high.

MODE OF OCCURRENCE OF ELEMENTS

The amount of each element in each mineral and 

in the organic constituent of the samples is deduced

9

9

9

9

8

9

7

7

7

7

6

8

7

6

5

4

4

4

4

-4

-8

-8

-9

tf

9

8

8

8

8

7

7 '

7

7

6

a

7

7

5

3

4

4

-4

-9

-8

-9

\

9

9

8

9

7

7

7

7

6

8

7

6

5

3

4

4

3

-5

-9

-9

-9

' '&*

9

8

8

7

6

8

7

5

7

5

6

5

4

4

4

-4

-8

-8

-9

V

7

8

8

6

7

8

6

6

4

6

5

4

5

4

-4

-5

-8

-8

-9

<°

7

6

6

6

5

4

9

7

6

6

4

3

-3

-4

-8

-7

-8

'* 

6

6

6

6

5

8

6

4

4

4

3

4

-4

-8

-7

-8

^

7

6

6

5

6

3

4

4

5

4

 6

-6

_ 7

/

6

6

5

5

4

3

3

4

5

4

-6

-6

-7

6

6

5

3

6

4

4

3

3

-4

-5

-6

_ 7

6

5

3

6

4

5

5

-7

-8

0

O

-8

4

4

5

3

3

3

-3

-5

-6

-6

7

4

5

3

3

3

-4

-8

-7

-8

' v^P

/

5

3

4

-4

-7

-6

-7

 ^

4

4

-5

-4

-5

-6

/

3

3

-3

 3

-4

V

4

-7

-5

-3

-5

^

/

-4

-4

-4

/

4

4

-4

-4

-5

/

G°

6 ^/ X

6 7 ^x ^

4576 o<e> . Ke / ^S

5766 &

A

-4 6 $

-4 6 9 &* ^ 

[ *£

699 &
MODE OF OCCURRENCE OF ELEMENTS 35

the calcite. When several other elements are recalculated calcite free, their means are notably higher in 

the Niobrara than in the noncalcareous Sharon 

Springs. This could mean either that the element is 

partly in calcite or that it is in pyrite or in organic 

matter, both of which are shown to be about as 

abundant in the Niobrara before the recalculation 

as they are in the Sharon Springs. If, for example, 

an element is only in organic matter, its mean concentration in the recalculated Niobrara would be 

twice that in the noncalcareous Sharon Springs because the Niobrara samples average about half calcite. Only large differences of a factor of about 2 are 

considered significant in comparing the calcite-free 

values.

The presence and amount of major elements obviously are determined by the mineralogy of the 

samples. Silicon is mainly in quartz and clay. Aluminum, potassium, and sodium are mostly in the clay 

minerals; only minor amounts are in feldspars. The 

exceptionally large amounts of potassium in the calcareous Sharon Springs and in the Niobrara that 

have been recalculated calcite free are due, in part at 

least, to the very illitic character of the mixed-layer 

clay in these samples (table 1). About three-fourths 

of the iron must be in pyrite and only about onefourth in clay; some of the iron from the leached 

pyrite is retained in the weathered samples in jarosite. More than half the magnesium and calcium in 

the fresh Sharon Springs sample cuttings must be 

in dolomite, the remainder in clay. Though dolomite 

probably is not a clastic mineral, its abundance generally seems to parallel the abundance of clay, so 

dolomite and clay have similar correlation coefficients.

Four elements titanium, boron, gallium, and 

zirconium have very strong positive correlations 

with the total amount of clay (table 7) and are 

thought to occur almost exclusively in it or with 

other clastic grains that are associated with it (Tourtelot, 1962, p. 46). Gallium replaces aluminum in the 

clay structures, and boron is strongly absorbed on 

clays. Part of or all the titanium and zirconium can 

occur in the clay structures; titanium can also occur 

in separate titanium minerals such as ilmenite or 

anatase (Frederickson, 1948), and zirconium, in 

zircon. If these separate titanium and zirconium 

minerals occur, their abundance must so closely 

parallel the abundance of clay in these fine-grained 

rocks that titanium, zircon, boron, and gallium, as 

well as clay itself, can be equated with the "Clay 

minerals and associated elastics" boxhead in table 6. 

The strong positive correlation coefficients of these 

clay-associated elements with all the other elements 

listed in table 7 between clay and dolomite indicate

that all are mainly in clay or in other clastic components of the sediment.

Lead probably replaces large K+ ions, comparable 

in size to lead, in the interlayer positions of the illitic 

and mixed-layer clays. Scandium can also occur in 

interlayer positions of the clay but, because of its 

small size (0.81 A), is more likely to be in the structure of the clay minerals. The strong negative correlation between scandium and calcium (table 7) 

indicates that scandium does not substitute for calcium in calcite.

Yttrium and ytterbium normally tend to be concentrated with rare earths in monazite and other 

phosphate minerals, which accounts for the exceptionally high yttrium and ytterbium values and the 

highest reported lanthanum value in surface samples 

from subimits 15 (upper) and 21 of the apatite-rich 

carbonaceous shale (table 2). In most samples, however, these elements are in clays or associated heavy 

elastics that contain rare earths. Rankama and Sahama (1950, p. 528) reported that yttrium may replace calcium in calcite. If this substitution accounts 

for the slightly high yttrium mean for the recalculated Niobrara, the substitution is slight.

Chromium and copper contents are fairly uniform, 

showing little or no evidence of variation in those 

samples that contain small amounts of pyrite or 

organic matter. Their contents in the recalculated 

Niobrara are not notably high. If anything, the 

elements are concentrated in the near-surface pyritefree samples. They show their highest positive 

correlations with clay and the four clay-associated 

elements, and are most likely substituting in the 

octahedral sheets of the layers in the clay.

Manganese shows all its positive correlations with 

clay and clay-associated elements, but yet the weakness of all its correlation factors indicates that 

manganese is also disseminated in small amounts in 

other components that are not easy to identify from 

the data. The slightly high mean value of manganese 

for the calcite-free Niobrara samples suggests that 

there is some manganese in calcite, where it commonly replaces calcium (Tourtelot, 1962, p. 46). 

However, the strong negative correlations of manganese with calcium and with strontium and vanadium which also are closely associated with calcite 

indicate that the amount is very small, except perhaps in the calcite from concretions (25- to 30-foot 

sample depth, table 1). The very small amounts of 

manganese in the outcrop samples suggest that some 

manganese has been leached from surface samples.

Barium occurs uniformly in most Sharon Springs 

samples, regardless of the presence of pyrite or organic matter; it occurs in slightly smaller amounts
36 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

in the Niobrara marls. Thus, it must be in the one 

component common to all the samples the clays 

where it replaces potassium. Its exceptionally weak 

correlation coefficients indicate that it also occurs in 

other components. In sample cuttings from the 25- 

to 30-foot depth, it is in barite and may also be in 

other samples in smaller undetected amounts. The 

large amount of barium in the recalculated Niobrara 

suggests that small amounts of barium occur in calcite, although the barium ion is generally too large 

to replace calcium in calcite.

Equivalent uranium shows very weak correlation 

coefficients. Its strongest correlations are with clayassociated elements. The usual strong concentration 

of uranium in organic material in many rocks (Tourtelot, 1962, p. 46) is barely suggested by the weak 

positive correlation with organic carbon in the Guy 

Holland samples. The sample from the 15- to 20-foot 

depth with the highest measured organic-carbon content also has the highest reported equivalent uranium. The weak correlations of equivalent uranium 

probably indicate that it is not a very reliable measure of elemental uranium except in very large 

amounts.

Cobalt and nickel both seem to occur about half, 

or a little more, in the clays and half in pyrite. Concentrations in the three pyrite-free sample cuttings 

from the top of the test hole are one-half to twothirds the Sharon Springs average, and sample cuttings from the pyrite-rich 15- to 20-foot depth 

contain a maximum reported amount of both nickel 

and cobalt. The mean amounts in recalculated Niobrara are more than double the Sharon Springs 

average. The strong positive correlations with both 

organic matter and pyrite would normally indicate 

that nickel and cobalt occ-ur in both. The moderate 

abundance of nickel in the sample cutting from the 

10- to 15-foot depth (table 1) which contains 7 percent organic matter but no pyrite also indicates 

nickel in organic matter. However, the very small 

amounts of nickel and cobalt in the organic-rich but 

pyrite-free outcrop samples (table 2) indicate that 

these elements actually are mostly in pyrite and that 

their strong positive correlations with organic matter are attributable to the fact that abundance of 

organic matter and that of pyrite commonly is parallel in the subsurface samples.

Molybdenum shows its strongest positive correlations with pyrite and organic matter and with the 

elements nickel and cobalt, both of which occur in 

pyrite. Like nickel and cobalt, molybdenum is more 

than twice as abundant in the calcite-free Niobrara 

as in the Sharon Springs. Yet, unlike nickel and 

cobalt, the amount of molybdenum in the pyrite-free

surface samples is only slightly lower than in fresh 

Sharon Springs samples, a fact which indicates that 

molybdenum is concentrated more in the organic 

matter than in the pyrite. The distribution of molybdenum parallels fairly well the highly variable abundance of organic matter in the surface samples. Also, 

molybdenum is commonly interpreted to be concentrated in organic matter (Tourtelot, 1962, p. 46). 

The small amounts of molybdenum in samples nearly 

devoid of pyrite or organic matter must occur in clay.

Strontium shows very strong positive correlations 

with calcium and calcite. All other correlation coefficients except those with vanadium either are 

negative or are not significant. The association of 

strontium with calcite in the Niobrara samples seems 

obvious and, in general, it is a common one (Tourtelot, 1962, p. 46). However, the association may not 

be due to the substitution of strontium for calcium 

in calcite, but rather to the mixing of small amounts 

of strontianite (SrC03 ) with the calcite (Rankama 

and Sahama, 1950, p. 481). Small amounts also must 

occur in clays in interlayer positions to account for 

the strontium in calcite-free samples.

Vanadium correlation coefficients of -f-0.6 with 

calcite, calcium, and strontium are surprising. The 

coefficients, together with the large amounts of vanadium in Niobrara samples (table 6), indicate that 

vanadium occurs in calcite. Yet, limestones are normally poor in vanadium (Rankama and Sahama, 

1950, p. 600). Theoretically the +3 charge of vanadium is too high and its size (0.66 A) is too small to 

replace Ca+2 (0.99 A). Vanadium is reported to be 

strongly concentrated in clay and organic matter 

(Krauskopf, 1955; Tourtelot, 1962, p. 46). Relations 

of vanadium in the Kansas samples seemed so anomalous that the calcite was leached from one sample 

with 0.1 N HC1; the insoluble residue and leachate 

were analyzed separately. The insoluble residue contained 0.07 percent vanadium and the leachate, 0.03 

percent vanadium. The whole sample (table 1, 220- 

to 225-foot depth) contained 0.05 percent vanadium. 

Vanadium, thus, is not concentrated in the calcite 

but rather in one of the insoluble constituents. The 

normal amounts of vanadium in the top two sample 

cuttings (table 1) and in the three surface samples 

of shale with low organic-carbon content (table 2, 

subunits 1, 21, 24) indicate that most of the vanadium in the Kansas samples is in the clay. Conditions 

that have affected the Niobrara sediments have 

somehow favored concentration of vanadium in the 

clay structures. A possible partial explanation is 

suggested by Le Riche (1959), who determined that, 

although the amount of vanadium in certain English 

shales closely parallels the amount of organic mat-
CHEMICAL COMPOSITION 37

ter, the vanadium actually occurs in the clay minerals. Le Riehe believed that vanadium was adsorbed 

on organic matter when the sediment was deposited 

but that it subsequently migrated into the structures 

of the clay minerals. The Niobrara samples contain 

nearly as much organic matter as the Sharon Springs 

samples but much less clay. If vanadium in the 

Niobrara sediments behaves as Le Riche suggested, 

fairly large amounts of vanadium originally adsorbed on organic matter would be concentrated in 

small amounts of clay and would give the anomalous 

relations observed, although, in all probability, the 

amount of vanadium would not be in excess of that 

in the Sharon Springs samples.

Niobium, zinc, silver, and lanthanum were detected in less than half the samples. The correlation 

coefficients calculated for niobium and zinc are, therefore, all weak and of limited significance. Neither 

correlation coefficients nor mean values have been 

calculated for lanthanum and silver. Lanthanum, like 

geochemically similar yttrium and ytterbium, is most 

concentrated in the apatite-rich carbonaceous shale 

at the top of the Sharon Springs (table 2, subunit 

21). Niobium's positive correlation coefficients are 

all with elements that occur in clays or associated 

elastics; like zirconium, which it resembles geochemically, niobium probably occurs in the clay minerals 

or zircon. Little can be inferred about the occurrence 

of zinc. Silver was detected spectrographically in 

only four samples, all of which contained exceptionally large amounts of organic matter where silver 

commonly is concentrated (Tourtelot, 1962, p. 61). 

The atomic-absorption values for silver (table 2) are 

considerably lower than those from the spectrographic method, but they also roughly parallel the 

reported amounts of organic matter.

In summary, the striking feature of the Kansas 

samples is the large number of elements associated 

primarily or almost exclusively with clay (table 6). 

Only iron, nickel, cobalt, and molybdenum occur 

in pyrite as well as clay. Only molybdenum definitely, probably uranium, and possibly also silver are 

strongly concentrated in organic matter. Only strontium is strongly concentrated in carbonates other 

than the concretions. That some elements inferred 

to occur predominantly in the clay minerals, such as 

manganese and barium, show relatively weak correlations with all elements suggests that small amounts 

may be disseminated in components other than clay. 

In the Kansas rocks, a concentration of elements such 

as copper, chromium, vanadium, cobalt, and possibly 

nickel is not evident in organic matter, although reported to be in other organic-rich shales (Krauskopf, 

1955, 1956; Tourtelot, 1962; Vine, 1966).

LEACHING OP SURFACE SAMPLES

Compared with subsurface shale samples (table 6), 

surface Sharon Springs samples are systematically 

depleted in several elements. Depletion of magnesium 

and calcium is partly due to leaching of dolomite. 

In addition, some calcium must have been removed 

from the clays. The observed depletion of iron, nickel, 

and cobalt is due to oxidation of pyrite. Some of 

the iron from the pyrite is retained in the surface 

rocks in jarosite. Manganese and strontium and, to 

a lesser extent, boron and lead are partly leached 

from the clays. Tourtelot (1962, p. 29 and 45) 

showed similar though smaller decreases in iron, 

calcium, magnesium, boron, manganese, strontium, 

and lead, but not nickel and cobalt, in a weathered 

outcrop of Pierre Shale. Vine (1966) reported depletion of iron, manganese, and cobalt in outcrop 

samples of Pennsylvanian black shale from Kentucky.

BENTONITES

Compared with the fresh shales, the two bentonites (tables 2, 6) contain slightly less magnesium, 

manganese, gallium, boron, ytterbium, and zirconium 

and much less of all the other elements, except silicon and aluminum. This small content, typical for 

several trace elements in most Pierre bentonites 

(authors' unpub. data), probably reflects the same 

leaching by unknown processes that has produced 

the kaolinite and abundant interlayer hydrated aluminum complexes that distinguish the Kansas Sharon 

Springs bentonites from most other bentonites.

COMPARISON WITH OTHER SHALES

The elements in the Kansas samples of Pierre 

Shale are compared with those of four other groups 

of shale in figure 25.

Major Elements

Aluminum, iron, and sodium in all groups of shale 

are about the same. Turekian and Wedepohl's silicon 

value for shale seems abnormally low. Potassium in 

the Kansas Sharon Springs samples, which is higher 

than that in Tourtelot's Pierre samples, reflects the 

more illitic character of the mixed-layer clays typical 

of the Sharon Springs shales as compared with the 

more montmorillonitic shales of the Pierre as a whole.

Calcium in the Kansas samples, which is higher 

than in Tourtelot's samples, reflects the presence of 

several percent of dolomite in samples from the 

unweathered cuttings. The expected, but unobserved, 

difference in magnesium content that would be 

caused by the presence of dolomite must be offset 

by lesser amounts of magnesium in the clay components of the Kansas samples.
38 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Minor and Trace Elements

Many of the differences in minor- and trace-element contents between the groups of samples reported 

in figure 25 seem to be controlled by two interrelated 

factors content of organic matter and grain size. 

Krauskopf's black shale group is generally the most 

organic rich, having contents ranging from a few 

percent to over 50 percent. The Kansas Sharon 

Springs samples generally have contents of 5-10 percent. Most of Tourtelot's Pierre samples are from 

members of the Pierre that contain relatively little 

organic matter. The grain size of most Pierre rocks is 

exceptionally fine, and that of the organic-rich shales 

of Krauskopf, even finer. Thus, both the Pierre and 

Krauskopf's black shale are likely to be finer grained 

than the ordinary shales. The finer grained rocks and, 

indirectly, the more carbonaceous shales thus should 

be depleted in elements concentrated in coarser or 

heavier detrital mineral grains.

In figure 25, element content is related to organic 

content or to grain size in the following ways. The 

general ranges of contents given by Turekian and 

Wedepohl and by Krauskopf for many elements in 

common shales and by Krauskopf for black shales 

overlap, but for most elements the average contents 

in the black shale extend either below (indicating 

a grain-size control) or above (indicating organicmatter control) the range of contents for common 

shale. Trace-element content in most of the Kansas 

shales centers near the end of the range for common 

shale, beyond which the trace-element average content of black shale extends farthest. For elements 

whose ranges of contents in common shale and black 

shale do not overlap, the content of the Kansas shales 

commonly falls between those two ranges. Thus the 

contents of the Kansas samples are about what would 

be expected in moderately carbonaceous shales, which 

they are. Elements in Tourtelot's Pierre samples 

whose concentrations differ appreciably from those 

in the Kansas shales (manganese, gallium, molybdenum, nickel, lead, vanadium, zirconium) are more 

like those in the ordinary shales. Elements which 

show no strong affinities for organic matter, for pyrite, or for heavy minerals commonly are about 

equally abundant in all the categories of shale for 

which data are available.

Titanium, zirconium, and niobium contents in ordinary shale that are notably larger than in the other 

three categories reflect the larger average grain size 

of ordinary shale and thus of heavier elastics, such 

as zircon, anatase, and ilmenite, in which these elements should occur.

Manganese is conspicuously less abundant in the 

Pierre samples than in ordinary shale. Heavy manganese oxides in coarser rocks are exceptionally 

sparse in the finer grained Pierre samples. The small 

amounts of manganese in shales of the Pierre occur 

mainly in clay structures.

The slightly higher lead content in the Kansas 

Sharon Springs than in Tourtelot's Pierre samples 

probably follows from its substitution for K+ in the 

more illitic Sharon Springs samples.

Molybdenum, uranium, silver, nickel, copper, vanadium, and gallium, as shown in figure 25, all appear to be concentrated in organic-rich shales. The 

reason for the higher contents of molybdenum, uranium, and silver in the more carbonaceous rocks 

seems obvious.

Nickel and copper are only slightly more abundant 

in the Kansas shales than in Tourtelot's Pierre samples or in most ordinary shales. The higher nickel 

content is due mainly to the relatively large amount 

of nickel-bearing pyrite. No similar explanation is 

evident for copper in the Kansas samples, although 

in other rocks copper commonly is concentrated in 

pyrite or organic matter (Tourtelot, 1962, p. 46). 

Although cobalt, like nickel, has been inferred to 

occur in pyrite in the Kansas samples, the expected 

high cobalt content relative to that in other shales 

is not evident.

Vanadium content of the four groups of shales is 

entirely consistent with the occurrence of the element in organic matter, where it is thought to be 

concentrated (Krauskopf, 1956, p. 29; Tourtelot, 

1962, p. 46). As previously explained, the relation 

with organic matter may be indirect; the vanadium 

may actually be in the clay-mineral fraction of some 

sediments.

Gallium is generally most abundant in Krauskopf's 

black shale and least abundant in Tourtelot's Pierre 

samples and the ordinary shales. This relation indicates gallium concentration in organic matter. The 

correlation statistics for the Kansas samples, however, and the well-established fact that gallium replaces aluminum in clay (Goldschmidt, 1954, p. 319) 

strongly contradict this interpretation. A possible 

explanation might be a higher percentage of clay, 

and hence a greater amount of gallium substituted 

for aluminum, in finer grained shales rich in organic 

matter. Such an explanation, however, does not apply 

well to the Kansas samples, because they are only a 

little over 50 percent clay, which, if anything, is 

slightly less than average for the Pierre Shale in 

general. The large amount of gallium in the Kansas 

samples cannot be explained at this time.

Barium, cobalt, chromium, scandium, yttrium, and 

ytterbium occur in approximately equal concentrations in the Kansas and the other groups of samples,
MEASURED SECTIONS 39

as expected from their inferred occurrence in the 

clays. Yttrium and ytterbium, being closely related to 

the rare earths, might be expected to occur in heavy 

clastic mineral grains like monazite and thus be depleted like titanium, zirconium, and niobium in the 

finer grained groups of rocks. No such depletion is 

evident, and the yttrium and ytterbium apparently 

occur in clays.

MEASURED SECTIONS

Seven partial surface sections and two well logs 

of the Sharon Springs Member of the Pierre Shale 

were measured in Wallace, Logan, and Phillips Counties, Kans. Five of the sections represent a part of 

the dark soft shale unit and two represent the upper 

part of the organic-rich shale unit and the phosphatic shale unit. Sample logs of two test holes, 

drilled by the State Geological Survey of Kansas to 

determine the thickness and character of the Sharon 

Springs, are included with the measured sections.

LOCALITY 1. Section of the lower unit of the Sharon Springs 

Member of the Pierre Shale and the upper part of the 

Smoky Hill Chalk Member of the Niobrara Formation

[Exposure measured in the valley of Burris Draw in the NE^NE1^ sec. 20, 

T. 15 S., R. 32 W., Lake McBride 7%-minute quadrangle, Logan County, 

Kans.]

Pierre Shale (lower part) : Feet 

Sharon Springs Member (lower unit) :

42. Shale, light-gray; oxidizes to dark yellowish orange. Tan-weathering gray 

irregularly shaped limestone concretions 0.3 ft thick by 0.8 ft wide 2 ft 

above base .................................................. 8.0

41. Limestone concretions, dark-yelloworange; has white calcareous specks; 

marly, weathering in thin slabs; persistent; forms lenses as long as 6 ft. 

Fossiliferous, containing poorly preserved baculites and pelecypods (USGS 

Mesozoic loc. D1827). Fossils: Inoceramus cf. /. subcompressus Meek and 

Hayden, Pteria sp., Ostrea sp., Baculites obtusus Meek. (See pi. 1) .............. .4

40. Shale, light- to medium-gray; soft, weathering to fine flaky crust; 0.2-ft-thick 

limonite-gypsum layer at base contains 

fragments of large thin-shelled inocerams (USGS Mesozoic loc. D2691). 

Fossils: Inoceramus aff. /. cycloides 

Wegner. (See pi. 2)................................ 12.6

39. Shale, like subunit 42 ................................ 9.6

38. Shale, like subunit 40 ................................ 3.0

37. Shale, like subunit 42 ................................ 3.7

36. Shale, light-olive-gray; weathers dusky 

yellow to gray; soft, weathering to fine 

flaky crust; a few thin ferruginous 

streaks; poorly exposed; slightly bentonitic except in heads of some gullies 24.9

Pierre Shale (lower part) Continued feet 

Sharon Springs Member (lower unit) Continued 

35. Shale, light-olive-gray; hard in lower 

part; weathers to small chips and 

plates; becomes very soft in upper part; 

contains very sparse fish scales ............ 17.4

34. Bentonite parting, white ............................ .02

33. Shale, dusky-yellowish-brown; hard, fissile to papery weathering; abundant 

fish scales and bones; contains gypsum 

and jarosite on fracture surfaces and 

bedding planes; also contains selenite 

crystals ...................................................... 6.8

32. Bentonite, white .......................................... .01

31. Shale, like subunit 33 .................................. 1.0

30. Bentonite, light-gray to white .................... .02

29. Shale, black; weathers platy and light 

olive gray to light gray, blocky; thin 

calcareous streaks .................................... 1.8

28. Bentonite, yellowish-gray, nonswelling, 

granular, persistent; sharp lower contact and gradational upper contact ...... .2

27. Shale, black to grayish-black; noncalcareous; brownish-gray clayey calcareous shale streaks; 0.2-ft-thick bed of 

gray clay 0.5 ft below top. Contains a 

few fragments of inoceramid shells 

(USGS Mesozoic loc. D5510). Fossils: 

Inoceramus sp .......................................... 2.7

Total lower unit of Sharon Springs

Member measured ............................ 92.2

Niobrara Formation (part) : : Smoky Hill Chalk Member (part) :

26. Bentonite, dark-yellowish-orange, nonswelling; color results from limonite 

that coats bedding and fracture surfaces; contains abundant selenite crystals and hairline black-shale streaks.... .1

25. Shale, dark-gray; weathers medium gray; 

calcareous, abundant white calcareous 

specks ........................................................ 2.5

24. Bentonite, like subunit 26; contains blackshale streaks cemented in limonite........ .05

23. Marlstone, dark-gray; weathers medium

gray; shaly, deeply weathered, soft .... 2.3

22. Bentonite, like subunit 24 .......................... .03

21. Marlstone, like subunit 23 .......................... 2.3

20. Bentonite, like subunit 26; contains blackshale streaks .............................................. .1

19. Marlstone, medium-dark gray; weathers

very pale orange; very shaly ................ 1.2

18. Bentonite parting, like subunit 26 .......... .03

17. Marlstone, like subunit 19 .......................... .8

16. Bentonite, like subunit 26; contains limonite streaks ............................................. .1

15. Marlstone, like subunit 19 ........................ 1.4

14. Bentonite parting, like subunit 26 .......... .03

13. Marlstone, like subunit 19 .......................... 2.2

12. Bentonite parting, like subunit 26 ............ .05

11. Marlstone, like subunit 19 ........................ 1.9

10. Bentonite, moderate-yellowish-brown, 

nonswelling; abundant pyrite nodules, 

limonite, and gypsum throughout; oxidized pyrite nodules enclose soft white 

kaolinlike nodules .................................... .2
40 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Niobrara Formation (part) Continued

Smoky Hill Chalk Member (part) Continued

Feet

4. 

3.

Marlstone, like subunit 19 .......................... 2.1

Bentonite, moderate-yellowish-brown, 

nonswelling, granular, deeply weathered; persistent bed ................................ .5

Marlstone, like subunit 19 .......................... 2.7

Bentonite parting, calcareous, like subunit 8 .......................................................... .03

Chalk, medium-dark-gray; weathers very 

pale orange; hard-ledge former; clayey; 

abundant white calcareous specks and 

numerous fresh pyrite nodules .............. 5.8

Bentonite, like subunit 8 ............................ .05

Chalk, light-olive-gray; weathers light 

gray; hard; clayey; slabby to chunky; 

abundant fresh and weathered pyrite 

nodules ........................................................ 7.0

Bentonite, like subunit 8.............................. .05

Chalk, like subunit 3 .................................. 15+

Total Smoky Hill Member measured 48.5

LOCALITY 2. Partial section of the Pierre Shale

[Measured at McAllaster Buttes, in the SE% sec. 13, T. 12 S., R. 37 W., 

Logan County, Kans.]

Pleistocene deposits, not measured. feet 

Pierre Shale (part) :

Weskan Member (part) :

38. Covered, in part greenish-brown shale 

that weathers black and contains sparse 

rusty-weathering siderite concretions.... 20.0

37. Shale, greenish-black, soft; limestone concretions in lower part of this subunit.... 25.0

36. Bentonite, white, nonswelling .................... 1.0

35. Shale, grayish-green, soft .......................... 2.0

34. Bentonite, reddish-brown, nonswelling...... .7

33. Shale, very dark gray; weathers light 

gray, having a fine-textured soft crust; 

soft .............................................................. 6.0

32. Bentonite, cream to light-tan, granular, 

nonswelling; limonite and jarosite 

stained. Contains abundant gypsum in 

form of selenite crystals ........................ .1

31. Clay, olive-gray, plastic .............................. .2

30. Bentonite, like subunit 32 .......................... .15

29. Clay, like subunit 31 .................................. .1

28. Siderite concretions, reddish-brownweathering; 0.4 ft thick by 1.5 ft in 

diameter .................................................... .4

27. Shale, dark-gray; weathers light gray;

soft; flaky ................................................ 2.0

26. Bentonite, like subunit 32 .......................... .5

25. Shale, like subunit 27 ................................ 1.2

24. Bentonite, like subunit 32 .......................... .05

23. Clay, like subunit 31 .................................... .25

22. Bentonite, white .......................................... .03

21. Clay, like subunit 31 .................................. .4

20. Shale, like subunit 27; has a few phosphate nodules at base .............................. 2.4

19. Limestone, concretionary, shaly to laminated; dark gray, weathering tan to

Pierre Shale (part) Continued feet 

Weskan Member (part) Continued

rusty yellow; lenslike; 1.0 ft thick by

20 ft in diameter ...................................... 1.0

Total Weskan Member measured

(rounded) .......................................... 63.5

Sharon Springs Member (upper unit) : ^^==^ 

18. Bentonite, white, nonswelling .................... .02

17. Shale, black, hard, hackly; not buttress

forming ...................................................... 3.0

16. Bentonite, like subunit 18; has horizon of 

gray limestone concretions 0.3 ft thick 

by 1.0 ft in diameter ................................ .05

15. Shale, like subunit 17 .................................. 1.3

14. Bentonite, like subunit 18 .......................... .1

13. Shale, like subunit 17 .................................. 2.0

12. Bentonite, like subunit 18 .......................... .02

11. Shale, dark-brownish-black, hard, flaky 

to papery; abundant scales and other 

fish remains. Weathers grayish brown 

and in thicker units weathers to form 

vertical buttresses .................................... .3

10. Shale, like subunit 11; has eight layers of 

dark-bluish-gray-weathering phosphate 

nodules. Some brown shale nodules having concentric bands or rinds of gypsum. Most nodules contain abundant 

fish scales and bones and possibly fecal 

pellets. Contains four thin bentonite 

streaks ........................................................ 3.5

Total upper unit of Sharon Springs

Member measured (rounded) ........ 10.3

Sharon Springs Member (middle unit) : =====

9. Bentonite, cream to light-tan, nonswelling, granular .....................................- .25

8. Shale, like subunit 11; has five light-gray

bentonite streaks ...................................... 3.7

7. Shale, like subunit 11; gray tan-weathering limestone concretion layer 0.8 ft 

thick by 3-5 ft in diameter 6 ft above 

base; dark-gray limestone concretion 

with tan cone-in-cone structure 12 ft 

above base ................................................ 17.0

6. Limestone concretions, septarian, 3 ft 

thick by 9 ft in diameter; contains thick 

septa of light-brown fibrous calcite .... 3.0

5. Shale, like subunit 11; crisscrossed with 

veins of gypsum, jarosite, and limonite. 

Sparse dark-gray white-weathering 

dense limestone concretions 0.6 ft thick 

by 1.5 ft in diameter at 10, 13, and 15 

ft above base. Concretions are of irregular shape and have 0.02-ft-thick 

gypsum crusts. At 18 ft above base is 

a layer of gray sparsely fossiliferous 

septarian limestone concretions 1 ft 

thick by 2 ft in diameter containing a 

few specimens of Baculites asperiformis 

Meek .......................................................... 25.0

4. Bentonite, cream-colored, nonswelling, 

granular; jarosite and limonite stained; 

containing abundant gypsum ................ .2

3. Shale, like subunit 11; contains a highly 

fossiliferous limestone concretion 1 ft
MEASURED SECTIONS 41

Pierre Shale (part) Continued Feet 

Sharon Springs Member (upper unit) Continued 

thick by 6 ft in diameter (USGS Mesozoic loc. D2591). Fossils: Inoceramus 

sp., Ostrea inornata Meek and Hayden, 

Baculites asperiformis Meek, Trachyscaphites spiniger (Schluter) subsp. 

porchi Adkins. (See pi. 2.)-- - 13.0

2. Shale, like subunit 11; poorly exposed...... 28.5

1. Bentonite, poorly exposed .......................... .4

Total middle unit of Sharon Springs

Member measured (rounded) ............ 91.0

Total Sharon Springs Member measured 101.3

Total Pierre Shale measured ................ 164.8

LOCALITY 2. Sample log of test hole McAllaster Buttes 1 State

[Drilled in the SW%NE% sec. 13, T. 12 S., R. 37 W., Logan County, Kans. 

Hole collared at about 100 feet below the contact between the Weskan and 

Sharon Springs Members of the Pierre Shale. Sampled and described by 

W. A. Cobban]

Pierre Shale:

Sharon Springs Member (samples start at 

45 ft) :

Shale, medium-gray; slightly calcareous in places and has a few white 

specks; contains a few shell fragments. A medium-gray finely pyritic 

layer of bentonite at 55-60 ft .......... 15

Shale, medium-gray; contains minute 

black carbonaceous specks and, here 

and there, white calcareous specks, 

bits of mollusks, or brown fish scales 30

Shale, medium-gray; calcareous where 

white specks are concentrated as 

thin laminae ........................................ 5

Thickness Depth 

(feet) (feet)

60

90

95

Total Sharon Springs Member 

drilled ............................................ 95

Niobrara Formation:

Smoky Hill Chalk Member:

Shale, light-medium-gray, firm; very 

calcareous, abundant white specks; 

contains a few fish scales. Traces of 

white bentonite and bluish-gray pyritic bentonite ...................................... 5

Shale, light-medium-gray; slightly 

lighter than overlying subunit; firm; 

very calcareous, abundant white 

specks. Sparse pyrite ........................ 5

Shale, medium-light-gray, very calcareous. A little white bentonite .......... 5

Shale, light-gray; very calcareous, 

abundant white specks ...................... 50

Shale, like overlying subunit. Hard 

layer at 163 ft. A little bluish-gray 

bentonite .............................................. 5

Shale, light-gray; very calcareous, 

abundant white specks. Trace of bluish-gray pyritic bentonite in lower 

5 ft ........................................................ 45

100

105

110

160

165

210

Total Smoky Hill Member drilled.. 115

LOCALITY 3. Partial section of the lower unit of the Sharon 

Springs Member of the Pierre Shale

[SEi,i sec. 20, T. 12 S., R. 36 W., Logan County, Kans. Measured along 

the south meander scar of the North Fork of the Smoky Hill River]

Pierre Shale (part) : Feet 

Sharon Springs Member (lower unit) :

16. Soil and deeply weathered shale .............. 3.0

15. Bentonite, light-orange-brown; much limonite stain .............................................. .5

14. Shale, dark- to medium-gray, soft; upper 

5.5 ft weathers brownish gray, lower 

2 ft weathers light gray; coarsely laminated appearance .................................... 7.5

13. Shale or ferruginous mudstone, limonitic, 

orange-brown, fossiliferous; contains 

fragmentary inocerams and baculites 

(USGS Mesozoic loc. D2690). Fossils: 

Inoceramus aff. /. barabini Morton, 

Baculites obtusus Meek .......................... .3

12. Bentonite, dark-orange-brown .................. .25

11. Shale, dark- to medium-gray; weathers

gray; soft .................................................. 1.4

10. Bentonite parting ........................................ .02

9. Shale, like subunit 11 ................................ 3.3

8. Bentonite parting ........................................ .01

7. Shale, like subunit 11 ................................ .3

6. Bentonite parting ........................................ .01

5. Shale, like subunit 11 ................................ .3

4. Bentonite, cream to light-gray; limonite

stain ............................................................ .15

3. Shale, like subunit 11 ................................ 4.7

2. Shale, light-gray-brown; weathers dark 

gray to gray brown; hard, platy to 

chippy; abundant jarosite ...................... 4.8

1. Shale, like subunit 11 ................................ 2 +

Covered.

Total lower unit of Sharon Springs 

measured (rounded) ........................ 28.5

LOCALITY 4. Section of the lower unit of the Sharon Springs 

Member of the Pierre Shale and the upper part of the 

Smoky Hill Member of the Niobrara Formation

[Measured in the SW%SE% sec. 33, T. 12 S., R. 36 W., Logan County, 

Kans. Section started in Niobrara about 100 yards due west of dry oil 

and gas test hole and continued north along the southwest bank of the 

North Fork of the Smoky Hill River]

Pleistocene deposits, not measured. 

Pierre Shale:

Sharon Springs Member (lower unit) :

20. Shale, gray; weathers light tannish 

brown; soft; flaky; 0.2-ft-thick rusty 

bentonite 3 ft above base ........................ 8

19. Shale, dark-gray, soft, poorly exposed; 

one or two bentonites near base. A 1-ft 

bentonite bed 15 ft above base contains 

thin white limestone concretions; a 

questionable bentonite at about 19 ft 

above base ...................................... .. . 23

18. Shale, bluish-black, hard; weathers papery; rich in organic matter; abundant 

fish remains ............. ................... ........ 12

17. Shale, dark-gray, bentonitic, soft; abundant jarosite throughout ........................ 2

Feet
42 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Pierre Shale Continued feet 

Sharon Springs Member (lower unit) Continued 

16. Shale, dark-brownish-gray; slightly 

harder than underlying shales; abundant fish remains .................................... 3

Total lower unit of Sharon Springs 

Member measured ............................ 48

Niobrara Formation (part) :

Smoky Hill Chalk Member (part) :

15. Bentonite, white to cream, nonswelling,

granular .................................................... 0.1

14. Shale, gray-brown, calcareous, fissile; 

abundant white calcareous specks .....

13. Bentonite parting .......................................

Shale, like subunit 14; brownish gray ... 

Bentonite parting .......................................

12. 

11. 

10.

4.0

.05 

1.9

.05

Shale, like subunit 14 ................................ 1.5

9. Bentonite parting 

8.

.05

Shale, like subunit 14 ................................ 1.2

7. Bentonite, cream; contains white nodules 

of kaolin (?) 0.1 ft thick by 0.15 ft in 

diameter; heavy limonite crust at top 

and base of bed ........................................ .15

6. Shale, dark-gray; weathers bluish gray; 

calcareous; flaky; abundant pyrite 

nodules ...................................................... 5.0

5. Shale, cemented with limonite .................. .2

4. Bentonite, gray; contains hairline blackshale streaks ............................................ .1

3. Shale, dark-gray; weathers bluish gray;

calcareous; thin limonite layer at top.. .3

2. Bentonite, white, nonswelling; with 0.05- 

ft-thick limonite layer at top, 0.02-ftthick layer at base .................................. .4

. Marlstone, dark-gray; weathers bluish gray 

and shaly. Several zones of altered pyrite nodules and yellow chalk streaks; 

pyrite nodules 3 ft above base, pyrite 

nodules and chalk layer 7 ft above base, 

layer of pyrite nodules 8 ft above base 12.0 

Total Smoky Hill Member measured 27.0

LOCALITY 5. Section of the lower unit of the Sharon Springs 

Member of the Pierre Shale and the upper part of the 

Smoky Hill Member of the Niobrara Formation

[Measured in the SB%NB% sec. 32, T. 13 S., R. 37 W., Logan County, Kans.]

Pierre Shale (part) : Feet 

Sharon Springs Member (lower unit) :

41. Shale, dark-gray to black; mostly covered

by gravel .................................................... 10.0

40. Bentonite, cream to light-yellow, granular, nonswelling .................................... .15

39. Shale, dark-gray-brown, clayey, soft,

poorly exposed, highly weathered ........ 2.0

Bentonite, like subunit 40 ........................ .15

Shale, like subunit 39 ................................ .25

Bentonite, like subunit 40 ........................ .2

38. 

37. 

36. 

35. 

34. 

33.

Shale, like subunit 39 ................................ 1.0

Bentonite, like subunit 40 ........................ .4

Shale, like subunit 39 ................................ 1.5

Pierre Shale (part) Continued Feet 

Sharon Springs Member (lower unit) Continued

32. Bentonite, like subunit 40 ........................ .05

Shale, like subunit 39 ................................ .8

Bentonite, like subunit 40 ........................ .01

Shale, like subunit 39 ................................ .6

Bentonite, like subunit 40 ........................ .5

31. 

30. 

29.

28.

27. Shale, like subunit 39 ................................ 3.3

26. Bentonite, like subunit 40 .25

25. Shale, like subunit 39 ................................ 1.0

24. Bentonite, like subunit 40; true thickness

indeterminate ............................................ 1.0

23. Shale, like subunit 39 ................................ 8.0

Total lower unit Sharon Springs

Member measured (rounded) 31.2

Niobrara Formation (part) :

Smoky Hill Chalk Member (part) :

22. Shale, medium- to light-gray; has thin

calcareous streaks .................................... 3.5

21. Bentonite, like subunit 40; orange ............ .3

20. Shale, black, hard, weakly calcareous;

contains a few white specks ................ 4.0

19. Bentonite, like subunit 21 ........................ .2

18. Marlstone, bluish-gray, shaly; yellow to

orange on deeply weathered surface.... 5.7

17. Bentonite, like subunit 21 ........................ .1

16. Marlstone, like subunit 18; has a 0.03-ftthick bentonite bed 1.5 ft below top .... 3.4

15. Bentonite, like subunit 21 ........................ .05

14. Marlstone, like subunit 18 ........................ 4.0

13. Bentonite, like subunit 21 ........................ .1

12. Marlstone, like subunit 18; has two zones

of 0.1-ft-thick pyrite nodules ................ 3.7

11. Bentonite, like subunit 21 ........................ .2

10. Marlstone, like subunit 18 ........................ 1.2

9. Bentonite, gray, nonswelling; abundant

gypsum and jarosite ................................ .4

8. Marlstone, like subunit 18 ........................ 2.5

7. Chalk, compact, yellow, lenticular .......... 1.0

6. Marlstone, like subunit 18 ........................ 7.5

5. Limonite layer, brown, persistent ............ .02

4. Marlstone, like subunit 18; contains numerous weathered pyrite nodules ........ 2.4

3. Chalk, like subunit 7 .................................. .4

2. Limonite layer, like subunit 5 .................. .2

1. Marlstone, like subunit 18 ........................ 5.0

Covered.

Total Smoky Hill Chalk Member 

measured (rounded) ........................ 45.9

LOCALITY 6. Section of the lower unit of the Weskan and 

the upper unit of the Sharon Springs Members of the 

Pierre Shale

[Measured at Devils Halfacre, in the SW^iSE^iNW^i sec. 36, T. 13 S., 

R. 40 W., Wallace County, Kans.]

Pierre Shale (part) : Feet 

Weskan Member (lower unit) :

27. Siderite concretion; weathers dark yellowish orange to dusky red .................... .05

26. Shale, greenish-black to olive-gray, poorly

exposed ........................... .. . ............... 7.0
MEASURED SECTIONS 43

Pierre Shale (part) Continued feet 

Weskan Member (lower unit) Continued

25. Limestone concretions, dark-gray; weather to light-gray small chips and angular fragments; septarian; fossiliferous 

(USGS Mesozoic loc. D1177). Fossils: 

pelagic Foraminifera, Inoceramus sublaevis Hall and Meek, Pteria linguaeformis (Evans and Shumard), Ostrea 

inornata Meek and Hayden, Anisomyon 

cf. A. borealis (Morton), Drepanochilus sp., Odontobasis? sp., Oxybeloceras 

sp., fish scales .......................................... 1.0

24. Shale, like subunit 26; bentonitic; thin 

bentonite bed near base, 0.5-ft-thick 

bed of moderate-red bentonite near top; 

poorly exposed .......................................... 6.0

23. Limestone concretion, grayish-orange, 

tabular, slabby, fossiliferous (USGS 

Mesozoic loc. D1176). Fossils: pelagic 

Foraminifera, Inoceramus aff. /. proximus Tuomey, Baculites sp., Didymoceras n. sp., fish scales............................ .4

Total Weskan Member measured

(rounded) .......................................... 14.5

Sharon Springs Member (upper unit) : ^===

22. Gypsum, fibrous, and white soft chalky

basaluminite .............................................. 0.2

21. Shale, grayish-brown; lower 3 ft hard 

and chippy, upper 1.5 ft soft; thin 

layer of phosphate nodules in lower 

1 ft .............................................................. 4.5

20. Bentonite, very pale orange, hard ............ .01

19. Shale, grayish-brown; weathers light 

gray; hard; phosphatic(?) ; contains 

one layer of small phosphate nodules.... .6

18. Bentonite, like subunit 20 ........................ .05

17. Shale, like subunit 19; abundant large

fish scales .................................................. .4

16. Bentonite, like subunit 20 .......................... .05

15. Shale, medium-dark-gray to dark-gray; 

weathers papery to flaky in lower 2.4 

ft, becoming grayish brown with hackly 

fracture in upper 5 ft; abundant jarosite throughout. Eight layers of gypsum-encrusted clayey phosphate nodules which range from 0.05 to 0.3 ft 

in diameter and contain rounded fragments of bones and abundant lightblue-weathering fish scales .................... 7.4

Total upper unit of Sharon Springs 

Member .............................................. 13.2

Sharon Springs Member (middle unit) : ==^=^

14. Bentonite, grayish-yellow, soft, nonswelling; limonite stain on fractures; abundant large selenite crystals throughout 0.4

13. Shale, grayish-black, hard, buttress-forming; weathers brownish black and 

papery; abundant fish scales and occasional vertebrate remains; rich in 

organic matter; abundant jarosite on 

bedding planes and fracture surfaces. 

Upper 0.6 ft contains 0.05-ft-thick layer 

of clayey phosphate nodules and 0.01- 

ft-thick bentonite parting ...................... 1.75

11. 

10.

9.

8.

7.

6.

5.

4.

Pierre Shale (part) Continued Feet 

Sharon Springs Member (middle unit) Continued

12. Bentonite, like subunit 14 ........................ .25

Shale, like subunit 13 ................................ 1.1

Bentonite, like subunit 14 ........................ .15

Shale, like subunit 13 ................................ 1.2

Bentonite, like subunit 14 ........................ .05

Shale, like subunit 13 ................................ .6

Bentonite, like subunit 14 ........................ .1

Shale, like subunit 13. Has sparse septarian limestone concretions containing white calcite septa and sparse gray 

to pale-blue barite crystals .................... 1.0

Limestone concretions, septarian, darkgray, spherical, closely spaced; 

weather light gray; thick septa of 

dark-brown fibrous calcite coated with 

transparent calcite crystals. Two or 

more concretions may join to form lenslike masses of limestone 20 ft or more 

in diameter. Thick crusts of cone-incone limestone coat a few of the concretions ...................................................... 2.5

Shale, like subunit 13 ................................ 2.4

Limestone concretions, like subunit 4...... 1.0

Shale, like subunit 13 ................................ 3 +

Total middle unit of Sharon Springs

Member measured ............................ 15.5

3. 

2. 

1.

Total Sharon Springs measured ...... 28.7

Total Pierre Shale measured ............ 43.1

LOCALITY 6. Sample log of test hole Guy Holland 1 State, 

Devils Half acre

[In the SE%SE%NW% sec. 36, T. 13 S., R. 40 W., Wallace County, Kans. 

Ground elevation 3,440 feet. Hole collared at the contact of the Weskan 

and Sharon Springs Members of the Pierre Shale. Sampled and described 

by W. A. Cobban]

Pierre Shale:

Sharon Springs Member (upper unit) :

Shale, yellowish-gray; mottled mediumlight-gray; weathered; contains 

black fish scales and bones................

Shale, medium- to medium-dark-gray; 

has minute yellowish-gray specks.... 

Sharon Springs Member (middle and lower 

units) :

Shale, medium-dark-gray and mediumolive-gray; mottled lighter brown; 

contains brown fish scales and bones. 

A little medium-bluish-gray minutely 

pyritic nonswelling bentonite and 

very pale orange to white very finely 

micaceous (white) nonswelling bentonite ....................................................

Shale, medium-dark-gray; contains a 

few brown fish scales. A little bluishgray and white bentonite ..................

Shale, medium-dark-gray; contains fish 

scales and bones. Much pale-bluishgray bentonite ......................................

Thickness 

(feet)

Depth 

(feet)

5

10

15

20

25
44 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

Pierre Shale Continued Thickness 

(feet)

Depth 

(feet)

Shale, medium-dark-gray; contains a 

few fish scales and bones. At 27-29 

ft a medium-dark-gray septarian 

limestone concretion has brown to 

white calcite veins which contain 

some large crystals of nearly colorless calcite ............................................ 5

Shale, medium-dark-gray; not as dark 

as 10- to 30-ft subunits; contains 

minute black carbonaceous specks 

and a few fish scales .......................... 20

Shale, like overlying subunit; contains 

a bed of white bentonite .................... 5

Shale, medium-dark-gray; contains minute black carbonaceous specks and 

a very few fish scales and bits of 

mollusk shell. Some laminae of gray 

siltstone in lower 10 ft ...................... 40

Shale, medium-gray; contains a layer 

of white swelling bentonite .............. 5

Shale, medium-gray; contains carbonaceous specks and, here and there, 

bits of mollusks or white calcareous 

specks. Some white bentonite at 125- 

130 ft and 135-140 ft. Few fragments of inoceramid and baculitid 

shells at 130-135 ft ............................ 50

Shale, medium-gray; contains some 

white calcareous specks locally concentrated as thin laminae. Fish 

scales and bones moderately common. Some white bentonite at 155- 

160 ft. At 170-171 ft a medium-gray 

limestone concretion contains white 

specks and septarian concretions 

having thin white calcite veins ........ 35

Shale, medium-gray; calcareous in 

parts having white specks. Traces 

of bluish-gray minutely pyritic bentonite; fragments of inoceramid 

shells ...................................................... 5

Shale, medium-gray; in part calcareous. Subunit contains a thin brown 

sideritic concretion ............................ 5

Shale, medium-gray, calcareous; contains white specks. Some mediumbluish-gray minutely pyritic 

bentonite in lower 5 ft ...................... 10

Shale, medium-gray; gradually becomes lighter downward; very calcareous, abundant white specks; 

contains a few fish scales. A little 

medium-gray to bluish-gray bentonite at 220-222 ft. (Approximate 

contact between Pierre Shale and 

Niobrara Formation picked on the 

electric log at 222 ft) ........................ 17

Total middle and lower units of 

Sharon Springs Member measured .............................................. 222

30

50

55

95

100

150

185

190

195

205

222

Niobrara Formation:

Shale, same as overlying subunit ................ 13

Shale, medium-light-gray; very calcareous, 

abundant white specks; contains a few 

fish bones. Some medium-bluish-gray 

bentonite at 245-250 ft .............................. 20

Shale, medium-light-gray; slightly darker 

than overlying subunit; very calcareous, 

abundant white specks. A little bluishgray bentonite in upper 20 ft .................. 45

Total Niobrara Formation measured.. 78

Thickness Depth 

(feet) (feet)

235

255

300

Section of lower unit of Sharon Springs Member

[Measured by J. R. Gill and W. A. Cobban on the east bank of Prairie Dog 

Creek about 1 mile east of the town of Long Island in the E%SE*4 

sec. 24, T. 1 S., R. 20 W., Phillips County, Kans.]

Pierre Shale (part) : *"««* 

Sharon Springs Member (lower unit) :

33. Bentonite; bright orange at base, pale

yellowish gray at top, nonswelling ...... 0.3

32. Shale, medium-dark-gray; weathers flaky 6.9 

31. Ash, light-yellow, medium-grained, calcareous ........................................................ .1

30. Bentonite, yellowish-orange ...................... .05

29. Shale, medium-dark-gray; contains 0.1- 

ft-thick layer of phosphate nodules 

about 1 ft above base. Limestone concretion 0.2 ft thick by 0.05 ft in diameter about 1.5 ft below top; thin 

light-orange-weathering limonite plates 

throughout ................................................ 5.0

28. Bentonite, pale-yellowish-gray, ashy ...... .1

27. Shale, like subunit 32 ................................ 1.7

26. Bentonite; weathers orange; nonswelling .1 

25. Shale, like subunit 32 .................................. 1.1

24. Bentonite, dark-gray, waxy, nonswelling .2 

23. Shale, like subunit 32 ................................ 2.6

22. Bentonite; basal 0.15 ft weathers bright 

orange, upper 0.45 ft weathers pale 

yellowish gray; waxy, nonswelling ...... .55

21. Shale, like subunit 32 ................................ 1.2

20. Bentonite, pale-yellowish-gray, waxy ...... .6

19. Shale, like subunit 32 .................................. .9

18. Bentonite, impure; limonite stain ............ .05

17. Shale, like subunit 32 ................................ .6

16. Bentonite, pale-yellowish-gray .................. .02

15. Shale, like subunit 32 .................................. 2.2

14. Bentonite, pale-yellowish-gray, waxy, nonswelling; mottled with orange and 

brown iron stain ...................................... .6

13. Shale, like subunit 32 ................................ 3.3

12. Shale, dark-gray .......................................... 1.5

11. Bentonite, gray; mottled with brightorange iron stain; nonswelling ............ .5

10. Shale, olive-gray; grades upward into 

medium dark gray; weathers into small 

chips .............................................- ....--. . 1.0

9. Shale, medium-light-gray, calcareous; 

weathers yellowish gray to pale yellowish gray; has hackly fracture; contains 

limonite-cemented bentonite layer 0.01 

ft thick 1.8 feet above base .................... 5.5
REFERENCES CITED 45

Pierre Shale (part) Continued feet 

Sharon Springs Member (lower unit) Continued

8. Bentonite, pinkish-gray, nonswelling ...... .1

7. Shale, dark-grayish-brown; weathers

hackly ........................................................ 6.0

6. Marlstone, light-gray; persistent marker .2 

5. Shale, dark-gray to black, buttress-weathering ; contains some calcareous streaks 

in upper part ............................................ 9.7

4. Bentonite, pale-yellowish-gray, nonswelling .............................................................. .02

3. Shale; weathers bluish gray and papery; 

upper part harder and contains thin 

calcareous shale layers ............................ 3.1

2. Bentonite, yellowish-gray, nonswelling .... .05

Total lower unit of Sharon Springs

Member measured (rounded) ........ 55.85

Niobrara Formation (part) :

Smoky Hill Chalk Member (part) :

1. Marlstone; weathers bluish gray; abundant limonite and gypsum; a few scattered bones ................................................ 1 +

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46 THE SHARON SPRINGS MEMBER OF THE PIERRE SHALE IN WESTERN KANSAS

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INDEX

A Page 

Abstract ....... ................................................. 1

Age, Niobrara Formation .............................. 6

Sharon Springs Member ........................ 1

Aluminum ............................................ 25, 31, 35, 37

alumina octahedron .................................. 24

Analyses, atomic-absorption ........................ 29, 37

beta-gamma sealer .................................... 27

carbon ...................................................... 26, 28

chemical ...................................................... 22

gasometric .................................................. 26

induction-furnace .................................... 26

mineralogical. See Analyses, X-ray

diffraction, 

six-step spectographic ............ 22, 26, 28, 37

visual detection limits .................. 31, 34

X-ray diffraction ................ 22, 25, 27, 29, 30

volumetric .................................................. 15

Arickaree shales ................................................ 10

Arikaree River .................................................. 10

B

Barium ................................................................ 35

Barren zone ...................................................... 7

Beecher Island Member ............................ 1, 5, 10

Benton Group. See Fort Benton Group. 

Bentonites ............................ 1, 5, 11, 13, 14, 22, 24

aluminous characteristics ...................... 25

analyses .................................................... 22, 30

Weskan Member ...................................... 7

X-ray analyses .......................................... 22

Biogenic sediments .......................................... 5

Black Hills, S. Dak ........................................ 7, 11

Black Hills uplift ............................................ 20

Book Cliffs, Colo .............................................. 7

Boron .......................................................... 34, 35, 37

Burris Draw .............................................. 11, 14, 39

Calcium ...................................................... 25, 35, 37

Calcium carbonate .......................................... 15

Carbon .............................................................. 26, 31

Carbonate, accumulation .............................. 5

calculation .................................................. 22

deposition .................................................. 5

Carlile Shale, Fairport Chalk Member ...... 5

Chattanooga Shale .......................................... 27

Chemical concentrations, geometric

means .......................................... 31

Chemical elements, correlation

coefficients ........................ 31, 34, 37

distribution ................................................ 32

occurrence .......................................... 31, 33, 34

relation to grain size .............................. 38

relation to organic matter .................... 38

See also individual elements. 

Chromium .......................................................... 35

Claggett Shale .................................................. 6

Clay ................................................................... 35, 37

illite .............................................................. 23

kaolinite .............................................. 23, 24, 37

mixed-layer ................................................ 23

montmorillonite ................................ 23, 24, 30

Cobalt ................................................................ 36, 37

[Italic page numbers indicate major references]

Page 

Concretions ...................................................... 11, 23

calcite .......................................................... 31

cone-in-cone ............................................ 10, 12

fossiliferous ................................................ 5

fractured .................................................... 12

iron .............................................................. 4

ironstone .................................................... 7, 10

ledge-forming .......................................... 10, 12

limestone .......................... 7, 10, 12, 18, 22, 31

marl ............................................................ 10

phosphate .................................................. 4

septarian .................................................... 5, 12

septarian limestone ................................ 1, 3

Cope, E. D., quoted ........................................ 3

Copper .............................................................. 35, 38

Correlation coefficients .......................... 31, 34, 37

Crow Creek Member ........................................ 9

D

Dakota Group .................................................... 3

Dark soft shale unit ................................11, 26, 39

DeGrey Member ................................................ 9

Devils Halfacre ........................................ 12, 16, 18

Dolomite .............................................. 15, 23, 35, 37

E

Eagle Sandstone .............................................. 6

Eagle Tail Creek .............................................. 4

Elias, M. K., quoted ........................................ 11

Environment of deposition ............................ 6

Epicontinental sea .......................................... 5

Equivalent uranium. See Uranium.

Facies changes .................................................. 1

Fairport Chalk Member, Carlile Shale ...... 5

Fort Benton Group ........................................ 3, 4

Fort Hays-Fort Wallace area ...................... 3

Fort Hays Limestone Member .................... 6

Fort Pierre Group .......................................... 3, 4

Fort Pierre Shales .......................................... 4

Fort Wallace area ............................................ 3

Fossils, ammonites ................................ 4, 9, 16, 29

Baculites .............................................. 4, 11, 16

anceps .................................................. 4

asperiformis .................... 5, 13, 16 ; pi. 2

clinolobatus ........................................ 10

eliasi .................................................... 10

gilberti ................................................ 16

grandis ................................................ 10

gregoryensis ...................................... 9

jenseni ................................................ 10

mclearni ............................................ 13, 16

obtusus ...................... 11, 14, 16, 18 ; pi. 1

perplexus ............................................ 16

reesidei ................................................ 10

cephalopods ................................................ 5

Cimolichthys nepaholica ........................ 4

Clidastes ...................................................... 4

westii .................................................. 4

Didymoceras cheyennense ...................... 9

Discoscaphites .......................................... 10

Elasmosaurus platyurus ........................ 3

Fossils Continued

Empo Ksbonensis ......................................

Enchodus ....................................................

fish .......................................................... 4

Hoploscaphites ..........................................

inocerams ..................................................

Inoceramus barabini ...............................

cycloides .............................................

subcompressus .................................

vanuxemi ............................................

limpets ........................................................

mollusks ......................................................

mosasaur ....................................................

Pachyrhizodus ..........................................

minimus ..............................................

pelecypods .................................................

Phasganodus ..............................................

carinatus ............................................

Physoelyst .................................................

Physostomus ..............................................

Placenticeras meeki ...............................

plesiosaur ....................................................

Plesiosaurus gulo ......................................

Protosphyraena gigas ............................

Tenuipteria fibrosa ..................................

Toxochelys latiremis .............................

Trachyscaphites spiniger porchi .... 5

Fox Hill beds ....................................................

Fox Hills Sandstone ........................................

Fractures, in concretions ..............................

Frost, I. C., analyst ........................................

Page 

4 

4

,5,11

10

9

4

pi. 2 

pi. 1 

9 

4 

4 

4

4

5

9

4

4

4

4

4

4

10

4

pi. 2 

3

1,10 

12 

26

G

Gallium ............................................................ 35, 37

Goose Creek ...................................................... 10

Grain size .......................................................... 38

Graneros Shale .................................................. 5

Mowry shale .............................................. 15

Greenhorn Limestone ...................................... 5

Gregory Member .............................................. 9

Ground-water resources .................................. 5

Guy Holland test hole .................................... 22,

25, 26, 28, 30, 32, 33, 34, 36, 43

H, I

Hamilton, J. C., analyst ................................ 26

Historical geology ............................................ 5, 18

Iron ........................................................ 4, 24, 35, 37

Lake Creek ........................................................ 10

Lake Creek Member .............................. 1, 5, 9, 24

Lanthanum ................................................ 31, 35, 37

Larimer Sandstone Member .......................... 10

Leaching ............................................................ 37

Lead ............................................................ 34, 35, 37

Lee, Lorraine, analyst .................................... 27

Limestone, cone-in-cone .............................. 12, 18

lenses .......................................................... 9

tepee butte ................................................ 9, 10

See also Concretions. 

Lipp, H. H., analyst ...................................... 27

Lisbon shales .................................................... 4

49
50 INDEX

Page 

Lithium treatment .................................. 23, 25, 30

Logs. See Well logs.

Lower Sharon Springs member .................. 11

M

McAllaster ........................................................ 4, 12

test hole ...................................................... 2

McAllaster Buttes ........................ 7, 12, 18, 21, 24

measured sections .................................... 40

sample log .................................................. 41

Magnesium ................................................ 25, 35, 37

Mancos Shale .................................................... 7

Manganese ...................................................... 35, 37

Measured sections ............................................ 39

Burris Draw .............................................. 39

Devils Halfacre ........................................ 43

locality 1 .................................................... 39

locality 2 ................................................ 40

locality 3 .................................................... 41

locality 4 .................................................... 41

locality 5 .................................................... 42

locality 6 .................................................... 42

location ........................................................ 2

McAllaster Buttes .................................... 40

Prairie Dog Creek .................................. 44

Sharon Springs Member, lower unit .. 39,

41, 42, 44 

upper unit .......................................... 42

Smoky Hill Chalk Member,

upper part ........................ 39, 41, 42

Weskan Member, lower unit ................ 42

Mensik, J. D., analyst .................................... 28

Middle Park, Colo. .......................................... 7

Mineralogical data ............................................ 23

Minerals, adularia ............................................ 30

anatase ...................................................... 35, 38

apatite ...................................................... 30, 35

barite .................................................... 3, 12, 30

basaluminite .............................................. 26

beidellite ...................................................... 25

calcite ................................ 3, 12, 15, 23, 31, 35

chlorite ........................................................ 23

feldspar ....................................... ............ 23

potassium .......................................... 30

gypsum ........................ 3, 12, 15, 18, 23, 26, 30

hydrobasaluminite .................................... 26

illite ............................................................ 23

ilmenite .................................................... 35, 38

jarosite ........................................ 12, 23, 35, 37

kaolinite .............................................. 23, 24, 37

limonite ........................................ 10, 12, 15, 26

monazite .................................................. 35, 39

montmorillonite ................................ 23, 24, 30

pyrite .............................. 12, 23, 27, 31, 35, 37

quartz .......................................................... 23

selenite ........................................................ 3

silicate ........................................................ 27

strontianite ................................................ 36

zircon ........................................................ 35, 38

Missouri River .................................................. 7

Molybdenum .................................................... 36, 38

Mountjoy, Wayne, analyst ............................ 27

N

Nickel ................................................................ 36, 37

Niobium ............................................................ 34, 37

Page

Niobrara Division ..................................- 3, 4

Niobrara Formation ............................ 1, 6, 32, 34

measured section ............................ 39, 41, 42

See also Smoky Hill Chalk Member.

O

Ogallala Formation .......................................... 24

Organic carbon ........................................ ...- 12

Organic matter .......................................... 31, 38

calculation .................................................. 22

Niobrara Formation ................................ 23

organic-rich shale unit .......................... 12

relation to Baculites obtusus ................ 11

relation to molybdenum ............. ...... . 36

relation to trace and minor elements 38 

relation to vanadium .............................. 38

Sharon Springs Member ........................ 23

Organic-rich shale unit ........................ 11, 26, 39

Paleogeography ................................................ 18

Phosphate ............................ 4, 7, 14, 15, 19, 22, 35

Phosphatic shale unit ...................... 11, 14, 26, 39

Potassium .................................................. 25, 35, 37

Prairie Dog Creek .......................................... 3, 17

measured sections .................................... 44

Pueblo, Colo .................................................... 9, 20

R

Radioactivity .......................................... 1, 5, 14, 21

See also Uranium. 

Red Bird, Wyo ................................................ 20

References cited ................................................ 45

Rocky Ridge Sandstone Member ................ 10

Round Butte, Colo .......................................... 20

Salt Grass Canyon .......................................... 10

Salt Grass Member .............................. 1, 5, 10, 24

Sample log, Guy Holland .............................. 43

locality 2 .................................................... 41

locality 6 .................................................... 43

McAllaster Buttes .................................... 41

Scandium ............................................................ 35

Sediment source ........................... ................ 5

Sedimentation, rate ...................................... 16, 28

rate, dark soft shale unit ...................... 17

organic-rich shale unit .................. 17

phosphatic shale unit ...................... 17

Pierre Shale ...................................... 20

Selenium ...................................................... ... 21

Sharon Springs, town .................................... 1, 10

Shipley, G. D., analyst .................................. 15

Silicon .................................................. 27, 31, 35, 37

silica tetrahedron ....................... .. . 24

Silver ........................................................ 31, 37

Smoky Hill Chalk Member ...................... 4, 6, 26

McAllaster test hole ................................ 2

measured section ...................................... 39

upper part ...................................... 41, 42

Smoky Hill River ..........................-.. ........ 2, 5

Sodium ........................................................ 25, 35, 37

Stratigraphic sections. See Measured sections. 

Strontium .................................................. 35, 36, 37

Page 

Sulfur .................................................................. 24

Surface samples .............................................. 37

Telegraph Creek Formation .......................... 6

Tepee butte limestone..................................... 9, 10

Tepee zone .......................................................... 9

Terry Sandstone Member .............................. 9

Test hole, Guy Holland .................................. 22,

25, 26, 28, 30, 32, 33, 34, 36, 43

Guy Holland, sample log ........................ 43

McAllaster .................................................. 2, 41

sample log .......................................... 41

Thickness, Beecher Island Member ............ 10

Fort Hays Limestone Member .............. 6

Lake Creek Member ................................ 9

Niobrara Formation ................................ 6

organic-rich shale unit .......................... 11

phosphatic shale unit .............................. 14

Pierre Shale .............................................. 1, 28

relation to composition .......................... 25

Salt Grass Member .................................. 10

Sharon Springs Member .................. 2, 7, 20

Smoky Hill Chalk Member .................. 6

unnamed member .................................... 10

Weskan Member ...................................... 7

See also Measured sections.

Thomas, J. A., analyst .................................. 28

Titanium .................................................... 31, 35, 38

Trash zones ...................................................... 26

Turner, Theophilus H., fossil collector ...... 3

Twin Butte Creek ............................................ 2

Type locality, Sharon Springs Member .... 7, 10

Weskan Member ...................................... 7

U, V

Unnamed member ........................................ 1, 5,10

Upper Sharon Springs member ................ 11, 15

Uranium .......................................... 5, 21, 31, 36, 38

analyses ...................................................... 26

organic-rich shale unit .......................... 21

See also Radioactivity. 

Vanadium ........................................................ 35, 38

Verendrye Member .......................................... 10

Volumetric analysis ........................................ 15

W

Weathering, bentonites .................................. 25

dark soft shale unit ................................ 11

organic-rich unit ...................................... 12

outcrop samples ........................................ 23

Well logs ............................................................ 39

electric ...........................-... .. ................ 2

gamma ray ......... ................. ................. 2

subsurface correlation .......................... 14, 20

to determine contacts .............................. 7

Weskan Member .............................. 1, 5, 7, 24, 28

measured sections .................................... 42

Y, Z

Ytterbium ........................................................ 35, 37

Yttrium ............................................................ 35, 37

Zinc .................................................................... 34, 37

Zirconium .................................................. 31, 35, 37

U. S. GOVERNMENT PRINTING OFFICE : 1972 O - 459-596
PLATES 1, 2
PLATE 1

[All figures natural size except as otherwise indicated]

FIGURES 1-3. Baculites obtusus Meek (early form) (p. 11).

From orange-weathering limestone concretions 71 feet above base of 

Sharon Springs Member of Pierre Shale at USGS Mesozoic loc. 

D1827 (text fig. 1, loc. 1).

1. Lateral view of a large adult, X %, hypotype USNM 157858. 

2, 3. Lateral views of latex casts of a young adult and a juvenile,

hypotypes USNM 157859, 157860. 

4, 5. Baculites obtusus Meek (late form) (p. 11).

From lower unit of Sharon Springs Member at USGS Mesozoic loc. 

D2663 in the NE% sec. 18, T. 12 S., R. 36 W., Logan County, Kans. 

4, 5. Lateral views of latex casts of specimens that show the 

strong ribbing characteristic of this form of the species. 

Hypotypes USNM 157861, 157862. 

6, 7. Inoceramus cf. /. subcompressus Meek and Hayden (p. 39).

Incomplete specimens from the same locality as figs. 1-3. Figured 

specimens USNM 157872, 157873.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 728 PLATE 1

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MOLLUSKS FROM THE BACULITES OBTUSUS ZONE
PLATE 2

[All figures natural size]

FIGURES 1-11. Baculites asperiformis Meek (p. 5).

From a limestone concretion about 65 feet below top of Sharon Springs Member 

of Pierre Shale at USGS Mesozoic loc. D2591 (text fig. 1, loc. 2).

1, 2. Lateral and ventral views of a juvenile showing rise of flank nodes.

Hypotype USNM 157863. 

3, 4. Lateral and ventral views of a larger juvenile showing rather closely

spaced nodes. Hypotype USNM 157864. 

5, 6. Lateral and ventral views of a young adult showing well-developed

widely spaced nodes. Hypotype USNM 157865. 

7. Lateral view of a young adult with riblike nodes. Hypotype USNM

157866.

8, 9. Lateral and ventral views of a young adult showing most of the living 

chamber which contains a juvenile. Hypotype USNM 157867.

10. Lateral view of the aperture of an adult. Hypotype USNM 157868.

11. Lateral view of part of an adult living chamber showing reduction in 

lateral ornament toward the flared aperture. Hypotype USNM 157869.

12. Trachyscaphites spiniger (Schliiter) subsp. porchi (Adkins) (p. 5).

Lateral view of a fragment of a phragmocone from the same locality as figs. 

1-11 showing the dense ribbing and several rows of tubercles. Hypotype USNM 

157870.

13. Inoceramus aff. /. cycloides Wegner (p. 39).

Fragment showing rather even concentric folds with growth lines from a very 

thin gypsiferous limonite bed 71 feet above base of Sharon Springs Member at 

USGS Mesozoic loc. D2691 (text fig. 1, loc. 1). Figured specimen USNM 157871.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 728 PLATE 2

H

MOLLUSKS FROM THE BACULITES ASPERIFORMIS ZONE