Sedimentary Petrology and Paleocurrents 

of the Harebell Formation, 

Pinyon Conglomerate, and 

Associated Coarse Clastic Deposits, 

Northwestern Wyoming

GEOLOGICAL SURVEY PROFESSIONAL PAPER 734-B
Sedimentary Petrology and Paleocurrents 

of the Harebell Formation, 

Pinyon Conglomerate, and 

Associated Coarse Clastic Deposits, 

Northwestern Wyoming

By DAVID A. LINDSEY

GEOLOGY OF GOLD-BEARING CONGLOMERATES IN 

NORTHWESTERN WYOMING

GEOLOGICAL SURVEY PROFESSIONAL PAPER 734-B

A detailed study of the petrography and sedimentary 

structures of Upper Cretaceous and Paleocene 

gold-bearing conglomerates in northwestern 

Wyoming and adjacent 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. 72-600277

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

Washington, D.C. 20402 - Price $1.50 (paper cover)

Stock Number 2401-00249
CONTENTS

Page

Abstract................................................................................... Bl

Introduction............................................................................... 3

Purpose of study............................................................. 3

Geologic and geographic setting................................... 3

Methods of study.............................................................. 4

Acknowledgments............................................................. 4

Stratigraphy.............................................................................. 4

Cretaceous and Tertiary section.................................. 4

Harebell Formation......................................................... 5

Pinyon Conglomerate...................................................... 5

Regional lithofacies......................................................... 8

Quartzite-bearing conglomerates of other ages......... 8

Lithology and petrography..................................................... 8

Conglomerate .................................................................. 8

General description.................................................. 8

Size, shape, and surface markings of roundstones...................................................................... 9

Lithology of roundstones....................................... 10

Petrography of roundstones.................................. 12

Petrography of matrix........................................... 22

Sandstone........................................................................... 24

General description.................................................. 24

Petrography............................................................... 25

Minor lithologies............................................................... 27

	Page 

Sedimentary structures and paleocurrents......................... B29

Imbrication......................................................................... 29

Description................................................................. 29

Measurement and statistical analysis.................. 29

Comparison of imbrication in conglomerates

with that in modern streams............................. 32

Paleocurrents............................................................ 35

Crossbedding and ripple cross-lamination................... 35

Harebell and Pinyon paleocurrents..................... 35

Upper Cretaceous and Paleocene paleocurrents compared...................................................... 38

Regional variation of quartzite roundstone size....... 40

Synthesis of information on sediment dispersal......... 43

Other quartzite-bearing conglomerates............................... 48

Beaverhead Formation................................................... 48

Fort Union Formation..................................................... 50

Conclusions................................... .......................................... 56

Source of conglomerates................................................. 56

Evidence for long-distance transport... --...-...... 56

Objections to long-distance transport........... . 62

Alternative explanations.- . .. --. ............... 63

Depositional environment ............................................ 64

References cited. .... ......................................................... 65

ILLUSTRATIONS

Page

FIGURE 1. Map showing the geographic and geologic setting of Upper Cretaceous and Paleocene quartzite-bearing

conglomerates in northwestern Wyoming and adjacent areas............................................... ... -....... - B2

2. Map showing distribution of the Harebell Formation and the Pinyon Conglomerate and station localities

where samples used in this study were measured or collected..........-.-----........-- ............... .... ................. 7

3-5. Photographs showing:

3. Quartzite roundstone conglomerate in the Pinyon Conglomerate along the South Fork of Fish

Creek............................................................................................................. ....... .. 9

4. Typical conglomerate containing well-rounded moderately sorted quartzite roundstones in hard

sandstone matrix, Harebell Formation north of Blackrock Creek....................................................... 10

5. Typical shapes and rounding of quartzite roundstones from conglomerate of the Harebell Formation, Whetstone Mountain...................................................................---...... .. 10

6. Photograph and photomicrograph of large quartzite boulder in Pinyon Conglomerate north of the Teton

Range.........................................................................................................................................-.............-........-...---.- . 11

7. Zingg plots of quartzite roundstone dimensions at three stations 11

8. Photographs showing crescentic percussion marks and pressure marks on quartzite roundstones..................... 12

9. Map showing classification of the conglomerates of the Harebell Formation and the Pinyon Conglomerate

into three lithofacies according to proportions of minor roundstone types present 14

10. Histograms showing frequency distributions of quartzite, soft sedimentary rock, and volcanic roundstones

in the northern and southern conglomerate facies......... ................................................. . 15

11. Diagrams showing summary of color, texture, and feldspar content of quartzite roundstones.. ............. . 16

12-15. Photomicrographs of:

12. The principal types of texture and mineralogy exhibited by the quartzite roundstones . 17

13. Sedimentary and plutonic roundstones......--.....-.........................--..........-----.-.. 19

14. Typical volcanic roundstones.............. ..................... ..................................... ................. ........ 20

15. Matrix of conglomerates........ -.-......-....... ...-..-..-... .. ..... ............... .......... . .. - 24

in
IV CONTENTS

Page

FIGURE 16. Triangular diagrams showing classification of sandstone matrix of conglomerates. .......................................... B24

17. Photomicrographs of sandstones and tuffaceous rocks...............--..---......................----------.............---.---.---------......... 26

18. Triangular diagram showing composition of clastic constituents and map showing distribution of tuffaceous and nontuffaceous sandstones in the lower member of the Harebell Formation............................ 26

19. Photograph showing imbrication in the Pinyon Conglomerate along the South Fork of Fish Creek... ......... 28

20. Lower hemisphere stereographic projection of 50 c-axis orientations of oblate roundstones............................ 29

21. Diagrams showing frequency distributions of the vector magnitudes and of the radii of the spherical

circles of confidence for c-axis orientations in the Harebell Formation and the Pinyon Conglomerate.... 32

22. Photograph showing imbrication of quartzite roundstones derived from the Pinyon Conglomerate on the

North Fork of Fish Creek........................................................................................................................................... 33

23. Histograms showing comparison of mean angle of inclination and dispersion of c-axis orientations between 

roundstones from the Harebell Formation and the Pinyon Conglomerate and roundstones from modern streams in Jackson Hole.--....-.....-..-......... . ................................................................................................. 34

24. Map showing paleocurrent directions as interpreted from imbrication azimuths in the Harebell Formation

and the Pinyon Conglomerate.................. ............................................................................................................... 36

25. Map showing moving-average directions based on imbrication in the Harebell Formation and the Pinyon

Conglomerate-...--.................-........-....-.--..-..-..........----..---------..........---------.---...---------------.-.-.--.--.--... 37

26. Photograph showing large-scale festoon crossbedding in sandstone lenses near the top of the Pinyon Conglomerate on Purdy Creek.......................................................................................................................................... 38

27. Map showing crossbedding orientation in the Harebell Formation and the Pinyon Conglomerate.................... 39

28. Rose diagrams showing paleocurrent directions as interpreted from crossbedding orientations in Upper

Cretaceous and Paleocene rocks between the Gros Ventre River and Buffalo Fork.................................... 40

29. Histograms of frequency distributions of mean maximum quartzite roundstone lengths for stations in the

northern and southern conglomerate facies.................. ...................................... ........... .......... ..... . ... 43

30-34. Maps showing:

30. Moving-average isopleths of mean maximum quartzite roundstone lengths at stations in the

Harebell Formation and the Pinyon Conglomerate.............................................................................. 44

31. Moving-average isopleths of maximum quartzite roundstone lengths at stations in the Harebell

Formation and the Pinyon Conglomerate.............................................................................................. 45

32. Highest-degree significant surfaces fitted to mean maximum quartzite roundstone length at stations in the Harebell Formation and the Pinyon Conglomerate...................................................... 46

33. Interpreted positions and orientations of major paleostreams responsible for deposition of the

Harebell Formation and the Pinyon Conglomerate. ........................................................................ 47

34. Station localities, imbrication azimuths, and mean maximum quartzite roundstone lengths in the

Divide quartzite conglomerate lithesome of the Beaverhead Formation.......................................... 49

35. Photograph of typical outcrop of the Divide quartzite conglomerate lithosome of the Beaverhead Formation above the West Fork of Indian Creek.. .................................................................................................... 50

36. Photograph of large quartzite roundstones in the Divide quartzite conglomerate lithosome of the Beaverhead Formation above Edie Creek........................................................................................................................... 51

37. Pie diagrams showing petrographic affinities of five quartzite-bearing conglomerate facies studied by the

author---.....-.---.---...--.............................................----.--........-.-.--.-..---........-.-..-.....-....-.-------.....-.. 52

38. Map showing station localities, crossbedding orientations, and quartzite roundstone lengths in the Lance

and Fort Union Formations on the west flank of the Bighorn Basin.....-------.... ..................................... 53

39-41. Photographs of:

39. Section of conglomerate in Fort Union Formation north of Cody............................................................ 54

40. Quartzite pebble and cobble conglomerate in the Fort Union Formation . . . .. 55

41. Typical quartzite roundstones from conglomerate in the Fort Union Formation------.-- . -- . 56

42. Photomicrographs of typical textures and mineralogy of quartzite roundstones found in the Fort Union

Formation........................................................................................................................................................................ 56

43. Map showing integration of petrographic and paleocurrent evidence into the geologic setting of the

quartzite-bearing conglomerates................................................................................................................................. 58

44. Maps showing suggested interpretation, according to the long-distance-transport hypothesis, of the sources,

dispersal routes, and depositional areas of the quartzite-bearing conglomerates.- .................................... 60

45. Diagrams showing velocities and depths of streams necessary to transport roundstones found in the Harebell Formation and the Pinyon Conglomerate----.-.- 63

TABLES

TABLE 1. Quaternary, Tertiary, and Cretaceous stratigraphic section of Jackson Hole, Wyo.................. .. .............

2. Composition of roundstones counted in the western facies, the northern facies, and the southern facies.

Page

B5

13
CONTENTS V

Page 

TABLE 3. Student's t tests for significant differences in roundstone lithology between the northern and southern facies and between the Harebell Formation and Pinyon Conglomerate within the northern facies.............. B13

4. Proportions of volcanic rock types among roundstones from the northern and southern conglomerate facies 21

5. Rapid rock analyses of volcanic roundstones from conglomerates of the Harebell Formation and the Pinyon

Conglomerate...........----.-.....------------..-------------.-...-.--..--.-..--...---.-...-......................--.............----...----.......--..........-.----........... 21

6. Modal composition of the sandstone matrix of conglomerates of the northern facies and the southern facies 23

7. Nonopaque heavy minerals in the sandstone matrix of conglomerates in the western facies, the northern facies, and the southern facies.................. .................................................................................................................. 25

8. Modal composition of the tuffaceous and nontuffaceous sandstones of the lower member of the Harebell

Formation. .................................................................................................................................................................... 25

9. Rapid rock analyses of nontuffaceous and tuffaceous sandstones from the lower member of the Harebell

Formation... ... .... .. ...................................................................................................................................... 27

10. Nonopaque heavy minerals in sandstones of the Harebell Formation.......... ........................................................... 29

11. Imbrication statistics at stations in the western facies, the northern facies, and the southern facies............. 30

12. Imbrication statistics for 24 determinations of 50 c-axis orientations each in modern streams of Jackson

Hole............................................................................................................................................................................. 32

13. Analysis of variance and estimates of variance components for imbrication azimuths-.................................. 35

14. Length of largest quartzite roundstones at stations in the western facies, the northern facies, and the

southern facies.....................-...........................-....................-.............................................. ......................................... 41

15. Student's t tests for significant differences in mean maximum roundstone length between the northern and 

southern facies and between the Harebell Formation and the Pinyon Conglomerate within the northern facies........- ............................................................................................................................................................. 42

16. Analysis of variance and estimates of variance components for measurements of mean maximum quartzite

roundstone length...-.........-...-...-.............................................. ................................................................................... 42

17. Percent reduction of the sum of squares for trend surfaces fitted to mean maximum quartzite roundstone

length in the northern and southern conglomerate facies.......................... ....................................................... 48

18. Analysis of variance of data from trend surfaces fitted to mean maximum quartzite roundstone length in

the northern and southern conglomerate facies---..-......... ..................................................................................... 48

19. Composition of roundstones counted in the Divide quartzite conglomerate lithesome of the Beaverhead

Formation and in the Lance and Fort Union Formations..-...................................-................................. .......... 48

20. Imbrication statistics for 17 determinations of 50 c-axis orientations each in the Divide quartzite conglomerate lithesome of the Beaverhead Formation....-- ............................................................................................ 51

21. Nonopaque heavy minerals in the Lance and Fort Union Formations, western flank of the Bighorn Basin.. 54

22. Mann-Whitney [/-tests for differences between means of Upper Cretaceous and Paleocene heavy mineral

suites from Jackson Hole and those from the Bighorn Basin............................................................................ 55
GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

SEDIMENTARY PETROLOGY AND PALEOCURRENTS OF THE HAREBELL

FORMATION, PINYON CONGLOMERATE, AND ASSOCIATED COARSE

CLASTIC DEPOSITS, NORTHWESTERN WYOMING

By DAVID A. LINDSEY

ABSTRACT

The quartzite roundstone conglomerates of the Harebell 

Formation and the Pinyon Conglomerate in Jackson Hole are 

part of a series of Upper Cretaceous and lower Tertiary 

coarse clastic deposits that crop out discontinuously from the 

Centennial Range in Idaho to the Green River and Bighorn 

Basins in northwestern Wyoming. Inasmuch as most of these 

conglomerates contain small quantities of fine-grained gold of 

supposed detrital origin, a petrographic and paleocurrent 

study was undertaken to determine the source of the conglomerates.

The Harebell Formation (Upper Cretaceous) and the 

Pinyon Conglomerate (Upper Cretaceous and Paleocene) can 

be divided into four lithofacies: a lower, sandstone lithofacies 

and three quartzite roundstone conglomerate lithofacies. The 

sandstone facies underlies and perhaps intertongues with 

two of the conglomerate facies; it contains some highly 

tuffaceous sandstones as well as nontuffaceous sandstones 

and minor amounts of conglomerate, shale, and coal. The 

conglomerate facies are divisible into (1) the western facies, 

located at the north end of the Teton Range and characterized by abundant roundstones of quartzite and soft sedimentary rocks; (2) the northern facies, located north of Spread 

Creek in Jackson Hole and characterized by abundant quartzite, few soft sedimentary rocks, few volcanic rocks, and 

almost no welded-tuff roundstones; and (3) the southern 

facies, located between Spread Creek and the Gros Ventre 

River, which contains abundant quartzite and also more volcanic and welded-tuff roundstones than the northern facies. 

Commonly, only a few thin lenses of sandstone and shale 

are found in the conglomerates.

Paleocurrent directions in the Harebell Formation and the 

Pinyon Conglomerate were determined by measuring crossbedding orientation in the sandstone facies and both imbrication and crossbedding orientation in the conglomerate facies. 

Paleocurrents that deposited the western conglomerate facies flowed southeasterly; those /that deposited the sandstone 

facies and the overlying northern conglomerate facies, eastnortheasterly; and those that deposited the southern conglomerate facies, south-southeasterly. Maximum and mean 

maximum quartzite roundstone sizes show a downstream 

decrease. Regions of maximum roundstone size may define

the courses of major paleostreams: two in the northern facies 

and as many as three in the southern facies.

Quartzite-bearing conglomerates in part of the Beaverhead 

Formation of southwestern Montana and adjacent Idaho and 

in the Fort Union Formation of the Bighorn Basin were 

studied to assess their possible relation to the Harebell and 

Pinyon. The Divide conglomerate lithesome (Ryder, 1967) 

of the Beaverhead Formation contains quartzite, soft sedimentary rock, and volcanic roundstones that are petrographically identical with those of the Harebell and Pinyon and 

suggest a similar source terrane. Imbrication and variation 

in quartzite roundstone size suggest derivation from the 

southwest. In contrast, the Fort Union conglomerates near 

Heart Mountain contain quartzite roundstones and heavymineral species that suggest a source terrane different from 

that of the Harebell and Pinyon. Crossbedding orientations 

indicate a source to the southwest, perhaps the Paleozoic 

terrane of the Late Cretaceous-Paleocene Washakie Range 

uplift.

Although alternative explanations cannot be entirely ruled 

out, I favor long-distance transport of coarse detritus from 

western and northwestern sources in Idaho and Montana to 

explain the present composition and distribution of conglomerates in the Harebell and Pinyon. Much of the quartzite 

probably came from the present region of Precambrian 

quartzites of the Belt Supergroup in Idaho and Montana and 

Precambrian and Cambrian quartzites in southeastern Idaho; 

Paleozoic orthoquartzites and quartzose sandstones from a 

wide area to the west and northwest may also have contributed significantly. Many of the volcanic roundstones in 

the Harebell and Pinyon can be explained by derivation from 

similar rocks in the Upper Cretaceous Elkhorn Mountains 

Volcanics and Livingston Group to the north. Paleozoic and 

Mesozoic sedimentary rocks to the west and northwest supplied soft sedimentary roundstones to the conglomerates.

Plant and vertebrate fossils and sedimentary features 

suggest a warm, humid terrestrial environment of deposition 

for the conglomerates, but microfossils and a few invertebrate 

fossils suggest the proximity of marine conditions in Late 

Cretaceous time. The conglomerates probably accumulated as 

alluvial fans next to rapidly rising highlands to the west and 

north of Jackson Hole.

Bl

479-609 O - 72 - 2
B2 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

114° 113 111'

pper Cretaceous

Elkhorn Mountains

Volcanics

Upper Cretaceous 

Livingston Group

Southeastern limit of

Precambrian quartzites

of Belt Supergroup

(Ross, 1963, pl.l)

EXPLANATION

V \

X

^Paleocene and Upper Cretaceous 

Divide quartzite conglomerate 

lithesome (Ryder, 1967) of the 

Beaverhead Formation

YELLOWSTONE 

NATIONAL PARK

Paleocene and Upper 

iCretaceous Pinyon -.-., 

(Conglomerate and c~ 

Upper Cretaceous 

Harebell Formation

v>

\*

^\ \'c

\

Paleocene and Upper Cretaceous

quartzite-bearing conglomerates

Upper Cretaceous volcanic fields

Contact

Normal fault 

Hachures on downthrown side

Thrust fault 

Sawteeth on upper plate

\\ -\\.

x\

' ^

J^"

Pinyon Conglomerate-15 | 

I

Precambrian gneissic rocks 

Overlain mostly by Paleozoic rocks

Eastern limit of thick Precambrian and 

Cambrian quartzite sequence

(Crittenden and others, 1971)

Precambrian Belt Supergroup

Partly quartzite

BlackfootH

\

\

\

TKc

FIGURE 1. Geographic and geologic setting of Upper Cretaceous and Paleocene quartzite-bearing conglomerates
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B3

Mountain and Upper Cretaceou 

Lance Formations

in northwestern Wyoming and adjacent areas.

INTRODUCTION

PURPOSE OF STUDY

This is the second in a series of reports on the 

gold-bearing conglomerates of northwestern Wyoming, designated the Harebell Formation (Upper 

Cretaceous) and the Pinyon Conglomerate (Upper 

Cretaceous and Paleocene). The first report in the 

series, by Love (1972), covered the stratigraphy of 

the conglomerates. The conglomerates are characterized by a very large volume of quartzite boulders, 

cobbles, and pebbles and by small quantities of finegrained detrital gold (Antweiler and Love, 1967). 

The absence of abundant quartzite nearby in presentday uplifts suggests that these terranes were not the 

source of either the conglomerates or the gold contained within them. The purpose of the present study 

is to present petrographic and paleocurrent evidence 

bearing on the source or sources of the conglomerates.

GEOLOGIC AND GEOGRAPHIC SETTING

The Harebell Formation and the Pinyon Conglomerate are part of a series of Upper Cretaceous and 

Paleocene coarse clastic deposits which extend discontinuously from southwestern Montana and adjacent Idaho to the Bighorn Basin of Wyoming (fig. 

1). All the deposits shown in figure 1 are distinguished by abundant quartzite boulders, cobbles, and 

pebbles and by at least small amounts of fine-grained 

gold. These deposits consist of the Upper Cretaceous 

to Paleocene quartzite conglomerates in the Beaverhead Formation, the Pinyon Conglomerate at the 

north end of the Teton Range, the Harebell Formation and the Pinyon Conglomerate in Jackson Hole, 

and local conglomerates in the Paleocene Fort Union 

Formation along the west flank of the Bighorn Basin.

Certain regional geologic features which are pertinent to possible sources of the conglomerates, and 

which are also shown in figure 1, are the east margins of the Wyoming overthrust belt (Armstrong 

and Oriel, 1965) and of the southwestern Montana 

overthrust belt (Scholten, 1968) ; the present eastern 

limits of Precambrian quartzites of the Belt Supergroup (Ross, 1963, pi. 1), of Precambrian and Cambrian quartzites (Crittenden and others, 1971), and 

of thick Ordovician orthoquartzites (Ketner, 1966, 

1968) ; the present distribution of Precambrian 

gneissic rocks overlain mostly by Paleozoic rocks 

(taken from State geologic maps by Love and others, 

1955; Ross and Forrester, 1947; and Ross and others, 1955) ; and the present distribution of Upper 

Cretaceous volcanic fields (Ross and others, 1955).

The Harebell Formation and the Pinyon Conglomerate are situated mainly in the highlands between 

the Gros Ventre River and the south boundary of
B4 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

Yellowstone National Park, to the east and northeast 

of the lowest part of Jackson Hole (figs. 1 and 2). 

Jackson Hole itself is a structural and topographic 

basin, about 30-50 miles across, bounded by high 

mountain ranges on three sides. The Teton, Gros 

Ventre, and Wind River Ranges comprise a chain of 

uplifts which expose Precambrian gneissic cores 

mantled by Paleozoic and Mesozoic sedimentary 

rocks; these uplifts form the western and southern 

boundaries of Jackson Hole. With respect to regional 

structure, Jackson Hole and the ranges to the south 

and west are partly fault-bounded large blocks situated on the edge of the stable foreland Rocky Mountains of Wyoming; nearby and to the southwest is 

the overthrust belt of Idaho and western Wyoming 

(Horberg and others, 1949). Tertiary volcanic terranes of the Yellowstone National Park area and the 

Absaroka Range bound Jackson Hole on the north 

and east. Partially exposed beneath the Eocene 

Absaroka Volcanic Supergroup is the Washakie 

Range, a northwest-trending uplift of Paleozoic 

rocks that was beveled by erosion prior to deposition 

of the Absaroka Volcanic Supergroup.

METHODS OF STUDY

The present study deals mainly with the petrography and paleocurrents of the gold-bearing conglomerates. Information on stratigraphy is cited 

from various reports by J. D. Love. Field measurements were made to determine roundstone lengths 

and imbrication and crossbedding orientations. Pebbles and cobbles were identified in field counts and in 

specimens selected for laboratory study, as were 

conglomerate matrix and sandstone. The petrography of specimens was studied by conventional laboratory techniques, including use of thin sections, 

hydrofluoric acid-etched and cobaltinitrite-stained 

rock slices, and bromoform separation of heavy minerals. The data derived from these studies were 

grouped accordng to rock units (formations, lithofacies) and summarized by descriptive statistics; 

statistical tests were applied to answer pertinent 

geologic questions. Some of the groupings involve 

data from rocks of more than one age, and results 

of additional tests are presented to show that stratigraphic variation is not major. Finally, the data are 

summarized in relation to the geologic framework 

of northwestern Wyoming and adjacent parts of 

Montana and Idaho in an attempt to provide a 

clearer understanding of the sources of the conglomerates and the regional geologic events which 

led to their deposition.

Throughout the present study, I followed a uniform procedure of field observation and sampling. 

Under the procedure, the standard field sampling

unit is termed the "station"; all station localities in 

the Harebell Formation and the Pinyon Conglomerate are shown in figure 2; those for the other formations studied are shown in figures accompanying 

later discussions. The station is an outcrop where 

as many types of observations as proved feasible 

were made: measurement of roundstone length, 

measurement of imbrication and crossbedding orientations, counting of identified roundstones, and collection of specimens for laboratory study. Measurements of roundstone length in traverses as much as 

1,000 feet long were grouped under one station; at 

some stations measurements from small adjacent 

outcrops were combined to assure that all stations 

were comparable. The stations were dispersed as 

evenly as possible over much of the area of occurrence of the formations studied in order to achieve 

as representative a sample of the whole as possible, 

but the stations and samples were not selected by 

random methods. Uneven distribution of outcrop, 

inaccessibility of some areas, and uncertain stratigraphic control all hindered the collection of representative measurements and samples. However, I 

believe that the outcrops studied (in some formations, a large part of the total) are for the most part 

geologically representative of the formations studied.

ACKNOWLEDGMENTS

I thank J. C. Antweiler and J. D. Love for introducing me to the geology of Jackson Hole and providing many hours of stimulating discussion and advice. 

Harold Ganow and Steven Rudy assisted me in 

fieldwork. Margaret Roberts and Robert Terrazas 

wrote computer programs and assisted with computer analysis of data. D. A. Seeland provided a 

computer program for rotation and analysis of crossbedding orientations. F. S. Fisher donated samples 

and laboratory notes. W. L. Rohrer, H. J. Prostka, 

W. H. Hays, and S. S. Oriel contributed by discussion; R. H. Tschudy identified pollen samples; E. T. 

Ruppel, W. R. Keefer, and D. E. Trimble loaned rock 

samples for comparative studies; and I. J. Witkind 

identified rock samples and contributed by discussion 

of the geology of southwest Montana. All those 

acknowledged are employed by the U.S. Geological

Survey.

STRATIGRAPHY

CRETACEOUS AND TERTIARY SECTION

Table 1 summarizes the post-Jurassic stratigraphic section of Jackson Hole and vicinity. In 

general, the section is divisible into four parts: 

marine, mixed marine and continental, continental, 

and continental volcanic. Marine sandstones and 

shales dominate the lower part of the section from 

the Lower Cretaceous Cleverly Formation to the
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B5

Upper Cretaceous Bacon Ridge Sandstone. Evidence 

of marine environments persists into the Late Cretaceous Harebell Formation (Love, 1972), but abundant fossil remains and coals indicate recurrent 

continental environments from the deposition of the 

coaly sequence through Harebell time. Continental 

conglomerates, sandstones, and shales were deposited 

from Late Cretaceous and Paleocene Pinyon time 

into Eocene Wind River time. Beginning with the 

Eocene Wind River Formation, a thick succession 

of continental volcaniclastic rocks completes the 

Tertiary section.

TABLE 1. Quaternary, Tertiary, and Cretaceous stratigraphic section of Jackson Hole, Wyo.

[Modified from Love (1956b) ; asterisk(*) indicates supplemental information from Love (1972), Rohrer (1966a, 1968, 1969), Rohrer and Obradovich 

(1969), and Smedes and Prostka (1972) ]

System

Quaternary

Quaternary 

or

Tertiary

Tertiary 

and 

Cretaceous

Series

Pleistocene 

or

Pliocene

Pliocene

Miocene

Eocene

Paleocene

Paleocene 

and 

Upper 

Cretaceous

Upper

Cretaceous

Lower 

Cretaceous

Maximum 

Formation and rock types thickness, 

in feet

Alluvium, alluvial terraces, volcanic 

ash, basalt flows, till, and glacial 

outwash..... . ................. ....................... Variable

Bivouac Formation : conglomerate.

Teewinot Formation : limestone, tuff, 

pumicite, claystone, and conglomerate......................................................... 5,000

Colter Formation : pyroclastic conglomerate, sandstone, and claystone 7,000

*Wiggins Formation : Volcanic conglomerate and tuffaceous claystone.. 2,500 

*Tepee Trail Formation : tuffaceous 

sandstone, mudstone, and claystone.. *1,500 

*Wind River Formation : sandstone, 

tuffaceous sandstone, claystone, 

mudstone, arkosic conglomerate, 

quartzite-bearing conglomerate, and 

coal.......---..------ ------- *1,800

Unnamed sandstone and claystone 

sequence: sandstone, claystone, and 

minor coal. . *1,500

Pinyon Conglomerate : quartzite-cobble and pebble conglomerate with 

minor sandstone, shale, and coal........ *3,000

Harebell Formation : sandstone, shale, 

and quartzite cobble and pebble conMeeteetse Formation : tuff, bentonite,

Mesaverde Formation : sandstone........ 982 

Lenticular sandstone and shale seCoaly sequence : shale, coal, and sandstone- -- 1,000

Bacon Ridge Sandstone: sandstone 

and minor shale, coal, and bentonite 1,250 

Cody Shale : shale and sandstone. 2,200 

Frontier Formation : sandstone, shale, 

porcellanite, and bentonite 1,100

Mowry Shale : shale, bentonite, tuff,

Thermopolis Shale: shale and sandstone . - 300

Cleverly Formation : sandstone. . ?

HAREBELL FORMATION

The Harebell Formation was named by Love 

(1956a) for Harebell Creek, along the southern 

margin of Yellowstone National Park (fig. 2). Parts 

of the Harebell had previously been referred to the 

Laramie Formation (Hague, 1896), the Mesaverde 

Formation (Foster, 1947; Bengston, 1956), the conglomeratic sandstone sequence (Love and others, 

1948), and the Lance Formation (Love and others,

1955). Angular unconformities are reported at the 

base and top of the Harebell Formation (Love, 

1956a, b; 1972).

Love (1971) defined two members in the Harebell: 

an unnamed lower, sandstone member and an upper, 

quartzite roundstone conglomerate member, which 

he named the Bobcat Member. In the type section of 

the Harebell, the lower member contains about 5,000 

feet of sandstone, siltstone, and claystone, with 

lenses of quartzite conglomerate. The Bobcat Member near Bobcat Ridge consists of more than 3,000 

feet of quartzite roundstone conglomerate. North of 

Pacific Creek, the lower member contains abundant 

volcanic detritus and is probably equivalent in part 

to the Landslide Creek Formation (Fraser and others, 1969, p. 34-37) less than 50 miles to the north. 

Along Blackrock Creek, the lower member contains 

about 3,000 feet of sandstone, siltstone, and claystone. Here the lower member is overlain by about 

1,000 feet of quartzite roundstone conglomerate of 

the Bobcat Member, and this sequence, in turn, is 

overlain by nearly 2,000 feet of sandstone and claystone. To the south, along the Gros Ventre drainage, 

the Harebell is locally present as sandstone, siltstone, 

and shale, with lenses of conglomerate; it ranges in 

thickness from 50 to more than 800 feet. The conglomerate lenses are composed mainly of pebbles 

derived from Paleozoic and Mesozoic rocks, but some 

quartzite pebbles are present.

The age of the Harebell, as determined on the 

basis of fossil evidence (plants, fresh-water invertebrates, fragmentary dinosaur remains, and 

pollen), is Late Cretaceous (Love, 1956a, b; 1972). 

Plant fossils indicate that both the Harebell and the 

Pinyon were deposited in a warm, humid terrestrial 

environment (Love, 1956c, 1972). Possible marine 

microfossils, including acritarchs and dinoflagellates 

and, in the Harebell Formation, Mytilusl clams 

(Love, 1972), suggest the occasional proximity of 

marine waters during Late Cretaceous time.

PINYON CONGLOMERATE

The Pinyon Conglomerate was named by W. H. 

Weed (in Hague, 1896) for exposures on Pinyon 

Peak, a few miles south of Yellowstone National Park

(fig. 2). It overlies the Harebell Formation, and the 

contract in some places is an angular unconformity

(Love, 1956b, 1972). The Pinyon is unconformably 

overlain by Tertiary volcanic rocks on Pinyon Peak

(Hague, 1896) and conformably overlain by an unnamed sandstone and claystone sequence in the area 

from Cottonwood Creek to Park Creek (Love, 1947; 

Rohrer, 1969).

Love (1956b) divided the Pinyon into two members. The lower member consists of 50-140 feet of
B6 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING
Cong. /.nerate facies 

cw, western (Pinyon Conglomerate) cnp, northern (Pinyon Conglomerate) 

cnh, northern (Bobcat Member of Harebell

Formation)

cs, southern (Pinyon Conglomerate) cu, unclassified (Pinyon Conglomerate)

sp- ;'.sh ; : #. 

Sandstone facies

sp, lower member of Pinyon Conglomerate 

sh, lower member of Harebell Formation

Contact 

Dashed where inferred

Station locality

Number corresponds to middle number (as, 

P-25l-tj of thin-section or heavy-mineral 

field number

W377

.W378

W379

Station locality

Number is for sample

collected by others

111 "00' 30'

FIGURE 2. Distribution of the Harebell Formation and the Pinyon Conglomerate and station localities where samples used in this study were measured

or collected.

H3

» 

O f1 O O

o o d

02tti f

dh3 i iO 

OO^02

W
B8 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

coal, sandstone, and claystone. In most places it is 

obscured by covered slopes, but it crops out north of 

Upper Slide Lake and north of Mount Leidy, where 

it is interbedded with the overlying conglomerate. 

The overlying conglomerate member consists almost 

entirely of quartzite roundstone conglomerate with 

only thin lenses of sandstone and shale. The conglomerate member is about 3,000 feet thick at the 

principal reference section (Love, 1972), more than 

1,000 feet thick on Gravel Mountain (Love, 1956b), 

and 1,000 1,500 feet thick in complete measured 

sections on Cottonwood Creek and on the North 

Fork of Fish Creek (Love, 1947). To the southeast, 

on Park Creek, the conglomerate thins to slightly 

more than 200 feet. Remnants of similar conglomerate north of the Teton Range, on Mount Sheridan 

in Yellowstone National Park (Love, 1956c; Love 

and Keefer, 1969), and along the upper Green River 

(Richmond, 1945) have been considered part of the 

Pinyon Conglomerate (fig. 2).

The Pinyon Conglomerate was originally assigned to the Eocene (Hague, 1896), when that 

epoch was considered to be the base of the Tertiary. 

Love (1947, 1956b) considered the Pinyon to be 

Paleocene and cited as evidence the species of fossil 

vertebrates, invertebrates, and plants. Pollen from 

the coal beds in the lower member north of Upper 

Slide Lake confirms a Paleocene age for much of the 

southern part of the Pinyon (Love, 1972). The lower 

150 feet of strata at the principal reference section, 

however, is considered, on the basis of a dinosaur 

tooth found here, to be Late Cretaceous in age (McKenna and Love, 1970).

REGIONAL LITHOFACIESi

During the present study I found that the conglomerates in the Harebell Formation cannot be 

distinguished from those in the Pinyon Conglomerate on the basis of their petrography and paleocurrent directions. Variations in petrography and 

paleocurrent directions were found to be regional 

rather than stratigraphic. Other criteria have been 

used to distinguish between the two formations 

(Love, 1972, table 1). For the present report, however, the two formations are rearranged into lithofacies, and variations between and within the facies 

are emphasized (fig. 2).

The conglomerates are divided, on the basis of 

regional differences in roundstone lithology, into the 

western, northern, and southern conglomerate facies 

(fig. 2). The western facies, north of the Teton 

Range, is regarded as part of the Pinyon Conglomlrthe terms "lithofacies" and "facies" as used here refer only to aspect 

(appearance and composition) and do not imply spatial relationships, such 

as lateral continuity or equivalence (Weller, 1960, p. 503-522).

erate, but its exact age is uncertain. The northern 

facies, north of Spread Creek in Jackson Hole, comprises both the Bobcat Member of the Harebell Formation and the overlying Pinyon Conglomerate. As 

defined, the northern facies ranges in age from Late 

Cretaceous to Paleocene. The southern facies, south 

of Spread Creek and in the Gros Ventre drainage, 

consists entirely of the Paleocene part of the Pinyon 

Conglomerate.

The sandstones of the lower members of both the 

Harebell Formation and the Pinyon Conglomerate 

constitute a fourth lithofacies. Although both Upper 

Cretaceous and Paleocene strata are included, the 

sandstone facies generally underlies and perhaps 

intertongues with the conglomerates. North of 

Blackrock Creek, sandstone of the lower member 

of the Harebell Formation underlies conglomerate 

of the Bobcat Member of the Harebell Formation as 

well as conglomerate of the Pinyon Conglomerate. 

South of Blackrock Creek, sandstones of the Harebell Formation and of the lower member of the 

Pinyon Conglomerate are found locally under the 

upper member of the Pinyon Conglomerate.

QUARTZITE-BEARING CONGLOMERATES OF OTHER AGES

Quartzite roundstones similar to those of the Upper Cretaceous and Paleocene conglomerates dominate conglomerates of the Eocene Pass Peak Conglomerate of Eardley, Horberg, Nelson, and Church 

(1944; Dorr, 1956; Steidtmann, 1969, 1971) and 

the Eocene Wind River Formation (Rohrer, 1968, 

1969). Quartzite roundstones occur also in the 

tuffaceous conglomerates of the Miocene Colter Formation (Love, 1956b) and in numerous Pleistocene 

and Holocene alluvial terraces in and around Jackson Hole.

LITHOLOGY AND PETROGRAPHY 

CONGLOMERATE

GENERAL DESCRIPTION

Quartzite roundstone conglomerate is the most 

distinctive lithology of the Harebell Formation and 

the Pinyon Conglomerate. It occurs in thick beds, 

and more than 1,000 feet is exposed in single outcrops. Stratification is generally crudely defined by 

sandstone lenses and carbonate-cemented ledges (fig. 

3). Commonly only a few thin sandstone and shale 

lenses are present, but thick crossbedded sandstones 

similar to those in the overlying unnamed Paleocene 

sandstone and claystone sequence occur near the top 

of the conglomerate along the South Fork of Fish 

Creek. The conglomerate consists mainly of rounded quartzite pebbles, cobbles, and boulders 

termed "roundstones" (Fernald, 1929; Love, 1956b) 

 set in a sandstone matrix (figs. 4 and 5). The
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B9

FIGURE 3. Quartzite roundstone conglomerate in the Pinyon Conglomerate along the South Fork of Fish Creek. Note crude

stratification and general scarcity of sandstone beds.

roundstones are packed closely together; in most 

outcrops they show a pronounced imbricate arrangement (fig. 4), and in a few outcrops, crossbedding. 

The stones are marked by pressure marks and by 

extensive cracking and crushing (figs. 4 and 5).

SIZE, SHAPE, AND SURFACE MARKINGS OF ROUNDSTONES

The long dimension of quartzite roundstones was 

systematically measured at stations throughout the 

Harebell Formation and the Pinyon Conglomerate 

(fig. 2). In Jackson Hole, the largest roundstones 

were as much as 21 inches in length. At one station 

(56) north of the Teton Range, several large sandstone boulders as much as 90 inches in length and 

one large quartzite boulder 50 inches in length were 

seen (fig. 6) ; none of the other quartzite roundstones exceeded 18 inches in length. Generally, 

roundstones of less common rock types in the conglomerates are smaller than those of the accompanying quartzite, but in the southern facies of the 

Pinyon Conglomerate those of volcanic rock are as 

long as 12 inches.

Three-dimensional measurements were made to 

determine the shape of quartzite roundstones at stations 1, 4, and 57. Zingg plots (PettiJohn, 1957, p. 

54-57) show nearly identical shape distributions for 

all three stations, with most roundstones at each 

locality being oblate, or flattened (fig. 7). Inspection 

of roundstones at many other stations indicates the 

prevalence of oblate shapes.

Surfaces of the quartzite roundstones show crescentic percussion marks, pressure marks, and polish 

(fig. 8). The crescentic percussion marks are curvilinear cracks which typically are 1-3 cm long and 

about 1 mm deep (fig. 8A). Counts at eight stations 

show that about 5 percent of the quartzite stones 

bear at least a few percussion marks. Similar markings were described by Klein (1963), who considered them to result from impact during transport. 

Klein reported that percussion marks are known 

mainly from fluvial deposits, where the energy required to produce them is most commonly available. 

The marks may therefore be evidence of fluvial 

transport.

479-609 O - 72 - 3
BIO GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 4. Typical conglomerate containing well-rounded moderately sorted quartzite roundstones in hard sandstone matrix,

Harebell Formation north of Blackrock Creek.

1-2 cm across and are slightly indented below the 

surrounding surface. On roundstones extracted from 

the matrix each mark is located where the stone 

touches another stone. Similar marks have been described by Klein (1963) and Turnit (1968), both of 

whom concluded that the marks were caused by 

pressure solution.

The third surface marking, polish, occurs on a 

small percentage of the stones. Under the binocular 

microscope, the polished areas are seen to consist of 

parallel striae or grooves about 0.1 mm wide and as 

much as 1 cm long. In some examples two striae 

sets of different orientation are superposed. Similar 

paraflel striae sets have been described by Judson 

and Barks (1961) and Clifton (1965), who suggested tectonic movement or compaction as a probFlGUBE 5. Typical shapes and rounding of quartzite stones able Cause 

from conglomerate of the Harebell Formation, Whetstone 

Mountain. Pocklike spots are pressure marks. LITHOLOGY OF ROUNDSTONES

Pressure marks are found on most roundstones in One hundred roundstones were identified in each 

the conglomerates (figs. 4, 5, and SB). Most are of 98 counts in the conglomerates (table 2). Quartz-
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS Bll

B

FIGURE 6. Large quartzite boulder in Pinyon Conglomerate 

north of the Teton Range. A, Photograph shows size, rounding, and percussion marks. B, Photomicrograph shows same 

boulder to be orthoquartzite with detrital grain outlines 

and quartz cement. Crossed nicols.

ite was found to be the most abundant rock type 

everywhere; lesser quantities of soft sedimentary 

rocks (limestone, sandstone, shale, and chert), volcanic rocks (welded tuff and porphyritic rocks), and 

plutonic rocks (granitic rocks and gneiss) were 

found at most localities. The less common roundstone types were used to define three conglomerate 

lithofacies (figs. 9 and 10) :

1. A western facies, north of the Teton Range, 

characterized by about 20 percent soft sedimentary roundstones and only very few volcanic roundstones.

2. A northern facies, generally north of Spread 

Creek in Jackson Hole, characterized by few 

soft sedimentary roundstones and generally 5

STATION i

i.o

0.8

0.6

0.4

0.2

C3 

00.6

STATION 4 ^

0.4

cr

U0.2

STATION 59

1.0

0.8

0.6

0.4

0.2

Oblate

®

Bladed

Equant

Prolate

Oblate . . .

Bladed

1 1

Equant

Prolate

Oblate *: .

Bladed

Equant

Prolate

0.2 0.4 0.6 0.8 

SHORT AXIS/INTERMEDIATE AXIS (C/B)

1.0

FIGURE 7. Zingg plots of quartzite roundstone dimensions 

at three stations. A=long axis; ^^intermediate axis; C= 

short axis. Circle is average shape at station.
B12 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

percent or less total volcanic roundstones. 

Welded-tuff roundstones are very rare in the 

northern facies.

3. A southern facies, extending from Spread Creek 

to the Gros Ventre River, characterized by few 

soft sedimentary roundstones and generally 

more than 5 percent total volcanic roundstones. 

Among the volcanic roundstones, welded tuff 

is conspicuous throughout the southern facies. 

These characteristics are easily observed in the 

field and are useful in mapping the extent of 

each facies.

A more detailed summary of roundstone lithology 

data for the northern and southern facies is presented in figure 10.

B

FIGURE 8. Surface markings on quartzite roundstones. A, 

Crescentic percussion marks; B, pressure marks.

Statistical analysis of the pebble-count data supports the differentiation of the conglomerates into 

regional facies rather than stratigraphic units. Tests 

(Freund, 1960, p. 260-271) were made for differences in roundstone lithology between the northern 

and southern facies (table 3); they were not made 

for the western facies because of insufficient data. 

These tests show that:

1. The percentage of quartzite is significantly greater in the northern facies than in the southern 

facies.

2. The percentage of other sedimentary rocks is 

possibly greater in the southern facies than in 

the northern facies.

3. The percentage of total volcanic roundstones is 

significantly greater in the southern facies than 

in the northern facies.

In the northern facies, where the Pinyon directly 

overlies the Harebell, tests showed no significant 

differences between roundstone lithology in the 

Harebell Formation and that in the Pinyon Conglomerate (table 3). An additional qualitative test 

is provided by the abundance of welded-tuff roundstones, which were found to be sparse in both the 

Harebell and the Pinyon.

PETROGRAPHY OF ROUNDSTONES

Quartzite roundstones from each conglomerate 

facies were studied in thin section and freshly broken hand specimens. Each facies contains quartzite 

roundstones with a similar range of colors, microscopic textures, and feldspar contents (fig. 11). Predominant colors observed are white, gray, green, 

pink, red, brown, and black. Quartzite microtextures 

include detrital, solution, and metamorphic (based 

on the presence of metamorphic micas). Feldspar 

contents range from 0 to 20 percent or more by 

visual estimation; both orthoquartzites (fig. 12A and 

B) and feldspathic quartzites (fig. 12C and D) are 

common.

Surfaces of freshly broken orthoquartzite roundstones are commonly vitreous and may be any color 

mentioned in the preceding paragraph. Wellrounded undulose quartz with abundant quartz overgrowths or quartz cement forms the most common 

detrital microtexture (fig. 12A). Some orthoquartzites also contain interstitial sericite or scattered 

clots of carbonate; others show conspicuous solution 

textures, including extensive suturing, annealing, 

and recrystallization of grain margins. Surfaces of 

freshly broken subfeldspathic and feldspathic 

quartzite roundstones are commonly either dull or 

vitreous and also may be any color mentioned previously. Many feldspathic quartzites, however, are 

pink or red. Angular grains of plagioclase, micro-
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B13

TABLE 2. Composition (in percent) of roundstones counted in the western fades (Pinyon Conglomerate), the northern fades 

(Harebell Formation and Pinyon Conglomerate), and the southern fades (Pinyon Conglomerate)

[Stations located in fig. 2 ; 100 roundstones were identified at each station, x, arithmetic mean; s, standard deviation ; s2 , variance; Tr., trace. Leaders

(......) indicate not present]

Station 

No.

Quartzite

Sedimentary rocks

o <u 

g S Plutonic 

1 £ rocks1

1 § 1 -3 3 .s a - js o

U W >J W B

Volcanic rocks

i' It 1 PH B

Western facies (Pinyon Conglomerate)

53.........

54

56.........

x. ............

77

.....73

....76.33

2 15 3 1 21 3 

1 13 1 3 18 3 

Tr. 22 Tr. 2 24 3

1.00 16.67 1.33 2.00 21.00 3.00

Tr. 

Tr

Tr.

Tr. 

2 2 

Tr.

0.67 0.67

Northern facies (Harebell Formation)

15 

17.........

31.........

34 

39 

41.........

49.........

52.........

57 ..

59.........

60 

73 

75 

76.........

77 

78 

247A......

247B .

248.........

260 

265 

267 

268A......

268B......

269 

270A .

270B 

271 

274A......

274B ..

275A......

275B......

277 

S 

.....92

.....93

.....97

.....87

.....94

.....94

....98

 96

....93

....97

....99

....95

....98

.....94

.....94

.....96

....95

.....93

.....98

.....98

.....96

.....92

....97

....94

....97

....94

.....93

.....98

 96

.....98

....98

.....95

.....99

..... 2.59 

.... 6.68

2 .... 13 2 

2 2

1 .... .... 1

6 .... .... 6 1 

2 .... .... 2

3 .... .... 14 1 

1 .... .... 1

1 .... Tr. 1

2 Tr. .... 2 Tr.

2 9 1

11 i

i .... .... i i

i .... .... i i

1 .... ' 1 2 

2 .... 1 3

Tr. .... .... .... Tr.

1 .... 1 2 

1 1 .... 1 3 

1 1 .... .... 2 1 

2 .... .... 2 

1 .... .... 1

1 .... .... 1

1 1 .... 2

1 1

1 .... .... 1

1 .... .... 1

0.15 0.91 0.09 0.30 1.45 0.30 

1.16 .... .53 1.33 .63 

1.34 .... .28 1.76 .28

Tr.

Tr.

Tr.

3 3 

5 5 

2 2 

6 6

4 4

1 1 

1 1 

3 3 

5 5 

3 3

1 1 

2 2

4 4 

4 4

3 3 

3 3 

4 4 

2 2 

2 2

2 2 

5 5 

Tr. Tr.

4 4 

2 2

5 5 

5 5 

2 2 

3 3

1 1 

1 1 

5 5 

1 1

2.85 2.85 

1.64 1.64 

2.70 2.70

Northern facies (Pinyon Conglomerate)

38 

40 

44

47.........

50 

256A......

259A

259B .

272A ..

272B......

278 

88 

.....96

95

96

.....96

....97

94

no

 98

.....96

....94

2 .... 1 3 

Tr. 1 1 Tr. 

1 .... .... 1 1 

2 2 

"- 1 Tr. .".".".' 1 Tr.

Tr. .... Tr.

2 .... .... 2 Tr. 

2 Tr. .... 2 

2 .... .... 2

1 2 .... .... 3 1 

1 .... .... 1 

2 2 .... .... 4

1 

Tr.

9 9 

3 3 

3 3 

2 2 

1 1

3 4 

1 1 

4 4 

5 5

2 2 

2 2 

3 3 

2 2

Sedimentary rocks

Station 

No.

Quartzite

Q) Q)

1 1 

I 1 1 U M J

j; o 

w B

Northern facies (Pinyon Conglomer

«... ..........

1 

2.........

10 

11 

14 

21 

64 

71.........

72A

72B......

Q7

QQ

89 

90 

92.........

95 

96

97.........

172 

173.... 

180 

181. 

183A .

185 

193A ..

193B ..

194 

195. ...

203.........

204 

206 

210A

ZlUJt>......

212

213 

214A.... ..

214B

215B 

219 

222A ..

222B ..

223A......

223B ..

s......... ... .

S2.. . ....

.....95.00

..... 2.61

..... 6.83

.92 

.....77

.....86

.....86

.....92

.....83

.....90

.....89

.....94

....91

.....88

.....78

91

.....88

.....93

 92

.....85

.....89

.....90

.....88

.....95

.... 88

....90

.....91

.....91

.....84

.....93

....95

.....96

.....93

.....92

.....92

.....89

.....91

89

92

95 

.....96

.91 

94

94 

.....93

.....84

.....89

......89

 89

......89.63

..... 4.37 

 19.07

0.23 1.31 Tr. 

.85 ....

.73 ....

Southern facies

5

2 

1

1

1 

1 

111

2

1 

4 

1 1 

1

Tr. 3

3

1

1

2

1

2

1

2 1 

1

1

111 

3 

2 

1

1 2

1 1

1 

1 2

2

1

5 

2 

1 

1

0.16 1.69 

1.18

1.40

Plutonic 

rocks1

Volcanic rocks

 o

VH-I

2s

Oif

'E »

|l |

ite ) Continued

0.15 0.08 3.07 3.15 

2.10 2.12

4.41 4.47

(Pinyon Conglomerate)

1 1 

5 10 

4 6 

1

5 6

2 3

1 2

1 4

1 3 

1 2 

5 9 

2 

1 2

Tr. Tr. 

3

3

1

1

1 3 

3 4

2

1 2 

1

3 

1 2

1

3 

3 

1 3 

1 2

3 

2

1 1 

1 1 

1 1

1 2 

3

2 

1 2

4 9 

1 3 

1 

1

0.14 1.22 0.14 0.92 2.43 

1.26 .... 1.41 2.25 

1.59 .... 1.99 5.08

1 

4 

3 

1 

1

2 

2

Tr. 

Tr.

i

2 

Tr.

1 

1 

1

Tr. 

Tr.

2

Tr.

Tr.

Tr. 

1 

1

1 

1 

Tr. 

1

0.55 

.89 

.79

1 

3 

Tr. 

2 

Tr.

1 

Tr. 

Tr. 

Tr. 

1

Tr. 

2 

1 

1

1

1 

3 

2 

3 

2

1 

1 

1 

2 

Tr.

1 

2 

2 

2 

2

1 

2 

Tr.

1 

2

2 

2 

2

Tr. 

Tr.

1 

1 

Tr. 

2 

3

2

1 

1 

4

1.33 

.99

.97

5 6 

6 9 

12 12 

10 12

7 7

5 6 

12 12

8 8 

7 7 

5 6

6 6 

7 9 

12 13 

4 5 

9 10

6 7 

4 7 

3 5 

11 14 

6 8

9 10 

10 11 

3 4 

7 9 

6 6

4 5 

5 7 

13 15 

2 4 

1 3

2 3 

2 4 

5 5 

4 5

7 9

4 6 

6 8 

11 13

7 7 

4 4

1 2 

5 6 

6 6 

2 4 

2 5

4 6 

6 7 

9 10 

5 9

6.06 7.39 

3.09 3.07 

9.56 9.45

aPlutonic refers to granitic and gneissic rocks and their relatives, except for stations 41 and 272A, where diabase was recorded.

TABLE 3. Student's t tests for significant differences in roundstone lithology between the northern and southern fades and 

between the Harebell Formation and Pinyon Conglomerate within the northern fades

[x, arithmetic mean ; s", variance. Mean and variance are in percent. Numbers in parentheses are number of counts]

Northern and southern facies

Roundstone lithology

Soft sedimentary rock..... 

Volcanic rock........ .....

Northern 

facies (46)

x

.. 1.52 

.. 2.93

sa

6.61 

1.63 

3.13

Southern 

facies (49)

x

89.63 

2.43 

7.39

s"

19.07 

5.08 

9.45

Student's t 

value

7.74 

2.44 

8.73

Harebell and Pinyon within the northern facies

0 . .,, Harebell (33) Significance

0.01 

.10 

.01

~x

95.39 

1.45 

2.85

s2

6.68 

1.76 

2.70

Pinyon (13)

x

95.00 

1.69 

3.15

s"

6.83 

1.40 

4.47

Student's t 

value

0.01 

.55

.51

Significance

None 

None 

None
B14 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

R. 114 W, 30' R. 113 W,

NORTHERN FACIES 

Few soft sedimentary roundstones 

< 5percent total volcanic roundstones 

-Welded-tuff roundstones rare

' = 46 S

WESTERN FACIES

R. 117 W.

NORTHERN FACIES

l.'Xt rtv AA WESTERN FACIES 

Abundant soft sedimentary roundstones/'

Few volcanic stones

N=3

SOUTHERN FACIES 

Few soft sedimentary roundstones 

<5 percent total volcanic roundstones 

Welded-tuff roundstones common

T, 41 N 

SOUTHERN FACIES EXPLANATION

Conglomerate facies

cp, Pinyon Conglomerate 

ch, Harebell Formation

Contact 

Dashed where inferred

ROUNDSTONE COUNT DATA AT EACH STATION 

Soft sedimentary rock abundant (>10 percent)

<5 >5 

Percentage of total volcanic rock

A

Observed

but rare

Welded tuff

ABBREVIATIONS USED IN SUMMARY DIAGRAMS 

Q, quartzite P, plutonic rock N, number of counts 

V, volcanic rock S, soft sedimentary rock

FIGURE 9. Classification of the conglomerates of the Harebell Formation and the Pinyon Conglomerate into 

three lithofacies according to proportions of minor roundstone types present.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B15

45

40

35

30

25

20

15

10

30 -

25

z 

g

iW 20

15

10

75

s2=6.61 

N=46

I 1 T I I

= 1.52 

2 = 1.63

I I I

x=2.93 

S 2=3.13

NORTHERN CONGLOMERATE FACIES

= 89.63 

2 = 19.07

x-2.43 

s2=5.08 s2=9.45

80 90

QUARTZITE, IN PERCENT

100 0 2 4 6 8 10

SOFT SEDIMENTARY ROCK, IN PERCENT 

SOUTHERN CONGLOMERATE FACIES

4 8 12 16 

VOLCANICS.IN PERCENT

FIGURE 10. Frequency distributions of quartzite, soft sedimentary rock, and volcanic roundstones in the northern and 

southern conglomerate facies. Frequencies are based on counts of 100 roundstones each as recorded in table 2. x, arithmetic mean; s2 , variance; N, number of counts.
B16 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

COLOR TEXTURE FELDSPAR CONTENT 

(PERCENT)

WESTERN 

FACIES

NORTHERN 

FACIES

SOUTHERN 

FACIES

FIGURE 11. Summary of color, texture, and feldspar content of quartzite roundstones from conglomerates in the western 

facies (two stations), the northern facies (five stations), and the southern facies (three stations). Number in lower left 

corner of each block is the number of specimens examined. Texture: D, detrital; S, solution; M, metamorphic.

cline, and detrital muscovite are common to abundant as seen under the microscope (fig. 12(7), and 

many feldspathic quartzites are fine grained (fig. 

12D). Solution textures and sericitic or chloritic 

matrix are common. A metamorphic origin is indicated for those orthoquartzites and feldspathic 

quartzites which exhibit a tectonic fabric or contain 

xenoblastic mica (fig. 121? and D), most commonly 

fine-grained biotite.

In hand specimen and thin section, most of the 

quartzite roundstones do not show unique characteristics that might aid in assigning them to a 

definite stratigraphic source. A few roundstones of 

chert and jasper pebble conglomerates do occur, and 

the jasper pebble conglomerates might be referred

to similar rocks interbedded with quartzites of uncertain age in the Bayhorse region of central Idaho 

(W. H. Hays, oral commun., 1971). The quartzite 

roundstones are similar, however, to the following 

four broad groups of pre-Cretaceous quartzites 

found north and west of northwestern Wyoming: 

(1) Paleozoic Flathead, Kinnikinic, Swan Peak, 

and Quadrant Quartzites, (2) Precambrian and 

Cambrian quartzites, (3) quartzites of the Precambrian Belt Supergroup, and (4) pre-Belt quartzites. 

The Cambrian Flathead Quartzite contains thin, 

discontinuous arkosic lenses at the base, but most 

of it is pink, tan, and gray quartz sandstone and 

orthoquartzite (Hanson, 1952; Miller, 1936; Parkinson, 1958). Probably more significant as a possible
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B17

FIGURE 12. Photomicrographs of the principal types of texture and mineralogy exhibited by the quartzite roundstones. 

A, Orthoquartzite with many detrital grain outlines and 

quartz cement. B, Metaquartzite consisting mostly of quartz 

grains with sutured and partially recrystallized grain contacts and scattered xenoblastic muscovite. C, Quartzite 

with as much as 20 percent feldspar; indented solution

contacts between grains. D, Fine-grained feldspathic (10- 

20 percent) metaquartzite with detrital muscovite flakes 

and xenoblastic biotite. All samples are from the northern 

facies: A and B are from the Harebell Formation on Whetstone Mountain (sta. 34) ; C and D are from the Piny on 

Conglomerate (sta. 48). Crossed nicols. M, muscovite; F, 

feldspar.

479-609 O - 72 - 5
B18 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

source of the quartzite roundstones is the more than 

1,000 feet of Ordovician quartzites known to extend 

over a wide area of Idaho and northern Utah 

(Ketner, 1966, 1968). These include the Kinnikinic 

Quartzite of Idaho, typically a light-gray to white 

quartz-cemented orthoquartzite (Hobbs and others, 

1968), and the Swan Peak Quartzite of southeastern 

Idaho and northern Utah, which also contains much 

light-colored orthoquartzite (Vandorston, 1970). 

The Pennsylvanian Quadrant Quartzite also contains 

gray quartz sandstone and orthoquartzite. Many of 

the orthoquartzite roundstones in the Harebell and 

Pinyon conglomerates, including the large quartzite 

boulder north of the Teton Range (fig. 6), resemble 

the Paleozoic quartzites.

The Precambrian and Cambrian quartzites include 

the Precambrian and Cambrian Brigham Quartzite, 

the Precambrian Mutual Formation, and additional 

Precambrian quartzites below the Mutual in the 

region around Pocatello, southwest of Blackfoot, 

Idaho (Crittenden and others, 1971). Samples of the 

Brigham that I examined are light-gray orthoquartzites, but the Mutual Formation consists of much red 

feldspathic quartzite, some of it coarse grained to 

conglomeratic. Low-grade metamorphism was comparable to that in the conglomerate roundstones, being marked generally by development of abundant 

sericite.

The Precambrian quartzites of the Belt Supergroup of the Lemhi Range in Idaho include the 

Lemhi and Swauger Quartzites (Ross, 1947). Those 

that I examined display a wide range of colors and 

feldspar contents and a low grade of metamorphism 

comparable to that found in many roundstones from 

the Harebell and Pinyon conglomerates. Many contain abundant feldspar and metamorphic muscovite 

(Ross, 1947). Also, some quartzites in the LaHood 

Formation of the Belt Supergroup in southwestern 

Montana are feldspathic and may resemble the 

roundstones in the Harebell and Pinyon (McMannis, 

1963).

The pre-Belt quartzites consist of the quartzites 

in the Cherry Creek Group and perhaps other unnamed metaquartzites from the pre-Belt terrane 

west of Yellowstone National Park. These quartzites 

are gray, green, or white; they show evidence of intense deformation; and they may contain high-grade 

metamorphic minerals (Reid, 1957, p. 5; Heinrich 

and Rabbitt, 1960, p. 5; Heinrich, 1960, p. 22). Only 

a few quartzite roundstones found in the Harebell 

and Pinyon resemble the pre-Belt quartzites.

A collection of 43 roundstones of soft sedimentary 

rocks was also studied in thin section. Many of these 

were collected from the Pinyon Conglomerate at the

north end of the Teton Range (sta. 53, 54, and 56) 

and at Mount Randolph (sta. 62). The roundstones 

examined consisted of limestone, sandstone, phosphatic shale and siltstone, and chert, in decreasing 

order of abundance. Among the limestones, skeletal 

(fig. ISA) and oolitic limestones are the most common, but intraclastic limestone, micrite, and dismicrite are also present. Fragments of bryozoans, 

bivalves, crinoid stems, corals, and foraminifers are 

abundant in the skeletal limestones. In general, the 

petrography of the limestones resembles that of 

samples collected from the Mississippian Madison 

Limestone at the north end of the Teton Range. Some 

of the sandstones are phosphatic (fig. 13#), but 

many others are quartzitic, subfeldspathic, and 

chert bearing, with quartz or calcite cement. Most 

of the siltstones and shales examined are also phosphatic, and like the phosphatic sandstones, they resemble similar rocks in the Permian Phosphoria 

Formation. Chert roundstones are commonly derived from silicified limestone; some contain relict 

fossils.

Twenty-seven roundstones of plutonic rocks from 

widely separated localities were studied by means of 

thin sections and hydrofluoric acid-etched, cobaltinitrite-stained slices. The rocks fall into three textural categories: hypidiomorphic-granular igneous 

rocks (19), gneisses (five), and diabases (three). 

The hypidiomorphic-granular rocks range from 

granite to granodiorite, with biotite being the most 

common mafic mineral. Euhedral phenocrysts of 

both potassium feldspar and plagioclase are common, as are graphic intergrowths of quartz and 

feldspar (fig. 13C). An unusual feature seen in one 

pebble is the intrusive contact between grandodiorite and quartzite (fig. 13.D). The gneissic roundstones consist of quartz-, feldspar-, and biotite-rich 

layers, and the diabases show typical subophitic textures of abundant plagioclase laths set in a mosaic 

of mafic minerals. Evidently most of the plutonic 

rocks were derived from small igneous plutons, some 

of which intruded the quartzite source terrane.

Two hundred and six roundstones of volcanic rock 

were studied by means of hydrofluoric acid-etched, 

cobaltinitrite-stained slices and thin sections. A wide 

variety of rock types were identified: porphyritic 

rhyolite, rhyodacite, dacite, trachyte, trachyandesite, and dacite as well as welded tuffs and volcanic 

breccias (table 4). In general the volcanic roundstones fall into four broad groups: (a) porphyritic 

with modal quartz (fig. 14A), (b) porphyritic with 

no modal quartz (fig. 14#), (c) welded tuffs (figs. 

14C and D), and (d) breccias and miscellaneous 

lithologies.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS

i" ;>-- -^ 

B19

FIGURE 13. Photomicrographs of roundstones derived from 

sedimentary (A and B) and plutonic (C and D) rocks. 

A, Skeletal limestone containing Paleozoic fossils; plain 

light. B, Phosphatic sandstone: plain light. C, Granite with 

hypidiomorphic and myrmekitic textures; crossed nicols. 

D, Granodiorite intrusive contact with quartzite; crossed

nicols. A and C are from the northern facies (Pinyon Conglomerate) on Mount Randolph (sta. 62); B is from the 

western facies (Pinyon Conglomerate, sta. 56) ; and D is 

from the northern facies (Harebell Formation) on Whetstone Mountain (sta. 34).
B20 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 14. Photomicrographs of typical volcanic roundstones. A, Porphyritic dacite with typical partially resorbed 

quartz phenocryst; crossed nicols. J5, Porphyritic andesite 

with abundant zoned plagioclase phenocrysts; crossed nicols. C, Welded tuff with feldspar crystals, flattened pumice 

fragments, and flattened devitrified shards, which are typical in the southern conglomerate facies; plain light. D, 

Welded tuff with large uncollapsed pumice fragments; 

plain light. A is from the northern facies (Pinyon Conglomerate, sta. 40) ; B, C, and D are from the southern 

facies (Pinyon Conglomerate, sta. 71). Q, quartz; P, plagioclase; pum, pumice.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B21

The sample of volcanic roundstones was not randomly selected and is only roughly indicative of the 

proportions of each rock type present. The 5 percent 

welded tuff recorded in table 4 represents every 

roundstone of this lithology that I saw in the northern fades, and roundstone counts indicate that the 

proportion of welded tuff is much less. Table 4 does 

suggest a predominance of porphyritic rocks with 

modal quartz over those with no modal quartz in 

roundstones of the northern facies and the reverse 

relationship in the southern facies.

TABLE 4. Proportions of volcanic rock types among roundstones from the northern and southern conglomerate facies

[Based on identifications of HF-etched, cobaltinitrite-stained slices. Figures 

do not total to 100 percent because of rounding. Numbers in parentheses 

are number of specimens]

Roundstones of quartz-bearing porphyritic volcanics contain 1-10 percent euhedral phenocrysts of 

quartz which show varying degrees of resorption. 

Rapid rock analyses of five such roundstones show 

ranges of 62-68 percent SiO2, 15-16 percent A12O3 , 

and 5-6 percent Na2O-(-K2O (table 5), values which 

compare closely with those for dacites and rhyodacites (Nockolds, 1954, table 2). Fresh to altered 

phenocrysts of plagioclase and potassium feldspar 

are commonly abundant and may comprise as much 

as 40 percent of the rock. Plagioclase is almost 

everywhere zoned and may range up to An50 . Potassium feldspar occurs mostly as euhedral phenocrysts 

but also as rims on plagioclase and in micrographic 

intergrowths with quartz. Stained slices also suggest 

fine-grained potassium feldspar in the groundmass. 

Mafic phenocrysts, which commonly do not exceed a 

few percent of the rock, consist of pyroxene, amphiboles, and biotite. Opaque oxidation rims commonly 

accompany mafic phenocrysts, and chlorite, calcite, 

and apatite may replace the phenocrysts. The 

groundmass is typically altered to microcrystalline 

quartz, chlorite, clay(?) minerals, and disseminated 

iron oxides, although relict feldspar microlites can 

be seen in a few thin sections. In addition to the 

phenocryst and groundmass constituents, angular 

fragments of quartzite, sandstone, and other volcanics are commonly contained within roundstones

TABLE 5. Rapid rock analyses (in percent) of volcanic roundstones from conglomerates of the Harebell Formation and the

Pinyon Conglomerate

[Analysts: Leonard Shapiro, P. L. D. Elmore, G. W. Chloe, J. A. Kelsey, S. D. Botts, H. Smith, and Lowell Artis]

Bxick type

Potassium 

feldspar

(fraction 

of total 

feldspar)

Percent of rock type in 

conglomerate facies

Northern Southern 

facies (79) facies (127)

Porphyritic volcanics with modal quartz ^1

Dacite.................. .......................................... 2<%

Total....................................................................

Porphyritic volcanics with modal quartz <1

Andesite................ ......................................... 2<%

Total........... .......... ... .... ............................

Welded tuffs...-... . ............. . ............ ..

Volcanic breccias and miscellaneous lithologies .......

Abundant potassium feldspar in matrix. 

zNo potassium feldspar in matrix.

percent

15

5

72

percent

1

18

4

11

9

5

27

8

13

44

26

4

Porphyritic volcanics Porphyritic volcanics 

with modal quartz with no modal quartz

Sample No................

Si02 ...................

AloOs-...-..--

Fe2 03--...-..--

FeO....................

MgO...................

CaO....................

Na2 0...............

K2 0....................

H2 0 ................

H2 0+................

Ti02...................

P2 05 --...-...--

MnO...................

C02 ..... ...............

Sum........

Sample 

No.

1. ......

2.......

3.......

4.......

5.......

6.......

7.......

8.......

9.......

10.......

11.......

1 2

64.1 62.4 

15.4 16.3 

3.3 2.5 

2.9 3.1 

1.9 2.0 

1.3 3.3 

2.1 3.0 

3.9 3.2 

1.7 .47 

2.6 1.8 

.61 .60 

.21 .20 

.05 .10 

<.05 .95

100 100

Field 

No.

....... ..........H-15-C2

...... ...........H-15-C4

............... ..H-39-C2

P d7 P9

....... ..........P-50-C2

P

71 pi o

............. ...FF-SF-CC-17

.................FF-SF-CC-26

.................P-71-C3

.................P-71-C13

.................FF-SF-CC-28

345 67

64.4 64.9 68.0 61.2 61.2 

15.8 15.6 14.5 16.2 16.0 

1.5 3.1 2.1 3.2 1.2 

3.4 2.3 2.2 2.7 4.7 

2.1 2.0 1.7 2.0 2.2 

2.0 2.7 2.2 3.3 3.2 

3.3 2.4 2.7 2.1 2.3 

2.7 2.5 3.2 3.1 2.7 

1.3 .95 1.0 .94 1.4 

2.3 2.0 1.9 2.4 3.2 

.77 .60 .46 .75 .61 

.26 .21 .12 .26 .26 

.06 .12 .05 .11 .13 

.09 .18 <.05 1.1 .70

100 100 100 99 100

SAMPLE DESCRIPTIONS

sAtat£nTor "-« *«-

Northern facies (Harebell Formation)

15 Porphyritic rhyodacite. 

15 Porphyritic rhyodacite (?). 

39 Porphyritic rhyodacite.

Northern facies (Pinyon Conglomerate)

46 Porphyritic rhyodacite (?). 

50 Porphyritic rhyodacite.

Southern facies (Pinyon Conglomerate)

71 Porphyritic andesite. 

183 Porphyritic trachyandesite. 

183 Porphyritic andesite. 

71 Dacitic welded tuff. 

71 Rhyolitic welded tuff. 

183 Do.

8

62.0 

16.3 

2.9 

3.6 

2.2 

2.9 

2.0 

2.3 

1.1 

2.8 

.65 

.24 

.13 

.94

100

Welded tuffs

9

62.4 

15.5 

1.9

4.0 

1.8 

2.8 

2.6 

3.2 

.73 

2.7 

.78 

.39 

.11 

.78

100

10

69.6 

15.7 

1.0 

.96 

.46 

1.6 

3.2 

5.5 

.25 

1.0 

.44 

.10 

.08 

.05

100

11

69.5 

14.6 

1.5 

1.6 

.83 

1.5 

3.4 

5.1 

.24 

1.0 

.52 

.12 

.05 

<.05

100
B22 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

of quartz-bearing volcanic rock. The presence of 

quartzite fragments similar to the quartzite roundstones of the conglomerates is significant in that it 

suggests a common source for roundstones of both 

quartz-bearing porphyritic volcanics and quartzite.

Except for the sparsity of quartz phenocrysts, 

roundstones of porphyritic rock with no modal 

quartz are petrographically similar to those with 

modal quartz. Rapid rock analyses of three such 

roundstones show them to contain 61-62 percent 

SiOo, slightly more than 16 percent A12 03 , and 4-5 

percent Na20+K2 0 (table 5), also comparable to 

dacite (Nockolds, 1954, table 2). Petrographic study 

of thin sections and stained slices, however, results 

in classification of most of these rocks as andesite or 

trachyandesite (table 4). Although chemical evidence suggests that these rocks may be characterized 

as dacites, I will refer to them by their petrographic 

designation, andesite, to distinguish them from the 

porphyritic rocks with modal quartz previously described as dacites. Petrographic and chemical affinities suggest that both the dacitic and andesitic 

roundstones were derived from the same volcanic 

terrane; however, the general absence of quartzite 

fragments in the andesites suggests derivation from 

different sources.

Most of the welded-tuff roundstones are marked 

by numerous conspicuous dark pumice fragments; 

commonly the pumice fragments are collapsed and 

drawn out to form a pronounced compaction layering 

that gives the rock a distinctive striped appearance. 

In a few stones, equant angular pumice fragments 

retain their original form. Under the microscope, 

many stones are seen to contain numerous relict 

shards: hook- and spicule-shaped structures which 

commonly show deformation and flattening so that 

they conform to the plane of compaction layering. 

The shard interiors are now filled with quartz and 

feldspar devitrification products; no trace of glassy 

material was seen. A few highly altered plagioclase 

euhedrons commonly occur in the welded tuffs, and 

quartz euhedrons occur more rarely. Sparse mafic 

phenocrysts consist of light-green augite, brown and 

light-green amphiboles, and sparse pleochroic lightbrown to deep-blue amphibole (riebeckite?). Many 

mafic phenocrysts are entirely replaced by chlorite, 

iron oxides, and apatite. The matrix of the welded 

tuff is generally a highly altered mass of microcrystalline quartz, chlorite, and iron oxides, with scattered veinlets and patches of calcite. Cobaltinitrite 

staining also reveals abundant potassium in the 

matrix. Rapid rock analyses of three stones showed 

widely varying Si02 contents from about 62.5 to 

nearly 70 percent (table 5).

The petrography and chemistry of the volcanic 

roundstones is broadly indicative of two possible 

sources: (1) the Upper Cretaceous Elkhorn Mountains Volcanics and Livingston Group for volcanic 

rocks that contain no modal quartz (andesitic rocks) 

and for welded tuffs, and (2) an unknown source for 

volcanic rocks that contain modal quartz (dacitic 

rocks).

The porphyritic roundstones that contain no modal 

quartz are petrographically similar to the widespread 

andesitic rocks of the Elkhorn Mountains Volcanics 

described by Klepper, Weeks, and Ruppel (1957) 

and by H. F. Barnett (in Robinson, 1963). Chemical 

analyses of two "typical andesites" from the Elkhorn Mountains Volcanics (Robinson, 1963, table 

9) are comparable to those obtained for andesitic 

roundstones from the Harebell and Pinyon (table 5). 

The welded-tuff roundstones are petrographically 

similar to the abundant welded tuffs found in the 

middle member of the Elkhorn Mountains Volcanics. 

Chemical analyses of welded tuffs in the Elkhorn 

Mountains Volcanics (Robinson, 1963, table 9; 

Smedes, 1966, table 2) show them to range in composition from rhyodacitic to rhyolitic, a range comparable to that obtained from analyses of three 

welded-tuff roundstones from the conglomerates of 

Jackson Hole (table 5). Andesite and welded tuff 

detritus probably derived from the Elkhorn Mountains Volcanics is also found in the Livingston Group 

volcaniclastic sediments (Roberts, 1963). In contrast, rhyodacites and dacites comparable to the 

quartz-bearing porphyritic roundstones found in the 

conglomerates are not known to be abundant in the 

Elkhorn Mountains Volcanics (Klepper and others, 

1957). Hence, a second, unknown source must be 

postulated for the abundant quartz-bearing porphyritic roundstones found in the conglomerates.

PETROGRAPHY OF MATRIX

The matrix of the conglomerates, as seen in thin 

section, consists of poorly rounded, moderately well 

sorted sand grains set in either a calcite cement or 

a fine-grained argillic matrix. The grains consist 

of abundant quartz, feldspar, altered rock fragments, and chert, in addition to lesser amounts of 

quartzite, mica, and heavy minerals (table 6; fig. 

15). Most of the clastic constituents, as shown by a 

triangular plot of 36 samples (fig. 16A), fall within 

the subfeldspathic lithic field of the Williams, Turner, and Gilbert (1954, p. 292-293) sandstone classification. A plot of grains, cement, and matrix (<0.02 

mm) reveals two distinct rock types: calcite-cemented arenites and matrix-bound wackes (fig. 

165).
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B23

TABLE 6. Modal composition (in percent) of the sandstone matrix of conglomerates of the northern fades (Harebell Formation and Pinyon Conglomerate) and the southern fades (Pinyon Conglomerate)

[300 points counted per slide. Middle of field number corresponds to station number in fig. 2. Leaders (......) indicate not present]

Field No. Quartz K-feldspar Plagioclase frag^ntg Chert Quartzite Muscovite

Fine-grained 

Biotite altered 

matrix

Calcite 

cement

Heavy 

minerals

Northern facies (Harebell Formation and Pinyon Conglomerate)

H-31-hl...............

31-t/h..............

34 h 2

35-h/t..............

37-hl...............

37-h2

P-38-t/h..............

H-39-tl................

39 12

P-40-h2............. ...

44-h.................

44 h2

47-h.................

48-h.................

H-49-t----......

P-51-t/h..............

62-t/h..............

H-73-t/h.............

P-l-t....................

2-h...................

2-t....................

10-t/h..............

12-t..................

14-h.................

64-t/h..............

71-t..................

88-h.................

89-t/h..............

90-t/hl............

90 t/h2

91-t/hl............

92-t/h..............

95 t/h3

96-t/h..............

97-t/hl............

.......... 29.4

......... 42.3

.......... 31.0

.......... 50.0

.......... 45.6

.......... 34.0

.......... 38.6

.......... 43.0

.......... 39.0

.......... 21.0

.......... 32.4

.......... 39.7

.......... 29.4

.......... 40.0

.......... 46.7

......... 48.7

.......... 37.4

.......... 32.3

......... 33.6

.......... 42.0

.......... 41.7

.......... 25.3

.......... 38.4

.......... 36.3

......... 27.0

......... 41.4

.......... 24.7

......... 25.3

......... 31.4

......... 25.4

......... 33.0

......... 27.6

.......... 40.0

......... 31.7

.......... 22.0

.......... 24.3

6.3

6.0

3.0

4.7

1.7

2.0

5.7

6.7

6.7

5.0

5.3

5.0

5.3

4.0

5.0

5.0

4.3

6.7

4.7

3.3

6.3

5.0

4.3

4.0

4.3

5.3

4.3

5.0

5.3

4.3

5.3

5.7

4.0

5.0

5.3

4.0

2.3

.3

1.7

2.0

3.3

2.7

2.0

5.0

5.3

1.3

3.0

3.0

5.0

3.3

2.0

3.3

.3

1.7

4.7

4.0

3.7

2.3

4.3

3.7

2.3

2.0

3.0

4.0

2.3

3.7

2.3

4.3

3.3

4.3

2.0

2.7

15.0

18.7

11.3

4.7

12.3

9.7

13.0

7.0

14.7

10.7

11.0

6.3

6.7

6.0

5.7

4.7

6.3

6.7

Southern facies

4.3

6.7

10.3

8.7

7.7

12.3

9.7

6.0

9.7

8.3

8.7

9.0

5.3

6.7

6.7

9.0

9.7

7.7

5.0

4.3

2.0

2.7

6.7

1.7

6.3

.7

7.0

1.0

4.0

4.3

2.7

.7

7.3

10.0

4.3

11.0

1.3

1.7

4.0

.7

2.7

1.7

2.0

1.0

1.3

1.0

1.3

.7

0.3

.3

.3

.3

.3

.3

.3

1.0

.3

.3

.3

.3

.3

.3

.7

0.7

1.0

.7

.7

.7

.3

1.7

2.7

2.0

.3

2.0

1.3

.3

3.3

.3

1.7

1.3

1.7

23.0

45.3

25.6

25.0

.3

27.7

34.7

24.0

1.3

2.0

32.0

3.7

9.7

29.7

21.7

41.3

13.7

38.0

2.3

.3

9.0

11.7

47.3

2.7

57.0

40.3

6.3

42.7

34.7

6.0

4.3

25.0

0.3

- ..

.3

....

....

.3

.3

1.0

1.7

1.0

\ ....

....

.3

(Pinyon Conglomerate)

4.0

1.3

1.0

5.7

5.7

1.7

1.3

3.0

1.7

4.0

4.3

1.3

2.3

3.7

1.0

2.0

4.0

0.3

.7

1.7

6.0

2.3

.3

2.3

1.0

1.3

3.0

2 0

2.3

1.0

1.3

1.3

0.7

1.3

.3

.7

1.3

1.0

1.0

.3

.3

1.0

1.3

.3

.3

.7

.3

1.3

2.3

1.7

.3

1.3

4.3

.7

.3

2.0

.7

1.7

1.0

2.3

.7

.7

.3

1.0

2.3

0.3

39.3

33.7

.3

.7

4.0

6.7

3.3

1.7

42.7

7.7

2.7

3.7

1.3

45.3

.7

.7

55.3

35.7

23.7

50.7

41.7

43.7

49.0

44.7

47.3

6.7

49.3

20.7

43.7

51.0

51.0

0.3

.3

.7

.7

.7

.7

.7

.3

.7

1.0

1.3

1.0

The quartz grains are everywhere almost evenly 

divided between two varieties which grade into each 

other: (1) quartz with straight extinction, which 

commonly has either straight, smooth, or irregular 

grain boundaries, and (2) quartz with undulose extinction, which generally has irregular grain boundaries. Both fresh and altered grains of orthoclase, 

microcline, perthite, and plagioclase are common, 

and total potassium feldspar generally exceeds plagioclase. Rarely plagioclase grains show normal or 

oscillatory zoning; most show only polysynthetic 

twinning. A wide variety of detritus, much of it unidentifiable, was included under the designation 

"altered fragments." However, grains of altered 

siltstone, volcanic rock with tiny plagioclase laths in 

a chloritic or silicified matrix, sparry calcite, and 

dusty micrite can be positively identified. Most of 

the altered fragments are brown grains composed 

chiefly of chlorite, microcrystalline quartz, and 

traces of carbonate and opaques. Grains identified as

chert include both microcrystalline and chalcedonic 

quartz. Quartzite grains are similar to the quartzite 

pebbles and cobbles described previously. Large 

brown biotite flakes are generally more numerous 

than muscovite.

The sandstone matrix of the conglomerates is 

commonly cemented by sparry calcite which generally is clear but which appears dusty in the finer 

grained parts. Rhombs with high relief, probably 

dolomite, are present but sparse. One sample from 

an outlier of Pinyon Conglomerate at station 87 

proved to be cemented by chalcedonic quartz. In 

samples where calcite is absent, a brown semiopaque 

matrix of clay minerals, microcrystalline quartz, 

disseminated opaque minerals, and possibly additional unidentified minerals occupy the interstices.

Heavy minerals were separated from 16 samples 

of conglomerate matrix by the following sequence 

of operations: Crushing, dissolving the carbonate 

cement in hydrochloric acid, drying, sieving to
B24 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 15. Photomicrograph of typical subfeldspathic lithic 

wacke matrix of conglomerates; northern facies (Harebell 

Formation), station 35 on Whetstone Mountain; crossed 

nicols.

obtain the fractions 0.0625-0.125 mm and 0.125-0.25 

mm, and centrifuging in bromoform. The 0.125- to 

0.25-mm fraction proved to be mainly garnet and 

opaques. The 0.0625- to 0.125-mm fraction contained 

not only garnet and opaques but also significant 

quantities of zircon, tourmaline, sphene, and clinoamphibole (mainly pleochroic dark brown, but also 

light blue green and colorless) in addition to minor 

amounts of epidote, apatite, rutile, and pyroxene 

(table 7). Amphibole was not found in the conglomerate matrix of the western facies; it was found in 

abundance in owe sample only from the northern 

facies; and it was found in all the samples examined 

from the southern facies. The proportion of various 

heavy-mineral species in the samples studied, however, varied greatly. Garnet, sphene, and amphibole 

are generally angular, whereas zircon and tourmaline exhibit both well-formed euhedrons and wellrounded grains.

SANDSTONE

GENERAL DESCRIPTION

Thick beds of gray to tan sandstone crop out as 

low ledges and isolated exposures in the sandstone 

facies below the thick quartzite-bearing conglomerates. Excellent exposures of sandstone are seen in

QUARTZ, CHERT, QUARTZITE

FELDSPAR UNSTABLE ROCK 

FRAGMENTS 

PLUS MICA

GRAINS

B

v. V V V V

CEMENT MATRIX

FIGURE 16. Classification of sandstone matrix of conglomerates, modified from Williams, Turner, and Gilbert (1954, 

p. 292-293). A, Clastic constituents; B, relative proportions 

of grains, cement, and matrix, x, northern facies; , southern facies.

the lower member of the Harebell Formation low on 

the south slopes of Whetstone Mountain and along 

Blackrock Creek just above its confluence with Buffalo Fork. Good exposures of sandstone in the lower 

member of the Pinyon Conglomerate as well as in the 

Harebell Formation are present below the conglomerate north of Upper Slide Lake. Typically the sandstones are medium to coarse grained and may con-
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B25

tain conglomerate, tuff, shale, claystone, coal, and 

sparse limestone lenses. Lenses of conglomerate with 

numerous pebbles derived from Paleozoic and Mesozoic rocks are known in sandstones of the Harebell

TABLE 7. Nonopaque heavy minerals (in percent) in the 

sandstone matrix of conglomerates in the western fades 

(Pinyon Conglomerate), the northern fades (Harebell 

Formation and Pinyon Conglomerate), and the southern 

fades (Pinyon Conglomerate)

[0.0625- to 0.125-mm-size fraction, 100 grains counted per slide. Middle of 

field number corresponds to station number in fig. 2. Tr., trace]

Field No. 0)

O

c 

N

D

e

QJ 

I

0

iH 'P.

w

"cS

p,

JU

tf

E E

X 

g 

£

Western facies (Pinyon Conglomerate)

P-53-h/t...... ............

54-h/t..................

...87

...92

Average... ...... .89.5

5 

6

5.5

6 

1

3.5

0 

0

0

0

1

.5

0 

0

0

1 

Tr.

.5

0 

0

0

0 

0

0

1

0

.5

Northern facies (Harebell Formation and Pinyon Conglomerate)

H-15-h.....................

17-h.....................

34-hl...................

34-h2... ................

35-h/t..................

41-t/h....... ...........

P-50-h.....................

H-77-t/h2.. ..............

78-t/h.................

Average........

...39

...42

...49

...91

...62

..30

...62

...58

...52

.. 53.9

9 

31 

27 

4 

26

9 

13 

15 

15

16.6

7 

2 

17 

3 

6

1

10 

8 

5

6.6

41 

16 

3 

2 

5

21 

9

8 

21

14.0

Southern facies (Pinyon

P-4-h...... .................

4-t....... .................

64-t/h..................

95-h/t.. ................

95-h/tl......... .......

Average........

...55

...43

...25

...42.4

17 

11

2 

6 

4

8.0

6 

10 

Tr. 

5 

1

4.4

16 

20 

18 

15 

9

15.6

4 

5 

3 

0

1

0 

2 

4 

2

2.3

0 

3 

0 

0 

0

0 

4 

6 

4

1.9

0 

0 

1 

0 

0

0 

0 

0

1

.2

0 

0 

Tr. 

0 

0

7 

0 

1 

0

.9

0 

Tr. 

0 

0 

0

30 

0 

0 

0

3.3

0

1 

0 

0 

0

2 

0 

0 

0

.3

Conglomerate)

0 

7 

Tr. 

4 

4

3.0

0 

3 

0 

2

1

1.2

0 

Tr. 

0

1 

0

.2

4 

3 

3 

5 

4

3.8

0 

3 

21 

29 

52

21.0

2 

Tr. 

0 

0 

0

.4

"Colorless and light-blue-green amphibole. 

6Pleochroic brown amphibole.

Formation along the Gros Ventre drainage (Love, 

1956b). Crossbedding is common; some ripple marks 

and ripple. cross-lamination are also present. Mud 

chips and probable shrinkage cracks were seen at a 

few localities. PETROGRAPHY

Most of the sandstones consist of poorly rounded, 

moderately sorted sand set in either calcite cement 

or fine-grained argillic matrix. The sandstones are 

of two types: nontuffaceous and tuffaceous (figs. 

17 and 18). The nontuffaceous sandstones are similar 

in texture and composition to the sandstone matrix 

of the conglomerate fades, containing as they do 

abundant angular quartz, feldspar, altered rock 

fragments, and chert, and lesser amounts of quartzite, mica, and heavy minerals (table 8). The tuffaceous sandstones are very distinctive under the 

microscope. They contain abundant euhedral quartz, 

zoned plagioclase, and brown biotite, and lesser 

amounts of volcanic rock fragments, altered rock 

fragments, chert, quartzite, and heavy minerals 

(fig. VIA and B). Mixing with nontuffaceous detritus 

is obvious in many of the tuffaceous sandstones (fig. 

17A and B). Chemical analyses of a few samples 

show that the tuffaceous sandstones have higher 

Na20/KoO and Al2Q3/Si02 ratios than their nontuffaceous counterparts (table 9) ; the chemical 

differences probably reflect the larger quantity of 

plagioclase found in the tuffaceous sandstones.

TABLE 8. Modal composition (in percent) of the tuffaceous and nontuffaceous sandstones of the lower member of the

Harebell Formation

[300 grains counted per slide. Field numbers correspond to station numbers in fig. 2. Leaders (......) indicate not present]

Field No. Quartz Potassium 

feldspar

r>io i Volcanic rock Altered Plagioclase fragments fragments Chert Quartzite Mica1

Fine-grained Calcite 

altered matrix cement

Heavy 

minerals

Tuffaceous sandstone

W-368 

377 

378 

379 

380. 

382 

383 

384 

H-36-t/h 

39-t3 ........

41-t2 ......

41-t3 ......

251-t/h ...

261-tl ......

262-t2 ....

..... 11.0

..... 23.3

..... 15.7

..... 21.7

..... 23.3

..... 29.0

..... 31.6

..... 16.3

..... 38.3

..... 20.3

..... 35.0

..... 21.6

..... 25.0

...... 27.7

...... 44.0

2.7 

1.7 

3.3 

2.3 

4.0

1.7

.7 

1.7

2.7 

5.7

2.3 

1.7 

2.7 

1.0 

1.3

25.0 

27.3

23.7 

22.0 

49.3

39.0 

52.0 

31.7 

35.7 

11.7

30.3 

14.0 

42.3 

42.3 

31.3

6.7 

13.0 

15.7 

1.3 

2.7

1.7 

1.0 

1.0

'2.7

1.7

1.0 

.3

6.0 

6.7 

6.7 

5.7 

2.3

6.0 

2.7 

3.7 

4.3 

11.7

5.0 

5.3 

3.0 

4.7 

3.7

0.7 

1.3 

3.3 

4.3 

1.3

.3

"2.0 

4.0

"£7 

.3

"".3

1.0 

1.7

4.0 

.3

10.3 

1.7 

1.0 

1.7 

2.0

T.b

1.0

6.7 

1.7 

2.7 

.3 

5.0

3.3 

2.3 

12.3

2.7 

1.3

4.3 

.3 

4.3 

2.0 

1.3

232.0

21.0 

24.0 

241.7 

212.0

8.7 

7.0 

30.0 

12.7

16.3 

.3 

20.7 

19.7 

1.0

6.3 

2.0

""3

40".0

- 

16.0

2.0 

.3 

1.0 

.3

.3 

.3

2.3"7

6.7 

6.7

.7 

.7

Nontuffaceous sandstone

L66-5-5 .......

5-24A 

H-52-t/h2 .

244-tl 

246-t2 ....

253-t/h .

257-t 

261-t ..... .

280-t ......

...... 23.0

..... 50.6

..... 50.3

...... 28.3

..... 48.4

...... 39.0

...... 42.6

...... 49.7

...... 36.0

3.0 

3.7 

1.7 

.7 

1.3

3.0 

4.7 

2.3 

5.7

6.7 

1.3 

3.7 

1.3 

2.3

5.7 

7.7 

9.7 

7.3

0.3 

".3

9.0 

8.7 

6.0 

8.0 

11.7

7.3 

5.3 

8.7 

7.3

3.0 

15.3 

12.7

2.0

7.7

7.0 

1.7 

11.3

2.7

3.3 

4.0 

4.3

.7

2.0

.7 

2.7 

.3

2.7 

.3 

.3

.7 

.7

3.0

.7

"L7

20!7 

6.0 

20.7

24.7 

15.3 

14.7 

38.0

48.3

52"3

36.0

8.0 

21.3 

1.0

0.3

"7

.7

.3

lib

lrTuffaceous sandstones have biotite only,

2Includes chert cement.

includes some detrital(?) carbonate.

479-609 O - 72 -
B26 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

QUARTZ, CHERT, QUARTZITE 110"30'

FELDSPAR UNSTABLE ROCK 

FRAGMENTS 

PLUS MICA 

EXPLANATION

Distribution of sandstone in 

Harebell Formation

Nontuffaceous sandstone

Tuffaceous sandstone

FIGURE 18. Composition of clastic constituents and distribution of tuffaceous and nontuffaceous sandstones in the 

lower member of the Harebell Formation.

FIGURE 17. Photomicrographs of sandstone and tuffaceous 

rocks in the lower member of the Harebell Formation. A, 

Calcite-cemented tuffaceous arenite with admixed nonvolcanic detritus; station 39 on Pilgrim Creek; crossed nicols. 

B, Calcite-cemented coarse-grained tuffaceous arenite with 

quartz euhedrons, plagioclase with oscillatory zoning, and

quartzite fragment; station 262 on the south slope of Whetstone Mountain; crossed nicols. C, Crystal tuff composed 

of quartz and plagioclase euhedrons cemented by chert; 

type section of the Harebell, station W379 in Snake River 

Canyon; crossed nicols. qz, quartzite; Q, quartz; P, plagioclase.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B27

TABLE 9. Rapid rock analyses (in percent) of nontuffaceous and tuffaceous sandstones from the lower member of the

Harebell Formation

[Middle of field number corresponds to station number in fig. 2. Analysts : Leonard Shapiro, P. L. D. Elmore, G. W. Chloe, H. Smith, J. L. Glenn, and

Lowell Artis]

Nontuffaceous sandstone

Sample No.......... .........................

SiO2 -~ ----- ~

AfeOa 

Fe2 O3

FeO

MgO - .- 

CaO ... ..... ---

Na->0 ........... ........

K2O .........

H2O- .... -- -- ...... -

H2 0+ ...... .. ..... ......

TiO2 .... ........

P2 05 ... ................._.....

MnO ...... ......

CO2-- ..... .......

Sum.. _ _....__

...................... i

...-... 43.6

................. 5.5

................. .73

................. .88

................. .90

................. 24.1

................. 1.1

................. 1.4

................. .38

................. 1.3

................. .27

................ .17

................. .41

................. 19.1

 . 100

2

84.5 

7.1 

.44 

.28 

.70 

1.5 

.34 

1.2 

.74 

1.3 

.24 

.09 

.00 

1.2

100

3

77.8 

8.2 

1.2 

.72 

1.1 

2.2 

1.0 

1.9 

1.6 

1.9 

.35 

.09 

.00 

1.1

99

4

81.5 

7.1 

1.2 

.56 

.93 

.89 

.89 

1.6 

1.4 

2.7 

.35 

.09 

.04 

.54

100

5

73.5 

8.7 

4.0 

3.2 

1.8 

.81 

.85 

1.7 

.93 

3.6 

.59 

.14 

.05 

.17

100

6

73.3 

14.4 

1.4 

.44 

.60 

3.3 

2.6 

1.8 

.67 

.93 

.33 

.05 

.02 

.08

100

Tuffaceous sandstone

7

48.7

8.3 

1.1 

.88 

.90 

18.7 

1.6 

1.6 

.82 

1.6 

.47 

.09 

.67 

14.5

100

8

63.3 

13.7 

4.5 

2.7 

2.5 

5.0 

2.7 

1.0 

1.7 

.80 

1.8 

.28 

.06 

.05

100

9

67.7 

15.0 

3.5 

1.3 

1.7 

2.6 

3.3 

1.5 

.68 

1.7 

.64 

.13 

.07 

.08

100

10

64.2 

10.8 

.83 

.52 

.46 

10.6 

2.2 

1.1 

.54 

2.1 

.26 

.04 

.17 

6.1

100

Sample 

No.

Field 

No.

..L66-5-5

Description

Calcite-cemented lithic arenite. 

Subfeldspathic wacke. 

Lithic wacke. 

Feldspathic wacke. 

Do.

SAMPLE DESCRIPTIONS

Sample 

No.

Field 

No.

All the tuffaceous sandstones studied occur in the 

lower member of the Harebell Formation at or below 

the base of the northern conglomerate facies (fig. 

18), whereas nontuffaceous sandstones are interbedded with both the northern and the southern 

conglomerate facies and also occur below both of the 

facies. Thin sections, supplied by J. D. Love, from 

the lower part of the type Harebell section along 

the south edge of Yellowstone National Park are all 

of tuffaceous sandstone. One sample (fig. 17C) from 

the type Harebell contains numerous perfect quartz 

and plagioclase euhedrons in a silicified matrix and 

might more appropriately be termed a crystal tuff. 

Quartz euhedrons in the tuffaceous sandstones 

show straight extinction and commonly exhibit resorption cavities identical with those seen in the 

quartz phenocrysts of many volcanic flows. Both 

quartz with straight extinction (and angular outlines) and quartz with undulose extinction are common in the nontuffaceous sandstones, an observation 

which raises the possibility of an unrecognized volcanic contribution to them also. Feldspars in the 

nontuffaceous sandstones are orthoclase, microcline, 

perthite, and plagioclase; plagioclase is by far the 

most abundant feldspar in the tuffaceous sandstones. The volcanic plagioclase consists of both fresh 

and altered grains, and many whole and broken 

euhedrons exhibit either normal or oscillatory zoning. Most of the plagioclase shows polysynthetic 

albite twinning, and determinations by the MichelLevy method indicate calcic compositions as high as 

An54 . Most of the volcanic rock fragments are 

distinguished by small laths and microlites of plagioDescription

Tuffaceous wacke. 

Calcite-cemented tuffaceous arenite. 

Tuffaceous wacke.

Do. 

Calcite-cemented tuffaceous arenite.

clase set in an altered matrix. Altered rock fragments, chert grains composed of microcrystalline and 

chalcedonic quartz and quartzite fragments are common in both tuffaceous and nontuffaceous sandstones, 

emphasizing the mixing of detritus from different 

sources. Large brown biotite flakes are abundant in 

some tuffaceous sandstones, whereas both muscovite 

and biotite are present in nontuffaceous sandstones.

Sparry calcite is the most common cement in both 

tuffaceous and nontuffaceous sandstones. In sandstones where calcite is minimal, a brown fine-grained 

matrix consisting of clay minerals, microcrystalline 

quartz, disseminated opaque minerals, and possibly 

other unidentified minerals is abundant.

Heavy-mineral separates of the 0.0625- to 0.125- 

mm fraction of 11 selected sandstone samples showed 

wide variation (table 10). Three tuffaceous sandstone samples contain floods of angular grains of 

either dark-brown clinoamphibole or spTiene and 

lesser amounts of garnet, zircon, and tourmaline. 

The eight nontuffaceous sandstone samples examined 

contain mainly garnet, zircon, and tourmaline, and 

only small amounts of sphene and amphibole. As in 

the conglomerate matrix, both nontuffaceous and 

tuffaceous sandstones contain rounded and euhedral 

zircon and tourmaline. Tourmaline, including the 

only grains observed of the variety indicolite, is 

especially abundant in the Harebell sandstones of 

the Gros Ventre drainage.

MINOR LITHOLOGIES

Thin shale and claystone beds occur both in the 

conglomerate facies and, with coal and sparse lime-
B28 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 19. Imbrication in the Pinyon Conglomerate along the South Fork of Fish Creek. Sandstone 

lens defines bedding; current flowed from right to left. Note pick for scale, lower right.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B29

stone beds, in the sandstone fades. X-ray diffraction 

patterns of six shale and claystone samples showed 

quartz (abundant in all samples), montmorillonite(?) (all samples), chlorite(?) (five samples), 

biotite (three samples), and calcite (one sample). 

Three limestone samples examined in thin section 

consist of fine-grained dusty calcite. Silt-sized quartz 

grains and tiny microflakes of biotite were observed 

in the limestone samples. Insoluble residues of four 

limestone samples ranged from 15 to 51 percent, 

and X-ray diffraction patterns of the residues 

showed quartz (all samples), biotite (all samples), 

chlorite(?) (three samples), and montmorillonite(?) (one sample).

TABLE 10. Nonopaque heavy minerals (in percent) in sandstones of the Harebell Formation

[0.0625- to 0.125-mm-size fraction, 100 grains counted per slide. Middle of 

held number corresponds to station number in fig. 2. Tr., trace]

Field No.

Tuffaceous sandstones in lower member north of Spread Creek

H-36-t/h....

251-t/h..

Average......

.... 3

.... 1

.... 1

.... 1.7

Tr. 

5

0

1.7

14 

3 

24

13.7

82 

8 

73

54.3

0 

0 

0

0

0 

0 

0

0

0 

0 

0

0

Tr.

2 

0

.7

1 

81 

2

28.0

0 

0 

0

0

Nontuffaceous sandstones in lower member north of Spread.Creek

H-27-h........

52-t/h....

70-20......

Average......

.....73

.... 18

....82

....35

....52

5

65 

12 

54

34

6 

14 

4 

10

8.5

15

1 

0

1

4.3

Tr.

2 

0 

0

.5

Tr.

0 

0 

0

0

1

0 

2 

0

.8

0 

0 

0 

0

0

0

0 

0 

0

0

0 

Tr. 

0 

0

0

Nontuffaceous sandstones in the Gros Ventre drainage

H-9-t..........

26-t/h.....

24-tl.......

Average......

.....42

..... 4

.....15

.....15.5

8 

86 

45 

55

48.5

C 32

C 50 

"18

26.8

9 

3

1 

8

5.3

4 

0 

0 

2

1.5

0 

0 

0 

0

0

4 

0 

3 

0

1.8

1

0 

0 

2

.8

0 

0 

0 

0

0

0 

0 

0 

0

0

"Colorless and light-blue-green amphibole.

6Pleochroic brown amphibole.

"Tourmaline includes small amounts of the variety indicolite.

SEDIMENTARY STRUCTURES AND

PALEOCURREN TS

IMBRICATION

DESCRIPTION

Imbrication, or shingling, is defined by the subparallel arrangement of oblate, or flat, stones inclined to the bedding (fig. 19). In the Harebell 

Formation and the Pinyon Conglomerate the stones 

are inclined upstream, as indicated by crossbedding 

and by regional variation in roundstone size. Recognition and measurement of imbrication depend first 

on precise determination of the bedding attitude as 

a reference plane. The bedding attitude is usually 

defined by sand lenses and by variations in sorting 

and in roundstone size. If the bedding is inclined, 

as it is in most places, the imbrication orientation 

must be restored to its original position by rotating 

the bedding plane to horizontal. Imbrication orientation was used for paleocurrent studies in the

conglomerates because imbrication is widespread and 

well defined and because generally it is the only 

paleocurrent indicator present. Although imbrication 

orientation can be roughly estimated for a quick 

knowledge of paleocurrent direction, I chose to determine the orientation by measuring the fabric of 

stones in each outcrop. This is time consuming, but 

it does provide statistical information necessary for 

precise description of imbrication and for comparisons leading to environmental interpretations.

MEASUREMENT AND STATISTICAL ANALYSIS

Each determination was made by measuring the 

c-axis orientation (both azimuth and inclination) of 

50 oblate stones in part of an outcrop, usually 

limited to several square feet. Generally at least two 

determinations of 50 c-axis orientations each were 

made at each outcrop. Measurement was facilitated 

by orienting a pencil perpendicular to the ab plane 

of each stone and measuring the pencil orientation. 

Orientations measured in inclined strata were restored to their original position by rotating the 

bedding plane to horizontal (computer program of 

Mclntyre, 1963). The resulting orientations of 50 

c-axes may be plotted on a stereographic projection 

(fig. 20) but are more easily analyzed statistically 

by computer.

270

180

FIGURE 20. Lower hemisphere stereographic projection 

of 50 oaxis orientations of oblate roundstones. Calculated statistics based on the spherical normal 

distribution model are: 5 = 252.5°; ^ = 60.4°; 7? = 40.8 

(81.6 percent); k = 5.3; c0.95 = 9.6°; x2w = 20.7 with 13 

degrees of freedom; x2(x> = 23.3 with 15 degrees of 

freedom, "x" marks position of vector mean; the 

dashed circle outlines r0.95, the spherical circle of 

confidence (95-percent level).
B30 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

TABLE 11. Imbrication statistics at stations in the western fades (Pinyon Conglomerate), the northern fades (Harebell 

Formation and Pinyon Conglomerate), and the southern fades (Pinyon Conglomerate)

[Each determination was calculated by averaging 50 c-axis orientations. Stations are located in fig. 2. 5=vector mean azimuth; $=vector mean inclination; /?=vector 

magnitude; c0 .<«=radius of spherical circle of confidence; A=an indicator of dispersion; xz<*i=chi square for angular dispersion about the vector mean; rff=degrees of 

freedom for x2i*>; and x2«>=chi square for azimuthal dispersion about the vector mean (with 15 degrees of freedom)]

Station 

No.

v o> i«> h &c 0> a

"w l> "»

0> = O 0) 0) 3 0> m g> 

1-Q.fc. ^"a 3 Sit. '^M * 8-3 °'M 

3 5 > 3 k x2<*> df

X2(X) 

(15df)

Western facies (Pinyon Conglomerate)

53...............

54A............

54B............

56...............

..... 147.9

...... 160.2

...... 139.6

..... 121.7

Northern facies

15...............

16...............

17B............

34A.. ..........

34B............

35...............

37...............

38...............

39...............

40...............

41. ..............

43...............

44A. ......... ..

44B...... ......

46...............

47...............

49...............

50.... ........ ... 

51...............

52...............

57...............

58...............

59... ............

60...............

61..... ..........

62A............

62B.... .........

73.. ......... .....

75................

76................

77 A.... ......... 

77B....... ......

78A............ 

78B.. ...........

247A.. .......... 

247B. ............

248A. ............

256A. ...........

256B.............

256C.... .........

259A.............

259B. ............

259C..... ........

260................

265................

268A... .........

268C............. ofic'n

269A.... ......... 

269B.. ...........

270A

271A.... ........

271B... ..........

272A. ............

272B..... ........

273................

274A...... .

274B... ..........

274C.. ...........

275A. ............

275B.... ........ 

277A. ........ ...

97'7'R

278..............

..... 41.3

84.6 

105.9

90.4 

..... 57.9

..... 39.5

..... 36.0

...... 55.6

63.3

..... 88.1

..... 71.7

..... 105.6

...... 89.4

..... 71.0

...... 92.3

71.1

...... 91.0

92.9

79, Q

..... 322.0

..... 111.9

..... 111.3

..... 142.6

..... 113.7

..... 83.0

..... 34.2

.... 136.6

...... 95.6

..... 131.2

..... 82.9

90.4 

...... 39.7

324.3 

..... 154.8

32.3 

.... 44.0

1 C Q

1 on Q

..... 96.3

..... 104.0

.... 110.6

.... 85.5

..... 46.5

..... 116.6

69.7

46.2 

67.5

118.1 

..... 111.3

84.4

.... 89.7

m l

01 Q

.... 56.7

..... 59.1

.... 72.2

..... 109.0

..... 86.0

.... 105.6

..... 52.1

..... 41.7

37.8

..... 111.2

47.0 37.8 11.5 4.0 8.1 

59.6 43.5 7.8 7.6 6.9 

68.8 36.4 12.4 3.6 24.8 

68.4 43.5 7.8 7.6 16.8

15 

10 

15 

10

20.5 

17.6 

24.8 

21.2

(Pinyon Conglomerate and Harebell Formation)

61.5 40.2 10.0 5.0 17.1 

55.4 40.6 9.7 5.2 19.4 

53.5 45.5 6.3 11.0 18.0 

54.4 44.4 7.1 8.8 16.2 

58.8 38.4 11.1 4.2 27.3

58.8 43.8 7.5 8.0 13.2 

63.1 41.1 9.4 5.5 24.5 

61.1 40.2 10.0 5.0 16.8 

44.2 42.3 8.6 6.4 6.8 

75.9 44.0 7.4 8.2 7.3

64.4 42.0 8.8 6.1 21.3 

62.5 38.1 11.3 4.1 17.3 

49.4 40.2 10.0 5.0 17.5 

60.6 42.3 8.6 6.3 16.8 

57.3 40.7 9.7 5.2 19.4

59.3 39.5 10.4 4.6 17.0 

52.7 45.6 6.2 11.3 1.8 

64.1 43.4 7.8 7.5 12.0 

67.4 43.3 7.9 7.4 12.7 

57.5 39.2 10.6 4.5 6.5

52.2 40.2 10.0 5.0 19.1 

81.4 43.9 7.5 8.0 13.3 

52.3 46.0 5.9 12.4 19.0 

58.9 42.4 8.5 6.5 30.8 

57.9 43.4 7.9 7.4 8.4

55.9 42.2 8.7 6.3 38.1 

52.2 43.1 8.0 7.2 9.0 

69.0 43.8 7.6 7.9 31.0 

54.0 41.8 8.9 6.0 25.9 

67.7 44.8 6.8 9.5 9.3

55.2 43.9 7.5 8.0 6.3 

52.3 45.7 6.1 11.5 13.3 

72.9 40.1 10.0 4.9 30.6 

74.0 38.7 10.9 4.3 15.4 

80.4 41.3 9.2 5.6 16.7

74.3 41.9 8.9 6.0 8.5 

71.0 39.1 10.7 4.5 27.3 

57.3 41.6 9.1 5.8 29.0 

78.6 43.8 7.6 7.9 16.3 

68.6 43.9 7.5 8.0 12.0

66.2 44.5 7.1 8.9 28.2 

67.8 43.8 7.6 7.9 17.1 

63.8 46.2 5.7 13.1 3.8 

51.4 42.9 8.2 6.9 11.6 

53.1 42.8 8.3 6.8 8.5

50.5 43.4 7.8 7.5 20.1 

75.4 44.6 7.0 9.2 16.3 

64.3 41.0 9.5 5.4 33.5 

56.5 43.3 7.9 7.3 7.3 

54.6 43.6 7.7 7.6 8.9

60.7 45.1 6.6 10.0 11.9 

59.3 45.4 6.4 10.8 16.4 

67.5 42.2 8.7 6.2 19.3 

73.9 43.0 8.1 7.0 7.8 

61.5 43.0 8.2 7.0 13.6

60.0 45.7 6.2 11.5 10.2 

61.8 42.5 8.5 6.5 14.5 

58.2 43.8 7.6 7.9 25.1 

54.3 45.0 6.7 9.8 4.4 

58.2 44.9 6.8 9.7 19.9

66.3 45.3 6.5 10.4 16.8 

60.8 43.6 7.7 7.7 7.5 

52.8 43.9 7.5 8.0 24.3 

53.3 42.6 8.4 6.7 13.0 

65.0 42.0 8.8 6.1 27.0

59.1 44.4 7.2 8.7 11.0 

61.3 44.7 6.9 9.3 10.9 

52.6 43.6 7.7 7.7 23.9 

54.7 42.5 8.5 6.5 17.6 

63.9 45.1 6.6 10.0 25.2

13 

13 

7 

10 

14

8 

12 

13 

11 

10

12 

14 

13 

12 

12

14 

6 

11 

10 

14

13 

10 

8 

11 

11

12 

11 

10 

12 

9

9 

8 

13 

14 

11

12 

14 

12 

9 

10

10 

10 

6 

11 

11

11 

9 

13 

11 

10

9 

9 

12 

11 

10

8 

11 

10 

9 

9

8 

10 

10 

11 

12

10 

9 

10 

11 

9

18.3 

17.6 

19.0 

24.8 

13.3

16.9 

43.4 

6.8 

17.6 

15.4

8.2 

15.4 

17.6 

21.2 

24.0

16.9 

57.8 

11.8 

16.1 

13.3

17.6 

11.8 

21.9 

29.8 

13.3

21.2 

8.2 

16.9 

25.5 

26.2

18.3 

6.8 

16.9 

19.0 

14.7

16.1 

15.4 

19.0 

7.5 

21.2

26.9 

31.2 

16.9 

16.1 

25.5

13.3 

16.1 

17.6 

12.6 

17.6

14.7 

20.5 

29.8 

16.9 

19.0

14.0 

24.0 

9.0 

12.6 

39.8

22.6 

18.3 

16.9 

14.7 

21.2

9.0 

21.2 

25.5 

23.3 

13.3

Southern facies (Pinyon Conglomerate)

1................ "

2A....... ..

2B...... ....

4........... ..

9...............

..... 234.4

..... 239.6

..... 221.3

..... 199.0

..... 168.4

66.2 44.3 7.2 8.6 12.4 

71.6 46.6 5.4 14.6 28.8 

78.0 43.7 7.6 7.8 43.8 

67.2 45.2 6.6 10.2 14.5 

84.7 41.6 9.1 5.8 13.6

10 

7 

10 

9 

12

12.6 

33.4 

14.7 

22.6 

18.3

Station 

No.

~x

«

01 '*&01

s

 » v 

$ Si? i-e-h. ec"o2 1 |>*

Southern facies (Pinyon

10A. .........

10B..........

11A..........

11... ..........

12.............

14............. 

21.... ........ .

22............. 

26A..........

26B

64A..........

64B..........

71A..........

71B..........

71C..........

79 A

72B..........

07 A

Q7"R

88A. .........

88B..........

89A.. ........

QnT>

90A.... ......

90B. .........

92A..........

92B.... .......

93.............

95A..........

95B..........

96A..........

96C.... .......

97 A.......... Q7"R

172A... .......

173A.. ........ 

173B. ..........

181A..........

181B.. ...... ...

183A. .........

183B. ..........

183C... ........

185A..........

185B. ..........

189A.... ......

189B..........

189C..... ......

191A..........

191B........... 

193A.. ........ 

193B...........

194.............. 

195...... ...... .

203..... ........

204A..........

204B... .......

206A. .........

212A

212B. ..........

213A... ....... 

213B. ..........

214B...........

215A... .......

215B...........

91 Q"R

222A

99Q A

223B...........

....... 194.8

........ 198.2

....... 252.5

....... 246.4

149.1 

....... 290.3

16.6 

....... 91.9

. 155.9 

....... 150.9

........ 133.2

....... 148.0

........ 165.9

........ 192.1

....... 130.1

........ 186.5

109.0

....... 131.4

89.6

124.8 

204.2

....... 53.7

........ 194.0

..... 167.4

....... 152.2

....... 180.9

....... 201.3

....... 202.8

1 7Q 9

....... 196.4

....... 167.2

....... 163.0

173.1

.. 176.3 

212.8

....... 131.1

...... 102.0

....... 142.7

........ 116.4

....... 145.5

..... 184.5

... 126.5

....... 115.8

........ 169.0

....... 233.8

. . 139.9

187.8 

170.2 

....... 162.7

132.7 

....... 171.9

212.6

....... 192.7

........ 175.9

....... 116.0

...... 154.0

....... 50.2

....... 115.4

....... 135.3

....... 156.9

174.4

....... 80.2

. .. 250.1

262.2

....... 159.0

....... 148.0

....... 113.4

1 1 9 fi

........ 149.5

....... 182.6

59.7 43.4 

60.6 42.5 

60.4 40.8 

46.2 43.7 

64.1 41.9

80.8 40.3 

67.0 44.2 

65.9 40.2 

69.4 35.6 

73.7 43.6

62.3 40.5 

52.1 46.2 

48.9 42.5 

53.4 45.4 

54.1 43.2

63.3 39.8 

58.2 43.5 

68.2 45.4 

66.4 44.0 

56.7 40.1

53.4 44.4 

59.6 44.5 

61.7 37.9 

68.3 43.0 

49.8 44.8

56.4 43.2 

59.0 42.9 

50.6 43.1 

60.0 42.1 

57.9 45.2

64.7 43.6 

59.4 45.6 

56.4 44.5 

52.7 43.7 

53.0 43.6

59.4 43.0 

72.1 42.0 

60.8 45.4 

62.8 42.7 

58.4 44.4

58.8 42.6 

55.6 41.0 

60.8 42.8 

66.7 41.7 

60.3 43.8

69.4 44.0 

56.1 42.1 

62.4 39.3 

60.9 40.8 

65.3 39.3

61.5 41.8 

57.7 42.5 

52.7 41.8 

72.1 40.9 

51.1 43.3

61.6 42.0 

67.4 45.9 

56.6 43.3 

62.8 43.5 

67.9 41.8

68.3 40.2 

74.0 42.2 

58.6 42.8 

53.0 40.3 

61.9 42.3

61.7 38.3 

55.6 42.5 

73.8 44.1 

50.9 41.8 

65.4 42.9 

70.1 38.2

52.2 45.5 

61.5 44.3 

66.6 43.3 

68.8 42.6 

66.7 45.4 

65.6 45.2

Co.95

(degrees)

k X2(i)

X2w 

df (I5df)

Conglomerate ) Continued

7.9 

8.5 

9.6 

7.7 

8.9

9.9 

7.3 

9.9 

12.9

7.7

9.8 

5.7 

8.5 

6.4 

8.0

10.2 

7.8 

6.4 

7.5 

10.0

7.1 

7.0 

11.5 

8.1 

6.9

8.0 

8.2 

8.0 

8.7 

6.6

7.7 

6.2 

7.1

7.7 

7.7

8.1 

8.8 

6.4 

8.4 

7.1

8.4 

9.4 

8.3 

9.0 

7.6

7.4 

8.7 

10.5 

9.6 

10.6

8.9 

8.5 

8.9 

9.5 

7.9

8.8 

6.0 

7.9 

7.8 

9.0

10.0 

8.6 

8.3 

9.9 

8.6

11.2

8.5 

7.4 

8.9 

8.2 

11.2

6.3 

7.2 

7.9 

8.4 

6.4 

6.6

7.4 

6.5 

5.3 

7.7 

6.0

5.0 

8.4 

5.0 

3.4

7.7

5.1 

13.0 

6.5 

10.7

7.2

4.8 

7.6 

10.7 

8.1 

4.9

8.8 

9.0 

4.0 

7.0 

9.4

7.2 

6.9 

7.1 

6.2 

10.2

7.7 

11.3 

8.9 

7.8 

7.7

7.0 

6.1 

10.8 

6.7 

8.8

6.6 

5.4 

6.8 

5.9 

7.9

8.2 

6.2 

4.6 

5.3 

4.5

6.0 

6.5 

6.0 

5.4 

7.3

6.1 

12.0 

7.3 

7.6 

5.9

5.0 

6.3 

6.8 

5.0 

6.4

4.2 

6.5 

8.3 

6.0 

6.9 

4.1

11.0 

8.6 

7.4 

6.6 

10.6 

10.2

11.5 

22.0 

20.7 

8.7 

10.0

26.0 

18.0 

14.3 

18.9 

6.5

27.2 

10.9 

17.9 

14.3 

10.4

21.0 

7.0 

11.0 

39.1 

15.1

14.7 

13.7 

22.5 

20.7 

6.6

14.1 

12.0 

7.1 

10.4 

20.3

12.1 

9.6 

8.7 

11.1 

5.3

20.0 

8.8 

8.2 

9.6 

10.8

28.3 

15.3 

19.8 

15.3 

5.3

15.8 

15.9 

9.1 

18.6 

20.0

9.3 

17.8 

39.1 

14.2 

17.0

14.4 

8.7 

19.3 

17.6 

7.9

24.7 

14.0 

28.3 

33.8 

21.6

10.9 

9.0 

16.5 

22.3 

14.3 

10.1

8.8 

12.2 

31.7 

15.7 

5.8 

8.7

11 16.1 

11 21.2 

13 23.3 

10 14.0 

12 18.3

13 8.2 

10 20.5 

12 20.5 

16 30.5 

10 42.7

13 27.6 

5 68.6 

11 20.5 

9 18.3 

11 26.2

13 10.4 

10 23.3 

7 26.9 

10 15.4 

11 17.6

10 18.3 

10 65.0 

15 34.1 

11 12.6 

9 14.7

11 6.1 

11 16.9 

11 17.6 

12 26.9 

9 19.0

10 16.9

8 14.7 

8 21.9 

10 17.6 

10 17.6

11 19.0 

12 11.8 

9 16.9 

11 14.7 

10 36.3

11 21.2 

12 14.0 

11 24.8 

12 9.7 

10 26.2

10 16.9 

12 19.0 

14 19.0 

13 16.1 

14 14.0

12 20.5 

11 19.7 

12 17.6 

13 11.8 

11 7.5

12 10.4 

8 13.3 

11 9.7 

10 12.6 

12 6.8

13 18.3 

12 15.4 

11 20.5 

13 27.6 

11 22.6

14 11.1 

11 14.7 

10 10.4 

12 14.7 

11 11.8 

14 31.2

8 8.2 

10 9.7 

11 16.1 

11 18.3 

9 15.4 

8 20.5
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B31

Plots of a few determinations suggested that the 

spherical normal distribution (Fisher, 1953) might 

be an appropriate model ; hence, statistical computations for each determination (50 measurements) 

were made utilizing this model. The resulting statistics are given in table 11. Computational details 

were discussed by Andrews and Shimizu (1966), 

McElhinny (1967), Steinmetz (1962), and Watson 

and Irving (1957), and they are summarized in the 

following paragraph.

Each c-axis orientation is expressed as a vector 

with an azimuth 9 (measured in degrees clockwise 

from north) and an inclination </> (measured in 

degrees from horizontal); each may also be expressed as a direction cosine. The sum of the 

direction cosines (X, Y, Z) for each set of n = 50 

vectors is given by

50

.2 cos </> cos 0=Y,

50

.2 cos </> sin 0=X, and

50

.2 sin </>=Z.

The following statistics are defined in terms of 

direction cosines:

(1) R, the magnitude of the vector mean (resultant 

vector), is calculated by

/?=(X2 +Y2 +Z2 ) 1 /2.

The direction cosines of the vector mean are 

X/R, Y/fl, and Z/fl.

(2) 6, the azimuth of the vector mean (and also of 

the interpreted paleocurrent orientation), is 

given by

(3) </>, the inclination of the vector mean, is given by

(4) co.95, the radius of the spherical circle of confidence about the vector mean, is given by

C0.95-COS

(5) k, an indicator of dispersion for the spherical 

normal distribution model, is given by

(6) x2w> the chi-square for angular dispersion of 

50 c-axis orientations about the vector mean, is 

given by

/ -r, vobs; Jexpj)

X

Z=: > =! J 

j=l f

J expj

where

/obs =ob served frequency of >// in the^'th

class, 

/exp.=expected frequency of i// in the^'th

class, and 

p =number of observed 5° classes,

The observed frequency of »//, /)bSj , is calculated 

as follows. First, »//,-, the angular dispersion 

between the vector mean and each c-axis orientation, is calculated by

Y(+(Z//0 Z,

where

X,-, Y,, and Z* =the direction cosines

for each orientation, 

and 

X/fl, Y//?, and Z/ft=the direction cosines

of the vector mean.

The resulting $,- values are summarized into 

p 5° classes to give/)bs .. The expected frequency 

of $, /expj , is calculated by

where

«=50, the number of c-axis orientations,

0=1 cos [(/ 1)-5], and

b=l cos'(/'5)

and where (y-5) and [(/ 1)-5] are the class 

limits. Then df, the number of degrees of freedom, is given by

df=p-l-2

X2w> the chi-square for azimuthal dispersion 

of 50 c-axis orientations about the vector mean, 

is given by

18 (/ob. -/I/18)»

the mth

where

/)bs =observed frequency of x 

class,

n =50, the number of c-axis orientations, 

and

18 =number of observed 20° classes. 

The c axes are rotated (Mclntyre, 1963) so that 

R, the resultant vector, is alined vertically, 

and the new values for x* are determined. The 

Xt are then partitioned into eighteen 20° classes 

(from 0° to 350°) where the observed frequency 

is/obs in class m and the expected frequency is 

always /i/18=50/18=2.78. The number of degrees of freedom (df) is then always 18 3=15.

Chi-square tests for angular dispersion and azimuthal dispersion about the vector mean confirm the 

appropriateness of the spherical normal model. The 

chi-square values for angular dispersion (X2<*>) of 

74.4 percent of the 156 determinations made on the 

conglomerates do not vary significantly (0.05 level) 

from a spherical normal distribution, nor do the chisquare values for azimuthal disperson (x2w) of 84.0 

percent.
B32 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

The consistency of each determination (50 c-axis 

orientations) is shown by the value of R, the vector 

magnitude (fig. 21A). The vector magnitudes of the 

156 determinations in the conglomerates range from 

35 (70 percent) to 47 (94 percent) and average 42.8 

(85.6 percent). The values for R are much larger 

than the significance point (0.05 level) of R=11.4 

calculated by Watson's (1956) method for testing 

randomness of direction; in other words, none of 

the 156 determinations of 50 c-axis orientations each 

used in this study comes close to being randomly 

oriented.

The precision of each determination is measured 

by the radius of the spherical circle of confidence 

and can be calculated from R and from n, the number of c-axis measurements per determination (fig. 

215). For the 156 determinations in the conglomerates, the radii of the circles of confidence (95 

percent) range from 5° to 13° and average 8.3°. 

In other words, both azimuth and inclination of each 

vector mean can be expected to be within ±5° to 

±13° (95-percent confidence).

COMPARISON OF IMBRICATION IN CONGLOMERATES 

WITH THAT IN MODERN STREAMS

Imbrication is well developed in streambeds of 

Jackson Hole, where quartzite roundstones derived 

from the Harebell and Pinyon conglomerates are 

abundant (fig. 22). At each of 24 stations in the 

streambeds, 50 c-axis orientations were measured, 

and the statistics were summarized by use of the 

spherical normal distribution (table 12). The imbriTABLE 12. Imbrication statistics for 24 determinations of 

50 c-axis orientations each in modern streams of Jackson 

Hole

[Each determination_was calculated by averaging 50 c-axis orientations. Stations 

are located in fig. 2.0=vector mean azimuth; <t>= vector mean inclination; /?=vector 

magnitude; c0 .95=radius of spherical circle of confidence; /t=an indicator of 

dispersion; xz<ii=chi square for angular dispersion about the vector mean; d/=degrees of freedom for x2<Ii; and x2 (5>=chi square for azimuthal dispersion about the 

vector mean (with 15 degrees of freedom)]

Station 

No. df (15$)

171..

174..

175..

176..

177..

178..

179.. 

184..

186..

187..

188..... 

198A.. 

198B.. 

199 . 

202A..

202B..

237.....

238..... 

239A.. 

239B..

240..

241..

242..

243..

267.2

279.5

209.9

238.8

189.0

143.4

262.7

11.9

258.4

261.7

214.9

198.8

. 259.3

129.2

125.2

. 169.7

254.5

2.6

357.0

. 16.1

335.2

351.0

308.2

309.9

61.4

68.2

59.9

63.4

59.8

56.7

67.2

62.3

57.5

63.9

60.5

66.1

65.3

52.3

62.5

58.6

61.4

58.3

63.3

66.2

64.8

69.2

59.6

62.7

45.8

43.3

39.8

44.4

44.2

44.9

45.9

42.3

45.2

45.4

44.7

45.5

44.3

43.1

45.4

44.2

45.1

44.2

46.6

44.7

45.4

43.8

44.6

46.0

6.1

7.9

10.2

7.1 

7.3

6.8 

6.0 

8.6 

6.6 

6.4

6.9 

6.3 

7.2 

8.1 

6.4

7.3 

6.6 

7.3 

5.4 

6.9

6.4 

7.5 

7.0 

5.9

11.7 

7.3 

4.8 

8.8 

8.5

9.6

12.1

6.4

10.2

10.6

9.3

10.9

8.6

7.1

10.8

8.4

10.0

8.4

14.4

9.2

10.7

8.0

9.1

12.4

8.8

21.7

14.4

16.1

16.2

5.5

9.5

7.8

29.3

7.8

13.7

5.7

11.1

11.1

10.2

14.8

9.1

14.7

5.5

7.9

6.8 

6.4 

4.7 

9.8

11

13

10

10

11

9

9

9

9

10

11

9

10

9

10

7

9

9

10

11.1

14.0

24.8

15.4

19.0

29.1

15.4

16.1

22.6

16.9

31.9

7.5

16.9

16.9

11.8

16.1

11.8

19.0

17.6

11.8

13.3

10.4

17.6

21.2

30

20

10

0

35

70

< 30

20

10

x = 42.78 

S 2 =4.45 

N=156

40 45 

R (ABSOLUTE VALUE)

80 90

50

100

R (PERCENT)

B

5=8.32° 

§2 = 2.02 

N = 156

10 

co.95, IN DEGREES

15

FIGURE 21. Frequency distribution of the vector magnitudes (R) and of the radii of the spherical circles of 

confidence (co.gg) for 156 determinations consisting of 50 

c-axis orientations each. A, Vector magnitudes; B, radii 

of spherical circles of confidence, x, arithmetic mean; 

s2, variance; N, number of determinations. All determinations are from the Harebell Formation and the Pinyon 

Conglomerate. For a sample of 50 c-axis orientations to 

have a probability of ^0.05 of being drawn from a randomly oriented population, R must be ^11.4 (22.74 percent) .
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B33

FIGURE 22. Imbrication of quartzite roundstones derived from the Pinyon Conglomerate on the North Fork of Fish Creek.

Stream in background flows from left to right.

cation dips upstream at all the stations studied, 

which is in general agreement with the dips observed for other fluvial deposits (PettiJohn, 1957, 

p. 250-251). Hence, the vector mean azimuth for 

c-axis orientations points downstream in all the 

streambeds studied and also in the conglomerates.

The inclinations of c-axis vector means computed 

for imbrication in the Jackson Hole region (fig. 23) 

average 61.6° for conglomerate roundstones and 

62.2° for stream roundstones. These figures correspond to an upstream inclination (ab plane) of about 

28°-29°, the general range for fluvial deposits that 

Cailleux (1945) reported, and they contrast with 

his very low inclinations for marine imbrication. In 

a brief survey of the literature on imbrication, 

Pettijohn (1957, p. 250-251) noted disagreement 

among the findings of Cailleux and those of Krumbein (1939, 1940, 1942; see also calculations of inclination on Krumbein's data by White, 1952). 

Krumbein's imbrication data are difficult to compare 

with those from the Harebell and Pinyon conglomerates because (a) pebble long axes instead of short 

axes were measured at San Gabriel Canyon, Calif. 

(1940), and Arroyo Seco, Calif. (1942), and (b) 

both these deposits and the glacial outwash studied 

(Krumbein, 1939) consisted of poorly sorted and 

poorly rounded stones in comparison with the conglomerates of Jackson Hole. Later studies have 

reported upstream inclinations of 20°-25° (Sedimentary Petrology Seminar, 1965) and 14°-25° 

(Schlee, 1957a) for fluvial gravels, somewhat less 

than the inclination observed in the conglomerates. 

In summary, it seems best to compare the inclination 

of roundstone imbrication in the conglomerates with 

that in modern streams of Jackson Hole, inasmuch 

as the same quartzite stones dominate both. The 

similarity of the degree of roundstone inclination in 

conglomerates to that in streams supports the interpretation of a fluvial environment of deposition for 

the conglomerates.

The variance of c-axis inclinations for roundstones 

is much less in modern streams than in the conglom-
B34 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

25

20

15

10

~1 I CONGLOMERATES

£=61.58° 

s2 =60.12

CONGLOMERATES

£=7.36

s 2 =4.55

AT=156

C/3

O 45

z

2

£ 40

LU

D

35

O

Pi 30

25

20

15

10

STREAMS

£=62.18° 

«2 = 15.84

STREAMS

£=9.52 

S2 =4.42

40 50 60 70 80 90

MEAN ANGLE OF INCLINATION 

IN DEGREES

5 10 

DISPERSION (k)

15

FIGURE 23. Comparison of mean angle of inclination (0) and dispersion (k) of c-axis orientations between 

roundstones from the Harebell Formation and the Pinyon Conglomerate and roundstones from modern 

streams in Jackson Hole. The average of the mean inclination angles for conglomerates is not significantly 

different from that for streams at any acceptable level. The average dispersion for the conglomerates is 

significantly different from that for streams at the 0.01 level, x, arithmetic mean; s2, variance; N, number of determinations.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B35

erates. The difference may result from two factors: 

(a) orientation of stones in the conglomerates may 

be affected by compaction or tectonism, and (b) 

c-axis measurements may be rotated by an incorrect 

amount when bedding is restored to horizontal. Bedding in the conglomerate is difficult to measure 

precisely, and errors in measurement may lead to 

undercompensation or overcompensation when the 

data are rotated, especially if bedding strike and 

imbrication azimuth intersect at a large angle.

Dispersion of orientations in roundstone imbrication in Jackson Hole (fig. 23) is significantly greater 

in the conglomerates (average & 7.4) than in modern streams (average k=9.5). (The computed indicator of dispersion (k) becomes larger as dispersion 

decreases.) The greater dispersion noted for the 

conglomerates may be due to two causes: (a) different original orientation related to differences in size, 

shape, or sorting, and (b) compaction or tectonic 

deformation causing reorientation of the conglomerate stones. The effects of the latter are commonly 

visible in outcrop, but differences in size, shape, or 

sorting between the conglomerate roundstones and 

the stream sediments appear minimal. Therefore 

compaction or tectonic deformation is viewed as the 

most likely explanation for the differences in orientation dispersion.

PALEOCURRENTS

Paleocurrent directions as interpreted from the 

azimuth of the c-axis vector mean for each determination are shown in figure 24. In general, imbrication-orientation data show that paleocurrents flowed 

east-northeasterly (mean direction=78.2°) in the 

northern facies and south-southeasterly (mean directional 63.9°) in the southern f acies. Imbrication 

azimuths in figure 24 likewise define two distinct 

paleocurrent systems: one associated with the northern facies and one with the southern facies. Within 

the northern facies, no differences in imbrication 

orientation are apparent between the Pinyon Conglomerate and the Harebell Formation. The small 

standard deviations of ±42.6° and ±49.6° for the 

northern and southern facies respectively indicate 

that arithmetic averaging of vector azimuths will 

produce reliable approximations in further computations.

Maps of moving-average vector azimuths for the 

northern and southern facies were prepared by computer (fig. 25). The azimuthal data were gridded by 

computing a weighted moving-average direction at 

each grid intersection (grid cell=:2 miles square, 

oriented north-south). Each grid value was computed from the eight nearest vector azimuths by 

weighting each azimuth inversely with respect to its

distance from the grid intersection and then taking 

the arithmetic average of the weighted azimuths. In 

the northern facies this involved subtracting azimuths in the northwest quadrant from 360° and 

changing the sign to negative in order to average 

the data properly with the predominantly east-northeast paleocurrents. The gridded azimuth values were 

then plotted as vectors.

In addition to smoothing the directional data by 

the moving-average method, it was desired to determine what, if any, local trends are present within 

each facies. Generally, more than one imbrication 

determination was made at each station, thus allowing computation of the precision of the station vector 

means. The 152 determinations from both facies are 

readily grouped at two additional levels: 82 stations 

(42 in the northern facies and 40 in the southern 

facies) and two facies (northern and southern). 

Analysis of variance (Krumbein and Graybill, 1965, 

p. 191-221) showed highly significant differences 

between facies, as might be expected, but not between stations (table 13). The largest variance component exists at the facies level, the next largest at 

the determination level, and the smallest at the 

station level (table 13). Comparison of the variance 

component at the determination level with that at 

the station level suggests that a minimum of 10-20 

determinations per station are required to detect 

significant differences between stations. Because only 

about two determinations per station were made, 

the precision of the station vector means is very 

poor, and the moving-average map is not likely to 

show real variation within each facies.

TABLE 13. Analysis of variance and estimates of variance 

components for imbrication azimuths (three-level nested 

design)

[Computed from data in table 11] 

ANALYSIS OF VARIANCE

Level

Total....................................

Between stations

Between determinations 

within stations... ...... ....

Degrees of 

freedom

150

1

80

69

Sum of 

squares

602,810

285,660

187,520

129.630

Mean 

square

285,660.0

2,344.0

1.878.7

F 

value

121.87

1.25

Significance

<0.0001

ESTIMATES OF VARIANCE COMPONENTS

Level Variance component Unit size

Facies... ...........

Station...............

Determination. .

3,771.5

253.6

1,878.7

2

82

151

CROSSBEDDING AND RIPPLE CROSS-LAMINATION

HAREBELL AND PINYON PALEOCURRENTS

In the sandstones of the Harebell Formation and 

the Pinyon Conglomerate, festoon crossbedding is 

common, and ripple cross-lamination is present locally. Crossbedding is not common in the conglomerates but does occur locally in sandstone lenses (fig. 

26). As many measurements as possible (one to 15)
B36 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

. 114 W, 30' R. 113

Mean paleocurrent direction 78.2 

Standard deviation 42.6 

SUMMARY IMBRICATION

DIAGRAM 

ORTHERN FACIES

70 determinations

WESTERN FACIES 15

20

25

PERCENT OF 

DETERMINATIONS:

\ NORTHERN FACIES

SUMMARY IMBRICATIONi 

SOUTHERN FACIES 

82 determination^

PERCENT OF 

DETERMINATIONS

T. 40 N, 

Mean paleocurrent direction 163,9" 

EXPLANATION Standard deviation 49.6

Conglomerate facies 

cp, Pinyon Conglomerate 

ch, Harebell Formation

Area of 

map 

Contact WYOMING

Dashed where inferred

Imbrication azimuth

FIGURE 24. Paleocurrent directions as interpreted from imbrication azimuths in the Harebell Formation and 

the Pinyon Conglomerate. Each arrow is the azimuthal result of 50 c-axis orientations (one determination) .
111-00'

PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B37

R. 114 W. 30' R. 113 W. R. 112 W.

NORTHERN 

T. 47 N. \ v FACIES

Conglomerate facies 

cp, Pinyon Conglomerate 

ch, Harebell Formation

Contact

Dashed where inferred

Direction of imbrication

Moving average

 

Sample station

FIGURE 25. Moving-average directions based on imbrication in the Harebell Formation and the Pinyon Conglomerate.
B38 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 26. Large-scale festoon crossbedding in sandstone lenses near the top of the Pinyon Conglomerate on Purdy Creek,

a tributary to the South Fork of Fish Creek.

were taken at each outcrop to determine paleocurrents in the sandstones and to check conglomerate 

paleocurrents deduced from roundstone imbrication. 

Crossbedding orientations were restored to original 

orientations by rotating the bedding planes to horizontal; vector mean azimuth and vector magnitude 

were computed for each station (fig. 27). Crossbedding dip azimuths in both the northern conglomerate facies (95.4°) and the underlying Harebell 

sandstones (63.8°) were found to be easterly and 

northeasterly, in close agreement with imbrication 

data from the conglomerates. Crossbedding dip azimuths in the southern conglomerate facies are southsoutheasterly (163.5°), also in close agreement with 

imbrication data. Harebell crossbedding in the south 

was too variable and sparse to yield clearly a preferred orientation. Crossbedding orientation confirms 

the upcurrent inclination of imbricated roundstones 

in the conglomerates and agrees well with the paleocurrent directions determined from imbrication 

orientation.

UPPER CRETACEOUS AND PALEOCENE PALEOCURRENTS 

COMPARED

Most of the Harebell and Pinyon paleocurrent 

systems are strongly unidirectional, a feature consistent with fossil evidence for a continental alluvial 

environment. The underlying Upper Cretaceous 

sandstones and shales contain both marine and continental strata, and fossil evidence suggests the proximity of a marine environment for parts of the 

Harebell Formation. Crossbedding orientation in 

strata above and below the Harebell and Pinyon 

south of Buffalo Fork was studied briefly to assess 

marine influence on paleocurrent orientation and to 

determine what, if any, information might be gained 

concerning the source of these sediments. The crossbedding azimuths exhibited two distinct types of 

distribution (fig. 28) : (1) bimodal symmetrical distribution for the mixed marine and continental sandstones (the Bacon Ridge Sandstone, the lenticular 

sandstone and shale sequence, and the Mesaverde 

Formation), and (2) unimodal distribution for the
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS

R. 114 W. 30' R, 113 W. R, 112 W.

B39

IT. 48 N.

^SUMMARY CROSSBEDDING DIAGRAM 

NORTHERN CONGLOMERATE FACIES

arebeiyfdmiation and Pinyon Conglomerate)

Mean paleocurrent'. 

direction 63.8° ':/:: :'. 

Standard-deviation]'; -" ' "." ! 

64.8° v %N-N ">4r'

Mean paleocurrent 

direction 95.4° 

Standard deviation

SUMMARY CROSSBEDDING DIAGRAM

SANDSTONE FACIES (NORTHERN PART)

(Lower member of Harebell Formation)

162 measurements

SUMMARY CROSSBEDDING DIAGRAM

SOUTHERN CONGLOMERATE FACIES

64 measurements

EXPLANATION Mean paleocurrent 

direction 163.5° 

Standard deviation 

74.4°

Conglomerate facies

cp, Pinyon Conglomerate

ch, Harebell Formation

Area of 

map 

WYOMING Sandstone facies

Contact

Dashed wher.e inferred

Single crossbedding reading

15 5

SUMMARY CROSSBEDDING DIAGRAM

SANDSTONE FACIES (SOUTHERN PART)

Harebell Formation

22 measurements

15 MILES

Crossbedding Ripple ' ' ' ' ' ' 

cross-lamination

0 100 VECTOR STRENGTH IN PERCENT

Station vector means and 

number of readings

T. 37 N.

FIGURE 27. Crossbedding orientation in the Harebell Formation and the Pinyon Conglomerate.
B40 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

overlying continental elastics (Harebell Formation, 

Pinyon Conglomerate, and unnamed sandstone and 

clays tone sequence). In the Upper Cretaceous and 

Paleocene of Jackson Hole, a clear distinction is 

apparent between marine-continental and continenPERCENT OF 

DETERMINATIONS

Mean direction 

of crossbedding

Mean direction 

of crossbedding

PERCENT OF 

DETERMINATIONS

PERCENT OF 

DETERMINATIONS

tal paleocurrent systems, and both the Harebell 

Formation and the Pinyon Conglomerate bear the 

stamp of a continental system. The bimodality of 

the continental-marine paleocurrents probably reflects the alternation of these two environments, 

whereas the unimodality of the continental elastics 

reflects fluvial transport from western and northwestern sources.

REGIONAL VARIATION OF QUARTZITE ROUNDSTONE SIZE

Grain size is an indicator of paleostream competency in clastic deposits and is commonly used to 

determine source, paleocurrent directions, and location of paleostreams (Potter and Pettijohn, 1963, p. 

202-205). Grain-size distributions in very coarse 

conglomeratic sediments are impractical to analyze 

in the large numbers necessary to evaluate regional 

trends; therefore, the standard practice of measuring the 10 largest particle sizes at each outcrop was 

applied. In the conglomerate facies, the maximum 

dimension (length) of 973 roundstones was measured (table 14) at a total of 98 stations: three stations in the western facies, 46 in the northern facies, 

and 49 in the southern facies. At each station, the 

10 largest roundstones seen were measured, except 

at two stations where only eight roundstones were 

measured and at one station where only five were 

measured. North of the Teton Range (western facies), maximum quartzite roundstone length (the 

longest of the 10 largest stones for each station) 

ranges from 14 to 50 inches, and the mean maximum 

length (the average length of the 10 largest stones 

for each station) ranges from 12 to 22 inches. In the 

northern facies, maximum quartzite roundstone 

length ranges from 9 to 19 inches, and mean maximum length ranges from 8 to 14 inches. In the 

southern facies, maximum length ranges from 12 to 

21 inches, and mean maximum length ranges from 

9 to 17 inches. Frequency distributions of mean 

maximum lengths show that roundstones are significantly longer in the southern facies than in the 

northern facies (fig. 29; table 15).

Before the regional variation of roundstone length 

was studied further, the data were examined for 

stratigraphic variation. Love (1972, table 1) suggested that roundstones are generally smaller in the 

Harebell Formation than in the Pinyon Conglomerate. If this stratigraphic distinction applies also

FIGURE 28. Paleocurrent directions as interpreted from 

crossbedding orientations in Upper Cretaceous and Paleocene rocks between the Gros Ventre River and Buffalo 

Fork. A, Unnamed sandstone and claystone sequence; 

B, Pinyon Conglomerate; C, Harebell Formation; D, Mesaverde Formation and underlying lenticular sandstone and 

shale sequence; E, Bacon Ridge Sandstone. N, number of 

measurements.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B41

TABLE 14. Length of largest quartzite roundstones at stations in the western fades (Pinyon Conglomerate), the northern 

fades (Harebell Formation and Pinyon Conglomerate), and the southern fades (Pinyon Conglomerate)

[Station localities are shown in fig. 2]

Sta. Lengthl 1 Sta. Length 

No. (in.) || No. (in.)

Sta. Length || Sta. Length 

No. (in.) |l No. (in.)

Western facies 

(Pinyon Conglomerate)

53......... .....11.5

9.0 

12.0 

12.5 

14.0 

12.0 

11.5

53--.....-.10.0

10.0 

14.0 

54.. ......... ...13.0

12.5 

13.0 

11.0

54.. ........ ....12.0

13.0 

12.5 

13.5 

14.0 

12.0 

56........ ...... 50.0

56..............16.0

18.0 

14.0 

15.0 

13.0 

15.0 

15.0

Northern facies 

(Harebell Formation and Pinyon Conglomerate)

15...... ...... ..10.0

10.0 

11.0 

9.0 

9.0

10.0 

10.0 

10.0 

10.0 

10.0

17... ...... .....10.0

11.0 

11.0 

11.0 

10.0

11.0 

11.0 

12.0 

10.0 

12.0

18.............. 7.5

8.0 

8.0 

7.5 

9.5

10.0 

8.0 

8.0 

8.0 

7.5

29.............. 7.0

9.0 

8.0 

8.0

8.0 

8.0 

10.0 

8.0

34..............10.0

10.0 

11.0 

10.0 

10.0

9.0 

10.0 

10.0 

10.0 

11.0

QQ r\ r\

9.0 

11.0 

8.0 

9.0

10.0 

11.0 

9.0 

10.0 

9.0

39.............. 7.5

7.5 

9.0 

9.0 

7.5

8.0 

8.0 

10.0 

7.5 

9.0

40......... .....10.0

11.0

40.............. 9.5

10.0 

12.0 

11.0

13.5 

10.5 

11.0 

12.0

41............. 7.0

8.0 

8.0 

9.0 

9.0

9.0 

7.5 

8.0 

8.0 

9.0

43............. 10.0

12.0 

12.0 

12.0 

10.0

13.0 

10.0 

11.0 

10.0 

12.0

A A Q ft

9.0 

9.0 

9.0 

12.0

10.0 

10.0 

11.0 

9.0 

9.0

45... ....... ....10.0

11.0 

12.0 

12.0 

12.0

13.0 

10.5 

11.0 

12.0 

10.0

9.5 

10.5 

10.0 

9.0

8.0 

9.5 

14.0 

9.0 

9.0

47 12 5

19.0 

12.0 

12.0 

12.0

15.0 

13.0 

15.0 

13.0 

13.0

48... ...........11.0

12.5

48..............11.0

12.0 

13.0

11.0 

10.5 

12.0 

12.0 

11.0

49..... ......... 10.0

10.0 

11.0 

9.0 

9.5

10.0 

11.0 

9.0 

10.0 

10.0

50..............11.0

11.0 

11.0 

10.0 

12.0

10.0 

11.5 

10.0 

11.5 

10.0

51. ............ .10.5

12.0 

13.0 

10.0 

13.5

10.0 

12.0 

10.5 

10.5 

11.0

57............ .10.5

11.0 

12.0 

9.0 

9.5

12.0 

10.0 

11.0 

12.5 

13.0

58..............14.0

11.0 

9.0 

10.0 

10.5

10.5 

11.5 

10.5 

9.0 

9.0

59....... .......15.5

10.0 

10.5 

13.0 

12.0

12.0 

12.0 

12.0 

10.0 

10.0

62.......... ....12.5

12.0 

13.0

62. ........... ..12.0

12.0

12.0 

13.0 

14.0 

18.0 

17.0

73.... ...... ....12.0

10.5 

9.5 

10.0 

9.0

10.0 

11.5 

13.0 

9.5 

10.0

75.. ............ 10.0

9.5 

10.0 

11.0 

11.0

11.5 

10.5 

12.0 

9.5 

9.5

76... ...... .....11.0

9.0 

10.0 

10.0 

11.0

10.0 

9.5 

10.0 

11.0 

12.0

77...... ....... .11.5

11.5 

12.0 

11.5 

13.0

11.0 

11.0 

12 0 

13.5 

13.5

78.............. 9.5

11.0 

12.0 

10.5 

9.5

10.0 

10.0 

9.5 

11.0 

12.0

8.0 

8.5 

10.0 

8.5

7.5 

8.0 

9.0 

10.5 

10.0

10.5 

14.0 

9.5 

ion

Sta. Length 

No. (in.)

Sta. Length] | Sta. Length 

No. (in.) || No. (in.)

Sta. Length 

No. (in.)

Northernn facies Continued

83B ..........10.5

9.5 

12.0 

9.5 

9.5

247. ............ .12.0

10.5 

11.0 

16.0 

17.0

13.0 

12.5 

12.0 

11.5 

11.0

248...... ........11.0

11.0 

11.0 

11.5 

11.0

12.0 

12.0 

11.0 

14.0 

14.0

256. ...... .......10.5

13.0 

10.0 

10.5 

11.0

12.5 

11.0 

11.5 

12.5 

14.0

259.... ...... ....10.0

10.5 

11.0 

11.5 

10.0

10.5 

10.0 

11.5

259..............12.0

12.0 

260.............. 9.5

10.0 

10.5 

9.5 

12.0

9.5 

10.0 

11.0 

10.5 

9.5

265...... ........11.0

11.0 

12.5 

13.5 

12.0

12.0 

11.0 

13.0 

13.0 

12.5

266..... ....... ..14.5

12.0 

12.0 

12.0 

13.0

12.0 

12.5 

15.0 

13.5 

14.0

268... ....... ....12.0

14.0 

14.0 

14.0 

13.0

\4.5 

12.5 

12.0 

12.5 

16.5

269..............12.0

11.5 

16.0 

12.0 

12.0

12.0 

12.5 

12.0 

13.0 

16.0

270... ...... .....12.0

13.0 

13.0 

12.0 

12.0

12.0 

12.0 

12.0 

12.5 

16.0

271..............15.5

12.0 

14.5 

11.5 

13.5

11.5 

13.0 

13.5 

12.0 

12.0

272.... ...... ....15.0

13.0 

13.0 

15.5 

13.0

14.0 

13.5 

15.0 

1S.O 

14.0

274..... ......... 12.5

11.5 

12.5

274..............10.5

11.0

14.0 

12.0 

12.0 

11.5

12.5

31.. .......... ..10.0

11.0 

10.0 

10.0 

11.0

10.0 

9.0 

9.0 

9.0 

9.0

97Q 1 9 ft

12.0 

11.0 

11.0 

12.0

13.0 

12.0 

12.0 

12.5 

12.0

10.0 

10.5 

9.5 

12.0

9.5 

10.0 

11.0 

10.5 

9.5

277..............11.5

10.5 

10.5 

14.0 

13.0

Southern facies 

(Pinyon Conglomerate)

1.............. 8.5

8.5 

10.3 

8.0 

10.7

10.7 

11.5 

12.9 

10.3 

8.5

2..............17.0

13.0 

12.0 

12.0 

12.0

11.0 

11.0 

11.0 

11.0 

11.0

4............ ..16.0

12.0 

11.0 

11.0 

10.0

10.0 

10.0 

10.0 

10.0 

10.0

9.... ..........11.5

9.5 

11.0 

10.0 

12. n

9... ...........10.0

10.5 

9.5 

10.5 

9.5

10..............11.0

10.5 

11.0 

13.0 

12.0

12.0 

12.0 

12.0 

11.0 

12.0

20...... ........10.0

10.0 

11.0 

10.0 

11.0

10.0 

9.0 

12.0 

11.0 

10.0

64.......... ....14.0

14.0 

16.0 

15.5 

14.5

14.0 

15.5 

13.5 

14.5 

15.5

71..............13.5

13.0 

13.5 

15.0 

13.5

13.0 

16.0 

13.0 

13.5 

15.0

72. ....... ......14.5

17.0 

15.0 

14.5 

15.5

16.5 

15.0 

15.0 

14.5 

16.5

87. ........ .....15.0

15.0 

13.5 

13.0 

13.0

13.0 

16.5 

14.0 

14.5 

18.0

88... ...... .....13.5

15.0 

13.0 

13.0 

15.5

15.0

88..............15.0

14.5 

12.5 

13.0

89..... ....... ..13.5

14.5 

14.0 

16.0 

13.5

14.0 

14.0 

14.0 

17.0 

19.0

90. ........ .....11.0

10.5 

12.5 

12.5 

12.0

11.5 

13.0 

10.5 

11.0 

11.0

91.......... ....12.0

10.0 

10.5 

11.0 

11.5

10.5 

10.0 

12.0 

13.0 

17.0

92..............12.5
B42 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

TABLE 14. Length of largest quartzite roundstones at stations in the western fades (Pinyon Conglomerate), the northern 

fades (Harebell Formation and Pinyon Conglomerate), and the southern fades (Pinyon Conglomerate) Continued

Sta. Length 

No. (in.)

I Sta. Length 

1 No. (in.)

Sta. Length Sta. Length 

No. (in.) No. (in.)

Southern facies Continued

92..............12.5

15.0 

11.5 

14.0

14.5 

13.5 

15.0 

11.5 

13.5

94 13 0

14.0 

16.0 

16.0 

15.0

13.0 

13.0 

14.0 

14.0 

15.0

95.. ........ ....12. 5

14.0 

12.5 

19.0 

20.0

13.5 

13.0 

13.0 

14.0 

21.0

96... ...........13.0

14.0 

12.5 

15.0 

13.0

14.5 

12.5 

14.0 

12.0 

12.5

97.............. 13.5

14.0 

13.5 

15.0

97..............14.5

15.0 

17.0 

16.0 

15.0 

15.0

137............ ..10.0

9.0 

8.5 

8.5 

9.0

10.5 

12.0 

9.5 

10.0 

10.5

138........... ...14.0

10.5 

10.0 

10.0 

10.0

10.0 

13.5 

12.0 

10.0 

12.0

139.............. 10.0

10.5 

11.5 

10.0 

11.0

10.5 

15.5 

13.0 

11.5 

10.0

172. ...... .......13.0

13.0 

13.0 

13.5 

13.0

13.0 

18.0 

17.0

172.... ..........13.0

13.5 

173..............14.5

16.0 

14.5 

14.0 

14.5

15.0 

14.5 

14.5 

14.5 

19.5

180......... .....11.0

10.5 

14.0 

10.5 

12.0

12.0 

11.0 

11.0 

11.0 

13.5

181... ....... ....17.5

12.5 

11.5 

13.0 

13.5

11.5 

13.0 

12.0 

13.5 

12.5

182...... ........ 12.5

12.0 

12.0 

12.5 

13.0

15.0 

13.0 

12.0 

12.5 

13.5

183.... ........ ..13.0

15.5 

13.5 

12.5

14.0 

12.5 

12.5 

15.0 

14.5

185... ...... .....12. 5

13.5 

11.5 

11.5 

11.0

15.0 

11.5 

15.0 

11.0 

11.5

13.0 

15.0 

15.0 

13.0

15.5 

14.0 

14.0 

14.0 

14.5

191. ......... ....12. 5

14.0 

11.5 

11.5 

12.0

14.0 

14.5 

13.0 

13.5 

13.5

193....... ....... 16.0

13.0 

12.5 

14.0 

14.0

Sta. Length 

No. (in.)

Sta. Length Sta. Length 

| No. (in.) No. (in.)

1 Sta. Length 

| No. (in.)

Southern facies Continued

193.---....15.0

12.0 

13.5 

13.0 

14.0

194.. ............ 13.5

11.0 

12.0 

11.5 

16.0

13.0 

13.0 

12.0 

12.0 

12.5

11.5 

16.0 

12.5 

15.0

15.5 

12.0 

13.0 

11.0 

12.0

203... ........ ...14.0

11.5 

12.5 

12.5 

14.5

14.0 

13.0 

13.5 

13.0 

13.0

204... ...........11.0

12.5 

12.0 

12.0 

11.0

10.5 

10.5 

11.0 

11.0

204..............10.5

205... .......... .15.0

13.5 

13.5 

13.5 

13.0

13.0 

13.5 

14.0 

17.0 

15.5

209...... ........14.0

15.0 

15.0 

14.0 

17.0

17.0 

15.0 

15.5 

14.5 

14.5

210. .......... ...16.0

21.0 

14.5 

19.5 

14.0

14.5 

13.5 

14.0 

14.5 

17.5

18.0 

17.0 

17.0 

16.0

16.0 

17.0 

16.0 

20.0 

15.0

212. .............12.5

13.0

212............ ..15.0

12.0 

13.0

13.5 

13.0 

12.5 

14.0 

13.0

213. ............. 14.0

16.5 

15.0 

13.0 

13.0

13.0 

13.5 

17.5 

15.5 

13.5

214.. ............ 17.0

14.0 

14.5 

12.5 

16.0

13.5 

14.0 

18.0 

14.0 

15.0

215..... ...... ...12.0

11.0 

11.0 

15.0 

12.0

18.0 

15.0 

11.0 

12.5 

12.5

13.5 

12.5 

13.0 

12.0

12.0

12.5 

13.0 

12.0

222. .......... ...15.0

15.0 

14.5 

15.0 

14.5

14.5 

16.5 

16.0 

14.0 

15.0

223....... .......12.0

11.5 

14.0 

12.5 

11.5

12.5 

11.5 

12.5 

13.5 

12.0

11A-11......13.0 

11.0 

11.0 

13.0 

11.0

12.0 

11.0 

11.0 

11.0 

11.0

12-14 ....12.0

12.0 

11.0 

12.0 

15.0

11.0 

11.0 

14.0 

11.0 

11.0

TABLE 15. Student's t tests for significant differences in 

mean maximum roundstone length between the northern 

and southern fades and between the Harebell Formation 

and the Pinyon Conglomerate within the northern fades

[x, arithmetic mean ; s-, variance]

TABLE 16. Analysis of variance and estimates of variance 

components for measurements of mean maximum quartzite 

roundstone length (three-level nested design)

[Computed from data in table 14] 

ANALYSIS OF VARIANCE

Number 

of 

stations

Maximum 

roundstone length 

(inches)

~x s^

Student's t 

value

Degrees of 

freedom

Significance

Northern and southern facies

Southern facies..... 49

11.10 2.16 

13.16 2.74

6.42 93 0.01

Harebell Formation and Pinyon Conglomerate within northern facies

Harebell Formation....32 

Pinyon Conglomerate. .14

10.93 2.21 

11.47 2.00

1.13 44 None

Level

Between stations

Between measurements

Degrees 

of

freedom

......942

no

848

ESTIMATES OF V

Level

Facies

Measurement... ...........

Sum 

of 

squares

4,856.5 

1,049.2

2,289.7 

1,517.6 

rARIANCE

Mean 

square

F 

value

1,049.20 42.62 

24.62 13.76 

1.79 

COMPONENTS

Variance component

2.1763 

2.3002 

1.7896

Significance

<0.0001 

<0.0001

Unit size

95 

943

to the distribution of mean maximum roundstone 

length, then data from the northern facies must be 

subdivided into that from the Harebell Formation 

and that from the Pinyon Conglomerate before regional variation is analyzed. Accordingly, the data 

for the northern facies were subdivided and summarized statistically, and the t test was applied to

detect stratigraphic variation (table 15). No significant difference in roundstone length was found, 

and therefore, combination of the data from the 

Harebell and the Pinyon of the northern facies seems 

justified.

Weighted-moving-average maps of mean maximum and maximum quartzite roundstone lengths
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B43

(figs. 30 and 31) were prepared by computer following the procedure described for imbrication vector 

maps. Quartzite roundstone length shows a general 

downstream decrease in both the northern and the 

southern facies (when downstream is defined by 

paleocurrent direction). In addition to downstream 

decrease, roundstone size in both facies also shows 

marked regional differences, including several lobate 

features near the upstream ends. These lobate features are of special interest inasmuch as they represent regions of maximum competency which may be 

interpreted as paleostream courses.

To evaluate the confidence to be placed on any 

interpretation of regional patterns, it is desirable 

to examine the precision of station values upon 

which the regional patterns are based. Therefore an 

analysis of variance (three-level nested model) similar to that made on imbrication data was performed 

(table 16). The analysis shows highly significant 

differences between facies and between stations; 

hence, the method used to sample for mean maximum roundstone length was adequate for distinguishing real differences in length between stations. 

The moving-average maps of roundstone length 

probably depict real variations within facies. Roundstone length at each station is known within ±1.3 

inches (95-percent confidence interval), suggesting 

that contour intervals of about 1 inch are appropriate for the moving-average maps.

The regional variation of mean maximum quartzite length was further investigated by fitting trend 

surfaces of degree 1 through 5 to the data for each 

facies (computer program of Miesch and Connor, 

1968). Total reduction of the sum of squares exceeds 

50 percent for each facies (table 17). Analysis of 

variance of the trend-surface data was used to select 

surfaces which showed a significant fit over the 

preceding surfaces (table 18; Krumbein and Graybill, 1965, p. 333-337). The highest degree trend 

surfaces showing a more significant fit (>90-percent 

confidence level) over the preceding surface for both 

the northern and the southern facies were selected 

for contouring (fig. 32). These surfaces confirm the 

downstream decrease in roundstone size shown by 

the moving-average maps. The lobate features defined by the moving-average map of the northern 

facies are seen to coalesce in the cubic trend of that 

facies; this may be an overgeneralization to the 

trend-surface method, inasmuch as between-station 

differences in roundstone length were shown to be 

highly significant.

SYNTHESIS OF INFORMATION ON SEDIMENT DISPERSAL

Data on paleocurrent directions and regional variation in roundstone size were used to identify the

oo

30

25

20

15

(0 10

2

O

w 5

u.

o

UJ

2 n

1

-

-

-

-g';

'; :

:': .'V : >. :.

i::V: i;J

:. : ; i'.' : :'

': ' : : . "

' :. : , ::

:i ;>;>,

NORTHERN FACIES ~

(Pinyon Conglomerate 

and 

Harebell Formation)

5=11.10

s2 =2.16

-

 : " : "::: :

' ' ''.'.: '' ' 

IW

: :'' ; : :T : 

. T;'. j. ! ;':

i :-: : ' '' ; :

 i'SXi: l

25

20

15

10

I I 

SOUTHERN FACIES

(Pinyon 

Conglomerate)

§2=2.74

10 12 14 16

MEAN MAXIMUM ROUNDSTONE

LENGTH, IN INCHES

18

FIGURE 29. Frequency distributions of 

mean maximum (average of 10 largest) 

quartzite roundstone lengths for stations 

in the northern and southern conglomerate facies, Harebell Formation and 

Pinyon Conglomerate, x, arithmetic 

mean; s2 , variance; N, number of stations.

position and trend of major paleostreams responsible 

for depositing the conglomerates (fig. 33). As interpreted by me, the data outline three distinct stream 

courses and, in the southern facies, possibly two 

other stream courses.
B44 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

/ 

S

V\ NORTHERN 

T, 47 N. \\

--A. \\ FACIES

JACKSON v /HOLE

EXPLANATION

Conglomerate facies 

cp, Pinyon Conglomerate 

ch, Harebell Formation

12

Isopleth for mean maximum 

quartzite roundstone

length, in inches 

Dashed where uncertain

 

Sample station

FIGURE 30. Moving-average isopleth map of mean maximum quartzite roundstone lengths at stations in the

Harebell Formation and the Pinyon Conglomerate.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B45

Conglomerate facies 

cp, Pinyon Conglomerate 

ch, Harebell Formation

Isopleth for maximum quartzite roundstone length, in 

inches

Dashed where uncertain

Sample station

FIGURE 31. Moving-average isopleth map of maximum quartzite roundstone lengths at stations in the Harebell Formation and the Pinyon Conglomerate.
B46 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

Conglomerate facies

cp, Piny on Conglomerate 

ch, Harebell Formation

15

Isopleth for mean maximum quartzite roundstone length, in inches

Sample station

FIGURE 32. Highest degree significant (^90-percent confidence level) surfaces fitted to mean maximum 

quartzite roundstone length at stations in the Harebell Formation and the Pinyon Conglomerate. Each 

surface is cubic, and each is fitted separately to stations in the northern and southern facies.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS

R, 114 W. 30' R. 113 W. R, '12 W, ilO'OO'

B47

PHASE 1: Deposition of the northern _ 

conglomerate facies (Upper Cretaceous and lowest Paleocene)

JACKSON V / HOLE

PHASE 2: Deposition of the southern 

conglomerate facies (Paleocene)

EXPLANATION

Conglomerate facies

Major paleostream

Queried where uncertain

FIGURE 33. Interpreted positions and orientations of major paleostreams responsible for deposition of the

Harebell Formation and the Pinyon Conglomerate.
B48 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

TABLE 17. Percent reduction of the sum of squares for 

trend surfaces fitted to mean maximum quartzite roundstone length in the northern and southern conglomerate 

fades

Northern facies

Added reduction due to:

Quintic surface........ ...... ........ .................... ....... ........

Southern facies

Added reduction due to:

Quintic surf ace......................... .................................

Added 

reduction

...... 2.912

......10.523

......22.317

...... 6.183

......15.228

......38.796

...... 5.279

......11.850

...... .949

...... 1.912

Cumulative 

reduction

2.912

13.435

35.752

41.935

57.163

38.796

44.075

55.925

56.874

58.786

TABLE 18. Analysis of variance of data from trend surfaces 

fitted to mean maximum quartzite roundstone length in the 

northern and southern conglomerate facies

The interpreted relationship between the northern 

and the southern facies must account for the following observations:

1. The southern conglomerate facies is entirely 

Paleocene age; the northern facies is both Late 

Cretaceous and Paleocene age (Love, 1972).

2. The paleostream courses in both facies appear to 

head in the same region, or nearly so.

3. The southern facies contains more volcanic 

roundstones and larger quartzite roundstones 

than does the northern facies.

The interpretation that best accounts for these 

observations is that the conglomerates were deposited 

in two distinct phases. During Late Cretaceous and 

early Paleocene time, east-northeastward-flowing 

streams deposited the northern facies. Somewhat 

later, during Paleocene time, the streams shifted 

southward and deposited the southern facies. Although the two facies shared a similar source, additional volcanics were available to streams depositing 

the southern facies. Cannibalization of the northern 

facies must be considered as a possible source of 

quartzite for the southern facies, but larger quartzite roundstones in the southern facies indicate that 

quartzite was still being brought from elsewhere.

Data on the western conglomerate facies are 

sparse because of its limited distribution. Its age is 

not precisely known, but regional relations suggest 

that it is Paleocene (Love, 1972). Its distinctive 

petrographic attributes suggest that it may represent yet another phase of conglomerate deposition.

OTHER QUARTZITE-BEARING

CONGLOMERATES 

BEAVERHEAD FORMATION

Conglomerates which contain quartzite roundstones similar to those of the Harebell and Pinyon

TABLE 19. Composition (in percent) of roundstones counted in the Divide quartzite conglomerate lithosome (Ryder, 1967) 

of the Beaverhead Formation and in the Lance and Fort Union Formations

[Stations located in figs. 34 and 38; 100 roundstones were identified at each station, x, arithmetic mean ; s, standard deviation ; s2, variance; Tr., trace.

Leaders (......) indicate not present]

Sum Degrees 

Source of of 

squares freedom

Mean 

square

F 

value

Confidence

(percent)

Northern facies

Total...... .................... ........5762.820

Deviations from linear.... ....5595.007

Deviations from quadratic.. 4988. 585 

Due to cubic .. ... .1286.089

Deviations from cubic... ...... .3702.497 

Due to quartic...... ....... ........... 356.315

Deviations from quartic. .....3346.182

Deviations from quintic...... 2468. 619

45

2 

43

3

40

4 

36

5 

31

6

25

83.907 

130.116

202.141 

124.715

321.522 

102.847

71.263 

107.941

146.260 

98.745

0.645 

1.621 

3.126 

.660 

1.481

25+ 

75+ 

95+ 

25+ 

75+

Southern facies

Due to linear....... ...... ...... .......3305.897

Deviations from linear...... ..5215.335

Deviations from quadratic..4765.499 

Due to cubic...... ...................... 1009.766

Deviations from cubic.... ...... 3755.733

Deviations from quartic..... .3674.867 

Due to quintic .... .. 162.926

Deviations from quintic. .....3511.941

47

2 1652.949 

45 115.896

3 149.945 

42 113.464

4 252.442 

38 98.835

5 16.173 

33 111.360

6 27.154 

27 130.072

14.263 

1.322 

2.554 

.145 

.209

99.99+ 

50+ 

90+ 

1+ 

2.25+

Statio

 Quart,,,. Vein

quartz Chert

Sedimentary rocks

Sandstone

Beaverhead Formation

155 .

156...... .......

162 

166. . .......

167 .......

168 

224.............

225.... ...

226...... .......

227.... .........

231... ..........

a;... ......

S2-. .......

........... 66

........... 76

........... 79

........... 83

........... 71

........... 83

........... 85

........... 85

........... 80

........... 74

........... 80

........... 78.36

........... 6.07

........... 36.85

1 

2 

Tr. 

1 

2

1

'.'.'. i

2

0.91 

.83 

.69

11 

10 

13 

13 

12

4 

4 

6 

7 

9 

3

8.36 

3.75 

14.05

Limestone Shale

(Divide conglomerate litho

22 

4 

5 

2 

11

5 

11 

6 

7 

15 

12

9.09 

5.84 

34.09

1 

2

2 

2

0.73 

.90 

.82

Volcanic rocks

Total rocks tuff""

some of Ryder, 1967)

34 

16 

19 .... 1

17 

27

10 

15 

14 Tr. 

17 1 

26 

15

19.09 0.09 0.09 

7.02 

49.29

Porphyritic 

rocks

8 

8 

1

"2

7

i

2

"5

3.09 

3.27 

10.69

Total

8 

8 

2

"2

7

"i

2

"5

3.18 

3.22 

10.36

Lance Formation

66...... ........... 14 7 78 1 79

Fort Union Formation

68...............

109.............

........... 67

........... 63

3 29

5 27

1 

3 1

30 

31

" 1

1Plutonic refers to granitic and gneissic rocks and their relatives, except for stations 225 and 226, where diabase was recorded.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B49

SUMMARY IMBRICATION DIAGRAM 

16 determinations

EXPLANATION

Divide quartzite conglomerate 

lithesome

(Ryder, 1967)of the Beaverhead 

Mean paleocurrent Formation 

direction 61.0°

0 10 20 30 INCHES

I I I

Mean maximum quartzite

roundstone length 

Circle drawn to scale

Station locality and number

Imbrication azimuth

10 MILES 

I

FIGURE 34. Station localities, imbrication azimuths, and mean maximum quartzite roundstone lengths in the Divide 

quartzite conglomerate lithesome (Ryder, 1967) of the Beaverhead Formation.

were first described in the Upper Cretaceous, Paleocene, and Eocene Beaverhead Formation of Idaho 

and Montana by Lowell and Klepper (1953) and by 

Scholten, Keenmon, and Kupsch (1955). Ryder 

(1967) defined an extensive lithesome of quartzite 

cobble conglomerate within the Beaverhead Formation which he termed the Divide quartzite conglomerate lithesome (figs. 1 and 34). Reconnaissance 

studies of the quartzite conglomerate indicated a 

southwesterly or southerly source for the Divide 

(Ryder, 1967; Tanner, 1963). Because the Divide 

quartzite conglomerate lithesome (figs. 35 and 36) 

bears a strong resemblance to conglomerates in the 

Harebell and Pinyon, a petrographic and paleocurrent study was made to determine what, if any, 

relationship exists between them.

The roundstones in the Divide lithesome closely 

resemble those of the Harebell and Pinyon (table 19; 

fig. 37). About 75 percent of the Divide roundstones 

are quartzite, very similar to those in the Pinyon 

north of the Teton Range, but the Divide is less 

quartzite rich than the main body of conglomerates 

in Jackson Hole. Roundstones derived from sedimentary rocks, mainly Madison Limestone and sandstone of undetermined origin, and from quartz 

phenocryst-bearing porphyritic volcanic rocks are 

common; all these lithologies are seen in the Harebell and Pinyon. Hand-specimen and thin-section
B50 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 35. Typical outcrop of the Divide quartzite conglomerate lithosome (Ryder, 1967) of the Beaverhead Formation 

above the West Fork of Indian Creek (sta. 225, fig. 34). Note abundant large quartzite roundstones.

study of quartzite stones from the Divide reveals the 

same range of colors, textures, and mineralogy as 

found in the quartzite stones of the Harebell and 

Pinyon. Clearly the quartzite, other sedimentary 

rock, and quartz phenocryst-bearing volcanic roundstones of the Divide and of the Harebell and Pinyon 

conglomerates were derived from the same or a 

similar source.

Imbrication orientations and maximum quartzite 

roundstone lengths were measured in the Divide 

lithosome (table 20; fig. 34). The imbrication is very 

similar to that observed in the Harebell Formation 

and the Pinyon Conglomerate; 16 determinations of 

50 measurements each showed a strong predominance of northeasterly azimuths, about 30°-60° more 

easterly (depending on location) than in the findings 

of Ryder (1967). Mean maximum length of quartzite 

roundstones at 14 stations showed a northeasterly 

decrease, in agreement with imbrication data. It is 

noteworthy that mean maximum quartzite length 

ranges from 14 to 27 inches in the Divide, generally

well above the sizes noted farther east in the Harebell and Pinyon. The largest quartzite boulder seen 

in the Divide measured 34 inches in long dimension. 

In summary, the Divide quartzite conglomerate 

lithosome shared similar source terranes with the 

Harebell and Pinyon, and paleocurrent evidence indicates that the source of the Divide lay to the southwest. This conclusion is in agreement with that of 

Ryder (1967, 1968) and of Scholten (1968, p. 117) 

that the source of the Divide quartzite conglomerate 

was the Belt quartzite terrane along the eastern 

flank of the Idaho batholith.

FORT UNION FORMATION

Quartzite-bearing conglomerates in the Paleocene 

Fort Union Formation are known in several areas 

along the west flank of the Bighorn Basin (figs. 1 

and 38). Two areas are discussed in the present 

report: (1) the Grass Creek and Left Hand synclines (Hewett, 1926, p. 30-40; Rohrer, 1966b, p. 

16-17) and (2) the Heart Mountain area north of 

Cody (figs. 38, 39, and 40) (Pierce, 1966). That
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B51

*» ? V.JW t- 3r;i£ A^1 ,

«*&SJfcfe?x .-*,

FIGURE 36. Large quartzite roundstones in the Divide quartzite conglomerate lithesome (Ryder, 1967) of the Beaverhead

Formation above Edie Creek (sta. 167, fig. 34).

TABLE 20. Imbrication statistics for 17 determinations of 

50 c-axis orientations each in the Divide quartzite conglomerate lithosome (Ryder, 1967) of the Beaverhead Formation

[Each determination was calculated by averaging 50_oaxis orientations. 

Stations are located in fig. 34. S=vector mean azimuth; <J>=vector mean inclination; /?=vector magnitude; c0.95=radius of spherical circle of confidence; 

A=an indicator of dispersion; x<*>=chi square for angular dispersion about the 

vector mean; d/=degrees of freedom for x2<*>; and x2po=chi square for azimuthal 

dispersion about the vector mean (with 15 degrees of freedom)]

Station

No.

156.............

157.............

162.............

167A..........

B..........

168A..........

B..........

224.............

225A..... . .

B..........

226A..........

B..........

227 A..........

B..........

231A..........

B..........

V

V

'*&<u 

3

......... 98.5

........ 63.8

......... 66.8

........ 27.5

......... 58.0

......... 37.4

......... 31.3

......... 64.3

......... 86.8

78.1

......... 75.2

......... 51.3

......... 92.5

......... 70.2

......... 5.5

......... 22.7

* 

(degrees)

50.7

64.5

55.1

65.4

68.5

56.7

58.7

70.7

59.9

64.8

G4.4

64.8

52.4

55.8

61.2

59.9

R

(absolute value)

35.6

43.6

42.0

39.5

39.7

40.2

39.8

43.3

43.0

42.1

41.1

45.4

42.0

40.0

40.6

45.2

o> 

pi *& 

3

12.9

7.7

8.8

10.4

10.3

10.0

10.2

8.0

8.1

8.7

9.4

6.4

8.8

10.1

9.7

6.5

A

3.4

7.6

6.1

4.6

4.7

5.0

4.8

7.3

7.0

6.2

5.5

10.8

6.2

4.9

5.2

10.3

X2<*>

28.4

22.1

17.9

19.7

19.4

12.6

16.1

18.0

9.1

19.1

6.2

11.5

15.5

22.9

16.7

df

16

10

12

14

13

13

13

10

11

12

12

9

12

13

13

9

X% 

(15#)

21.2

21.9

21.2

19.0

29.8

19.7

30.5

12.6

26.2

15.4

21.9

25.5

12.6

16.1

24.0

23.3

these conglomerates were derived from the same 

source as those of the Harebell Formation and the

Pinyon Conglomerate of Jackson Hole was suggested by Love and Reed (1968, fig. 46). To test 

their hypothesis, I studied quartzite roundstone petrography and paleocurrents in parts of the Fort 

Union, and I studied paleocurrents in the underlying Upper Cretaceous Lance Formation. Heavy minerals from Fort Union and a few Lance sandstones 

were also examined for comparison with those from 

Paleocene and Cretaceous Pinyon and Upper Cretaceous Harebell rocks studied in Jackson Hole.

The Fort Union conglomerates of the Grass Creek 

and Left Hand synclines were not examined by me, 

but their pebble lithology was thoroughly studied by 

Hewett (1926, p. 30-34), who found that quartzite 

roundstones were dominant and that chert, silicified 

wood, quartz, sandstone, and coal were common. He 

reported that th'e chert pebbles, as shown by the 

fossils in them, were probably derived from strata 

of Mississippian to Permian age, and that the quartzite roundstones were probably derived from strata 

of the Belt Supergroup. Hewett suggested a south-
B52 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

westerly source for the conglomerates, and the conglomerates that he pictured (his pis. 12 and 15) 

strongly resemble the Harebell and Pinyon conglomerates of Jackson Hole.

Pebble counts that I made in the conglomerates of 

the Heart Mountain area showed abundant quartzite 

accompanied by sandstone, chert, and white vein 

quartz (table 19; fig. 37). Sandstone and chert are 

more abundant in these conglomerates than in the

Harebell and Pinyon Formations, and the vein 

quartz is unique to the Fort Union Formation. The 

quartzite stones in the Fort Union, as shown by 

detailed examination, do not resemble those in the 

Harebell and Pinyon. Stones extracted from the Fort 

Union matrix are much more angular and irregular 

in shape (fig. 41) than are stones of the Harebell 

and Pinyon, which are characteristically well 

rounded and oblate (fig. 4). The Fort Union quartzCONGLOMERATE 

FACIES

ROUNDSTONE 

LITHOLOGY

QUARTZITE 

COLOR

QUARTZITE 

TEXTURE

QUARTZITE FELDSPAR 

CONTENT 

(PERCENT)

VOLCANIC 

ROCK TYPES

Divide quartzite 

conglomerate 

lithesome (of 

Ryder, 1967) of 

Beaverhead 

Formation

Western facies 

(Pinyon 

Conglomerate)

Northern facies 

(Harebell 

Formation 

and Pinyon 

Conglomerate)

Southern facies 

(Pinyon 

Conglomerate)

53 127

Fort Union 

Formation, 

Heart 

Mountain 

area

Not 

Studied

FIGURE 37. Petrographic affinities of five quartzite-bearing conglomerate facies studied by the author. Roundstone lithology: P, plutonic; V, volcanic; Q, quartzite; S, soft sedimentary rocks; VQ, vein quartz. Quartzite texture: D, detrital; 

S, solution; M, metamorphic. Volcanic rock types: WT, welded tuff. Number in lower left corner indicates number of 

roundstones studied.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B53

Approximate northeast margin of 

quartzite-bearing conglomerate; 

Heart Mountain area

Quartzite-beanng conglomerate;

area of Grass Creek and Left

Hand synclines

SUMMARY CROSSBEDDING DIAGRAM

FORT UNION FORMATION

179 measurements

Mean direction of 

crossbedding 8.6° 

Standard deviation 

85.3°

SUMMARY CROSSBEDDING DIAGRAM 

LANCE FORMATION 

70 measurements Mean directlor of

N crossbedding 76.1° 

Standard deviation

EXPLANATION

Lance Formation

Contact

10 15 INCHES

Mean maximum quartzite roundstone length 

Circle drawn to scale

.110 

Station locality and number

109° Station vector mean of crossbedding

Length of arrow indicates vector strength

FIGURE 38. Station localities, crossbedding orientations, and quartzite roundstone lengths in the Lance and Fort Union 

Formations on the west flank of the Bighorn Basin. Distribution of the Lance and Fort Union Formations from Andrews, Pierce, and Eargle (1947).
B54 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

FIGURE 39. Section of conglomerate in Fort Union Formation north of Cody at bench mark

stone; cgl, conglomerate. View looking north.

'Iron" (sta. 68). SS, sandite stones, as seen in thin section, consist of orthoquartzites with detrital and solution textures (figs. 

37 and 42), sparse feldspathic quartzites, and no 

metamorphic quartzites, in contrast to the Harebell 

and Pinyon quartzite stones, of which 42-51 percent 

were feldspathic and 15-25 percent were metamorphic quartzites.

To examine further the possibility of a common 

source for Upper Cretaceous and Paleocene elastics 

in Jackson Hole and for those in the western flank 

of the Bighorn Basin, heavy minerals were identified in 12 samples of the Lance and Fort Union Formations (table 21) and were compared with heavy 

minerals from their respective time equivalents, the 

Harebell and Pinyon (tables 7 and 10). (Data from 

Upper Cretaceous and Paleocene rocks were combined for each basin in order to test for major 

differences between the provenances of the Upper 

Cretaceous-Paleocene basin fillings. The data are not 

considered sufficient to test for differences between 

formations, because for some formations only a few 

samples were studied and because some of these

TABLE 21. Nonopaque heavy minerals (in percent) in the 

Lance and Fort Union Formations, western flank of the 

Bighorn Basin

[0.0625- to 0.125-mm-size fraction, 100 grains counted per slide. Middle of 

field number corresponds to station number in fig. 38. Tr., trace]

Field No.

3 s

C 

o

1

O< W

 o 

a 

H I w

g 1 10

Lance Formation

L-67-hl......................

126-t/h...................

Average... .......

23 

79

82

61.3

48 

13 

15

25.3

13 

3 

2

6.0

5 

5

1

3.7

10 

0 

0

3.3

0 

0 

0

0

0 

0 

0

0

1 

tr. 

0

.3

0 

0 

0

0

"tr. 

0 

0

0

Fort Union Formation

FU-100-t/h-3 

lOO-t/h-5............

114-t/h................

116-t/h................

119-t/h................

125-t/h................

121-t/h................

122-t/h................

127-t/h................

Average...........

90 

85 

14 

5 

3 

5 

32 

27 

GO

39.0

5 

7 

59 

85 

94 

75 

60 

52 

5

49.1

0 

4 

20 

7 

1 

16 

5 

18 

1

8.0

0 

2

1 

3 

tr. 

0

0 

3

1

1.1

1 

2 

1 

0 

tr. 

tr. 

0 

0 

3

.8

3 

0 

0 

0 

0 

0 

3 

0 

0

.7

0 

0 

2 

0 

2 

2 

0 

0 

0

.7

0 

0 

2 

0 

0 

0 

0 

0 

0

.2

0 

0 

0 

0 

0 

0 

0 

0 

0

0

31 

0 

31 

0 

0

n

0 

0 

0

.3

1Colorless and light-blue-green amphibole. 

2Pleochroic brown amphibole. 

3Kyanite. 

4Pyroxene.

samples vary considerably in relative abundances of 

heavy minerals.) Sphene and brown amphibole, as
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B55

FIGURE 40. Quartzite pebble and cobble conglomerate in the Fort Union Formation north of Cody (sta. 68). Note poor 

sorting and abundant subrounded pebble-sized fraction, both typical of the conglomerate.

shown by microscopic examination of the samples, 

are characteristic of the Jackson Hole suite but not 

of the Bighorn Basin suite. The nonparametric 

Mann-Whitney U test (Siegel, 1956, p. 116-127) 

was applied to detect significant differences in relative abundance of each mineral species (table 22) ; 

zircon, sphene, and possibly brown amphibole showed 

different abundances. The work of Stow (1938, 

1947) farther north compares generally well with 

my data on Lance and Fort Union heavy minerals, 

except that small amounts of staurolite and kyanite 

that he reported were not seen by me.

Crossbedding orientation in the Lance and Fort 

Union Formations along the western flank of the 

Bighorn Basin suggests a westerly or southwesterly 

source (fig. 38). About 10 measurements were taken 

at each of eight stations in the Lance and 21 stations 

in the Fort Union. Orientation of crossbedding 

proved to be easterly in the Lance (vector mean= 

76.1°) and north-northeasterly in the Fort Union 

(vector mean=8.6°). Crossbedding orientation in

TABLE 22. Mann-Whitney U tests for differences between 

means of Upper Cretaceous and Paleocene heavy mineral 

suites from Jackson Hole and those from the Bighorn 

Basin

[Jackson Hole data are computed from tables 7 and 10; Bighorn Basin data, 

from table 21. x, arithmetic mean; s2, variance. Mean and variance are in 

percent. Numbers in parentheses are number of samples]

Jackson Hole (27)

Tourmaline.........

Aim2-.---...-.-.

X

42.6 

19.8 

10.0 

15.0 

1.7 

.9 

.5 

1.2 

8.1

s2

805.1 

497.5 

119.3 

412.0 

4.1 

2.7 

1.0 

3.7 

372.5

Bighorn Basin (12)

X

44.6 

43.2 

7.5 

1.8 

1.4 

.5 

.5 

.3 

0

s2

1370.4 

1082.5 

52.6 

3.5 

8.3 

1.4 

.8 

.4

(U-test)

 0.030 

2.084

.761 

3.073 

.761 

.487 

.091 

1.187 

1.461

Significance

None 

.05 

None 

.01 

None 

None 

None 

None 

.20

1Colorless and light-blue-green amphibole. 

2Pleochroic brown amphibole.

the Fort Union conglomerates of the Heart Mountain 

area, however, is northeasterly.

The quartzite-bearing conglomerates and associated sandstones along the western flank of the Bighorn Basin appear to have been derived from the 

southwest, from the direction of Jackson Hole. Petrographic data suggest that the conglomerates of the
B56 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

Heart Mountain area were not derived from the 

same source as those of the Harebell and Pinyon, 

but perhaps from older Mesozoic and Paleozoic sediFlGURE 41. Typical quartzite roundstones from conglomerate 

in the Fort Union Formation north of Cody (sta. 68). Note 

the subrounded outlines, in contrast to the well-rounded 

outlines of Harebell and Pinyon cobbles (fig. 4).

mentary rocks in the now-buried Washakie Range, 

remnants of which are exposed beneath the edge of 

the Absaroka volcanic field. (See Love, 1939, p. 5, 

90-94.) The quartzites may well have been derived 

from parts of the Flathead Quartzite or from some 

other quartzose sandstone. Petrographic data are not 

sufficient to determine the source of the conglomerates of the Grass Creek and Left Hand synclines, 

but possibly the source was the same as that for the 

conglomerates of the Harebell Formation and the 

Pinyon Conglomerate.

CONCLUSIONS

SOURCE OF CONGLOMERATES

EVIDENCE FOR LONG-DISTANCE TRANSPORT

The coarse conglomerate deposits that I studied 

can be differentiated geographically and petrographically into five distinct deposits: the Divide quartzite 

conglomerate lithosome of Ryder (1967), the western facies (Pinyon Conglomerate), the northern 

facies (Harebell Formation and Pinyon Conglomerate), the southern facies (Pinyon Conglomerate), 

and the conglomerates of the Fort Union Formation 

at Heart Mountain (figs. 1, 37, and 43). Although

A B

FIGURE 42. Photomicrographs of typical textures and mineralogy of quartzite roundstones found in the Fort Union Formation north of Cody (sta. 68). A, Orthoquartzite with well-preserved detrital grain outlines and quartz cement. B, 

Orthoquartzite with indented sutured grain contacts. Crossed nicols.
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B57

petrographically distinct, the first four deposits contain similar roundstones of quartzite, volcanic rock, 

and other sedimentary rock which tie them to the 

same or a similar source terrane (fig. 37). Roundstones of quartzite from each of the four conglomerates show a similar range of color, microscopic 

texture, and mineralogy; roundstones of quartz 

phenocryst-bearing porphyritic volcanic rock are 

present in the same deposits. Paleocurrent studies 

show either easterly, northeasterly, or southeasterly 

sediment transport in all four of these conglomerate 

deposits and in the associated sandstone facies (fig. 

43). Likewise, the length of quartzite roundstones 

and the abundance of soft sedimentary roundstones 

decrease from west to east among the first four deposits. The quartzite roundstones and heavy-mineral 

suites of the Fort Union Formation at Heart Mountain are very different from those of the Harebell 

and Pinyon conglomerates, and therefore the Fort 

Union conglomerates were probably derived from a 

different source.

The distribution of outcrops of potential source 

rocks for the conglomerates can be related to roundstone lithology (fig. 43). Potential source rocks 

include the Precambrian quartzites of the Belt 

Supergroup in Idaho and Montana (Ross, 1947; 

1963, pi. 1), the thick sequence of Precambrian and 

Cambrian quartzites of southeastern Idaho (Crittenden and others, 1971), the Ordovician orthoquartzites of the Kinnikinic and the Swan Peak 

Quartzites (Ketner, 1966; 1968), the Upper Cretaceous Elkhorn Mountains Volcanics and Livingston 

Group, and the widespread Paleozoic and Mesozoic 

sedimentary rocks, including the Flathead and Quadrant Quartzites. The roundstones found in the Harebell Formation and the Pinyon Conglomerate can be 

grouped into two classes: (1) orthoquartzites and 

soft sedimentary rocks available nearby, and (2) 

orthoquartzites, feldspathic quartzites, metamorphic 

quartzites, and volcanic rock available only at great 

distances. From the relationship between paleocurrents and possible source rocks shown in figure 43, 

it is evident that the most likely sources of the latter 

rock types are the Belt quartzites, the Precambrian 

and Cambrian quartzites, the Ordovician orthoquartzites, and the Elkhorn Mountains Volcanics and 

Livingston Group. The suggestion that the quartzite 

roundstones of the Harebell and Pinyon were derived 

at great distance (as much as 100-200 airline miles) 

from Idaho and Montana is not new, having been 

made by Love (1956c, p. 140-141), Eardley (1960, 

p. 87; 1962, p. 326), and Scholten (1968, p. 117).

The locations of Late Cretaceous and Paleocene 

uplifts are also shown in figure 43. These are the

Late Cretaceous and Paleocene Idaho batholith and 

the adjacent southwestern Montana overthrust belt 

(Scholten, 1968), the Late Cretaceous and Paleocene 

Blacktail-Snowcrest, Madison-Gravelly, and Madison-Gallatin arches (Scholten, 1967), the "Laramide" Beartooth uplift (Foose and others, 1961), 

the Late Cretaceous Basin Creek uplift (Love and 

Keefer, 1969), the Late Cretaceous and Paleocene 

ancestral Teton-Gros Ventre uplift (Love, in Behrendt and others, 1968, table 1), the Late Cretaceous 

and Paleocene uplift of the Washakie Range (Love, 

1939, p. 5, 90-94, 106; Keefer, 1965, p. 56), and the 

Late Cretaceous and Paleocene ancestral Wind River 

Range (Keefer, 1957, p. 207-208; Love, 1970, p. 

114). The Blacktail-Snowcrest arch may be early 

Late Cretaceous in age (Ryder and Ames, 1970), 

and the Washakie uplift may extend farther northward to join the Madison-Gallatin arch and the 

Beartooth uplift (H. J. Prostka, oral commun., 

1971). In addition, the now-buried hypothetical Late 

Cretaceous and Paleocene Targhee uplift is shown, 

in figure 43 (Love and Reed, 1968, p. 83-84, 89-90). 

Some of these uplifts may have provided the driving 

mechanism for moving the far-traveled quartzite 

and volcanic roundstones great distances. For example, the transport of the conglomerates may have 

proceeded something like the following (fig. 44) : 

(1) Beginning early in Late Cretaceous time, uplift 

of the Idaho batholith and attendant eastward 

thrusting of the northern Rocky Mountains caused 

stripping off of Belt and Ordovician quartzites, as 

well as other detritus, and ensuing deposition of the 

Beaverhead Formation, including the Divide quartzite conglomerate lithesome (Ryder, 1967; Ryder and 

Ames, 1970; Scholten, 1968). Cretaceous thrusting 

in southeastern Idaho (Armstrong and Oriel, 1965) 

may have initiated erosion and eastward transport 

of Precambrian and Cambrian quartzites and the 

overlying Ordovician orthoquartzites. Quartzite detritus probably traveled eastward and accumulated 

at the present location of the Teton Range; more 

detritus was deposited north and west of the present 

Teton Range (fig. 44A). (2) Subsequent (Late Cretaceous) rise of an ancestral Teton Range (roughly 

corresponding to the ancestral Teton-Gros Veritre 

uplift and the Targhee uplift) shed the quartzite 

detritus farther eastward into Jackson Hole (fig. 

44Z?). (3) During Paleocene time a vast region north 

of the ancestral Teton Range rose, and quartzite 

detritus as well as welded tuff and andesitic volcanic 

rock from the Elkhorn Mountains Volcanics and the 

Livingston Grotip poured into Jackson Hole (fig. 

44C). (4) Also during Late Cretaceous and Paleocene time the Washakie Range rose, causing coarse
B58 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

114°

113

\> J < i J " ^ " 1- v r * ^r V < "r- "

\

^ r "' xl ^ "* >'V ~'tM^ >">r.^ ^ ^ < V/ >A /^l 

< v i ^A v r uooer Cretaceous^ -, r . i- ^S

Uplift of Idaho \ 

atholith to west ^

YELLOWSTONE 

NATIONAL PARK

HYPOTHETICAL

TARGHEE

UPLIFT

Eastern limit of thick Precambrian and

Cambrian quartzite sequence

FIGURE 43. Integration of petrographic and paleocurrent evidence into the geologic setting of the quartzite-bearing

included is the location of the hypothetical
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B59

110° 109° 108"

\ MONTANA

(j

IDAI

, Area c

\^-n

10

f map

WYOMING

""

-" T J r 1 \

r

MONTANA

WYOMING

Vein quartz^'""

Heart Mountain

EXPLANATION

Late Cretaceous Paleocene 

and Paleocene

Mean directions of paleocurrents

25 INCHES

Mean maximum quartzite roundstone length, upstream

and downstream 

Circle drawn to scale

Plutonic rocks. Volcanic rocks

Soft sedimentary rocks Quartzite

Average clast lithology 

D, Divide quartzite conglomerate lithosome of Ryder (1967) of

Beaverhead Formation

W, western conglomerate fades; Pinyon Conglomerate 

N, northern conglomerate fades; Pinyon Conglomerate and Harebell Formation

S, southern conglomerate fades; Pinyon Conglomerate 

H, conglomerates of Fort Union Formation at Heart Mountain

Uplift of Late Cretaceous and Paleocene age unless otherwise 

noted

50 MILES 

_I

conglomerates. Distribution of possible source rocks and Late Cretaceous and Paleocene uplifts is shown. Also 

Targhee uplift of Love and Reed (1968).
B60 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

110° 109° I 

108°

_ Southeastern limit 

of quartzites of 

Belt Supergroup

I

O-IT43'

Eastern limit of thick 

Precambrian and

Cambrian 

quartzite sequence

 ________I____

WYOMING

114°

A. EARLY LATE CRETACEOUS

112° 111° 110° 109° 108°

v-Y>

Southeastern limit 

of quartzites of 

Belt Supergroup

Elkhorn * t \ 

Mountains ,J '

\«- ^"Volcanics ^ ' i

\^ ^»^iV.x '

/'.^ r^t

1^ r- Livingston Group v \ 

U(volcaniclastic rocks)i

I r^N

^OTT

44

43'

Eastern limit of thick 

Precambrian and

Cambrian 

quartzite sequence

-________I____

B. LATE CRETACEOUS AND EARLY PALEOCENE

FIGURE 44. Suggested interpretation according to the long-distance-transport

bearing conglomerates
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS

110° 109°108°

B61

113" 112

I - Livingstone Group . 

v^volcaniclastic rocks)'

r' JrJ -»* '

of quartzites of 

Belt Supergroup

5 *'*« V/vX/N&J

C 

/ uPciVrC 

^ - %>r..: ': ..-?4,t 

rr? ""\ 

>? %>%Wb, '<, \ i \ w^^^=^--\-^--

Eastern limit of thick 

Precambrian and

Cambrian 

quartzite sequence

46

45

112°

C. PALEOCENE

111°

ri. A .

A% Elkhorn >A r-\

\ ^ Mountains ,A U J

V ^ Volcanics^ i

w vV

^ ^ > * \«v > ,. X 

7 ^^^^ ^ v^ A i t y 

p Livingston^ Group

109° 1 

108°

Southeastern limit , > u"J l'-i 'VA V Kvolcaniclastic rocks),.

of quartzites of M^ >- » v -. VA/ v"" ' ' %A ^- - A^'" % -» n

Belt Supergroup t___ _L" V^^ " r""- r -> L < > N "" V/

MONTANA_ 

WYOMING

CYELLOWSTONE^. 

C NATIONAL /"

PARK 'I

<\ ( Northern

" ' (Pmyon

Conglomerate ForfUnion F

D,v,de quartzit 

conglomerate 

lithosome of 

Ryder (1967)

of Beaverhead

ANCESTRAL T 

TETON RANGE; 

.ol --

(Pmyon Conglomerate* Eastern limit of thick

Precambrian and

Cambrian

quartzite sequence

50 100 MILES

D. LATE PALEOCENE

hypothesis of the sources, dispersal routes, and depositional areas of the quartzite- 

(circle pattern).
B62 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

Paleozoic orthoquartzite and chert detritus to be 

deposited along the western flank of the Bighorn 

Basin (fig. 44C). Thus, quartzite roundstones and 

other detritus were transported eastward from the 

eastern flanks of the Idaho batholith to Jackson Hole 

by successive uplift and reworking of conglomerate 

deposits (fig. 44D).

OBJECTIONS TO LONG-DISTANCE TRANSPORT

Objections to the hypothesis of long-distance 

transport of the conglomerates may be briefly summarized under three categories: mechanics, lack of 

evidence for reworking, and gold distribution.

The problem of mechanics arises from the immense volume of roundstones (perhaps 560 cu mi, 

of which 75 cu mi remains, according to Love, 1972) 

which must be moved a total distance of at least 100 

miles (from the nearest extensive quartzite terrane) 

to perhaps 280 miles (from the eastern edge of the 

Idaho batholith). It must be emphasized that the 

task of roundstone transport was aided considerably 

by humid conditions (and hence abundant runoff), 

by steep gradients that probably existed, and by a 

time span of probably millions of years. All these 

requirements are consistent with fossil evidence and 

the physical characteristics of the conglomerates. A 

few calculations are presented below to illustrate 

the range of physical conditions required to transport the roundstones found in the conglomerates. It 

can be shown that the long-distance-transport hypothesis is consistent with estimates of stream velocities, depths, and slopes and that these parameters 

yield reasonable estimates of the total relief required to move the roundstones.

The velocities and depths necessary to transport 

the roundstones are not so great as might be generally supposed. They can be calculated according to 

the sixth-power law and the Manning equation:

Vb=9d%, (sixth-power law)

where Vb is the bottom velocity, in feet per second, 

and d is roundstone diameter, in feet; and

R% s% 

F=1.49 , (Manning equation)

it

where R is the hydraulic radius, in feet (depth in 

very wide streams), s is the slope, and n is a roughness factor. Details of the sixth-power law were 

discussed by Malde (1968, p. 46-47), and details of 

the Manning equation, by Leopold, Wolman, and 

Miller (1964, p. 156-158). The velocity can be 

calculated directly from roundstone diameter (approximated by length) by the sixth-power law. Alternatively, one may also use the Nevin-Hjulstrom 

formula (Fahnestock, 1963, p. 29-30) to compute 

Ft, the traction velocity, but the results obtained are 

only slightly different for the particle sizes under

consideration. The depth (R, the hydraulic radius) 

can next be calculated from the Manning equation 

by using the velocity obtained from the sixth-power 

law, by assuming slope values ranging from 0.01 to 

0.10, known to be common on larger alluvial fans 

(Denny, 1965, table 7; Riccio, 1962, p. 28), and by 

assuming a roughness factor of 0.04-0.06 for alluvial 

channels with coarse detritus (Barnes, 1967; Leopold and others, 1964, p. 158). The results are shown 

in figure 45. According to these calculations, a typical maximum roundstone size of 1 foot suggests a 

bottom velocity of 9 feet per second and a possible 

depth of less than 7 feet; the 4.2-foot boulder at the 

north end of the Teton Range (fig. 6A) could be 

moved by currents traveling 18 feet per second in 

water 2-20 feet deep. The work of Fahnestock 

(1963) on the White River, Mount Rainier, Wash., 

provides additional insight into the conditions necessary for the transport of coarse detritus. He observed that in the White River the velocities were as 

much as about 10 feet per second in water about 2 

feet deep (Fahnestock, 1963, fig. 8), and the largest 

particles seen in transit were 1.8 feet in diameter 

(p. 29). Hence, the computed velocities and depths 

based on roundstone size in the Harebell and Pinyon 

are probably generous.

The range of slopes used in the above calculations 

leads to realistic estimates of the total relief involved in the transport of the conglomerates. The 

range of slopes is taken from modern alluvial fans, 

which, as will be shown later, constitute the closest 

modern analogs to the conglomerates of the Harebell 

Formation and the Pinyon Conglomerate. A slope 

of 1 percent (52.8 ft per mi) would project to a total 

relief of 5,280 feet in 100 miles and 14,800 feet in 

280 miles, the range of total distances that the 

roundstones may have moved. Under these conditions, streams flowing 9 feet per second and having 

depths of 4-7 feet are capable of transporting roundstones 1 foot in diameter (fig. 45). A further projection of total relief in 100 miles and in 280 miles 

follows: A 2-percent slope (105.6 ft/mi), 10,560 and 

29,600 feet, respectively; 5-percent slope (264 

ft/mi), 26,400 and 74,000 feet; and a 10-percent 

slope (528 ft/mi), 52,800 and 148,000 feet. Assuming that the quartzite roundstones moved the maximum distance of 280 miles, that the total relief 

involved slopes averaging 10 percent, and that the 

relief was distributed among three stages of uplift 

and roundstone transport as shown in figure 44, then 

the relief involved in each erosion epoch would have 

averaged nearly 50,000 feet. At 5-percent slope, the 

relief per erosion epoch would be reduced to about 

25,000 feet, and so on. Thus only the slope values 

above 5 percent yield unreasonable estimates of
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B63

relief. As shown earlier, slopes of 5 percent or less 

also yield reasonable estimates of velocity and depth. 

The lack of evidence for reworking of the conglomerates is a result of the general paucity of fine15

10

t 3

B

c

o.i 0.5 1.0 

ROUNDSTONE DIAMETER, IN FEET

10

FIGURE 45. Velocities and depths of streams necessary to 

transport roundstones found in the Harebell Formation 

and the Pinyon Conglomerate. A, Velocity required to 

move roundstones of various diameters according to the 

sixth-power law and the Nevin-Hjulstrom formula. B, 

Depth of water predicted from roundstone diameter using 

the sixth-power law to derive velocity and the Manning 

equation to compute depth (approximated by R, the hydraulic radius), assuming a roughness of n=0.06 and a 

range in slope of 1-10 percent. C, Same as B except a 

roughness of n=0.04 is assumed.

grained facies in the conglomerates. Long-distance 

transport through reworking of successive conglomerates would be expected to produce an abundant 

supply of fine-grained detritus. In considering this 

problem one must not overlook the sandstone matrix, 

seen everywhere in the conglomerates. The roundstones are closely packed and probably have a porosity of about 25 percent, comparable to that produced 

by "closest," or rhombohedral, packing of spheres 

(PettiJohn, 1957, p. 83-85). If the original volume 

of the conglomerates approached 560 cubic miles 

(Love, 1972), then approximately 25 percent, or 140 

cubic miles, of sand was contained between the 

roundstones. Based on the 75 cubic miles of conglomerates remaining, as estimated by Love (1972), 

19 cubic miles of sand is still present. In addition to 

the great volume of sand produced, the high degree 

of rounding of the quartzite stones themselves attests 

to prolonged transport and perhaps reworking.

The gold distribution in the conglomerates presents a third problem regarding long-distance transport. The Divide quartzite conglomerate lithosome 

of Ryder (1967) and the western facies of the Pinyon Conglomerate contain only very small quantities 

of fine-grained gold, whereas the sandstone facies, 

northern conglomerate facies, and southern conglomerate facies all contain considerably more gold (J. C. 

Antweiler, unpub. data). If the conglomerates were 

all derived from the same source and were cycled 

through comparable depositional episodes, then they 

might be expected to contain comparable amounts 

of gold. Here it is important to distinguish between 

the sources of various components of the conglomerates, such as quartzite or volcanic roundstones. As 

mentioned earlier, the quartzite roundstones probably had a source terrane different from that of 

some of the volcanic roundstones, and the sedimentary 

roundstones may have had yet a third source. The 

first two (quartzite and volcanics) are probably far 

traveled, whereas the sedimentary rocks may have 

come from a wide area nearby, to the northwest of 

Jackson Hole. The source of the gold may have been 

any one or more of the several sources suggested 

for the coarser detritus. Also not evaluated is the 

possibility of concentrating the gold by successive 

cycles of reworking, so that the conglomerates (and 

sandstones) farthest downstream, or youngest in 

age, may contain the most gold.

ALTERNATIVE EXPLANATIONS

Although I favor long-distance transport of the 

conglomerates to explain their source, at least three 

alternative hypotheses were considered and rejected. 

These, in decreasing order of likelihood, are: (1) 

Derivation from the Targhee uplift, a now-buried
B64 GEOLOGY OF GOLD-BEARING CONGLOMERATES IN NORTHWESTERN WYOMING

hypothetical source beneath the Snake River Plain 

northwest of the Teton Range; (2) derivation from 

far-thrusted quartzites to the west; and (3) derivation from local quartzite terranes.

Derivation from the hypothetical Targhee uplift 

was proposed by Love (Antweiler and Love, 1967, 

p. 2; Love, 1968, 1972; Love and Reed, 1968, p. 

83-84). The Targhee uplift hypothesis is in harmony with known transport directions in the Harebell and Pinyon and accounts for the large boulders 

found in the Pinyon Conglomerate north of the Teton 

Range. Love (1972) suggested that the absence of 

Upper Cretaceous strata and the presence of easterly 

dips in pre-Pinyon rocks north of the Teton Range 

are further evidence of an uplift nearby. The main 

objections to the Targhee uplift hypothesis are 

three: (1) It appeals to an undetected, now-buried 

source; geophysical studies did not reveal any evidence for a buried uplift (Pakiser and Baldwin, 

1961; LaFehr and Pakiser, 1962; Mabey, 1966). (2) 

The present distribution of terranes containing thick 

quartzite sequences suggests that much of the proposed Targhee uplift region did not contain abundant quartzite during Cretaceous time (figs. 1 and 

43). (3) The location and southwestern or western 

source of the Divide quartzite conglomerate lithosome of Ryder (1967) is not easily reconciled with 

the proposed location of the Targhee uplift, to the 

south and southeast of the Divide.

The hypothesis of quartzite derivation from fartraveled thrust plates near Jackson Hole is not 

supported by the present distribution of quartzites 

in the overthrust belt of southwestern Montana, 

Idaho, and southwestern Wyoming (fig. 43). Paleocene, Cretaceous, and earlier thrusting (Armstrong 

and Oriel, 1965; Scholten, 1968) of Belt, Precambrian and Cambrian, and Ordovician quartzites 

probably played some role in elevation and eastward 

transport of the quartzite later deposited in Jackson 

Hole. However, the present eastward limit of 

thrusted Belt quartzites is in extreme southwestern 

Montana and adjacent Idaho (Ross, 1963, pi. 1), 

and the present eastward limit of the thrusted Precambrian and Cambrian quartzite sequence of Utah 

and southeastern Idaho is along a line running 

roughly from Blackfoot, Idaho, past Bear Lake 

(Crittenden and others, 1971; S. S. Oriel, oral commun., 1971). Likewise, the Ordovician Kinnikinic 

and Swan Peak quartzites are found in approximately the same region as the Precambrian quartzites (Ketner, 1968, figs. 1 and 3). Hence, the 

potential quartzite sources preserved today in the 

overthrust belt are still more than 100 miles from 

the nearest conglomerates in Jackson Hole.

Derivation of quartzite from local quartzite terranes (Bengston, 1956, table 1) is probably the 

weakest hypothesis. Local quartzite terranes are far 

too small to supply the required quantity of quartzite, and derivation of detritus from local uplifts is 

not supported by paleocurrent evidence.

DEPOSITIONAL ENVIRONMENT

The conclusion that the Harebell Formation and 

the Pinyon Conglomerate were deposited in a predominantly continental environment is supported by 

several lines of evidence:

1. Continental fossils, including vertebrates, freshwater mollusks, leaves, wood, and pollen, are 

common (Love, 1956b).

2. Sedimentary features, including abundant percussion marks on quartzite roundstones and 

imbrication inclinations of 28°-29°, correspond 

very well with modern fluvial environments.

3. The great quantity of well-sorted conglomerate 

does not have many known analogs in the 

marine geologic record. At present, the southern facies is a maximum of about 32 miles long 

(down paleoslope), 17 miles wide (along 

paleostrike), and from 1,000 to 1,500 feet thick 

upstream to slightly more than 200 feet thick 

at the downstream end. Only slides and turbidity currents are thought to be capable of carrying large quantities of coarse detritus very far 

in marine waters, and these are ruled out by 

the sorting and shingling of clasts in the conglomerates.

4. The Harebell and Pinyon possess strongly unidirectional paleocurrent systems, in contrast to 

the greatly dispersed paleocurrents in the underlying mixed marine and continental sandstones.

Evidence for deposition in a marine environment 

is found in the occurrence of possible marine microfossils (dinoflagellates and acritarchs) and MytUus*! 

clams (Love, 1972) in parts of the Harebell Formation. This evidence suggests that deposition of the 

Harebell Formation was occasionally at or below 

sea level.

A subsiding-alluvial-fan model best fits the geometry of the conglomerate deposits. Alluvial fans 

in the semiarid Southwest range in radius from a 

few hundred feet to about 7 miles (Blissenbach, 

1954; Denny, 1965) and may be as much as 1,000 

feet thick (Eckis, 1928). Exceptional alluvial fans 

are reported with a radius of as much as 40 miles 

(Grabau, 1913, p. 584). The lobate features outlined 

by analysis of roundstone length might be explained 

by the semicircular shape of most alluvial fans noted 

by Bull (1968). The great thickness of coarse clas-
PETROLOGY AND PALEOCURRENTS, HAREBELL AND PINYON FORMATIONS B65

tics is also explained by the alluvial-fan model. Very 

coarse detritus, as much as 6 feet in diameter and 

not uncommonly 3 feet, is reported from some fans 

in California (Goldman, 1968). Downstream decrease in particle size in alluvial fans is widely noted 

(Blissenbach, 1954; Eckis, 1928; Goldman, 1968). 

Although poorly sorted sediments are common in 

alluvial fans, Blissenbach (1954) stressed the variability found in sorting and rounding of fan deposits 

and pointed out the strong effects of source rock and 

reworking on these characteristics. As noted earlier, 

transport of quartzite roundstones in the Harebell 

and Pinyon over long distances probably involved 

considerable reworking. The sedimentary structures 

observed correspond closely with those seen in fans, 

except that poorly sorted deposits of possible mudflow origin are not seen in the conglomerates. Blissenbach (1954) noted that mudflow deposits form 

as much as 40 percent of some alluvial fans in Arizona, but he suggested also that mudflows become 

less numerous with increased precipitation. Plant 

remains in the conglomerates suggest a much more 

humid climate during Harebell and Pinyon time 

(Love, 1956c) than at present in the Southwest.

The characteristic geographic setting of an alluvial fan is at the base of an imposing mountain 

front, generally at a fault or fault-line scarp (Blissenbach, 1954). If the alluvial-fan model is correct, 

then rapidly rising mountain ranges must have been 

present upstream from each conglomerate deposit 

at the time of deposition of the fan. Such a mountain 

range has been postulated for the source of the 

Divide quartzite conglomerate lithosome (Scholten, 

1968). Similarly, a mountain range in the present 

region of the Teton Range but extending farther 

north would be needed to supply conglomerate to 

Jackson Hole. Rapidly rising source areas to the west 

and northwest of Jackson Hole are prerequisite to 

transport of the coarse detritus of the Harebell Formation and the Pinyon Conglomerate. Subsidence of 

the alluvial fans (to below sea level during Harebell 

time) must have been considerable and prolonged to 

allow accumulation of the great thickness of conglomerate seen in the Harebell and Pinyon.

The sedimentary features observed within the 

conglomerates are also consistent with an environment of deposition on alluvial plains. Coarse alluvial 

deposits with imbrication, crossbedding, and downstream decrease in particle size are well documented 

(Plumley, 1948; Potter, 1955; Schlee, 1957b). However, the geometry and great thickness of the 

conglomerates do not favor an alluvial-plain interpretation.

The discussion of depositional models indicates 

that high mountain ranges west of Jackson Hole

(corresponding roughly to the Teton-Gros Ventre 

arch and the hypothetical Targhee uplift) probably 

were the immediate source of the coarse detritus 

seen in the Harebell Formation and the Pinyon Conglomerate. Paleocurrent directions in the conglomerate facies indicate that an ancestral Teton Range 

must have occupied nearly the same location as the 

present Teton Range during Late Cretaceous time 

but that ranges of high relief extended much farther 

north during Paleocene time. The ancestral Teton 

Range was not eroded to the Precambrian, as is the 

present Teton Range, but probably consisted of a 

thick mantle of quartzite roundstone conglomerates 

overlying the Paleozoic rocks now present. The 

mantle of quartzite detritus probably was derived 

from highlands still farther west where abundant 

Precambrian and lower Paleozoic quartzites are 

presently known. The present outliers of Pinyon 

Conglomerate north of the Teton Range (western 

facies) may indeed be the remnants of this vast 

mantle of quartzite detritus. These outliers overlie 

the Madison Limestone, in harmony with the pictured model of the ancestral Tetons. The lithology of 

the outliers more closely resembles that of the Divide 

quartzite conglomerate lithosome farther west than 

that of the Harebell Formation and the Pinyon Conglomerate to the east (fig. 37). Uplift of the ancestral Teton Range could have been accomplished by 

activation of the Teton fault (fig. 44£). The Teton 

fault is a major structural feature, and although no 

geologic evidence has yet been advanced for activity 

before the Pliocene (Love, 1956c), the intense tectonism evidenced by the conglomerates themselves 

might suggest a far greater antiquity for the fault. 

In summary, the conglomerate facies of the Harebell Formation and the Pinyon Conglomerate were 

deposited as fans of coarse alluvial detritus along 

the eastern margin of the ancestral Teton Range. 

The ancestral Tetons rose rapidly and were quickly 

stripped of their mantle of quartzite detritus. Coarse 

quartzitic detritus (the northern facies) was shed 

directly east from the region of the present Teton 

Range during Late Cretaceous and early Paleocene 

time; an extensive region north of the ancestral 

Teton Range rose rapidly during Paleocene time, 

shedding coarse quartzitic and volcanic detritus (the 

southern facies) southeastward into Jackson Hole.

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US. GOVERNMENT PRINTING OFFICE: 1972 O 479-609