New Interpretations of Paleozoic 

Stratigraphy and History in the 

Northern Lararnie Range and 

Vicinity, Southeast Wyoming

IT, § PAPER

New Interpretations of Paleozoic 

Stratigraphy and History in the 

Northern Laramie Range and 

Vicinity, Southeast Wyoming

By WILLIAM J. SANDO and CHARLES A. SANDBERG

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1450

A revision of Paleozoic

I* j stratigraphy based on

0 . ^ , . , .

biostratigraphic analysis

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1987
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Sando, William Jasper.

New interpretations of Paleozoic stratigraphy and history in the northern Laramie range and vicinity, southeast Wyoming.

(U.S. Geological Survey professional paper ; 1450)

"A revision of Paleozoic stratigraphy based on biostratigraphic analysis."

Bibliography: p.

Supt. of Docs, no.: I 19.16:1450

1. Geology, Stratigraphic Paleozoic. 2. Paleontology Paleozoic. 3. Geology Laramie Mountains (Wyo. and Colo.)

4. Paleontology Laramie Mountains (Wyo. and Colo.) I. Sandberg, Charles A. (Charles Albert), 1929-

II. Title. III. Series. 

QE725.S19 1987 551.7'2'097879 86-600194

For sale by the Books and Open-File Reports Section, U.S. Geological Survey, 

Federal Center, Box 25425, Denver, CO 80225
CONTENTS

Page

Abstract ------------------------------------------------- i

Introduction --------------------------------------------- i

Subjacent rocks ------------------------------------------ 2

Fremont Canyon Sandstone ------------------------------- 3

Description ------------------------------------------ 3

Age and correlation ---------------------------------- 4

Previous studies ---------------------------------- 4

Present analysis --------------------------------- 4

Origin ----------------------------------------------- 7

Englewood Formation ------------------------------------ 7

Description ------------------------------------------ 7

Fossils, age, and correlation --------------------------- 9

Origin ----------------------------------------------- 10

Madison Limestone --------------------------------------- 10

Description and discussion ---------------------------- 10

Status of Guernsey Formation ------------------------- 12

Big Goose Member ----------------------------------- 12

Description -------------------------------------- 12

Fossils, age, and correlation ----------------------- 12

Origin ------------------------------------------- 13

Little Tongue Member -------------------------------- 13

Description -------------------------------------- 13

Fossils, age, and correlation ----------------------- 14

Origin ------------------------------------------- 14

Bull Ridge Member ----------------------------------- 14

Madison Limestone Continued 

Bull Ridge Member Continued

Description ---------------------

Fossils, age, and correlation ------

Origin --------------------------

Post-Madison, pre-Casper solution features 

Casper and Hartville Formations ---------

Darwin Sandstone Member ----------

Description ---------------------

Fossils, age, and correlation ------

Origin --------------------------

Post-Darwin beds -------------------

Description ---------------------

Fossils, age, and correlation ------

Origin --------------------------

Stratigraphic section descriptions ---------

Fremont Canyon --------------------

Casper Mountain Road A ------------

Casper Mountain Road B ------------

Casper Mountain TV Tower ----------

Banner Mountain -------------------

Steeple Pasture ---------------------

Box Elder Canyon -------------------

Hartville Canyon --------------------

References cited -------------------------

ILLUSTRATIONS

14

15

15

15

15

16

16

17

17

17

17

17

17

18

18

21

23

27

29

31

33

36

37

[Plates are in pocket]

PLATE 1. Correlation of stratigraphic sections in study area with Blue Creek section in southern Bighorn Mountains. 

2. Stratigraphy of Englewood Formation and adjacent rocks in study area.

Page

FIGURES 1, 2. Maps of:

1. Wyoming showing present structural features and the area studied ---------------------------------------- 2

2. Southeast Wyoming showing location of stratigraphic sections discussed in this report ---------------------- 3

3, 4. Maps showing:

3. Traditional restored distribution of quartz sandstones of Late Cambrian and Early Ordovician, Middle

and Late Ordovician, and Late Devonian ages in the northern Cordilleran region ----------------------- 5

4. Revised, partly restored distribution of quartz sandstones of Late Cambrian and Early Ordovician, Middle 

and Late Ordovician, and Late Devonian ages in the northern Cordilleran region based on revised 

interpretation of sandstones in southeast Wyoming --------------------------------------------------- 8

5. Chart showing correlation of Upper Devonian and Mississippian sequences at selected localities in southern

Wyoming -------------------------------------------------------------------------------------------------- 11

6. Interpretive field sketch of geologic relationships at contact between Madison Limestone and Casper Formation at

Fremont Canyon section ------------------------------------------------------------------------------------ 16

7. Geologic sketch map of Fremont Canyon section ------------------------------------------------------------------ 18

8. Photograph showing Precambrian granite, Fremont Canyon Sandstone, Englewood Formation, and Big Goose and

Little Tongue Members of Madison Limestone in Fremont Canyon section ------------------------------------- 19

m
IV CONTENTS

Page

FIGURE 9. Geologic sketch map of Casper Mountain Road and TV Tower sections --------------------------------------------- 22

10 12. Photographs showing:

10. Fremont Canyon Sandstone; Englewood Formation; Big Goose, Little Tongue, and Bull Ridge Members of 

Madison Limestone; and Casper Formation exposed in cliffs at front of Casper Mountain northeast of 

Casper Mountain Road section ---------------------------------------------------------------------- 23

11. Fremont Canyon Sandstone; Englewood Formation; Big Goose, Little Tongue, and Bull Ridge Members of 

Madison Limestone; and Casper Formation exposed in west wall of canyon east of Casper Mountain 

TV Tower section ---------------------------------------------------------------------------------- 28

12. Solution breccia in lower solution zone of Little Tongue Member of Madison Limestone, unit 10 of Casper

Mountain TV Tower section ------------------------------------------------------------------------- 29

13. Geologic sketch map of Steeple Pasture and Banner Mountain sections -------------------------------------------- 30

14-16. Photographs showing:

14. Precambrian granite; Fremont Canyon Sandstone and Englewood Formation; Big Goose and Little Tongue 

Members of Madison Limestone; and Casper Formation exposed in east wall of Lower Deer Creek 

Canyon near Banner Mountain and Steeple Pasture sections ------------------------------------------ 31

15. Fremont Canyon Sandstone resting on Precambrian granite at Box Elder Canyon section ------------------- 33

16. Precambrian granite, Fremont Canyon Sandstone, Englewood Formation, and Big Goose Member of

Madison Limestone at Box Elder Canyon section ----------------------------------------------------- 34

17. Geologic sketch map of Box Elder Canyon section ---------------------------------------------------------------- 34

18. Photograph showing Precambrian granite; Fremont Canyon Sandstone; Englewood Formation; Big Goose and Little 

Tongue Members of Madison Limestone; and Casper Formation exposed in east wall of Box Elder Canyon near 

section traverse -------------------------------------------------------------------------------------------- 35

TABLES

Page

TABLE 1. Characteristics of Cambrian to Devonian quartz sandstones in the northern Cordilleran region -------------------------- 6

2. Diagnostic Devonian and Mississippian conodonts from the Englewood Formation -------------------------------------- 9

3. Diagnostic Kinderhookian conodonts from the Big Goose Member of the Madison Limestone ----------------------------- 13
NEW INTERPRETATIONS OF PALEOZOIC STRATIGRAPHY AND 

HISTORY IN THE NORTHERN LARAMIE RANGE AND VICINITY,

SOUTHEAST WYOMING

By WILLIAM J. SANDO and CHARLES A. SANDBERG

ABSTRACT

The Paleozoic sequence in the northern Laramie Range and vicinity begins with a basal quartzarenite that rests unconformably on 

Precambrian granite or metamorphic rocks and passes upward into 

predominantly carbonate rocks of Devonian to Permian age. 

Quartzarenite formerly regarded as Deadwood Formation (Upper 

Cambrian and Lower Ordovician) and as basal Guernsey Formation 

at the base of the sequence is referred to the Fremont Canyon Formation (new) and is correlated with the Parting Formation (Upper Devonian) of central Colorado. The Fremont Canyon Sandstone is succeeded by terrigenous and dolomitic rocks belonging to the 

Englewood Formation, whose Late Devonian and Early Mississippian age is determined by conodonts. The boundary between the 

Devonian and Mississippian Systems is a disconformity within the 

Englewood Formation. The Englewood is conformably overlain by 

carbonate rocks assigned to the Madison Limestone, which ranges in 

age from Early Mississippian (Kinderhookian) to Late Mississippian 

(early Meramecian), based on conodont, foraminifer, and coral data. 

The Madison Limestone includes, in ascending order, the Big Goose, 

Little Tongue, and Bull Ridge Members, which were described previously from outcrops in north-central Wyoming. The term "Madison 

Limestone" is extended into the Hartville uplift area, replacing 

"Guernsey Formation," which is an outmoded name. The Madison 

Limestone is overlain disconformably by the Casper Formation or by 

the Hartville Formation of Pennsylvanian and Permian age. Only 

the lower 100 feet (30.5 meters) of the Casper or Hartville was examined in this study. The basal unit of the Casper and Hartville consists 

of quartzarenite assigned to the Darwin Sandstone Member, which is 

a member of the Amsden Formation in areas west and north of the 

study area. The Paleozoic sequence from the base of the Fremont 

Canyon Sandstone into the lower part of the Casper Formation has 

a maximum thickness of about 625 feet (191 meters).

The area studied was characterized by deposition of quartzarenite 

(Fremont Canyon Sandstone) derived from the Transcontinental 

Arch in marginal-marine and peritidal environments during Late 

Devonian time. These environments gave way to terrigenous and 

carbonate deposition on intertidal flats and beaches (Englewood Formation) during latest Devonian and earliest Mississippian (early 

Kinderhookian) time. The Devonian-Mississippian boundary, however, was marked by an interruption in sedimentation. Later Kinderhookian to middle Osagean time was characterized by carbonate 

deposition in intertidal mud flats and lagoons (Big Goose Member of 

Madison Limestone). Evaporites were deposited in restricted lagoons 

(lower solution zone of Little Tongue Member of Madison Limestone)

at the end of middle Osagean time or the beginning of the late 

Osagean, followed by normal-marine offshore carbonate deposition 

(upper part of Little Tongue Member of Madison Limestone) in the 

late Osagean. Another episode of restricted lagoonal deposition (upper solution zone of Bull Ridge Member of Madison Limestone) occurred at the end of the Osagean or the beginning of the Meramecian. 

This was followed in the early Meramecian by a brief return to 

normal-marine carbonate deposition (upper part of Bull Ridge Member of Madison Limestone), which was succeeded by further shallowing that culminated in uplift, emergence, and karst development 

during Late Mississippian (Meramecian and Chesterian) time. The 

sea returned to the area in Pennsylvanian time and reworked sand 

deposits derived from the Transcontinental Arch (Darwin Sandstone 

Member of Casper and Hartville Formations), forming beaches and 

offshore bars. During later Pennsylvanian time (Desmoinesian and 

later), the area was characterized by alternations of normal-marine 

offshore carbonate deposition and intertidal or supratidal carbonateflat deposition, interrupted by pulses of quartz sand deposition in 

beaches and offshore bars.

INTRODUCTION

Exposures of Paleozoic rocks in the Laramie Range 

and Hartville uplift of southeast Wyoming occupy a 

significant geographic position in the regional stratigraphy of the Paleozoic Era in the northern Cordilleran 

region. This area was located close to the Transcontinental Arch during much of Paleozoic time and may 

have formed an emergent prong of the arch during part 

of that time (Sando, 1976b, fig. 1). Consequently, the 

Paleozoic sequence is composed largely of sedimentary 

rocks deposited close to ancient shorelines.

The original purposes of this study were to determine 

the lithology and paleontology of the Mississippian in 

the northern Laramie Range and adjacent areas 

(figs. 1, 2) and to correlate this sequence with Mississippian rocks studied previously in other parts of Wyoming. Because rocks at the base of the sequence originally referred to the Cambrian were later assigned 

tentatively to the Mississippian by some authors

l
PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

106° 105°

45'

illYellowstorfe

volcanic

area

Springs uplift\Wam8"tter 

arch

0 50 100 KILOMETERS 

FIGURE 1. Map of Wyoming showing present structural features (from Welder and McGreevy, 1966) and the area studied (shaded).

(Thomas, 1951; Maughan, 1963), the present study began at the top of the Precambrian. The study also included the lower part of the Casper and Hartville Formations (Pennsylvanian) in order to determine 

relationships with the Amsden Formation in areas to 

the north and west of the study area.

E.K. Maughan introduced the senior author to some 

of the localities studied during fieldwork in 1974. Most 

of the field studies were made by Sando, assisted by 

K.R. Moore. Conodont determinations are by Sandberg, foraminifer determinations are by B.L. Mamet of 

the Universite de Montreal, and other faunal determinations are by Sando. Harrison Sheng of the Department of Paleobiology of the Smithsonian Institution

advised Sando in heavy mineral identifications. Comments by J.T. Dutro, J.D. Love, J.E. Repetski, M.W. 

Reynolds, and G.L. Snyder significantly improved the 

original manuscript.

SUBJACENT ROCKS

The Paleozoic rocks of the northern Laramie Range 

rest unconformably on Precambrian granite that was 

not investigated thoroughly in this study. Where observed in the field, the granite is pink-weathering, 

poorly foliated, and composed mainly of pink orthoclase 

feldspar, biotite, and quartz in approximately equal
108

FREMONT CANYON SANDSTONE

107° 106°

Thermopolis

_ HOT ^PRINGS COUNTY!^^^*^^ ON COUNTY L CAMPBELL 

NA COUNTY 1 CONVERSE

WESTON ca

NIOBRARA 

COUNTY

I

NATRONA

BIGHORN MOUNTAINS I

,^Mounw.n :[:.steeple Pasture; :>s^\ _. "-^: ii^iiiyr

Fremont Canyon

CARBON" COUNTY"

0 10 20 30 40 KILOMETERS

FIGURE 2. Map of a part of southeast Wyoming showing location of stratigraphic sections discussed in this report. A-A' marks cross section 

illustrated in plate 1. Circled numbers mark locations of stratigraphic sections shown in figure 5.

grains 2-5 mm in diameter. Pegmatite veins are common. The rock commonly forms massive, rounded outcrops. A red weathered zone 1-5 ft (0.3-1.5 m) thick, 

probably a regolith, is present between the granite and 

overlying sedimentary rocks at Casper Mountain Road 

B (see section description).

In the Hartville uplift, the Paleozoic rocks rest unconformably on Precambrian dolomite, schist, and amphibolite, as well as on granite (G.F. Snyder, written 

commun., 1985). These rocks are assigned to the Late 

Archean Whalen Group (Smith, 1903; Hofmann and 

Snyder, 1985).

FREMONT CANYON SANDSTONE

DESCRIPTION

Cliff-forming quartz sandstone and quartzite that 

overlie the Precambrian granite and underlie the Englewood Formation (pi. 1) are referred to the newly 

named Fremont Canyon Sandstone (see discussion

below regarding nomenclature of this unit). The type 

section of this formation is at Fremont Canyon at the 

south end of Alcova Reservoir (see section description).

The basal contact of the Fremont Canyon Sandstone 

is an unconformity having a local relief of at least 1- 

2 ft (0.3-0.6 m) in the Laramie Range and as much as 

10 ft (3 m) in the Hartville uplift (G.F. Snyder, written 

commun., 1985). The top of the formation is sharp and 

without noticeable relief. The formation ranges in 

thickness from 6 ft (1.8 m) at Hartville Canyon to 

186 ft (56.7 m) at Fremont Canyon, but at Steeple Pasture it is absent.

The main body of the Fremont Canyon is classified 

petrographically as quartzarenite as used by Pettijohn, 

Potter, and Siever (1972). The rock consists of 95 percent or more of very angular to well-rounded, moderately well sorted quartz grains of predominantly very 

fine to coarse size. Feldspars, including orthoclase, plagioclase, and microcline, constitute 1 percent or less of 

the rock. The heavy mineral fraction constitutes 1 percent or less of the rock and consists predominantly of
PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

rounded to well-rounded black tourmaline. Other detrital minerals, in order of approximate decreasing abundance, are muscovite; pink, amber, yellow, and green 

tourmaline; zircon; pyroxene; magnetite; biotite; metamorphic and igneous rock fragments; and various 

metallic oxide and sulfide minerals. The cement consists predominantly of silica, but hematite and 

limonite are common as cementing materials.

The quartzarenite is friable to indurated and weathers white, gray, tan, orange, red, and pink. Current 

ripples and crossbedding in sets 0.1-2 ft (0.03-0.6 m) 

thick characterize most of the bedding. A distinctive 

feature is thin interbeds and partings of dessicationcracked, micaceous, silty, sandy clay shale weathering 

mostly grayish green. The detrital mineral fraction in 

the shale is essentially the same as that in the 

quartzarenite.

In the Laramie Range, the lower 3 to 20 ft (0.9- 

6.1 m) of the formation consists of subarkosic quartz 

sandstone and sandy conglomerate containing granite 

pebbles near the base. In the Hartville uplift, the basal 

beds commonly consist of angular fragments of quartz 

derived from underlying Precambrian dolomite and cemented by silica and hematite (G.F. Snyder, written 

commun., 1985). Clastic dikes of this material may extend downward into the Precambrian dolomite commonly tens of feet and locally a hundred feet.

The only fossils observed in the Fremont Canyon 

Sandstone are linear ichnofossils on bedding planes of 

shaly partings. Negative results were obtained from 

123 samples from throughout the unit processed for 

conodonts and 12 samples processed for palynomorphs.

AGE AND CORRELATION

PREVIOUS STUDIES

The sandstone in the Laramie Range herein referred 

to the Fremont Canyon Sandstone was regarded as the 

Deadwood Formation of Late Cambrian and Early Ordovician age by most previous workers. However, 

Thomas (1951, p. 32) briefly described the stratigraphy 

of the Cambrian sandstones southwest of the study 

area and suggested that the Cambrian rocks pinch out 

eastward, just east of the Shirley Mountains, before 

reaching the Laramie Range. He (p. 34) also pointed 

out localities in the Laramie Range and vicinity where 

Mississippian fossils were found in or just above a sandstone that rested on the Precambrian granite.

Love, Henbest, and Denson (1953) correlated sandstone underlying the Guernsey Formation and overlying the Precambrian granite with the sandstone in the 

Laramie Range and assigned it questionably to the 

Cambrian.

Maughan (1963) compiled evidence for a Mississippian age for thin sandstone overlying Precambrian 

granite in the Laramie Range south of the study area 

and questioned the Cambrian age of the sandstone 

found in the northern Laramie Range and adjacent 

areas. He included the sandstone of the study area on 

his isopach map of the basal Mississippian sandstone.

PRESENT ANALYSIS

The nearest possible correlatives to the quartz sandstone at the base of the Paleozoic sequence in the area 

studied are the Deadwood Formation (Upper Cambrian 

and Lower Ordovician) of South Dakota, the Sawatch 

Quartzite (Upper Cambrian) of Colorado, the Harding 

Sandstone (Middle Ordovician) of Colorado, the Winnipeg Sandstone (Middle Ordovician) of North Dakota, 

the Lander Sandstone Member of the Bighorn 

Dolomite (Upper Ordovician) of western and northern 

Wyoming, and the Parting Formation (Upper Devonian) of Colorado (fig. 3). These are all partly or predominantly supermature, multicyclic quartzarenites 

distinguished from each other with difficulty in places 

where stratigraphic position and paleontology are unknown. Each of these sheet sands probably covered an 

area much larger than that indicated by their present 

distribution, which resulted from several periods of uplift and erosion prior to the present. In the absence of 

paleontologic data to determine the age of the sandstone of the study area, physical criteria were used to 

compare this sandstone to formations previously established in the northern Cordilleran region (table 1.)

The Deadwood Formation has been recognized in a 

large area that includes parts of western North and 

South Dakota and eastern Wyoming (fig. 3). Correlation with the Deadwood Formation fails chiefly because of the lack of glauconite in the sandstone of the 

study area. Pettijohn, Potter, and Siever (1972, p. 229) 

state that glauconitic sandstones are particularly common in the Cambrian. Thomas (1951, p. 34) noted that 

the upper part of the Deadwood is commonly glauconitic, and Carlson (1960, p. 33) also described the 

Deadwood as glauconitic. Thus, it would seem that 

glauconite is a reliable index to the Deadwood. Moreover, the Deadwood contains invertebrate fossils of 

Late Cambrian and Early Ordovician age (Meyerhoff 

and Lochman, 1934,1935,1936; Lochman and Duncan, 

1950; Miiller, 1956; Ross, 1957a; Carlson, 1960) and 

fish remains (Repetski, 1978), whereas no such fossils 

were found in the sandstone of the study area. The 

Deadwood Formation also lacks the dessication cracks 

and green, micaceous, shaly partings found in the sandstone of the study area. Carbonate interbeds are common in the Deadwood but absent in the unit studied.
FREMONT CANYON SANDSTONE

".-".x -NORTH DAKOTA iL-.-^ 

*" SOUTH DAKOTA.::: :"

 Lander Sandstone : '. : .' ; : ;.'. - .'-' '

.v-nT.-v ":' : - ' - .- -'-Til ; :-.-.T~ _L^/^i NENEBRASKA 

COLORADO I

£}§>:'.0;-:^

EXPLANATION

Upper Devonian sandstone 

Upper Ordovician sandstone 

Middle Ordovician sandstone

Lower Ordovician and Upper Cambrian 

sandstone

Exposed Precambrian crystalline rocks

FIGURE 3. Traditional restored distribution of quartz sandstones of Late Cambrian and Early Ordovician, Middle and Late Ordovician, and Late Devonian ages in the northern Cordilleran region. Data 

from Richards and Nieschmidt (1957), Ross (1957b), Lochman-Balk (1972), Foster (1972), and Baars 

(1972).
6 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

TABLE 1. Characteristics of Cambrian to Devonian quartz sandstones in the northern Cordilleran region

[References: Deadwood (Thomas, 1949; Block, 1952; Chronic and others, 1969; Carlson, 1960); Harding (Tolgay, 1952; Chronic and others, 1969; J.D. Love, written commun., 1985);

Winnipeg (Carlson, 1960); Parting (Campbell, 1970, 1972); Fremont Canyon (this paper)]

Characteristic Deadwood 

Formation Harding Sandstone Winnipeg Formation Parting Formation Fremont Canyon 

Sandstone

Petrographic classification 

Mean grain size (approximate)

Orthoquartzite

Medium-coarse Very fine sand Very fineRoundness of sand grains ------------

Mature heavy mineral suite 1% of rock 

Glauconite --------------------------

Phosphate grains --------------------

sand

Well rounded 

?

X

medium sand

Basal arkosic conglomerate, poorly - - - 

sorted.

Well rounded 

X

Rounded

X

Orthoquartzite- Quartzarenite 

subgraywacke

Mediumcoarse sand

? 

X

coarse 

sand

Well rounded 

X

X

Carbonate and (or) shale interbeds - - - X 

X 

X 

X

9 ----------------

X X 

X X

X 

X

X 

X

X 

X

X

The Harding Sandstone is known mainly from outcrops in central Colorado, but was also described from 

diatremes at the south end of the Laramie Range 

(Chronic and others, 1969) and from a few localities in 

the Bighorn Mountains (Kirk, 1930; Hose, 1955) 

(fig. 3). The Harding contains Middle Ordovician 

conodonts (Sweet, 1955) and fish remains (Walcott, 

1892; 0rvig, 1958; Chronic and others, 1969), which 

distinguish it from the barren sandstone of the study 

area. Phosphate grains, noted by Chronic and others 

(1969) in the Harding, are also absent from the unit 

studied. The Harding also contains thick shale interbeds not present in the study area.

The Lander Sandstone Member of the Bighorn 

Dolomite consists of light-greenish-gray and pinkishgray sandstone containing shaly streaks, laminae, and 

nodules. It contains an Ordovician shelly fauna including orthocones, gastropods, and Receptaculites. Its 

open-marine origin is so obvious that its characteristics 

are not tabulated in table 1.

The Winnipeg Sandstone is recognized in the subsurface of eastern Montana, northeastern Wyoming, and 

western North and South Dakota and in outcrop in 

northeastern Wyoming (fig. 3). Like the Harding, the 

Winnipeg contains a diverse Middle Ordovician 

conodont fauna (e.g., Carlson, 1960; Sweet, 1982) and 

considerable amounts of shale, features absent in the 

sandstone of the study area. Moreover, the Winnipeg 

Sandstone does not have the crossbedding, dessication 

cracks, and green micaceous shale partings of the unit 

studied.

The Parting Formation occupies a relatively small 

area in central Colorado (fig. 3). It consists of a complex 

sequence of quartz sandstone, shale, and dolomite 

(Sandberg and Poole, 1977, fig. 15) but is almost entirely sandstone at some localities (Campbell, 1970). 

The sandstone includes predominantly medium- to 

very coarse-grained and conglomeratic orthoquartzite 

(quartzarenite), protoquartzite, feldspathic sandstone 

(subarkose), and subgraywacke (Campbell, 1972). The
ENGLEWOOD FORMATION

accessory mineral suite includes zircon, tourmaline, 

muscovite, biotite, and chert grains. Silica is the predominant cement. Interbedded shales are green, micaceous, and arenaceous. The sandstone is crossbedded. 

The Parting is dated by conodonts as Late Devonian 

(late Famennian) and contains the Upper postera and 

Lower expansa Zones (Sandberg and Dreesen, 1984, 

fig. 5).

Close petrographic similarity of the sandstone of the 

study area with the Parting Formation (table 1) and its 

similar stratigraphic position leads us to the conclusion 

that the unit studied is probably correlative with and 

approximately the same age as the Parting. The sandstone in Wyoming cannot be physically traced into the 

area of the Parting in Colorado, and the absence of 

diagnostic fossils in the study area precludes precise 

biostratigraphic correlation. For these reasons, the 

strata in Wyoming are given a new name.

The lack of an obvious discontinuity between the 

sandstone unit and the overlying Englewood 

Formation, which has been dated by conodonts as Late 

Devonian (Lower to Middle expansa Zone) and Early 

Mississippian in the study area, provides compelling 

circumstantial evidence for a Late Devonian age for the 

basal sandstone. Moreover, the upper part of the Parting of Colorado and the basal part of the Englewood of 

the study area contain conodonts that belong to the 

same conodont zone. Where the contact is well exposed 

(e.g., Casper Mountain Road, Banner Mountain, Box 

Elder Canyon), the plane of contact shows little or no 

relief and is marked mainly by a general reduction in 

size of siliceous grains from the Fremont Canyon to the 

overlying Englewood Formation (pi. 2). Sandstone beds 

in the Englewood are very similar in grain size, heavy 

mineral suite, and sedimentary structures to those in 

the Fremont Canyon Sandstone. Supporting evidence 

for the Devonian age of this sandstone is supplied by 

three paleomagnetic pole determinations made by 

S. Beske-Diehl (written commun., 1975) from samples 

collected in the Casper Mountain Road B section (see 

section descriptions). These determinations suggest a 

pole position closer to that of the Devonian than to 

Cambrian and Ordovician pole positions.

The areal extent of the Fremont Canyon Sandstone is 

not completely documented, but sandstone of similar 

lithology and stratigraphic position has been reported 

by Thomas (1951) in the Seminoe Mountains, Elk 

Mountain, and western Laramie Range; by Love, 

Henbest, and Denson (1953) in the Hartville area (we 

also recognize it there); by Love, Denson, and Botinelly 

(1949) in the Glendo area; by Lageson (1977) in the 

northern Medicine Bow Mountains; by Mytton (1954)

in the study area; by Ritzma (1951) in the Washakie 

basin and the Sierra Madre; and by Maughan (1963) 

over much of the southeast Wyoming and parts of western Nebraska and northeast Colorado. The occurrence 

of Mississippian fossils in thin sandstone sequences at 

some localities in southern Wyoming suggests that 

some of these beds actually belong to the overlying 

Englewood Formation, which is not readily distinguishable lithologically from the Fremont Canyon 

where only a few feet of sandstone is present above the 

Precambrian. Figure 4 shows a revised interpretation 

of the distribution of Upper Devonian sandstone based 

on the present analysis and on relationships with older 

sandstones in the northern Cordilleran region. The 

present distribution of Upper Devonian sandstone, like 

that of older sandstones, is probably only an erosional 

remnant of a formerly larger areal extent.

ORIGIN

According to Campbell (1970), the sandstone of the 

Parting Formation in central Colorado represents 

nearshore marine environments and was derived 

mostly from the "Front Range highland," an area of 

moderate relief composed of metamorphic, igneous, and 

some older Paleozoic sedimentary rocks. Conodonts in 

the Parting are assigned to the clydagnathid biofacies, 

which is within the most nearshore of the Devonian 

facies belts and indicates restricted marine to peritidal 

environments (Sandberg and Dreesen, 1984). A similar 

origin is indicated for the Fremont Canyon Sandstone 

in the area studied. The broad distribution of this sandstone (fig. 4) suggests derivation from the Transcontinental Arch to the east of the area studied.

ENGLEWOOD FORMATION

DESCRIPTION

Poorly resistant terrigenous and dolomitic rocks that 

ordinarily overlie the Fremont Canyon Sandstone and 

underlie the Madison Limestone are referred to the 

Englewood Formation (pis. 1,2). The basal contact with 

the Fremont Canyon Sandstone is sharp, without noticeable relief, and is placed at the base of the lowest 

red siltstone above the quartz sandstone of the Fremont 

Canyon. However, at Steeple Pasture (see section descriptions), the formation rests unconformably on Precambrian granite. The upper contact with the Big 

Goose Member of the Madison Limestone is sharp and 

without noticeable relief. The top of the Englewood is
PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

______ y\ -:' .'_'.Vf.:'';:-'^-.'.'.I'.-.";'. : : . .' .' /: peadyvood Formation ' ; .' ." .' :; : '.".'. 

[Winnipeg jr^\^'-\' '-.' !'' ":'.' /. : j'-'-'-.'-'.-: ' ':. ' " '-'. .-.'.' V-' ': ' ".''." ' ' ':: ;;/:' :' " '!.-' ' '' ': ': ':' ' .'.'.'.'

Lander Sandstone 

Member of Bighorn 

Dolomite and

Harding (?) Sandstone

 ;: Deadwood . . . .].';

: -' _Formation : '-' '. ''. W.'-.'^>

...-...v..-.:-. .... ..

Fremont Canyon Sandstone 

and Englewood Formation

K

NEBRASKA 

COLORADO|

awatchV-'.-:; : . .' :." ' '.-\\'.' '.:-. ." / .' '.' ':.' ' ' ' ' ! ' ' ' ' ' .'.' ' .''."'.'! .' ' ' '.' ' '.'.'.' '.'/ 

£ ^£[H!!fA- " ''.' '.' / ' '.' '.'' '' ' '.-'.' ' ' ' ' v.' ' '.' ' '-V-v.v /.! ' '.' .' :'. ':/'.' ' .' . ' .' .' .' .' ' '.' '- ." ' ' ' /

\-;|:.:.-;:.;;.:g::;--y:-:::;-^v^p

^s§p;^^^|;^;^p..

.-:.' i-'.-'.-y.'-'.' _' ;:': ' .-.V^^P'.\' .' Sandstone '. .' " 

10 50 100 MILES

i ____i

0 50 100 KILOMETERS

EXPLANATION

Upper Devonian sandstone 

Upper Ordovician sandstone 

Middle Ordovician sandstone

[ .' /.' .vI Lower Ordovician and Upper Cambrian 

'' ' ' ' I sandstone

Exposed Precambrian crystalline rocks

FIGURE 4. Revised, partly restored distribution of quartz sandstones of Late Cambrian and Early Ordovician, Middle and Late Ordovician, and Late Devonian ages in the northern Cordilleran region 

based on revised interpretation of sandstones in southeast Wyoming. Maughan's (1963) data were 

used in areas of southeast Wyoming not studied by the authors.
ENGLEWOOD FORMATION

TABLE 2. Diagnostic Devonian and Mississippian conodonts from the Englewood Formation

[See pi. 2 for positions in measured sections. Numbers are numbers of specimens. X denotes presence only]

Locality and USGS Upper Paleozoic catalog number (Sandberg collection number)

Taxon and age Fremont Canyon Casper Mountain Banner Mountain

25976-PC 25975-PC 25879-PC 25878-PC 26008-PC (BAH-3) (BAH-2)

Box Elder Canyon

26036-PC

Kinderhookian

Pandorinellina n. sp. -----------

Patrognathus andersoni (crenulata 

Zone or younger)

Polygnathus inornatus

P. inornatus rostratus

P. longiposticus

Siphonodella sp. 

Late Devonian

Lower or Middle expansa Zone - - 

Icriodus costatus ? ----------

Polygnathus communis carina 

P. experplexus --------------

P. semicostatus -------------

P. sp. ----------------------

Lower expansa Zone

Clydagnathus ormistoni ----- 

Polygnathus semicostatus --- 

Scaphignathus sp. ----------

igei ) --------------- ------- ...

o q v

------- ------- Y

14

9

QQ

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

placed at the top of dolomitic or terrigenous rocks beneath thin-bedded cherty dolomicrite of the Big Goose 

Member of the Madison (pi. 2). The formation ranges in 

thickness from 12.7 ft (3.8 m) at Steeple Pasture to 

44.8 ft (13.8 m) at Banner Mountain. The Englewood is 

weakly resistant and ordinarily covered or poorly exposed; the best exposure is in road cuts at the Casper 

Mountain Road B section.

The Englewood Formation consists predominantly of 

quartz siltstone, very fine- to fine-grained quartz sandstone, and silty and sandy dolomicrite that weather 

red, brown, and orange in platy beds 0.1-0.5 ft (0.03- 

0.15 m) thick and thin interbeds and partings of greenweathering silty and sandy clay shale. The formation 

also contains beds of medium-grained quartz sandstone 

that in a few places are conglomeratic and crossbedded, 

0.3-1 ft (0.09-0.3 m) thick, and that weather white, 

brown, and red. Dessication cracks and salt casts also 

occur rarely.

The sandstone beds are poorly to well-sorted 

quartzarenites composed of as much as about 95 percent or more very angular to subrounded quartz grains 

and containing rare detrital grains of plagioclase, orthoclase, microcline, muscovite, tourmaline, and crystalline rock fragments. The cement is silica, calcite, 

dolomite, and limonite.

FOSSILS, AGE, AND CORRELATION

The Englewood Formation of the area studied is similar in lithology and age to the Englewood Formation of 

the Black Hills in South Dakota as described by Klapper and Furnish (1962) and by Sandberg (1963, p. C20). 

Sandberg and Mapel (1967, fig. 10) projected this formation into southeast Wyoming from its principal area 

of occurrence in the northeast. Beds of similar lithology, age, and stratigraphic position were included in 

the basal part of the Guernsey Formation in the Glendo 

and Hartville areas by Smith (1903), Love, Denson, and 

Botinelly (1949), and Love, Henbest, and Denson 

(1953).

Conodonts are the only identifiable fossils recovered 

from the Englewood Formation in the area studied. The 

conodont assemblages (table 2) are generally meager, 

of low diversity, and contain elements characteristic of 

shallow-water faunas. Assemblages of two ages can be 

recognized in the samples from the Englewood: Kinderhookian assemblages probably correlative with the duplicata, sandbergi, and Lower crenulata Zones (see 

Sandberg and others, 1978), and Late Devonian assemblages characteristic of the Lower or Middle expansa 

Zone (see Ziegler and Sandberg, 1984).
10 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

The top of the Englewood Formation is placed at the 

base of the lowest cherty, nonsandy dolomicrite in the 

Big Goose Member of the Madison (pi. 2). This contact 

is not exposed at Fremont Canyon, Casper Mountain 

TV Tower, and Box Elder Canyon. However, at Fremont Canyon, Casper Mountain Road B, Banner 

Mountain, and Steeple Pasture, the highest bed in the 

Englewood is noncherty, crinoidal, ordinarily sandy 

biomicrite that contains Kinderhookian conodonts. 

This bed overlies a disconformity between Kinderhookian and Upper Devonian rocks, except at Banner 

Mountain, where a 1.3-ft-thick (0.4-m-thick) bed of 

quartz sandstone occurs between the dolomite and the 

disconformity, and at Casper Mountain Road B, where 

a siltstone bed 1.5 ft (0.5 m) thick occurs between the 

dolomite and the disconformity. Thus, the uppermost 

part of the Englewood contains Mississippian strata 

equivalent to the upper tongue of the Cottonwood 

Canyon Member of the Madison Limestone of northcentral Wyoming (see Sandberg and Klapper, 1967, 

and Sandberg and Mapel, 1967), and the lower part of 

the Englewood contains strata equivalent to the lower 

tongue of the Cottonwood Canyon Member.

The Englewood Formation probably has a much 

wider distribution, although erratic, in southern Wyoming than formerly recognized. An 8-ft (2.4-m) interval 

of red-weathering quartz siltstone, sandstone, and conglomerate previously included in the basal Madison at 

Buck Spring in the Rawlins Hills (Sando, 1967, fig. 3; 

1979, fig. 3) is now recognized as Englewood Formation 

(fig. 5, locality 2). Likewise, beds of red-weathering 

sandstone and sandy limestone in the same stratigraphic position at Cottonwood Creek in the Ferris 

Mountains (Sando, 1979, fig. 3) are now also placed in 

the Englewood (fig. 5, locality 3). Conodont samples 

from the basal 1.5 ft (0.5 m) of the Englewood at Cottonwood Creek collected by M.W. Reynolds yielded large 

conodont faunas that belong to the PatrognathusPandorinellina biofacies of the Kinderhookian Lower 

crenulata Zone. Other possible occurrences of the formation are terrigenous rocks resting on the Precambrian granite from which Mississippian fossils were 

reported by Thomas (1951, p. 34) in the subsurface 

south of Rawlins, the Seminoe Mountains, and on the 

west flank of the Laramie Range. The Englewood Formation is probably also present at some of the localities 

summarized by Maughan (1963) in the Laramie Range 

and elsewhere in southeast Wyoming. The terrigenous 

and dolomitic interval included in the basal part of the 

Guernsey Formation in the Glendo area by Love, Denson, and Botinelly (1949) and in the Hartville uplift by 

Love, Henbest, and Denson (1953) certainly includes 

beds that we regard as belonging in the Englewood

Formation, particularly that part of the interval from 

which Devonian fossils were recovered. The upper 

Famennian conodont Polygnathus obliquicostatus 

Ziegler (identified by B.R. Wardlaw) was recovered 

from this unit on the north side of Sparks Canyon in the 

Hartville uplift (G.F. Snyder, written commun., 1985, 

sample 2225). The Fremont Canyon Sandstone is also 

present at the base of the interval in much of the 

Glendo-Hartville area (see our Hartville Canyon section, fig. 5, locality 6, and section descriptions). Differentiation of these two Devonian terrigenous units is 

difficult where they are both thin, requiring lumping of 

the two formations in a single map unit in some areas 

(see geologic maps accompanying section descriptions).

ORIGIN

Similar mineralogy of the sandstone beds in the 

Englewood Formation and the Fremont Canyon Sandstone suggests similar sources for the detritus. These 

sandstones had a comparable peritidal origin, probably 

on beaches. Dessication cracks and salt casts in the 

siltstones of the Englewood Formation indicate an intertidal or supratidal flat environment.

MADISON LIMESTONE

DESCRIPTION AND DISCUSSION

Carbonate rocks that conformably overlie the Englewood Formation and that are disconformably overlain 

by the Casper and Hartville Formations are referred to 

the Madison Limestone (Peale, 1893). In the study 

area, the Madison is a formation that consists of three 

members, which are, in ascending order, the Big Goose 

Member (Sando, 1982; formerly cherty dolomite member of Sando, 1972), the Little Tongue Member (Sando, 

1982; formerly cliffy limestone member of Sando, 

1972), and the Bull Ridge Member (Sando, 1968). The 

type section for the lower two members is in the 

Bighorn Mountains, and the type section for the upper 

member is in the Wind River Mountains. All three 

members have been traced over a large area in northcentral Wyoming and southern Montana, where they 

have been studied in the Beartooth Mountains (Sando, 

1972), Absaroka Range (Sando, 1975), Washakie 

Range (Sando, 1967), Gros Ventre Range (Sando, 

1977), Wind River Range (Sando, 1967, 1968), Owl 

Creek Mountains (Sando, 1967), and Bighorn Mountains (Sando, 1976a). Sando (1979) summarized the 

stratigraphy of the Madison Limestone in Wyoming 

and recognized the three members of the Madison in 

the northern Laramie Range.
MADISON LIMESTONE 11

SYSTEM

NORTH AMERICAN PROVINCIAL SERIES

EUROPEAN WESTERN 

STAGES

ZONES FORAMINIFER ZONES CNODONT 

OVERLYING ROCKS

MISSISSWPIAN (PART)

MERAMECIAN 

"° OSAGEAN (PART)

KINDERHOOKIAN

UPPER DEVONIAN 

(PART)

(PART) VISEAN 

TOURNAISIAN

LU Z 

L^Z

12

11

10

9

8

7

cc

Q.

UNZONED

1 2 

CO II 1

z Southern Raw ins 

O Wind River H Ms 

_, Mountains (Buck 

< (Sweetwater Spring) 

§ Canyon)

O

Horseshoe Sha e Darw n Sandstone 

Member of Member of 

Amsden Format on Amsden Formation 

(Chester an (Chester an

texanus

anchoralis-latus

typicus

isostichaUpper 

crenulata

U 

L

Lower crenulata

sandbergi

duplicata

sulcata

praesulcata

expansa

UNDERLYING ROCKS

U 

L

_y_

T

U 

JVL

III

II

I

B 

A

L ttle ° Little 

Tongue Tongue 

Member Member

= 11 

1 I

'3 > 

c Big Goose c B g Goose 

§ Member g Member

lo ~m 

A 5 5

C

B Englewood 

Formation 0

A

O

LU

Z

o

z

Bighorn Buck Spring 

Dolomite Formation 

(Ordov c an) (Cambr an

345

Ferris Southern Northern 

Mounta ns Bghorn Laramie 

(Cottonwood Mountains Range 

Creek) (Blue (Composite) 

Creek) of 6 sect ons, 

this report)

Darwin Sandstone Darw n Sandstone Darw n Sandstone 

Member of Member of Member of 

Amsden Formation Amsden Format on Casper Format on 

(Chester an (Chester an (Pennsylvan an

1

Lttle !little Lttle Q 

Tongue Tongue *O« Tongue o 

Member Memb,er = Member O

7 OT

| B g Goose | ° 

H o> Member j

S ! * J c Big Goose £ Woodhurst g B g Goose 

g Member !3 Member 5 Member

1 1-DO*

Little 

i Biahorn

_ . . Member J Englewood X

Formation x x« v

Upper Vi 

o part /

£

 Q

t 

HI

Lower part x

Buck Spring Gallatin Fremont Canyon 

Formation L mestone Sandstone 

(Cambrian (Cambrian (Devonian

6

Hartville 

uplift 

(Hartville 

Canyon)

Darw n Sandstone 

Member of 

Hartville Format on 

(Pennsylvan an

Lttle 

Tongue 

Member

Limestone Madison (

S5I? o Z

c 

o

£ 

1

HI

Lower part

Fremont Canyon 

Sandstone 

(Devonian)

FIGURE 5. Correlation of Upper Devonian and Mississippian sequences at selected localities in southern Wyoming (see fig. 2 for locations). 

Conodont zonation slightly modified from Sando, Sandberg, and Gutschick (1981), and Ziegler and Sandberg (1984). Foraminiferal zonation 

from Mamet in Sando, Mamet, and Dutro (1969). Coral zonation from Sando and Bamber (1985). Fossil collections indicative of corresponding 

zone at left; open circle, foraminifers; x, conodonts; closed circle, corals.

Throughout most of north-central Wyoming and 

southern Montana, the Madison includes three additional members beneath the Big Goose Member. These 

are, in ascending order, the Cottonwood Canyon Member (Sandberg and Klapper, 1967), the Little Bighorn 

Member (Sando, 1982; formerly lower dolomite member of Sando, 1972), and the Woodhurst Member (Weed, 

1899). In the northern Laramie Range and vicinity, 

time equivalents of these lithologic units are present in 

the Englewood Formation and the Big Goose Member.

whose base is much older than elsewhere in its area of 

occurrence.

On plate 1, sections in the study area are correlated 

to the Blue Creek section in the southern Bighorn 

Mountains to show the stratigraphic relationships of 

the three members of the Madison that are present in 

both areas and the time equivalence of the lithologically dissimilar lower part of the Madison. Madison 

sequences more generally similar in the lower part to 

that of the northern Laramie Range occur in the south-
12 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

ern Wind River Mountains, Ferris Mountains, Rawlins 

Hills, and Hartville uplift (fig. 5).

STATUS OF GUERNSEY FORMATION

The name "Guernsey Formation" was introduced by 

Smith (1903, p. 2) to include strata between the Precambrian rocks of the Whalen Group and the Casper 

Formation (Pennsylvanian and Permian) in the 

Hartville quadrangle. Smith's nomenclature was perpetuated by Love, Denson, and Botinelly (1949) in their 

mapping of the Glendo area and by Love, Henbest, and 

Denson (1953) in the Hartville uplift. Although no type 

section was designated, Smith briefly described a 

stratigraphic section measured "near Fairbank" to 

show "the general character of the beds composing the 

formation." Our Hartville Canyon section (see pi. 1, 

fig. 5, and section descriptions) was measured at a location just north of the location shown for the town of 

Fairbank on Smith's (1903) geologic map and conforms 

to his description of the lithology of the Guernsey. We 

consider this section the type section of the Guernsey 

Formation.

The present investigation indicates clearly that the 

basal part of the Guernsey, as originally defined, includes beds now assigned elsewhere to the Fremont 

Canyon Sandstone and the Englewood Formation. The 

remainder of the type Guernsey is readily classified as 

Big Goose and Little Tongue Members of the Madison 

Limestone. Thus, the Guernsey is a superfluous name 

and is replaced in this report by the Madison Limestone, Englewood Formation, and Fremont Canyon 

Sandstone.

BIG GOOSE MEMBER

DESCRIPTION

The Big Goose Member is the oldest member of the 

Madison Limestone in the study area. It generally 

overlies the Englewood Formation conformably and is 

conformably overlain by the Little Tongue Member of 

the Madison, but it rests directly on Precambrian 

dolomite near Hell Gap in the Hartville uplift (G.F. 

Snyder, written commun., 1985). The thickness of the 

Big Goose Member ranges from 87 ft (26.6 m) in the 

Casper Mountain TV Tower section to 206 ft (63 m) at 

Steeple Pasture. The member thickens both eastward 

and westward from Casper Mountain (pi. 1).

The Big Goose Member consists predominantly of 

cherty, thin-bedded, fine-grained, commonly intensely 

fractured (but rarely brecciated) dolomite and 

dolomitic limestone that weather mostly yellowish 

gray. Petrographically, the dominant rock type is

dolomicrite. Chert occurs as brown, gray, and white 

irregular nodules and stringers that parallel bedding 

and may constitute 5 to 40 percent of the dolomitic beds 

in the member. Faint lamination is a common feature 

in the dolomitic beds, and some of the laminations appear to represent stromatolites. Medium- to coarsegrained, crossbedded, bioclastic (molds and casts) 

dolomitic limestone and dolomite are present in the 

lower part of the member at some localities. Grayweathering, mostly fine-grained, commonly cherty 

limestone in beds as much as 2 ft (0.6 m) thick is interbedded with the dolomitic beds in the upper part of 

the member at most localities. The limestone includes 

fossiliferous and unfossiliferous micrite (commonly 

laminated), biomicrite, and pelmicrite, and rare pelbiosparite, pelsparite, and intrabiosparite. Some of the 

limestone beds are partly recrystallized. Stromatolites 

are rare.

FOSSILS, AGE, AND CORRELATION

Fossils are rare in the Big Goose Member. Algal cysts 

(calcispheres), stromatolites, crinoid debris, brachiopods, bryozoans, and coral fragments are sporadically distributed throughout the member in the sections studied. Vesiculophyllum, a very common 

Mississippian coral, was found near the middle of the 

member at Steeple Pasture. Foraminifers and algae of 

Mamet Zone 8 (near top of zone), indicative of an Early 

Mississippian (middle Osagean) age, were collected at 

the top of the member in the Casper Mountain TV 

Tower section.

Extensive sampling for conodonts resulted in discovery of only five identifiable assemblages from the lower 

20 ft (6.1 m) of the member at three localities (table 3, 

pi. 2). These assemblages are all of Early Mississippian 

(Kinderhookian) age and represent shallow-water biofacies not readily assignable to standard conodont 

zones. However, conodonts in USGS 26013-PC belong 

to the Patrognathus-Pandorinellina biofacies and indicate the Lower crenulata Zone or the isosticha -Upper 

crenulata Zone.

Foraminiferal and conodont data indicate an age 

range of Kinderhookian to middle Osagean for the Big 

Goose Member in the study area. This means that most 

of the member here is older than it is throughout most 

of north-central Wyoming (see Sando, 1979, fig. 3). In 

fact, the Big Goose here includes time equivalents of 

the upper part of the Cottonwood Canyon Member, the 

Little Bighorn Member, and the Woodhurst Member, 

which make up the lower part of the Madison Limestone in the Bighorn Mountains, Washakie Range, Absaroka Range, northern Wind River Range, and Gros
MADISON LIMESTONE 13

Ventre Range. The base of the Big Goose in the study 

area is also slightly older than it is in the Rawlins 

Hills, southern Wind River Range, and Ferris Mountains (fig. 5).

ORIGIN

The lithic facies of the Big Goose Member overwhelmingly indicate shallow-water, nearshore, marine 

environments. The main lithologies are fine-grained 

dolomite and limestone (dolomicrite and micrite) suggestive of deposition in relatively quiet waters, probably in lagoons or on intertidal mudflats. The presence 

of stromatolites and the rarity of marine fossils support 

these conclusions. Although no evaporitic rocks were 

found in the member, abundant autobrecciation (fracturing) of the dolomites suggests leaching of thin evaporite layers from an evaporitic carbonate sequence, 

which is consistent with postulated shallow lagoonal 

environments.

Chronostratigraphy indicates that the Big Goose 

Member in the northern Laramie Range represents the 

lower part of an extensive lithosome extending over 

much of southern Wyoming (fig. 5). This lithosome was 

marginal to an emergent or near-emergent prong of the 

Transcontinental Arch now represented by outcropping plutonic and metamorphic rocks of the core of the 

Laramie Range uplift in southeast Wyoming. The 

lower part of the Big Goose lithosome extended westward to at least the longitude of the southern Wind 

River Mountains, eastward for some unknown distance

TABLE 3. Diagnostic Kinderhookian conodonts from the Big Goose 

Member of the Madison Limestone

[See pi. 2 for positions in measured sections. Numbers are numbers of specimens]

Locality and USGS Upper Paleozoic catalog number

Taxon Casper Mountain 

RoadB

Banner Steeple 

Mountain Pasture

25883-PC 25882-PC 25880-PC 26009-PC 26013-PC

Bispathodus

B. stabilis ----- ------- ......

Hindeodus cf.

H. cristulus - ------- ------

Pandorinellina

plumula ---- ------- ------

P. n. sp. ------ ------- .--.--

Patrognathus

andersoni --- 1 5

Polygnathus

inornatus --- ------- --....

Siphonodella

advanced

Sp. -.-.-.-.. ....... ......

9

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

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

....... ...... 5

1 ------ 2

....... i 9

....... i 3

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

into Nebraska, and northward into the Wind River and 

Powder River basins. Northward, the lower part of the 

Big Goose lithosome interfingered with carbonate 

rocks deposited in slightly deeper waters of the Wyoming Shelf. Exposures of these seaward rocks in the 

lower part of the Madison Limestone in the Washakie 

Range, Owl Creek Mountains, and Bighorn Mountains 

are probably just north of the northern edge of the 

lower part of the Big Goose lithosome. The Wind River 

Mountains transect the boundary and provide exposures of it. Later in Osagean time, the Big Goose lithosome extended northward as a tongue into rocks deposited in deeper waters in southern Montana.

LITTLE TONGUE MEMBER

DESCRIPTION

The Little Tongue Member conformably overlies the 

Big Goose Member of the Madison. At Fremont Canyon 

and Casper Mountain, the Little Tongue Member is 

overlain conformably by the Bull Ridge Member of the 

Madison, but at Steeple Pasture and Box Elder 

Canyon, the Bull Ridge Member was removed by 

post-Madison, pre-Casper erosion and the Little 

Tongue is overlain unconformably by the Darwin 

Sandstone Member of the Casper Formation. At 

Hartville Canyon, the Little Tongue is overlain unconformably by the Darwin Sandstone Member of the 

Hartville Formation. The thickness of the Little 

Tongue Member ranges from 50 ft (15.3 m) in the 

Casper Mountain TV Tower section to 93.5 ft (28.6 m) 

at Fremont Canyon (pi. 1). The member thickens both 

eastward and westward from Casper Mountain.

The lower 13 to 30 ft (4-9.1 m) of the Little Tongue 

Member constitutes the lower solution zone, an informal stratigraphic unit that consists of carbonate solution breccia produced by leaching of evaporite beds 

(Sando, 1974). The breccia consists of poorly bedded, 

angular fragments of limestone, fine-grained dolomite, 

and chert as much as 1 ft (0.3 m), but mostly 0.3 ft 

(0.09 m) or less, in diameter in a matrix of fine-grained 

dolomite or calcareous rock flour, calcareous quartz 

siltstone, or fine-grained quartz sandstone. Bedded, 

platy, calcareous siltstone also occurs in the unit. The 

rocks weather mostly yellow, pink, and red. This unit is 

poorly exposed and forms a reentrant beneath a massive cliff at most localities.

The main body of the Little Tongue Member consists 

of gray-weathering, cliff-forming, cherty, mediumbedded limestone that overlies the lower solution zone. 

The limestone beds are fine to coarse grained and include micrite, pelmicrite, biomicrite, and intrabiosparite as well as grapestone biosparite, oosparite, and
14 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

oobiosparite. Biogenic grains include fragments of 

crinoids, brachiopods, foraminifers, bryozoans, gastropods, corals, and ostracodes. Brown chert lenses, 

nodules, and stringers that parallel bedding make up 

10-20 percent of the rock. The limestone beds are 

dolomitized at some localities.

Brecciation of the limestone owing to collapse of 

these beds into the underlying solution zone is evident 

at all localities. Rotated blocks of limestone as much as 

several feet in diameter are a common feature of the 

lower half the limestone unit, and undulant bedding is 

common in the upper part. Where the limestone is thin, 

the entire unit is brecciated.

FOSSILS, AGE, AND CORRELATION

Although no fossils were found in the lower solution 

zone of the Little Tongue Member, the limestone that 

makes up most of the member contains a moderately 

rich shelly benthonic fauna. Crinoidal debris is the 

most common organic material, but fragments of brachiopods, foraminifers, bryozoans, gastropods, corals, 

and ostracodes are also evident in thin sections of the 

limestone. Brachiopods of the Unispirifer madisonensis 

type are the most common fossils. The coral Vesiculophyllum was collected at the Casper Mountain TV 

Tower section. Mamet Zone 8 or 9 (late Osagean) 

foraminifers were found in the upper 32 ft (9.8 m) of the 

member at Fremont Canyon, and foraminifers probably representing Mamet Zone 9 (late Osagean) were 

found 2 ft (0.6 m) below the top of the member at 

Steeple Pasture.

A late Osagean age is indicated for the Little Tongue 

Member by late Osagean foraminifers found in the upper part and by the occurrence of middle Osagean 

foraminifers at the top of the underlying Big Goose 

Member (fig. 5). The base of the Little Tongue Member 

appears to be older in the study area than it is throughout most of north-central Wyoming (see Sando, 1979, 

fig. 3).

ORIGIN

The lower part of the Little Tongue Member (lower 

solution zone) is interpreted as a leached evaporite, 

terrigenous, and carbonate sequence (Sando, 1974). 

Deposition was probably in shallow, highly saline lagoons.

The lithic facies of the upper limestone sequence in 

the member are suggestive of shallow-subtidal offshore 

marine environments. Both micrite and sparite are 

present, indicating periods of relatively quiet-water 

deposition interspersed with times of turbulent-water

deposition. The presence of shelly benthonic fossils 

throughout the limestone attests to predominantly normal marine conditions.

The Little Tongue Member is the most widespread of 

all the members of the Madison Limestone in Wyoming. It has been identified in all the places where 

Madison rocks are exposed throughout south-central, 

southeast, and north-central Wyoming and in extensions of the Wyoming Shelf into southern Montana. It 

may have completely covered the Laramie Range 

prong of the Transcontinental Arch prior to late uplift 

and erosion.

BULL RIDGE MEMBER

DESCRIPTION

The Bull Ridge Member is the youngest member of 

the Madison in the area studied. It conformably overlies the Little Tongue Member and is overlain unconformably by the Darwin Sandstone Member of the 

Casper Formation (pi. 1). The Bull Ridge Member is 

present only in the western part of the study area, 

where it was observed at Fremont Canyon and Casper 

Mountain. It was removed by post-Madison, pre-Casper 

erosion at Steeple Pasture and Box Elder Canyon. 

Where present, the Bull Ridge ranges from 5 ft (1.5 m) 

to 51.5 ft (15.8 m) thick.

The lower 3 to 39 ft (0.9-11.9 m) of the Bull Ridge 

Member in the study area consists predominantly of 

yellow- and red-weathering, platy, calcareous quartz 

siltstone or very fine-grained to fine-grained quartz 

sandstone that contains thin interbeds of brecciated 

fine-grained limestone and dolomite at some localities. 

Cherty, fine-grained dolomitic limestone breccia occurs 

at the base of the member in the Casper Mountain 

Road section. This unit is the upper solution zone of 

north-central Wyoming (Sando, 1974). Like the lower 

solution zone, this unit is thought to represent a 

leached evaporite-terrigenous-carbonate sequence.

The remaining upper part of the Bull Ridge Member 

consists mainly of gray-weathering fine-grained limestone in beds 0.1 to 1 ft (0.03 to 0.3 m) thick. At Casper 

Mountain, a thin unit of platy quartz siltstone and finegrained sandstone occurs near the top of the member, 

and the member is capped by a thin bed of irregularly 

laminated, probably stromatolitic limestone. The main 

part of the limestone is composed of micrite, pelmicrite, 

and biomicrite. At Fremont Canyon, post-Madison, 

pre-Casper erosion removed all of the limestone unit 

and left only 5 ft (1.5 m) of the upper solution zone at 

the top of the Madison beneath the Darwin Sandstone 

Member.
CASPER AND HARTVILLE FORMATIONS 15

FOSSILS, AGE, AND CORRELATION

No fossils were found in the upper solution zone. The 

limestone above the upper solution zone contains pelmatozoan debris, ostracodes, brachiopods, and corals. 

Syringopora sp., Vesiculophyllum sp., and Lophophyllum? sp. were identified in the unit at Casper Mountain.

In north-central Wyoming, the Bull Ridge Member 

contains a distinctive early Meramecian fauna that includes phaceloid lithostrotionoid corals, foraminifers of 

Mamet Zones 10-12, and conodonts of the texanus 

Zone. Although these critical fossils were not found in 

the study area, the corals that were found are similar 

to those associated with diagnostic fossils elsewhere. In 

the absence of contrary evidence, we assume that the 

Bull Ridge Member is the same age as it is in northcentral Wyoming.

ORIGIN

The rocks of the Bull Ridge Member record a depositional history similar to that of the underlying Little 

Tongue Member. Deposition of the Bull Ridge began 

with a period of restricted terrigenous-carbonateevaporite sedimentation in shallow lagoons followed by 

deposition of carbonates in freely circulating marine 

waters in offshore environments. The occurrence of 

probable stromatolites at the top of the member 

marked the return of intertidal-flat conditions similar 

to those represented in the Big Goose Member.

The former areal extent of the Bull Ridge Member is 

difficult to determine. Its present distribution is erratic 

throughout north-central and southern Wyoming, 

owing to the influence of post-Madison, pre-Amsden 

uplift and erosion. The discovery of remnants of the 

member in the northern Laramie Range was not expected because of its absence from the southern Wind 

River Mountains, Granite Mountains, western Owl 

Creek Mountains, and southern Bighorn Mountains 

(see Sando, Gordon, and Dutro, 1975, p. A17, pi. 2). 

Occurrences of the Bull Ridge in the study area suggests that the member formerly extended across the 

Laramie Range prong of the Transcontinental Arch. 

These occurrences also suggest that parts of the 

northern Laramie Range were sheltered from erosion 

prior to deposition of the Casper Formation.

POST-MADISON, PRE-CASPER SOLUTION 

FEATURES

Widespread solution features related to emergence 

and karst development prior to deposition of the Darwin Sandstone Member have been cataloged and described in the Madison Limestone throughout northcentral Wyoming (Sando, 1974; Sando, Gordon, and 

Dutro, 1975). These features include solution zones, 

sinkholes, joints, and caves in the Bull Ridge and Little 

Tongue Members. Henbest (1958) described and illustrated the unconformity and sinkholes at the top of the 

Madison on the west side of the North Platte River just 

northwest of our Hartville Canyon section. The occurrence in the solution cavities of sandstone continuous 

with the main body of the overlying Darwin Sandstone 

Member is important evidence for the postulated solution history and distinguishes these features from later 

superimposed solution features.

Definite sinkholes were not observed in the Madison 

of the Laramie Range, although a feature interpreted 

as a channel in the top of the Madison at Fremont 

Canyon may actually be a sinkhole (see description of 

Darwin Sandstone Member of Casper Formation). 

Sandstone-filled joints and other cavities are common 

features. Vertical and horizontal joints filled with 

sandstone were observed in the upper 12.5 to 15 ft (3.8- 

4.6 m) of the Bull Ridge Member at Casper Mountain 

and in the upper 16 ft (4.9 m) of the Little Tongue 

Member at Box Elder Canyon. Sandstone occurs as matrix in collapse breccia in the Little Tongue Member 60 

to 90.5 ft (18.3-27.6 m) below the top of the Madison at 

Fremont Canyon, 0 to 35 ft (0-10.7 m) below the top of 

the Madison at Steeple Pasture, and 16 to 57 ft (4.9- 

17.4 m) below the top of the Madison at Box Elder 

Canyon. At Box Elder Canyon, sandstone fills irregular cavities within the lower solution zone 57 to 85 ft 

(17.4-25.9 m) below the top of the Madison. These features indicate the same solution history for the 

Madison of the study area as previously described for 

the Madison of north-central Wyoming (Sando, 1974).

The youngest beds of the Madison in southeast Wyoming are probably of Late Mississippian (early Meramecian) age. The basal Darwin Sandstone Member of 

the Casper and Hartville Formations is of Pennsylvanian age. Therefore, uplift, erosion, and karst development began in the Meramecian and extended into 

Pennsylvanian time. Thus, the Madison Limestone in 

the study area was subjected to a longer period of emergency than it was in the Bighorn Mountains to the 

north, where transgression of the Darwin sea began in 

middle Chesterian time (Sando, Gordon, and Dutro, 

1975, p. A18).

CASPER AND HARTVILLE FORMATIONS

Interbedded quartz sandstone, limestone, and 

dolomitic limestone that unconformably overlie the
16 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

::^:^V^-BIJLJ::IIIPGE:;V^:^^::-

FIGURE 6. Interpretive field sketch of geologic relationships at contact between Madison Limestone and Casper Formation at Fremont Canyon section. Numbers refer to unit numbers in measured section description. SC, sandstone filling solution cavities.

Madison Limestone in the Laramie Range are referred 

to the Casper Formation (Darton, 1908), and correlative beds in the Hartville uplift are included in the 

Hartville Formation (Smith, 1903). Because the principal focus of this study was the pre-Pennsylvanian part 

of the Paleozoic sequence, only the lower parts of these 

formations were studied.

A persistent basal sandstone member of the Casper 

and Hartville in the study area is referred to the Darwin Sandstone Member (Blackwelder, 1918), which is 

extended into the study area from central Wyoming, 

where the Darwin is a member of the Amsden Formation (see Sando, Gordon, and Dutro, 1975). This usage 

of the Darwin differs significantly from that of Mallory 

(1967, 1975), who regarded the basal sandstone of the 

Casper Formation as a discrete unit separated geographically from the Darwin.

DARWIN SANDSTONE MEMBER

DESCRIPTION

The Darwin Sandstone Member is the oldest unit of 

the Casper and Hartville Formations in the study area. 

It overlies the Madison Limestone unconformably and 

is conformably overlain by undifferentiated interbedded sandstone and carbonate beds in the lower part of 

the Casper or Hartville (pi. 1). The thickness of the 

Darwin ranges from 6 ft (1.8 m) in the Casper Mountain TV Tower section to 60 ft (18.3 m) at Box Elder

Canyon. The member thickens both eastward and 

westward from Casper Mountain.

The contact between the Madison and the overlying 

Darwin Sandstone Member of the Casper and Hartville 

Formations in the study area is an irregular surface 

having a local relief of as much as 15 ft (4.6 m). An 

excellent exposure of the unconformity can be seen at 

Fremont Canyon, where the Darwin rests on a remnant 

of the upper solution zone of the Bull Ridge Member 

and on the upper part of the underlying Little Tongue 

Member (fig. 6). Maximum relief in the study area is 

estimated to be at least 52.5 ft (15.9 m), on the basis of 

preserved thickness of the Bull Ridge Member at 

Casper Mountain compared to the absence of this member at Steeple Pasture and Box Elder Canyon.

The Darwin Sandstone Member consists predominantly of fine-grained, calcareous, generally crossbedded quartz sandstone that weathers white, gray, yellow, orange, and red. The beds range from 0.3 to 4 ft 

(0.09-1.2 m) in thickness. Current ripples were observed at the top of the member at Box Elder Canyon.

Petrographic samples from the Darwin are exclusively quartzarenite as used by Pettijohn, Potter, and 

Siever (1972). Roundness of the quartz grains ranges 

from very angular to rounded. Sorting is fair at all 

localities except Box Elder Canyon, where the 

sandstone is well sorted. The most common accessory 

mineral is feldspar, which constitutes 1 percent or less 

of the rock at all localities. Tourmaline and zircon are
CASPER AND HARTVILLE FORMATIONS 17

present at Casper Mountain but account for less than 

1 percent of the rock. About 5 percent chert grains are 

present at Fremont Canyon. Heavy mineral residues 

are very low and consist of secondary hematite and 

limonite and rare magnetite. All samples are characterized by carbonate cement, predominantly calcite.

FOSSILS, AGE, AND CORRELATION

The lower 3.5 ft (1.1 m) of the Darwin in the Casper 

Mountain Road section contains molds and casts of 

large crinoid columnals and gastropods of indeterminate age. A well-rounded grain, barely recognizable as 

a fragment of the conodont Idiognathoides sp., was recovered from the upper 1 ft (0.3 m) of the Darwin, 7.9 

ft (2.4 m) above the base of the member, at the same 

locality (USGS 25904-PC) (pi. 1). Idiognathoides is indicative of a Pennsylvanian age.

Fossils have not been found in the Darwin in other 

areas where the unit has been studied. Sando, Gordon, 

and Dutro (1975, p. A23) regarded the Darwin as a 

time-trangressive facies that ranges in age from Meramecian to Chesterian in western and central Wyoming and into the Pennsylvanian in eastern Wyoming, 

based on the ages of fossils collected above and below 

the sandstone. The discovery of Pennsylvanian 

conodonts in the Darwin at Casper Mountain confirms 

the age predictable for the Darwin in this area using 

the transgressive facies model. The occurrence of 

Desmoinesian or younger fossils in the beds above the 

Darwin indicates a possible age range of Morrowan to 

Desmoinesian for the Darwin in this area.

ORIGIN

Sando, Gordon, and Dutro (1975, p. A23) postulated 

deposition of the Darwin Sandstone Member of the 

Amsden Formation in beaches and offshore bars adjacent to an eastward-transgressing shoreline following 

drowning of a fluvial system associated with postMadison karst development. The Darwin in the study 

area is regarded as an eastward extension of this transgressive nearshore facies.

POST-DARWIN BEDS

DESCRIPTION

Beds belonging to the Casper and Hartville Formations were examined only up to a stratigraphic level 

about 100 ft (30.5 m) above the base of the formation in 

the study area (pi. 1). These beds conformably overlie 

the Darwin Sandstone Member.

The post-Darwin beds consist of interbedded quartz 

sandstone, limestone, dolomite, and dolomitic limestone. Carbonate beds make up about 60 to 70 percent 

of the sequence. Limestone beds in the sequence are 

predominantly fine grained; dolomitic beds are 

medium crystalline. The limestone facies include 

micrite, biomicrite, pelmicrite, and rare pelsparite. 

Stromatolites are common. Beds are 2 ft (0.6 m) or less 

thick, and bedding is mostly irregular to nodular. The 

dolomitic beds are commonly sandy. Limestones 

weather mostly medium light gray, whereas dolomitic 

beds weather mostly yellowish gray.

The quartz sandstone is predominantly fine grained 

and in beds 0.1 to 2 ft (0.03-0.6 m) thick that weather 

white, gray, yellow, and red and are commonly crossbedded. Heavy minerals account for less than 1 percent 

of the rock and include secondary limonite and detrital 

tourmaline and magnetite.

FOSSILS, AGE, AND CORRELATION

Undetermined brachiopods, gastropods, ostracodes, 

and crinoidal debris are common constituents of the 

limestones. Foraminifers of Mamet Zone 25 or younger 

(Desmoinesian or younger) were found between about 

25 and 35 ft (7.6 and 10.7 m) above the base of the 

Casper Formation at Casper Mountain Road Section B 

and Steeple Pasture (pi. 1). Well-rounded grains barely 

recognizable as conodonts belonging to the genus Idiognathodus (Pennsylvanian) were found 25.9 (7.9 m) 

above the base of the Casper at Casper Mountain 

(pi. 1). A large, well-preserved conodont fauna (sample 

BAH-4, USGS 26026-PC), including Idiognathodus 

sinuosis and Hindeodus minutus, was found 16 ft 

(4.9 m) above the top of the Darwin Sandstone Member 

at Steeple Pasture. Thus, evidence from the present 

study suggests that the post-Darwin beds studied belong to the middle member of the Casper of Maughan 

(1979, p. U22, U23, fig. 10), who summarized fusulinid 

evidence for a Desmoinesian to Virgilian age for the 

member.

ORIGIN

The lithology and fauna of the carbonates is suggestive of offshore shallow-water marine bank deposition. 

Stromatolites in some beds may represent periods of 

intertidal or supratidal conditions. The quartz sandstones probably represent pulses of terrigenous sediment derived from upland areas on the Transcontinental Arch deposited in beaches and offshore bars.
18 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

R. 83 W. ^_________

.... , EXPLANATION

Tertiary sedimentary rocks

Casper Formation (part)

Qal.' . Quaternary alluvium

Bull Ridge and Little] Mississippjar

Tongue Members .... V Madison

,_ , Limestone Big Goose Member I

Mississippian and Devonian 

Englewood Formation and Devonian 

Fremont Canyon Sandstone

Precambrian granite

Contact

Strike and dip of bedding 

< « < < Stratigraphic section traverse

X Road cut where base of Fremont 

Canyon Sandstone is exposed

500

I

1000 1500 FEET

1 

100 200 300 400 METERS

FIGURE 7. Geologic sketch map of Fremont Canyon section. Base from Pathfinder Dam 7.5' minute quadrangle. Contour interval is 100 feet.

STRATIGRAPHIC SECTION DESCRIPTIONS

FREMONT CANYON SECTION

(Type section of Fremont Canyon Sandstone)

Section begins at foot of south-facing nose in NEV4 

sec. 21, T. 29 N., R. 83 W., Natrona County, at a point 

on the Fremont Canyon power plant road 2 mi (odometer) west of intersection with Kortes Road (fig. 7). This 

intersection is 6.2 mi south of Alcova on Wyoming 

Highway 220. The section is about 0.5 mi (odometer) 

east of the bridge over Fremont Canyon. The base of 

the Fremont Canyon Sandstone is exposed at several 

places along the foot of the hills here (fig. 8). The best 

exposure of this datum is in the road cut east of the 

section traverse (fig. 7). The section was measured with 

a Jacobs staff and steel tape.

Thickness

Casper Formation:

46. Dolobiomicrite; similar to unit 38; beds 

0.3 2 ft thick; undetermined brachiopods and gastropods from upper 

1.5 ft (USGS 26002-PC) -----------

45. Quartz sandstone; fine- to mediumgrained; weathers white; beds regular, 

0.2-1 ft thick ---------------------

44. Quartz sandstone; fine-grained; dolomitic; weathers grayish orange to 

moderate reddish orange; beds irregular, 0.1-0.2 ft thick ----------------

43. Dolomite; medium crystalline; irregularly laminated (stromatolitic?); 

weathers moderate reddish orange; 

single bed ------------------------

42. Quartz sandstone; fine-grained; friable; 

calcareous; weathers white; crossbedded (large scale), beds 0.5-2 ft thick;

Feet

7.0

14.0

2.8

1.0

Meters

2.1

4.3

0.9

0.3
STRATIGRAPHIC SECTION DESCRIPTIONS 19

FIGURE 8. Precambrian granite (pCg), Fremont Canyon Sandstone (Df), Englewood Formation 

(MDe), and Big Goose (Mmbg) and Little Tongue (Mmlt) Members of Madison Limestone in 

Fremont Canyon section.

Thickness 

Feet Meters

unit forms base of prominent white 

cliff. Barren conodont sample from 

lower foot (USGS 26001-PC) -------

41. Dolomite; medium crystalline; texture 

obscure; some beds slightly sandy; 

weathers grayish orange; beds 1-2 ft 

thick -----------------------------

40. Covered and dolomitic limestone float 

like unit 38; some beds in place in 

lower 4 ft -------------------------

39. Quartz sandstone; fine-grained; weathers grayish yellow; beds 0.1-0.3 ft 

thick; poorly exposed --------------

38. Dolopelmicrite; crinoidal; weathers 

grayish yellow to moderate orange 

pink; beds irregular, 0.5-2 ft thick; exposed in cliff. Barren conodont sample 

USGS 26000-PC 15 ft above base - -

37. Dolomitic limestone; like unit 35; poorly 

exposed ---------------------------

36. Micrite; recrystallized; like unit 34; 

poorly exposed --------------------

35. Dolomitic limestone; fine-grained; 

weathers yellowish gray; contains 

scattered crinoidal debris as molds 

and casts; beds 0.5-1 ft thick; poorly 

exposed ---------------------------

34. Micrite; recrystallized; with dolomitic 

partings; like unit 30; poorly exposed. 

Barren foram sample USGS 25999- 

PC 3 ft above base ----------------

33. Dolomite; sandy; like unit 31 ---------

10.0

10.0

10.0

2.0

28.0

3.0

2.0

3.0

6.5 

3.0

3.1

3.1 

3.1 

0.6

8.5 

0.9 

0.6

0.9

2.0 

0.9

Thickness

32. Quartz sandstone; fine-grained; weathers white to grayish yellow; crossbedded, beds 0.5 ft thick. Barren conodont 

sample USGS 25998-PC 2 ft above 

base. Traverse follows edge of cliff - -

31. Dolomite; fine to medium crystalline; 

sandy; some beds platy; beds 0.1-0.5 ft 

thick -----------------------------

30. Biomicrite, crinoidal, and pelsparite, 

stromatolitic; olive gray weathering 

medium light gray; irregular beds 

0.1-0.3 ft thick separated by orangeweathering dolomitic partings; grades 

into unit above. Indeterminate 

foraminifers from lower 0.5 ft (USGS 

25996-PC); barren foram sample 

USGS 25997-PC 1.5 ft above base --

Feet

3.0

2.5

Meters

0.9

0.8

3.5 1.1

Measured thickness of Casper Formation 

above Darwin Sandstone Member ------ 111.3 34.1

Darwin Sandstone Member: 

29: Quartz sandstone; fine-grained; weathers white, yellowish gray, grayish yellow, moderate orange pink, and moderate red; crossbedded, beds 4 ft thick; 

fills sinkholes in underlying units. 

Barren conodont samples 2 ft above 

base (USGS 25994-PC) and from 

upper foot (USGS 25995-PC) ------ 26.0 7.9

Total thickness of Darwin Sandstone Member ----------------------------------- 26.0 7.9
20 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness 

Feet Meters

Measured thickness of Casper Formation (incomplete)------------------------------------- 137.3 42.0

Madison Limestone:

Bull Ridge Member:

28. Quartz siltstone; platy; calcareous; 

weathers predominantly moderate red 

and grayish orange; a fine-grained 

dolomite bed about 0.2 ft thick in 

lower half and a fine-grained limestone bed 0.3 ft thick near middle; exposed on dipslope. Barren foram sample from limestone bed near middle 

(USGS 25993-PC). Unit represents 

lower solution zone ---------------- 5.0 1.5

Total thickness of Bull Ridge Member ---- 5.0 1.5

Little Tongue Member: 

27. Dolomite; predominantly fine-grained;

fossiliferous; weathers yellowish gray

to grayish yellow; beds undulant, 0.5-

1 ft thick; about 50 percent dark

brown chert in thick lenses and beds;

chert contains abundant brachiopods,

gastropods, and crinoid columnals;

unit exposed on dipslope. Undetermined brachiopods 3 ft below top

(USGS 25992-PC)----------------- 14.0 4.3

26. Pelmicrite, intramicrite, oosparite, and

oobiosparite; olive gray weathering

medium light gray to light gray; beds

regular but undulant, 0.5-2 ft thick;

about 10 percent brown chert nodules

and lenses; unit is main cliff-former.

Foraminifers of Mamet Zone 8 or 9,

4 ft above base (USGS 25989-PC) and

from upper foot (USGS 25991-PC);

barren foram sample 15 ft above base

(USGS 25990-PC) ----------------- 36.0 11.0

25. Biosparite, crinoidal; olive gray weathering medium light gray to light gray;

bedding undulant, 0.5-1 ft thick, brecciated in lower half, with sandstone

matrix; about 10 percent brown chert

nodules; unit is main cliff-former.

Abundant spiriferoid brachiopods

throughout (sample USGS 25988-PC

from? ft above base) ---- --- 10.5 3.2 

24. Limestone collapse breccia; mostly

crinoidal biomicrite in large angular

blocks up to several feet in diameter in

yellowish-weathering fine-grained

quartz sandstone matrix; limestone

weathers medium light gray to light

gray; about 10 percent brown chert

nodules; unit forms lower part of main

cliff. Spiriferoid brachiopods rare --- 20.0 6.1

23. Covered; float of silty fine-grained 

dolomite and chert breccia with matrix of silty dolomite weathering grayish yellow and siltstone weathering 

light red. Unit represents lower solution zone -------------------------

Thickness 

Feet Meters

13.0 4.0

Total thickness of Little Tongue Member - 93.5 28.6

Big Goose Member:

22. Micrite and dolomicrite; stromatolitic; 

abundant hemispherical stromatolites 

as much as 0.5 ft in diameter and 1 ft 

high, some silicified; beds 2 ft thick. 

USGS 25987-PC ------------------ 4.5 1.4

21. Dolomicrite; weathers yellowish gray; 

beds laminated, 0.2-0.5 ft thick; about 

20 percent brown chert lenses and 

stringers; partly brecciated, including 

large blocks at angles to bedding; contains at least two lenses of finegrained quartz sandstone as much as 

2 ft thick and 4 ft wide in solution cavities. Barren conodont sample USGS 

25986-PC 5 ft above base ---------- 19.0 5.8

20. Micrite and pelmicrite; olive gray 

weathering medium light gray; interbedded with fine-grained dolomitic 

limestone weathering yellowish gray; 

beds 0.5-1 ft thick; contacts fuzzy; all 

beds contorted, shattered, some brecciated; unit forms prominent cliff. 

Barren foram sample USGS 25985- 

PC 7 ft above base ---------------- 35.0 10.7

19. Covered and few outcrops of shattered 

fine-grained dolomitic limestone in 

lower half; float is dolomitic limestone 

and limestone from above ---------- 22.0 6.7

18. Dolomitic limestone; fine-grained; 

weathers yellowish gray; shattered 

and brecciated -------------------- 9.0 2.8

17. Covered and a few outcrops of finegrained dolomitic limestone at base; 

dolomitic limestone float ----------- 6.0 1.8

16. Dolomitic limestone and dolomite; 

medium crystalline; weathers yellowish gray; crossbedded, beds 0.3 0.5 ft 

thick; forms cliff in ridge. Barren 

conodont sample USGS 25984-PC 

from upper foot ------------------- 4.0 1.2

15. Dolomitic pelmicrite; weathers yellowish gray; beds regular to irregular, 

0.3-0.5 ft thick; some beds faintly 

laminated; some beds shattered; structure obscure in most beds; about 5 percent brown chert nodules and 

stringers; unit forms ridge. Barren 

conodont sample USGS 25983-PC 8 ft 

above base ------------------------ 11.5 3.5
STRATIGRAPHIC SECTION DESCRIPTIONS 21

Thickness 

Feet Meters

14. Dolomicrite and crinoidal dolomite; 

weathers yellowish gray; crossbedded, 

beds 0.3-1 ft thick; forms prominent 

cliff. Abundant brachiopods as molds 

and casts in lower half. Brachiopods 

3-6 ft above base (USGS 25981-PC); 

barren conodont sample USGS 25982- 

PC from upper foot ---------------- 14.5

13. Covered and dolomitic limestone

float ------------------------------ 7.5

12. Dolomicrite; laminated (stromatolitic); 

weathers yellowish gray; beds irregular, 0.5-1 ft thick. Barren conodont 

sample USGS 25980-PC from lower 

foot ------------------------------ 4.5

11. Dolomicrite; crinoidal, silty; weathers 

yellowish gray; bed regular, 0.1-0.5 ft 

thick; some beds faintly laminated; 

chert nodules in upper 2 ft; poorly exposed. Barren conodont sample USGS 

25979-PC from lower foot --------- 11.0

10. Dolomicrite; olive gray weathering yellowish gray to grayish orange; beds irregular to nodular, 0.1-0.5 ft thick; 

about 40 percent milky white and gray 

irregular nodular chert. Barren 

conodont samples USGS 25978-PC 

7 ft above base and USGS 25977-PC a 

foot above base -------------------- 12.5 3.8

4.4

2.3

1.4

3.4

Total thickness of Big Goose Member ----- 161 

Total thickness of Madison Limestone -------- 259.5

49.2

79.3

Englewood Formation:

9. Dolomicrite; silty and sandy; fine quartz 

sand in lower foot grades up into silty 

beds; weathers yellowish gray; beds 

regular, 0.2-0.3 ft thick. Polygnathus 

inornatus rostratus and P. longiposticus from lower foot (USGS 25976-PC). 

Disconformity at base of unit marks 

base of Mississippian --------------

8. Quartz sandstone; like unit 6 but not 

conglomeratic ---------------------

7. Covered; probably siltstone, like unit 

5 .................................

6. Quartz sandstone; predominantly fineto medium-grained with conglomeratic layers; friable to quartzitic; 

weathers white, brown, and pink; beds 

regular, 0.3-1 ft thick. Polygnathus 

semicostatus, Clydagnathus ormistoni, and Scaphignathus sp. from 

lower foot (USGS 25975-PC) -------

5. Covered and outcrop of platy calcareous 

quartz siltstone weathering moderate 

red at base; unit is probably all siltstone -----------------------------

4.0

1.0

2.0

1.2 

0.3 

0.6

4.0

6.0

Total thickness of Englewood Formation ------ 17.0

1.2

1.8 

5.1

Thickness 

Feet Meters

Fremont Canyon Sandstone:

4. Quartz sandstone; predominantly

medium- to coarse-grained; with scattered layers of very coarse sand and

rare pebbles; friable to quartzitic;

weathers light gray, brown, red, and

orange; crossbedded, beds 0.1-0.3

thick; unit forms cliffy slope. Barren

conodont samples from lower foot, and

5,12,16, 20, 25, 30, 35, 40, 45, 50, 55,

60, 65, 70, 75, 80, 85, 90, 95, 99, 110,

115, 121, 125,130,140,147,150,155,

160, and 165 ft above base (USGS

25943 25974-PC) ---------------- 166.5

3. Quartz sandstone; conglomeratic;

medium- to very coarse sand with layers of quartz and feldspar pebbles as

much as 10 mm in diameter; weathers

white, brown, and red; crossbedded,

beds 0.3-1.5 ft thick. Barren conodont

samples from lower foot and 5,10, and

15 ft above base (USGS 25939 

25942-PC)------------------------

2. Conglomerate; quartz pebbles up to

0.2 ft in diameter, rounded to angular,

in matrix of medium to coarse quartz

and feldspar sand. Altitude 5,800 ft at

base. Barren conodont sample USGS

25938-PC from lower foot ----------

50.8

17.5 5.3

2.0 0.6

Total thickness of Fremont Canyon Sandstone - 186.0 56.7

Precambrian granite:

I. Granite; equigranular; pink; exposed in 

draw east of main traverse line; 0.1 ft of 

relief at top.

CASPER MOUNTAIN ROAD SECTION A

Section begins in road cut on east side of Casper 

Mountain Road at a point about 40 yd north of intersection with dirt road leading to cabins on west side of road 

in NEV4SEV4 sec. 8, T. 32 N., R. 79 W., Natrona County 

(fig. 9). The road cut is covered by slump above the top 

of unit 5 so that the top of the Fremont Canyon Sandstone cannot be determined with confidence in this section. A conodont sample from the lower foot of unit 4 

(USGS 25801-PC) and 28 conodont samples collected 

at 2-ft intervals from unit 5 (USGS 25802 25829-PC) 

were barren. These samples were also used for petrographic analysis. Section was measured with a steel 

tape.
22 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

R. 79 W. ___________

EXPLANATION

Pennsylvanian

Casper Formation (part)

Bull Ridge and Little 1 Mississippian 

Tongue Members I> Madison

Limestone 

Big Goose Member J

Mississippian and Devonian 

Englewood Formation and Devonian 

Fremont Canyon Sandstone

Precambrian granite

Contact 

 High-angle transverse fault

Strike and dip of bedding 

< < < < < Stratigraphic section traverse

Landslide (Mmbl)

500 1000 1500 FEET

100 200 300

I 

400 METERS

FIGURE 9. Geologic sketch map of Casper Mountain Road (1) and TV Tower (2) sections. Base from Casper 7.5' quadrangle. Contour interval is 100 feet.
STRATIGRAPHIC SECTION DESCRIPTIONS 23

FIGURE 10. Fremont Canyon Sandstone (Df); Englewood Formation (MDe); Big Goose (Mmbg), 

Little Tongue (Mmlt), and Bull Ridge (Mmbr) Members of Madison Limestone; and Casper 

Formation (IPc) exposed in cliffs at front of Casper Mountain northeast of Casper Mountain 

Road section.

Thickness

Fremont Canyon Sandstone:

5. Quartz sandstone; friable to quartzitic, 

predominantly medium- to coarsegrained, with abundant thin layers of 

very coarse sand; grains mostly 

rounded; weathers predominantly yellowish gray to grayish orange with 

minor pink and red stain; beds 0.1-0.4 

ft thick parting into units as much as 

3 ft thick; intricately crossbedded; current ripples, sets 0.1-0.4 ft thick, dipping north at about 30° to bedding; a 

few thin, greenish, discontinuous 

shaly zones in upper half; linear ichnofossils parallel to bedding seen on a 

few float blocks -------------------

4. Quartz sandstone; like unit above but 

poorly exposed and deeply weathered; 

outcrop brownish; exposed by trenching -------------------------------

3. Covered and loose blocks of quartz sandstone like unit above; blocks of sandstone in correct bedding orientation at 

base; yellowish and tan soil zone

Total thickness of Fremont Canyon Sandstone 

(incomplete) ------------------------------

Feet Meters

56.0

9.0

5.0

17.1

2.8

1.5

70.0

Precambrian granite:

2. Covered and loose blocks of granite and

minor sandstone; red soil zone ------ 21.4

1. Granite; composed of pink feldspar, biotite, and quartz in equal grains 2-5 mm

21.4

6.5

Thickness 

Feet Meters

in diameter; weathers pink; poorly foliated; massive ----------------------- Not measured

CASPER MOUNTAIN ROAD SECTION B

Section begins in road cut 180 yd northwest of section 

A at a point directly opposite macadam road leading to 

cabins on west side of road (fig. 9); granite is exposed 

just below road on west side where an old foundation 

rests on granite. Section proceeds northwestward in 

road cuts to base of unit 28, where traverse continues 

up cliff face south of main bend in road. The Paleozoic 

section forms bold cliffs at the front of Casper Mountain 

(fig. 10).

Thickness

Casper Formation:

60. Sandy dolomitic limestone and dolomitic 

sandstone; like unit 58 ------------

59. Quartz sandstone; friable; calcareous; 

predominantly fine-grained; weathers 

white to yellowish gray; beds 0.1- 

0.3 ft thick; a few beds have smallscale crossbedding. Barren conodont 

samples from lower foot (USGS

25911-PC) and upper foot (USGS

25912-PC) ------------------------

Feet

3.5

Meters

1.1

16.0 4.9
24 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness

58. Dolomitic limestone, sandy, and dolomitic quartz sandstone; predominantly fine-grained; weathers yellowish gray; bedding irregular, beds 

0.5-2 ft thick; calcite vugs; forms 

bench ----------------------------

57. Fossiliferous micrite and biomicrite, 

partly recrystallized; olive gray 

weathering medium light gray, 

stained moderate red in lower part; 

beds nodular to stylolitic, 0.1-0.3 ft 

thick, becoming thicker in upper half, 

many with red silty partings; forms 

cliff. Indeterminate foraminifers, gastropods, pectinoid clams, and brachiopods in sample 1 ft above base 

(USGS 25909-PC); barren foram sample (USGS 25910-PC) 10 ft above 

base ------------------------------

56. Quartz sandstone; predominantly finegrained; weathers pale yellowish 

orange; beds 0.3 ft thick; poorly exposed on bench. Well-rounded grains 

of Idiognathodus sp. (USGS 25908- 

PC)-------------------------------

55. Biomicrite and fossiliferous pelmicrite; 

contains abundant dolomite rhombs in 

upper half; olive gray weathering 

medium light gray. Indeterminate 

brachiopods and ostracodes in lower 

2 ft (USGS 25906-PC); gastropods 

and foraminifers of Mamet Zone 25 or 

younger in upper foot (USGS 25907- 

PC) ------------------------------

54. Micrite and fossiliferous pelmicrite; 

olive gray weathering medium light 

gray to light gray; beds regular, stylolitic, 0.1-0.4 ft thick; vertical joints 

filled with yellow-weathering calcareous siltstone. Indeterminate brachiopods and ostracodes in lower foot 

(USGS 25905-PC) -----------------

Measured thickness of Casper Formation 

above Darwin Sandstone Member ------

Darwin Sandstone Member:

53. Quartz sandstone; predominantly finegrained; friable; calcareous; weathers 

yellowish gray to pale yellowish 

orange; faintly crossbedded, beds 0.5 

2 ft thick. Idiognathoides sp. (one specimen well-rounded) in upper foot 

(USGS 25904-PC) -----------------

52. Quartz sandstone; dolomitic; predominantly fine-grained; weathers yellowish gray to grayish yellow; poorly bedded; contains molds and casts of large 

crinoid columnals and gastropods.

Feet Meters

7.5 2.3

15.5

0.6

4.7

0.2

13.0 4.0

4.0 1.2

60.1 18.4

5.4 1.7

Thickness 

Feet Meters

Barren conodont sample from lower

foot (USGS 25903-PC) ------------ 3.5 1.1

2.8

1.5

1.0

0.5

0.3

4.5 1.4

Total thickness of Darwin Sandstone Member ----------------------------------- 8.9

Measured thickness of Casper Formation (incomplete)------------------------------------- 69.0 21.2

Madison Limestone:

Bull Ridge Member:

51. Pelmicrite; silty; stromatolitic; partly 

recrystallized; having irregular fine 

lamination; olive gray weathering 

medium light gray. Barren foram 

sample 0.5 ft above base (USGS 

25902-PC) ------------------------

50. Quartz siltstone and fine-grained sandstone; weathers dark reddish brown to 

grayish yellow; contains many calcite 

vugs ------------------------------

49. Fossiliferous micrite and pelmicrite; 

olive gray weathering medium light 

gray; beds 0.1-0.2 ft thick, separated 

by 2-3-mm-thick silty yellowishweathering partings; quartz sandstone in vertical joints. Indeterminate 

crinoid debris in lower foot (USGS 

25900 PC); indeterminate ostracodes 

in upper foot (USGS 25901-PC) ----

48. Biomicrite; olive gray weathering 

medium light gray to light gray; beds 

0.5 1 ft thick; contains a lens of finegrained quartz sandstone in a solution 

cavity parallel to bedding and sandstone in horizontal and vertical joints 

that lead to top of unit 51. Crinoidal 

debris, spiriferoid brachiopods, gastropods, bryozoans, and Syringopora; 

Vesiculophyllum? sp. from 3 4.5 ft 

above base (USGS 25899-PC) ------

47. Covered and rubble from beds above, 

mostly limestone and sandstone. Indeterminate brachiopods in loose limestone block probably from Casper Formation 3 ft above base (USGS 

25898-PC) ------------------------

46. Covered and float of platy calcareous 

siltstone weathering grayish yellow; 

break in slope at top. Top marks probable top of upper solution zone -----

45. Dolomitic limestone breccia; cherty; 

clasts fine grained, olive gray weathering yellowish gray, some laminated, 

angular to rounded, mostly 0.1 ft or 

less in diameter; matrix fine-grained 

dolomitic limestone; about 20 percent 

fragmented gray, brown, and white 

chert; beds irregular, 0.3-0.5 ft thick; 

unit poorly exposed on slope above 

cliff ------------------------------

5.5 1.7

14.0

5.0

4.3

1.5

20.0 6.1

Total thickness of Bull Ridge Member ---- 51.5 15.8
STRATIGRAPHIC SECTION DESCRIPTIONS 25

Thickness 

Feet Meters

Little Tongue Member:

44. Micrite and crinoidal pelmicrite, partly 

recrystallized and partly dolomitized; 

olive gray weathering medium light 

gray; beds regular, 0.5-1 ft thick, bedding generally obscure; about 20 percent brown chert lenses and stringers 

parallel to bedding; unit forms massive cliff. Spiriferoid brachiopods from 

19 ft above base (USGS 25895-PC); 

barren foram samples from lower foot 

(USGS 25893-PC), 10 ft above base 

(USGS 25894-PC), 34 ft above base 

(USGS 25896-PC), and 47 ft above 

base (USGS 25897-PC). Traverse offset 

about 100 yd updip along top of cliff at 

top of unit ------------------------ 47.0 14.3

43. Limestone collapse breccia; clasts are 

olive-gray micrite weathering 

medium light gray; angular fragments up to 0.5 ft in diameter in calcareous rock flour matrix; exposed in a 

few outcrops in slope -------------- 18.0 5.5

42. Covered and unreliable blocks of limestone collapse breccia like that in unit 

above ----------------------------- 15.0 4.6

41. Covered and unreliable blocks of 

dolomite and chert breccia; angular 

fragments of fine-grained dolomite 

and chert like that in units below as 

much as 0.3 ft in diameter in finegrained dolomite matrix. Unit represents lower solution zone ---------- 13.0 4.0

Total thickness of Little Tongue Member - 93.0 28.4

Big Goose Member:

40. Dolomitic limestone; fine-grained; 

weathers yellowish gray; shattered; 

beds regular, 0.3-0.5 ft thick; exposed 

at top of cliff in road cut ----------- 10.0 3.1

39. Micrite and pelmicrite; partly recrystallized; olive gray weathering light 

gray; beds regular, 0.5-3 ft thick, 

massive in appearance; 5 percent or 

less black chert nodules. Barren foram 

samples 5 ft and 10 ft above base 

(USGS 25891,25892-PC) ---------- 16.0 4.9

38. Dolomite and dolomitic limestone, like

unit 36; contacts irregular --------- 8.0 2.4

37. Pelmicrite; algal (cysts); partly recrystallized; olive gray weathering 

medium light gray to light gray; beds 

regular, 0.3-1 ft thick, massive in appearance. Barren foram and conodont 

samples a foot above base (USGS 

25889-PC) and from upper foot 

(USGS 25890-PC). Traverse ascends 

notch in cliff here ----------------- 6.5 2.0

Thickness

Feet Meters

36. Dolomicrite, fractured, recrystallized, 

like unit 35, and limestone, finegrained, olive gray weathering light 

gray; lenses with fuzzy boundaries, 

beds 0.5-2 ft thick; entire unit shattered and composed of breccia and 

pseudobreccia. Barren foram sample a 

foot above base (USGS 25888-PC) - - 

35. Dolomicrite; fractured; medium light 

gray weathering yellowish gray to 

grayish orange; beds irregular, 0.3- 

2 ft thick; shaly partings weather pale 

red to dark yellowish orange; entire 

unit shattered and composed of breccia and pseudobreccia. Barren conodont sample 2 ft below top (USGS 

25887-PC) ------------------------

34. Dolomicrite; like unit 33; badly shattered; bedding obscure--------------

33. Dolomicrite and scattered vuggy layers 

of dolomitized crinoidal biomicrite; 

medium gray weathering yellowish 

gray; beds regular, 0.3-2 ft thick; 

about 20 percent gray, brown, and 

white chert in thin stringers and 

minor small nodules; entire unit is 

well bedded but shattered; no breccia 

seen; many small faults ------------

Conodont samples: 

USGS 25886-PC, 35 ft above basebarren

25885-PC, 30 ft above basebarren 

25884-PC, 25 ft above base 

Polygnathus sp. 

25883-PC, 20 ft above base 

Patrognathus andersoni 

25882-PC, 15 ft above base 

Patrognathus andersoni, 

Bispathodus aculeatus 

25881-PC, 10 ft above basebarren

25880-PC, 5 ft above base 

Pandorinellina n. sp. (Pa 

element)

14.5 4.4

5.0

14.0

1.5

4.3

36.5 11.1

Total thickness of Big Goose Member ----- 110.5 

Total thickness of Madison Limestone -------- 255.0

33.7

77.9

Englewood Formation:

32. Dolobiomicrite; crinoidal, weathers yellowish gray to dark yellowish orange; 

beds 0.5 ft thick; very vuggy. Polygnathus inornatus and Patrognathus 

andersoni in lower foot (USGS 25879- 

PC) ------------------------------

31. Quartz siltstone; weathers dark yellowish orange to moderate brown; beds 

0.1-0.5 ft thick; a few shaly partings. 

Polygnathus inornatus a foot above

3.0 0.9
26 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness 

Feet Meters

base (USGS 25878-PC). Disconformity at base of unit marks base of Mississippian -------------------------

30. Quartz sandstone; predominantly very 

fine- to medium-grained, with some 

layers up to very coarse-grained; 

weathers white to grayish red; crossbedded, beds 0.3-1 ft thick; a few interbeds of greenish-weathering silty 

clay shale as much as 0.3 ft thick. Barren conodont samples 4 ft above base 

(USGS 25876-PC) and from upper 

foot (USGS 25877-PC) ------------

29. Quartz siltstone and silty dolomicrite 

with some thin layers of fine quartz 

sand; weathers dark yellowish orange 

to very dusky red; beds 0.1-0.5 ft 

thick, separated by beds of silty clay 

shale weathering grayish green 0.1- 

0.3 ft thick; some beds appear to have 

dessication cracks; salt casts in float; 

unit stands in marked contrast to gray 

sandstone below. Barren conodont 

samples from lower 0.3 ft (USGS

25872-PC), 3 ft above base (USGS

25873-PC), 6 ft above base (USGS

25874-PC), and 6.3 ft above base 

(USGS 25875-PC) -----------------

1.5 0.5

10.5 3.2

7.0 2.1

Total thickness of Englewood Formation ------ 22.0 6.7

Fremont Canyon Sandstone:

28. Quartz sandstone; friable; predominantly medium- to coarse-grained; 

crossbedded (current ripples), beds 

0.1-0.5 ft thick; weathers like unit 27; 

pink- and orange-weathering layers of 

silt and fine sand 0.1 ft thick or less; 

beds tend to break out thicker than in 

unit below. Barren conodont samples 

5 ft above base (USGS 25869-PC), 5 ft 

below top (USGS 25970-PC), and 

from upper 0.5 ft (USGS 25871-PC). 

Measured up cliff face just south of 

bend in road ----------------------

27. Quartz sandstone; medium- to very 

coarse-grained; crossbedded (current 

ripples), beds 0.1-0.5 ft thick; weathers white, gray, tan, orange with some 

pink stain; mostly friable, some 

quartzitic; abundant interbeds of silty, 

sandy clay shale weathering mostly 

dusky yellow green; some orange and 

red beds; shaly beds 0.1-0.3 ft thick, 

containing abundant linear ichnofossils mostly parallel to bedding; unit 

exposed at turn in road. Barren 

conodont samples from lower 0.1 ft 

(USGS 25861-PC), 5.2 ft above base

35.0 10.7

Thickness 

Feet Me,

(USGS 25862-PC), 16.4 ft above base 

(USGS 25863-PC), 18.7 ft above base 

(USGS 25865-PC), and from upper 

0.3 ft (USGS 25868-PC); trails from 

16.4 ft above base (USGS 25864-PC) 

and 20.5 ft above base (USGS 25867- 

PC) ------------------------------

26. Quartz sandstone; predominantly 

medium- to coarse-grained with abundant layers of very coarse sand; predominantly friable, with few 

quartzitic beds; weathers white, tan, 

and orange, with minor pink stain; intricately crossbedded (current ripples), beds 0.1-0.5 ft thick; measured 

along road cut. Barren conodont samples 5,10,15, 20, 25, 30, 35, 40, and 45 

ft above base (USGS 25852 25860- 

PC); paleomagnetism samples 

15.3, 22.4, and 22.8 ft above base 

(ML1-3) --------------------------

25. Quartz sandstone; friable, white, crossbedded; thin green clay parting at 

top -------------------------------

24. Clay shale and clay, micaceous, like unit 

20. Barren conodont sample (USGS 

25851-PC) ------------------------

23. Quartz sandstone, like unit 19 -------

22. Clay, like unit 16. Barren conodont sample (USGS 25850-PC) -------------

21. Quartz sandstone, like unit 19 -------

20. Clay shale and clay; silty and sandy; micaceous; weathers dusky yellow green. 

Barren conodont sample USGS 

25849-PC ------------------------

19. Quartz sandstone; predominantly 

coarse- to very coarse-grained, with 

some pebble layers; crossbedded, beds 

0.2-1 ft thick; weathers yellowish 

gray and pale orange; resistant beds at 

top of road cut; unit measured by projection across covered interval. Barren 

conodont samples from lower 0.5 ft 

(USGS 25847-PC) and 5 ft above base 

(USGS 25848-PC) -----------------

18. Clay, silty, like unit 16. Barren conodont 

sample USGS 25845-PC -----------

17. Quartz sandstone; like unit 13; green 

clay bed 0.1 ft thick 1 ft above base and 

0.3 ft below top; very deeply weathered. Barren conodont sample from 

lower foot (USGS 25844-PC) -------

16. Clay, silty, like unit 14; weathers dusky 

yellow green. Barren conodont sample 

USGS25843-PC ------------------

15. Quartz sandstone, like unit 13, very 

deeply weathered. Barren conodont 

sample USGS 25842-PC -----------

14. Clay; silty; weathers very dusky red and 

dusky yellow green. Barren conodont 

sample USGS 25841-PC -----------

22.3

47.5 14.5

0.4

0.3 

0.2

0.2 

0.9

0.2

0.1

0.1 

0.1

0.1 

0.3

0.1

8.5 2.6 

0.4 0.1

3.0

0.3

1.0

0.3

0.9

0.1

0.3

0.1
STRATIGRAPHIC SECTION DESCRIPTIONS 27

Thickness 

Feet Meters

13. Quartz sandstone; predominantly 

medium- to coarse-grained, with some 

very coarse sand and pebbles; weathers yellowish gray and orange; no 

crossbedding seen; very deeply weathered. Barren conodont sample from 

lower half (USGS 25840-PC) ------

12. Quartz siltstone, clayey, micaceous; 

weathers very dusky red; shaly. 

Barren conodont sample USGS 

25839-PC ---------.-----------..-

11. Quartz sandstone; predominantly 

coarse- to very coarse-grained; like 

unit 5; weathers tan and orange like 

beds below; crossbedded, beds 0.2 0.3 

ft thick; some resistant beds; a few 

thin conglomerate layers. Barren 

conodont sample from lower foot 

(USGS 25838-PC) -----------------

10. Quartz conglomerate, sandy, like unit 6 

but contains more sand (about 5 percent); contains abundant black pebbles; resistant bed that can be traced 

about 50 yd laterally. Barren conodont 

sample from lower foot (USGS 25837- 

PC) ------------------------------

9. Quartz sandstone; like unit 5; deeply 

weathered in road cut; resistant near 

middle. Barren conodont sample from 

lower foot (USGS 25836-PC) -------

8. Quartz conglomerate; sandy; like unit 6; 

deeply weathered in road cut. Barren 

conodont sample from lower foot 

(USGS 25835-PC) -----------------

7. Quartz sandstone; like unit 5 but a little 

more conglomeratic; deeply weathered 

in road cut. Barren conodont sample 

from lower foot (USGS 25834-PC) --

6. Quartz conglomerate; sandy; like unit 4; 

pebbles as much as 30 mm in diameter; deeply weathered in road cut. Barren conodont sample from lower foot 

(USGS 25833-PC) -----------------

5. Quartz sandstone; predominantly 

coarse- to very coarse-grained with 

some pebbles up to 5 mm in diameter; 

clasts subangular to rounded; crossbedded, beds 0.1-0.3 ft thick; weathers tan; deeply weathered in road cut. 

Barren conodont sample from lower 

foot (USGS 25832-PC) ------------

4. Quartz conglomerate; sandy; pebbles as 

much as 20 mm in diameter, subangular to rounded; poorly bedded; contains a few granite pebbles; deeply 

weathered to red micaceous clay; exposed by trenching. Barren conodont 

samples from lower foot (USGS

25830-PC) and upper foot (USGS

25831-PC)------------------------

1.2 0.4

0.2 0.1

3.0 0.9

0.7

1.6

2.0

1.7

2.0

0.2

0.5

0.6

0.5

0.6

1.4 0.4

2.2-3 0.6-0.9

Total thickness of Fremont Canyon Sandstone - 137.3 42.0

Thickness 

Feet Meters

Precambrian granite:

3. Clay; micaceous; red; represents weathered granite in place; 0.8 ft of relief at 

top; exposed in trench on east side of 

road ------------------------------ 1.0

2. Covered slope to edge of road --------- 5.0

1. Granite; pink; like unit 1 of section A;

massive rounded outcrops ---------- 10+

0.3 

1.5

3.1

CASPER MOUNTAIN TV TOWER SECTION

Section begins at top of granite exposure in saddle 

about 20 ft east of dirt road to TV tower at a point 

directly under power line (fig. 9). Initial leg of traverse 

follows power line up sandstone cliff. Section was measured mostly with a Jacobs staff. The Paleozoic section 

is well displayed in cliffs just east of the section traverse (fig. 11).

Thickness 

Feet Meters

Casper Formation:

20. Pelmicrite and pelsparite; fossiliferous; 

partly fractured; beds regular, 0.1-0.3 

ft thick. Orthotetoid brachiopods from 

throughout unit (USGS 25937-PC); 

barren foram samples from lower foot 

(USGS 25935-PC) and upper foot 

(USGS 25936-PC). Section terminates at top of cliff ----------------

Darwin Sandstone Member:

19. Quartz sandstone; fine-grained; calcareous; weathers yellowish gray and 

grayish orange; some beds crossbedded, beds 0.3-0.5 ft thick. Barren 

conodont sample 3 ft above base 

(USGS 25934-PC) -----------------

Total thickness of Darwin Sandstone 

Member ------------------------------

Measured thickness of Casper Formation 

(incomplete) ------------------------------

7.0 2.1

6.0 1.8

6.0 

13.0

1.8 

3.9

Madison Limestone:

Bull Ridge Member:

18. Micrite; irregularly laminated, probably 

stromatolitic; olive gray weathering 

medium light gray ----------------

17. Quartz siltstone and fine-grained sandstone; weathers grayish orange; platy; 

very calcareous; contacts irregular but 

seemingly gradational. Barren conodont sample (USGS 25933-PC) -----

0.7

14

0.2

0.4
28 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness

Feet Meters

16. Micrite; fossiliferous (ostracodes); olive 

gray weathering medium light gray; 

nodular bedded, beds 0.1-0.3 ft thick; 

yellowish-weathering silty partings. 

Barren foram sample from upper foot 

(USGS 25932-PC) -----------------

15. Micrite and pelmicrite; crinoidal; olive 

gray weathering light gray to medium 

light gray; beds 0.5-1 ft thick, indistinct; vertical and horizontal joints 

filled with yellow- and brownweathering quartz sandstone; about 

10 percent incipient brown chert 

lenses. Syringopora, horn corals, large 

orthotetoid brachiopods, and bryozoans throughout; Lophophyllum? sp. 

and Vesiculophyllum sp. from 5 to 10 

ft above base (USGS 25931-PC) ----

6.0 1.8

10.0 3.1

FIGURE 11. Fremont Canyon Sandstone (Df); Englewood Formation 

(MDe); Big Goose (Mmbg), Little Tongue (Mmlt), and Bull Ridge 

(Mmbr) Members of Madison Limestone; and 'Casper Formation 

( PC) exposed in west wall of canyon east of Casper Mountain TV 

Tower section.

Thickness 

Feet Meters

14. Quartz sandstone; fine- to very finegrained; very calcareous; friable to 

hard; weathers yellowish gray to grayish orange; beds irregular, 0.1-0.3 ft 

thick; upper half of unit poorly exposed. Unit represents upper solution 

zone ------------------------------

Total thickness of Little Tongue Member - 

Big Goose Member:

9. Micrite, fractured and laminated, and 

rare intra-biosparite; olive gray 

weathering medium light gray to light 

gray; beds regular, 0.5-2 ft thick; 

about 10 percent chert lenses in upper 

half; unit forms cliff and was measured along rim of canyon. Barren 

foram samples a foot above base 

(USGS 25924-PC) and 10 ft above 

base (USGS 25925-PC); foraminifers 

of Mamet Zone 8 (upper) from a foot 

below top (USGS 25926-PC) -------

3.0 0.9

3.0

Total thickness of Bull Ridge Member - - - - 21.1

Little Tongue Member:

13. Micrite and dismicrite; fossiliferous; 

olive gray weathering medium light 

gray; some beds nodular; beds 0.1 0.3 

ft thick; about 20 percent incipient 

brown chert. Indeterminate brachiopods from upper foot (USGS 

25930-PC)------------------------

12. Biomicrite, pelmicrite, oomicrite, and 

biosparite; crinoidal; olive gray 

weathering medium light gray to light 

gray; beds undulant, 0.5 1 ft thick; 

about 10 percent brown chert lenses 

and nodules; collapse breccia in lower 

15 ft. Spiriferoid brachiopods throughout; Vesiculophyllum sp. 30 ft above 

base (USGS 25929-PC); brachiopods 

from 2 ft above base (USGS 25928- 

PC) ---------.--..----------------

11. Covered and float of breccia like that below; yellowish-weathering platy calcareous siltstone. Top of lower solution zone at top of unit ------------

10. Breccia; clasts predominantly micrite 

(olive gray weathering medium light 

gray), brown chert (5 percent), and 

fine-grained dolomitic limestone 

weathering yellowish gray to grayish 

yellow (10 percent); matrix calcareous, fine-grained, weathering 

very light gray; clasts angular, mostly 

0.1 ft or less in diameter, but blocks as 

much as 1 ft in diameter are also 

present; bedding obscure (fig. 12). 

Base of lower solution zone at base of 

unit. Lithic sample (USGS 25927-PC) 

near middle -----------------------

6.4

0.9

32.0

5.0

9.8

1.5

10.0 3.1

50.0 15.3

21.0 6.4
STRATIGRAPHIC SECTION DESCRIPTIONS 29

Thickness 

Feet Meters

8. Covered and large blocks of limestone 

from unit above; no dolomite seen; 

forms slope leading up to cliff ------ 13.0 4.0

7. Dolomite, like unit 6, and oomicrite, 

olive gray, interbedded; beds 0.3-1 ft 

thick; fuzzy boundaries; poorly exposed on slope. Indeterminate 

foraminifers from lower foot (USGS 

25922-PC); barren foram sample 5 ft 

above base (USGS 25923-PC) ------ 15.0 4.6

6. Dolomite; fine-grained; weathers yellowish gray; faintly laminated; beds 

0.3-0.5 ft thick; about 20 percent 

brown, gray, and white chert in irregular patches and stringers; unit about 

90 percent covered on slope; best exposures are at canyon rim east of traverse. Barren conodont sample 7 ft 

above base (USGS 25921-PC) ------ 38.0 11.6

Total thickness of Big Goose Member 

Total thickness of Madison Limestone -------

Englewood Formation:

5. Covered; dark-brown soil contains pieces 

of dark-reddish-brown quartz siltstone 

and sandstone ---------------------

87.0

158.1

17.0

26.6

48.3

5.2

Total thickness of Englewood Formation ------ 17.0

Fremont Canyon Sandstone:

4. Quartz sandstone; predominantly 

medium- to coarse-grained with scattered layers of very coarse sand; friable to hard; weathers white, yellowish gray, grayish yellow, and grayish

5.2

FIGURE 12. Solution breccia in lower solution zone of Little Tongue 

Member of Madison Limestone, unit 10 of Casper Mountain TV 

Tower section.

Thickness 

Feet Meters

orange; crossbedded, beds 0.1 0.3 ft 

thick; forms cliffy slope. Barren 

conodont samples 1, 12, 24, 36, 47, 67, 

and 100 ft above base and from upper 

foot (USGS 25913 25920-PC) ----- 106.0

3. Covered; tan sandy soil and rubble of 

sandstone blocks from unit above; 

forms slope below cliffy outcrops

2. Covered; tan sandy soil containing 

abundant quartz pebbles; forms saddle -------------------------------

32.3

30.0

15.0 4.6

Total thickness of Fremont Canyon Sandstone - 151.0 46.1

Precambrian granite:

1. Granite, pink, like that in Casper Mountain Road Section B.

BANNER MOUNTAIN SECTION

Section is located at rim of Lower Deer Creek Canyon 

on south flank of Banner Mountain in NWV4SWV4 

sec. 2, T. 31 N., R. 77 W., Converse County (fig. 13). 

Access to section is along jeep trail that follows power 

line that intersects Negro Hill Road in NW1 /4NW1 /4 

sec. 10. Section begins at top of Precambrian granite 

exposed on bench at altitude 7,050 ft and terminates on 

hillside strewn with dolomite in lower part of Big Goose 

Member of Madison Limestone. Section was measured 

with Jacobs staff and steel tape. Paleozoic section is 

well displayed in east wall of Lower Deer Creek 

Canyon (fig. 14).

Madison Limestone: 

Big Goose Member:

10. Covered and intermittent outcrops of 

silty dolomicrite weathering pale red 

and grayish yellow, beds regular to 

nodular, 0.1-0.3 ft thick; most beds 

faintly laminated; about 5 percent 

small varicolored chert nodules. 

Polygnathus inornatus, Patrognathus 

andersoni, and Bispathodus aculeatus 

9 ft above base (USGS 26009-PC). 

Outcrops become unreliable above 

this unit -------------------------- 40.0 12.2

Measured thickness of Big Goose Member

(incomplete) -------------------------- 40.0

Measured thickness of Madison Limestone (incomplete) --------------------------------- 40.0

Englewood Formation:

9. Dolomicrite; sandy; crinoidal; weathers 

yellowish gray; crinoidal debris as 

molds and casts and layers of quartz 

sand to very coarse size; beds 0.1 

0.5 ft thick. Rare spiriferoid brachiopods; Polygnathus inornatus

12.2

12.2
30 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO. 

R. 77 W. ___________________

EXPLANATION

Pennsylvanian

Casper Formation (part)

Mississippian to Devonian: 

Madison Limestone, Englewood Formation 

and Fremont Canyon Sandstone

Precambrian granite

Contact 

T Normal fault,hachured on downthrown side

Strike and dip of bedding 

^ Stratigraphic section traverse

500

I

1000 1500 FEET

_I

100 200 300

~Y 

400 METERS

FIGURE 13. Geologic sketch map of Steeple Pasture (1) and Banner Mountain (2) sections. Base 

from Banner Mountain 7.5' quadrangle. Contour interval is 100 feet.
STRATIGRAPHIC SECTION DESCRIPTIONS 31

FIGURE 14. Precambrian granite (pCg); Fremont Canyon Sandstone 

and Englewood Formation (MDef); Big Goose (Mmbg) and Little 

Tongue (Mmlt) Members of Madison Limestone; and Casper Formation (IPc) exposed in east wall of Lower Deer Creek Canyon near 

Banner Mountain and Steeple Pasture sections.

Thickness 

Feet Meters

(abundant), P. longiposticus, Pandorinellina n. sp., Patrognathus andersoni, and Siphonodella sp. 1 to 2 ft 

above base (USGS 26008-PC, BAH2, and BAH-3). This unit is same bed 

as unit 5 at Steeple Pasture -------- 3.0 0.9

8. Quartz sandstone; coarse- to very coarsegrained; dolomitic; weathers white to 

grayish orange; crossbedded, beds 

0.3-0.5 ft thick. Indeterminate 

conodonts (USGS 26007-PC). Disconformity at base of unit marks base of 

Mississippian --------------------- 1.3 0.4

7. Dolomicrite; sandy; weathers yellowish 

gray; beds irregular, 0.1-0.3 ft thick. 

Polygnathus communis carina, P. 

semicostatus, and Icriodus costatus? 

(USGS 26006-PC and BAH-1) ----- 1.5 0.5

6. Quartz sandstone; like unit 4 -------- 2.5 0.8

5. Covered; float from above ------------ 26.0 7.9

4. Quartz sandstone; coarse- to very coarsegrained; weathers white; crossbedded------------------------------- 1.5 0.5

3. Quartz sandstone and siltstone, interbedded; medium- to very coarsegrained quartz sand with siltstone 

pebbles up to 0.3 ft in diameter; 

weathers pale red; crossbedded, beds 

0.1-0.3 ft thick; lower part poorly exposed. Barren conodont sample 2 ft below top (USGS 26005-PC) --------- 9.0 2.8

Total thickness of Englewood Formation ------ 44.8 13.8

Thickness 

Feet Meters

Fremont Canyon Sandstone:

2. Quartz sandstone; medium- to very 

coarse-grained containing lenses of 

very coarse angular quartz pebbles up 

to 0.3 ft in diameter in lower 3 ft, perhaps deposited in depressions in 

underlying surface; weathers pale red 

to grayish red; crossbedded, beds 0.5 

3 ft thick. Barren conodont samples 

from lower 0.5 ft (USGS 26003-PC) 

and 10 ft above base (26004-PC) - - - 11.0 3.4

Total thickness of Fremont Canyon Sandstone - 11.0 3.4

Precambrian granite:

1. Granite; pink; equigranular; kaolinized 

feldspar in upper 5 ft; at least 2 ft of 

relief on top.

STEEPLE PASTURE SECTION

Section is located at rim of Lower Deer Creek Canyon 

just below Steeple Pasture in SV2NWV4 sec. 11, T. 31 

N., R. 77 W., Converse County (fig. 13). Access to section is along jeep trail to Steeple Pasture that intersects Negro Hill Road in NWV4 sec. 10. Section begins 

at top of Precambrian granite exposed on bench at altitude 6,800 ft and terminates on knob forming part of 

dipslope dipping into fault to north. Section was measured with Jacobs staff and steel tape.

Thickness 

Feet Meters

Casper Formation:

21. Dolomitic limestone; predominantly 

medium crystalline; like unit 17; some 

beds crinoidal; weathers yellowish 

gray, grayish yellow, grayish orange, 

and grayish red; beds 0.2-1 ft 

thick -----------------------------

20. Micrite and biomicrite; like unit 18. Barren foram sample USGS 26028-PC a 

foot above base --------------------

19. Dolomitic limestone; like unit 17; contacts gradational ------------------

18. Biomicrite; partly dolomitized; some 

beds in upper half crinoidal; olive gray 

weathering medium light gray to pale 

red; beds irregular, 0.1-0.3 ft thick; 

thin red-weathering partings in upper 

half. Indeterminate ostracodes in 

lower foot (USGS 26025-PC); foraminifers of Mamet Zone 25 or younger 

and the conodonts Idiognathodus sinuosis, Adetognathus lautus, and Hindeodus minutus 5 ft above base (USGS 

26026-PC, BAH-4); foraminifers of 

Mamet Zone 25 or younger a foot below top (USGS 26027-PC) ---------

10.0

2.0

1.5

3.0

0.6

0.5

12.0 3.7
32 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness 

Feet Meters

17. Dolomitic limestone; medium crystalline; weathers yellowish gray to 

grayish orange; beds 0.5-2 ft thick; 

forms cliffy slope ------------------ H.Q 3.4

Measured thickness of Casper Formation 

above Darwin Sandstone Member ------

Darwin Sandstone Member:

16. Quartz sandstone; fine-grained; calcareous; weathers white to grayish orange; poorly bedded, beds 0.2-4 ft 

thick; grades into unit above; prominent cliff-former. Barren conodont 

sample USGS 26024-PC from lower

foot ------------------------------

36.5 11.2

13.0 4.0

Total thickness of Darwin Sandstone Member ----------------------------------- 13.0 4.0

Measured thickness of Casper Formation (incomplete)------------------------------------- 49.5 15.2

Madison Limestone:

Little Tongue Member:

15. Biomicrite, pelsparite, oomicrite, and

oosparite; crinoidal; olive gray weathering medium light gray; beds 0.5-2 ft

thick; entire unit is collapse breccia

consisting of blocks as much as several

feet in diameter in red fine-grained

quartz sandstone matrix. Spiriferoid

brachiopods in lower 20 ft (USGS

26022-PC 15 ft above base) and foraminifers of Mamet Zone 9? 2 ft below

top (USGS 26023-PC) ------------- 35.0 10.7

14. Covered; rubble of limestone from above;

lower solution zone probably represented in lower part of unit, but no

solution breccia seen in float ------- 30.0 9.2

Total thickness of Little Tongue Member - 65.0 19.9 

Big Goose Member:

13. Dolomicrite; weathers yellowish gray;

some beds laminated; beds irregular,

0.3 1 ft thick; about 20 percent brown

chert lenses; poorly exposed -------- 18.0 5.5

12. Dolomicrite and micrite, interbedded;

about 50 percent of each; like unit 10;

about 10 percent brown chert lenses;

poorly exposed -------------------- 10.0 3.1

11. Micrite; partly dolomitized; olive gray

weathering medium light gray;

crinoidal; beds regular, 0.5-1 ft thick;

about 5 percent brown chert lenses;

forms ledge in slope. Indeterminate

brachiopods 3 ft above base (USGS

26020 PC); barren foram sample from

upper foot (USGS 26021-PC) ------ 14.0 4.3

10. Limestone and dolomite, interbedded;

like unit 9 but not brecciated although

some beds are shattered; about 5 percent chert; about 90 percent covered

on slope -------------------------- 15.0 4.6

Thickness

9. Micrite and pelsparite; olive gray weathering medium light gray; about 5 percent interbedded dolomite and 

dolomitic limestone, as in unit 7; beds 

0.5-2 ft thick; brecciated mostly in 

lower half (matrix is fine-grained carbonate); about 5 percent irregular 

brown chert. Barren foram samples

2 ft about base (USGS 26018-PC) and

3 ft below top (USGS 26019-PC) --- 

8. Covered and predominantly finegrained limestone float, some 

dolomite --------------------------

7. Dolomitic limestone and dolomite; predominantly medium crystalline; 

weathers yellowish gray to grayish orange; some fine-grained beds weather 

yellowish gray to pale red like those in 

unit 5; beds 0.3-1 ft thick; about 5-10 

percent irregular brown chert; some 

beds appear to be crossbedded; beds 

shattered and brecciated in upper 

half. A few beds contain poorly preserved brachiopods; silicified Vesiculophyllum sp. 15 ft above base; barren 

conodont sample USGS 26017-PC 

15 ft above base -------------------

6. Dolomicrite; silty; laminated; weathers 

pale red with grayish yellow streaks; 

beds nodular to regular, 0.3-1 ft thick; 

about 5 percent varicolored chert in 

thin stringers 5nd small nodules; 

about 90 percent covered on slope. Patrognathus andersoni, Siphonodella 

advanced sp., Pandorinellina n. sp. 

(Pa element), P. plumula, Hindeodus 

cf. H. cristulus, Bispathodus stabilis, 

and Polygnathus inornatus from lower 

foot (USGS 26013-PC); barren 

conodont samples 25 and 47 ft above 

base and from upper foot (USGS 

26014 26016-PC) ----------------

15.0

15.0

4.6

4.6

65.0 19.8

54.0 16.5

Total thickness of Big Goose Member ----- 206.0 

Total thickness of Madison Limestone -------- 271.0

63.0

82.9

Englewood Formation:

5. Dolomite; predominantly fine-grained; 

sandy; weathers yellowish gray with 

pale red streaks; beds 0.3-0.5 ft thick; 

poorly exposed; same bed as unit 9 at 

Banner Mountain. Disconformity at 

base of unit marks base of Mississippian ------------------------------

4. Quartz sandstone; coarse- to very coarsegrained; weathers white to moderate 

red; beds regular, 0.3-0.5 ft thick; 

poorly exposed. Barren conodont sample USGS 26012-PC 3 ft below top -

1.7

5.0

0.5

1.5
STRATIGRAPHIC SECTION DESCRIPTIONS 33

Thickness 

Feet Meters

3. Quartz siltstone and very fine-grained 

sandstone with scattered medium 

sand; platy; weathers pale red; exposed in trench. Barren conodont sample USGS 26011-PC 2 ft above 

base ------------------------------

2. Clay shale; silty; weathers grayish red; 

exposed in trench. Barren conodont 

sample USGS 26010-PC -----------

5.0

1.0

1.5

0.3

Total thickness of Englewood Formation ------ 12.7

Precambrian granite:

1. Granite; pink; equigranular; containing 

pegmatite veins; feldspars kaolinitized in upper 2-3 ft; relief on top not 

measurable; top exposed in trench.

3.8

BOX ELDER CANYON SECTION

Section begins near bottom of gorge at top of Precambrian granite (figs. 15, 16) exposed at altitude 5,950 ft 

in NV2NEV4 sec. 13, T. 32 N., R. 75 W., Converse 

County (fig. 17). Access to section is along jeep trail 

leading north from ranch house located just east of west 

boundary and on north boundary of SEV4 sec. 24. The 

ranch house is reached by dirt road that intersects Box 

Elder Road in NWV4 sec. 25. Section was measured 

with Jacobs staff and steel tape. The Paleozoic sequence is well displayed in the walls of the canyon, 

(fig. 18).

Thickness

Feet Meters

Casper Formation:

25. Quartz sandstone; like unit 23. Barren 

conodont sample USGS 26044-PC 

from lower foot. Section terminates in 

cliff; more section is exposed for about 

100 ft in notch in cliff to top of cliff -

24. Dolomitic limestone; like unit 20 -----

23. Quartz sandstone; like unit 21; beds 0.3- 

2 ft thick. Barren conodont sample 

USGS 26043-PC from lower foot ---

22. Dolomitic limestone; like unit 20; some 

pink stain ------------------------

21. Quartz sandstone; fine-grained; weathers pale red; crossbedded. Barren 

conodont sample USGS 26042-PC - -

20. Dolomitic limestone; medium crystalline; contains some bioclastic debris; pockmarked; weathers yellowish 

gray; beds irregular, 0.3-0.5 ft 

thick -----------------------------

Measured thickness of Casper Formation 

above Darwin Sandstone Member (incomplete) ---------------------------------

19.0 

2.0

4.0

14.0

3.0

7.5

5.8 

0.6

1.2

4.3

0.9

2.3

49.5 15.1

FIGURE 15. Fremont Canyon Sandstone (Df) resting on Precambrian granite (pCg) at Box Elder Canyon section. Hammerhead 

rests on top of granite.

Darwin Sandstone Member:

19. Quartz sandstone; fine-grained; calcareous; laminated; ripplemarked; 

weathers moderate pink -----------

18. Quartz sandstone; fine-grained; weathers white to moderate red (white and 

brown in lower third, middle third covered, red in upper third); crossbedded, 

beds 0.3-2 ft thick. Barren conodont 

sample USGS 26041-PC 50 ft above 

base ------------------------------

Total thickness of Darwin Sandstone Member -----------------------------------

Measured thickness of Casper Formation (incomplete) -------------------------------------

Madison Limestone:

Little Tongue Member:

17. Dolomite; fine-grained to medium crystalline; weathers yellowish gray; some 

beds laminated, some crossbedded; 

beds 0.5-1 ft thick; bioclastic (brachiopods); entire unit is riddled with 

solution cavities following vertical 

and horizontal joints and filled with 

fine-grained calcareous quartz sandThickness 

Feet Meters

4.0 1.2

56.0 17.1

60.0

109.5

18.3

33.4
34 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

FIGURE 16. Precambrian granite (pCg), Fremont Canyon Sandstone (Df), Englewood Formation 

(MDe), and Big Goose Member of Madison Limestone (Mmbg) at Box Elder Canyon section.

R. 75 W. R. 74 W. EXPLANATION

Pennsylvanian

Casper Formation (part)

Mississippian Madison Limestone

pCg ^ Precambrian granite

Mississippian to Devonian: 

Madison Limestone, Englewood Formation 

and Fremont Canyon Sandstone

0 500 1000 1500 FEET

Strike and dip of bedding 

< < < < Stratigraphic section traverse

0 100 200 300 400 METERS 

FIGURE 17. Geologic sketch map of Box Elder Canyon section. Base from Root Creek 7.5' quadrangle. Contour interval is 100 feet.

Thickness 

Feet Meters

stone weathering moderate red. Traverse offset about 70 yds west at top of 

unit to better outcrops of overlying 

units ----------------------------- 16.0 4.9

16. Limestone collapse breccia; micrite, 

biomicrite, intrasparite, and oosparite; olive gray weathering medium 

light gray; beds regular, 0.5-1 ft

Thickness 

Feet Meters
STRATIGRAPHIC SECTION DESCRIPTIONS 35

FIGURE 18. Precambrian granite (pCg); Fremont Canyon Sandstone (Df); Englewood Formation 

(MDe); Big Goose (Mmbg) and Little Tongue (Mmlt) Members of Madison Limestone; and 

Casper Formation (IPc) exposed in east wall of Box Elder Canyon near section traverse.

Thickness 

Feet Meters

thick; entire unit is brecciated into 

large blocks; matrix is fine-grained 

calcareous quartz sandstone weathering light red; where bedded, bedding is 

undulant; about 10 percent brown 

chert nodules and stringers. Large 

spiriferoid brachiopods throughout 

(USGS 26040-PC from 10 ft above 

base) ----------------------------- 30.0 9.2

15. Limestone solution breccia; angular 

clasts of micrite (olive gray weathering medium light gray) in matrix of 

fine-grained calcareous quartz sandstone weathering light red; clasts 

mostly 0.2 ft or less in diameter, some 

up to 2 ft. Upper part of lower solution 

zone ------------------------------ 11.0 3.4

14. Dolomite solution breccia; angular 

clasts of fine-grained dolomite weathering yellowish gray in matrix of calcareous siltstone weathering grayish 

orange; clasts mostly 0.1 ft or less in 

diameter, some up to 1 ft; about 5-10 

percent brown chert clasts; at top is an 

irregular lens of fine-grained quartz 

sandstone weathering white to dark 

yellowish orange filling a solution 

cavity 4 ft high and 30 ft wide; another 

smaller lens at base. Lower part of 

lower solution zone ---------------- 28.0 8.5

Total thickness of Little Tongue Member - 85.0 26.0

Thickness 

Feet Meters

Big Goose Member:

13. Dolomite; like unit 11; mostly shattered;

about 20-30 percent brown chert

mostly in stringers; poorly exposed in

lower half, cliffy in upper half 60.0 18.3 

12. Covered; fine-grained to medium crystalline dolomite in float ------------ 10.0 3.1

11. Dolomite; fine-grained to medium crystalline; shattered; weathers yellowish

gray; beds 0.3-0.5 ft thick; about 30

percent irregular networks and sheets

of brown chert; a lens of fine-grained

quartz sandstone weathering dark

yellowish orange in solution cavity 1.5

ft high and 5 ft wide 5 ft below top - 25.0 7.6 

10. Dolomitic limestone and dolomite; interbedded fine- and medium-grained;

bioclastic (molds and casts of brachiopods); weathers yellowish gray;

beds mostly regular, 0.1-1 ft thick;

some coarse-grained beds having

small-scale crossbedding; unit forms

cliffs ----------------------------- 19.0 5.8

9. Pelbiosparite; algal (cysts); olive gray

weathering medium light gray; beds

regular, 0.5-2 ft thick. Barren foram

sample USGS 26039-PC 3 ft above"

base; lower part of cliff ------------ 7.0 2.1

8. Dolomite; fine-grained; weathers yellowish gray; crossbedded, beds 0.3-1 ft

thick. Barren conodont sample from

upper foot (USGS 26038-PC) ------ 5.0 1.5
36 PALEOZOIC STRATIGRAPHY AND HISTORY, NORTHERN LARAMIE RANGE, SE. WYO.

Thickness 

Feet Meters

1. Dolomicrite; silty; with rare layers of 

bioclastic debris; weathers yellowish 

gray; many beds laminated; beds regular to irregular, 0.3-1 ft thick; about 

10 percent small, irregular, moderatered nodules and stringers of chert in 

lower half. Undetermined brachiopods 

from lower foot (USGS 26037-PC) --

6. Dolomitic limestone; medium- to coarsegrained; bioclastic (molds and casts); 

weathers yellowish gray; crossbedded, 

beds 0.5-1 ft thick ----------------

5. Covered and rubble from above; finegrained dolomite in place at top

34.0

3.0

10.5

10.4

0.9

3.2

Total thickness of Big Goose Member -- 173.5 52.9 

Total thickness of Madison Limestone -------- 258.5 78.9

Englewood Formation:

4. Quartz sandstone; predominantly

coarse- to very coarse-grained, with

some pebbles up to 5 mm in diameter;

calcareous; friable to hard; weathers

white to pale red; crossbedded, beds

0.3-0.5 ft thick; thin beds of quartz

siltstone like unit 3, 2 ft above base.

Polygnathus experplexus and P. sp. 2 ft

above base (USGS 26036-PC) ------ 9.0 2.8

3. Covered and a few outcrops of platy calcareous quartz siltstone and finegrained sandstone weathering pale

red to moderate red; entire interval

seems to be of this lithology; outcrops

mostly in lower half. Barren conodont

sample USGS 26035-PC from lower

foot ------------------------------ 24.0 7.3

Total thickness of Englewood Formation ------ 33.0 10.1

Fremont Canyon Sandstone:

2. Quartz sandstone; predominantly 

coarse- to very coarse-grained with 

thin lenses containing pebbles up to 

15 mm in diameter at base; friable to 

hard; weathers white to moderate 

brown; crossbedded, beds 0.2-2 ft 

thick; some beds have greenishweathering shaly partings; forms 

massive cliff. Barren conodont samples from lower foot (USGS 26029- 

PC), from 10,21.5,30,40 ft above base 

(USGS 26030 26033-PC), and from 

upper foot (USGS 26034-PC) ------ 48.0 14.6

Total thickness of Fremont Canyon Sandstone ------------------------------------- 48.0 14.6

Precambrian granite:

1. Granite; pink; equigranular; kaolinized 

feldspars in upper 3 ft; about 2 ft of 

relief on top.

HARTVILLE CANYON SECTION

Section is located on south-facing nose immediately 

east of North Platte River below Guernsey Reservoir in 

SV2NEV4 sec. 27, T. 27 N., R. 66 W., Platte County. 

Section begins at or near base of Fremont Canyon 

Sandstone at base of nose (Precambrian granite is exposed in draw just east of nose) and proceeds westward 

up nose to top of Madison Limestone exposed on dipslope. Access to section is by dirt road leading westward 

from main road up Hartville Canyon. Section measured with steel tape. No samples were collected here.

This section location appears to be at or very near the 

location described by Smith (1903, p. 2) as representative of the Guernsey Formation, which included all the 

beds from the top of the Precambrian granite to the 

base of the Hartville Formation. We regard the section 

as the type section of the Guernsey Formation.

Hartville Formation:

Darwin Sandstone Member:

12. Quartz sandstone; fine- to mediumgrained; weathers red; crossbedded; 

rests unconformably on unit below; at 

least 25 ft exposed (not measured).

Madison Limestone:

Little Tongue Member:

11. Limestone, fine- to medium-grained, 

and dolomite, medium crystalline; 

cherty; dolomite is in lower 10 ft only; 

medium-bedded; red-weathering siltstone and sandstone fills solution cavities following vertical and horizontal 

joints; forms cliffy outcrop ---------

Total thickness of Little Tongue Member - 

Big Goose Member:

10. Dolomite; fine-grained; silty, shattered; 

weathers yellowish; thin-bedded; top 

irregular -------------------------

9. Dolomitic limestone; fine-grained; 

weathers yellowish; shattered and 

contorted; contains red siltstone and 

sandstone solution cavity fillings

8. Limestone; fine-grained; weathers pink 

and gray; passes laterally into coarsegrained dolomitic limestone; single 

bed -------------------------------

7. Dolomitic limestone; fossiliferous; 

medium-bedded; laminated; weathers 

yellowish -------------------------

Total thickness of Big Goose Member ----- 

Total thickness of Madison Limestone --------

Englewood Formation:

6. Quartz siltstone; calcareous; platy; 

weathers purplish -----------------

Thickness 

Feet Meters

29.0 8.9

29.0

3.0

5.5

4.0

11.0

8.9

0.9

1.7

1.2

3.4

23.5

52.5

7.2 

16.1

5.0 1.5
REFERENCES CITED 37

Thickness

5. Quartz siltstone; predominantly calcareous, some beds dolomitic; some 

beds oolitic; weathers yellowish; beds 

regular, thin ----------------------

4. Quartz siltstone; calcareous; thinbedded; weathers yellowish --------

3. Quartz siltstone and fine-grained sandstone; thin- to medium-bedded; weathers red. Silicified brachiopods and rare 

Vesiculophyllum sp. ---------------

2. Quartz siltstone; calcareous; thinbedded; weathers yellowish --------

Feet

11.0

5.0

5.0

6.5

Meters

3.4 

1.5

1.5 

2.0

Total thickness of Englewood Formation ------ 32.5

Fremont Canyon Sandstone:

1. Quartz sandstone; coarse- to very coarsegrained; weathers brown; crossbedded -------------------------------

9.9

6.0

Total thickness of Fremont Canyon Sandstone - 6.0

Precambrian granite:

Granite; pink; equigranular; exposed in draw 

east of traverse.

REFERENCES CITED

Baars, D.L., 1972, Devonian System, in Mallory, W.W., ed., Geologic 

atlas of the Rocky Mountain region: Denver, Rocky Mountain 

Association of Geologists, p. 90-99, 8 figs.

Blackwelder, Eliot, 1918, New geological formations in western Wyoming: Washington Academy of Science Journal, v. 8, no. 13, 

p. 417-426.

Block, D.A., 1952, The geology of the Deadwood Formation between 

Bear Butte and Spring Creeks, Black Hills, South Dakota: Unpub. M.A. thesis, State University of Iowa, 40 p., 6 figs.

Campbell, J.A., 1970, Stratigraphy of the Chaffee Group (Upper Devonian), west-central Colorado: American Assocation of 

Petroleum Geologists Bulletin, v. 54, no. 2, p. 313-325, 15 figs.

 , 1972, Petrology of the quartzose sandstone of the Parting 

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