Cambrian Stratigraphy of the 

Wendover Area, Utah and Nevada

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Cambrian Stratigraphy of the 

Wendover Area, Utah and Nevada

By LINDA B. McCOLLUM and DAVID M. MILLER

New lithofacies of Cambrian strata in the 

northeastern Great Basin are assigned to 

nineteen formations, ten of them new

U.S. GEOLOGICAL SURVEY BULLETIN 1948
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names

in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

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For sale by the

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Library of Congress Cataloging-in-Publication Data

McCollum, Linda B.

Cambrian stratigraphy of the Wendover area, Utah and Nevada / by 

Linda B. McCollum and David M. Miller.

p. cm. (U.S. Geological Survey bulletin : 1948) 

Includes bibliographical references. 

Supt. of Docs, no.: I 19.3:1948

1. Geology, Stratigraphic Cambrian. 2. Geology Utah. 

3. Geology Nevada. I. Miller, David M. (David MacArthur), 1951- 

. II. Title. III. Title: Wendover Area, Utah and Nevada. 

IV. Series. 

QE75.B9no. 1948 

[QE656] 

557.3 s dc20

[551.7'23'09792] 90-21966

CIP
CONTENTS

Abstract 1 

Introduction 1

Structural setting 3

Acknowledgments 4 

Overview of the stratigraphic nomenclature 

Prospect Mountain Quartzite 6 

Killian Springs Formation (new) 6 

Toano Limestone (new) 13 

Clifside Limestone (new) 17 

Morgan Pass Formation (new) 18 

Decoy Limestone (new) 19 

Shatter Formation (new) 20 

Lion Spring Limestone (new) 23 

Ola Sandstone (new) 23 

Goshute Limestone (new) 23 

Oasis Formation (new) 24 

Dunderberg Shale 25 

Upper-plate Cambrian section 26 

Trippe Limestone 26 

Lamb Dolomite (emended) 26 

Big Horse Limestone 27 

Candland Formation 27 

Johns Wash Limestone 28 

Corset Spring Shale 28 

Notch Peak Formation 28 

Depositional environments 29 

References cited 31 

Measured sections 34

FIGURES

1. Map of eastern Nevada and western Utah showing Cambrian outcrops 2

2. Simplified geologic map of Wendover area 3 

3-5. Charts showing:

3. Columnar sections of Cambrian units in Wendover area 5

4. Stratigraphic terminology for Cambrian section in central Silver Island 

Mountains 7

5. Correlations of Cambrian formations in northern and central Great

Basin 8 

6. Map showing distribution of Cambrian stratigraphic units in Wendover

area 10 

7-9. Geologic maps showing:

7. Part of Pilot Range 12

8. Toano Range north of Silver Zone Pass 14

9. Tetzlaff Peak area in central Silver Island Mountains 15

Contents III
10. Photographs showing soft-sediment slumps in the Toano Limestone 16

11. Photographs showing Toano Limestone soft-sediment features 17

12. Geologic map of Morgan Pass area in northern Goshute Mountains and 

southern Toano Range 19

13. Photograph of Morgan Pass section 20

14. Geologic map of Toano Range south of Silver Zone Pass 21

15. Photograph of stromatolites, Morgan Pass Formation 22

16. Photograph showing Upper Cambrian section, central Silver Island 

Mountains 24

17. Geologic map of Jenkins Peak area in central Silver Island Mountains 25

IV Contents
Cambrian Stratigraphy of the Wendover Area, 

Utah and Nevada

By Linda B. McCollum1 and David M. Miller 

Abstract

A Cambrian stratal sequence, approximately 4,000 meters thick, is exposed in the Toano Range, Pilot Range, Goshute 

Mountains, and Silver Island Mountains along the northern 

Utah/Nevada state line. This sequence is divided into 19 formations, 10 of which are newly proposed herein. Newly described formations are the Lower and Middle Cambrian Killian 

Springs Formation; the Middle Cambrian Toano Limestone, 

Clifside Limestone, Morgan Pass Formation, and Decoy Limestone; the Middle and Upper Cambrian Shafter Formation; 

and the Upper Cambrian Oasis Formation, Lion Spring Limestone, Ola Sandstone, and Goshute Limestone. In addition, 

the Late Proterozoic and Lower Cambrian Prospect Mountain 

Quartzite; the Middle Cambrian Trippe Limestone; the Upper 

Cambrian Lamb Dolomite, Big Horse Limestone, Candland 

Formation, Johns Wash Limestone, Corset Spring Shale, and 

Dunderberg Shale; and the Upper Cambrian and Lower Ordovician Notch Peak Formation are present in the Wendover 

region.

The new nomenclature reflects substantial lithologic differences, particularly in the Middle to Upper Cambrian strata, 

of the Wendover region compared with other stratigraphic 

sections in the Great Basin. Complex facies patterns within 

the Middle to Upper Cambrian sequence, and subsequent 

structural telescoping of strata by the Pilot Peak detachment 

fault, require a dual and partially equivalent formational nomenclature. In addition, the Dunderberg Shale in the Toano 

Range and Goshute Mountains is temporally equivalent to the 

Candland Formation, Johns Wash Limestone, and Corset Spring 

Shale in the Pilot Range and Silver Island Mountains.

A wide range of depositional environments is recorded 

by the Cambrian sequence in the Wendover region. Braided 

alluvial-plain to shallow-marine clastic strata of the Prospect 

Mountain Quartzite are conformably overlain by prodelta and 

basinal, mixed clastic strata of the Killian Springs Formation. 

The overlying Toano Limestone was deposited on a northwest-facing, distally steepened carbonate ramp. The Clifside 

Limestone represents an algally dominated carbonate platform that prograded northwestward.

A mixed clastic and carbonate environment developed 

across the carbonate platform during deposition of the MorManuscript approved for publication, June 18, 1990. 

'Geology Department, Eastern Washington Univ., Cheney, 

WA 99004

gan Pass Formation. The cessation of clastic input resulted in 

deposition of the Decoy Limestone, followed by a widespread 

marine transgression, which resulted in drowning of the outer 

platform. Cosmopolitan agnostoid trilobites in thin-bedded 

limestone and calcareous siltstone of the Shafter Formation 

indicate an open-marine environment outboard of the carbonate-platform deposits of the Lamb Dolomite. The carbonate platform again prograded completely across the region, 

and mixed limestone, dolomite, and sandstone accumulated. 

The Big Horse Limestone to the north, the Oasis Formation to 

the west, and the Lion Spring Limestone, Ola Sandstone, and 

Goshute Limestone to the south reflect these changes.

The Candland Formation and Dunderberg Shale record 

the last major regional transgression of the Cambrian and the 

return of open-marine conditions. A carbonate platform became reestablished with the deposition of the Johns Wash 

Limestone and the overlying Corset Spring Shale. That carbonate platform continued throughout the region with deposition of the Notch Peak Formation.

INTRODUCTION

Cambrian rocks are exposed in more than a dozen 

mountain ranges in the northern Great Basin (fig. 1). Near 

the town of Wendover, astride the Utah/Nevada border, 

Cambrian strata crop out over much of the Toano Range 

both north and south of Silver Zone Pass, at the junction of 

the Toano Range and the Goshute Mountains, in the southern and central Pilot Range, and in the central and northern 

Silver Island Mountains (fig. 2). Although a complete, continuous Cambrian section is not preserved at any one locality, 

a composite section of strata has an aggregate thickness of 

approximately 4,000 m. A complete, although structurally 

thinned, section was recently discovered by Phyllis Camilleri 

(unpub. mapping, 1990) in the Pequop Mountains 15 km 

west of the Toano Range.

Cambrian sections exposed in the Wendover region 

differ in several respects from the Cambrian sections originally established to the south by Walcott (1908a, b) in the 

House Range, including subsequent nomenclature changes 

(Hintze and Robison, 1975; Hintze and Palmer, 1976), and 

by Nolan (1935) in the Deep Creek Mountains (fig. 1). The 

stepped appearance in eroded profile of alternating carbonate cliffs and mixed clastic and carbonate slope-forming

Introduction
116° 115° 114°

42°

41 c

40°

39°

IDAHO ~r IJ^

<\

Q I X

East

Humboldt 

Range

Wood 

Hills

Pequop - t MIS

Mountains r-^i,,,^ Crosnute ,AI ,

i'Mts Wendover

* Silver Island 

Mts

Area of figures 

2 and 6

Fish 

Creek 

Range

100 KILOMETERS

Figure 1. Index map of eastern Nevada and western Utah showing outcrops of Cambrian 

rocks (shaded).

2 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
units that is so typical of Middle Cambrian strata in those 

classic sections is absent in much of the Wendover region. 

Instead, sequences here are composed of slope-forming 

clastic and carbonate rocks. Only near plutons do the rocks 

form a more resistant topography, where they are highly 

recrystallized and metamorphosed. The sections of Upper 

Cambrian strata in the Wendover region form the more 

typical cliff-slope couplets and are recognizable within the 

context of established formations in the central Great Basin. However, as noted by Hintze and Palmer (1976, p. G4), 

regionally the lower half of the Upper Cambrian sequence 

is lithologically highly variable, is fossiliferous, and has 

been assigned a varied nomenclature.

In this paper we describe the Cambrian sections exposed in the Wendover area, name 10 formations, interpret 

depositional environments, and place these environments 

within a regional context This report is an outgrowth of a

regional study of the Cambrian outer-shelf environments in 

the Great Basin by McCollum and of recent detailed geologic mapping within the Pilot Range, northern Toano Range, 

and Silver Island Mountains by Miller and his associates.

Structural Setting

The Wendover region lies within a prominent eastward sigmoidal bend of Paleozoic facies and structural 

trends. This feature has been interpreted variously as (1) an 

irregularity on the Paleozoic continental margin (Stevens, 

1981; Hurst and others, 1985), (2) the result of right-lateral 

displacement of as much as 65 km during the Jurassic to 

Early Cretaceous along the hypothetical Wells fault (Thorman, 1968, 1970; Thorman and Ketner, 1979), and (3) the 

result of cumulative Mesozoic oroflexural bending of as

113°45'

Area of 

V figure 17

Area of 

figure9

EXPLANATION

Volcanic and sedimentary 

rocks (Cenozoic)

Granite (Cenozoic 

and Mesozoic)

Clastic and carbonate rocks 

(Triassic to Mississippian)

Carbonate rocks (Devonian 

to Ordovician)

Carbonate rocks and shale 

(Cambrian)

Clastic rocks (Lower

Cambrian and Late

Proterozoic)

Contact

Figure 2. Simplified geologic map of Wendover region, northeastern Nevada and northwestern Utah. Modified from 

Miller (1984) and Day and others (1987). See figure 1 for location.

Introduction
much as 120 km across the northern Great Basin (Stewart 

and Poole, 1974).

The most prominent structure in the study area is 

the Pilot Peak detachment, a major low-angle normal fault 

exposed in the Pilot Range (fig. 2). This fault separates a 

metamorphosed Late Proterozoic to Middle Cambrian sequence below from a slightly metamorphosed to unmetamorphosed Upper Cambrian to Lower Permian sequence 

above (Miller, 1983, 1984; Snoke and Miller, 1988). A 

similar detachment fault is present in the northern Toano 

Range, where it separates a lower plate, Late Proterozoic to 

Ordovician metamorphosed sequence from an unmetamorphosed Upper Cambrian to Permian sequence (Click, 1987). 

At Tetzlaff Peak in the central Silver Island Mountains, a 

high- to low-angle fault separates a metamorphosed Cambrian section from relatively unmetamorphosed Ordovician 

and younger rocks (Schaeffer, 1960; D.M. Miller, 1988, 

unpubl. mapping).

Locally, all of the Cambrian facies vary over relatively short distances within and between ranges, probably 

as a result of rapidly shifting conditions of deposition at the 

seaward edge of a carbonate platform. It remains unclear to 

what extent telescoping by major Mesozoic structures and 

Tertiary extension have affected the original distribution of 

facies. Lower to Middle Cambrian facies of the metamorphosed sequence in the Wendover area differ markedly from 

the nearest temporally equivalent section just 60 km to the 

south, located near Gold Hill in the Deep Creek Mountains, 

Utah (McCollum and McCollum, 1984). Ultimately, an integration of Paleozoic facies patterns with Mesozoic and 

younger structures must be used to determine the most likely 

original paleogeographic configuration.

Acknowledgments

We greatly appreciate the efforts of several individuals who have added materially to the report. Michael 

B. McCollum aided us throughout the study. Richard A. 

Robison identified the Middle Cambrian fossils and made 

important collections in the Silver Island Mountains and 

Toano Range. Allison R. Palmer identified numerous Late 

Cambrian collections. Collections of Late Cambrian inarticulate brachiopods were identified by A.J. Rowell. John 

M. Repetski identified Late Cambrian conodont faunas. J. 

Keith Rigby examined sponge collections from the Pilot 

Range. Lehi F. Hintze visited the area and aided with regional Cambrian-Ordovician correlations. Mary L. Droser 

spent several days studying the ichnofabric patterns of the 

Cambrian and Ordovician carbonate section. Field observations of the Prospect Mountain Quartzite and the Killian 

Springs Formation in the Silver Island Mountains by Jeffrey 

F. Mount were very instructive. Linda L. Click delimited 

the Cambrian stratigraphy in the northern Toano Range and 

guided us through these sections. Phyllis Camilleri recognized a Cambrian section in the Pequop Mountains and 

guided us through it. We are grateful to Keith B. Ketner 

and Michael E. Taylor for discussion of the Cambrian section of the Morgan Pass area in the northern Goshute 

Mountains. Able field assistance was rendered to McCollum by Mark W. Ansell and William M. Schneck.

OVERVIEW OF THE STRATIGRAPHIC 

NOMENCLATURE

The Paleozoic stratigraphy in the Wendover region 

was originally established as an outgrowth of geologic 

mapping by Anderson (1957, 1960) and Schaeffer (1960) 

in the Silver Island Mountains, by O'Neill (1968) in the 

Pilot Range, and by Pilger (1972) in the Toano Range. 

Strata in the Silver Island Mountains were included in a 

regional correlation of Upper Cambrian stratigraphy by 

Bentley (1958), and the faunas were studied by Robison 

(1960). Formational nomenclature for the Cambrian System used in these studies was largely adopted from that 

established to the south in the House Range by Walcott 

(1908a, b) and in the Deep Creek Mountains by Nolan 

(1935). However, these Cambrian correlations (fig. 3) were 

hampered by the remoteness from established sections, 

complex facies changes, poorly preserved and misidentified 

faunas, structural dislocations, plutonic disruptions, and lowgrade metamorphism.

Anderson (1957,1960) divided a highly faulted and 

incomplete Cambrian section at Crater Island in the northern Silver Island Mountains into six previously established 

formations and two undifferentiated or questionably assigned 

units. A more complete Cambrian section, exposed between 

Tetzlaff Peak and Jenkins Peak within the central Silver 

Island Mountains, was divided by Schaeffer (1960) into 13 

previously established formations. Schaeffer's upper Middle 

Cambrian section was revised as Upper Cambrian by Robison and Palmer (1968), based on faunal reidentifications 

and additional collections. Palmer (1971, p. 50) later called 

for a complete reevaluation of the Cambrian stratigraphy 

near Wendover, and recent geologic mapping in the surrounding mountain ranges has confirmed this need (Miller 

and Lush, 1981; D.M. Miller and others, 1982; Glick, 1987).

A partial Cambrian section was identified by O'Neill 

(1968) in the highly faulted southern Pilot Range (fig. 2). 

O'Neill recognized that the Prospect Mountain Quartzite 

underlies Pilot Peak and assigned overlying black to purple 

phyllite to the Pioche Shale. He divided succeeding Cambrian silty limestones into four informal units and three 

previously designated formations: the Upper Cambrian 

Dunderberg Shale, Johns Wash "Formation," and Notch Peak 

Formation.

Cambrian rocks are extensively exposed within the 

northern half of the Toano Range. In the Silver Zone Pass 

area, Pilger (1972) mapped the Prospect Mountain Quartz4 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
ite and assigned the overlying dark, argillaceous sedimentary rocks to the Pioche Shale. He divided the Cambrian 

carbonate section into informal units A and B, overlain by 

the Upper Cambrian Notch Peak Formation. To the north,

Coats (1987) showed undifferentiated Cambrian rocks within 

much of the Toano Range. Glick (1987) adopted the Cambrian nomenclature proposed by McCollum and McCollum 

(1984) for the metamorphosed Cambrian section in the

Toano Range near 

Silver Zone Pass

Pilot Range Central Silver 

Island Mountains

Goshute Mountains 

near Morgan Pass

o -1

Figure

shown

Silly shale

3. Columnar sections of Cambrian units in Wendover area. Thickness and lithology are portrayed; ages of units 

for Toano Range section only.

Overview of the Stratigraphic Nomenclature 5
northern Toano Range, and she introduced the Orr Formation into the Toano Range for part of the unmetamorphosed, 

Middle and Upper Cambrian section.

The southern Toano Range and northern Goshute 

Mountains were recently mapped by Day and others (1987) 

in conjunction with studies of proposed wilderness areas 

(Ketner and others, 1987). The Middle and Upper Cambrian section below the Notch Peak Formation exposed at 

Morgan Pass at the junction of the two ranges was designated as informal units A through H, in descending order 

(Day and others, 1987). Taylor and others (1986), Taylor 

(1987), and Drumheller (1990) reported on the depositional 

environment and faunal content in part of that section below 

the Notch Peak Formation.

The formational scheme devised in this paper reflects complex facies changes within and between mountain ranges in the Wendover region. Cambrian sequences 

exposed in the Great Basin reflect a wide range of facies 

variation, and over 100 formational designations exist 

(Palmer, 1971). Historically, this nomenclature has grown 

as a result of the individual needs of local geologic mapping projects, with rather limited appreciation of regional 

facies similarities and differences. A special attempt is made 

in this paper to establish a formational nomenclature that 

accommodates both the local mapping needs, often affected 

by substantial facies variations, and the recognition of regionally extensive units that can be adopted locally.

The Cambrian section exposed in the Wendover region is estimated to be nearly 4,000 m thick, although no 

complete section extending from the base of the Prospect 

Mountain Quartzite to the top of the Notch Peak Formation 

is exposed at any single locality. The most complete Cambrian section is exposed near Silver Zone Pass in the Toano 

Range. Less complete Cambrian sections are present near 

Morgan Pass at the junction of the southern Toano Range 

and the northern Goshute Mountains, in the central Pilot 

Range, and in the central and northern Silver Island Mountains (fig. 2).

The Cambrian sequence exposed in these ranges is 

divided into 19 formations, 10 of which are new and are 

formally named and defined in this report. The new formations are the Killian Springs Formation, Toano Limestone, 

Clifside Limestone, Morgan Pass Formation, Decoy Limestone, Shafter Formation, Oasis Formation, Lion Spring 

Limestone, Ola Sandstone, and Goshute Limestone. Established formations that have either previously been used or 

are herein geographically extended into the Wendover region are the Prospect Mountain Quartzite, Trippe Limestone, Lamb Dolomite, Big Horse Limestone, Candland 

Formation, Johns Wash Limestone, Corset Spring Shale, 

Dunderberg Shale, and Notch Peak Formation (fig. 3).

Much of the Cambrian nomenclature previously used 

for the Wendover region was either inappropriate or inadequate, in many cases consisting of informal unit designations. We present previous formal unit designations and

propose changes in the Silver Island Mountains (fig. 4) and 

also present regional correlations (fig. 5). The distribution 

in the Wendover region of the Cambrian units used in this 

report is depicted in figure 6. Further comments regarding 

nomenclature, age, and regional correlations can be found 

under the discussion of each formation below.

PROSPECT MOUNTAIN QUARTZITE

The cliff-forming Late Proterozoic and Lower Cambrian Prospect Mountain Quartzite has been recognized 

throughout the central Great Basin. The Prospect Mountain, 

originally named by Hague (1883), was redefined by Nolan 

and others (1956) for exposures near Eureka, Nevada, where 

the lower half of the formation is either covered or structurally removed. A complete reference section of the Prospect 

Mountain Quartzite was described by Misch and Hazzard 

(1962) in the Snake Range and later modified by Hose and 

Blake (1976).

Quartz arenite is the dominant lithology of the Prospect Mountain Quartzite, followed by subarkose, argillite to 

siltite, and quartzite-pebble conglomerate. The white to lightgray quartz arenite is generally fine to medium grained and 

crossbedded. Quartzite-pebble conglomerate is present as 

channel lags and in tabular sheets. Subarkose is common in 

several intervals, with microcline being the predominant 

feldspar.

A complete section of the Prospect Mountain 

Quartzite, approximately 955 m thick, is exposed on Pilot 

Peak (Miller, 1983). The uppermost 430 m of the Prospect 

Mountain Quartzite are exposed near Tetzlaff Peak in the 

central Silver Island Mountains (Schaeffer, 1960). A faulted 

section, approximately 350 m thick, is present in the Toano 

Range north of Silver Zone Pass (Glick, 1987).

KILLIAN SPRINGS FORMATION (NEW)

The Killian Springs Formation is exposed on the 

flanks of Pilot Peak in the central Pilot Range (fig. 7), near 

Silver Zone Pass in the Toano Range (fig. 8), and on the 

north flank of Tetzlaff Peak in the Silver Island Mountains 

(fig. 9). It consists of strata previously assigned to the Pioche Shale by Schaeffer (1960) in the Silver Island Mountains, by O'Neill (1968) in the Pilot Range, and by Pilger 

(1972) in the Toano Range, and strata assigned to the Pioche 

Formation of Hintze and Robison (1975) by Miller and 

Lush (1981) in the Pilot Range. The Killian Springs Formation is here named for a 300-m-thick sequence of interbedded clastic and minor carbonate rocks exposed between 

Killian Springs and Cottonwood Springs on the west side 

of the Pilot Range in sec. 21, T. 5 N., R. 19 W., Patterson 

Pass 7/2-minute quadrangle, Box Elder County, Utah (fig. 

7); these rocks are designated as the type section of the

6 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Central Silver Island Mountains

Schaeffer 

(1960)

Robison and Palmer 

(1968) This paper

Jenkins Peak section

Notch Peak Formation 

568m 1864ft

Weeks Formation 

95 m 309 ft

Marjum Limestone 

88 m 290 ft

Wheeler Shale 

85 m 279 ft

Restricted Swasey 

94 m Limestone 307 ft

Condor Formation 

81 m 265 ft

Dome Formation? 

108m 355ft

Millard Ls.-Burrows Ls.?- 

Burnt Canyon Ls.?, 

undifferentiated

/^s^NX%^%XSx^SX\X%^Sy

Covered interval

Notch Peak Formation

Corset Spring Shale

Johns Wash Limestone

Dunderberg Shale

Lower Upper Cambrian, 

undifferentiated

'SXSXS/\/X/X/S-XS/S/s

Covered interval

Notch Peak Formation 

500m 1640ft

16m Corset Spring Shale 52ft

Johns Wash Limestone 

80 m 262 ft

Candland Formation 

85 m 279 ft

Big Horse 

Limestone

175m 574ft

Lamb Dolomite

130m 426ft 

«/NX^X^-^XX/N/SNX^XSXX

Covered interval

Tetzlaff Peak section

Covered interval

Millard Ls.-Burrows Ls.?- 

Burnt Canyon Ls.?, 

undifferentiated

542m 1779ft

Covered interval

Busby Quartzite 

42+ m 142+ ft

Pioche Shale 

87 m 285 ft

Prospect Mountain 

Quartzite 

428+ m 1403+ ft

Not 

discussed

Covered interval 

Toano Limestone

375+ m 1230+ ft 

Covered interval

Killian Springs 

Formation

166+m 545+ ft

Prospect Mountain 

Quartzite

Figure 4. Comparison of published and proposed stratigraphic terminology for Cambrian 

section in central Silver Island Mountains, Utah.

Killian Springs Formation (New)
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Pp

Formation

Corset Spring 

Shale

D C 

PA

Cr

B

C 

L

L A

Patterson 

Pass 

Shale

Pole 

Canyon 

Limestone

P

Pioche 

Shale

Prospect 

Mountain 

Quartzite

Not 

exposed

Southern 

Snake Range, 

Nevada

Drewes and 

Palmer (1957); 

Palmer (1971); 

Whitebread (1969); 

Robison (1984)

House Limestone

Notch Peak 

Formation

El Corset Spring Sh.

El

| Formation Lincoln Peak

Gy 

G

Johns Wash Ls.

D

PA 

Upper

shale

member 

C

L

L Middle 

Is. mbr.

Lower 

Pp 

shale

member 

Pa

Pg

Pole 

Canyon 

Limestone

Pioche 

Shale

Prospect 

Mountain 

Quartzite

McCoy Creek 

Group 1

Central 

House Range, 

Utah

Hintze and 

Palmer (1976); 

Hintze and 

Robison (1975); 

Hintze and 

others (1988)

House Limestone 

Sy rw

Peak Notch Fm.

C

Orr Formatic

C 

C 

C

L

Pp

Pp Pp Pp Pp

Pa 

Pa

Pa 

Pg

Gy

E

E

G 

G

A

Pioche Fm.

/**

5 Lava Dam Mbr.

s Red Tops Mbr

Hellnmaria 

Mbr.

T

T Sneakover 

Ei Ls. Mbr.

Ei Corset Spring 

^-v Sh.Mbr.y 

Johns Wash Ls. Mbr

D CandlandSh. 

PA Member

Cr Big Horse 

Cr Ls. Mbr. 

C

Weeks 

Limestone

Marjum 

Formation

Wheeler 

Shale

Swasey Ls.

Whirlwind Fm.

Dome Ls.

Chisholm Fm.

Howell 

Limestone

A 

p Tatow Mbr.

0 Lower mbr.

Prospect 

Mountain 

Quartzite

xXXXX/'X/^

Not 

exposed

Fish Springs and 

northern 

House Ranges, 

Utah

Hintze and Palmer 

(1976); Hintze and 

Robison (1975); 

Hintze and 

others (1988)

House Limestone

Notch Peak 

Formation

T Sneakover 

Ei Ls. Mbr.

c Corset Spring

|3 Johns Wash Ls. Mbr

o D candland Sh. 

,_ PA Member 6 

Big Horse 

Cr Ls. Mbr.

Lamb 

Dolomite

jg Ed Fish Springs 

a. Ed Mbr.

 §" Lower mbr.

Pierson Cove 

Formation

Pa Wheeler 

P g Shale

Gy Swasey Ls.

E Whirlwind Fm.

Dome Ls.

G Chisholm Fm.

p b Howell 

Limestone

E A 

u- Tatow Mbr. m

g Lower mbr.

CL

Prospect 

Mountain 

Quartzite

/^XN/NX'X/N

Not 

exposed

Deep Creek 

Mountains, 

Utah

McCollum and 

McCollum(1984); 

Hintze and 

others (1988); 

this report

Chokecherry 

Dolomite

Faulted out 

Ei Corset Spring Sh.

Johns Wash Ls.

p. Candland Fm.

Cr Ola Ss.

Lamb 

Dolomite

Ed Trippe 

Limestone

Pierson Cove 

Formation

Pa Wheeler 

P g Shale

Gy Swasey Ls.

E Whirlwind Fm.

Dome Ls.

Q Chisholm Sh.

Pb Howell 

Formation

c Busby 

S. Quartzite 

o> Member * 0? 

£ 0 cabin Sh. Mbr.

Prospect 

Mountain 

Quartzite

McCoy Creek 

Group 1

Of Misch and Hazzard (1962) as modified by Hose and Blake (1976).

Figure 5. Correlation of Cambrian formations in northern and 

central Great Basin. Reported occurrences of fossil zones are 

shown schematically by lettered symbol. The Middle-Upper 

Cambrian boundary in North America has traditionally been

8 Cambrian Stratigraphy of the Wendover Area, Utah and

placed between Bolaspidella and Cedaria zones (Lochman-Balk 

and Wilson, 1958; Robison, 1964). However, Daily and Jago 

(1975) noted that in reference to the standard of northwestern 

Europe, much of Cedaria zone of North America is Middle,

Nevada
Northern 

Goshute 

Mountains 

near 

Morgan Pass, 

Nevada

This report

Pogonip 

Group

Notch Peak

Formation

El

Dunderberg 

D Shale

PA

Cr Goshute Ls.

Cr Ola Sandstone

Lion Spring Ls.

C Shatter 

Formation

Decoy Ls.

d Morgan Pass 

B Formation

Clifside 

Limestone

/N/S/N/S/v

Not

exposed

Central 

Toano Range 

near 

Silver Zone 

Pass, 

Nevada

This report

Pogonip 

Group

Notch Peak

Formation

El

Dunderberg 

D Shale

o rr Oasis 

C Formation

c Shatter 

Formation

L

Decoy Ls.

Morgan Pass 

B Formation

Clifside 

Limestone

B

Pa

Toano 

Limestone

Killian 

Springs 

Formation

Prospect

Mountain

Quartzite

Not 

exposed

Central 

Pilot Range 

near 

Killian Springs, 

Utah

This report

Not 

exposed

Toano

Limestone

Killian 

Springs 

Formation

Prospect

Mountain

Quartzite

McCoy Creek 

Group 1

Central 

Silver Island 

Mountains 

near 

Tetzlaff Peak, 

Utah

This report

Not 

exposed

Pa 

Toano

Pg 

Limestone

Not

exposed

Killian 

Springs 

Formation

Prospect

Mountain

Quartzite

Not 

exposed

Northern 

Toano Range, 

Nevada

This report

Garden City 

Formation

Notch Peak

Formation

Corset Spring Sh.

Johns Wash Ls.

D Candland Fm.

Lamb Dol. and 

Big Horse Ls., 

undivided

Unnamed 

limestone

Not

exposed

Southern 

Pilot Range 

near 

Miners Canyon, 

Utah and Nevada

This report

Garden City 

Formation

Notch Peak

Formation

El Corset Spring Sh.

Johns Wash Ls.

D Candland Fm.

Big Horse 

Limestone

Not

exposed

Toano Limestone

Killian 

Springs 

Formation

Prospect

Mountain

Quartzite

McCoy Creek 

Group 1

Central 

Silver Island 

Mountains 

near 

Jenkins Peak, 

Utah

This report

Garden City 

Formation

S 

Notch Peak

Formation

T

El Corset Spring Sh.

Johns Wash Ls.

PA Candland Fm.

Big Horse 

Cr Limestone

Lamb 

Dolomite

Not

exposed

Northern 

Silver Island 

Mountains 

at 

Crater Island, 

Utah

Miller (1990)

Garden City 

Formation

Notch Peak

Formation

Corset Spring Sh.

Johns Wash Ls.

Candland Fm.

Big Horse 

Limestone

Lamb 

Dolomite

Trippe 

Limestone

Not

exposed

rather than Late, Cambrian in age. More recently, Robison 

(1984) has set Middle-Upper Cambrian boundary in western 

North America at top of Lejopyge laevigata zone, and thus includes much of Cedaria zone in Middle Cambrian. Pending

formal subdivision of Cambrian System, boundary is shown 

as questionable in this report. Strata between the Chokecherry 

Dolomite and Ola Sandstone were formerly assigned to the 

Hicks Formation (abandoned) of Nolan (1935).

Killian Springs Formation (New) 9
114°00' 113°45'

41° 

15'

41° 

00'

40° 

45'

:-t : " 

10 KILOMETERS

Mountainous areas

EXPLANATION

 mp

OGnp

 du

 o

 0!

CIs

 s

 d

Upper plate rocks 

(Ordovician and Cambrian)

Lower plate rocks (Ordovician, 

Cambrian, and Late 

Proterozoic)

Notch Peak Formation (Lower 

Ordovician and Upper Cambrian)

Dunderberg Shale (Upper Cambrian) 

Oasis Formation (Upper Cambrian) 

Goshute Limestone (Upper Cambrian) 

Ola Sandstone (Upper Cambrian)

Lion Spring Limestone (Upper 

Cambrian)

Shafter Formation (Upper and Middle 

Cambrian)

Decoy Limestone (Middle 

Cambrian)

 cl

 t

 ks

 Zpm

 cs

Cjw

 c

 bh

 l

 tr

Killian Springs 

(Middle and I

Morgan Pass Formation (Middle 

Cambrian)

Clifside Limestone (Middle 

Cambrian)

Toano Limestone (Middle 

Cambrian)

I 

Formation 

jower Cambrian)

Prospect Mountain Quartzite 

(Lower Cambrian and Late 

Proterozoic)

Corset Spring Shale (Upper 

Cambrian)

Johns Wash Limestone (Upper 

Cambrian)

Candland Formation (Upper 

Cambrian)

Big Horse Limestone (Upper 

Cambrian)

Lamb Dolomite (Upper Cambrian)

Tnppe Limestone (Middle 

Cambrian)

10 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
unit. The formational name is derived from Killian Springs, 

a natural spring located in the Patterson Pass TVa-minute 

quadrangle. This easily mappable unit, which was informally 

called the "phyllite of Killian Springs" by Miller (1983, p. 

203), forms dark-colored, broad benches between the underlying Prospect Mountain Quartzite and overlying Toano 

Limestone.

The type section of the Killian Springs Formation in 

the Pilot Range is a fairly uniform sequence of very dark, 

impure, fine-grained clastic rocks that conformably overlie 

the Prospect Mountain Quartzite. The clastic rocks contain 

progressively increasing calcareous interstitial material toward the top of the section. The dominant lithology is grayish-black phyllite and phyllitic siltstone. Graphitic arenite 

and subgraywacke locally are interbedded with siltstone near 

the base of the formation, and argillaceous lime mudstone 

and calcareous phyllite are relatively common in the upper 

one-third of the formation. Impressions of siliceous sponge 

spicules and articulated sponges are sporadically distributed 

in the phyllite and argillaceous lime mudstone within the 

upper half of the formation. The soil that forms on the 

Killian Springs is generally carbon rich and dark compared 

with adjacent formations, making the unit easily distinguishable on aerial photographs.

Fault-bounded phyllite units 20 to 60 m thick present 

south of the type section of the Killian Springs Formation 

within the Pilot Range (rocks that are here assigned to the 

Killian Springs Formation) were originally assigned to the 

Pioche Shale by O'Neill (1968) and to the Pioche Formation of Hintze and Robison (1975) by Miller and Lush 

(1981), but later they were designated by Miller (1984) as 

the phyllite of Killian Springs. Amphibolite-facies equivalents in a fault slice east of Pilot Peak consist of a distinctive black graphitic schist resting on the Prospect Mountain 

Quartzite, which was correlated with the lower grade phyllite by Miller and Lush (1981) and assigned to the phyllite 

of Killian Springs by Miller (1983, 1984). Structurally 

overlying this schist is a thick unit of brown schistose marble, 

with local interbeds of metamorphosed calcareous quartz 

sandstone. Distinctive units in this section consist of black 

graphitic marble and pelitic schist. The schistose marble 

unit appears to be a facies variation of the upper, calcareous 

part of the type section of the Killian Springs Formation; it 

is overlain by marble assigned in this report to the Toano 

Limestone.

Strata originally assigned by Pilger (1972) to the 

Pioche Shale in the Toano Range were reassigned by McCollum and McCollum (1984) to the phyllite of Killian

 ^ Figure 6. Distribution of Cambrian stratigraphic units in 

Wendover area, northeastern Nevada and northwestern Utah. 

Unit labeled Big Horse Limestone in the northern Toano Range 

is Lamb Dolomite and Big Horse Limestone, undivided (see 

text). See figure 1 for location.

Springs of Miller (1983). Click (1987) also adopted the 

phyllite of Killian Springs for her detailed geologic mapping in the northern Toano Range. The lithology and stratigraphic thickness of the Killian Springs Formation in the 

Toano Range are very similar to that of the type section of 

the unit in the Pilot Range.

On the north flank of Tetzlaff Peak in the central 

Silver Island Mountains, strata formerly mapped by Schaeffer (1960) as the (uppermost part of the) Prospect Mountain 

Quartzite, Pioche Shale, and Busby Quartzite are here assigned to the Killian Springs Formation. At this location, 

facies changes from those at the type section of the unit, 35 

km to the northwest, are evident, and approximately the 

upper one-third of the formation is not exposed locally. 

Three lithologically distinguishable, informally designated 

units comprise the Killian Springs here; they are, in ascending order, (1) a cliff-forming, 4-m-thick unit composed of 

interbedded quartzofeldspathic sandstone and dark phyllitic 

siltstone that weather into a stepped cliff profile; (2) a 90- 

m-thick, slope-forming unit composed of dark phyllitic siltstone and lime mudstone; and (3) a ridge-forming unit of 

friable, cavernous-weathering calcareous quartz sandstone 

with only its lowermost 35 m exposed. This upper unit may 

in part be correlative with the brown schistose marble unit 

of the Killian Springs occurring east of Pilot Peak.

Age. The age of the Killian Springs is not well 

constrained. The formation overlies the Prospect Mountain 

Quartzite, which regionally contains a late Early Cambrian 

fauna near its top in Nevada (Stewart, 1976). Sponge spicules from the upper half of the Killian Springs Formation 

are suggestive of Middle Cambrian Diagonella and Protospongia forms, according to J. Keith Rigby (written commun., 1983). Thus, the Killian Springs Formation is here 

provisionally regarded as Early and Middle Cambrian in 

age.

Regional Correlations. To the east and west of the 

Wendover region, the geographic distribution of dark, impure 

rocks has been masked either by the high degree of metamorphism and deformation or by inappropriate formational 

designations. Willden and Kistler (1979) used the name 

"Pioche Formation" for a 170-m-thick sequence of graphitic 

phyllite, hornfels, and marbleized limestone above the Prospect Mountain Quartzite at Rattlesnake Mountain in the 

central Ruby Mountains, Nevada (fig. 1). Black graphitic 

schist is present above prominent quartzite beds in the highly 

metamorphosed Cambrian section in the northern Ruby 

Mountains and adjacent East Humboldt Range in northern 

Nevada (Snoke and Lush, 1984), in the Pequop Mountains, 

and possibly also in the Albion Mountains of southern Idaho 

(Miller, 1983).

The metamorphic complex in the northern Ruby 

Mountains and adjacent East Humboldt Range contains a 

sillimanite zone (amphibolite-facies) Late Proterozoic to 

middle Paleozoic sequence. Howard (1971, p. 263) and 

Snoke (1980, p. 293) noted that a prominent graphitic calcKillian Springs Formation (New) 11
R7DE R19W

2 KILOMETERS

EXPLANATION

Suriicial deposits (Quaternary) 

Toano Limestone (Cambrian)

Killian Springs Formation 

(Cambrian)

Prospect Mountain Quartzite

(Cambrian and Late Proterozoic)

Unit G of McCoy Creek Group of 

Misch and Hazzard (1962) 

(Late Proterozoic)

Contact Dotted where 

concealed

Faults Dashed where 

approximate; dotted 

where concealed

 Low-angle Sawteeth 

on upper plate

 High-angle Bar and 

ball on downthrown 

side

Figure 7. Geologic map of part of Pilot Range, Utah and Nevada, showing location of type section of the 

Killian Springs Formation and reference section of the Toano Limestone. See figure 2 for location of map. 

Base from U.S. Geological Survey, 1:24,000-scale Patterson Pass 7/2-minute quadrangle, 1967, Nevada 

and Utah. Contour interval 20 ft. Geology generalized from D.M. Miller and others (1982).

12 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
silicate facies overlies the metamorphosed Prospect Mountain Quartzite throughout much of the area. Based on the 

stratigraphic position and graphitic component of these rocks, 

they appear to be a high-grade metamorphic equivalent of 

the Killian Springs Formation.

In the Albion Mountains of southern Idaho, black, 

graphitic phyllite and black staurolite-garnet schist are 

present structurally below the overturned Harrison Summit 

Quartzite of Armstrong (1968). Miller (1983) tentatively 

correlated the Harrison Summit Quartzite with the Prospect 

Mountain Quartzite and the black phyllite and schist facies 

strata with the herein-named Killian Springs Formation 

[equivalent to the phyllite of Killian Springs of Miller 

(1983)]. However, metamorphism and structural complexities including bedding-plane faults, which may have structurally interleaved Mississippian with Cambrian(?) phyllite 

and schist units (Miller, 1983), preclude a confident formational assignment for these rocks at this time.

A partial lithologic and temporal equivalent of the 

Killian Springs Formation is the Edgemont Formation of 

Decker (1962) in the Bull Run Mountains, 200 km west of 

the Pilot Range (fig. 1). The Edgemont is a highly folded 

and pervasively cleaved sequence of light-olive-gray to 

brownish-gray phyllitic mudstone and thinly interbedded 

quartz arenite in its basal part and minor silty lime mudstone beds in its uppermost 50 m (Clark, 1984). The 

Edgemont conformably overlies the Prospect Mountain 

Quartzite and is itself overlain by a thick-bedded, fenestral 

dolomite interval originally included in the Porter Peak 

Limestone of Decker (1962). Clark (1984, p. 49) estimated 

the maximum thickness of the Edgemont as approximately 

365 m but was unable to determine an internal stratigraphy 

for the unit owing to structural complications and poor exposures.

The uppermost 70 m of the Edgemont Formation in 

the Bull Run Mountains (fig. 1) contains a late Early Cambrian Bonnia-Olenellus Assemblage-zone fauna (Ehman, 

1985). A.R. Palmer (written commun., 1981) has identified 

Olenellus cf. 0. puertoblancoensis (Lochman), Olenellus cf. 

0. howelli ? (Meek), and Zacanthopsis sp. from a collection 

made by McCollum from the type section of the Edgemont 

in 1981. Palmer later identified Olenellus nevadensis 

(Walcott), Olenellus cf. 0. gilberti Meek, and Bonnia sp. 

from an additional collection several kilometers to the south 

reported by Clark (1984). Palmer concluded that all of these 

faunas are characteristic of uppermost Lower Cambrian strata 

within the Great Basin.

The Killian Springs Formation is distinguished from 

the Edgemont Formation by its greater lithologic heterogeneity, including graphitic phyllites, and by a higher proportion of coarse clastic rocks. The Killian Springs is overlain 

by thin-bedded and laminated, silty lime mudstone, whereas 

the Edgemont Formation is overlain by thick-bedded to 

massive, fenestral dolomite. The Edgemont contains a fairly 

diverse Early Cambrian benthic fauna, whereas the Killian

Springs is barren except for a few horizons containing likely 

Middle Cambrian sponge spicules.

Three hundred kilometers to the east in the Bannock 

Range near Pocatello, Idaho, the lower part of the Gibson 

Jack Formation (Crittenden and others, 1971) has some 

striking lithologic and faunal similarities with the Killian 

Springs Formation exposed at Tetzlaff Peak. Laminated, 

carbon-rich, black shale and argillaceous siltstone containing numerous spicules of Protospongia dominate the lowermost 100 m of the Gibson Jack Formation. Above this is a 

friable, calcareous quartz sandstone approximately 35 m 

thick, which is overlain by at least 300 m of siliceous shale. 

These mappable subunits were labeled members A, B, and 

C, respectively, by Trimble (1976, p. 27-28). Members A 

and B possibly represent an eastern tongue of the Killian 

Springs Formation, whereas the siliceous shale of member 

C is lithologically similar to facies found within the Ophir 

Shale and the Pioche Shale in the eastern and central Great 

Basin, respectively.

The Lower and Middle Cambrian Pioche Shale, 

which lies upon the Prospect Mountain Quartzite throughout the central Great Basin, is stratigraphically correlative 

with the Killian Springs Formation but is easily distinguished 

from the Killian Springs lithologically. The Pioche consists 

primarily of light-green to tan, siliceous and fissile shale; 

interbedded quartz arenite; and oolitic or algal, light-gray 

limestone commonly composed of trilobite hash. Lithologies attributed to the Pioche Shale are not exposed north of 

the Cherry Creek, Schell Creek, and Snake Ranges (fig. 1), 

and there are no exposed transitional facies near the 

Wendover area.

TOANO LIMESTONE (NEW)

The Toano Limestone is here named for an 850-mthick, slope-forming interval of silty lime mudstone and 

calcareous siltstone exposed about 4 km north of Silver 

Zone Pass in sec. 4, T. 35 N., R. 68 E., Silver Zone Pass 7/2- 

minute quadrangle, on the west side of the Toano Range, 

Elko County, Nevada (fig. 8); these rocks are designated as 

the type section of the unit. The formational name is derived 

from the Toano Range, where the only complete section of 

this formation is known. The Toano is equivalent to unit A 

of Pilger (1972) and the limestone of Toano of McCollum 

and McCollum (1984). The contacts of the Toano Limestone are gradational, and the formation occupies a stratigraphic position intermediate between the clastic rocks of 

the Killian Springs Formation below and the lighter colored, 

less silty carbonate rocks of the Clifside Limestone above.

The predominant lithology is a uniform-appearing, 

thin- to medium-bedded, silty limestone. The bedding is 

parallel except where disrupted by soft-sediment deformation. The color contrast between the grayish-orange silty 

layers, which weather to relief, and the medium-dark-gray

Toano Limestone (New) 13
4Q°5T

40°56'

2 KILOMETERS 

j

Qs

SOc

 mp

 cl

Cks

EXPLANATION 

Surficial deposits (Quaternary)

Granodiorite (Jurassic)

Cmp

Carbonate rocks (Silurian and 

Ordovician)

Morgan Pass Formation (Cambrian) 

Clifside Limestone (Cambrian) 

Toano Limestone (Cambrian)

Killian Springs Formation 

(Cambrian)

30

Prospect Mountain Quartzite

(Cambrian and Late Proterozoic)

Contact Contacts between members 

dashed

Faults Dashed where approximate; 

dotted where concealed

High-angle Bar and ball on 

down thrown side

Gravity-slide Hachures on 

upper plate

Strike and dip of bedding 

Fossil locality

14 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
lime mudstone presents the greatest variation within this 

formation.

The silty, laminated rocks of the Toano Limestone 

exhibit a large assortment of primary sedimentary features, 

owing in part to the lack of bioturbation. Although more 

than half of the formation is laminated, chaotic bedding and 

sedimentary folds due to slumping are common in the middle 

part of the unit (fig. 10). Imbricated clasts, truncation surfaces, and trough cross-stratification are also present (fig. 11).

In addition to its type section in the Toano Range, a 

complete section is present in the Pequop Mountains and

 ^ Figure 8. Geologic map of Toano Range north of Silver 

Zone Pass, Nevada, showing locations of type sections of the 

Toano Limestone and Clifside Limestone and reference section 

of the Killian Springs Formation. See figure 2 for location of 

map. Base from U.S. Geological Survey, 1:24,000-scale Silver 

Zone Pass 7>2-minute quadrangle, 1982, Nevada. Contour 

interval 40 ft. Geology generalized from Click (1987).

incomplete sections of the Toano Limestone are exposed in 

the Pilot Range (fig. 7) and central Silver Island Mountains 

(fig. 9). Approximately the lower one-third of the Toano 

Limestone is exposed above the type section of the Killian 

Springs Formation in the core of a large syncline in the 

central Pilot Range (D.M. Miller and others, 1982; Miller, 

1983). Several kilometers to the south in the Pilot Range, 

O'Neill (1968) mapped strata in Miners Canyon that we 

herein assign to the Toano Limestone. A light-colored 

schistose marble mapped by Miller and Lush (1981) east of 

Pilot Peak overlies metamorphosed strata of the Killian 

Springs Formation and is probably correlative with the Toano 

Limestone. The upper half of the Toano Limestone is the 

only unit exposed north of Tetzlaff Peak in the Silver Island 

Mountains, which Schaeffer (1960) tentatively mapped as a 

unit he called "Millard, Burrows?, and Burnt Canyon? 

Limestones, undifferentiated."

Age. The Toano Limestone contains sparse and 

coarsely silicified, open-shelf, cosmopolitan Middle Cambrian fossils at its type section. The youngest fauna, taken 

from the uppermost 10 m of the type section, contains a

113054' 113°53'

0.5 1 KILOMETER

EXPLANATION 

Surficial deposits (Quaternary)

Granite (Mesozoic?)

Carbonate rocks (Permian)

Carbonate rocks (Ordovician)

 ci Clifside Limestone (Cambrian)

Ct Toano Limestone (Cambrian)

Killian Springs Formation (Cambrian)

Prospect Mountain Quartzite (Cambrian 

and Late Proterozoic)

Contact

Faults Dotted where concealed

High-angle Bar and ball on 

downthrown side

Low- to moderate-angle 

Hachures on upper plate

Figure 9. Geologic map of Tetzlaff Peak area, central Silver Island Mountains, Utah, showing location of reference sections of 

the Killian Springs Formation and Toano Limestone. See figure 2 for location of map. Base from U.S. Geological Survey, 

1:24,000-scale Tetzlaff Peak 71/2-minute quadrangle, 1971, Utah. Contour interval 20 ft. Geology modified from D.M. Miller 

(1988, unpublished).

Toano Limestone (New) 15
species of Bolaspidella, identified by A.R. Palmer (written 

commun., 1983) and assigned to the late Middle Cambrian 

Bolaspidella Assemblage-zone of Robison (1976, p. 102). 

R.A. Robison (written commun., 1982) identified numerous 

specimens of Ptychagnostus atavus (Tullberg) from 650 m 

above the base of the formation, both in the type section 

and in the Silver Island Mountains. He also collected 

Tonkinella and several questionable specimens of Ptychagnostus between 80 m and 90 m below the P. atavus fauna in 

the central Silver Island Mountains, indicating the presence 

of the Ptychagnostus gibbus Interval-zone of Robison 

(1984). A possible specimen of the trilobite Elrathia sp. 

identified by A.R. Palmer (written commun., 1983) was 

collected from a fault block of Toano Limestone on the 

east side of the Pilot Range. In addition, poorly preserved 

agnostoid and ptychopariid trilobites have been collected

300 m above the base of the type section of the Toano 

Limestone, and these could be as old as the early Middle 

Cambrian Peronopsis bonnerensis Assemblage-zone of 

Robison (1976, p. 103). The lower one-third of the Toano 

Limestone in the Toano Range appears to be barren. Based 

on the faunal evidence and the presumed Middle Cambrian 

age of the upper part of the underlying Killian Springs Formation, the Toano Limestone is considered to be Middle 

Cambrian in age.

Regional Correlations. At present, the Toano 

Limestone is recognized outside of the Wendover area only 

in the Pequop Mountains. In the Tennessee Mountains (fig. 

1), 160 km to the northwest, the Tennessee Mountain Formation of Bushnell (1967) overlies an unnamed phyllitic 

siltstone unit above the Prospect Mountain Quartzite. Although lithologically similar to the Toano Limestone, the

Figure 10. Soft-sediment slumps in the Toano 

Limestone. A, Chaotically arranged clasts; quarter 

shown for scale. 6, Sharp upper contact of slump 

with overlying laminated lime mudstone; lens cap 

5.3 cm wide shown for scale. C, Drag fold at base 

of a slump; quarter shown for scale.

B

16 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Tennessee Mountain Formation may include rocks as young 

as Ordovician. In the Bull Run Mountains, a unit composed 

of thick-bedded to massive fenestral dolomite approximately 

1,160 m thick (Clark, 1984) occupies the stratigraphic position of the Toano Limestone above the Edgemont Formation of Decker (1962). The Aura Formation of Decker (1962) 

and the Van Duzer Limestone of Decker (1962), which 

overlie the dolomite, are lithologically similar to the Toano 

but are Late Cambrian and Early Ordovician in their overall 

age, according to Ehman (1985). At Rattlesnake Peak in the 

central Ruby Mountains, Willden and Kistler (1979) recognized an unnamed, dark-gray silty limestone unit lithologically similar to the Toano Limestone above their Pioche 

Formation.

Cambrian and Ordovician carbonate rocks exposed 

in the folded, high-grade metamorphic complex of the 

northern Ruby Mountains and adjacent East Humboldt Range 

are difficult to subdivide into units correlative with less 

metamorphosed sections. However, the thin-bedded nature 

of the calc-silicate rocks and marble overlying the graphitic 

schist of the metamorphosed Killian Springs(?) Formation 

in this area is consistent with a protolith of organic silty 

lime mudstone typical of the Toano Limestone.

CLIFSIDE LIMESTONE (NEW)

The Clifside Limestone is here named for an approximately 650-m-thick sequence of alternating gray limestone and brown silty limestone exposed on the crest and 

east slope of the Toano Range in sec. 3 and 4, T. 35 N., R. 

68 E., Silver Zone Pass 754-minute quadrangle, Nevada, 

about 2 km north of Clifside railroad siding in the Silver 

Zone Pass (1971) 7/4-minute quadrangle; these rocks are 

designated as the type section of the unit (fig. 8). It consists 

of most of unit B of Pilger (1972), the limestone of Clifside 

of McCollum and McCollum (1984), and units A, B, and C 

of the limestone of Clifside of Click (1987). The Clifside 

Limestone is exposed only within the Toano Range, Pequop Mountains, and northern Goshute Mountains. The 

stratigraphic interval that would be occupied by the Clifside 

Limestone is apparently not exposed in the Pilot Range or 

Silver Island Mountains.

The lower contact of the medium- to light-gray Clifside Limestone is placed at a prominent color and textural 

change above the darker gray, more laminated silty carbonate rocks of the Toano Limestone. The upper contact of the 

type section of the Clifside is a fault contact with the overlying Clifside Limestone and Morgan Pass Formation (fig. 

8). However, a sharp depositional contact separates the 

Clifside from the overlying slope-forming, silty limestone 

and calcareous siltstone of the Morgan Pass Formation south 

of Silver Zone Pass and in the Morgan Pass section of the 

northern Goshute Mountains.

Click (1987) divided her limestone of Clifside into 

five informal units, units A through E. Her units D and E 

are structurally separated from the remainder of the Clifside 

unit, and their strata are tentatively assigned herein variously to the Morgan Pass, Shatter, and Oasis Formations. 

Units A, B, and C of the limestone of Clifside of Glick 

(1987) represent a convenient tripartite division locally 

within the type section of the Clifside Limestone and are 

here recognized as the lower limestone, silty limestone and 

shale, and upper limestone members, respectively, of the 

Clifside Limestone.

The lower limestone member (equivalent to Click's 

unit A) is characterized by alternating bands of light-gray 

oolitic limestone and light- to moderate-brown silty limestone. The repetitious occurrence of light-gray oolitic grainstone interbedded with medium-gray wackestone (zebrastriped pattern), alternating with layers of moderate-brown

B

Figure 11. Soft-sediment features of the Toano Limestone. A, 

Imbricated clasts near top of a slump. Note deformation of 

base of clast on left. 6, Deformed trough cross-stratification.

Clifside Limestone (New) 17
siltstone with medium-gray wackestone interbeds (tigerstriped pattern), is the most distinguishing lithologic characteristic of this member. The member is 265 m thick in the 

type section of the Clifside Limestone.

The silty limestone and shale member (equivalent to 

Click's unit B) is composed of basal black shale and oolitic 

and algal limestone, overlain by yellowish-orange silty 

limestone. The lower one-third of this member weathers 

recessively and forms a prominent saddle across ridges that 

developed on the dip slope of the type section of the Clifside Limestone. This member ranges in thickness from 155 

to 175 m in the Clifside section north of Silver Zone Pass, 

to 205 m just south of the pass.

The upper limestone member [equivalent to Click's 

unit C in the northern Toano Range and unit H of Day and 

others (1987) in the southern Toano and northern Goshute 

Mountains] is a medium-dark-gray limestone with thin, 

laminated to undulose silty layers. Fenestral fabric is present in the lower one-third of the Clifside type section, and 

cryptalgalaminites and oncolites are common throughout 

the member south of Silver Zone Pass. An incomplete section of 210 m is exposed in the type section of the Clifside 

Limestone but thins to only 100 m in a dolomitic section 

south of Silver Zone Pass.

The Clifside Limestone is locally dolomitized, extensively recrystallized, and bleached to a cream color near 

the Silver Zone Pass pluton, Tremolite and aligned white 

mica, accompanied by the loss of primary sedimentary features, are characteristic of the Clifside there. The upper 

limestone member of the Clifside forms the lowest exposures of the Cambrian section in Morgan Canyon.

Age. The only fossils recovered from the Clifside 

Limestone are a few marjumid trilobites and numerous inarticulate linguloid brachiopods found within its silty limestone and shale member. However, Bolaspidella is present in 

the uppermost beds of the underlying Toano Limestone and 

also in the basal part of the overlying Morgan Pass Formation. Thus, the Clifside is entirely within the Bolaspidella 

Assemblage-zone in the upper Middle Cambrian. Therefore, the Clifside Limestone is considered to be Middle 

Cambrian in age.

Regional Correlations. The Clifside Limestone 

appears to be partially age equivalent to the interbedded 

shale and silty limestone of the Marjum Formation in the 

west-central House Range; to the silty to pure limestone in 

the middle part of the Raiff Limestone of Young (1960) in 

the Cherry Creek, northern Egan, and northern Schell Creek 

Ranges; and to the thin- to medium-bedded limestone of 

the Pierson Cove Formation and the lower part of the overlying Trippe Limestone in the Deep Creek Mountains and 

Fish Springs Range, all far south of the Wendover region. 

To the west, the Clifside may be partially age equivalent to 

the hemipelagic carbonate rocks and interbedded phyllitic 

shales of the Tennessee Mountain Formation of Bushnell 

(1967) in the Tennessee Mountains and to the Aura Formation of Decker (1962), as described by Ehman (1985), in 

the Bull Run Mountains. The Rattlesnake Peak section of 

Willden and Kistler (1979) in the central Ruby Mountains 

contains an unnamed limestone unit that is approximately 

age equivalent (latest Middle Cambrian) to the (combined) 

Clifside Limestone and overlying Morgan Pass Formation. 

Whether or not these unit names can eventually be applied 

to these strata in the Ruby Mountains will have to await 

further investigation.

MORGAN PASS FORMATION (NEW)

The Morgan Pass Formation is here named for a 

225-m-thick sequence of slope-forming shale and silty 

limestone exposed 1 km west of Morgan Pass in sec. 21, T. 

32 N., R. 68 E., Morgan Pass 7/2-minute quadrangle, at the 

northern terminus of the Goshute Mountains (figs. 12,13). 

It consists of all the strata designated as units F and G by 

Day and others (1987). The formational name is derived 

from Morgan Pass. The basal contact of the unit is sharp 

and is placed at the base of the lowest shale or silty limestone above the massive, ridge-forming Clifside Limestone, 

whereas its upper contact is gradational and is placed at the 

top of the slope below the cliff-forming Decoy Limestone. 

The Morgan Pass Formation is present south of Silver Zone 

Pass in the central Toano Range (fig. 14) and in the Pequop 

Mountains but is not exposed to the east in the Pilot Range 

or Silver Island Mountains.

The Morgan Pass Formation is largely covered, except for two prominent limestone ledges between 40 and 65 

m above its base. Small grayish-orange to yellowish-brown 

chips of calcareous siltstone, silty limestone, and shale float 

cover the steep slopes. Thin, parallel-bedded, grayish-orange 

calcareous siltstone, alternating with medium-dark-gray 

limestone, is present in limited and widely scattered exposures throughout the formation. The uppermost 19 m of the 

formation is well exposed in its type section, where oolitic 

grainstones, rip-up clasts, and stromatolitic layers (fig. 15) 

are present within the calcareous siltstone and limestone 

sequence.

South of Silver Zone Pass, oolitic and oncolitic 

limestone beds become more common throughout the Morgan Pass Formation as the silt content decreases. The formation also thins substantially to 125 m there.

Age. Faunas within the Morgan Pass Formation 

are restricted to the upper half of the Middle Cambrian. A 

Middle Cambrian Bolaspidella Assemblage-zone fauna is 

present in the basal beds of the Morgan Pass Formation in 

the central Toano Range and in both of the prominent ledgy 

limestone layers between 40 and 65 m above the base of 

the unit's type section. An Eldoradia Assemblage-zone 

fauna is present in the uppermost 20 m in the type section. 

Thus, the age of the Morgan Pass Formation is considered 

to be Middle Cambrian.

18 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Regional Correlations. The Morgan Pass Formation, although lithologically quite different, appears to be 

correlative with the Fish Springs Member of the Trippe 

Limestone, exposed in several mountain ranges in westcentral Utah. The Trippe Limestone was named by Nolan 

(1935) for exposures in the Deep Creek Mountains in Utah, 

just to the south of the study area, and consists of a thinbedded limestone and dolomite sequence approximately 230 

m thick. Hintze (1974) and Hintze and Robison (1975) reported an Eldoradia Assemblage-zone fauna from the upper half of the Trippe Limestone regionally.

DECOY LIMESTONE (NEW)

The Decoy Limestone is here named for a 60-mthick, massive, light-gray limestone exposed 1 km west of 

Morgan Pass in sec. 21, T. 32 N., R. 68 E., Morgan Pass

7/2-minute quadrangle, at the northern terminus of the Goshute Mountains (figs. 12, 13); these rocks are also designated as the type section of the unit. The Decoy is equivalent to unit E of Day and others (1987). The formational 

name is derived from Decoy, a site along the Northern 

Nevada Railroad, 17 km to the west [see Decoy 7%-minute 

(1971) quadrangle].

The Decoy Limestone is a very distinctive unit that 

generally forms a bold gray band of limestone, commonly 

recrystallized, between darker, well-bedded slope-forming 

formations. The lower contact of the Decoy Limestone is 

placed at the top of the thin-bedded calcareous siltstone and 

interbedded dark-gray limestone of the Morgan Pass Formation. The upper contact is placed at the top of the highest 

massive limestone below the recessive, thin-bedded Shafter 

Formation.

The Decoy Limestone is also present south of Silver 

Zone Pass in the central Toano Range (fig. 14) and in the

114°20'

Figure 12. Geologic map of the Morgan Pass area, northern 

Goshute Mountains and southern Toano Range, Nevada, 

showing locations of type sections of the Morgan Pass Formation, Decoy Limestone, Shafter Formation, Goshute Limestone, 

Ola Sandstone, and Lion Spring Limestone, and reference

114° 17'30" EXPLANATION

Qs | Surficial deposits (Quaternary)

Qgc | Garden City Formation (Ordovician)

O np| Notch Peak Formation (Ordovician and 

Cambrian)

 duj Dunderberg Shale (Cambrian) 

 g.;| Goshute Limestone (Cambrian) 

Ola Sandstone (Cambrian) 

Lion Spring Limestone (Cambrian) 

Shafter Formation (Cambrian) 

Decoy Limestone (Cambrian) 

Cmp I Morgan Pass Formation (Cambrian) 

 cl | Clifside Limestone (Cambrian)

Contact

Low-angle fault Sawteeth on hanging 

wall

High-angle fault Bar and ball on 

downthrown side

Sections

Type section Morgan Pass Formation

Type section Decoy Limestone 

Type section Shafter Formation

Type section Lion Spring Limestone, 

Ola Sandstone, and Goshute 

Limestone

Reference section Dunderberg Shale

Partial reference section Notch Peak 

Formation

sections for the Dunderberg Shale and Notch Peak Formation. See figure 2 for location of map. Base from U.S. Geological Survey, 1:24,000-scale Morgan Pass and Lion Spring 

7/2-nninute quadrangles, 1972, Nevada. Contour interval 40 

ft. Geologic contacts generalized from Day and others (1987).

Decoy Limestone (New) 19
Figure 13. Morgan Pass section, Goshute Mountains. Ridge on left contains type and 

reference sections for several formations. In sequence upward from base, Morgan Pass 

Formation underlies tree-covered slope, Decoy Limestone is lowest prominent white band 

of cliffs, Shafter Formation underlies next slope, Lion Spring Limestone is knob-forming 

limestone unit near skyline, and Ola Sandstone lies just below white, massive, upper cliffs 

of the Goshute Limestone. Dunderberg Shale underlies uppermost grassy slope on hill at 

right side of photograph, above cliffs of Goshute Limestone.

Pequop Mountains. The Decoy is highly recrystallized and 

dolomitic, but retains a thickness of 60 m, except where 

locally removed by faulting. The Decoy Limestone is not 

exposed in the Pilot Range or Silver Island Mountains to 

the east.

Age. No faunas have been recovered from the Decoy Limestone in the study area. This may be due in part to 

extensive recrystallization and the massive texture of the unit. 

However, the Decoy Limestone is bracketed by late Middle 

Cambrian faunas in adjacent formations. Thus, the age of 

the Decoy Limestone is considered to be Middle Cambrian.

Regional Correlations. The Decoy Limestone 

comprises the northern exposures of a prominent and widespread limestone facies in eastern Nevada. Regionally, the 

light- to medium-gray limestone forms a prominent ridge or 

small cliff between slope-forming, shalier facies. Its 

relatively pure carbonate strata range in thickness from 5 to 

75 m regionally and are overlain by shaley strata containing 

trilobites of the Lejopyge laevigata Interval-zone of Robison 

(1984).

The Decoy Limestone is correlative with the (middle) 

limestone member of the Lincoln Peak Formation mapped 

by Drewes (1967) in the northern Schell Creek Range. The 

regional distribution of this limestone unit was depicted by 

Palmer (1971, p. 67), and it is present in the type section of 

the Lincoln Peak in the Snake Range (A.R. Palmer, written

commun., 1989), in the Lincoln Peak Formation at the junction of the White Pine Mountains and Grant Range to the 

south (R.A. Robison, written commun., 1984), within the 

upper Marjum Formation in the House Range, and within 

an unnamed limestone unit of Willden and Kistler (1979, p. 

229-230). The Decoy is also correlative with (basal) member A of the Emigrant Springs Limestone of Kellogg (1963) 

in the southern Schell Creek Range.

SHAFTER FORMATION (NEW)

The Shafter Formation is here named for a 200-mthick, thin-bedded, dark-gray silty limestone exposed 1 km 

west of Morgan Pass in sec. 21, T. 32 N., R. 68 E., Morgan

Figure 14. Geologic map of Toano Range south of^- 

Silver Zone Pass, Nevada, showing location of type section of 

the Oasis Formation and reference sections of the Clifside 

Limestone, Morgan Pass Formation, Decoy Limestone, Shafter 

Formation, Dunderberg Shale, and Notch Peak Formation. 

See figure 2 for location of map. Base from U.S. Geological 

Survey, 1 :24,000-scale Silver Zone Pass 7>2-minute quadrangle, 1982, and West Morris Basin 71/2-minute quadrangle, 

1971, Nevada. Contour interval 40 ft. Generalized geology 

from unpublished mapping by D.M. Miller.

20 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
114°1730"

2 KILOMETERS

EXPLANATION

Qs

Ts

PIPI

Surficial deposits (Quaternary) 

Sedimentary rocks (Tertiary) 

Granodiorite (Jurassic)

Limestone (Permian and 

Pennsylvanian)

Garden City Formation 

(Ordovician)

Notch Peak Formation

(Ordovician and Cambrian)

Dunderberg Shale (Cambrian) 

Oasis Formation (Cambrian) 

Shafter Formation (Cambrian) 

Decoy Limestone (Cambrian)

60

Morgan Pass Formation 

(Cambrian)

Clifside Limestone (Cambrian) 

Toano Limestone (Cambrian)

Contact

Faults Dashed where

approximate; dotted where 

concealed

 High-angle Bar and ball on 

downthrown side

 Gravity-slide Hachures on 

upper plate

Strike and dip of bedding

Shafter Formation (New) 21
Pass 714-minute quadrangle, at the northern terminus of the 

Goshute Mountains (fig. 12); these rocks are also designated as the type section of the unit. The Shatter is equivalent to unit D of Day and others (1987). The formational 

name is derived from Shafter, a site along the Union Pacific 

Railroad, 25 km to the northwest [see Shafter 7/2-minute 

(1971) quadrangle]. The Shafter Formation is also present 

south of Silver Zone Pass in the Toano Range (fig. 14) and 

in the Pequop Mountains, but the unit is not exposed in the 

Pilot Range or Silver Island Mountains.

The lower half of the Shafter Formation forms a 

prominent recessive and largely covered interval. The thinto medium-bedded, dark-gray, aphanitic limestone erodes 

readily along parallel silty laminations, forming blocky 

limestone talus on south-facing slopes. A much deeper soil 

development is present in the higher elevations on northfacing slopes, including the type section, which supports 

dense stands of conifers and other vegetation.

The upper half of the Shafter Formation is composed of medium-gray limestone and grayish-orange silty 

limestone to calcareous siltstone. In appearance, this lithology closely resembles that of the Morgan Pass Formation, 

but the Shafter can be distinguished from the Morgan Pass 

by the former's more undulose bedding and more irregular 

weathering pattern. The upper half of the Shafter forms 

steeper slopes and is better exposed than the lower half 

of the unit. In the Morgan Pass area, the upper contact 

of the Shafter Formation is relatively sharp and is placed 

at the boundary separating the formation's thin, interbedded limestones and calcareous siltstones below from the 

massive, cliff-forming beds of the Lion Spring Limestone 

above.

Age. The lower half of the Shafter Formation contains polymeroid trilobites and inarticulate brachiopods of 

the upper Bolaspidella and Cedaria Assemblage-zones. 

Baltagnostus and Clavagnostus, elements of the uppermost 

Middle Cambrian Lejopyge laevigata Interval-zone of Robison (1984), are also present in the Shafter Formation. 

Robison (1984, p. 8) reassigned much of the North American Cedaria Assemblage-zone to the Middle Cambrian. 

Thus, the Shafter Formation is mostly, if not entirely, Middle 

Cambrian in age.

Regional Correlations. The Lamb Dolomite, named 

by Nolan (1935) for exposures in the Deep Creek Mountains 

of Utah, is a partial temporal equivalent of the Shafter Formation. The Lamb Dolomite is a widespread unit, present 

not only in the study area, but also in several mountain 

ranges to the south. Throughout its geographic extent, the 

Lamb Dolomite consists of massive, light-gray, oolitic and 

oncolitic dolomite, which contrasts sharply with the thinbedded limestones and calcareous siltstones of the Shafter 

Formation.

The approximately 400-m-thick Weeks Limestone, 

exposed only in the west-central House Range (Hintze and 

Robison, 1975), is lithologically similar to and temporally 

equivalent with the Shafter Formation. The lower half of 

both formations is composed of thin, parallel-bedded, micritic limestone. However, the upper Weeks contains bioFigure 15. Stromatolitic limestone interval near the base of Morgan Pass Formation in 

Morgan Pass, northern Goshute Mountains.

22 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
clastic and oolitic limestones, which are not present in the 

Shafter. The Weeks Limestone was deposited in a localized 

depocenter within the House Range embayment (Rees, 

1986), which may account for it being twice the thickness 

of the Shafter. In addition, the Shafter and Weeks are separated geographically from one another by the largely temporally equivalent Lamb Dolomite, exposed in the intervening mountain ranges, such as the Fish Springs Range, Deep 

Creek Mountains, and Silver Island Mountains.

In eastern Nevada, the lower part of the "upper shale 

member" (see Drewes, 1967, p. 12) of the Lincoln Peak 

Formation is correlative with the Shafter Formation. In the 

southern Schell Creek Range, the lower half of member B 

of the Emigrant Springs Limestone of Kellogg (1963) also 

appears to correlate with the Shafter. The "unnamed hornfels formation" of Willden and Kistler (1979) in the central 

Ruby Mountains is roughly correlative with the Shafter, 

although an exact correlation is hampered by lack of faunal 

control in this and other Cambrian sections to the west of 

the Wendover region.

LION SPRING LIMESTONE (NEW)

The Lion Spring Limestone is here named for an 

85-m-thick limestone to silty limestone sequence that forms 

the basal unit of a tripartite cliff-forming section exposed 1 

km west of Morgan Pass in sec. 21, T. 32 N., R. 68 E., 

Morgan Pass 71/2-minute quadrangle, at the junction of the 

Toano Range and Goshute Mountains (figs. 12,13); these 

rocks are designated as the type section of the unit. The 

formation is equivalent to unit C of Day and others (1987), 

a mappable unit exposed over several square kilometers 

and believed to underlie a much greater area. The Lion 

Spring Limestone is a cliff former that has not been observed elsewhere in the northern Great Basin. The formational name is derived from Lion Spring, located approximately 6 km south of the type section in the Lion Spring 

71/2-minute quadrangle in the northern Goshute Mountains. 

The basal contact of the formation is relatively sharp and is 

placed at the base of a relatively pure cliff-forming limestone interval above the calcareous siltstones and silty limestones of the underlying Shafter Formation. The upper contact is somewhat gradational and is placed at the base of a 

distinct color and lithologic change of the overlying yellowish-orange to brick-red Ola Sandstone.

Texturally, the Lion Spring Limestone is generally 

massive and forms a bold, light- to medium-gray cliff. The 

medium- to thick-bedded carbonate unit contains some thin 

silty interbeds, silty mottles, and fenestral fabric. Oncolitic 

and oolitic interbeds are also present.

Age. Trilobite hash from the middle part of the 

Lion Spring Limestone contains a Crepicephalus Assemblage-zone fauna. The underlying Shafter Formation contains a Cedaria Assemblage-zone fauna in its upper beds,

and thus the Lion Spring Limestone is considered to be 

early Late Cambrian in age.

OLA SANDSTONE (NEW)

The Ola Sandstone is here named for a 60-m-thick 

sequence of ridge- to cliff-forming quartz sandstone, calcareous siltstone, and silty limestone exposed 1 km west of 

Morgan Pass in sec. 21, T. 32 N., R. 68 E., Morgan Pass 

7A-minute quadrangle; these rocks are designated as the 

type section of the unit. The Ola is equivalent to unit B of 

Day and others (1987) exposed in the Goshute Mountains 

(figs. 12,13). The formational name is derived from Ola, a 

site along the Western Pacific Railroad, 15 km to the northeast [see Ola 71/2-minute (1972) quadrangle]. In the Deep 

Creek Mountains, the uppermost 50 m of the Lamb Dolomite, which consists of a very distinctive sandstone lithology, is here reassigned to the Ola Sandstone.

The Ola Sandstone consists of reddish-orange 

medium-bedded sandstone, calcareous siltstone, and silty to 

oolitic limestone that is sandwiched between two massive 

cliff-forming carbonate units. It represents an important but 

rather limited lithofacies in which coarse- to fine-grained 

quartz sand and silt were deposited. Its yellowish-orange to 

brick-red color and quartz sand make it one of the 

most distinctive Upper Cambrian formations in the Great 

Basin.

Age. Tricrepicephalus is abundant in trilobite 

packstone near the top of the type section for the Ola Sandstone in the Morgan Pass section in the Goshute Mountains. 

In the Deep Creek Mountains, Bick (1966, p. 35) reported a 

Crepicephalus Assemblage-zone fauna from the uppermost 

part of the Lamb Dolomite, which is reassigned to the Ola 

Sandstone in this report. In the northern Goshute Mountains, the underlying Lion Spring Limestone and the overlying Goshute Limestone both contain Crepicephalus Assemblage-zone faunas. Thus, the Ola Sandstone is considered to be entirely Late Cambrian in age.

GOSHUTE LIMESTONE (NEW)

The Goshute Limestone is here named for a 65-mthick, cliff-forming, light- to medium-gray limestone sequence exposed 1 km west of Morgan Pass in sec. 21, T. 32 

N., R. 68 E., Morgan Pass 7/2-minute quadrangle; these rocks 

are designated as the type section of the unit (figs. 12, 13). 

The formational name is derived from the Goshute Mountains, where the unit is exposed. The Goshute is equivalent 

to unit A of Day and others (1987); its thickness is as great 

as 200 m.

Texturally, the Goshute Limestone is medium-bedded to massive, and it forms inaccessible cliffs throughout 

much of its outcrop area. Its relatively pure limestone is

Goshute Limestone (New) 23
recrystallized, giving a uniform light- to medium-gray color. 

Thin silty layers, silty mottles, and several oncolitic beds 

are present. Basal and upper contacts of the formation are 

relatively sharp. The lower contact is placed at the top of 

the calcareous siltstone in the underlying Ola Sandstone; 

the upper contact is placed at the base of the overlying 

recessive, thin-bedded Dunderberg Shale in the northern 

Goshute Mountains and at the base of the Candland Formation in the Deep Creek Mountains.

Age. A Crepicephalus Assemblage-zone fauna is 

present 10 m below the top of the Goshute Limestone. 

Therefore, the Goshute Limestone is considered to be entirely early Late Cambrian in age.

Regional Correlations for the Lion Spring Limestone, 

Ola Sandstone, and Goshute Limestone. The Lion Spring 

Limestone, Ola Sandstone, and Goshute Limestone are 

temporally equivalent to the Oasis Formation and the Big 

Horse Limestone in the study area. They are also temporally equivalent to the upper part of the Raiff Limestone of 

Young (1960) in the Cherry Creek, northern Egan, and 

northern Schell Creek Ranges in eastern Nevada. In the 

Deep Creek Mountains of western Utah, the upper part of 

the Lamb Dolomite (as stratigraphically restricted in this 

report) is the age equivalent of the Lion Spring Limestone 

mapped elsewhere. The Ola Sandstone is present in the 

Deep Creek Mountains and Dugway Range above the Lamb 

Dolomite (emended). In the Deep Creek Mountains, the 

Goshute Limestone is equivalent to an unnamed dolomite 

in the lower part of the herein-abandoned Hicks Formation.

OASIS FORMATION (NEW)

The Oasis Formation is here named for a 145-mthick sequence of light-gray recrystallized limestone, bluish-gray dolomite, and calcareous siltstone exposed in the 

central Toano Range. The type section is located southeast 

of Silver Zone Pass in sec. 33, T. 35 N., R. 68 E., West 

Morris Basin 7/2-minute quadrangle (fig. 14). The formational name is derived from a small village on Interstate 80 

[see Cobre T/^-minute (1967) quadrangle], approximately 30 

km to the northwest of the type section. Although the Oasis Formation has a limited outcrop area, it is a very distinctive unit because of its uniform light-gray color, coarsely 

crystalline texture, and slope-forming outcrop pattern. The 

Oasis Formation crops out in the Pequop Mountians and 

Wood Hills but is not described elsewhere in Utah and 

Nevada.

The basal and upper contacts of the formation are 

relatively sharp and are placed at the top of the calcareous 

siltstone in the underlying Shatter Formation and the base 

of the overlying recessive, thin-bedded Dunderberg Shale, 

respectively. Much of the Oasis Formation is composed of 

mottled lime mudstone, trilobite packstone, oolitic grainstone, cryptalgalaminites, and fenestral lime mudstone. A 

10-m-thick, light-brown calcareous siltstone is present 60 

m below the top, and thin, light-gray dolomitic silty layers 

are common throughout.

Age. Early Late Cambrian faunas assigned to the 

upper Cedaria or lower Crepicephalus Assemblage-zones are

Figure 16. Upper Cambrian section, central Silver Island Mountains, Utah, near Jenkins Peak. 

Prominent white band is the Johns Wash Limestone.

24 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
present between 7 and 10 m above the base of the Oasis 

Formation at its type section in the Toano Range. The basal 

beds of the overlying Dunderberg Shale contains a Dicanthopyge Assemblage-zone fauna. Thus, the Oasis Formation is considered to be early Late Cambrian in age.

Regional Correlations. The Oasis Formation is 

temporally equivalent to the Big Horse Limestone Member 

and lower beds (pre-Aphelaspis Assemblage-zone) of the 

Candland Shale Member of the Orr Formation in west-central Utah. To the north in the Deep Creek Mountains, the 

Oasis is equivalent to the upper part of the Lamb Dolomite 

(restricted), the overlying Ola Sandstone, and the unnamed 

dolomite that was previously included as the base of the 

herein-abandoned Hicks Formation. In eastern Nevada, the 

middle part of the "upper shale member" (see Drewes, 1967, 

p. 12) of the Lincoln Peak Formation contains a 

Crepicephalus Assemblage-zone fauna (Drewes and Palmer, 

1957). The lack of faunal control and formational descriptions precludes any regional correlations west of the 

Wendover region.

DUNDERBERG SHALE

The Dunderberg Shale, named by Walcott (1908b) 

in the Eureka district, Nevada, and revised there by Nolan 

and others (1956), crops out widely in east-central Nevada. 

As indicated in fig. 5, the Dunderberg Shale includes five 

faunal zones, ranging from the upper Aphelaspis Assemblage-zone into the Elvinia Assemblage-zone (Palmer, 1960, 

1965). The Dunderberg ranges in thickness from 81 m in its 

type section to 190 m in the Cherry Creek Range (Palmer, 

1965).

The Dunderberg Shale is present south of Silver Zone 

Pass in the Toano Range, in the Pequop Mountains, in the 

Wood Hills, and in the Morgan Pass section in the northern 

Goshute Mountains (figs. 12-14). Regionally, it is about 

150 m thick and has thin-bedded, dark-gray to black shale 

and argillaceous limestone in its lower half and pale-olive 

to tan shale and medium-bedded crinoidal limestone in its 

upper half. Faunas collected during this study and identified by A.R. Palmer (written commun., 1984, 1986, 1987)

113°50'

40° 

52' 

30"

Reference section 

Big Hor!$fc Is, 

Candland Fm

0.5 

I

1 KILOMETER

EXPLANATION

Surficial deposits 

(Quaternary)

Garden City Formation 

(Ordovician)

Notch Peak Formation 

(Ordovician and 

Cambrian)

Corset Spring Shale, Johns 

Wash Limestone, 

Candland Formation, 

and Big Horse 

Limestone, undivided 

(Cambrian)

Lamb Dolomite (Cambrian) 

Contact

High-angle fault Bar and 

ball on down thrown side

Figure 17. Geologic map of Jenkins Peak area, central Silver Graham Peak 7/2-minute quadrangle, 1971, Utah. Contour

Island Mountains, Utah, showing location of reference sections 

of the Big Horse Limestone, Candland Formation, Johns Wash 

Limestone, and Corset Spring Shale. See figure 2 for location 

of map. Base from U.S. Geological Survey, 1 :24,000-scale

interval 40 ft. Geology modified from Schaeffer (1960); because Schaeffer did not break these units out, central part of 

section is undivided.

Dunderberg Shale 25
from the Dunderberg Shale in the Silver Zone Pass and 

Morgan Pass sections represent the Dicanthopyge to Elvinia 

Assemblage-zones.

The Dunderberg Shale in the Toano Range south of 

Silver Zone Pass (fig. 14) is temporally equivalent to the 

(combined) Candland Formation, Johns Wash Limestone, 

and Corset Spring Shale in the Silver Island Mountains, the 

southern Pilot Range, and the northern Toano Range. This 

represents the most striking facies change between the Upper Cambrian sections exposed below and above the Pilot 

Peak detachment. Absent in the lower-plate section is the 

prominent "white band" lithology (equivalent to recrystallized white limestone) mentioned by Schaeffer (1960, p. 

32) in the central Silver Island Mountains (fig. 16), which 

was later called the Johns Wash Limestone by Robison and 

Palmer (1968). The thin Corset Spring Shale probably correlates with the much thicker olive to tan shale and silty 

crinoidal limestone unit present in the uppermost part of the 

Dunderberg Shale in the Toano Range, which is exposed 

south of Silver Zone Pass.

UPPER-PLATE CAMBRIAN SECTION

A separate Middle and Upper Cambrian stratigraphic 

nomenclature, primarily developed outside of the Wendover 

region, is applied to a largely carbonate section exposed 

above the Pilot Peak detachment. Miller (1983, p. 199), in 

his discussion of the Pilot Range, was the first to note dissimilarities between the unmetamorphosed Upper Cambrian section exposed immediately above the Pilot Peak detachment and the metamorphosed section below it. Similar 

structure and facies are present in the Silver Island Mountains and at the northern end of the Toano Range.

The stratigraphic sequence of Middle and Upper 

Cambrian rocks above the Pilot Peak detachment is fairly 

similar to temporally equivalent sequences in west-central 

Utah and adjacent Nevada. Some previously established 

nomenclature has already been applied in the Wendover 

region, such as the Johns Wash Limestone, Corset Spring 

Shale, and Notch Peak Formation (see Whitebread, 1969). 

Recent geologic mapping by Click (1987) in the northern 

Toano Range and by D.M. Miller (unpub. data) in the Pilot 

Range and Silver Island Mountains has shown that the 

Trippe, Lamb, Big Horse, and Candland units are also 

present regionally. A brief description of each of these previously established units within the Wendover region is 

given here to facilitate comparison with both the lowerplate rocks of the Wendover region and similar facies outside the study region.

Click (1987) used the Orr Formation in her discussion of Upper Cambrian upper-plate rocks in the northern 

Toano Range. The Orr Formation was divided into five 

formal members by Hintze and Palmer (1976); the lower 

four of these members appear to be readily mappable at a

scale of 1:24,000 in the Wendover region. The Orr Formation is raised to group status, with the Big Horse Limestone 

and Candland Shale Members (of the Orr Formation) raised 

to formational rank. The overlying Johns Wash Limestone 

and Corset Spring Shale already are of formational rank in 

east-central Nevada (see Drewes and Palmer, 1957). Strata 

correlative with the Sneakover Limestone Member, the uppermost member of the Orr Formation in Utah, were assigned 

to the Notch Peak Formation by Whitebread (1969) in Nevada. That usage is followed here.

TRIPPE LIMESTONE

The Trippe Limestone was named by Nolan (1935) 

for a 230-m-thick section of medium-gray silty limestone 

and light-gray to white, laminated dolomite in the Deep 

Creek Mountains, Utah. Hintze and Robison (1975) recognized the Trippe Limestone as a widespread unit in eastcentral Utah. In addition, they divided the type section of 

the Trippe into an informal lower limestone member and an 

upper Fish Springs Member.

Miller (1990) has identified the Trippe Limestone in 

the northern Silver Island Mountains at Crater Island, where 

it is the lowest exposed Cambrian unit. Only about 150 m 

of the upper Trippe Limestone is exposed below the Lamb 

Dolomite, and this sequence consists of medium-dark-gray 

limestone and silty limestone. The Trippe Limestone is extended northward into the Silver Island Mountains based on 

stratigraphic position and on such lithologic similarities to the 

Fish Springs Member of the Trippe at its type section as silty, 

oolitic, and oncolitic limestone, and intraformational 

conglomerate. The Trippe in the Silver Island Mountains 

differs from the Trippe at the type section by lacking shale 

and light-colored, laminated dolomite (cryptalgalaminite), 

except locally as clasts in silty limestone within its upper 

part.

Age. No fossils were found in the Trippe Limestone at Crater Island, possibly owing to the extensive recrystallization of the Cambrian section, which is adjacent to 

a Jurassic intrusion (Miller and others, 1990). Hintze (1974) 

and Hintze and Robison (1975) reported a late Middle 

Cambrian Eldoradia fauna from the Fish Springs Member 

of the Trippe Limestone elsewhere.

LAMB DOLOMITE (EMENDED)

The Lamb Dolomite was named by Nolan (1935) 

for a 320-m-thick sequence of light-gray dolomite, much 

of which is highly recrystallized, in the Deep Creek Mountains, Utah. Nolan (1935, p. 13) informally subdivided the 

type section of the Lamb into three distinct lithologies: a 

lower, 150-m-thick, crossbedded, oolitic and oncolitic 

dolomite; a middle, 120-m-thick, mottled and highly re26 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
crystallized dolomite; and an upper, 50-m-thick, thin-bedded dolomite with yellowish-orange to red sandstone, siltstone, and shale. We herein restrict the type section of the 

Lamb Dolomite to include only the purer dolomitic rocks 

of the two lower facies of Nolan (1935) and reassign the 

upper 50 m of sandy dolomite to the Ola Sandstone of this 

report.

The Lamb Dolomite is present in several mountain 

ranges southeast of the type area (Hintze and Robison, 1975) 

and also in the Wendover area. Miller (1990) assigned approximately 75 m of light-gray to white, crystalline dolomite and dolomitic limestone of the unit between the underlying Trippe Limestone and the overlying Big Horse Limestone to the Lamb Dolomite in the northern Silver Island 

Mountains at Crater Island. In the Jenkins Peak section at 

Silver Island (fig. 17) in the Silver Island Mountains, 

Schaeffer (1960, p. 23-24) mapped a 108-m-thick dolomite 

interval as the Dome(?) Formation; these rocks are herein 

assigned to the Lamb Dolomite.

Age. The Lamb Dolomite is largely unfossiliferous, 

and its age is constrained by faunas in the underlying and 

overlying formations. A late Middle Cambrian Eldoradia 

Assemblage-zone fauna is present near the top of the underlying Trippe Limestone in central Utah, and the overlying Big Horse Limestone Member of the Orr Formation in 

western Utah contains trilobites of the Cedaria Assemblagezone. Bick (1966, p. 35) reported Crepicephalus Assemblage-zone trilobites from the upper beds of the Lamb Dolomite in the type area in the Deep Creek Mountains, in 

strata that are now assigned to the Ola Sandstone. Robison 

and Palmer (1968) also collected a species of Crepicephalus 

from rocks herein assigned to the Lamb Dolomite in the 

central Silver Island Mountains. The upper contact of the 

Lamb Dolomite is therefore diachronous and becomes 

younger in a northward direction.

The base of the Cedaria Assemblage-zone has traditionally been used as the base of the Upper Cambrian in 

North America (Lochman-Balk and Wilson, 1958; Robison, 1964), which would place the Lamb Dolomite in the 

Upper Cambrian. However, recently Robison (1984), following a suggestion by Daily and Jago (1975), included 

much of the Cedaria zone within the Middle Cambrian. By 

this revision the Lamb Dolomite could include Middle 

Cambrian beds; we at present adopt this age reassignment 

of the Cedaria zone and consider the Lamb to be Middle 

and Late Cambrian in age.

BIG HORSE LIMESTONE

The Big Horse Limestone Member of the Orr Formation was named by Hintze and Palmer (1976) for a limestone and dolomite sequence ranging from 135 to 270 m in 

thickness in the House Range of west-central Utah. They 

reported that it generally forms bold cliffs of limestone,

silty limestone, and dolomite. Such features as oolites, oncolites, and stromatolites are present in the Big Horse 

Limestone Member.

The unit is here raised to formational rank within 

the Wendover region as the Big Horse Limestone. In the 

northern Silver Island Mountains, Miller (1990) has mapped 

a much faulted section of the Big Horse Limestone at Crater Island, where the unit is approximately 180 m thick. A 

175-m-thick sequence of light- to medium-gray limestone 

and minor dolomite in the Jenkins Peak section at Silver 

Island in the Silver Island Mountains (fig. 17), which 

Schaeffer (1960, p. 25-27) mapped as the Condor Formation and restricted Swasey Limestone, is here reassigned to 

the Big Horse Limestone. In Miners Canyon on the southeast flank of Pilot Peak in the Pilot Range, much faulted, 

light-gray dolomite and recrystallized limestone below the 

Candland Formation and above the Pilot Peak detachment 

are here reassigned to the Big Horse Limestone. In the 

northern Toano Range, Click (1987) mapped a 270-m-thick 

dolomite and limestone unit below the Candland Shale 

Member (of the Orr Formation) as the Big Horse Limestone Member (of the Orr Formation). These rocks are here 

reassigned to the Lamb Dolomite and Big Horse Limestone, undifferentiated.

Age. Robison and Palmer (1968) reported a Crepicephalus Assemblage-zone fauna from about 45 m above 

the base of an undifferentiated lower Upper Cambrian unit 

in the Jenkins Peak section in the central Silver Island 

Mountains, which is here assigned to the Big Horse Limestone. Additional fossils were not found in the unit during 

this study. Hintze and Palmer (1976) noted that, regionally, 

faunas from the Big Horse Limestone Member of the Orr 

Formation range from the upper part of the Cedaria to near 

the top of the Crepicephalus Assemblage-zones of the Upper Cambrian. Thus, the Big Horse Limestone is considered 

to be Late Cambrian in age.

CANDLAND FORMATION

The Candland Shale Member of the Orr Formation 

was named by Hintze and Palmer (1976) for a shale and 

silty limestone sequence approximately 125 m thick in the 

House Range of west-central Utah. They noted that the 

unusually fossiliferous Candland Shale Member is an easily 

mappable unit that forms broad benches and slopes between 

the underlying cliff-forming Big Horse Limestone and 

overlying Johns Wash Limestone Members (of the Orr Formation).

The unit is here raised to formational rank in the 

Wendover region as the Candland Formation. In the Jenkins Peak section at Silver Island in the Silver Island Mountains (fig. 17), the Candland Formation consists of 85 m of 

strata that were mapped as the Wheeler Shale by Schaeffer 

(1960, p. 27-29) and later referred to as the Dunderberg

Candland Formation 27
Shale by Robison and Palmer (1968). Miller (1990) has 

mapped an approximately 60-m-thick section of the 

Candland Formation at Crater Island in the northern Silver 

Island Mountains. In the southern Pilot Range, it consists of 

strata previously assigned to the Dunderberg Shale by 

O'Neill (1968) and Miller (1984) above the Pilot Peak detachment. In the northern Toano Range, strata mapped as 

the Candland Shale Member of the Orr Formation by Click 

(1987) are here assigned to the Candland Formation.

The lower contact of the Candland Formation is 

placed at the base of the thin- to medium-bedded, recessive 

silty limestone above the cliff-forming Big Horse Limestone. The upper contact is gradational and is placed at the 

top of the thin- to medium-bedded silty limestone below 

the massive, recrystallized and locally dolomitic, cliffforming Johns Wash Limestone. The Candland Formation 

thins westward from 85 m in the Jenkins Peak section of 

the Silver Island Mountains to approximately 60 m in the 

northern Toano Range. Thickness measurements in the Pilot Range were precluded by faulting.

An irregular or undulose weathering, thin- to medium-bedded, medium-gray limestone unit, locally containing numerous inarticulate brachiopods, is present in the basal 

few meters of the Candland Formation. Slope-forming, 

laminated to thinly bedded black shale, which weathers light 

olive gray to grayish orange pink, and nodular to thin-bedded argillaceous limestone compose the remainder of the 

formation. Black shale is the main lithology in the lower 

half of the formation, and in the upper half it is subequal 

with argillaceous limestone.

Age. Robison and Palmer (1968) reported trilobites 

of the lower Dicanthopyge Assemblage-zone from strata in 

the central Silver Island Mountains, which they called the 

Dunderberg Shale and are here reassigned to the Candland 

Formation. An Aphelaspis Assemblage-zone fauna was recovered during this study from the basal beds of the Candland Formation in the same section. Additional fossils collected in the Pilot Range south of Pilot Peak represent the 

Dicanthopyge to Dunderbergia Assemblage-zones (A. R. 

Palmer, written commun., 1983). Regionally, the Candland 

Shale Member of the Orr Formation ranges from the uppermost Crepicephalus Assemblage-zone to the middle of the 

Dunderbergia Assemblage-zone (Hintze and Palmer, 1976). 

Thus, the Candland Formation is considered to be entirely 

Late Cambrian in age.

JOHNS WASH LIMESTONE

The Johns Wash Limestone was named by Drewes 

and Palmer (1957) for a 76-m-thick, cliff-forming, light- to 

dark-gray, recrystallized oolitic limestone interval exposed 

in the Snake Range in eastern Nevada. Robison and Palmer 

(1968) identified the Johns Wash Limestone in the Wendover region by applying the name to a prominent 80-mthick, cliff-forming unit of medium-gray limestone that is 

overlain by light-gray to white, recrystallized limestone and 

dolomite in the Jenkins Peak section at Silver Island in the 

Silver Island Mountains (figs. 16, 17); we agree with that 

extension and further extend it to Crater Island (Miller, 

1990). A similar limestone and dolomite unit was assigned 

to the Johns Wash Limestone by O'Neill (1968) and Miller 

(1984) in the southern Pilot Range and was mapped as the 

Johns Wash Limestone Member of the Orr Formation by 

Click (1987) in the northern Toano Range. That unit is here 

assigned to the Johns Wash Limestone.

Age. Drewes and Palmer (1957) reported a Late 

Cambrian Elvinia Assemblage-zone fauna from the upper 

beds of the type section of the Johns Wash Limestone in 

eastern Nevada. The Johns Wash Limestone in the Wendover region appears to be unfossiliferous, possibly owing 

to recrystallization and dolomitization. However, the Johns 

Wash Limestone is considered to be Late Cambrian in age 

because it lies between well-dated Upper Cambrian units 

locally and regionally.

CORSET SPRING SHALE

The Corset Spring Shale was named by Drewes and 

Palmer (1957) for a 20-m-thick unit of olive-gray shale and 

interbedded medium-gray, crystalline limestone in the Snake 

Range of eastern Nevada. Robison and Palmer (1968) designated a 16-m-thick, recessive weathering, silty limestone 

and shale unit in the Jenkins Peak section at Silver Island in 

the central Silver Island Mountains as the Corset Spring 

Shale (fig. 17); we here agree with that assignment. Miller 

(1990) has mapped the Corset Spring Shale at Crater Island 

in the northern Silver Island Mountains. A unit of yellowish-green shale and silty limestone in the northern Toano 

Range was mapped as the Corset Spring Shale Member of 

the Orr Formation by Click (1987); these rocks are here 

assigned to the Corset Spring Shale.

Age. Drewes and Palmer (1957) reported trilobites 

of the Late Cambrian Elvinia Assemblage-zone fauna from 

the type section of the Corset Spring Shale in the Snake 

Range. Robison and Palmer (1968) also reported an Elvinia 

fauna from the Corset Spring Shale at Silver Island in the 

Silver Island Mountains. An Elvinia fauna is also present in 

green shales of the uppermost Dunderberg Shale south of 

Silver Zone Pass in the Toano Range. Thus, the Corset 

Spring Shale is considered to be Late Cambrian in age.

NOTCH PEAK FORMATION

The Notch Peak Formation was named by Walcott 

(1908b) for exposures in the House Range; it has been redefined and subdivided into three formal members by Hintze 

and others (1988). The Notch Peak, which is one of the

28 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
most widespread units in the central Great Basin, caps all 

of the Cambrian sequences in the Wendover region. However, lithology and outcrops of the formation vary locally.

Schaeffer (1960) was the first to identify the Notch 

Peak Formation in the Jenkins Peak section at Silver Island 

in the central Silver Island Mountains, and Miller (1990) 

has mapped the formation at Crater Island to the north. 

O'Neill (1968) and Miller (1984) mapped the Notch Peak 

Formation near Miners Canyon in the Pilot Range. Pilger 

(1972) and Click (1987) also mapped the formation in the 

northern Toano Range. We here agree with these assignments in each of these areas. It is also present in the northern Goshute Mountains (Day and others, 1987). In all of 

these areas, the Notch Peak forms steep, massive cliffs consisting of both limestone and dolomite. Just south of Silver 

Zone Pass in the Toano Range (fig. 14), the Notch Peak is 

siltier and forms steep slopes and ridges above the 

Dunderberg Shale. It also is less stromatolitic than in surrounding sections.

Age. Robison and Palmer (1968) reported a fauna 

from the basal part of the Notch Peak Formation in the 

Jenkins Peak section at Silver Island in the central Silver 

Island Mountains that represents the Taenicephalus Assemblage-zone of the Upper Cambrian. Schaeffer (1960) reported 

fossils assignable to the overlying Saratogia and Saukia 

Assemblage-zones from the middle part of the Notch Peak 

Formation in the same area. Late Cambrian euconodonts 

collected from the Notch Peak in the Toano Range just 

south of Silver Zone Pass were questionably assigned to 

Proconodontus and given a color alteration index of 6 by J. 

M. Repetski (written commun., 1984). Miller (1969), J.F. 

Miller and others (1982), and Hintze and others (1988) noted 

that the Cambrian-Ordovician boundary is near the top of 

the Notch Peak near its type locality in the southern House 

Range. Therefore, the Notch Peak Formation is considered 

to be Late Cambrian and Early Ordovician in age.

DEPOSITIONAL ENVIRONMENTS

Perhaps the greatest diversity of Cambrian depositional environments in the Great Basin is present in the 

Wendover region. Although a detailed sedimentological 

study of these rocks by McCollum (1987; McCollum and 

others, 1988) is still ongoing, a summary of the depositional environments is given here to facilitate an understanding of the facies distributions and formational designations applied in this report. It is still unclear as to what 

extent Mesozoic and younger structure modified the original geographic distribution.

The lithofacies patterns and environmental interpretation of the Cambrian sequence in the Wendover region 

are consistent with a paleogeographic setting in an outer shelf 

on a passive margin. Late Proterozoic rifting and cratonal 

emergence produced an immense braid-plain to shallowmarine clastic wedge along the Cordilleran margin (Stewart, 

1976), which persisted until a carbonate platform developed 

and gradually moved cratonward during the Cambrian. The 

heterogeneity of facies developed within the Cambrian of 

the Great Basin reflects the diversity of depositional environments present on a passive margin at low latitudes.

The Late Proterozoic McCoy Creek Group and the 

overlying Late Proterozoic and Early Cambrian Prospect 

Mountain Quartzite span the time interval during which 

continental rifting gave way to development of a passive 

continental margin in the northern Great Basin. The Prospect Mountain Quartzite in the Wendover area is composed 

entirely of siliciclastic sedimentary rocks characterized by 

planar and shallow trough crossbeds and horizontal stratification. Distinct channels of quartzite-pebble conglomerate, 

in places accompanied by thin, dark argillite at their margins, 

are interpreted as representing braided-stream and overbank 

deposits. Bimodal low-angle crossbedding, indicative of a 

shallow marine or estuarine environment, is present regionally in the upper part of the Prospect Mountain Quartzite 

(Schneck and McCollum, 1985; Schneck, 1986). Thus, facies 

development within the Prospect Mountain Quartzite in the 

Wendover area is consistent with the regionally extensive 

braid-plain to shallow-marine paleoenvironmental interpretation.

In the central Great Basin, a transitional facies of 

mixed siliciclastics and carbonates, assignable to the Lower 

and Middle Cambrian Pioche Formation, exists between the 

quartz arenites of the Prospect Mountain Quartzite and the 

overlying carbonate platform. The Pioche Formation is generally fossiliferous and was deposited under shallow-marine conditions. A shallow subtidal Cruziana ichnofauna is 

present along bedding surfaces in the clastic facies, whereas 

algal structures are present in the bioclastic carbonates. In 

addition, a fairly abundant and diverse benthic shelly fauna, 

ranging from ti&Bonnia-Olenellus to Albertella Assemblage 

zones, has been reported from the Pioche Formation regionally (Hintze and Robison, 1975, fig. 3).

Deep-water deposits of the Killian Springs Formation overlie the Prospect Mountain Quartzite in the Wendover area. These deposits consist of dark-gray to black, 

laminated, graphitic siltstone; impure limestone; quartzgranule conglomerate; and minor silty limestone that contains only siliceous sponge spicules. The dark, virtually unfossiliferous facies of the Killian Springs Formation are in 

sharp contrast to the lighter colored, more fossiliferous rocks 

of the Pioche Formation, as exposed from the Deep Creek 

Mountains southward.

The onset of deep-water deposition appears to be 

due to rapid subsidence, resulting from downfaulting along 

the outer shelf in the northern Great Basin. The area where 

this structural downwarping occurred is not exposed, but the 

presence of a coarser, more proximal facies in the Killian 

Springs Formation at Tetzlaff Peak, north of Wendover, 

suggests that the flexure exists along the southeast margin

Depositional Environments 29
of the study area. Once established, this deep outer-shelf 

environment persisted from late in the Early Cambrian to 

well into the Middle Cambrian, a duration of at least 15 m.y.

Although it is difficult to gauge depth, sediments 

within the Killian Springs Formation and the Toano Limestone appear to have been deposited in an anoxic environment below storm-wave base. There is no indication of 

biotic or abiotic reworking of the sediment. The absence of 

tempestites and both shelly and ichnofossils from these 

laminated sediments suggests depths greater than stormwave base.

A shallow-water carbonate platform developed 

southeast of the Wendover area during the early Middle 

Cambrian Albertella Assemblage-zone. Terrigenous elastics 

that bypassed the platform, combined with carbonate muds 

generated from it, settled out as laminated, hemipelagic 

sediments of the Toano Limestone. Graded bedding is apparent in some of the silty limestone and may be the result 

of distal turbidity currents.

Although much of the Toano Limestone is laminated, trough crossbedding is present at two horizons low 

in the type section. Soft-sediment deformation is found 

throughout the Toano but is most common in the middle 

one-third of the formation. Semicoherent to incoherent flows 

as thick as 1.5 m are common (McCollum and McCollum, 

1984). The direction of transport, based on axes of softsediment folds, was to the northwest.

The Toano Limestone was deposited under unrestricted open-marine conditions, as evidenced by a medial 

Middle Cambrian cosmopolitan, pelagic, agnostoid and 

polymeroid trilobite fauna. The absence of a benthic fauna 

may be attributed to substrate instability and high fluidity 

within the sediments. Although carbonate muds of the Toano 

Limestone must have been generated from a nearby carbonate platform, the lack of redeposited oolites or algal debris, 

coupled with the slope needed to generate debris flows, 

suggests deposition in the lower part of a northwest-facing, 

distally steepened carbonate ramp (McCollum and 

McCollum, 1984).

The Clifside Limestone records a shallowing-upward 

sequence in response to an oceanward progradation of the 

carbonate platform across the Wendover area. Storm-generated oolitic grain flows, some of which include algal mat 

rip-up clasts, flowed downslope and are interbedded with 

the hemipelagic ramp sediments of the lower limestone 

member of the Clifside.

The first appearance in the Wendover area of a shallow subtidal to peritidal environment occurs near the middle 

of the Clifside Limestone, deposited during the middle 

Bolaspidella Biochron. A relatively thin, laminated dark 

shale, overlain by rip-up clasts, at the base of the (middle) 

silty limestone and shale member of the Clifside may have 

been deposited as a flood sheet. A shoaling-upward sequence developed above this, beginning with bioturbated 

lime muds and crossbedded oolitic sands, overlain by intertidal domal stromatolites and supratidal fenestral lime muds 

and dolomitic algal mats. The sequence is overlain by a 

silty, laminated limestone virtually devoid of benthic forms 

except linguloid brachiopods, which can tolerate conditions 

found in a restricted intrabasin or lagoonal environment. 

The upper limestone member of the Clifside represents a 

gradual shallowing, as a sequence of shallow subtidal, bioturbated, silty lime muds, and supratidal fenestral lime muds, 

covered by dolomitic algal mats, prograded across the lagoonal deposits.

The Morgan Pass Formation and Trippe Limestone 

in the Wendover area are largely time equivalent but differ 

sedimentologically. Strata of the Morgan Pass Formation 

are mainly terrigenous silts and muds, whereas the Trippe 

Limestone is almost exclusively burrowed and algal carbonate. Despite the differences in lithology, both formations apparently were deposited under shallow-water conditions adjacent to one another in the study area.

The influx of terrigenous mud and silt of the Morgan Pass Formation smothered the outer part of the carbonate platform. Shallow-water conditions persisted, however, 

despite the decrease in carbonate production caused by the 

dampening effect of this clastic blanket Except for the 

presence of inarticulate brachiopods on some bedding surfaces, the muds are devoid of benthic fauna, suggesting a 

restrictive environment. The rhythmic nature of the thin- to 

medium-bedded calcareous siltstones and the presence of 

low-amplitude hummocky layering suggest flood deposits 

that were tidally reworked.

Occasionally storm tracks cut across the outer 

platform, breaching the oolitic shoal barrier and spreading 

coarse carbonate debris (rip-up clasts) and oolitic shoal sands 

across the normally placid muddy lagoonal environment. 

These storms probably improved marine circulation in the 

lagoons and certainly provided a firmer substrate, allowing 

formation of microbial bioherms. Some of the columnar 

stromatolites and thrombolites grew to 1 m in height before 

being smothered by the next substantial influx of terrigenous mud.

The Trippe Limestone was deposited in the area of 

the carbonate platform not blanketed by terrigenous elastics 

of the Morgan Pass Formation but under similar environmental conditions. Lime muds continued to accumulate in a 

shallow subtidal environment where storms periodically 

covered these burrowed muds with rip-up clasts and redeposited oolitic sands. Microbial mats commonly colonized 

the surface of these redeposited sediments, although biohermal builders are absent. Fenestral fabric also developed in 

the lime muds under peritidal conditions.

The Decoy Limestone preserves a deepening-upward 

or retrogressive carbonate sequence. The basal deposits of 

the Decoy record the cratonward migration of the oolitic 

and oncolitic shoal environment. This is succeeded by burrowed peloidal lime muds deposited under deepening 

subtidal conditions.

30 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Increasing water depth brought about the first 

drowning of the carbonate platform since its establishment 

in the Wendover area. This transgression brought openmarine conditions across the outer edge of the carbonate 

platform during the Lejopyge laevigata Biochron. These 

deeper water deposits and those formed during the subsequent shallowing event are recorded within the strata of the 

Shatter Formation.

Strata in the lower half of the Shafter Formation 

were deposited as laminated calcareous mud and silt. Unrestricted marine conditions must have been present to account 

for the cosmopolitan, pelagic agnostoids. However, the absence of a benthic fauna and of tempestite beds, in a lowlatitude region obviously affected by storms, suggests that 

the sediments may have been deposited under anoxic conditions below storm-wave base. In the upper half of the Shafter 

Formation, terrigenous silts increased and the bedding became distinctly hummocky as a result of wave action. 

Shallowing into the zone of wave mixing may also account 

for the addition of endemic, benthic, polymeroid trilobites 

to the cosmopolitan agnostoid fauna.

A continuous sequence of shallow subtidal to peritidal carbonates of the Lamb Dolomite were being deposited 

inboard of the transgression that brought about the outershelf drowning recorded in the Shafter Formation. Shallow 

subtidal, burrowed lime muds; migrating oolitic and oncolitic shoals; and peritidal, fenestral lime muds and dolomitic algal mats dominated the carbonate platform. The lack 

of terrigenous silt may have contributed to the extensive 

synsedimentary dolomitization.

The carbonate platform again prograded completely 

across the Wendover area during the early Late Cambrian. 

Facies patterns began to have a more regional extent, and 

several formational designations from the central Great Basin can be applied to the Wendover area. Some of the Late 

Cambrian paleoenvironments present within the Wendover 

area have also been studied in detail to the south in westcentral Utah (see Robison and Rowell, 1976; Taylor, 1989).

Shallow subtidal to peritidal conditions existed in 

the Wendover area during the Crepicephalus Biochron. Initial deposits consist of shallow subtidal, burrowed lime muds 

and peritidal fenestral muds and algal mats, overlain by 

oolitic shoal deposits in the Lion Spring Limestone, the 

lower half of the Oasis Formation, and the uppermost Lamb 

Dolomite. Carbonate production was then locally interrupted 

by an influx of terrigenous elastics across the southern part 

of the Wendover area.

The Ola Sandstone represents a tidally influenced, 

mixed clastic and carbonate environment. Broad channels 

and sheets of quartz sand and silt, interbedded with oolitic 

sands, formed along the outer-platform margin from the 

northern Goshute Mountains southward to the Deep Creek 

Mountains and eastward to the Dugway Range. Several 

channeled quartz-sand beds in the lower strata of the Big 

Horse Limestone in the Silver Island Mountains may represent the northern extent of this coarse terrigenous influx. A 

prominent interval of calcareous siltstone in the middle of 

the Oasis Formation may also represent distal elastics that 

were locally impounded behind an oolitic shoal barrier along 

the outer shelf.

With the cessation of clastic input, a retrogressive 

carbonate sequence was deposited across the area. Oolitic 

shoals migrated cratonward and were replaced by subtidal, 

burrowed lime muds of the Goshute Limestone, the upper 

Oasis Formation, and most of the Big Horse Limestone. 

These muds are overlain by laminated lime muds and shales 

in what was the last and most widespread of the Cambrian 

marine transgressions in the Great Basin.

Platform drowning across the Wendover area had 

been accomplished by the beginning of the Dicanthopyge 

Biochron. This terrigenous event is recorded in strata of the 

Dunderberg Shale and Candland Formation. These formations are composed largely of laminated elastics and interbedded carbonate debris flows and tempestites.

Paleoenvironmental conditions were initially similar 

for both the Dunderberg Shale and Candland Formation, 

although the drowned environment represented by the latter 

was of shorter duration and in a more cratonward position. 

Barren, black, laminated muds, deposited under anoxic conditions, are interbedded with thin bioclastic limestones. These 

carbonates are sometimes graded and contain shell lags of 

disarticulated polymeroid trilobites, and they probably represent both debris flows and tempestites.

The carbonate platform (Johns Wash Limestone) 

prograded across the open-shelf sediments of the Candland 

Formation during the middle Dunderbergia Biochron. The 

Johns Wash preserves a shallowing-upward sequence of 

bioturbated lime mud, overlain by oolitic shoal deposits. 

Cratonally derived mud and silt of the Corset Spring Shale 

covered the carbonate platform during the Elvinia Biochron.

This newly established shallow carbonate platform 

did not extend completely across the Wendover area. Deeper 

water, open-shelf conditions continued into the Elvinia Biochron in the Dunderberg Shale. By the end of the Elvinia 

Biochron, the prograding carbonate platform (Notch Peak 

Formation) had completely covered the Wendover area, and 

shallow subtidal to peritidal deposits continued into the Early 

Ordovician.

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MEASURED SECTIONS

All sections were measured by McCollum with a 

1.5-m Jacob staff. The carbonate classification by Dunham 

(1962) was used. The degree of bioturbation was based on 

the ichnofabric index of Droser and Bottjer (1986). Fossil 

identifications were made by A.R. Palmer, R.A. Robison, 

and A.J. Rowell.

Section 1

Type section of the Killian Springs Fonnation and partial reference section 

of the Toano Limestone, Pilot Range. Section located in NW VJ NW 1/ sec. 

21 and S Vi SE V* sec. 16, T. 5 N., R. 19 W., along a northeast-trending 

ridge starting at 6,500 ft and ending at 7,700 ft, Patterson Pass 7/2-minute 

quadrangle, Nevada-Utah (fig. 7). Measured in June 1984.

Toano Limestone (Middle Cambrian) (incomplete): Meters 

3. Lime mudstone, dark-gray (N3) to medium-lightgray (N6); dark-yellowish-orange (10 YR 6/6) 

to light-brown (5 YR 5/6) silty laminations; 

measurement terminated in synclinal axis ...... 260

Incomplete thickness of Toano

Limestone .......................................... 260

Gradational contact.

Killian Springs Formation (Lower and Middle Cambrian): Meters 

2. Siltstone, phyllitic, grayish black (N2); and medium-gray (N5), platy lime mudstone, containing sponge spicules................................... 175

1. Siltstone, fine-grained sandstone, and phyllite, 

grayish-black (N2) to medium-gray (N5), 

hackly to fissile; dark-yellowish-orange (10 

YR 6/6) to light-brown (5 YR 5/6) iron 

staining common; moderately to highly 

cleaved locally................................................ 125

Total thickness of Killian Springs

Formation........................................... 300

Sharp conformable contact.

Prospect Mountain Quartzite (Late Proterozoic and

Lower Cambrian) (not measured)

Section 2

Type section of the Toano Limestone and reference section of the Killian 

Springs Formation, Toano Range. Section measured across the northern 

half of sec. 4, T. 35 N., R. 68 E., on a prominent east-trending ridge at 

6,600-ft contour and ending at Hill 7129, Silver Zone Pass 7Vi-minute 

quadrangle, Nevada (fig. 8). Measured in July 1983.

Clifside Limestone (Middle Cambrian) (not measured) 

Conformable contact.

Toano Limestone (Middle Cambrian): Meters

8. Silty lime mudstone, medium-gray (N5) to darkgray (N3), with very pale orange (10 YR 8/2) 

to grayish-brown (5 YR 3/2) silty laminated 

beds. Occasional megaslumps, including one 

in which several lithified, imbricated, silty lime 

mudstone clasts align at a 60° angle with a 

southeastward dip, indicate movement to the 

northwest; silicified agnostoids, including 

Ptychagnostus atavus, 20 m above base, and 

silicified polymeroid trilobites, including 

Bolaspidella, in upper 30 m............................ 225

7. Silty lime mudstone, medium-dark-gray (N4), 

with light-olive-gray (5 Y 6/1) silty laminations. Interval is characterized by soft-sediment 

megaslumps as thick as several meters, separated by horizontally laminated beds. Megaslumps range from semicoherent to incoherent, some with prominent Z-folds................... 315

6. Silty lime mudstone, medium-gray (N5) to darkgray (N3), with very pale orange (10 YR 8/2) 

to grayish-brown (5 YR 3/2) silty laminated 

beds; occasional megaslumps and black phyllitic siltstone beds; poorly preserved Middle 

Cambrian silicified ptychopariids and agnostoids 10 m below top....................................... 140

5. Silty lime mudstone, medium-dark-gray (N4), 

with light-olive-gray (5 Y 6/1) silty laminations. Interval is characterized by soft-sediment 

megaslumps, as thick as several meters, separated by horizontally laminated beds.

34 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Toano Limestone (Middle Cambrian): Continued Meters 

Megaslumps range from semicoherent to incoherent, some with prominent Z-folds.............. 50

4. Silty lime mudstone to calcareous siltstone, medium-gray (N5) to dark-gray (N3); silt laminae 

grayish brown (5 YR 3/2) to very pale orange 

(10 YR 8/2); annealed microfaults and minor 

soft-sediment deformation present throughout; 

bidirectional trough cross-stratification to the 

northwest and southeast; minor rotational 

slumps present................................................ 110

3. Argillaceous lime mudstone, dark-gray (N3) to 

black (Nl), with thin phyllitic shale interbeds. 

Finely disseminated white mica gives a reflective sheen; distinct soil color change at the 

formational contact from medium gray (N5) 

below to pale brown (5 YR 5/2) above; 

forms slopes.................................................... 10

Total thickness of Toano Limestone ....... 850

Gradadonal contact.

Killian Springs Formation (Lower and Middle Cambrian) (incomplete):

2. Calcareous siltstone to lime mudstone, mediumdark-gray (N4) to dark-gray (N3), with occasional thin interbeds of laminated fine-grained 

sandstone; clays altered to white micas, floating, generally not oriented; forms slopes 

and low-lying hills.......................................... 95

1. Siltstone, phyllitic to micaceous, medium-darkgray (N4) to dark-gray (N3), thin to platy, occasionally blocky, microlaminated; thin (15- 

cm) interbeds of fine-grained, dark-gray (N3) 

sandstone and occasional argillaceous limestone beds. Siltstone and fine-grained 

sandstone weather to blocky slopes ................ 155

Incomplete thickness of Killian Springs

Formation ........................................ 250

B ase of section covered.

Section 3

Type section of Clifside Limestone, Toano Range. Section located in SE'/ 

sec. 4 and SW 1A sec. 3, T. 35 N., R. 68 E., Silver Zone Pass TA -minute 

quadrangle, Nevada (fig. 8). Measured in July 1984. The type Clifside 

Limestone contains medium- to thin-bedded lithologic units that have a 

distinctly striped appearance. In the descriptions below, brown, silty beds 

alternating with gray limestone are referred to as "tiger-striped," and lightgray, oolitic grainstone beds alternating with gray limestone are referred to 

as "zebra-striped."

Top of section faulted against Clifside Limestone and

Morgan Pass Formation. Meters 

Clifside Limestone (Middle Cambrian) (incomplete): 

Upper limestone member:

14. Lime mudstone to wackestone, medium-gray 

(N5) to medium-dark-gray (N4), laminated to 

undulose, with yellowish-gray (5 Y 7/2) silt; 

fenestral fabric in lower 60 m; massive 

texture............................................................. 210

Incomplete thickness of upper limeUpper limestone member. Continued Meters 

stone member..................................... 210

Silty limestone and shale member:

13. Lime mudstone to packstone, medium-gray 

(N5); interbedded with calcareous siltstone, 

light-brown (5 YR 5/6) to moderate-brown (5 

YR 4/4), undulose to laminar; "tiger-stripe" 

facies............................................................... 20

12. Lime mudstone to wackestone, medium-darkgray (N4) to dark-gray (N3), with prominent 

grayish-orange (10 YR 7/4) silty laminations; 

contains inarticulate linguloid brachiopods and 

marjumid trilobites in upper 6 m .................... 70

11. Lime mudstone to wackestone, medium-lightgray (N6) to medium-dark-gray (N4); stromatolitic, diffuse silty laminae, with fenestral 

fabric; oncolitic beds 20 m above base and in 

uppermost meter, oolitic grainstone and flat 

pebble limestone conglomerate (tempestites) 

present............................................................ 75

10. Phyllitic siltstone and shale, black (Nl); 

interbedded with thin to nodular lime mudstone, dark-gray (N3); forms saddles on 

dip-slope ridges............................................... 10

Total thickness of silty limestone and

shale member..................................... 175

Lower limestone member

9. Lime mudstone to grainstone, medium-gray (N5) 

to medium-light-gray (N6); oolite beds at 32- 

36 m, 9-14 m, and 0 5 m; fenestral fabric at 

14-32 m; silty beds at 5-9 m; "zebra-stripe" 

facies............................................................... 38

8. Lime mudstone to packstone, medium-gray (N5); 

interbedded with calcareous siltstone, lightbrown (5 YR 5/6) to moderate-brown (5 YR 

4/4); fenestral fabric at 15-19 m; "tiger-stripe" 

facies............................................................... 24

7. Lime mudstone to grainstone, medium-gray (N5) 

to medium-light-gray (N6); oolite beds at 43- 

44 m and 0 13 m; fenestral fabric at 13-43 m; 

"zebra-stripe" facies........................................ 44

Section offset 400 m southward along ridge crest. 

Measurement resumed along a prominent eastward spur.

6. Lime mudstone to packstone, medium-gray (N5); 

interbedded with calcareous siltstone, lightbrown (5 YR 5/6) to moderate-brown (5 YR 

4/4), undulose to laminar; "tiger-stripe" 

facies............................................................... 12

5. Lime mudstone to grainstone, medium-gray (N5) 

to medium-light-gray (N6); thin, dark-yellowish-orange (10 YR 6/6) to grayish-orange (10 

YR 7/4), undulose silty layers. Oolitic 

grainstones in tabular beds or discrete shallow 

troughs that have sharp parallel contacts with 

adjacent laminated layers; stromatolitic layer 

near top; "zebra-stripe" facies......................... 22

4. Wackestone to packstone, medium-gray (N5); 

layers of silt and fine sand, light-brown (5 YR

Measured Sections 35
Lower limestone member Continued Meters 

5/6) to moderate-brown (5 YR 4/4), undulose 

to laminar; top 7 m largely covered; at 30 m 

and 31.5 m above base, rip-up clasts (storm 

deposits) 10 and 15 cm thick; "tiger-stripe" 

facies............................................................... 49

3. Lime mudstone to grainstone, medium-gray (N5) 

to medium-light-gray (N6); thin, dark-yellowish-orange (10 YR 6/6), undulose silty layers. 

Oolitic grainstones are tabular and present in 

discrete shallow troughs; at 9 m above base, 

rip-up clasts (storm deposit) 10 cm thick; 

"zebra-stripe" facies........................................ 18

2. Wackestone to packstone, medium-gray (N5); 

layers of silt and fine sand, light-brown (5 

YR 5/6) to moderate-brown (5 YR 4/4), 

undulose to laminar, "tiger-stripe" facies ....... 18

1. Lime mudstone to grainstone, medium-gray (N5) 

to medium-light-gray (N6); thin, dark-yellowish-orange (10 YR 6/6), undulose silty layers. 

Oolitic grainstones are tabular and present in 

discrete shallow troughs; oolite beds at 39.2- 

39.3 m, 37.5-37.56 m, 36.25-36.35 m (planar 

bottom), 35.4-35.6 m, 33.85-33.9 m, 33.5- 

33.65 m (channeled at top), 31.85-32.05 m, 

30.85-31.1 m, 30-30.15 m, 27.4-27.6 m, 12.2- 

12.4 m, 9.2-9.3 m, and 6.4-6.5 m; "zebrastripe" facies................................................... 40

Total thickness of lower limestone

member............................................... 265

Incomplete thickness of Clifside Limestone 650

Gradational contact.

Toano Limestone (not measured)

Section 4

Type section of the Morgan Pass Formation, Decoy Limestone, Shatter 

Formation, Lion Spring Limestone, Ola Sandstone, and Goshute 

Limestone, and partial reference section of the Dunderberg Shale just west 

of Morgan Pass, Goshute Mountains. Section located in S Vi sec. 21, T. 32 

N., R. 68 E., along northern flank of Hill 8018 in Morgan Pass 7K-minute 

quadrangle, Nevada (fig. 12). Measured in July 1985.

Pogonip Group (Lower Ordovician) (incomplete): Meters 

25. Lime mudstone to packstone, medium-dark-gray 

(N4); weathers medium-light-gray (N6); chert 

layers 5 cm thick, some discontinuous chert 

nodules; highly folded and crumpled at base, 

probably owing to Tertiary detachment 

faulting............................................................ 15

Incomplete thickness of Pogonip Group. 15

Faulted contact.

Dunderberg Shale (Upper Cambrian):

24. Largely covered interval; float composed of 

dark-gray (N3), platy limestone and black 

shale; forms slopes; limestone float highly 

fossiliferous; trilobites include Homagnostus, 

Pseudagnostus, Prehousiat, and Tumicephalus .......................................................... 1QQ

Dunderberg Shale (Upper Cambrian): Continued Meters 

Incomplete thickness of Dunderberg

Shale.................................................. 100

Conformable contact.

Goshute Limestone (Upper Cambrian):

23. Wackestone to packstone, medium-gray (N5); 

some silty mottled (ichnofabric 3) intervals. 

Oncolites and a Crepicephalus Assemblagezone fauna, including Tricrepicephalus, 

Angulotreta cf. A. postapicalis Palmer, 

Kingstonia, and Opisthotreta, present in upper 

10 m; forms the highest gray massive cliff..... 65 

Total thickness of Goshute Limestone.... 65

Conformable contact.

Ola Sandstone (Upper Cambrian):

22. Calcareous siltstone, quartz sandstone, and silty 

limestone, dark-yellowish-orange (10 YR 6/6) 

to light-brown (5 YR 5/6) and grayish-red (10 

R 4/2). Oolitic packstone to grainstone at 57 

57.5 m, 44-^14.5 m, 37-37.5 m, and 33-34.5 

m; trilobite packstone at 56 m contains numerous specimens of Tricrepicephalus; forms 

a prominent reddish-orange cliff..................... 60

Total thickness of Ola Sandstone............ 60

Conformable contact.

Lion Spring Limestone (Upper Cambrian):

21. Wackestone to grainstone, medium-gray (N5), 

oolitic; indistinct silty mottling (ichnofabric 

3 and 4) and thin siltstone beds; weathers 

moderate reddish orange (10 R 6/6) and grayish orange (10 YR 7/4) to dark yellowish 

orange (10 YR 6/6); forms small, cliffy 

ledges.............................................................. 45

20. Silty wackestone to packstone, dark-gray (N3); 

weathers medium dark gray (N4). Silt content 

decreases upwards; fenestral fabric intermixed 

with silty mottles (ichnofabric 3 to 4); oncolites; trilobite hash near top. Upper half forms 

a bluish-gray cliff............................................ 40

Total thickness of Lion Spring Limestone 85

Conformable contact.

Shafter Formation (Middle and Upper Cambrian):

19. Lime mudstone, medium-gray (N5); and calcareous siltstone, grayish-orange (10 YR 7/4) to 

dark-yellowish-orange (10 YR 6/6); thin to 

medium bedded, with horizontal burrows 

(ichnofabric 2) on some bedding planes; forms 

low cliffs. Unit contains a sparse fauna, including Clavagnostus and an unidentified 

cedariid trilobite.............................................. 63

18. Covered interval; platy silty limestone

float................................................................. 6

17. Lime mudstone to wackestone, medium-darkgray (N4); becomes more mottled, less laminated upward. Basal 13 m form ledgy cliffs,

36 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Shafter Formation (Middle and Upper Cambrian): 

Continued Meters 

13 22 m form slopes, and uppermost 8 m 

form ledgy cliffs ............................................. 30

16. Covered interval............................................... 9

15. Lime mudstone to wackestone, medium-darkgray (N4); silty layers grayish orange (10 YR 

7/4); occasional burrows. Cedaria Assemblagezone fauna includes Cedaria prolificat, 

Lonchocephalus sp., Modocia sp., Clavagnostus sp., Proagnostus bulbiist, Oedorhachis sp., 

Anabolotreta sp., Angulotreta sp., andMicromitra sp.; intermittent exposures in a recessive 

slope; partially covered. Unit forms small 

ledges.............................................................. 77

14. Lime mudstone to packstone, medium-dark-gray 

(N4); weathers medium gray (N5); mediumbedded silty layers, moderate-yellowish-brown 

(10 YR 5/4). Bolaspidella Assemblage-zone 

fauna at 6 m above base includes marjumid 

trilobites and a diverse inarticulate brachiopod 

fauna, including Acrothele, Dictyonina, 

Linnarssonia, Picnotreta, Prototreta, 

linguloids, and several species of acrotretids.. 15 

Total thickness of Shafter Formation...... 200

Conformable contact.

Decoy Limestone (Middle Cambrian):

13. Lime mudstone to packstone, recrystallized, 

medium-gray (N5); weathers medium light 

gray (N6); silt grayish orange (10 YR 7/4); 

distinct, slightly undulatory bedding less than 

3.5 cm thick; horizontal burrows (ichnofabric 

2). Lower 7 m contain abundant oncolites; becomes less silty and progressively recrystallized and dolomitized toward the top; forms 

massive gray cliff............................................ 60

Total thickness of Decoy Limestone....... 60

Conformable contact.

Morgan Pass Formation (Middle Cambrian):

12. Calcareous silts tone, silty lime mudstone, and 

wackestone, with interbeds of algal packstone 

and oolitic grainstone, medium-dark-gray (N4) 

to medium-light-gray (N6); rip-up beds 

(tempestites); clasts at high angle to bedding 

in basal 0.5 m; highly bioturbated (ichnofabric 

3 to 4) silty wackestone at 0.5-1 m; rip-up bed 

(tempestite), flat-lying algal clasts at 1-1.25 

m; oolitic grainstone at 1.25-1.6 m; molded 

(ichnofabric 3) and semicoherent laminae with 

stromatolites, 25 cm diameter, near the top at 

1.6-2.5 m; oolitic grainstone infilling between 

stromatolites; surface relief on stromatolite 

heads as much as 10 cm; light-brown (5 YR 

5/6) siltstone with thin to discontinuous, lightolive-gray (5 Y 6/1) silty lime mudstone at 

2.5-16 m; bedding thickness generally 3 cm or 

less; thin (10-cm-thick) beds of rip-up clasts 

at 5.5 m and 6 m; oolitic grainstone at 12-13

Morgan Pass Formation (Middle Cambrian): 

Continued Meters 

m; layers of domal stromatolites, 25 cm diameter, which overlie several beds of rip-up clasts 

at 16-19 m. Fauna includes Eldoradia and 

Lingulella; small horizontal burrows 

(ichnofabric 2) on some bedding planes 

throughout unit............................................... 19

11. Covered interval; silty and platy limestone

float; occasional small discontinuous outcrops 30

10. Silty lime mudstone, medium-dark-gray (N4); 

weathers light gray (N7); thicker bedded and 

less silty than unit 7; horizontal burrows (ichnofabric 2) present.............................................. 27

9. Covered interval; silty lime chips and platy limestone in float................................................... 20

8. Silty lime mudstone, medium-dark-gray (N4), 

which weathers light gray (N7); grayish-orange 

(10 YR 7/4) calcareous siltstone; and pale-olive 

(10 Y 6/2) shale; thinly bedded, with parallel 

laminations. Carbonate interbeds are 3 cm or 

less in thickness; rip-up clasts (tempestites), 

10 cm thick, at 2 m, 9 m, and 18 m above 

base; siliceous shale 26 30 m above base....... 35

7. Covered interval; silty limestone, calcareous siltstone, and shale float; slope surface hummocky, 

appears to be a recent rotational slide ............. 30

6. Silty lime mudstone, medium-dark-gray (N4); 

weathers light gray (N7); mottled (ichnofabric 

3) to thinly bedded.......................................... 6.5

5. Calcareous siltstone, oolitic grainstone, and trilobite packstone of the Bolaspidella Assemblage-zone; largely covered............................ 9

4. Calcareous siltstone and shale, grayish-orange 

(10 YR 7/4) to dark-yellowish-orange (10 YR 

6/6); and oncolitic wackestone to oolitic grainstone, medium-dark-gray (N4) to mediumlight-gray (N6); basal meter calcareous siltstone 

and shale, overlain by 0.5 m of oolitic grainstone, followed by 1 m of silty mottled limestone. Above this is 1.5 m of oncolitic packstone, topped by a 25-cm-thick domal 

stromatolite bed in which the heads weather 

in relief............................................................ 4.25

3. Silty lime mudstone to oolitic grainstone, medium-light-gray (N6) to medium-dark-gray (N4). 

Silty layers and mottles are dark yellowish orange (10 YR 6/6). Basal 0.5 m is wackestone 

to packstone with silty mottles (ichnofabric 3 

to 4), overlain by 1 m of oolitic grainstone and 

0.5 m of oncolitic wackestone to packstone. 

Above this is a 1-m-thick unit of domal stromatolites, with individuals as wide as 0.5 m, 

and silty limestone between individual heads. 

A meter of oncolitic limestone overlies the 

stromatolites and is overlain by a 25-cm-thick 

domal stromatolite layer in which the heads 

weather in relief. Unit forms a prominent 

ridge................................................................ 4.25

2. Shale, calcareous siltstone, and silty lime mudMeasured Sections 37
Morgan Pass Formation (Middle Cambrian): 

Continued Meters 

stone; silt beds pale yellowish orange (10 YR 

8/6); weather moderate reddish brown (10 R 

4/6) to dark yellowish orange (10 YR 6/6); at 

9 m above base, outcrop of oncolitic packstone, 

medium-dark-gray (N4) to medium-gray (N5); 

small silty lime chips, 1 cm average, in float; 

mostly covered................................................ 40

Total thickness of Morgan Pass Formation 225

Conformable contact.

Clifside Limestone (Middle Cambrian) (incomplete):

I. Lime mudstone to packstone, silty, medium-darkgray (N4); weathers to light gray (N7); lightgray (N7) silty mottles (ichnofabric 4 and 5); 

fenestral fabric, yellowish-gray (5 Y 8/1), thin 

silty layers; bedding medium to indistinct and 

massive; bed of oncolites at 16 m and oolitic 

sandstone, 0.5 m thick, 21 m below top of 

unit; silty laminae and fenestral fabric present 

in upper 8 m.................................................... 60

Incomplete thickness of Clifside Limestone 60

Section 5

Reference section of the Dunderberg Shale and partial section of the 

Notch Peak Formation, northern Goshute Mountains. Section located 

along the crest of the mountain range in E % sec. 32, T. 32 N., R. 68 E., 

Lion Spring VVz-minute quadrangle, Nevada (fig. 12). Measured in August 

1989.

Notch Peak Formation (Upper Cambrian and Lower

Ordovician) (incomplete): Meters 

16. Lime mudstone, medium-gray (N5), with minor 

dusky yellow (5 Y 6/4) silty mottles 

(ichnofabric 3); bedding 40 cm thick or less; 

top of major vertical cliff................................ 150

15. Lime mudstone to packstone, medium-gray 

(N5), with dusky yellow (5 Y 6/4) silty mottles 

(ichnofabric 3); platy and thin bedded, 5-10 

cm thick in most of section; bedding planes 

are separated by silty layers; contains sparse 

trilobites and inarticulate brachiopods; basal 

meter contains Taenicephalusl', Billingsella! 

sp., Angulotretdl sp. (Taenicephalus 

Assemblage-zone)........................................... 90

14. Covered interval ............................................... 11

13. Lime mudstone, medium-gray (N5), with dusky 

yellow (5 Y 6/4) silty mottles (ichnofabric 

3); bedded, 5-8 cm thick................................. 2

12. Covered interval............................................... 24

II. Lime mudstone to packstone, light-gray (N7), 

completely recrystallized; silty mottles moderate red (5 R 5/4) and dusky yellow (5 Y 6/4) 

(ichnofabric 2); mottled layers 0.5-2 cm apart; 

beds 70 cm thick, separated by 20 cm of medium-dark-gray (N4) thin-bedded lime mudstone, 

some of which is recrystallized into calcite 

(white-band appearance); cliff-former............ 21

10. Covered interval ............................................... 27

Notch Peak Formation (Upper Cambrian and Lower

Ordovician) (incomplete): Continued Meters 

9. Lime mudstone to packstone, medium-gray (N5), 

with dark-yellowish-orange (10 YR 6/6) and 

yellowish-gray (5 Y 8/1) silty mottles 

(ichnofabric 3); bedding 15-30 cm thick; 

forms a low cliff.............................................. 6

Incomplete thickness of Notch Peak

Formation........................................... 331

Conformable contact.

Dunderberg Shale (Upper Cambrian):

8. Shale, light-olive-gray (5 Y 6/1); fissile, siliceous, 

with a few 10-cm-thick limestone layers; forms 

slopes, mostly covered.................................... 15

7. Wackestone to packstone, medium-gray (N5) to 

light-gray (N7); interbedded with calcareous 

siltstone, yellowish-gray (5 Y 8/1); forms small 

cliffs on ridge crest......................................... 18

6. Silty limestone, medium-gray (N5); and thinly 

interbedded calcareous siltstone, dark-yellowish-orange (10 YR 6/6)................................... 6

5. Lime mudstone to packstone, medium-gray (N5); 

thin- to medium-bedded, nodular; dark-yellowish-orange (5 YR 6/6) silty mottles 

(ichnofabric 3); trilobite packstone hi basal 

meter contains Irvingella angustilimbata 

Kobayashi, Housia cf. H. varro (Walcott), 

Sigmocheilus flabellifer (Hall and Whitfield), 

Homagnostus tumidosus (Hall and Whitfield), 

Pseudagnostus sp., and Kinbladia sp. (lower 

Ehirtia Assemblage-zone).............................. 6

4. Shale, light-olive-gray (5 Y 6/1) to dark-gray 

(N3); fissile, siliceous; interbedded with medium-gray (N5) lime mudstone beds as thick as 

1 m; yellowish-gray (5 Y 8/1) silty mottles 

(ichnofabric 2) present in limestone beds ....... 27

3. Lime mudstone, medium-gray (N5), with grayishorange (10 YR 7/4) silty mottles (ichnofabric 

2); bedding 10-20 cm thick; shale float near 

top; poorly exposed; slope former .................. 35

2. Silty limestone, medium-dark-gray (N4); silts 

moderate yellowish brown (10 YR 5/4) and 

dark yellowish orange (10 YR 6/6); beds 

undulose to nodular; siltstone; thin bedded; 

bedding 1-6 cm thick; trilobites include 

Dunderbergia rdtida (Hall and Whitfield), 

Aphelotoxon punctata Palmer, Homagnostus 

tumidosus (Hall and Whitfield), and Pseudagnostus sp. (Dunderbergia Assemblage-zone); 

forms small cliffs and benches along ridge 

crest................................................................. 30

1. Covered interval; float composed of mediumdark-gray (N4) platy silty limestone and darkgray (N3) to black (Nl) shale; silty beds moderate yellowish brown (10 YR 5/4) and dark 

yellowish orange (10 YR 6/6); trilobite packstone in basal meter contains Prehousia indenta 

Palmer and Pseudagnostus sp. (Prehousia Assemblage-zone); collection 12 m above base

38 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Dunderberg Shale (Upper Cambrian): Continued Meters 

contains Dicanthopyge quadrata Palmer, 

Olenaspella regularis Palmer, Listroat sp., 

Pseudagnostus sp., undetermined small olenid, 

Angulotreta sp. (Dicanthopyge Assemblagezone)............................................................... 38

Total thickness of Dunderberg Shale ...... 175

Conformable contact.

Goshute Limestone (Upper Cambrian) (not measured)

Section 6

Type section of the Oasis Formation and reference sections of the Morgan 

Pass Formation, Decoy Limestone, Shafter Formation, and Dunderberg 

Shale, Toano Range. Section located in NW'/ sec. 33, T. 35 N., R. 68 E., 

on ridge between Silver Zone Basin and "Proctor" Peak (7,602 ft), West 

Morris Basin 7%-minute quadrangle, Nevada (fig. 14). Measured in June 

1985.

Notch Peak Formation (Upper Cambrian and Lower 

Ordovician) (not measured)

Conformable contact. Meters 

Dunderberg Shale (Upper Cambrian):

22. Lime mudstone to wackestone, medium-gray 

(N5), platy to nodular, thin bedded, with almost 

50 percent silt in a variety of colors, including 

pale red (5 R 6/2), light brown (5 YR 6/4), 

and yellowish gray (5 Y 8/1); inarticulate 

brachiopods common on some bedding planes; 

Housia, Homagnostus, Pseudagnostus, and 

Elvinial in nodular carbonate ......................... 24

21. Shale, pale-olive (10 Y 6/2), fissile, siliceous, 

with rare trilobites including Housia; mostly 

covered; forms slopes ..................................... 20

20. Wackestone to packstone, medium-gray (N5) 

to light-gray (N7); interbedded with dusky 

yellow (5 Y 6/4) siltstone; crinoid columnals 

common, recrystallized................................... 10

19. Shale and siltstone, greenish-gray (5 G 6/1); 

weathers pale olive (10 Y 6/2); finely laminated to medium bedded................................... 15

18. Lime mudstone to wackestone, medium-gray 

(N5), thin-bedded to nodular, grayish-orange 

(10 YR 7/4) silty mottles (ichnofabric 3); palebrown (5 YR 5/2) to light-olive-gray (5 Y 

5/2) shaly interbeds......................................... 10

17. Shale, dark-gray (N3) to black (Ml); weathers 

light gray (N7); interbedded with medium-darkgray (N4) lime mudstone beds as thick as 

1 m; partly covered......................................... 35

16. Lime mudstone to wackestone, medium-gray 

(N5), with grayish-orange (10 YR 7/4) silty 

laminae; trilobite hash on bedding surfaces, 

including Dunderbergia sp ............................. 12

15. Shale, dark-gray (N3) to black (Nl); weathers 

light gray (N7); interbedded with medium-darkgray (N4) lime mudstone ................................ 15

14. Wackestone to grainstone, medium-dark-gray 

(N4); weathers brownish gray (5 YR 4/1); inDunderberg Shale (Upper Cambrian): Continued Meters 

distinct, undulose bedding surfaces occasionally covered with inarticulate brachiopods ..... £ 

Total thickness of Dunderberg Shale ...... 150

Conformable contact.

Oasis Formation (Upper Cambrian):

13. Lime mudstone to wackestone, medium-lightgray (N6); and light-gray (N7) dolomite, with 

yellowish-gray (5 Y 8/1) silty mottles 

(ichnofabric 2 and 3); partially recrystallized; 

weathers blocky and forms a moderate cliff... 60

12. Calcareous siltstone to silty wackestone, lightbrown (5 YR 5/5) to moderate-brown (5 YR 

4/4); beds 1-10 cm thick; weathers platy and 

forms slope ..................................................... 10

11. Wackestone to grainstone, medium-light-gray 

(N6); and light-gray (N7) dolomite; fenestral 

and cryptalgalaminite facies; minor silty 

mottles (ichnofabric 4 and 5) and oolitic 

grainstone, partially recrystallized.................. 65

10. Packstone, light-gray (N7), bioclastic with lightbrown (5 YR 5/6) silty partings; fauna of the 

upper Cedaria or lower Crepicephalus Assemblage-zones, including Meteoraspis cf. 

M. metra ......................................................... 3

9. Wackestone to grainstone, medium-light-gray 

(N6) to light-gray (N7); fenestral, stromatolitic, 

and cryptalgalaminite facies. Minor silty 

mottles (ichnofabric 4 and 5) and oolitic 

grainstone, partially recrystallized.................. 7

Total thickness of Oasis Formation......... 145

Conformable contact.

Shafter Formation (Middle and Upper Cambrian):

8. Lime mudstone to wackestone, medium-dark-gray 

(N4); moderate-yellowish-brown (10 YR 5/4) 

silty layers decreasing upward; poorly 

exposed........................................................... 13

7. Lime mudstone, dark-gray (N4); and grayishorange (10 YR 7/4), thin-to medium-bedded 

calcareous siltstone; bedding undulose to 

laminated; horizontal traces (ichnofabric 2) in 

thicker bedded unit at 19 m above base.......... 57

6. Covered interval; platy silty limestone float....... 20

5. Lime mudstone to wackestone, medium-dark-gray 

(N4), with grayish-orange (10 YR 7/4) to darkyellowish-orange (10 YR 6/6) silty laminae; 

weathers platy; trilobites and brachiopods 

common on some bedding surfaces, including 

Bolaspidellal, Cedarial, Baltagnostus, and 

Acmarhachis?; partly covered; forms slopes .. 50

4. Lime mudstone to wackestone, medium-dark-gray 

(N4) to medium-gray (N5); moderate-brown 

(5 YR 4/4) silty laminae with discrete mottles 

(ichnofabric 2); forms low, fairly continuous 

outcrop............................................................ 10

Total thickness of Shafter Formation...... 150

Conformable contact.

Measured Sections 39
Decoy Limestone (Middle Cambrian): Meters 

3. Dolomite and dolomitic limestone, medium-gray 

(N5) to very light gray (N8); very pale orange 

(10 YR 8/2) silty layers; forms a prominent 

light-gray cliff between slope-forming units... 60 

Total thickness of Decoy Formation....... 60

Conformable contact.

Morgan Pass Formation (Middle Cambrian):

2. Wackestone to grainstone, medium-dark-gray 

(N4) to medium-light-gray (N6), with grayishorange (10 YR 7/4) silty layers and mottles 

(ichnofabric 2 and 3); greenish-gray (5 GY 

6/1) to pale-olive (10 Y 6/2), fissile shale 

interbeds; flat-pebble conglomerates and oolitic 

layers containing oncolites and stromatolites 

present; largely covered; forms slopes............ 120

1. Lime mudstone to wackestone, medium-dark-gray 

(N4) to medium-light-gray (N6), with prominent grayish-orange (10 YR 7/4) silty partings. 

Weathering along silty partings 1-10 cm in 

thickness; Bolaspidella cf. B. wellsvillensis 

(Bolaspidella Assemblage-zone) .................... 5

Total thickness of Morgan Pass

Formation........................................... 125

Conformable contact.

Clifside Limestone (not measured):

Packstone to oolitic grainstone, medium-gray (N5) 

to medium-light-gray (N6), with thin, lightgray (N7) silty partings and mottles (ichnofabric 2 and 3); fenestral lime mudstone to 

wackestone, medium-dark-gray (N4) to 

medium-gray (N5), with beds of oncolites and 

cryptalgalaminites; massive texture; forms 

ridges.

Section 7

Reference section for the middle and upper parts of the Clifside 

Limestone, Toano Range. Section located in NW Vt sec. 28, T. 35 N., R. 

68 E., Silver Zone Pass 714-minute quadrangle, Nevada (fig. 14). 

Measured in June 1988.

Morgan Pass Formation (Middle Cambrian) (not 

measured)

Conformable contact. Meters 

Clifside Limestone (Middle Cambrian): 

Upper limestone member:

7. Dolomite, white (N9) to very light gray (N8); 

highly altered, primary sedimentary features 

obliterated; upper 20 m less altered; undulose 

silty lime mudstone alternating with very light 

gray (N8) cryptalgalaminites; upper member 

less altered to the south and composed entirely 

of alternating medium-gray (N5) lime mudstone, silty lime mudstone, and cryptalgalaminites...................................................... 100

Total thickness of upper limestone

member.............................................. 100

Silty limestone and shale member: Meters

6. Lime mudstone to wackestone, medium-lightgray (N6) to light-gray (N7); thin grayishorange (10 YR 7/4), silty undulose layers 

alternating with silty mottled (ichnofabric 2) 

Umestone......................................................... 25

5. Lime mudstone to wackestone, medium-lightgray (N6) to light-gray (N7), with grayish-orange (10 YR 7/4) silty layers as thick as 5 cm. 

Bedding is generally parallel to laminated, although nodular lime mudstone is present within 

the thicker silty beds. Unit weathers platy and 

rubbly; contains numerous inarticulate 

linguloid brachiopods and a few silicified 

marjumid trilobites. Unit has numerous calcitefilled fractures and a prominent calcite bed 

about 21 m above the base, although no faulting 

or offset is apparent........................................ 30

4. Lime mudstone to wackestone, medium-lightgray (N6) to light-gray (N7), with grayish-orange (10 YR 7/4) thin silty layers and 

mottles (ichnofabric 2).................................... 40

3. Dolomite, white (N9) to very light gray (N8); 

highly altered and bleached. Primary sedimentary features are largely obliterated; highly 

fractured throughout....................................... 35

2. Lime mudstone to oolitic grainstone, mediumlight-gray (N6) to light-gray (N7), with grayishorange (10 YR 7/4) to dark-yellowish-orange 

(10 YR 6/6) silty layers; parallel bedded to 

undulose, thin to medium bedded. At 9-9.5 m, 

silt locally weathers light red (5 R 6/6) to 

moderate red (5 R 5/4); at 22-35 m, silty limestone becomes thinner bedded and platier, with 

small horizontal burrows on bedding surfaces; 

at 34-34.5 m, light-gray (N7) to medium-lightgray (N6) oolitic grainstone overlain by 

oncolitic wackestone to packstone; at 45 m, 

25-cm-thick oolitic grainstone; at 46.5-47.5 m, 

oolitic grainstone; at 56-57 m, silt becomes 

mottled (ichnofabric 3). Above 57 m, thin 

silty layers become light gray (N7)................. 70

1. Calcareous siltstone, silty limestone, and shale, 

light brown (5 YR 5/6), micaceous sheen; 

forms rubbly slopes; poorly exposed .............. 5

Total thickness of silty Umestone and

shale member..................................... 205

Lower limestone member (not measured):

Lime mudstone to oolitic grainstone, medium-gray 

(N5) to medium-light-gray (N6); light-gray 

(N7), undulose, dolomitic, and silty laminae. 

Yellowish-gray (5 Y 8/1) dolomitic cryptalgalaminites, fenestral lime mudstone, oncolitic 

packstone, and oolitic grainstone beds are 

present. Clifside is recrystallized, and pure 

limestones are hydrothermally altered to 

coarsely crystalline dolomite owing to proximity of Silver Zone Pass pluton.

40 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Section 8

Reference section of the Notch Peak Formation, Toano Range. Section 

located in NW % sec. 33, T. 34 N., R. 68 E.,West Morris Basin TVi-minute 

quadrangle, Nevada (fig. 14). Measured in June 1986.

Pogonip Group (Lower Ordovician) (not measured)

Conformable contact. Meters 

Notch Peak Formation (Upper Cambrian and Lower

Ordovician):

5. Lime mudstone to wackestone, medium-gray (N5) 

to medium-dark-gray (N4); laminated, grayishorange (10 YR 7/4) silty partings and black 

(Nl) nodular chert; medium bedded, with some 

recrystallized very light gray (N8) dolomitic 

layers. A 20-cm-thick bed containing softsediment folding, with an east-west axis, crops 

out 5 m above the base. Vertical silty burrows 

(ichnofabric 3) are present 3.5-4 m above the 

base; forms ridges........................................... 20

4. Limestone, light-gray (N7), recrystallized, containing black (Nl) nodular chert in upper 5 m. 

Occasional 1-m-high thrombolites are present; 

forms rubbly slope; largely covered................ 45

3. lime mudstone to wackestone, medium-gray (N5) 

to medium-dark-gray (N4), with thin, diffuse, 

grayish-orange (10 YR 7/4) silty laminae. 

Upper 3 m contain black (Nl) nodular chert as 

thick as 5 cm. Yellowish-gray (5 Y 8/1), 

mottled silty layers and burrows, 1 cm in diameter (ichnofabric 2), present near middle; 

largely cliff forming........................................ 50

2. Lime mudstone to wackestone, medium-gray (N5) 

to medium-dark-gray (N4); largely recrystallized, dolomitic, prominent silty layers present; 

layers of black (Nl) nodular chert throughout; 

forms slopes, with extensive covered intervals. 

Locally faulted................................................ 250

1. Lime mudstone to wackestone, medium-gray (N5) 

to medium-dark-gray (N4); grayish-orange (10 

YR 7/4) silty laminae; locally mottled, with 

horizontal burrows (ichnofabric 2); occasional 

beds of medium-dark-gray (N4) to black (Nl) 

nodular chert as thick as 3 cm. Several lightgray (N7) recrystallized beds as thick as 25 

cm give this unit a faintly banded 

appearance...................................................... 85

Total thickness of Notch Peak Formation 450

Conformable contact. 

Dunderberg Shale (not measured)

Section 9

Incomplete reference section of Toano Limestone and Killian Springs 

Formation, central Silver Island Mountains. Section located in SW 1A NE 

Vi sec. 9, and SW'/« SE V* sec. 4, T. 1 N., R. 18 W., Tetdaff Peak TAminute quadrangle, Utah (fig. 9). Measured in July 1983.

Clifside Limestone (Middle Cambrian)(not measured) 

Conformable contact.

Toano Limestone (Middle Cambrian) (incomplete): Meters 

18. Lime mudstone, medium-gray (N5) to dark-gray 

(N3), silty, laminated. Silicified agnostoids, 

including Ptychagnostus atavus, present 80 m 

below top. Silicified trilobites, including 

Ptychagnostus, Toniunella, and Zacanthoides, 

present 80 m above base ................................. 253

17. Covered interval ............................................... 7

16. Lime mudstone, medium-gray (N5) to dark-gray

(N3), laminated............................................... 13

15. Covered interval............................................... 5

14. Lime mudstone, medium-gray (N5) to dark-gray 

(N3), with finely laminated, dark-yellowishorange (10 YR 6/6), calcareous phyllitic 

siltstone........................................................... 37

13. Covered interval............................................... 11

12. Lime mudstone, medium-gray (N5) to darkgray (N3), laminated....................................... 4

11. Covered interval............................................... 31

10. Phyllitic siltstone, calcareous; and laminated to 

thin-bedded lime mudstone; dark gray (N3); 

weathers medium light gray (N6), with darkyellowish-orange (10 YR 6/6) iron staining; 

pyrite throughout............................................ 14

Incomplete thickness of Toano Limestone ................................................... 375

A prominent alluvial strike valley separates the upper siliciclastic 

f acies of the Killian Springs Formation from the Toano Limestone, making accurate thickness measurements impossible. 

Approximately 450 m of the Toano Limestone covered.

Killian Springs Formation (Lower and Middle Cambrian) (incomplete): 

Light-brown quartz sandstone unit:

9. Quartz sandstone, calcareous, very light gray (N8) 

to light-gray (N7), with light-brown (5 YR 

5/6) to grayish-brown (5 YR 3/2) iron staining 

and Liesegang banding. Calcareous sandstone 

has rudimentary bedding averaging 10-15 cm 

thick and is characterized by a uniform grain 

size and lack of primary bedding features; 

cavernous weathering; small pyrite cubes 

present, becoming abundant near sillier layers. 

Top is faulted against the Prospect Mountain 

Quartzite, which is riddled by numerous milky 

white quartz veins...........................................

Incomplete thickness of light-4jrown 

quartz sandstone unit..........................

35 

.3S

Phyllitic siltstone and argillaceous limestone unit:

8. Graphitic siltstone and phyllite, medium-darkgray (N5), finely laminated. Contact with overlying sandstone is sharp; interbeds of very pale 

orange (10 YR 8/2) to light-brown (5 YR 5/6) 

sandstone in the lowermost 8 m; occasional 

sponge spicules throughout; cubic pyrite as wide 

as 2 cm throughout; locally covered; best exposed on small ridge along southern border 

of section 4 ..................................................... 11

Measured Sections 41
Phyllitic siltstone and argillaceous limestone unit: 

Continued Meters 

7. Argillaceous limestone, medium-gray (N5) to 

dark-gray (N3); and finely laminated siltstone 

and silty mudstone; black (Nl) to dark-gray 

(N3) phyllitic siltstone interbeds; sponge spicules present in uppermost 5 m; only intermittently exposed in channel washes on talus 

slopes.............................................................. 20

6. Covered interval ................................................. 17

5. Siltstone and silty mudstone, dark-gray (N3) 

to light-gray (N7), noncalcareous and fissile 

to calcareous and nonfissile, grading into 

thin-bedded lime mudstone at top; pyrite 

throughout....................................................... 15

4. Covered interval................................................. 12

3. Siltstone, phyllitic, medium-dark-gray (N4), 

noncalcareous fissile to calcareous and nonfissile; occasional sponge spicules and rare, round 

granules of phosphate present; thin (10-30 cm), 

dark-gray (N3) granule sandstone interbeds; has 

a metalliferous sheen, probably due to mica 

and pyrite........................................................ 15

Total thickness of phyllitic siltstone and

argillaceous limestone unit................. 90

Quartzofeldspathic granule sandstone and phyllitic

siltstone unit:

2. Quartz sandstone, yellowish-gray (5 Y 8/1) with 

dusky brown (5 YR 2/2) staining, moderately 

to poorly sorted, medium- to coarse-grained, 

locally conglomeratic, weakly parallel-laminated; massive weathering; forms layers 5 7 

m thick; sharp tabular to channeled contact at 

base; ledge former. Grayish-black (N2), lightgray (N7) to white (N9) weathering phyllitic 

shale and siltstone form intervals 1.5-9 m thick 

between sandstone layers; sooty appearance 

on weathered surfaces; recessive; mostly 

covered........................................................... 34

1. Phyllitic shale and siltstone, grayish-black (N2); 

weathers light gray (N7) to white (N9); highly 

stained, moderate red (5 R 4/6) to blackish red 

(5 R 2/2); sooty appearance on weathered 

surfaces; beds 7-60 cm thick; discontinuous 

beds of quartz-granule conglomerate, 5-10 cm 

thick, with load casts at base; small pyrite 

cubes throughout; recessive weathering.......... 6

Total thickness of quartzofeldspathic

sandstone and phyllitic siltstone unit.. 40 

Incomplete thickness of Killian Springs

Formation........................................... 165

Sharp conformable contact. 

Prospect Mountain Quartzite (not measured): 

Quartzite, white (N9) to very light gray (N8), with a 

dusky yellowish-brown (10 YR 2/2) appearance due 

to iron staining; medium- to coarse-grained, conglomeratic channel deposits present; medium to

Prospect Mountain Quartzite (not measured): 

Continued Meters 

thick crossbeds present in tabular sets; occasional 

thin silty beds containing ubiquitous pyrite cubes; 

forms prominent cliffs.

Section 10

Reference section of the Big Horse Limestone, Candland Formation, 

Johns Wash Limestone, Corset Spring Shale, and Notch Peak Formation, 

central Silver Island Mountains. Section located in NW VJ unsurveyed sec. 

29, SW Y* unsurveyed sec. 20, ME 1A unsurveyed sec. 19, T. 2 N., R. 17 

W., Graham Peak TVi-minute quadrangle, Utah (fig. 17). Measured in May 

1986.

Garden City Formation (Lower Qrdovician) (not 

measured)

Conformable contact. Meters 

Notch Peak Formation (Upper Cambrian and Lower 

Ordovician):

11. Limestone, medium-dark-gray (N4) to dark-gray 

(N3), and medium-gray (N5) to medium-bluish-gray (5 B 5/1) dolomite, with dark-yellowish-brown (10 YR 4/2) to brownish-black (5 

YR 2/1) chert nodules common in lower half; 

indistinctly bedded, possibly owing to bioturbation and lack of silt; a 15-cm-thick, lightbluish-gray (5 B 7/1) quartz sandstone bed, 

weathering moderate brown (5 YR 4/4), present 60 m above base; stromatolitic and oolitic 

beds near middle; forms inaccessible vertical 

cliffs; thickness estimated.............................. 400

10. Lime mudstone to wackestone, medium-gray 

(N5), with moderate-brown (5 YR 4/4) silty 

mottles (ichnofabric 2 and 3); occasional chert 

nodules near top of unit; abundant inarticulate 

brachiopods on some bedding planes; has an 

alternating light- and dark-gray banded appearance owing to white (N9) to very light 

gray (N8) marker layers present at 66.5-68 m, 

62.5-65.5 m, 48^8.5 m, 40-40.5 m, 36.5-37 

m, 18-18.3 m, 16.5-17 m, 14.5-15 m, and 

0.6-1 m above base; forms ledges and cliffs .. 75 

9. Lime mudstone to wackestone, medium-dark-gray 

(N4), with moderate-brown (5 YR 4/4) to lightbrown (5 YR 6/4), undulose silty beds about 2 

cm thick (ichnofabric 3); inarticulate brachiopods on some silty surfaces. Robison and 

Palmer (1968) reported a Taenicephalus Assemblage-zone fauna (5984-CO); forms 

ledges.............................................................. 25

Estimated thickness of Notch Peak Formation ................................................ 500

Conformable contact.

Corset Spring Shale (Upper Cambrian):

8. Limestone, recrystallized, pinkish-gray (5 YR 

8/1), stylolitic; alternating layers, 0.3-0.5 m 

thick, of pale-brown (5 YR 5/2) to moderatebrown (5 YR 4/4) wackestone and dusky brown

42 Cambrian Stratigraphy of the Wendover Area, Utah and Nevada
Corset Spring Shale (Upper Cambrian): Continued Meters 

(5 YR 2/2) siltstone, 15-25 cm thick; occasional 

medium-dark-gray (N4), less recrystallized 

limestone beds; calcareous, moderate-brown (5 

YR 4/4) shale and siltstone, and thin-bedded 

(10 cm), light-olive-gray (5 Y 6/1) silty limestone in basal meter. Robison and Palmer 

(1968) reported an Elvinia Assemblage-zone 

fauna (5985-CO); forms prominent ledges ..... 16 

Total thickness of Corset Spring Shale ... 16

Conformable contact.

Johns Wash Limestone (Upper Cambrian):

7. Dolomite and limestone, coarsely recrystallized, 

light-gray (N7) to yellowish-gray (5 Y 8/1). 

Uppermost 8 m are medium-gray (N5) to 

pinkish-gray (5 YR 8/1) limestone, somewhat 

less altered; cliff-forming white band at 25- 

57 m. Slope-forming, very light gray (N8) to 

white (N9) dolomitic limestone, with occasional pockets of dark-gray (N3) limestone at 

10-25 m above the base; moderate-brown (5 

YR 4/4) siltstone concentrated in stylolites; 

light-bluish-gray (5 B 7/1) dolomite in lowermost 10 m; forms cliffs................................... 65

6. Silty lime mudstone to wackestone, medium-darkgray (N4), with moderate-brown (5 YR 4/4) to 

dark-yellowish-brown (10 YR 4/2) siltstone 

containing discrete mottles (ichnof abric 2 and 

3) in beds about 5 cm apart. Upper half contains several oncolite and thin limestone ripup beds; forms ledges in lower half and 

cliffs in upper half........................................... 15

Total thickness of Johns Wash Limestone 80

Conformable contact.

Candland Formation (Upper Cambrian):

5. Shale, black (Nl); weathers light olive gray (5 Y 

6/1) and grayish orange pink (10 R 8/2); laminated; contains nodular limestone; thin 

interbeds of medium-dark-gray (N4) argillaceous limestone throughout; forms slopes ... 82

Candland Formation (Upper Cambrian): Continued Meters 

4. Wackestone to packstone, medium-dark-gray 

(N4); and wispy light-brown (5 YR 5/6) to 

moderate-yellowish-brown (5 YR 5/4) siltstone; lowest beds covered with inarticulate 

brachiopods. Robison and Palmer (1968) reported a Dicanthopyge Assemblage-zone fauna 

(5986-CO); forms slopes ................................ 3

Total thickness of Candland Formation.. 85

Conformable contact.

Big Horse Limestone (Upper Cambrian):

3. Lime mudstone to wackestone, medium-dark-gray 

(N4) to medium-gray (N5), generally recrystallized and dolomitic above 60 m; recrystallized beds light gray (N7) to bluish-white (5 B 

9/1); silty mottles (ichnofabric 3 and 4) and 

domal stromatolites common in basal 30 m; 

moderate-red (5 R 4/6) quartz sandstone beds 

35 m above base. Robison and Palmer (1968) 

reported a Crepicephalus Assemblage-zone 

fauna (5987-CO); forms upper two-thirds of 

a light-gray cliff.............................................. 175

Total thickness of Big Horse Limestone. 175

Conformable contact.

Lamb Dolomite (Upper Cambrian):

2. Dolomite, recrystallized; uppermost 50 m pinkishgray (5 YR 8/1); lowermost 60 m medium gray 

(N5) to medium bluish gray (5 B 5/1); discrete 

silty mottling (ichnofabric 2) and faint lowangle crossbedding; forms lower one-third of 

a light-gray cliff.............................................. 110

1. Wackestone to packstone, medium-dark-gray 

(N4), fresh; weathers medium light gray (N6); 

mottled dark-yellowish-orange (10 YR 6/6) to 

light-brown (5 YR 5/6) dolomitic silt 

(ichnofabric 4 and 5). Robison and Palmer 

(1968) reported a Cedaria or Crepicephalus 

Assemblage-zone fauna (5988-CO); base of 

section in alluvium.......................................... 20

Incomplete thickness of Lamb Dolomite 130

Measured Sections 43

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