The Auld Lang Syne Group, 

of Late Triassic and 

Jurassic(P) Age, 

North-Central Nevada

GEOLOGICAL SURVEY BULLETIN 1394-E

.

The Auld Lang Syne Group, 

of Late Triassic and 

Jurassic(P) Age, 

North-Central Nevada

By D. B. BURKE and N. J. SILBERLING

CONTRIBUTIONS TO STRATIGRAPHY

GEOLOGICAL SURVEY BULLETIN 1394-E

Defines stratigraphic nomenclature for a 

thick sequence of lower Mesozoic rocks 

in north-central Nevada

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1973
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 73-600257

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

Washington, D. C. 20402 - Price 35 cents (paper cover) 

Stock Number 2401-02431
CONTENTS

Page

Abstract...................................................................................................................... El

Introduction ......................................................................... .................................. 1

Stratigraphic description ........................................................................................ 7

Type area and section ..................................._....................................,........... 7

Reference area and section ............................................................................ 8

Age .......................................................................................................................... 9

Regional extent ........................................................................................................ 10

Stratigraphic and structural setting.............................................................. 10

Strata north and west of the type area....................................................... 10

Strata south and east of the type area........................................................... 11

Paleogeographic interpretation ................. .........._............... .............................. 13

References cited........................................................................................................ 14

ILLUSTRATIONS

Page

FIGURE 1. Index map of north-central Nevada showing the type and

reference areas of the Auld Long Syne Group.......................... E2

2. Generalized geologic maps of the type and reference

areas of the Auld Lang Syne Group........................................... 4

3. Time-stratigraphic correlation of Upper Triassic and

Lower Jurassic rock units in north-central Nevada ................ 6

TABLE

Page

TABLE 1. Type localities of the formations of the Auld Lang Syne Group E3

in

CONTRIBUTIONS TO STRATIGRAPHY

THE AULD LANG SYNE GROUP,

OF LATE TRIASSIC AND JURASSIC(?) AGE,

NORTH-CENTRAL NEVADA

By D. B. BURKE and N. J. SILBERLING

ABSTRACT

As herein defined, the Upper Triassic and Jurassic (?) Auld Lang Syne Group 

comprises the previously defined Grass Valley, Osobb, Dun Glen, Winnemucca, 

O'Neill, Raspberry, Singas, Andorno, and Mullinix Formations. The group is 

composed of as much as 25,000 feet of generally argillaceous and sandy strata 

that were derived from an eastern source area and that were seemingly 

deposited in a shallow marine, deltaic environment.

INTRODUCTION

The name Auld Lang Syne Group is hereby proposed for a very 

thick, lithologically uniform sequence of formations in north-central 

Nevada (figs. 1, 2, and 3). The Triassic Grass Valley, Osobb, Dun 

Glen, Winnemucca, O'Neill, Raspberry, Singas, and Andorno Formations and the Triassic and Jurassic (?) Mullinix Formation constitute 

parts of an apparently continuous succession of variably metamorphosed, interlensing, argillaceous and sandy strata, with subordinate 

amounts of limestone and dolomite. The lithologic character of this 

sequence stands in marked contrast to that of the two older Mesozoic 

groups exposed in the region the volcanic and tuffaceous clastic 

Koipato Group of Early Triassic age (Silberling, 1973) and the predominantly carbonate and coarse clastic Star Peak Group of Early 

to Late Triassic age (Silberling and Wallace, 1969). The strata 

included here in the Auld Lang Syne Group overlie with sharp contact 

the strata of the Star Peak Group and is unconformably overlain by 

Tertiary volcanic rocks. The type and reference sections of the Auld 

Lang Syne Group have a total thickness of about 25,000 feet. This 

new name is proposed in order to express the uniform lithologic character of the formations within this part of the Mesozoic section in 

north-central Nevada and to set these formations apart, as a single 

stratigraphic entity, from the groups that form the lower parts of the 

section.

El
E2 CONTRIBUTIONS TO STRATIGRAPHY

118° 117°

OM,

~'~' *''J - __PERSH1NG COUNTY

CmJRCHirL COUNTY'"-. 

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FIGURE 1. Index map of north-central Nevada showing the type and reference 

areas of the Auld Lang Syne Group, location of columns in figure 3, and 

geographic features referred to in text.
AULD LANG SYNE GROUP, TRIASSIC AND JURASSIC (?) E3

In order to bring the definitions of the formations of the Auld Lang 

Syne Group into closer accord with the modern rules of stratigraphic 

nomenclature, the original "type localities" of the Grass Valley, 

Osobb, Dun Glen, Winnemucca, and Raspberry Formations (Ferguson and others, 1951b; Muller and others, 1951) are here redesignated 

as type areas. New type localities which are geographically more 

restricted than the old type areas are defined in table 1. In addition,

TABLE 1. Type localities of the formations of the Auld Lang Syne Group

Formation and Coordinates of type localities as

initial description designated in this report 15' quadrangle

Grass Valley Formation

(Muller and others, 1951) ..........Sees. 30, 31, and 32, T. 34 N.,

R. 37 E., and Sees. 24, 25,

and 36, T. 34 N., R. 36 E....Rose Creek.

Osobb Formation

(Muller and others, 1951) ..........Sec. 21, T. 25 N., R. 39 E......Cain Mountain.

Dun Glen Formation

(Muller and others, 1951) ..........Sec. 26, T. 34 N., R. 36 E......Rose Creek.

Winnemucca Formation

(Muller and others, 1951) ..........Sees. 4 and 5, T. 34 N., R.

38 E ......................................Winnemucca.

Raspberry Formation

(Ferguson and others, 1951b) ....Sees. 31,32, and 33, T. 34 N.,

R. 36 E ............................. Rose Creek.

O'Neill Formation

(Compton, 1960) ..........................Sees. 26 and 35, T. 41 N.,

R. 38 E ................................Paradise Valley.

Singas Formation

(Compton, 1960) ..........................Sees. 26 and 27, T. 41 N.,

R. 38 E ................................ Do.

Andorno Formation

(Compton, 1960) ..........................Sees. 15,16, and 17, T. 41 N.,

R. 38 E ................................ Do.

Mullinix Formation

(Compton, 1960) ..........................Sees. 17 and 20, T. 43 N.,

______________________R. 39 E ................................Hinkey Summit.

the "type areas" of the O'Neill, Singas, Andorno, and Mullinix Formations (Compton, 1960) are here redesignated as type localities and 

are given geographic coordinates in table 1.

Acknowledgments. Field studies by the 1971 Stanford University 

summer field geology class (under our direction) have supplied much 

of the information in this report about the geology of the northern 

East Range. Some of the field investigations that have supplied information incorporated here were supported by grants GA-1398 and GA19424 to Stanford University from the National Science Foundation.
E4 CONTRIBUTIONS TO STRATIGRAPHY

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R.37E. 117° 45' 117°40' R.38E. R. 39 E.

SMILES

4 KILOMETERS

Contact

? 

Fault 

Queried where doubtful

Strike and dip of beds 

Not necessarily upright

Strike and dip of 

overturned beds

Strike of vertical beds

Trend and plunge of 

small folds

Anticline Syncline

Showing trace of axial

plane and plunge

tt

Overturned anticline

Showing trace of axial

plane and plunge

FIGURE 2. Generalized geologic maps of the type and reference areas of the Auld Lang Syne Group. B, Southern end of the Santa Rosa Range (reduced from 1:62,500 map in Compton, 1960).

v^

6

5P

I

I >3

M en
LOCATION OF COLUMNS

1 Southern Santa Rosa Range 

(reference area of Auld 

Lang Syne Group)

2 Krum Hills

3 Northern Sonoma Range

4 Northern East Range 

(type area of Auld 

Lang Syne Group)

5 Southern Humboldt Range

6 Northern Stillwater Range 

Southern Tobin Range

* Mullinix 

Formation

8 Northern Augusta Mountains

Raspberry 

Formation Unnamed qu 

/ite and mudstone formation * Sin gas Formation

innemucca 

Formation

Winnemucca 

Formation

Winnemucca 

Formation

« Winnemucce 

Formation Dun Glen 

Formation

Winnemucca 

Formation Dun Glen Formation Dun Glen Formation

Grass Velley 

Formation

Grass Valley 

Formation

Grass Valley 

Formation

Grass Valley 

Formation

* Osobb Formation Grass Valley Formation

* Cane Spring / / Formation *Natchez Pass Formation Natchez Pass Formation Natchez Pass Formation Natchez Pass Formation Natchez Pass Formation

FIGURE 3. Time-stratigraphic correlation of Upper Triassic and Lower Jurassic rock units in north-central Nevada. Names of rock 

units included in the Auld Lang Syne Group in boldface type; occurrence of age-diagnostic fossils indicated by arrows; lack of 

stratigraphic record indicated by diagonal ruling; type areas of units indicated by asterisks with names. Ages of all formation boundaries only approximate. See figure 1 for location of sections.
AULD LANG SYNE GROUP, TRIASSIC AND JURASSIC (?) E7

STRAT1GRAPHIC DESCRIPTION 

TYPE AREA AND SECTION

The type area of the Auld Lang Syne Group is in the northern East 

Range, southwest of Winnemucca (figs. 2A and 3). The type section 

is north of Auld Lang Syne Peak (sec. 12, T. 33 N., R. 36 E.; Dun 

Glen quadrangle), the source of the name, and it extends from sec. 32, 

T. 34 N., R. 37 E. to sec. 23 and 24, T. 34 N., R. 36 E. on the Rose 

Creek quadrangle. This section crosses exposures of typical Grass 

Valley Formation, typical Dun Glen Formation, and Winnemucca 

Formation (figs. 2A and 3). The type Raspberry Formation also 

crops out near this section and is included in the group. It is not, 

however, in stratigraphic sequence with the other formations.

The lower boundary of the Auld Lang Syne Group is a sharp, perhaps disconformable, contact between gray massive carbonate rocks 

of the Natchez Pass Formation the highest unit of the Star Peak 

Group (Silberling and Wallace, 1969) and the olive-gray noncalcareous argillite of the overlying Grass Valley Formation. This micaceous and thinly parted argillite is interstratified with thin-bedded 

units of fine-grained impure sandstone having a diversity of sedimentary structures. Linguloid ripple marks, ripple-drift crossbedding, 

load casts, and other sole marks are characteristic of these strata and 

of those with comparable lithology in overlying formations. In the 

higher part of the Grass Valley Formation, medium to thick interbeds 

of markedly lensoid cross-stratified feldspathic sandstone and several 

thick-bedded lenses of bioclastic limestone like those in the overlying 

Dun Glen Formation are interstratified with the pelitic rocks. The 

Grass Valley Formation is generally poorly exposed; but small tight 

folds common in the isolated outcrops indicate that the unit has been 

much deformed. The formation is at least 2,000 feet thick in the type 

area of the Auld Lang Syne Group; elsewhere in the northern part of 

the East Range; it is no more than 300 feet thick.

The Dun Glen Formation, which gradationally overlies the Grass 

Valley Formation, is composed of gray, very thick to thick-bedded 

limestone and dolomite with minor interbeds of sandstone and argillite similar to those of the Grass Valley Formation. The limestone 

is predominantly fine grained and contains whole or broken fossils of 

shallow-water marine invertebrates, including corals, spongiomorphs, 

echinoderms, mollusks, and brachiopods; subordinate interbeds of 

cross-stratified calcarenite also are present. Most of the dolomitic beds 

in the formation have fine-grained saccharoidal textures and are evidently secondary in origin. All these strata are characteristically 

lenticular, but the Dun Glen as a whole maintains a relatively constant thickness of about 600 feet throughout the East Range.
E8 CONTRIBUTIONS TO STRATIGRAPHY

The Winnemucca Formation includes a diversity of rock types gradationally overlying the carbonate rocks of the Dun Glen Formation. 

The upper boundary of the unit is an unconformity with Tertiary and 

Quaternary rocks both in the East Range and in its type area in the 

Sonoma Range. The younger Raspberry Formation is faulted against 

the Winnemucca in the East Range and in the Krum Hills north of 

the East Range. The Winnemucca Formation in the East Range consists of a laterally variable succession of thin- to thick-bedded siliceous and calcareous feldspathic sandstone and pale-colored laminate 

fine-grained clastic rocks. Gray thin to thick lenticular beds of Dun 

Glen-like limestone and dolomite occur throughout the Winnemucca; 

these beds constitute as much as 50 percent of the formation in its 

higher parts. The thickest section of the Winnemucca Formation that 

is exposed in the East Range is about 1,200 ft; the less complete section in the type area of the Auld Lang Syne Group is about half as 

thick.

In its type area in the northwestern part of the East Range, the 

Raspberry Formation is mainly composed of argillaceous rocks but 

has subordinate amounts of limestone in its lower part (according to 

Ferguson and others, 1951b). Intercalations of sandstone form only 

a minor part of the formation. In the East Range, where neither the 

base nor the top is exposed, a thickness of 3,000 feet was estimated by 

Ferguson, Muller, and Roberts (1951b). Farther north in the Krum 

Hills the strata assigned to the Raspberry Formation by Willden 

(1964) are believed to be at least 7,000 or 8,000 feet thick.

REFERENCE AREA AND SECTION

The south end of the Santa Rosa Range is designated the reference 

area of the Auld Lang Syne Group (figs. 2B and 3). The reference 

section in this area extends from sec. 6, T. 40 N., R. 39 E., to sec. 7, T. 

41 N., R. 38 E. and includes the Grass Valley, Winnemucca, O'Neill, 

Singas, Andorno, and Mullinix Formations. The lithologic character, 

stratigraphy, and structure of these rocks have been well described 

by Compton (1960) in his report on geology of the Santa Rosa Range 

and Bloody Run Hills. The O'Neill, Singas, Andorno, and Mullinix 

Formations were first defined by Compton; their type areas here 

redesignated type localities (table 1) are in and near the reference 

area of the Auld Lang Syne Group. The reference section follows the 

line of cross section B-B' on the map that accompanies Compton's 

report.

Both the Grass Valley and Winnemucca Formations are recognized 

in the metamorphosed strata of the Santa Rosa Range, but the Dun 

Glen Formation, which intervenes between these units in the East 

Range, is seemingly reduced to only isolated lenses of carbonate rock
AULD LANG SYNE GROUP, TRIASSIC AND JURASSIC (?) E9

in what has been mapped as Winnemucca Formation (Compton, 

1960). The overlying O'Neill, Singas, Andorno, and Mullinix Formations complete the Mesozoic sequence in the range, and they are 

uncomformably overlain by Tertiary volcanic rocks. These formations 

are predominantly composed of pelitic rocks with subordinate sandstone. The finer grained strata have been regionally metamorphosed 

to slate and phyllite, and the sandstone units to quartzite. Lensoid 

beds of carbonate rocks, now represented as fine-grained calcite or 

dolomite marble, are a variable but small fraction of the total rock 

volume. The contacts between these units are gradational, and the 

units are largely defined by changes in the proportions of different 

rock types. Compton mentions that the phyllite, quartzite, and minor 

clastic limestone of the Singas Formation are lithologically similar to 

much of the Raspberry Formation.

AGE

Very few age-diagnostic fossils have been found in the Auld Lang 

Syne Group (fig. 3), although shell debris is a major component of 

many limestone beds, and silicified wood fragments (and occasional 

large logs) occur in sandstone in the lower parts of the group.

In the Humboldt Range, the underlying Natchez Pass Formation 

in the upper part of the Star Peak Group is late Karnian (early Late 

Triassic) in age, and the uppermost Grass Valley Formation is early 

middle Norian (middle Late Triassic). The base of the Auld Lang 

Syne Group, therefore, approximately coincides with the KarnianNorian boundary (Silberling and Wallace, 1969).

Fragmentary ammonites from the type Dun Glen Formation are 

characteristic of the lower middle Norian Juvavites magnus Zone of 

Silberling and Tozer (1968). Ammonites from an unknown stratigraphic position in the type Raspberry Formation represent the 

Himavatites columbianus Zone of late middle Norian age, and the late 

Norian bivalve Monotis subcircularis occurs in rocks assigned to the 

Raspberry by Ferguson, Muller, and Roberts (1951b) in the Krum 

Hills. Deformed ammonites from the Winnemucca and Andorno Formations in the Santa Rosa Range, reported by Compton (1960), are 

too poorly preserved to warrant even a tentative age assignment (Silberling and Wallace, 1969, p. 16), but Monotis cf. M. subcircularis 

and the brachiopod Halorella sp. indicate a late Norian age for the 

Andorno. Considering the lack of fossils in the 5,000 feet or more of 

strata in the overlying Mullinix Formation and the apparently short 

duration of the Rhaetian Age (Silberling and Tozer, 1968), the Mullinix, and therefore the uppermost part of the Auld Lang Syne Group, 

may well include strata of Jurassic age.
E10 CONTRIBUTIONS TO STRATIGRAPHY

REGIONAL EXTENT 

STRATIGRAPHIC AND STRUCTURAL SETTING

Strata that can be assigned to the Auld Lang Syne Group crop out 

widely in north-central Nevada (figs. 1 and 3). Other strata, comparable in lithology and age but as yet little studied and unnamed, 

occur in stratigraphically isolated exposures throughout the northwestern part of the state.

Most of the present formational nomenclature in north-central 

Nevada was defined in the reports based on the initial reconnaissance 

mapping of the region (Ferguson and others, 1951a and b; Muller and 

others, 1951; Ferguson and others, 1952). The numerous Mesozoic 

formations were at that time separated into two distinct "facies," for 

it was believed that a thrust with tens of miles of displacement (the 

Tobin thrust) had juxtaposed two generally age-equivalent but lithologically distinct successions of lower Mesozoic strata along with 

upper Paleozoic rocks during Jurassic orogeny. Silberling and Roberts 

(1962) later questioned the magnitude of post-Triassic thrust faulting and suggested that juxtaposition of upper Paleozoic rocks occurred prior to Triassic deposition. Because the stratigraphic relation 

between the "lower-plate facies" and "upper-plate facies" was left in 

doubt, these successions were redefined as the "Winnemucca" and 

"Augusta sequences." Recent investigations have substantiated that 

there was an episode of large-scale thrust faulting in the earliest Triassic the Sonoma orogeny and have demonstrated that the diverse 

Mesozoic formations defined in the earlier reports are all essentially 

autochthonous and are far more laterally variable than had been 

realized (Burke, 1970; Silberling, 1973).

STRATA NORTH AND WEST OF THE TYPE AREA

In the Humboldt Range, strata that overlie massive carbonate 

rocks of the Natchez Pass Formation (the upper part of the Star Peak 

Group) have been assigned in part to formations that are here 

included in the Auld Lang Syne Group. The Grass Valley Formation 

is recognized in the northwestern and southern parts of the range, 

and the Dun Glen Formation and younger unnamed units overlie the 

Grass Valley in the southern part of the range (Silberling and Wallace, 1969). The Grass Valley is at least 2,000 feet thick. Stratigraphically continuous carbonate rocks that are assigned to the Dun Glen 

are generally only 100-150 feet thick, but discontinuous beds of Dun 

Glen-like carbonate rock occur in the two unnamed units stratigraphically above. These unnamed units consist of at least 2,000 feet of 

intensely deformed, poorly exposed strata. Silberling and Wallace 

(1969, p. 44) have pointed out that they are "lithologically similar,
AULD LANG SYNE GROUP, TRIASSIC AND JURASSIC (?) Ell

partly correlative, and genetically related to the Winnemucca Formation and Raspberry Formation." However, because the Winnemucca 

and Raspberry Formations in their type areas are "neither unique in 

lithologic composition nor bracketed by distinctive stratigraphic 

boundaries," lithologic correlation of the unnamed units and the two 

formations is not possible. The unnamed strata in the Humboldt 

Range include the variety of rock types characteristic of the Auld 

Lang Syne Group in its type and reference sections; discontinuous 

beds of argillite, ripple-marked or cross-stratified siltstone and sandstone, and impure limestone and dolomite predominate in the section. 

Fossils from these strata indicate that they are as young as Toarcian 

(late Early Jurassic) in age.

Numerous stratigraphically isolated exposures of Upper Triassic 

and Jurassic strata to the north and west of the Humboldt Range 

present even greater problems of correlation with the Auld Lang Syne 

Group. Although the lithology and sparse fossil content of these 

strata indicate their relation to the group, it is presently impossible 

to refer many of them to specific parts of the group.

In south-central Humboldt County, outside the area of the Santa 

Rosa Range and Bloody Run Hills, Willden (1964, p. 43-47) locally 

recognized the Winnemucca and Raspberry Formations. Although 

Willden's report was published after Compton's (1960) report, it had 

apparently been written somewhat earlier, for his "unnamed quartzite and mudstone formation" between the Winnemucca and Raspberry Formations in the Krum Hills corresponds to Compton's O'Neill 

Formation (fig. 3).

Thick sections of strata that are lithologically similar to, and correlative with, the Auld Lang Syne Group crop out over large areas of 

western Humboldt, western Pershing, and Washoe Counties. These 

strata are in part the Triassic and Jurassic (?) "phyllite, slate and 

quartzite unit" of Willden (1964, p. 49-50) in Humboldt County and 

the "Nightingale sequence" of Bonham (1969, p. 6) in Washoe County.

STRATA SOUTH AND EAST OF THE TYPE AREA

The Grass Valley, Dun Glen, and Winnemucca Formations, overlying the massive carbonate strata of the Natchez Pass Formation 

(Muller and others, 1951), have been mapped to the south and east 

of the East Range. In the northern Stillwater Range, the upper half 

of the Grass Valley Formation is predominantly cross-stratified micaceous and feldspathic sandstone. In the south end of the Tobin Range, 

the correlative beds are entirely sandstone with only a few thin intercalations of argillite and limestone. In the northern Augusta Mountains, lithologically similar sandstone, with persistent beds of 

fossiliferous limestone in the upper part, were defined as the Osobb
E12 CONTRIBUTIONS TO STRATIGRAPHY

Formation by Muller, Ferguson, and Roberts (1951). Like the Grass 

Valley, the Osobb overlies a massive carbonate unit, the Cane Spring 

Formation. It is now apparent that these various exposures demonstrate the interfingering of typical Grass Valley and Osobb strata 

above formations that can be assigned to the Star Peak Group. 

Because the strata that have been mapped as Grass Valley Formation 

in the southern Tobin Range (Muller and others, 1951) are almost 

entirely sandstone, they are reassigned to the Osobb Formation (fig. 

3). For these reasons, therefore, the Osobb is included within the Auld 

Lang Syne Group.

Still farther to the south in the Stillwater Range, the Clan Alpine 

Mountains, and southernmost Augusta Mountains, Page (1965) and 

Speed and Jones (1969) have described a very thick sequence of 

Upper Triassic and Jurassic terrigenous clastic and carbonate rocks 

that are lithologically similar to the Auld Lang Syne Group. Speed 

and Jones (1969) have informally divided the Mesozoic rocks that 

predate their Boyer Ranch Formation (Jurassic) into three mapping 

units (units I, II, and III), and these units are equivalent in part to 

the Koipato, Star Peak, and Auld Lang Syne Groups as they are 

defined to the north. Unit II consists of the entire exposed sequence 

of Triassic rocks in the northernmost Stillwater Range and the 

Augusta Mountains; it includes the volcanic and tuffaceous sedimentary rocks of the Koipato Group, the carbonate rocks of the Star Peak 

Group and its lateral equivalents, and the predominantly terrigenous 

clastic rocks of the Osobb Formation, regarded here as the lower part 

of the Auld Lang Syne Group. The strata of unit I are slaty or phyllitic shale, siltstone, and sandstone, with intercalations of massive 

limestone and dolomite in the highest part of the sequence in the Clan 

Alpine Mountains.

Fossils collected thus far from unit I indicate that it is everywhere 

younger than the Star Peak Group and that its lower part is correlative with the lower part of the Auld Lang Syne Group (that is, the 

lower part of unit I is correlative with the uppermost part of unit II). 

In the Stillwater and West Humboldt Ranges, unit I grades upward 

into Lower Jurassic calcareous siltstone, shale, and silty limestone 

designated as unit III. Although generally similar in composition to 

the Auld Lang Syne Group, the terrigenous clastic rocks of units I 

and III were deposited under a different and generally more marine 

regime than the Auld Lang Syne Group and are not amenable to subdivision into formational units coordinate with those of the Auld Lang 

Syne Group. These seemingly abrupt lithologic differences between 

units I and III and the Auld Lang Syne Group may simply be the 

result of lateral variations in depositional environment and provenance, but they may in part be the result of significant thrust trans-
AULD LANG SYNE GROUP, TRIASSIC AND JURASSIC (?) E13

lation of units I and III during later Jurassic orogeny (Speed and 

Jones, 1969).

PALEOGEOGRAPHIC INTERPRETATION

The Auld Lang Syne Group and its lithologic correlatives in northwestern Nevada are composed of an impressive volume of sedimentary 

material. If the combined thickness of the East Range and Santa 

Rosa Range sections is not abnormal (and the thick but stratigraphically isolated exposures elsewhere suggest that it is not), at least 

100,000 cubic miles of these sediments were deposited in Humboldt, 

Pershing, and Washoe Counties alone. This volume of material is 

enough to cover the entire United States and its territories to a depth 

of more than 100 feet.

In the absence of a more formal terminology, geologists working in 

northwestern Nevada have long referred to the post-Star Peak Group 

Mesozoic strata as "the mud pile," and no succinct term could better 

express the homogeneous lithologic character of these strata. Only 

where the Star Peak Group supplies a reference datum or where the 

Dun Glen Formation serves as a marker unit have these rocks been 

amenable to lithologic correlation. The homogeneity that sets "the 

mud pile" apart as a separate stratigraphic entity has also been the 

major impediment to its more detailed understanding.

Wherever they have been spared from the extreme effects of later 

metamorphism, and regardless of their stratigraphic position within 

the group, the mineralogic and sedimentary features of the Auld Lang 

Syne Group and related strata indicate that their lithologic homogeneity is largely the reflection of a consistent provenance and depositional environment during Late Triassic and Early Jurassic time 

(Compton, 1960; Silberling and Wallace, 1969). This enormous volume of material was transported from the east and was deposited 

under very shallow marine conditions, apparently on and around a 

large westerly prograding delta. Beach and bar sands occur in minor 

amounts throughout the group, particularly at its base in the more 

southeastern exposures (the Osobb Formation), and periods of locally 

reduced terrigenous clastic influx are manifested by shallow-water 

carbonate units such as the Dun Glen Formation. By far the greatest 

fraction of the total rock volume, however, was formed from argillaceous and silty sediment deposited under deltaic conditions.

Although transport of these clastic materials was clearly from the 

east (Silberling and Wallace, 1969; El-Hawat, 1970), the source of 

these sediments is something of an enigma. Compton's (1960) study 

of the rocks of the Santa Rosa Range shows them to be consistent in 

overall mineralogy and unlike what would be expected if they were 

derived from the Paleozoic rocks of western or central Nevada (Sil-
E14 CONTRIBUTIONS TO STRATIGRAPHY

berling and Wallace, 1969). The source of the Auld Lang Syne clastic 

sediments must have been farther east, perhaps from the Colorado 

Plateau or Rocky Mountain regions as suggested by Silberling and 

Wallace (1969). This interpretation supports the conclusion of Stanley, Jordan, and Dott (1971) that no significant highlands the 

Mesocordilleran geanticline separated western Nevada from the 

continental interior during middle Mesozoic time.

REFERENCES CITED

Bonham, H. F., 1969, Geology and mineral deposits of Washoe and Storey 

Counties, Nevada: Nevada Bur. Mines Bull. 70, 140 p.

Burke, D. B., 1970, Reinterpretation of the "Tobin Thrust," west-central 

Nevada: Geol. Soc. America Abs. with Programs, v. 2, no. 2, p. 78.

Compton, R. R., 1960, Contact metamorphism in the Santa Rosa Range, Nevada: 

Geol. Soc. America Bull., v. 71, no. 9, p. 1383-1416.

El-Hawat, A. S., 1970, Depositional environments of Lower Norian (Upper 

Triassic) sandstones in the Tobin Range and Augusta Range, northwestern 

Nevada: Stanford, Calif., Stanford Univ., M.S. report, 42 p.

Ferguson, H. G., Muller, S. W., and Roberts, R. J., 1951a, Geology of the Mount 

Moses quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-12.

 1951b, Geology of the Winnemucca quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-11.

Ferguson, H. G., Roberts, R. J., and Muller, S. W., 1952, Geology of the Golconda quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-15.

Muller, S. W., Ferguson, H. G., and Roberts, R. J., 1951, Geology of the Mount 

Tobin quadrangle, Nevada: U.S. Geol. Survey Geol. Quad. Map GQ-7.

Page, B. M., 1965, Preliminary geologic map of a part of the Stillwater Range, 

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* U.S. GOVERNMENT PRINTING OFFICE: 1973 543 578/28