Stratigraphic Nomenclature 

for the Upper Devonian and 

Lower Mississippian(P) 

Kanayut Conglomerate, 

Brooks Range, Alaska

U.S. GEOLOGICAL SURVEY BULLETIN 1529 A

Stratigraphic Nomenclature 

for the Upper Devonian and 

Lower Mississippian(P) 

Kanayut Conglomerate, 

Brooks Range, Alaska

By TOR H. NILSEN and THOMAS E. MOORE 

CONTRIBUTIONS TO STRATIGRAPHY

U.S. GEOLOGICAL SURVEY BULLETIN 1529 A

A description and redefinition of the 

Kanayut Conglomerate in terms of 

three fluvial members

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1984
UNITED STATES DEPARTMENT OF THE INTERIOR 

WILLIAM P. CLARK, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data 

Nilsen, Tor Helge

Stratigraphic nomenclature for the upper Devonian and lower Mississippian(P) 

Kanayut Conglomerate, Brooks Range, Alaska.

(Contributions to stratigraphy) (Geological Survey Bulletin 1529-A)

Bibliography: p.

Supt. of Docs, no.: I 19.3:1529-A.

1. Conglomerate Alaska Brooks Range. 2. Geology, Stratigraphic 

Devonian. 3. Geology, Stratigraphic Mississippian. I. Moore, Thomas E.

II. Title. III. Series. IV. Series: Geological Survey Bulletin 1529-A. 

QE75.B9 no. 1529-A 557.3s [551.7'4'097986] 84-600062 [QE471.15.C6]

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Page

Abstract 1 

Introduction - - ~~ - - . - . - 9

Previous work - - - - - - - - 8

Noatak Sandstone 10

Kanayut Conglomerate -- - - - - - -- - - 13

Regional framework - 13

Ear Peak Member - - - - - - - - 16

Definition - - - - - - - - - 16

Areal extent - - - - - -- - 18

Type section - - -- - ......... .... ^g

Stratigraphic relations - - - - - 32 

Thickness - ----- - -- - 33

Depositional environment -- - - - - - 34 

Age and correlation 34 

Shainin Lake Member - - - - - - ... . 35 

Definition 35 

Areal extent - - - - - - - - - 36 

Type section - - - - - - - -- 36 

Stratigraphic relations 49 

Thickness 49

Depositional environment - - - - - - - 49 

Age and correlation - - - - -- - 50 

Stuver Member - - - - - - - 59 

Definition - - - - - - -- 50 

Areal extent - - - - - - - 51

Type section . . . - 52

Stratigraphic relations 59

Thickness - - - - ----- - 60

Depositional environment - - - - - - 60

Age and correlation - - - - - - -- 60

Kayak Shale - . . . . - - - - 5 \

Summary and conclusions - - - - - - - - -- - 62

References cited - - - - 63

ILLUSTRATIONS

Page

FIGURE 1. Map of northern Alaska, showing outcrops of the Kanayut Conglomerate and major geographic features ----- - - - - 3

2. Index map showing locations of outcrops of the Kanayut Conglomerate in the central and eastern Brooks Range 4

3. Simplified columnar sections illustrating Stratigraphic nomenclature of the allochthonous and autochthonous sequences of the 

Endicott Group - - - - - 5

m
IV CONTENTS

FIGURE 4. Chart illustrating historical development of stratigraphic and age 

assignments of the Kanayut Conglomerate and associated units of 

the allochthonous sequence of the Endicott Group 6

5. Simplified geologic map showing locations of measured type sections of members of the Kanayut Conglomerate - 12

6. Photograph showing typical outcrops of the Stuver Member of the 

Kanayut Conglomerate east of the Atigun River, central Brooks 

Range . ...... ..... \ 4

7. Photograph showing ridgecrest exposures of the Kanayut Conglomerate near the Atigun River 15

8. Schematic cross section of the Endicott Group, showing pinchout to 

south and west of the Shainin Lake Member of the Kanayut Conglomerate 16

9. Chart illustrating differences in stratigraphic subdivision of the

Kanayut Conglomerate in the central Brooks Range 17

10. Photograph of measured type section of the Ear Peak Member of

the Kanayut Conglomerate at Ear Peak - 20

11. Columnar section illustrating type section of the Ear Peak Member

of the Kanayut Conglomerate 21

12. Oblique aerial photograph showing location of measured type section of the Shainin Lake Member of the Kanayut Conglomerate 

south of Shainin Lake - - - 37

13. Columnar section illustrating type section of the Shainin Lake

Member of the Kanayut Conglomerate 38

14. Photograph showing measured type section of the Stuver Member

of the Kanayut Conglomerate southeast of Shainin Lake 53

15. Columar section illustrating type section of the Stuver Member of

the Kanayut Conglomerate 54
CONTRIBUTIONS TO STRATIGRAPHY

STRATIGRAPHIC NOMENCLATURE FOR 

THE UPPER DEVONIAN AND

LOWER MISSISSIPPIAN(P)

KANAYUT CONGLOMERATE,

BROOKS RANGE, ALASKA

By TOR H. NILSEN and THOMAS E. MOORE

ABSTRACT

The Kanayut Conglomerate, of Late Devonian and Early Mississippian(?) age, 

is one of the thickest and most laterally extensive stratigraphic units of the Brooks 

Range, northern Alaska. It is a coarse-grained clastic unit, as thick as 3,000 m, that 

extends for about 950 km along the length of the range from near the Alaska-Yukon 

Territory border to near the coast of the Chukchi Sea. The Kanayut forms the middle part of a large, dominantly fluvial delta that prograded south westward over 

marine strata of the Noatak Sandstone and the Hunt Fork Shale, retreated, and was 

then overlapped by marine strata of the Kayak Shale. The Kanayut Conglomerate 

now crops out in a series of thrust plates that are thought to have been transported 

northward during a Mesozoic orogeny.

The Kanayut Conglomerate was previously divided into one formal and three informal members consisting of both marine and nonmarine deposits. We herein redefine (stratigraphically restrict) the Kanayut Conglomerate to consist of three formal 

members, each of which is almost wholly fluvial in origin. We consider the informal 

marine basal sandstone member, heretofore assigned to the Kanayut Conglomerate, 

to be equivalent to the marine Noatak Sandstone of the western Brooks Range, and 

we here apply that name to it. Thus restricted, the Kanayut Conglomerate consists, 

in ascending order, of: the Ear Peak Member (new name), a sequence of fining-upward fluvial cycles of conglomerate, sandstone, and shale, as thick as 1,160 m, 

thought to have been deposited chiefly by meandering streams; the Shainin Lake 

Member (new name), a sequence of fining-upward couplets of conglomerate and 

sandstone, as thick as 530 m, thought to have been deposited by braided streams; 

and the previously named and herein redefined (stratigraphically extended) 

Stuver Member, a sequence of fining-upward fluvial cycles of conglomerate, 

sandstone, and shale, as thick as 1,300 m, thought to have been deposited chiefly 

by meandering streams. These three fluvial members have been traced across most 

of the eastern and central Brooks Range. Where the more resistant Shainin Lake 

Member pinches out in the western Brooks Range, the Kanayut Conglomerate is undivided. A ]
A2 CONTRIBUTIONS TO STRATIGRAPHY

INTRODUCTION

The Kanayut Conglomerate is one of the major stratigraphic 

units of northern Alaska. The Kanayut crops out in the Brooks 

Range over an east-west distance of about 900 km and a north-south 

distance of about 65 km (fig. 1). It was originally defined by 

Bowsher and Dutro (1957) for exposures in the Shainin Lake area 

(fig. 2), where the upper part of the unit was formally designated 

the "Stuver Member." A variety of informal names and stratigraphic terms have been applied to the Kanayut Conglomerate since 

1957, on the basis of mapping by various geologists in different 

areas. Our studies of the stratigraphy and sedimentology of the 

Kanayut Conglomerate in the Brooks Range since 1978 have been 

concentrated in the central and eastern areas. In this report we propose a formal stratigraphic nomenclature for the different parts of 

the Kanayut by defining two new members. Our nomenclatural 

scheme is based primarily on studies of lateral and vertical stratigraphic relations by the measurement of sections in the field.

The middle Paleozoic rocks of the Brooks Range form a thick 

clastic sequence that conformably overlies and is conformably overlain by platform carbonate rocks. Tailleur and others (1967) designated the lower carbonate sequence the "Baird Group," presently 

regarded as Silurian to Late Devonian in age, and the clastic sequence the "Endicott Group," currently regarded as Late Devonian 

and Early and Late Mississippian in age. Bowsher and Dutro (1957) 

had previously designated the upper carbonate sequence the "Lisburne Group," which is presently considered to be Mississippian and 

Pennsylvanian in age.

The Endicott Group, as defined by Tailleur and others (1967), 

consists of a succession of shale, sandstone, and conglomerate in the 

central Brooks Range that includes, in ascending order: the Hunt 

Fork Shale, the Kanayut Conglomerate, and the Kayak Shale. In 

the western Brooks Range, Dutro (1952, 1953a, b) recognized the 

Noatak Sandstone as the coarse clastic unit of the Endicott Group 

and correlated it with the Kanayut Conglomerate. In the northeastern Brooks Range, in the subsurface beneath the North Slope (fig. 

2), and along the south margin of the Brooks Range, the Endicott 

Group consists of the Kekiktuk Conglomerate and the Kayak Shale 

(Brosge and others, 1962) and the Itkilyariak Formation (Mull and 

Mangus, 1972). The Kekiktuk Conglomerate and the Kayak Shale 

along the south edge of the Brooks Range are in part metasedimentary (Mayfield and Tailleur, 1978; Nelson and Grybeck, 1980). In the 

southeastern Brooks Range, Dutro and others (1979) mapped and 

described the Upper Devonian (Frasnian) marine Beaucoup Formation, a mixed clastic and carbonate unit that they concluded conformably underlies the Hunt Fork Shale and disconformably overlies
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A3

O 

-t-i

I

platform carbonate rocks of the Baird Group. The Beaucoup Formation, however, is not included in the Endicott Group.

The clastic units of the Endicott Group form two distinct sequences whose original spatial juxtaposition is uncertain (Tailleur and 

others, 1967, p. 1359; Mull and Tailleur, 1977; Nilsen, 1981). The first 

sequence is wholly allochthonous and consists of a conformable sequence of the Hunt Fork Shale, the Kanayut Conglomerate, and the 

Kayak Shale (fig. 3). The second sequence is autochthonous or 

parautochthonous and consists of the Kekiktuk Conglomerate, the
Ill

3 § W £ g e159° 156° 153

M O Q

&3 O

H* H^ 03

CO *>^

3 § KH (D 2 <r>-

iff 

II

CO 0> 03 ^ja CT- § 3 5' 

B.3 s

O X S O &. a

EXPLANATION \

Location of measured sections

A Stuver Member 

i Shainin Lake Member » Ear Peak Member 

Boundary of physiographic provinces _ Outcrop of the Kanayut Conglomerate

5 WISEMAN 

RANGE

SURVEY PASS 

BROOKS

67

G FIGURE 2. Index map of central and eastern Brooks Range, showing locations of outcrops of the Kanayut Conglomerate.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A5

Middle Devonian granitic intrusive rocks. This report addresses the 

stratigraphic subdivision of the allochthonous Kanayut Conglomerate 

and is not concerned with the stratigraphic nomenclature of the autochthonous sequence.

The Kanayut Conglomerate has been considered Late Devonian by 

most earlier workers (fig. 4). The unit contains abundant plant fossils, 

chiefly in its lower and upper parts, that are Late Devonian (Bowsher 

and Dutro, 1957; Porter, 1966). At one locality in the Wiseman quadrangle, the Kanayut contains Late Devonian brachiopods in a marine 

tongue near its top (J. T. Dutro, Jr., oral commun., 1981). At some 

localities, however, the Stuver Member of the Kanayut also contains 

some plant fossils of probable Early Mississippian age (S. H. Mamay, 

written commun., 1980). We therefore consider the Stuver, as well as

ALLOCHTHONOUS SEQUENCE AUTOCHTHONOUS SEQUENCE

u1 -

2-

3-

4-

5- 

6- 

7- 

R

MISSISSIPPI ISSISSIPq 

I |PIAN(?) PIAN 

i

DEVONIAN 1 Jnnnr

Lisburne Group

A

/

_\

-T-4

(Shallow marine)

i i ii {/ Kayak Shale ^ *~ 

1~^=-II^ (shallow to deep marine) s

fljjtff t'tf Stuver Member 1

O Q QO Ool Shainin Lake 

OooJ?Oo) Member 

°O ^0° (braided stream)

^^^°^o} Far Paalt

h^j^y-^) Member 

^^^^^^^ (meandering stream)

Group Endicott 

. ' O' B o o' ol J

 ' , , -., -4

_^_^ / (Shallow marino)

P

wacke member 

(shallow to deep 

marine)

p.--=|

=r-~^-m Shale member

^%

>r-^r--5y^ (Shallow to deep 

_goqoqr>5) marine and 

 ^Y^P^T nonmarine)

/

Cor

|

\

| \

\

~_E( Kayak

//Hiatus

Kanayut 

iglomerate

> Noatak 

Sandstone

v Hunt Fork 

? Shale

Beaucoup 

Formation

Shale

^ Kekiktuk Conglomerate

/ \ (braided and 

/ S meandering stream)

X

cAri

Lir 

Sha

Shale i 

no

Sa

Con 

Unc

LANA 1 IUN

1 I T

1 1 nesto

 -

ne

le,marine

md siltstone, 

nmarine

ndstone

^o°o

glome

~~S^-sonfor

rate 

nity

FIGURE 3. Simplified columnar sections showing stratigraphic nomenclature of allochthonous and autochthonous sequences of the Endicott Group.
A6 CONTRIBUTIONS TO STRATIGRAPHY

the Kanayut, to be Late Devonian and Early Mississippian(?) in age. 

The oldest marine fossils from the overlying Kayak Shale are Kinderhookian but not earliest Kinderhookian, an age permitting the uppermost part of the Kanayut to be Early Mississippian. The uppermost 

part of the Kanayut Conglomerate in the western Brooks Range is

£

CO

z

Q.

CO

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*

-1

1

1

z

i

UJ

o

.£

CO

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o

_I

 >* 

5

1

^

CO

1j?

ta

8

1

*

u

(O

F

(O

to

zUSchrader 

(1902,1904)

Central

Brooks Range

Lisburne

Formation

Stuver

Series

o

Smith and 

Mertie(1930)

Northwestern

Alaska

Noatak

Sandstone

Dutro(1 952,1 953a,b)

Noatak River.western

Brooks Range

Utukok

Formation

Noatak

Formation

Hunt

Fork(?)

Formation

Shainin Lake, central

Brooks Range

o

i

to

2

0

F

0

3

to

to

2t

Red limestone

member

Upper black 

shale member

Argillaceous 

limestone member

Lower black 

v shale member /

member

Stuver

Member

Middle

conglomerate

member

Lower

conglomerate

member

Hunt

Fork

Formation

Bowsher and 

Dutro(1957)

Shainin Lake, central

Brooks Range

CO

1

S 

F

0

o

3

to

to

 *-

Red limestone

member

Upper black 

shale member

Argillaceous 

limestone member

Lower black 

v shale member /

member

Stuver

Member

Middle

conglomerate

member

Lower

member

Unnamed

sandstone

and shale

FIGURE 4. Historical development of stratigraphy and age assignments of the 

Kanayut Conglomerate and associated units of allochthonous sequence of the 

Endicott Group.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A7

thought to be Early Mississippian in age (L L. Tailleur, written commun., 1982). Marine megafossils from the underlying Hunt Fork Shale 

and Noatak Sandstone are Frasnian (early Late Devonian) and Famennian (late Late Devonian). These ages restrict the nonmarine part of 

the Kanayut to the late Famennian and early Kinderhookian(?).

Porter (1966)

Anaktuvuk Pass, 

central Brooks Range

Kayak 

Shale

Stuver 

Member

§ Conglomerate

_o

 member

o

S Lower 

member

Hunt 

Fork

Shale

Tailleur and 

others (1967)

Western Brooks Range 

West * East

o

C3

O 

LLJ

*

( 

( 

( 

(

Noata

Sandsto

<

( 

_^ I 

Hunt ^ 

Fork

Shale 

C

<

) 

Kayak

) 

Shale

>

)

Kanayut

nglomerate

/

> 

~\ Hunt

^ Fork 

) 

) Shale

) 

> 

\

Brosge and others (1979a,b); 

Nlsen and others (1980,1981, 

1982); Nilsen(1981)

Central and eastern 

Brooks Range

Kayak 

Shale

E 

"o» 

o

> .

CO

X

Stuver 

Member

Middle 

conglomerate 

member

Lower

shale 

member

(Basal) 

sandstone member

Wacke 

member

Shale 

member

Nelson and 

Grybeck (1980)

Upper Killik River, 

central Brooks Range

Kayak 

Shale

E

~OJ

o 

o

>, 

^

Upper 

quartzite 

unit

Lower 

sandy 

unit

Hunt

Fork 

Shale

This report

Central and eastern 

Brooks Range

CO

^

E

o 

0

>, 

^

Red limestone 

member

Upper black shale

Argillaceous 

limestone member

Lower black shale

Basal sanstone 

member

Stuver 

Member

Shaimn 

Lake 

Member

Ear Peak 

Member

Noatak 

Sandstone

CO

_^

o 

u.

X

Wacke 

member

Shale 

member

FIGURE 4. Continued
A8 CONTRIBUTIONS TO STRATIGRAPHY

PREVIOUS WORK

Strata of the "Stuver series," later incorporated within the 

Kanayut Conglomerate, were first described by Schrader (1902, p. 240; 

1904, p. 60-62). He noted chiefly a very hard silica-cemented conglomerate that contained interbeds of quartzite and included some shale at 

the top. The conglomerate clasts, as large as small boulders, were described as consisting chiefly of chert and white quartz. Schrader (1904, 

p. 62) reported an exposed thickness of at least 600 m.

Smith and Mertie (1930, p. 155) included these strata within the 

Noatak Sandstone. Dutro (1952, 1953a, b) separated his Kanayut "formation" from the Noatak Sandstone as a mappable unit, although he 

recognized that his redefined Noatak Sandstone in the western Brooks 

Range was correlative with the redefined Kanayut "formation" in the 

central Brooks Range. J. T. Dutro, Jr., and A. L. Bowsher (in Dutro, 

1952, app. G) measured a section of the Kanayut that was 1,150 m thick 

in the Kanayut Lake (later renamed "Shainin Lake") area, and Patton 

and others (1951, p. 5) measured a second section 1,450 m thick along 

the Okokmilaga River.

Dutro (1952), on the basis of fieldwork by A. L. Bowsher and himself, described three members of the Kanayut "formation" in the 

Shainin Lake area: (1) the lower conglomerate member, chiefly conglomerate containing thin beds of sandstone, about 485 m thick; (2) the 

middle conglomerate member, almost all conglomerate, about 310 m 

thick; and (3) the Stuver Member, consisting of interbedded quartzite, 

conglomerate, and shale, as thick as 310 m. The Stuver Member corresponded to the "Stuver series" as described by Schrader (1902, 

1904).

Bowsher and Dutro (1957) defined three nonmarine members of 

the Kanayut Conglomerate in the Shainin Lake area, in ascending 

order: the lower member, the middle conglomerate member, and the 

Stuver Member. The lower member was measured, but not described, 

in a section north of Ear Peak. A type section for the informally named 

middle conglomerate member was measured along the east side of 

Alapah Creek, about 12 km southeast of Shainin Lake. The type locality for the Stuver Member was designated, and a section measured, 

along a ridgecrest southeast of Shainin Lake.

Porter (1966), working in the Anaktuvuk Pass area, recognized a 

fourth and lowest member of chiefly marine sandstone that is absent in 

the Shainin Lake area. Porter (1966) tentatively correlated this unit 

with the lower member of Bowsher and Dutro (1957). In preliminary 

regional maps of the Philip Smith Mountains area (Brosge and others, 

1979a) and the area between the Killik River and the Trans-Alaska 

Pipeline (Brosge and others, 1979b), the Kanayut Conglomerate was
RANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A9

divided into these four previously described members. Porter's (1966) 

lowest, partly marine unit was informally designated the "basal 

sandstone member," and the three nonmarine units were designated 

the "lower shale member," the "middle conglomerate member," and 

the "Stuver Member."

Stratigraphic and sedimentologic studies of the Kanayut Conglomerate and related stratigraphic units of the Endicott Group in the central and eastern Brooks Range from 1978 to 1980 were summarized by 

Nilsen and others (1980, "1981) in a series of reports covering the results from each field season. These reports include numerous measured 

sections of the various units of the Kanayut Conglomerate in the eastern and central Brooks Range. The Kanayut in these reports is divided 

into the four members of Brosge and others (1979a).

Nelson and Grybeck (1980), mapping in the upper Killik River 

area (Survey Pass quadrangle), divided the Kanayut Conglomerate 

into a lower or undifferentiated sandy unit and an upper or quartzitic 

unit. We infer, on the basis of our stratigraphic work, that the lower, 

sandy unit is equivalent to Porter's (1966) lowest member of the 

Kanayut (basal marine sandstone member of Brosge and others, 1979a) 

and that the upper, quartzitic unit represents the undivided upper 

three nonmarine members.

W. P. Brosge and others (unpub. data, 1982) have mapped at a 

scale of 1:500,000 the distribution of various mappable units of the 

Kanayut Conglomerate across the central and eastern Brooks Range. 

They have restricted the Kanayut Conglomerate to the upper three 

nonmarine units and have designated the marine basal sandstone member the "Noatak Sandstone," with which it is correlative and into which 

it can be traced westward.

In the western Brooks Range, Mayfield and Tailleur (1978) and 

Mayfield and others (1978) mapped the Kanayut Conglomerate as part 

of the Endicott Group. Our preliminary (1981) work in the DeLong 

Mountains, western Brooks Range, indicates the presence of the 

Kanayut Conglomerate as far west as the Mulgrave Hills, adjacent to 

the coast of the Chukchi Sea, where it conformably overlies the Noatak 

Sandstone and is conformably overlain by the Kayak Shale (Nilsen and 

Moore, 1982). In this area, however, the members of the Kanayut are 

not readily distinguishable.

In this report, we adopt the stratigraphic restriction of the 

Kanayut Conglomerate to its three nonmarine members; additionally, 

we formally propose names and type sections for the heretofore informal, lower two members. The lower shale member (lower member of 

Bowsher and Dutro, 1957) is here formally named the "Ear Peak Member," and the middle conglomerate member the "Shainin Lake Member." Together with the previously designated Stuver Member, the
A10 CONTRIBUTIONS TO STRATIGRAPHY

type sections of all three members are near Shainin Lake in the northcentral Brooks Range (fig. 5). The Kanayut River, for which the 

Kanayut Conglomerate was named, flows northward from Shainin 

Lake, which forms its source. The previous lowermost member of the 

Kanayut, heretofore referred to as the (basal marine) "sandstone member" by Brosge and others (1979a, b), Nilsen and others (1980, 1981), 

and Nilsen (1981), is here reassigned to the Noatak Sandstone.

NOATAK SANDSTONE

The type area of the Noatak Sandstone is in the south-central DeLong Mountains of the western Brooks Range, along the Nimiuktuk 

River, north of its confluence with the Noatak River (Dutro, 1952, 

1953a, b). The Noatak "formation" was first described by Smith (1913, 

p. 70) for exposures of mainly sandstone along the Noatak River. 

Smith and Mertie (1930, p. 165) expanded this definition to include all 

the middle Paleozoic clastic rocks above the Skajit Limestone and 

below the Lisburne Group in northwestern Alaska.

The Noatak Sandstone, as defined by Dutro (1952, 1953a, b), is 215 

to 305 m thick in the type area, although a thickness of as much as 

1,000 m was reported in other parts of the western Brooks Range 

(Tailleur and others, 1967, p. 1355). In its type area, the Noatak consists chiefly of sandstone, and minor amounts of shale and conglomerate. Dutro (1952, p. 7) reported that the rock has mainly a siliceous cement except at the top of the unit, where it is partly calcareous. On 

weathered surfaces, alteration of iron minerals to limonite results in a 

typical reddish-brown color. Large- and small-scale cross-strata are 

common in the sandstone. Dutro (1952) reported a conglomerate-clast 

composition of approximately 75 percent vein quartz, 15 percent 

medium- to dark-gray chert, and 10 percent slate and phyllite.

In its type area, the Noatak Sandstone rests conformably on shale 

and fine-grained sandstone of the Hunt Fork Shale and is overlain conformably by the Utukok Formation. Marine fossils from the underlying 

Hunt Fork Shale and the overlying Utukok Formation, as well as from 

the Noatak itself, suggest a Late Devonian and Early Mississippian 

age for the Noatak Sandstone. Dutro (1952, 1953b) correlated the 

Noatak Sandstone with the Kanayut Conglomerate to the east. More 

recent mapping by the U.S. Geological Survey in the type area of the 

Noatak Sandstone indicates the presence of a stratigraphic sequence 

that consists of the Hunt Fork Shale, the undivided Noatak Sandstone 

and Kanayut Conglomerate, the Kayak Shale, and the Utukok Forma-
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA All

tion (C. F. Mayfield, oral commun., 1982). The Utukok Formation, 

about 215 m thick, consists mainly of sandstone and limestone, with 

some gray to black shale near its base (Dutro, 1952, 1953b). The 

Utukok crops out in the western Brooks Range and is a part of the Lisburne Group (Tailleur and others, 1967). Dutro (1952, fig. 1) considered 

the Utukok Formation to be correlative with the Kayak Shale of the 

central and eastern Brooks Range.

The Noatak Sandstone of the central and eastern Brooks Range, 

previously referred to as the basal sandstone member of the Kanayut 

Conglomerate, is a laterally discontinuous unit that gradationally overlies the Hunt Fork Shale and is gradationally overlain by and laterally 

interfingers with the Ear Peak Member of the Kanayut Conglomerate. 

Where present, the Noatak varies in thickness from 90 to 560 m 

(Nilsen and others, 1980). It locally contains middle Famennian (late 

Late Devonian) shallow-marine megafossils in this area (Nilsen and 

others, 1980). These megafossils, which include brachiopods, gastropods, pelecypods, and echinoderm debris, indicate deposition in 

shelf, intertidal, lagoonal, and marginal-marine settings. Various types 

of marine trace fossils are locally present, including Skolithos.

In the central and eastern Brooks Range, the Noatak Sandstone 

consists chiefly of medium-bedded cross-stratified fine- to mediumgrained quartzose sandstone that is locally conglomeratic, containing 

pebbles as long as several centimeters. The rock typically has a calcareous cement and weathers light gray to light brown. It characteristically forms bundles or packages of sandstone as thick as 15 m that are 

intercalated within red, brownish-gray, and black shale. These 

sandstone bundles most typically thicken and coarsen upward; we interpret them to represent various types of shelf and shoreline accumulations of sand, probably related to shoreline progradation, although 

we have not studied them in detail. Varying paleocurrent orientations 

indicate the divergence of shelf and shoreline current patterns.

We have not measured any complete sections of the Noatak 

Sandstone in the central and eastern Brooks Range only the upper 

part of it adjacent to its contact with the Ear Peak Member of the 

Kanayut Conglomerate (Nilsen and others, 1980, 1981, 1982). In the 

westernmost Brooks Range, in the Mulgrave Hills and the western DeLong Mountains, it interfingers with and is overlain gradationally by 

the lower part of the Kanayut Conglomerate (Nilsen and Moore, 1982). 

In the type section of the Noatak Sandstone along the Nimiuktuk 

River, I. L. Tailleur (written commun., 1982) concludes that the 

Kanayut Conglomerate pinches out and is both underlain and overlain 

by the Noatak Sandstone. However, we have not seen the type section 

of the Noatak and thus cannot verify this suggested relation.
A12 CONTRIBUTIONS TO STRATIGRAPHY

151°00' R. 5 E. R. 6 E.

68°20

0123 MILES 

CONTOUR INTERVAL 100 FEET

FIGURE 5. Simplified geologic map showing locations of measured type sections of 

members of the Kanayut Conglomerate. Section 1 is type section of the Ear Peak 

Member, section 2 of the Shainin Lake Member, and section 3 of the Stuver Member. Geology modified from Bowsher and Dutro (1957), W. P. Brosge (unpub. data, 

1976-80), and Hamilton (1979). Base from l:63,360-scale Chandler Lake A-2 and B-2 

quadrangle maps.
Qs

Ml

KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A13

EXPLANATION

Surficial deposits (Quaternary) Dkep Ear Peak Member (Upper

___ Devonian)

Lisburne Group (Mississippian) ~ Hunt Fork Shale (Upper Devonian)

Kayak Shak (Mississippian) Contact-Dotted where concealed

Kanayut Conglomerate (Lower

,..... . Tt Fault Mississippian? and Upper

Devonian) Consists of: -A A. Thrust fault Dotted where conStuver Member (Lower Missis - cealed. Sawteeth on upper plate

sippian?and Upper Devonian) === Mtasmed sectjon 

Shainin Lake Member (Upper

Devonian)

FIGURE 5. Continued

KANAYUT CONGLOMERATE

REGIONAL FRAMEWORK

Outcrops of the Kanayut Conglomerate generally form ridges that 

are marked by prominent ribs or resistant ledges of conglomerate and 

sandstone, separated by less resistant covered recesses underlain by 

siltstone and shale (fig. 6). These ledges are thought to record individual fining-upward depositional cycles within the Kanayut, in which 

the coarser grained lower strata represent channel fills and the finer 

grained upper strata represent flood plains. In several localities, thick 

sections of the Kanayut that contain all three members form extensive 

upland ridges marked by alternating resistant and less resistant bands 

(fig. 7).

The lithology of the Kanayut Conglomerate changes markedly 

from east to west and from north to south in the Brooks Range. The 

most conspicuous changes toward the south and west are gradual thinning of the entire unit and each of its members, gradual fining of the 

conglomerate-clast sizes in the entire unit and each of its members, increasing number and thickness of beds of intercalated marine strata, 

and pinchout of the Shainin Lake Member as a recognizable, mappable 

stratigraphic unit (fig. 8).

In the central and eastern Brooks Range, the three members of 

the Kanayut Conglomerate can generally be readily distinguished and 

mapped (Brosge and others, 1979a, b; W. P. Brosge and others, unpub. 

data, 1982). Because the Shainin Lake Member pinches out southward, 

however, the three members cannot everywhere be distinguished in 

the southernmost outcrops of the unit in the central and eastern
A14 CONTRIBUTIONS TO STRATIGRAPHY

FIGURE 6. Typical outcrops of the Stuver Member of the Kanayut Conglomerate, showing alternating resistant coarse-grained fluvial-channel deposits and less resistant finegrained flood-plain deposits east of the Atigun River, central Brooks Range. Backpack 

(circled) at lower center provides scale.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A15

Brooks Range, which form the structurally highest thrust slices. In the 

western Brooks Range, west of the Survey Pass quadrangle, the 

Shainin Lake Member pinches out and is generally not definable as a 

distinct member. Thus, the three members of the Kanayut cannot be 

distinguished and have not been mapped west and south of the pinchout of the Shainin Lake Member (fig. 8).

Because of its allochthonous nature, the original lateral contacts 

and facies boundaries of the Kanayut Conglomerate around the margins of its basin remain uncertain. To the north and east, the Kanayut 

probably passed gradually into coarser fluvial deposits and eventually 

thinned and lapped onto the basement that formed its provenance before thrusting; to the west and south, it probably passed laterally into 

shallow-marine and possibly deep marine deposits.

Our stratigraphic contacts for the members of the Kanayut Conglomerate, as discussed in this report, are based on detailed measured 

sections. These boundaries do not necessarily match the contacts used 

for regional l:250,000-scale mapping in the central and eastern Brooks 

Range by Brosge and others (1979a, b), who mapped the lower shale 

member (Ear Peak Member) and the Stuver Member as units composed of more than 50 percent nonresistant beds, and the middle conglomerate member (Shainin Lake Member) as a unit composed of more 

than 50 percent resistant beds (W. P. Brosge, written commun., 1981). 

Although our boundaries and those of Brosge and others (1979a, b) are 

generally similar, their middle conglomerate member is thicker than

Mk

FIGURE 7. Ridgecrest exposures of the Kanayut Conglomerate near the Atigun River. 

Dkep, Ear Peak Member; Dksl, Shainin Lake Member; MDks, Stuver Member; Mk, 

Kayak Shale. View westward.
A16 CONTRIBUTIONS TO STRATIGRAPHY

ours and encompasses strata from the upper part of the Ear Peak 

Member and the lower part of the Stuver Member as (re)defined by 

us. In the Philip Smith Mountains quadrangle, they mapped a "massive marker bed," about 200 m thick, within their middle conglomerate 

member; this unit is essentially equivalent to our Shainin Lake Member (fig. 9). West of the Philip Smith Mountains quadrangle, they did 

not map this massive marker bed within the middle conglomerate 

member but mapped the middle conglomerate member as a unit that is 

thicker than our Shainin Lake Member.

EAR PEAK MEMBER

DEFINITION

The new name "Ear Peak Member" is here applied to the previous 

informal lower shale member or lower member of the Kanayut ConSouth and 

west

 :':" /NoatakV-;:;'' ::.Vv'-.'/ -Sandstone ;.-V/.' v ;//. -^l^rrr-Trr _L

900 KILOMETERS

FIGURE 8. Schematic cross section of the Endicott Group, showing pinchout to south 

and west of the Shainin Lake Member of the Kanayut Conglomerate. Dashed lines represent timelines that indicate southwestward thinning of fluvial deposits of the 

Kanayut. Possible pinchout farther south and west of the Kanayut Conglomerate into 

marine strata is queried.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A17

glomerate; it also includes the lower part of the middle conglomerate 

member as used by Brosge and others (1979a, b). The member is 

named for exposures near Ear Peak, several kilometers east of Shainin 

Lake. The type section was measured about 1.8 km southeast of Ear 

Peak (fig. 5). "Ear Peak" is a descriptive name given by U.S. Geological Survey geologists for the peak at an elevation of 5620 ft during 

Naval Petroleum Reserve exploration in 1944; Ear Peak is situated 44 

km northeast of Anaktuvuk Pass.

The Ear Peak Member is the lowest member of the Kanayut Conglomerate, according to the new stratigraphic terminology proposed in 

this report. The Ear Peak rests gradationally on the Noatak Sandstone 

or, where the Noatak is missing (as at the type section near Ear Peak), 

directly on the Hunt Fork Shale; it is overlain conformably either by 

the Shainin Lake Member or, where absent, by the Stuver Member of 

the Kanayut Conglomerate.

The lower boundary is defined, in order of importance: by the lowest conglomerate in the Upper Devonian sequence; by the lowest conspicuous fining- and thinning-upward cycle; by the lowest black, 

brown, or red shale containing abundant plant fossils; or by the upward 

disappearance of marine megafossils or trace fossils. In most of the

REGIONAL MAPPING 

(Brosge and others, 1979a)

Kayak Shale

Conglomerate Kanayut 

Stuver Member

Middle conglomerate

<dl^^ Massive marker bed 

member

Lower shale member

Sandstone member

Hunt Fork Shale

DETAILED MEASURED SECTIONS 

(This report)

Kayak Shale

Conglomerate Kanayut 

Stuver Member

Shainin Lake Member

Ear Peak Member

Noatak Sandstone

Hunt Fork Shale

FIGURE 9. Differences in stratigraphic subdivision of the Kanayut Conglomerate in central Brooks Range, based on regional mapping and detailed measured sections.
A18 CONTRIBUTIONS TO STRATIGRAPHY

central and eastern Brooks Range, the lowest appearance of conglomerate that forms the channelized base of a sequence of thinning- and 

fining-upward cycles, averaging 5 to 15 m in thickness, can be used to 

define the base of the Ear Peak Member.

In the western and southern Brooks Range, where the Kanayut 

Conglomerate may not contain any conglomerate or where the Shainin 

Lake Member is not distinguishable, the appearance of thinning- and 

fining-upward cycles that contain sandstone in the lowest beds may be 

used to define the base of the Ear Peak Member. In other parts of the 

western and southern Brooks Range, where such cycles are not readily 

observable, it may be necessary to use the first appearance of plantbearing shale or the disappearance of marine megafossils or trace fossils to mark the approximate basal contact. In areas where the different units and this contact are both very poorly exposed, the boundary 

may have to be determined on the basis of other criteria such as lateral 

continuity from adjacent places where the basal contact is known, topographic expression (because of its coarseness, resistance to erosion, 

and internal cycles, the Ear Peak Member typically forms steplike 

ridges and ridge flanks), or color (the Ear Peak Member typically 

weathers red brown, visible especially at low sun angle, in comparison 

with the green, gray, black, or white of the underlying units).

The upper contact of the Ear Peak Member in its type section and 

throughout most of the central and eastern Brooks Range is placed at 

the top of the shale bed in the uppermost fining- and thinning-upward 

cycle below a thick sequence of more nearly massive conglomerate and 

sandstone that defines the base of the Shainin Lake Member. The Ear 

Peak Member contains abundant shale, which typically forms the 

upper parts of the cycles, whereas the Shainin Lake Member typically 

contains little or no shale. Shale intervals within the Shainin Lake 

Member are very thin and laterally discontinuous in comparison with 

those in the Ear Peak Member. The contact typically is reflected in the 

topography as a change from steplike ridge flanks to very steep, massive, nonsteplike ridgecrests (fig. 7).

AREAL EXTENT

The Ear Peak Member, which extends across almost all the eastern and central Brooks Range, forms the lowest nonmarine unit of the 

Kanayut Conglomerate (W. P. Brosge and others, unpub. data, 1982). 

We have measured sections of it as far east as the East Fork of the 

Chandalar River (sec. 10, loc. 79B-206 of Nilsen and others, 1981), 

where a thickness of 340 m for an incomplete section with neither top 

nor bottom was obtained, and along the Junjik River (sec. 11, loc. 79B136 of Nilsen and others, 1981), where a thickness of 290 m for an in-
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A19

complete section without a well-defined base was obtained below the 

Shainin Lake Member. To the west, we have measured a section at 

Iteriak Creek (sec. 12, loc. 79-B70 of Nilsen and others, 1981), where 

at least 60 m but probably much more of the Ear Peak Member underlies the Shainin Lake Member. To the west and south of Iteriak Creek, 

the Ear Peak Member is difficult to distinguish because of pinchout of 

the Shainin Lake Member.

TYPE SECTION

The type section of the Ear Peak Member of the Kanayut Conglomerate (figs. 10 and 11) was measured along the southernmost spur 

of an east-facing ridge southeast of Ear Peak, east-southeast of Shainin 

Lake (sees. 13, 24, T. 13 S., R. 5 E., and sec. 18, T. 13 S., R. 6 E., 

Chandler Lake quad.). Of the approximately 510 m of section measured, about 20 percent is covered. The section consists of 35 major fining-upward cycles that average 15 m in thickness. The entire sequence 

generally coarsens upward toward the base of the Shainin Lake Member. Cycles typically begin with 1- to 5-m-thick beds of conglomerate 

or conglomeratic sandstone, overlain by trough-cross-stratified or flatstratified sandstone that is capped in many cycles by ripple-marked 

siltstone and red shale. The base of individual cycles may be marked by 

erosional scour into the underlying unit. The amount of shale, siltstone, 

and fine-grained sandstone decreases upsection as the amount of 

coarse-grained sandstone and conglomerate increases. Plant fossils and 

rare burrows are present within beds of shale and fine siltstone in the 

lower half of the section. Marine burrows are present as high as 125 m 

above the base of the section within a thick cycle that may correlate 

with the massive marker bed of Brosge and others (1979b) in the Okokmilaga River area.

Thickness

Kanayut Conglomerate (m) 

Shainin Lake Member (lower part)

Conglomerate, massive; maximum clast size, 5 cm 0.65 

Conformable contact 

Ear Peak Member

Covered interval (rubble of conglomerate) 9.30 

Covered interval (rubble of shale, red) 9.00 

Conglomerate, parallel-stratified; maximum clast size, 6 cm; erosive 

V.OQO UAOC - - i -I-. finW

Covered interval _______________________________~__ 9 00

Sandstone oaleosol _____________________________-__ 1 50

Sandstone, medium-grained, tabular-cross-stratified .20

Conglomerate, massive; maximum clast size, 4 cm; erosive base 1.20

Sandstone, very fine grained to fine-grained, paleosol at top 1.10
A20 CONTRIBUTIONS TO STRATIGRAPHY

FIGURE 10. Measured type section of the Ear Peak Member of the Kanayut Conglomerate at Ear Peak. Dashed line denotes location of measured section. Dhf, Hunt Fork 

Shale; Dkep, Ear Peak Member; Dksl, Shainin Lake Member. View westward.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A21

Grain size

r2010 5 o'2ms5 sh

Grain size

'20 10 5 02msssh

250

-200

FIGURE 11. Type section of the Ear Peak Member of the Kanayut Conglomerate.
A22 CONTRIBUTIONS TO STRATIGRAPHY

Grain size

20 10 5 02msssh

' ' ' ' ' METERS 

 450

-400

-350

Grain size

20 10 5 02msssh

METERS

r

-500

450

i iii

FIGURE 11. Continued
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A23

EXPLANATION

Conglomerate

Conglomeratic sandstone 

Shale or siltstone rip-up clasts

Sandstone, parallel-stratified

Sandstone, trough -cross-stratified

Sandstone, tabular-cross-stratified

Epsilon cross-stratification

Siltstone and shale

\

ft

Current-ripple marks

Sand waves 

Mud cracks 

Float lithology

Fining-upward cycle 

Coarsening-upward cycle 

Paleocurrent azimuth

Burrow, invertebrate 

Plant fossil

Root cast

Paleosol

FIGURE 11. Continued

Kanayut Conglomerate Continued 

Ear Peak Member Continued

Sandstone, fine- to medium-grained, trough-cross-stratified, currentripple-laminated at top; paleosol at top 

Covered interval (probably pebbly sandstone) 

Conglomerate, parallel-stratified; maximum clast size, 7 cm 

Conglomerate, parallel-stratified, with alternating finer and coarser

grained layers; maximum clast size, 11 cm; erosive base 

Covered interval (probably shale) 

Shale and siltstone, red 

Sandstone, fine- to coarse-grained, current-ripple-laminated, with scattered pebbles; maximum clast size, 2 cm; paleosol at top 

Conglomerate, parallel-stratified; maximum clast size, 6 cm 

Interbedded conglomerate and pebbly sandstone, parallel-stratified; 

maximum clast size, 13 cm; erosive base 

Covered interval 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 

Shale, red 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm 

Conglomerate, massive; maximum clast size, 10 cm; erosive base ~ 

Covered interval (rubble of shale and siltstone, red) 

Interbedded sandstone, fine- to medium-grained, and shale, red 

1.20

1.10

6.70

12.60

1.30

4.70

7.20

1.30

18.60

9.00

3.40

.25

.30

6.00

8.60

7.10
A24 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Ear Peak Member Continued < m > 

Pebbly sandstone, coarse-grained to very coarse grained, massive;

maximum clast size, 2 cm 1.20 

Conglomerate, massive; maximum clast size, 9 cm 1.10 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 2.30 

Covered interval 7.50 

Sandstone, fine- to medium-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 1 cm 1.10 

Interbedded conglomerate and pebbly sandstone, massive to crudely

parallel stratified, maximum clast size, 6 cm 2.00 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 2.30 

Pebbly sandstone, massive; maximum clast size, 1.5 cm .20 

Conglomerate, massive; maximum clast size, 4 cm; erosive base 2.30 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

2 crn ____________________________________ 2.30 

Conglomerate, massive; maximum clast size, 4 cm; erosive base .85 

Sandstone, medium- to coarse-grained, trough-cross-stratified, with

scattered pebbles; maximum clast size, 2 cm 1.20 

Interbedded conglomerate and pebbly sandstone, crudely parallel

stratified to massive; maximum clast size, 3 cm 3.85 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 5.90 

Covered interval (probably sandstone and shale) 3.00 

Pebbly sandstone, medium- to coarse-grained, massive; maximum

dust sizf1 1 cm ___________ ____________________ 1 70 

Conglomerate, massive; maximum clast size, 1 cm; erosive base 2.20 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm; eroGl 01 \7Q v c V\Q ucioc QO . 70i v

Conglomerate, massive; maximum clast size, 1 cm; erosive base .15 

Sandstone, medium-grained to very coarse grained, trough-crossstratified ----------------------------------------------------------------------- .20

Conglomerate, massive; maximum clast size, 3 cm; erosive base .50 

Sandstone, medium- to coarse-grained, trough-cross-stratified .25 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 3.60 

Interbedded sandstone, very fine grained, and shale 2.40 

Covered interval (probably shale) 2.50 

Sandstone, fine- to coarse-grained, parallel-stratified 1.50 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm 1.50 

Conglomerate, massive; maximum clast size, 4 cm; erosive base 5.40 

Pebbly sandstone, tabular-cross-stratified; maximum clast size, 

1.5 cm .20

Conglomerate, massive; maximum clast size, 2.5 cm .05 

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified;

maximum clast size, 1.5 cm .20 

Conglomerate, massive; maximum clast size, size 2 cm .15 

Pebbly sandstone, massive; maximum clast size, 2 cm .40 

Conglomerate, massive; maximum clast size, 3 cm .20 

Pebbly sandstone, coarse-grained to very coarse grained, trough-crossstratified; maximum clast size, 3 cm .15 

Conglomerate, massive; maximum clast size, 2 cm; erosive base .05 

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified;

maximum clast size, 2.5 cm .08 

Conglomerate, massive; maximum clast size, 4 cm; erosive base .08
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A25

Kanayut Conglomerate Continued 

Stuver Member Continued

Pebbly sandstone, coarse-grained to very coarse grained, trough-crossstratified; maximum clast size, 3 cm .40 

Conglomerate, massive; maximum clast size, 4 cm; erosive base .70 

Covered interval (probably shale) 10.50 

Shale, red 6. 60

Covered interval (probably sandstone) 1.50 

Covered interval (rubble of conglomerate; maximum clast size,

g cm\ ____________________________________ 2 80

Covered interval (rubble of sandstone, fine- to medium-grained) 1.30 

Pebbly sandstone, massive, containing shale rip-up clasts; maximum

clast size, 3 cm; erosive base 4.50 

Sandstone, medium-grained, trough-cross-stratified, with scattered

plant fragments 1.30 

Sandstone, medium-grained, trough-cross-stratified, containing large

plant fragments at base 1.55 

Sandstone, medium-grained, parallel -stratified to massive, with scattered pebbles; maximum clast size, 1 cm; erosive base 1.95 

Shale and siltstone, red 1.35 

Sandstone, very fine grained to fine-grained, parallel-stratified to

trough-cross-stratified 2.00 

Sandstone, fine- to coarse-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 1.5 cm - 5.50 

Pebbly sandstone, massive; maximum clast size, 2 cm; erosive base - .95 

Sandstone, fine- to medium-grained, trough-cross-stratified 2.10 

Pebbly sandstone, massive, at base to sandstone, medium-grained,

parallel-stratified, at top; maximum clast size, 1 cm; erosive base - 2.80 

Pebbly sandstone, massive, at base to sandstone, medium-grained,

parallel-stratified, at top; maximum clast size, 2 cm 4.30 

Covered interval 3.00 

Shale and siltstone, red 6.00 

Sandstone, medium- to coarse-grained, massive, with scattered pebbles; maximum clast size, 1 cm; sharp base and top .45 

Interbedded sandstone, very fine grained, current-ripple-laminated,

Sandstone, fine- to medium-grained, parallel-stratified to trough-crossstratified 2. 75

Pebbly sandstone, massive; maximum clast size, 2 cm; erosive base - 2.35 

Sandstone, fine- to medium-grained, parallel-stratified to massive 1.20 

Sandstone, medium, trough-cross-stratified to massive 1.90 

Sandstone, medium-grained, containing epsilon cross-strata, scattered pebbles, and shale rip-up clasts at base; maximum clast size, 

1 cm ._.______ __ _..___________.__._._._._._._-_.. .95

Sandstone, fine- to medium-grained, parallel-stratified to massive; erosive base .95 

Covered interval (probably sandstone, very fine grained, parallelstratified, and shale) .85 

Sandstone, medium-grained at base to fine-grained at top, troughcross-stratified 5. 00 

Sandstone, fine- to medium-grained, trough-cross-stratified to parallelstratified . 65
A26 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Ear Peak Member Continued < m) 

Sandstone, fine-grained, trough-cross-stratified to parallelstratified __________________________________ 2.80 

Covered interval (probably sandstone) 5.00 

Covered interval (rubble of shale and siltstone, red) 15.00 

Sandstone, very fine grained to fine-grained, parallel-stratified to

trough-cross-stratified 2. 50 

Sandstone, medium-grained, trough-cross-stratified 1.65 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm; erosive

haep U<*OVP - " ^ . onC/w

Sandstone, fine- to medium-grained, trough-cross-stratified .45 

Sandstone, medium-grained, trough-cross-stratified .20 

Sandstone, fine- to medium-grained, trough-cross-stratified .40 

Pebbly sandstone to sandstone, medium-grained, at top; trough-crossstratified, containing shale rip-up clasts at bottom; maximum clast 

size, 1 cm; erosive base 2.20 

Interbedded sandstone, very fine grained, siltstone, and shale,

Sandstone, fine- to medium-grained, parallel-stratified to trough-crossstratified __________________________________ 2 50

Interbedded pebbly sandstone (maximum clast size, 2 cm) and 

sandstone, medium-grained, trough-cross-stratified 6.75

Interbedded pebbly sandstone (maximum clast size, 2 cm) and 

sandstone, medium-grained, crudely parallel statified 1.70

Interbedded conglomerate and pebbly sandstone, crudely parallel

Pebbly sandstone, trough-cross-stratified; maximum clast size,

1 5 cm ____________________________________ 50

Conglomerate, trough-cross-stratified to massive; maximum clast size,

2 cm ____________________________________ 95

Conglomerate, massive; maximum clast size, 3.5 cm; erosive base 4.00 

Sandstone, very fine grained, and siltstone 3.00 

Sandstone, very fine grained to fine-grained, parallel-stratified .60 

Sandstone, medium-grained, massive, with scattered pebbles;

maximum clast size, 1.5 cm; erosive base 1.15 

Sandstone, very fine grained, parallel-stratified to current-ripple-laminated, and siltstone, red 1.05 

Sandstone, very fine grained to fine-grained, parallel-stratified .70 

Sandstone, medium-grained, trough-cross-stratified; erosive base 1.50 

Sandstone, very fine grained to medium-grained, parallel-stratified 2.05 

Pebbly sandstone, massive; maximum clast size, 2 cm 2.15 

Covered interval (probably sandstone, fine-grained) .95 

Sandstone, fine-grained, parallel-stratified to trough-cross-

«frotifiprl _________________ 40 Dl/l dbJLLlCvl .^V

Sandstone, fine- to medium-grained, trough-cross-stratified 1.25 

Sandstone, fine-grained, trough-cross-stratified 4.25 

Sandstone, fine- to medium-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 1 cm; erosive base 4.50 

Covered interval (rubble of sandstone, very fine grained, siltstone, and

Sandstone, fine-grained, trough-cross-stratified to parallelstratified __________________________________ 2. 35
RAN AYUT CONGLOMERATE , BROOKS RANGE , ALASKA A27

Kanayut Conglomerate Continued 

Ear Peak Member Continued

Sandstone, fine-grained, trough-cross-stratified 3.00 

Sandstone, fine- to medium-grained, parallel-stratified to trough-crossstratified . 60 

Covered interval (probably sandstone, siltstone, and shale) 2.65 

Sandstone, fine-grained, parallel-stratified to trough-crossSandstone, fine- to medium-grained, trough-cross-stratified 1.55 

Sandstone, fine- to medium-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 0.5 cm .35 

Conglomerate, massive; maximum clast size, 2.5 cm .25 

Sandstone, medium- to coarse-grained, massive, with scattered pebbles; maximum clast size, 1 cm .50 

Conglomerate, massive; maximum clast size, 1.5 cm .50 

Pebbly sandstone, massive, maximum clast size, 1 cm .40 

Covered interval (rubble of conglomerate; maximum clast size,

2 cm) .30

Covered interval (probably sandstone, fine-grained, siltstone, and

oiiaic/ qhaiM - - 

- - _ ^ *J,LHJ 9^

Sandstone, fine- to medium-grained, trough-cross-stratified to current 

ripple-laminated at top, with scattered pebbles; maximum clast size, 

0. 5 cm 1 . 20

Sandstone, medium-grained to very coarse grained, massive, with scattered pebbles; maximum clast size, 1 cm at base; erosive

base 2.65

Covered interval (rubble of shale, red) .25 

Sandstone, fine-grained, trough-cross-stratified to parallel-stratified .30 

Pebbly sandstone, medium- to coarse-grained, massive; maximum clast

size, 2.5 cm; tabular-cross-stratified at base .50 

Sandstone, fine- to medium-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 1 cm .40 

Pebbly sandstone, medium-grained, trough-cross-stratified; maximum

clast size, 1 cm - - - - - .20 

Sandstone, medium-grained, trough-cross-stratified, with scattered

pebbles; maximum clast size, 2 cm 2.60 

Sandstone, medium- to coarse-grained, trough-cross-stratified to

m£LSSlVG _ ' ____________ __ _ ___ ___ _ ___ _ _ ___ _______ ______ 1 ^)

Conglomerate, massive; maximum clast size, 2 cm; erosive base .25 

Sandstone, medium- to coarse-grained, trough-cross-stratified to

massive . 10 

Conglomerate, massive; maximum clast size, 1 cm; erosive base .05 

Sandstone, medium- to coarse-grained, parallel stratified to

massive - ~ - - . 08 

Conglomerate, massive; maximum clast size, 1 cm; erosive base .10 

Sandstone, medium- to coarse-grained, massive .25 

Conglomerate, massive; maximum clast size, 2 cm; erosive base .10 

Sandstone, medium- to coarse-grained, massive .25 

Conglomerate, massive; maximum clast size, 1.5 cm; erosive base .15 

Sandstone, medium- to coarse-grained, massive; erosive base .40 

Sandstone, fine- to medium-grained, parallel-stratified, micaceous, with

scattered pebbles; maximum clast size, 0.5 cm .25
A28 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Ear Peak Member Continued (m>

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified; 

maximum clast size, 2 cm 1.45

Conglomerate, massive; maximum clast size, 2 cm .05

Sandstone, medium- to coarse-grained, massive, with scattered pebbles; maximum clast size, 1.5 cm; erosive base .55

Sandstone, very fine grained, current-ripple-laminated, micaceous; 

siltstone; and shale, red .15

Sandstone, fine-grained, parallel-stratified to current-ripple-laminated, 

micaceous . 30

Pebbly sandstone, medium-grained, trough-cross-stratified; maximum 

clast size, 1.5 cm 1.40

Sandstone, medium-grained, trough-cross-stratified, with scattered

nphVilf>« ^JVPUUICO _ - id. 9 J.V 10

Pebbly sandstone at base to sandstone, coarse-grained, massive;

maximum clast size, 2 cm; erosive base 1.00 

Covered interval .50 

Sandstone, fine-grained, parallel-stratified, micaceous, red .75 

Covered interval (probably shale) .35 

Siltstone and shale, red; paleosol at top .15 

Pebbly sandstone, parallel-stratified to massive; maximum clast size,

0.5 cm; erosive base .30 

Sandstone, fine-grained, parallel-stratified .25 

Pebbly sandstone, massive; maximum clast size, 1 cm; erosive base 1.35 

Sandstone, fine-grained, parallel-stratified to trough-cross-stratified .85 

Pebbly sandstone, massive, containing shale rip-up clasts; maximum

clast size, 0.5 cm; erosive base 3.05 

Covered interval (rubble of siltstone, current-ripple-laminated, mica -

ceous, and shale, red) .50 

Sandstone, very fine grained, current-ripple-laminated, micaceous, containing mud cracks, burrows, and plant fragments .50 

Sandstone, fine-grained, parallel-stratified to trough-crossstratified __________________________________ . 25 

Sandstone, medium-grained, trough-cross-stratified 1.15 

Sandstone, fine- to medium-grained, trough-cross-stratified 1.50 

Sandstone, medium-grained, parallel-stratified 1.15 

Sandstone, medium-grained, massive 1.05 

Conglomerate, massive; maximum clast size, 2 cm; erosive base .40 

Sandstone, fine- to medium-grained, trough-cross-stratified 1.30 

Covered interval 1.30 

Sandstone, medium-grained, massive .45 

Conglomerate, massive; maximum clast size, 1 cm; erosive base .30 

Sandstone, medium-grained at base, fine-grained at top, massive 3.00 

Sandstone, medium-grained, massive, containing abundant shale rip-up

clasts; erosive base .75 

Sandstone, very fine grained, and siltstone, current-ripple-laminated,

micaceous 1.30 

Sandstone, fine-grained, trough-cross-stratified .40 

Covered interval (probably sandstone) -80 

Sandstone, fine- to medium-grained, trough-cross-stratified .30 

Conglomerate, massive; maximum clast size, 3.5 cm; erosive base .18
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A29

Kanayut Conglomerate Continued 

Ear Peak Member Continued

Pebbly sandstone, medium-grained, trough-cross-stratified; maximum clast size, 2 cm 1.90 

Conglomerate, massive; maximum clast size, 1.5 cm; erosive base .05 

Pebbly sandstone, medium- to coarse-grained, massive; maximum clast

aiTp 1 f*TY\ ________________________________________________________________ 20

Pebbly sandstone, coarse-grained to very coarse grained, massive;

maximum clast size, 2 cm; erosive base .12 

Pebbly sandstone, crudely parallel stratified; maximum clast size,

3 cm ._.__.___ ___._._. _._______.._.._.._.________.._. 1.10

Pebbly sandstone, medium- to coarse-grained, massive; maximum clast

size, 2 cm 1.65 

Conglomerate, massive; maximum clast size, 2 cm .40 

Sandstone, medium- to coarse-grained, trough-cross-stratified, coarseenning upward .75 

Sandstone, medium-grained, trough-cross-stratified to massive 1.35 

Sandstone, fine- to medium-grained, trough-cross-stratified, with scattered pebbles; maximum clast size, 1 cm; erosive base .12 

Interbedded sandstone, very fine grained; siltstone; and shale, red, current-ripple-laminated, containing mud cracks and burrows .25 

Pebbly sandstone at base to sandstone, medium-grained at top, massive, containing shale rip-up clasts and plant fragments; erosive 

base .60 

Sandstone, coarse-grained to very coarse grained, massive, containing

plant fragments - . 10 

Conglomerate, massive, containing shale rip-up clasts; maximum clast

size, 1.5 cm; erosive base .10 

Sandstone, coarse-grained to very coarse grained, massive, with scattered pebbles . 10 

Conglomerate, massive, containing plant fragments; maximum clast

size, 2 cm; erosive base .08 

Pebbly sandstone, trough-cross-stratified at base to massive at top;

maximum clast size,l cm, coarsening upward 2.60 

Sandstone, medium-grained, trough-cross-stratified to parallelstratified 2.30

Covered interval (rubble of siltstone and shale, red) 15.65 

Sandstone, very fine grained, current-ripple-laminated; siltstone; and

shale - .40 

Sandstone, very fine grained, trough-cross-stratified .85 

Sandstone, fine-grained, massive 1.00 

Sandstone, fine- to medium-grained, trough-cross-stratified .70 

Sandstone, medium-grained, trough-cross-stratified .80 

Pebbly sandstone, medium- to coarse-grained, crudely parallel

stratified to massive; maximum clast size, 2 cm; erosive base .75 

Sandstone, very fine grained, current-ripple-laminated; siltstone,

micaceous; and shale, red .45 

Sandstone, very fine grained, parallel-stratified .20 

Pebbly sandstone at base to sandstone, medium, at top, massive;

maximum clast size, 1 cm; erosive base 1.35 

Sandstone, fine-grained, trough-cross-stratified; erosive base .50
A30 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Ear Peak Member Continued < m ) 

Conglomerate at base to sandstone, fine-grained, at top, massive;

maximum clast size, 1 cm; erosive base 1.35 

Sandstone, very fine grained to fine-grained, trough-cross-stratified .75 

Sandstone, fine- to medium-grained, massive .20 

Conglomerate, massive; maximum clast size, 1 cm; erosive base .05 

Sandstone, medium-grained, massive, containing scattered pebbles and

plant fragments; maximum clast size, 1 cm 1.20 

Conglomerate, massive; maximum clast size, 2 cm; erosive base .30 

Sandstone, medium-grained, massive at base to parallel-stratified at

top, with scattered pebbles; maximum clast size, 1 cm 1.25 

Conglomerate, massive; maximum clast size, 2 cm; erosive base .15 

Sandstone, fine-grained, trough-cross-stratified 1.00 

Pebbly sandstone at base to sandstone, fine- to medium-grained, at top, 

crudely parallel stratified; maximum clast size, 2 cm; erosive 

base .45 

Sandstone, medium-grained, massive, with scattered pebbles;

maximum clast size, 1 cm 1.15 

Pebbly sandstone, coarse-grained, parallel-stratified, containing shale

rip-up clasts; maximum clast size, 2 cm 1.00 

Sandstone, medium-grained, parallel stratified to massive, containing

abundant rip-up clasts of red shale .45 

Covered interval (rubble of shale, red, and siltstone) 2.45 

Sandstone, very fine grained, parallel-stratified to current-ripple-laminated ____________________________________ 75 

Sandstone, fine- to medium-grained, trough-cross-stratified .65 

Sandstone, very fine grained, parallel-stratified .20 

Sandstone, very fine grained, parallel-stratified .40 

Sandstone, medium-grained, trough-cross-stratified 1.10 

Sandstone, very fine grained to fine-grained, parallel-stratified, ferm2*1 nous ______________-_-__ ___-___ __ ____.».__ 30 

Sandstone, fine- to medium-grained, massive 1.70 

Covered interval 4.10 

Shale and siltstone, red 1.70 

Covered interval (rubble of sandstone, very fine grained, current-ripple-laminated, and shale) 4.50 

Sandstone, very fine grained to fine-grained, parallel-stratified to

trough-cross-stratified .90 

Sandstone, fine-grained, massive .50 

Sandstone, fine-grained, current-ripple-laminated, containing shale rip11T) cl&StS ________________________________________________________________"__________*_________"_____________"______________ 1^)

Sandstone, very fine grained, trough-cross-stratified 3.95 

Sandstone, fine- to medium-grained, trough-cross-stratified to parallelstratified, ferruginous .40 

Sandstone, fine- to medium-grained, trough-cross-stratified 1.20 

Sandstone, fine- to medium-grained, trough-cross-stratified, containing

epsilon cross-stratification .85 

Sandstone, fine- to medium-grained, massive .95 

Sandstone, fine- to medium-grained, trough-cross-stratified .25 

Sandstone, medium-grained, parallel-stratified to massive, troughcross-stratified in upper 30 cm .90 

Covered interval 3.00
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A31

Kanayut Conglomerate Continued 

Ear Peak Member Continued

Sandstone, very fine grained to fine-grained, parallel-stratified at base, 

trough-cross-stratified in middle, and current-ripple-laminated 

at top 1.45 

Sandstone, very fine grained to fine-grained, trough-cross-stratified to

current-ripple-laminated, Skolithos burrows - - .80 

Sandstone, fine-grained, massive .95 

Covered interval (rubble of sandstone, fine-grained, parallelstratified) 1.10

Sandstone, fine- to medium-grained, parallel-stratified and troughcross-stratified to massive 1.20 

Sandstone, fine- to medium-grained, massive - .95 

Covered interval (probably sandstone, fine-grained) .15 

Sandstone, fine-grained, parallel-stratified .60 

Covered interval (probably sandstone, coarse-grained) .80 

Pebbly sandstone, very coarse grained, massive, red, calcareous; erosive base .65 

Covered interval (rubble of sandstone, very fine grained, and shale, 

red) .25

Sandstone, very fine grained, parallel-stratified - .15 

Sandstone, fine-grained, parallel-stratified to massive, trough-crossstratified at top - - - - - - 1.70 

Sandstone, fine- to medium-grained, massive; erosive base .90 

Sandstone, fine-grained, parallel-stratified to trough-cross-stratified .40 

Sandstone, fine-grained, trough-cross-stratified 5.60 

Sandstone, fine-grained, massive; erosive base .50 

Covered interval (rubble of shale and siltstone, current-ripple-laminated, micaceous, brown, containing mud cracks and burrows) 2.60 

Sandstone, very fine grained, parallel-stratified, micaceous, containing

shale partings and plant fragments .20 

Covered interval (rubble of sandstone, very fine grained to finegrained, parallel-stratified) .55 

Sandstone, fine-grained, parallel-stratified .10 

Sandstone, fine-grained, parallel-stratified, containing tabular crossstrata near top .40 

Sandstone, fine-grained, trough-cross-stratified 1.95 

Sandstone, fine- to medium-grained, trough-cross-stratified .42 

Sandstone, fine-grained, trough-cross-stratified, containing shale ripup clasts in basal 3 cm; erosive base 2.70 

Sandstone, fine-grained, trough-cross-stratified 1.45 

Covered interval (probably sandstone) .30 

Sandstone, fine- to medium-grained, parallel-stratified .25 

Covered interval (probably sandstone) .35 

Sandstone, medium-grained, parallel-stratified to trough-crossstratified 2.25

Total thickness (m) 512.41

Conformable contact

Hunt Fork Shale (upper part)

Sandstone, very fine grained to fine-grained, with interbedded shale and

siltstone; sandstone is parallel-stratified to trough cross-stratified;

shale is brown to red, containing local calcareous and ferruginous

layers and abundant broken megafossil debris.
A32 CONTRIBUTIONS TO STRATIGRAPHY

The contact between the Ear Peak Member and the underlying 

Hunt Fork Shale is transitional and marked by the upward disappearance of marine megafossil debris and the initiation of distinct fining-upward cycles. The base of the first distinct fining-upward cycle (at an 

elevation of 4820 ft) forms the contact between these two units. We interpret this contact to mark the change upward from dominantly 

marine to dominantly fluvial deposition. The distinct fining-upward cycles result from lateral and vertical accretion of meandering-streamchannel and point-bar deposits. Epsilon crossbeds, which form inclined 

surfaces transecting the vertical sequences, probably represent the actual inclined surfaces of point bars within the system. The upperpoint-bar and flood-plain deposits consist of shale and ripple-marked 

siltstone, with thin interbeds of fine-grained sandstone possibly representing crevasse-splay deposition.

The clast composition approximately 320 m above the base of the 

type section is 87 percent white, gray, and black chert, 11 percent 

white quartz, and 2 percent quartzite. The clast composition 50 m 

below the base of the Shainin Lake Member consists of 82 percent 

white, gray, and black chert, 13 percent white quartz, 4 percent 

quartzite, and 1 percent argillite. The maximum clast size ranges from 

less than 1 cm near the base of the Ear Peak Member to a maximum 

of 13 cm just below the base of the Shainin Lake Member.

A total of 44 paleocurrent measurements from the type section of 

the Ear Peak Member have an azimuthal-vector mean and standard deviation of 243° ±29°. These measurements include 19 sets of trough 

cross-strata, 17 bedding surfaces with primary current lineations, two 

flute marks, two sets of tabular cross-strata, two sites of clast-longaxis orientation, and one oscillation ripple mark. Because the unidirectional indicators show southwestward sediment transport, the bidirectional indicators have been preferentially assigned a similar transport 

direction.

STRATIGRAPHIC RELATIONS

Both the lower and upper contacts of the Ear Peak Member are 

gradational and characterized regionally by interfingering with adjacent units. The basal contact with the Hunt Fork Shale or the intervening Noatak Sandstone is particularly gradational and commonly contains a sequence, as thick as 50 m, of conglomeratic fining-upward fluvial cycles alternating with more irregular cycles, locally coarsening 

upward, of marine sandstone and shale. In these transitional and 

clearly interfingering intervals, the basal contact of the Ear Peak 

Member may be difficult to pinpoint. Southward and westward, the 

Ear Peak Member essentially progrades over the underlying units and 

becomes thinner and finer grained.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A33

A conspicuous partly marine tongue of sandstone is present in the 

Ear Peak Member between the Killik River and Trans-Alaska Pipeline 

about a third of the way up its total thickness. This tongue forms a 

thick and complex cycle within a sequence of thinner, relatively simple 

fining-upward cycles characteristic of the Ear Peak Member. Although 

marine megafossils have not been found in the tongue, the presence of 

marine trace fossils of the Skolithos type, bidirectional planar crossstrata, and oscillation-ripple marks, as well as the apparent wide lateral extent of the tongue and the unusual thickness and complexity of 

the cycle, suggest an origin at least partly marine. A similar conspicuous tongue that is thick and well developed is present between the Killik and Okokmilaga Rivers in the west-central Brooks Range. Brosge 

and others (1979b) mapped this tongue as the massive marker bed of 

the lower shale member. We have measured one section in it, near the 

Okokmilaga River, where it is about 35 m thick (Nilsen and others, 

1982, fig. 13, sec. 11). These partly marine tongues may be correlative 

and may also be present in several other measured sections, including 

the type section at Ear Peak as presented herein (110-125 m above 

base of section) and a thick section adjacent to the Atigun River (405- 

420 m above base of section; Nilsen and others, 1982, fig. 4). Thus, the 

sandstone tongue may extend laterally for an overall east-west distance of as much as 200 km. This tongue evidently represents a major 

eastward incursion of the marine sea over the fluvial sequence during 

the Late Devonian.

The upper contact of the Ear Peak Member with the Shainin Lake 

Member, though typically sharp in most sections, is clearly gradational 

in others and, over a broader area, probably is interfingering. Because 

the Shainin Lake Member prograded southward and westward over 

the Ear Peak Member, tongues of the Shainin Lake Member probably 

extend southwesterly into and pinch out within the Ear Peak Member 

(fig. 8). To the west and south the Ear Peak Member is generally thinner and finer grained, whereas to the north and east it is thicker and 

coarser grained.

THICKNESS

The Ear Peak Member varies considerably in thickness from east 

to west and also from thrust plate to thrust plate. It generally appears 

to thin to the east, west, and south of the Atigun River area, where a 

thickness of 1,150 m was measured. In the eastern Brooks Range, partial thicknesses of 340 m along the East Fork of the Chandalar River 

(Nilsen and others, 1981, figs. 5A, 55, sec. 10, loc. 79B-106) and of 290 

m near the Junjik River (Nilsen and others, 1981, figs. 6A and 6B, sec. 

II, loc. 79B-136) have been measured. In the central Brooks Range,
A34 CONTRIBUTIONS TO STRATIGRAPHY

the Ear Peak Member is 510 m thick at the type section at Ear Peak, 

about 38 km west of the Atigun River. Other thicknesses measured for 

the Ear Peak Member in the central Brooks Range include: at least 40 

m in an incomplete section near Kollutarak Creek, about 12 km west 

of the village of Anaktuvuk Pass (Nilsen and others, 1980, fig. 5, sec. 

5, loc. 78B-111); 120 m near the John River; 260 m near Mount MacVicar (southeast of Chandler Lake); and 240 m near the Killik River. 

In the west-central Brooks Range, the only measured section of the 

Ear Peak Member is along Iteriak Creek, where a partial section 60 m 

thick was measured (Nilsen and others, 1981, fig. 7, sec. 12, loc. 79B70).

DEPOSITIONAL ENVIRONMENT

The Ear Peak Member was deposited almost completely in a fluvial environment, primarily by southwest-flowing meandering 

streams. The member consists of fining-upward stream-channel cycles 

consisting of conglomerate, sandstone, and siltstone, alternating with 

flood-plain deposits of shale and siltstone. Paleosols and oxidized intervals are common at the tops of the channel cycles and within the floodplain deposits.

At its base, where it interfingers with underlying marine strata of 

the Noatak Sandstone or the Hunt Fork Shale, the Ear Peak Member 

may include some shallow-marine strata, as evident in the type section, 

where marine burrows are present at the tops of some fining-upward 

cycles in the lower 50 m of the section. However, the member contains 

a conspicuous tongue of partly marine sandstone and conglomerate 

about 200 m above its base, probably deposited during a regional transgression. At its top, where it interfingers with the Shainin Lake Member, the Ear Peak Member may include some braided-stream deposits 

more typical of that unit.

AGE AND CORRELATION

The age of the Ear Peak Member is known from plant fossils found 

within it and from marine fossils in the underlying Noatak Sandstone 

and Hunt Fork Shale. Plant fossils, in the form of fragments of roots, 

branches, and stems, are locally common in the finer grained units of 

the Ear Peak Member. Plant fossils collected at two localities in the 

eastern Brooks Range indicate a Late Devonian age (Mamay, 1962; 

Brosge and Reiser, 1965; Nilsen and others, 1980). Marine megafossils 

from the upper part of the underlying marine units are upper Frasnian 

and lower Famennian. Brachiopods of Famennian age have been found 

in beds that are probably within the Ear Peak Member, about 150 m
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A35

above the base of the Kanayut Conglomerate along the upper 

Sagavanirktok River (fig. 2; Brosge and others, 1979a).

To the south and west, the Ear Peak Member overlies, partly 

grades into, and appears to be partly correlative with the underlying 

Noatak Sandstone (fig. 8). To the south and east, across the Porcupine 

River, the Ear Peak Member is separated by major faults from coeval 

units. It is correlative with the Nation River Formation of east-central 

Alaska, an Upper Devonian quartz-rich deep-sea-fan deposit (Nilsen 

and others, 1976), and with the upper part of the Imperial Formation 

of the Yukon Territory and western Northwest Territories of Canada, 

a deep-marine turbidite sequence (Martin, 1959; Norris, 1968).

SHAININ LAKE MEMBER

DEFINITION

The new name "Shainin Lake Member" is here applied to the previously informally designated "middle conglomerate member" of the 

Kanayut Conglomerate. The member is named for exposures several 

kilometers south of Shainin Lake, the area in which the type section 

was measured. Shainin Lake was named by U.S. Geological Survey 

geologists in 1951 for Vincent E. Shainin, a U.S. Geological Survey 

geologist who drowned in the lake in 1950. The lake is 37 km northeast 

of Anaktuvuk Pass; the Eskimo name for the lake is "Kanayut Lake." 

The Shainin Lake Member is the middle member of the Kanayut Conglomerate under the new stratigraphic terminology adopted in this report (fig. 4). It rests gradationally on the Ear Peak Member and is 

overlain gradationally by the Stuver Member of the Kanayut Conglomerate.

The lower boundary in the type section is defined by the basal contact of massive beds of conglomerate and sandstone with the uppermost shale interval of the series of fining- and thinning-upward cycles 

that characterizes the underlying Ear Peak Member. The Shainin Lake 

Member typically consists almost completely of alternating thick beds 

of conglomerate and sandstone, and contains little or no shale or 

siltstone. In most places, the basal contact is well defined by a topographic change from a steplike gently to steeply sloping ridge flank to 

a massive steep wall of sedimentary rocks that can be easily traced 

across the countryside. In other areas, the basal contact may be vaguer, and interbeds of shale are commonly present in what appears to 

be the Shainin Lake Member; we arbitrarily place this contact in these 

areas at the top of the highest shale interval thicker than 5 m.

The upper boundary in the type section is defined by a similar contact of massive beds of conglomerate and sandstone of the Shainin 

Lake Member below a series of fining-upward cycles that includes
A36 CONTRIBUTIONS TO STRATIGRAPHY

abundant interbedded shale. We place this upper contact at the base of 

the lowest recognizable fining- and thinning-upward cycle above the 

massive units, if well defined by a shale break, or at the base of the 

first shale interval thicker than 5 m.

AREAL EXTENT

The Shainin Lake Member extends across most of the eastern and 

central Brooks Range and eventually pinches out toward the west and 

south into the underlying Ear Peak and overlying Stuver Members 

(fig. 8). We have not distinguished it in the Mulgrave Hills, the DeLong Mountains, and adjacent areas west of Iteriak Creek (figs. 1, 2). 

West and south of where the Shainin Lake Member pinches out, the 

Kanayut Conglomerate consists of a thick sequence of fining-upward 

cycles that includes abundant shale; in these areas, the Ear Peak and 

the Stuver Member cannot be distinguished.

We have measured sections of the Shainin Lake Member as far 

west as Iteriak Creek (sec. 12, loc. 79B-70 of Nilsen and others, 1981), 

where it is about 85 m thick, and as far east as the Junjik River (sec. 

10, loc. 79B-136 of Nilsen and others, 1981), where it is 255 m thick. 

Where present, it always occupies topographically higher and steeper 

areas, and can typically be easily traced on aerial photographs and by 

aerial reconnaissance.

TYPE SECTION

The type section of the Shainin Lake Member of the Kanayut Conglomerate was measured on the prominent cliff directly south of the 

confluence of Kayak and Alapah Creeks, about 8 km south-southeast of 

Shainin Lake, in sec. 4, T. 14 S., R. 5 E., Chandler Lake quadrangle 

(fig. 5). The almost completely exposed section is 526 m thick and has 

relatively little cover (figs. 12, 13). The section is relatively uniform 

and consists of thick beds of conglomerate that fine upward into conglomeratic sandstone and medium-grained to very coarse grained 

sandstone. Shale is generally absent except for some thin intervals between 450 and 490 m above the base of the section. The coarsest and 

thickest bedded conglomerate is present in the middle part of the section, from 260 to 440 m above the base. Thinner bedded and finer 

grained conglomerate, with more abundant interbedded sandstone, 

characterizes the lower and upper parts of the section and marks the 

transitions from the Ear Peak Member and to the Stuver Member, respectively.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A37

Kanayut Conglomerate Thickness

Stuver Member (lower part)

Covered interval (rubble of conglomerate, pebbly sandstone, 

sandstone, and shale) 15.00

Conformable contact

Shainin Lake Member

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm 2.25 

Conglomerate, massive; maximum clast size, 14 cm 1.50 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm 1.20 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 3.60 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm 3.00 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 4.50 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm 1.00 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 6.80 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 3.60 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm .40 

Covered interval (probably pebbly sandstone) 4.00 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 3.25 

Pebbly sandstone, massive; maximum clast size, 3 cm .25 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 6.50 

Siltstone, parallel-laminated to massive .80 

Conglomerate, massive; maximum clast size, 4 cm; erosive base .50 

Siltstone, parallel-laminated to massive .05 

Sandstone, fine-grained, massive; paleosol .15

FIGURE 12. Measured type section of the Shainin Lake Member of the Kanayut Conglomerate south of Shainin Lake. Barbed line denotes location of thrust fault; dashed 

line denotes location of measured section. Kanayut Conglomerate: Dkep, Ear Peak 

Member; Dksl, Shainin Lake Member; MDks, Stuver Member. View southeastward.
A38 CONTRIBUTIONS TO STRATIGRAPHY

Grain size

20 10 5 Qgmss sh

METERS 

r150

-100

-50

Grain size

20 10 5 02msssh

' ' ' ' ' ' METERS -300

-250

-200

L-150

I I I I I I

FIGURE 13. Type section of the Shainin Lake Member of the Kanayut 

Conglomerate. See figure 11 for explanation of symbols.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A39

METERS 

j-450

/6^!o°c553T

&SS&

-350

300

Grain size

20 10 5 0 2n

METERS

-500

-450

FIGURE 13. Continued
A40 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness

Shainin Lake Member Continued (m)

Sandstone, fine-grained, parallel-stratified .20

Pebbly sandstone, trough-cross-stratified; maximum clast size,

15 cm ___________________________________ i jo

Siltstone, parallel-laminated to massive .20

Pebbly sandstone, trough-cross-stratified; maximum clast size, 1 cm .30

Conglomerate, massive; maximum clast size, 4 cm; erosive base 1.00

Sandstone, fine- to medium-grained, trough-cross-stratified .35

Conglomerate, massive; maximum clast size, 11 cm; erosive base 3.80

Siltstone, laminated - .10

Conglomerate, massive; maximum clast size, 12 cm; erosive base 7.20

Pebbly sandstone, massive; maximum clast size, 2 cm .40

Conglomerate, massive; maximum clast size, 6 cm 2.80

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .80

Conglomerate, massive; maximum clast size, 7 cm; erosive base 3.00

Pebbly sandstone, parallel-stratified; maximum clast size, 11 cm 1.20

Conglomerate, massive, mostly covered 4.50

Pebbly sandstone, massive; maximum clast size, 2 cm .10

Conglomerate, massive; maximum clast size, 12 cm; erosive base 2.80

Siltstone, laminated .25

Conglomerate, massive; maximum clast size, 6 cm; erosive base .60

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .10

Conglomerate, massive; maximum clast size, 8 cm; erosive base .80

Pebbly sandstone, trough-cross-stratified; maximum clast size, 3 cm 1.50

Conglomerate, massive; maximum clast size, 9 cm; erosive base 2.10

Pebbly sandstone, massive; maximum clast size, 3 cm; erosive base .25

Conglomerate, massive; maximum clast size, 9 cm; erosive base 1.65 

Pebbly sandstone, parallel-stratified to massive; maximum clast size,

g cuj ____________________________________ gg

Conglomerate, massive; maximum clast size, 12 cm; erosive base 2.50

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .40

Conglomerate, massive; maximum clast size, 12 cm; erosive base 4.50

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .20

Conglomerate, massive; maximum clast size, 13 cm; erosive base 1.50

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .25

Conglomerate, massive; maximum clast size, 21 cm 9.00

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .75

Conglomerate, massive; maximum clast size, 16 cm 5.10

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .30

Covered interval .80

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .50

Conglomerate, massive; maximum clast size, 11 cm; erosive base 9.20

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .25

Conglomerate, massive; maximum clast size, 16 cm; erosive base 12.50

Conglomerate, massive; maximum clast size, 13 cm; erosive base 4.00

Pebbly sandstone, tabular-cross-stratified; maximum clast size, 3 cm - 1.40

Conglomerate, massive; maximum clast size, 9 cm; erosive base 2.15

Pebbly sandstone, parallel-stratified; maximum clast size, 2cm .75

Conglomerate, massive; maximum clast size, 12 cm; erosive base 7.50

Pebbly sandstone, massive; maximum clast size, 4 cm .30

Pebbly sandstone, massive; maximum clast size, 1 cm .70
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A41

Kanayut Conglomerate Continued Thickness 

Shainin Lake Member Continued < m > 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 4.30 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm -- .30 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 1.90 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm -- .85 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 3.80 

Conglomerate, massive; maximum clast size, 16 cm - 6.75 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm -- .20 

Conglomerate, massive; maximum clast size, 10 cm; erosive base 2.70 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm .40 

Conglomerate, massive; maximum clast size, 15 cm; erosive base 6.20 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .70 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 1.20 

Pebbly sandstone, massive; maximum clast size, 3 cm - .25 

Conglomerate, massive; maximum clast size, 13 cm; erosive base 7.70 

Pebbly sandstone, massive; maximum clast size, 2 cm .10 

Conglomerate, massive; maximum clast size, 10 cm; erosive base .75 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .15 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 1.15 

Pebbly sandstone, parallel-stratified; maximum clast size, 1.5 cm .10 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.25 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .15 

Conglomerate, massive; maximum clast size, 5 cm .60 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm .45 

Conglomerate, massive; maximum clast size, 18 cm; erosive base 2.10 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm 1.00 

Conglomerate, massive; maximum clast size, 18 cm; erosive base 5.00 

Pebbly sandstone, massive; maximum clast size, 4 cm .10 

Covered interval - 1.00 

Conglomerate, massive; maximum clast size, 13 cm; erosive base 3.50 

Conglomerate at base to sandstone at top, parallel-stratified to massive; maximum clast size, 3 cm; erosive base .45 

Conglomerate at base to sandstone at top, massive; maximum clast

size, 4 cm .60 

Pebbly sandstone, trough-cross-stratified to parallel-stratified;

maximum clast size, 5 cm 1.75

Conglomerate, massive; maximum clast size, 12 cm; erosive base 12.00

Conglomerate, massive; maximum clast size, 11 cm; erosive base 2.10

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .05

Conglomerate, massive; maximum clast size, 11 cm; erosive base 2.25

Pebbly sandstone, parallel-stratified; maximum clast size, 7 cm .45

Conglomerate, massive; maximum clast size, 11 cm; erosive base 5.50 

Pebbly sandstone, trough-cross-stratified to parallel-stratified;

maximum clast size, 3 cm .95

Conglomerate, massive; maximum clast size, 5 cm .60

Conglomerate, massive; maximum clast size, 3 cm - .50

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm - .55

Conglomerate, massive; maximum clast size, 18 cm; erosive base 9.00

Conglomerate, massive; maximum clast size, 8 cm; erosive base - 2.20

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm - .05

Conglomerate, massive; maximum clast size, 11 cm; erosive base 1.80
A42 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Shainin Lake Member Continued (m) 

Pebbly sandstone, parallel-stratified; maximum clast size, 6 cm .90 

Conglomerate containing thin lenses of pebbly sandstone; maximum

clast size, 12 cm; erosive base - - 5.20 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm - .25 

Conglomerate, massive; maximum clast size, 1 cm .65 

Conglomerate, massive; maximum clast size, 17 cm; erosive base 7.00 

Sandstone, medium-grained to very coarse grained, parallel-stratified,

Conglomerate, massive; maximum clast size, 15 cm; erosive base 6.50 

Pebbly sandstone, trough-cross-stratified to parallel-stratified;

maximum clast size, 3 cm .25 

Conglomerate, massive; maximum clast size, 22 cm; erosive base 3.40 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 1.05 

Pebbly sandstone, massive; maximum clast size, 5 cm .60 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.20 

Sandstone, medium- to coarse-grained, parallel-stratified .25 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 1.50 

Sandstone, fine- to medium-grained, massive .20 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .20 

Pebbly sandstone, parallel-stratified; maximum clast size, 1 cm .30 

Conglomerate with interbedded pebbly coarse sandstone, parallelstratified to massive; maximum clast size, 5 cm 4.60 

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified;

maximum clast size, 3 cm .35 

Conglomerate, massive; maximum clast size, 4 cm; erosive base .45 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

12 cm ------------------------------------------------------------------------------- 2.00

Conglomerate, massive; maximum clast size, 8 cm; erosive base 3.80 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

2cm 4.25

Conglomerate, massive; maximum clast size, 9 cm; erosive base .25 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

7 cm 1. 10

Conglomerate, massive; maximum clast size, 7 cm; erosive base .50 

Pebbly sandstone, trough-cross-stratified; maximum clast size, 2 cm 1.95 

Conglomerate, massive; maximum clast size, 10 cm; erosive base .20 

Sandstone, medium-grained, parallel-stratified .15 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .25

Pebbly sandstone, trough-cross-stratified; maximum clast size, 

3 cjn ____________________________________ gg

Conglomerate interbedded with pebbly sandstone; maximum clast size,

6 cm .55 

Conglomerate interbedded with pebbly sandstone, parallel-stratified;

maximum clast size, 6 cm 2.15 

Conglomerate, massive; maximum clast size, 9 cm; erosive base .75 

Conglomerate at base to pebbly sandstone at top, parallel-stratified to

massive; maximum clast size, 7 cm 1.15 

Conglomerate interbedded with pebbly sandstone, parallel-stratified to

massive; maximum clast size, 8 cm 2.20 

Pebbly sandstone, trough-cross-stratified; maximum clast size, 3 cm .75
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A43

Kanayut Conglomerate Continued Thickness 

Shainin Lake Member Continued <m> 

Conglomerate, massive; maximum clast size, 13 cm; erosive base .65 

Conglomerate, massive; maximum clast size, 6 cm; erosive base .65 

Conglomerate at base to pebbly sandstone at top, massive; maximum

clast size, 7 cm; erosive base 1.40 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm .75 

Conglomerate, massive, reverse-graded; maximum clast size, 

13 cm ____________________________________ i gO

Sandstone, medium- to coarse-grained, trough-cross-stratified - .65 

Conglomerate, massive; maximum clast size, 8 cm; erosive base .10 

Pebbly sandstone, massive; maximum clast size, 3 cm .40 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 3.00 

Conglomerate, massive; maximum clast size, 6 cm; erosive base -- 1.10 

Pebbly sandstone at base to coarse-grained sandstone at top; maximum

clast size, 6 cm; erosive base .35 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm .45 

Conglomerate, massive; maximum clast size, 3 cm .20 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .60 

Conglomerate, massive; maximum clast size, 17 cm; erosive base 4.80 

Pebbly sandstone at base to coarse-grained sandstone at top, troughcross-stratified; maximum clast size, 2 cm - - 1.80 

Sandstone, medium-grained, trough-cross-stratified 1.80 

Covered interval (probably sandstone) 2.20 

Conglomerate, massive; maximum clast size, 13 cm 1.05 

Pebbly sandstone, parallel-stratified; maximum clast size, 

2.5 cm 1.50

Covered interval 2.00 

Conglomerate, massive; maximum clast size, 6 cm; erosive base .90 

Pebbly sandstone at base to coarse-grained sandstone at top; maximum

clast size, 3 cm; erosive base .80 

Pebbly sandstone, medium-grained, massive; maximum clast size,

1 £fJJ ________________________________________________________________________________________________________ gO

Covered interval (probably pebbly sandstone) - 1.00 

Conglomerate at base to pebbly sandstone at top, massive; maximum

clast size, 3.5 cm; erosive base 1.10 

Conglomerate at base to pebbly sandstone at top, massive; maximum

clast size, 3 cm; erosive base .75 

Pebbly sandstone, massive; maximum clast size, 2 cm 1.50 

Conglomerate, massive; maximum clast size, 4 cm; erosive base 1.80 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .40 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 4.50 

Pebbly sandstone, massive; maximum clast size, 8 cm - .45 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 1.40 

Conglomerate, massive; maximum clast size, 11 cm; erosive base 2.70 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm - 1.10 

Conglomerate, massive; maximum clast size 9 cm; erosive base - 2.70 

Conglomerate, massive, reverse-graded; maximum clast size, 12 cm;

erosive fo<iSG ____________ __ _____ ____-__~__ 2 55 

Sandstone, medium- to coarse-grained, parallel-stratified .90 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .60 

Covered interval - .20
A44 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness

Shainin Lake Member Continued < m >

Conglomerate, massive; maximum clast size, 7 cm; erosive base .85

Covered interval . 15

Pebbly sandstone, massive; maximum clast size, 2 cm .20

Conglomerate, massive; maximum clast size, 4 cm; erosive base .55

Sandstone, medium-grained, parallel-stratified .50

Covered interval (probably pebbly sandstone) 1.50

Pebbly sandstone, massive; maximum clast size, 4 cm 1.90

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.50

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .15

Conglomerate, massive; maximum clast size, 8 cm; erosive base 2.80

Conglomerate, massive; maximum clast size, 10 cm; erosive base 1.05

Pebbly sandstone, massive; maximum clast size, 7 cm .90

Conglomerate, massive, maximum clast size, 8 cm; erosive base 1.25

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm 1.10

Conglomerate, massive; maximum clast size, 6 cm; erosive base .95

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.10

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .55

Conglomerate, massive; maximum clast size, 4.5 cm; erosive base .50

Pebbly sandstone, trough-cross-stratified; maximum clast size, 1 cm .50

Conglomerate, massive; maximum clast size, 3 cm; erosive base .35

Pebbly sandstone, massive; maximum clast size, 2 cm .25

Conglomerate, massive; maximum clast size, 10 cm; erosive base 2.65

Conglomerate, massive; maximum clast size, 10 cm; erosive base 1.00

Pebbly sandstone, massive; maximum clast size, 2 cm .40

Conglomerate, massive; maximum clast size, 5 cm; erosive base .75

Pebbly sandstone, parallel-stratified; maximum clast size, 7 cm .60

Conglomerate, massive; maximum clast size, 14 cm; erosive base .95

Conglomerate, massive; maximum clast size, 9 cm; erosive base 1.45

Sandstone, medium- to coarse-grained, parallel-stratified .10

Conglomerate, massive; maximum clast size, 12 cm; erosive base 1.50

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .45

Conglomerate, massive; maximum clast size, 7 cm; erosive base .75

Pebbly sandstone, trough-cross-stratified; maximum clast size, 4 cm 1.05

Covered interval (probably conglomerate) .75

Conglomerate, massive; maximum clast size, 12 cm; erosive base 4.20

Conglomerate, massive; maximum clast size, 1 cm .85

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .55

Conglomerate, massive; maximum clast size, 10 cm; erosive base .35

Pebbly sandstone, massive; maximum clast size, 2 cm .10

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.40

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .35

Conglomerate, massive; maximum clast size, 6 cm 1.40

Conglomerate, massive; maximum clast size, 5 cm; erosive base 1.50

Pebbly sandstone, massive; maximum clast size, 3 cm .40

Conglomerate, massive; maximum clast size, 7 cm; erosive base .95 

Conglomerate at base to pebbly sandstone at top, parallel-stratified;

maximum clast size, 7 cm; erosive base 1.00

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .10

Conglomerate, massive; maximum clast size, 10 cm; erosive base 1.00
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A45

Kanayut Conglomerate Continued Thickness 

Shainin Lake Member Continued <»i> 

Conglomerate, massive; maximum clast size, 16 cm; erosive base 2.45 

Pebbly sandstone, massive; maximum clast size, 2 cm .40 

Pebbly sandstone, massive; maximum clast size, 3 cm .80 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 1.45 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .50 

Conglomerate, massive; maximum clast size, 5 cm 2.50 

Conglomerate, massive; maximum clast size, 8.5 cm; erosive base 1.60 

Pebbly sandstone, massive; maximum clast size, 2 cm .30 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.50 

Pebbly sandstone, parallel-stratified; maximum clast size, 3.5 cm .30 

Conglomerate, parallel-stratified; maximum clast size, 6 cm; erosive

base - .80 

Pebbly sandstone, massive; maximum clast size, 3.5 cm .35 

Conglomerate, massive; maximum clast size, 4 cm; erosive base 1.55 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .10 

Conglomerate, massive; maximum clast size, 5 cm; erosive base 1.35 

Pebbly sandstone, medium- to coarse-grained, parallel-stratified;

maximum clast size, 2 cm .30 

Conglomerate, massive; maximum clast size, 4 cm; erosive base 1.00 

Pebbly sandstone, medium-grained, parallel-stratified; maximum clast

size, 4 cm - .80 

Conglomerate, massive; maximum clast size, 7 cm 2.35 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

5 cm .35

Conglomerate, crudely parallel stratified to massive; maximum clast

size, 8 cm; erosive base 3.20 

Sandstone, medium- to coarse-grained, massive; paleosol at top .35 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 1.50 

Pebbly sandstone, coarse-grained, massive; maximum clast size,

1 cm .10

Conglomerate, massive; maximum clast size, 7 cm; erosive base .25 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

1 cm .35

Conglomerate, massive; maximum clast size, 8 cm; erosive base .85 

Conglomerate, massive, maximum clast size 2 cm .15 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 1.20 

Pebbly sandstone, trough-cross-stratified; maximum clast size,

2 cm _____________________________________ .35

Conglomerate, massive; maximum clast size, 12 cm; erosive base .95 

Conglomerate, massive; maximum clast size, 9 cm; erosive base .95 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.50 

Conglomerate, massive; maximum clast size, 3 cm .20 

Conglomerate, massive; maximum clast size, 15 cm; erosive base 2.50 

Pebbly sandstone, parallel-stratified to low-angle-trough-crossstratified; maximum clast size, 3 cm .40 

Conglomerate, crudely parallel stratified to massive; maximum clast

size, 9 cm; erosive base 1.70 

Pebbly sandstone, massive; maximum clast size, 2 cm 1.20 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .90 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm 1.20
A46 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness

Shainin Lake Member Continued <m>

Conglomerate, massive; maximum clast size, 14 cm; erosive base 2.60 

Pebbly sandstone, trough-cross-stratified to tabular-cross-stratified;

maximum clast size, 2 cm - - .15

Conglomerate, massive; maximum clast size, 10 cm 1.20 

Interbedded conglomerate and pebbly sandstone, parallel-stratified to

massive; maximum clast size, 7 cm; lens-shaped units 2.10

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .05

Conglomerate, massive; maximum clast size, 8 cm; erosive base .35

Pebbly sandstone, massive; maximum clast size, 3 cm .10

Conglomerate, massive; maximum clast size, 18 cm; erosive base 1.15

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .30

Conglomerate, massive; maximum clast size, 10 cm; erosive base 1.35

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .20

Conglomerate, massive; maximum clast size, 13 cm; erosive base .90 

Interbedded conglomerate and pebbly sandstone, crudely parallel

stratified to massive; maximum clast size, 12 cm .90

Conglomerate, massive; maximum clast size, 7 cm; erosive base .30

Conglomerate, massive; maximum clast size, 11 cm; erosive base .75

Conglomerate, massive; maximum clast size, 16 cm; erosive base .35

Sandstone, coarse-grained, parallel-stratified .55

Conglomerate, massive; maximum clast size, 3 cm; erosive base .25

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .25

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.20 

Interbedded conglomerate and pebbly sandstone, crudely parallel

stratified to massive; maximum clast size, 5 cm 1.40 

Pebbly sandstone, parallel-stratified; maximum clast size

2 cm --------------------------------------------------------------------------------- .10

Conglomerate, massive; maximum clast size, 4 cm; erosive base .45 

Pebbly sandstone, massive; maximum clast size, 2 cm .20 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .75 

Pebbly sandstone, massive; maximum clast size, 2 cm .25 

Conglomerate, massive; maximum clast size, 3 cm; erosive base .30 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .55 

Conglomerate, massive; maximum clast size, 13 cm; erosive base 2.95 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm 1.80 

Conglomerate, massive; maximum clast size, 15 cm; erosive base 1.70 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 3.70 

Pebbly sandstone, massive; maximum clast size, 2 cm .10 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 1.50 

Conglomerate, massive; maximum clast size, 1 cm; erosive base 1.10 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 3.40 

Pebbly sandstone, parallel-stratified to low-angle-trough-crossstratified; maximum clast size, 5 cm .25 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 2.60 

Conglomerate, massive; maximum clast size, 3 cm; erosive base .65 

Conglomerate, massive; maximum clast size, 10 cm; erosive base 1.80 

Conglomerate, massive; maximum clast size, 12 cm; erosive base 2.20 

Pebbly sandstone, massive; maximum clast size, 2 cm .10 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.50 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .50
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A47

Kanayut Conglomerate Continued 

Shainin Lake Member Continued

Pebbly sandstone, trough-cross-stratified; maximum clast size, 3 cm;

lens-shaped 2.10 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 2.00 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 1.45 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 1.20 

Pebbly sandstone, trough-cross-stratified; maximum clast size, 2 cm;

lens-shaped . 15 

Conglomerate, massive; maximum clast size, 5 cm; erosive base .55 

Pebbly sandstone, trough-cross-stratified; maximum clast size, 3 cm;

lens-shaped . 60 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.60 

Pebbly sandstone, parallel-stratified; maximum clast size, 3.5 cm .90 

Conglomerate, massive; maximum clast size, 10 cm; erosive base 3.30 

Sandstone, medium-grained to very coarse grained, parallel-stratified,

lens-shaped . 10 

Pebbly sandstone, parallel-stratified; maximum clast size, 3 cm .45 

Conglomerate, massive; maximum clast size, 6 cm; erosive base .30 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm 1.80 

Conglomerate, massive; maximum clast size, 6 cm .80 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm 1.15 

Conglomerate, massive; maximum clast size, 6 cm; erosive base 1.40 

Pebbly sandstone, parallel-stratified; maximum clast size, 2 cm .30 

Conglomerate, massive; maximum clast size, 3 cm .40 

Covered interval 3.10 

Conglomerate, massive; maximum clast size, 7 cm; erosive base .95 

Pebbly sandstone, parallel-stratified to massive; maximum clast size,

1.5 cm ___________________________________ .35 

Conglomerate, massive; maximum clast size, 6 cm; erosive base .45 

Pebbly sandstone, massive; maximum clast size, 5 cm .50 

Conglomerate, massive; maximum clast size, 6 cm; erosive base .45 

Pebbly sandstone, parallel-stratified; maximum clast size, 4.5 cm .45 

Pebbly sandstone, parallel-stratified to low-angle-trough-crossstratified; maximum clast size, 5 cm 1.25 

Conglomerate, massive; maximum clast size, 11.5 cm; erosive base .60 

Pebbly sandstone, parallel-stratified; maximum clast size, 5 cm .25 

Conglomerate, massive; maximum clast size, 7 cm .70 

Covered interval .75 

Conglomerate, massive; maximum clast size, 4 cm .35 

Covered interval .70 

Pebbly sandstone, massive; maximum clast size, 3 cm .75 

Covered interval (probably conglomerate) - 4.00 

Conglomerate, massive; maximum clast size, 9 cm; erosive base 1.20 

Conglomerate, massive; maximum clast size, 8 cm; erosive base .80 

Conglomerate, massive; maximum clast size, 7 cm; erosive base 1.15 

Conglomerate, massive; maximum clast size, 8 cm; erosive base 1.10 

Conglomerate at base to pebbly sandstone at top, massive; maximum

clast size, 8 cm; erosive base .40 

Conglomerate at base to pebbly sandstone at top, crudely parallelstratified to massive; maximum clast size, 7 cm; erosive base .90 

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm .12
A48 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Shainin Lake Member Continued (m) 

Conglomerate, crudely parallel stratified; maximum clast size, 7 cm

G1*OS1VG fosiSG ____ _____________ __*____________-_-__________-__ 70

Pebbly sandstone, very coarse grained, tabular-cross-stratified;

maximum clast size, 3 cm .65

Conglomerate, massive; maximum clast size, 9 cm; erosive base .60

Pebbly sandstone, parallel-stratified; maximum clast size, 4 cm .25

Total thickness (m) 523.27

Conformable contact

Ear Peak Member (upper part)

Covered interval (rubble of conglomerate, pebbly sandstone, 

sandstone, and shale) 10.00

The conglomerate beds typically have erosional bases, characterized by coarse conglomerate resting on finer conglomerate, conglomeratic sandstone, sandstone, or shale. The conglomerate beds 

most commonly are massive and characterized by normal size grading 

of conglomerate clasts, well-developed imbrication, and uniform clast 

long-axis orientation. The matrix consists of finer conglomerate and 

sandstone. Clast-supported conglomerate is most typical, although in 

the finer grained conglomerate and conglomeratic sandstone, matrixsupported conglomerate also is common; nowhere, however, is the 

matrix mud rich. There is no indication of sediment transport and deposition by debris flows or related processes; all the coarse-grained deposits appear to have resulted from streamflow.

The finer conglomerate typically has parallel stratification that 

commonly is crudely developed and marked by interlayering of coarser 

and finer conglomerate. Medium- and large-scale trough cross-strata 

and planar cross-strata are present in the upper parts of some conglomerate beds but are most characteristic of the conglomeratic sandstone 

and sandstone units that rest without erosional scour on the beds of 

massive conglomerate.

The fining-upward sequences of conglomerate to sandstone or 

shale average about 2 to 3 m in thickness in the lower 260 m of the section, about 7 m in the middle 180 m, and about 4 m in the upper 90 m. 

These sequences record stream deposition, most likely on a broad braid 

plain, in which braided streams transporting very coarse debris spread 

out over a broad aggrading depositional surface. There is no evidence 

for deposition by meandering streams, and no indication for the development of fining-upward point-bar cycles. The absence of significant 

thicknesses of shale indicates that extensive fine-grained flood-plain 

deposits were not formed. The massive and parallel-stratified beds of 

conglomerate probably represent longitudinal gravelbars formed on 

the braid plain. The trough- and planar-cross-stratified beds probably 

represent transverse bars and dunes as well as deposits laid down on
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A49

the downstream flanks of longitudinal bars. The thin shale intervals in 

the upper part of the section probably represent drapes of mud deposited over bars during postflooding lowering of stream levels. In most 

of the sections, these mud drapes, if deposited, were probably eroded 

away before or during deposition of the overlying bed of conglomerate. 

A total of 18 paleocurrent measurements from the type section of 

the Shainin Lake Member have an azimuthal-vector mean and standard 

deviation of 249° ± 25°. These measurements include 15 sites of clast 

long-axis orientation and imbrication, two sets of tabular cross-strata, 

and one set of trough cross-strata. Because the unidirectional indicators show southwestward sediment transport, the bidirectional indicators have been preferentially assigned a similar transport direction.

STRATIGRAPHIC RELATIONS

The basal and upper contacts of the Shainin Lake Member most 

commonly are sharply defined but locally are gradational, indicating interfingering of the massive conglomerate and sandstone with shale-rich 

fining-upward cycles of the Ear Peak and Stuver Members. The basal 

contact represents southwestward progradation of the Shainin Lake 

Member over the Ear Peak Member, and the upper contact northeastward retrogradation or retreat of the Shainin Lake Member (fig. 8).

THICKNESS

The Shainin Lake Member appears to be thickest at its type section near Shainin Lake in the central Brooks Range, where a thickness 

of 526 m was measured (fig. 13); it appears to thin eastward, westward, and southward from there. The westernmost measured section, 

at Iteriak Creek, is 85 m thick (Nilsen and others, 1981, fig. 7, sec. 12), 

and the easternmost measured section, at the Junjik River, is 255 m 

thick (Nilsen and others, 1981, figs. 65, 6C, sec. 11, loc. 79B-136). 

Other thicknesses measured in the central Brooks Range include 155 m 

near the Atigun River and 400 m along the west side of the John River. 

Incomplete measured sections of the Shainin Lake Member yield minimum thicknesses of 70 m near Kollutarak Creek (Nilsen and others, 

1980, fig. 5, sec. 5, loc. 78B-111), 305 m near Chandler Lake (Nilsen 

and others, 1980, fig. 7, sec. 7, loc. CHA), 165 m near the Anaktuvuk 

River, and 530 m near the Killik River.

DEPOSITIONAL ENVIRONMENT

The Shainin Lake Member was deposited in a fluvial environment, 

primarily by southwest-flowing braided streams. The member consists
A50 CONTRIBUTIONS TO STRATIGRAPHY

chiefly of fining-upward couplets of conglomerate and sandstone that 

are discontinuous laterally and characterized by abundant small channels. Shale is present in minimal amounts or absent. Paleosols or 

oxidized zones are present locally but are not well developed. The 

Shainin Lake Member appears to form a broad wedge- to lens-shaped 

body that is thickest in its central area and wedges out completely into 

meandering-stream deposits of the Ear Peak and Stuver Members to 

the southwest. We interpret the Shainin Lake Member to have been 

deposited on a broad braid plain during deposition of the middle part 

of the the Kanayut Conglomerate.

AGE AND CORRELATION

No age-diagnostic fossils have been recovered from the Shainin 

Lake Member. Plant fragments that are typically large single pieces 

of stems or roots are locally present. On the basis of its stratigraphic 

position, however, we believe that the member is Late Devonian, equivalent to part of the marine Famennian Stage.

The Shainin Lake Member may be correlative with and form part 

of the Noatak Sandstone of the western Brooks Range (fig. 8). It also 

correlates with, but is separated by major faults from, the Nation 

River Formation of east-central Alaska and the upper part of the Imperial Formation of the Yukon Territory and Northwest Territories of 

Canada.

STUVER MEMBER

DEFINITION

The Stuver Member of the Kanayut Conglomerate was previously 

named by Bowsher and Dutro (1957) for the uppermost part of the 

Kanayut Conglomerate. They described it, designated and measured a 

type section for it on a ridgecrest southeast of Shainin Lake, and provided some data on its areal extent, age, and correlation. The name 

"Stuver" is taken from nearby Mount Stuver, which has an elevation 

of 6220 ft and is 19 km northeast of Anaktuvuk Pass. Mount Stuver 

was named by F. G. Schrader or W. J. Peters of the U.S. Geological 

Survey in 1901 for Charles H. Stuver, a member of their field party. 

On the basis of more extensive mapping, remeasurement of the type 

section, and measurement of numerous additional sections, we herein 

redefine and rede scribe the Stuver Member. Although we retain most 

aspects of the original definition of the Stuver Member by Bowsher and 

Dutro (1957), we define (stratigraphically extend) the basal part of the
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A51

member to include part of the former middle conglomerate member of 

the Kanayut Conglomerate (see fig. 9).

The Stuver Member is the uppermost member of the Kanayut 

Conglomerate. It rests gradationally on the Shainin Lake or Ear Peak 

Member and is overlain, in most places abruptly but conformably, by 

the marine Kayak Shale. The redefined lower boundary of the Stuver 

Member in the central and eastern Brooks Range, where the unit rests 

on the Shainin Lake Member, is placed at the base of the lowest conspicuous fining- and thinning-upward cycle, if well defined by a shale 

break, or at the base of the lowest shale interval thicker than 5 m. The 

basal contact essentially represents a change upward from deposition 

of massive interbeds of conglomerate and sandstone of the Shainin 

Lake Member to deposition of fining-upward cycles consisting, in ascending order, of conglomerate, sandstone, siltstone, and shale or 

mudstone. The lower boundary in the western and southern Brooks 

Range, where the Shainin Lake Member is missing, is generally not 

recognizable, and the Ear Peak and Stuver Members cannot be differentiated.

The upper boundary of the Stuver Member is generally abrupt and 

is defined by the lowest occurrence of fine-grained quartzose sandstone 

containing marine trace fossils or megafossils, extensive small-scale oscillation-ripple markings, and flaser bedding above the uppermost fining- upward cycle of the nonmarine Stuver Member. The Stuver Member typically contains conglomerate or medium-grained to very coarse 

grained sandstone in the basal parts of its repetitive fining-upward cycles, whereas the basal sandstone member of the Kayak Shale is a finegrained quartzose sandstone overlain by black marine shale containing 

a characteristic marine megafossil assemblage. In the Atigun River 

area and several other places, the contact is gradational rather than abrupt and is contained within an interval of interbedded conglomerate 

and very fine grained sandstone with wave ripples. This interbedded 

interval forms a thick cycle at the top of the Stuver Member that has 

nonmarine plant-bearing shale below and marine megafossil-bearing 

shale above (Nilsen and others, 1982). Where the contact is clearly gradational and interfingering, we arbitrarily place it at the top of the uppermost conglomerate interval.

AREAL EXTENT

The Stuver Member extends across almost all the eastern and central Brooks Range in which the Kanayut Conglomerate has been mapped, where it forms the uppermost nonmarine deposits. We have measured sections of it as far east as the Junjik River, where a partial section 185 m thick was measured (loc. 79B-136 of Nilsen and others,
A52 CONTRIBUTIONS TO STRATIGRAPHY

1981), and as far west as Iteriak Creek, where a partial section about 

45 m thick was measured (Nilsen and others, 1981, figs. 6C, 7, loc. 79B70). West and south of Iteriak Creek, where the underlying Shainin 

Lake Member pinches out, neither we (Nilsen and others, 1982) nor 

Nelson and Grybeck (1980) have distinguished the Stuver Member 

from the rest of the Kanayut Conglomerate.

TYPE SECTION

The type section for the Stuver Member was designated and measured by Bowsher and Dutro (1957); it is about 1 km south-southeast of 

Mount Wachsmuth in sec. 16, T. 13 S., R. 5 E., Chandler Lake quadrangle (figs. 5, 14). We remeasured this type section during the 1978 

field season (Nilsen and others, 1980, fig. 6, sec. 6, loc. STU) and present it herein in graphic form, similar to the type sections of the Ear 

Peak and Shainin Lake Members (fig. 15).

Kayak Shale (lower part) Thickness 

Basal sandstone member (m)

Sandstone, very fine grained to fine-grained, with interbedded shale 

and siltstone; sandstone contains current ripple marks, interference 

ripple marks, linguoid ripple marks, wavy laminations, small-scale 

herringbone cross-strata, shale rip-up clasts, flaser bedding, and 

forms beds that are 1 to 5 cm thick; shale and siltstone form thin 

drapes over ripple-marked and wavy-laminated sandstone beds that 

are 0.1 to 2.0 cm thick; bioturbation common, particularly 

by Skolithos 13.40

Conformable contact 

Kanayut Conglomerate 

Stuver Member

Siltstone and shale, laminated to massive, reddish-black, poorly exposed 6.65

Sandstone, very fine grained to fine-grained, parallel-stratified and current-ripple-laminated, carbonaceous, with scattered plant-fossil fragments 2.25

Shale, black, laminated to massive, carbonaceous, containing scattered 

plant-fossil fragments and some plant roots in growth position 2.20

Sandstone, fine- to medium-grained at base and very fine grained to 

fine-grained at top, cross-stratified and current-ripple-laminated, 

containing abundant plant roots in growth position and scattered 

plant fragments 8.60

Covered interval (probably shale) 5.50

Pebbly sandstone, medium- to coarse-grained, massive; maximum clast 

size, 5 cm 5.00

Conglomerate, massive; maximum clast size, 13 cm 1.20

Shale and some silty very fine grained sandstone, massive, mottled, 

containing paleosols, red 1.35

Pebbly sandstone, coarse-grained, trough-cross-stratified to massive; 

maximum clast size, 1 cm .95

Conglomerate, massive; maximum clast size, 3 cm; lens-shaped .15
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A53

Kanayut Conglomerate Continued Thickness 

Stuver Member Continued <"< >

Pebbly sandstone, coarse-grained, trough-cross-stratified to massive; 

maximum clast size, 1 cm 1.05

Pebbly sandstone at base to sandstone, coarse-grained, and granule 

conglomerate at top, trough-cross-stratified; maximum clast size, 2 

cm; erosive base .60

Sandstone, fine- to medium-grained, massive .45

Sandstone, fine- to medium-grained, massive, containing scattered 

lenses of pebble conglomerate in lower part; maximum clast size, 1 

cm; paleosol at top .60

Sandstone, very fine grained, massive, mottled, pyritic; paleosol in 

part -~-~~ -~~-~-~~_-~-~~-~~ -----------__-_- ------------------- .12

Sandstone, medium-grained to very coarse grained, with scattered pebbles in lower part, pyritic; maximum clast size, 2 cm; paleosol 

at top .88

Conglomerate, massive; maximum clast size, 4 cm; erosive base .30

Conglomerate at base to sandstone, fine-grained, at top; maximum clast 

size, 3 cm; paleosol at top; erosive base 1.12

Shale and siltstone, massive, with scattered plant-fossil fragments, containing paleosols throughout, red, brown, and orange 7.80

Shale, laminated to massive, containing some paleosols and abundant 

plant-fossil fragments, black .85

Sandstone, fine-grained, laminated and current-ripple-marked; paleosol 

at top .60

I

FIGURE 14. Measured type section of the Stuver Member of the Kanayut Conglomerate 

southeast of Shainin Lake. Heavy dashed line denotes location of measured section. 

Kanayut Conglomerate: Dksl, Shainin Lake Member; MDks, Stuver Member; Mk, 

Kayak Shale; Ml, Lisburne Group. View westward. Photograph by J. T. Dutro, Jr.
A54 CONTRIBUTIONS TO STRATIGRAPHY

Grain size

15 10 5 02 mss sn METERS

120

METERS

150

L-130

FIGURE 15. Type section of the Stuver Member of the Kanayut Conglomerate. See figure 11 for explanation of symbols.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A55

Kanayut Conglomerate Continued 

Stuver Member Continued

Conglomerate, massive; maximum clast size, 9 cm; slightly

erosive base - .35 

Siltstone and sandstone, very fine grained, laminated to massive; containing scattered plant-fossil fragments - - .10 

Conglomerate, cross-stratified; maximum clast size, 10 cm;

erosive base 1.45 

Pebbly sandstone, coarse-grained, massive; maximum clast size, 4 cm;

slightly erosive base .15 

Sandstone, very fine grained, silty, laminated and locally current-ripple

laminated to massive; containing some paleosols 1.30 

Pebbly sandstone, trough-cross-stratified; maximum clast size, 2 cm .75 

Conglomerate, cross-stratified; maximum clast size, 6 cm;

erosive base - - - - - .86 

Shale, silty, massive, mottled; containing paleosols throughout, red to

brown - 3.45 

Sandstone, medium-grained, massive, pyritic, with scattered pebbles;

maximum clast size, 1 cm; paleosol at top - - - 1.40 

Sandstone, very fine grained, laminated; containing paleosols throughout, brown - - - - - - .30 

Sandstone, fine- to medium-grained, massive, pyritic; containing

paleosols throughout .25 

Conglomerate, massive; maximum clast size, 3 cm; erosive base .08 

Conglomerate at base to pebbly sandstone, coarse-grained, at top,

parallel-stratified to massive; maximum clast size, 3 cm;

erosive base - - - - - - - - .73 

Sandstone, fine- to medium-grained, massive, pyritic; containing some

paleosols - . 52 

Conglomerate, massive; maximum clast size, 8 cm; erosive base .75 

Sandstone, very fine grained to fine-grained, massive, mottled; containing some paleosols - - - - - - - 1.05 

Sandstone, fine-grained, massive; slightly erosive base .10 

Shale and siltstone, laminated to massive; containing mud cracks and

paleosols - - 

Sandstone, fine-grained, massive; paleosol at top - 

Conglomerate, massive; maximum clast size, 2 cm; slightly erosive

base - - - - - - - - - - .10 

Sandstone, medium-grained, massive; containing some paleosols .92 

Shale and siltstone, massive to laminated; containing some thin laminae

of sandstone, very fine grained, and some paleosols .68 

Sandstone, fine- to medium-grained, massive; some paleosols in

upper part - .80 

Conglomerate, massive; maximum clast size, 3 cm; strongly erosive

base .35

Shale, silty, fissile; containing minor paleosols, gray to red - .98 

Conglomerate at base to pebbly sandstone, fine grained, massive;

maximum clast size, 2 cm; erosive base .85 

Sandstone, fine-grained, at base to siltstone at top, massive; containing

some paleosols - - .82 

Shale, massive, red .05
A56 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Stuver Member Continued tmt

Sandstone, very fine grained to fine-grained, laminated to massive; containing some paleosols 1.15

Sandstone, medium-grained, massive; erosive base .55

Sandstone, very fine grained, silty, massive; containing some 

paleosols .08

Sandstone, medium-grained to very coarse grained, trough-crossstratified; erosive base - .32

Sandstone, medium-grained to very coarse grained, massive, mottled, 

pyritic; containing some paleosols .15

Conglomerate, cross-stratified to massive; maximum clast size, 4 cm; 

strongly erosive base .44

Sandstone, fine-grained, at base to siltstone at top, massive; containing 

some paleosols . 10

Sandstone, medium-grained to very coarse grained, massive; containing paleosols at top; slightly erosive base .10

Sandstone, silty to fine-grained, mottled; containing paleosols .10

Sandstone, fine- to medium-grained, trough-cross-stratified .88

Shale and siltstone, massive to laminated, locally mottled; containing 

some laminae of sandstone, very fine grained, and some 

paleosols - .10

Pebbly sandstone, coarse-grained, trough-cross-stratified, pyritic; containing some paleosols; maximum clast size, 2 cm .30

Conglomerate at base to sandstone, medium-grained, at top, troughcross-stratified; maximum clast size, 3 cm; erosive base 1.45

Siltstone. massive .05

Sandstone, medium-grained, trough-cross-stratified, pyritic, with scattered pebbles; maximum clast size, 1 cm; local paleosols .65

Sandstone, very fine grained, silty, massive, mottled; containing 

paleosols .48

Conglomerate at base to pebbly sandstone, coarse-grained, at top, 

trough-cross-stratified; maximum clast size, 2 cm; slightly erosive 

base 1.95

Sandstone, fine- to medium-grained, mottled, pyritic; containing some 

trough cross-strata and paleosols .50

Sandstone, medium-grained, trough-cross-stratified, pyritic, with scattered pebbles; maximum clast size 2 cm; some paleosols - - .80

Sandstone, medium- to coarse-grained, massive, mottled, pyritic; containing some paleosols - - .08

Conglomerate, massive; maximum clast size, 1 cm; lens-shaped .07

Sandstone, medium-grained, massive, pyritic; containing 

paleosol .05

Sandstone, fine- to coarse-grained, massive to laminated, pyritic; containing some laminae of sandstone, very coarse grained, and some 

paleosols .25

Sandstone, medium- to coarse-grained, massive, mottled, pyritic, with 

scattered pebbles; maximum clast size, 1 cm; some 

paleosols 1.35

Sandstone, medium- to coarse-grained, massive, mottled, pyritic, with 

scattered pebbles; maximum clast size, 1 cm; some 

paleosols .70
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A57

Kanayut Conglomerate Continued Thickness 

Stuver Member Continued <m)

Shale, massive, mottled, gray - .20

Sandstone, medium-grained, parallel-stratified to massive, locally mottled, pyritic; containing some paleosols .98

Conglomerate, massive; maximum clast size, 5 cm; erosive base 2.40

Covered interval - - - - - 14.10

Shale and siltstone, massive; containing some paleosols, red to buff; 

poorly exposed 9.10

Conglomerate at base grading upward to sandstone, fine-grained; 

maximum clast size, 3 cm; massive at base to laminated and currentripple-marked at top; paleosol at top - 6.60

Shale and siltstone, massive; containing paleosols; poorly exposed 13.50

Conglomerate at base grading upward to sandstone, very fine grained, 

at top; maximum clast size, 2 cm; parallel-stratified to massive, 

poorly exposed - - - - 9.60

Siltstone and shale, massive, mottled; containing paleosols, red and 

brown; poorly exposed 1.95

Sandstone, fine-grained; containing some trough cross-strata; poorly 

exposed - - - - - - 5.60

Sandstone, very fine grained, silty, thinly stratified to laminated, current ripple-marked, micaceous; with plant roots in place - 2.05

Shale and siltstone, massive, mottled; containing paleosol, red 1.00

Siltstone and sandstone, very fine grained, massive, brown; containing 

paleosol .28

Shale and siltstone, massive, mottled; with plant roots in place; containing paleosol, red .63

Siltstone and sandstone, very fine grained, massive; poorly 

exposed - - - - - 1.35

Shale and siltstone, massive, mottled; with plant roots in place; containing paleosol, red - - - 3.35

Siltstone, massive, mottled; containing paleosol, red, brown, 

and orange - 1.98

Interbedded very fine sandstone and siltstone, laminated, current-ripple-marked, carbonaceous; containing mud cracks and abundant fossil-plant fragments - - 2.45

Pebbly sandstone, trough-cross-stratified to massive; maximum clast 

size, 5 cm; strongly erosive base; poorly exposed 10.00

Siltstone and sandstone, very fine grained, laminated; containing mud 

cracks, micaceous, brown - .85

Conglomerate and sandstone, very coarse grained, parallel-stratified to 

massive; maximum clast size, 4 cm; erosive base - - - 4.50

Siltstone and shale, massive, brown .42

Sandstone, very fine grained to fine-grained, laminated and currentripple-marked; containing mud cracks, micaceous .53

Sandstone, medium-grained to very coarse grained, trough-crossstratified; with scattered pebbles; maximum clast size, 1.5 cm 3.80

Pebbly sandstone, coarse-grained to very coarse grained, trough-crossstratified; maximum clast size, 3 cm 3.65

Covered interval (scattered fragments of conglomerate and sandstone, 

medium- to coarse-grained) 10.90
A58 CONTRIBUTIONS TO STRATIGRAPHY

Kanayut Conglomerate Continued Thickness 

Stuver Member Continued ( > 

Interbedded sandstone, very fine grained to fine-grained, siltstone, and 

shale, laminated to massive; containing paleosols; with plant roots in 

place, micaceous; containing pyrite nodules, red 2.05 

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified;

maximum clast size, 3 cm .78 

Conglomerate, massive; maximum clast size, 3 cm; lens-shaped .10 

Pebbly sandstone, medium-grained to very coarse grained, troughcross-stratified; maximum clast size, 2 cm 2.50 

Pebbly sandstone, medium-grained, trough-cross-stratified; maximum

clast size, 3 cm 1.50 

Conglomerate, massive; maximum clast size, 7 cm; lens-shaped .20 

Pebbly sandstone, medium- to coarse-grained, trough-cross-stratified;

maximum clast size, 4 cm - 2.50 

Covered interval (probably conglomerate) 7.10 

Shale, massive, red, mostly covered .30 

Pebbly sandstone, coarse-grained, at base to sandstone, fine-grained, 

at top, trough-cross-stratified to massive; maximum clast size, 3 cm; 

poorly exposed 5.45 

Covered interval - - .90 

Shale, locally silty, massive, carbonaceous; containing fossil-plant fragments, black - .83 

Covered interval - - .75

Total thickness (m) -- 217.38

Conformable contact 

Shainin Lake Member

Conglomerate, massive

The type section as measured by us is 217 m thick, in comparison 

with the thickness of 287 m measured by Bowsher and Dutro (1957). 

The section of Bowsher and Dutro (1957, p. 11-13, pi. 3) includes a 

covered interval at its base of 43 m, whereas our section begins at the 

first conspicuous exposed interval of shale. Measurement of much of 

the section down steeply dipping slopes probably also contributed to 

the differences in thickness. The Stuver Member consists of 14 finingand thinning-upward cycles that average about 16 m in thickness. 

Shale, including most covered intervals, composes about 95 m of the 

section, or 40 percent of the thickness of the Stuver Member. Almost 

all these cycles begin with conglomerate that has an erosional basal 

contact with shale. The conglomerate grades upward through crossstratified sandstone into current-ripple-marked fine-grained sandstone 

and siltstone and, at the top, shale containing locally abundant 

paleosols. The shale is most typically black and contains abundant plant 

fossils but also includes shale with red, orange, yellow, and maroon colors, probably developed under varying conditions of oxidation.
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A59

The fining-upward cycles are thicker and better defined in the 

lower part of the Stuver Member, which contains sequences of shale as 

thick as 20 m or more. In the interval from 130 to 170 m, these cycles 

are poorly defined, and the Stuver Member consists of repetitively interbedded conglomerate and sandstone similar in appearance to the 

Shainin Lake Member; deposition by braided streams may have become dominant again within this interval. The uppermost 50 m of the 

Stuver Member is relatively fine grained and consists mostly of 

sandstone and shale. This uppermost interval, however, contains the 

coarsest clasts in the Stuver, as large as 13 cm, at the base of a finingupward cycle about 200 m above the base of the Stuver Member.

Five paleocurrent measurements from the type section of the 

Stuver Member have an azimuthal vector mean and standard deviation 

of 249° ± 25°. These measurements were taken primarily from sites of 

clast long-axis orientation and imbrication in coarse-grained conglomeratic and cross-stratified sandstone units. Because regional unidirectional indicators in the Stuver Member show southwestward sediment transport, the bidirectional indicators have been preferentially 

assigned a similar transport direction.

The upper contact of the Stuver Member with the basal sandstone 

member of the Kayak Shale is well defined. Marine trace fossils, herringbone cross-strata, reactivation surfaces, oscillation ripple marks, 

flaser bedding, absence of plant fossils, conglomerate, or paleosols, and 

the presence of very fine grained, well-sorted quartzose sandstone 

suggest marine deposition, probably under tidal conditions, for the 

basal part of the Kayak.

STRATIGRAPHIC RELATIONS

The lower boundary of the Stuver Member is marked by an upward change from outcrops of massive beds of conglomerate, 

sandstone, and little or no shale of the Shainin Lake Member to finingand thinning-upward cycles of conglomerate, sandstone, siltstone, and 

shale that characterize the Stuver Member. The basal contact may be 

either sharp or gradational. We place this contact at the base of the 

first well-defined fining-upward cycle that contains appreciable shale or 

at the base of the first shale interval thicker than 5 m.

The upper contact marks the onset of marine transgression over 

the fluvial deposits of the Kanayut Conglomerate. Although westwardthinning tongues of conglomerate may mark this transition locally (fig. 

8), it is generally marked by an abrupt change in grain size from conglomerate-bearing fining-upward cycles to very fine-grained ripplemarked sandstone of the basal sandstone member of the Kayak Shale.
AGO CONTRIBUTIONS TO STRATIGRAPHY

THICKNESS

The Stuver Member varies considerably in thickness from east to 

west and from thrust plate to thrust plate. In general, it is thin along 

the north margin of the Brooks Range, from west of the Itkillik River 

to west of the Killik River. This area includes the type section of 

Bowsher and Dutro (1957) in the Shainin Lake area, where the Stuver 

Member is about 217 m thick. East of the Itkillik River, the Stuver 

Member thickens greatly and reaches a maximum measured thickness 

of 1,310 m along the Atigun River (Nilsen and others, 1982, fig. 6, sec. 

3). East of the Atigun River, we measured a partial thickness of about 

185 m along the Junjik River (Nilsen and others, 1981, fig. 6C, sec. 11, 

loc. 79B-136). In the central Brooks Range, we measured thicknesses 

of 250 m at Chandler Lake (Nilsen and others, 1981, fig. 7, sec. 7, loc. 

CHA), of 165 m west of the John River, and of 160 m near the Okokmilaga River. In the west-central Brooks Range, we measured only an 

incomplete thickness of about 45 m of the Stuver Member along Iteriak 

Creek (Nilsen and others, 1981, fig.7, sec. 12, loc. 79B-70).

DEPOSITIONAL ENVIRONMENT

The Stuver Member was deposited in a fluvial environment, 

primarily by southwest-flowing meandering streams. The member consists of fining-upward stream-channel cycles of conglomerate, 

sandstone, and siltstone, alternating with floodplain deposits of 

siltstone and shale. Paleosols and oxidized intervals are present at the 

tops of the channel cycles, within the flood-plain sequences, and, locally, within channel fills. Plant fossils are common and are most abundant and well preserved in floodplain shale of the upper part of the 

Stuver Member.

The Stuver Member locally contains some coarse-grained deposits 

that appear to be more characteristic of braided-stream deposits. 

These units are most common in the lower part of the Stuver Member 

but may also be present in other intervals, as in the type section. The 

upper contact with the Kayak Shale, as in the section near the Atigun 

River, may locally consist of interbedded marine and nonmarine deposits that represent interfingering of these two depositional environments.

AGE AND CORRELATION

The age of the Stuver Member can be determined on the basis of 

its plant fossils and on its stratigraphic relations with overlying and underlying fossiliferous marine strata. Plant fossils from most of the 

Stuver Member indicate a Late Devonian age (Bowsher and Dutro,
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A61

1957; Porter, 1966). However, at a few localities between Shainin Lake 

and Iteriak Creek, as well as at some localities in the western Brooks 

Range (I. L. Tailleur, written commun., 1982), species indicative of an 

Early Mississippian age have been identified (S. H. Mamay, written 

communs., 1976, 1979). At most of these localities, the plant fossils are 

in beds at the top of the Stuver Member, but at one locality between 

Shainin Lake and Anaktuvuk Pass, species indicative of a possible 

Early Mississippian age have been identified from beds in the lower 

part of the Stuver (S. H. Mamay, written communs., 1979, 1980; 

Nilsen and others, 1980).

Marine megafossils from the lower part of the overlying Kayak 

Shale indicate an Early Mississippian age for that unit (J. T. Dutro, 

Jr., written communs., 1980, 1981; Nilsen and others, 1980). However, 

the oldest stage represented by the Kayak is late Kinderhookian, an 

age permitting the youngest part of the Stuver Member to be early 

Kinderhookian. Until more convincing paleontologic information is 

presented, we prefer to consider the Stuver Member as Late Devonian 

(late Famennian) and Early Mississippian(?) in age.

The Stuver Member is probably correlative with, but separated by 

major faults from, the Nation River Formation of east-central Alaska 

and the upper part of the Imperial Formation of the Yukon Territory 

and Northwest Territories of Canada.

KAYAK SHALE

The marine Kayak Shale stratigraphically overlies the Stuver 

Member of the Kanayut Conglomerate in the central and eastern 

Brooks Range. In the western Brooks Range, in the Mulgrave Hills 

area, Nilsen and Moore (1982) recognized the Kayak Shale resting on 

the Kanayut Conglomerate. The Kayak there forms a sequence of 

marine strata that onlaps the Stuver Member as a result of a northward and eastward marine transgression during the Early Mississippian that followed southwestward progradation of the fluvial Kanayut 

Conglomerate. The type locality of the Kayak Shale is on Mount 

Wachsmuth, about 2 km east of Shainin Lake (fig. 5), where the unit 

is about 320 m thick.

At the type locality the Kayak was informally divided into five 

members, in ascending order: (1) A basal sandstone member, 44 m 

thick; (2) a lower black shale member, 198 m thick; (3) an argillaceous 

limestone member, 27 m thick, (4) an upper black shale member, 47 m 

thick; and (5) a red limestone member, 4 m thick (Bowsher and Dutro, 

1957). The three lower members can be traced across most of the 

north-central Brooks Range, where they are of approximately the
A62 CONTRIBUTIONS TO STRATIGRAPHY

same thickness (Nilsen and others, 1980). Extensive tectonic transport 

through and over the Kayak Shale, however, has locally affected the 

thicknesses of some of these members, particularly the lower black 

shale member. The argillaceous limestone member contains a varied 

assemblage of brachiopods, bryozoans, echinoderms, mollusks, and ostracodes of Early Mississippian (late Kinderhookian) age. The Kayak 

Shale grades upward into massive platform limestone of the Lisburne 

Group.

SUMMARY AND CONCLUSIONS

In this report, we redefine (stratigraphically restrict) the Kanayut 

Conglomerate, redefine (stratigraphically extend) its Stuver Member, 

formally name its lower and middle members, and describe the areal 

extent, thickness, stratigraphic relations, type sections, depositional 

environments, age, and correlation of these three members with units 

that are geographically close. The former, informally designated (basal 

marine) sandstone member is here reassigned to the Noatak 

Sandstone. The former, informally designated lower shale and middle 

conglomerate members of the Kanayut are here formally named the 

Ear Peak Member and the Shainin Lake Member, respectively; and 

the redefined Stuver Member remains the uppermost member of the 

Kanayut Conglomerate. As thus redefined, the Kanayut Conglomerate 

is almost wholly nonmarine and consists of three members deposited 

mainly by fluvial processes.

The three type sections for the respective members of the 

Kanayut Conglomerate are in the Shainin Lake area of the central 

Brooks Range, as is that of the overlying Kayak Shale. The type section of the Noatak Sandstone is in the western Brooks Range, as defined by Dutro (1952, 1953a, b).

The three members of the Kanayut Conglomerate can be mapped 

and traced across most of the central and eastern Brooks Range in the 

many thrust plates that constitute its outcrop extent (W. P. Brosge 

and others, unpub. data, 1982). In the western Brooks Range the 

Shainin Lake Member, the coarsest grained unit of the Kanayut Conglomerate, pinches out toward the west and south into a continuous sequence of finer grained fluvial deposits in which the Ear Peak and 

Shainin Lake Members cannot be distinguished.

The Kanayut Conglomerate was deposited as the result of a major 

progradation of coarse-grained fluvial deposits to the southwest over 

finer grained marine deposits. The Shainin Lake Member represents 

the coarsest outbuilding of this prograding system. This member was 

deposited on a braid plain of great lateral extent. After the maximum 

pulse of progradation, the fluvial wedge of sediment retreated and was
KANAYUT CONGLOMERATE, BROOKS RANGE, ALASKA A63

eventually overlapped by a transgressing sea in which finer grained 

marine sediment and, eventually, platform carbonate sediment was deposited. Thus, the Kanayut Conglomerate represents the outbuilding 

of a very large and coarse-grained dominantly fluvial delta. Its original 

position before thrusting, and its source area, remain speculative because of problems related to palinspastic reconstructions of the depositional system (Nilsen, 1981).

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