Gubik Formation of 

Quaternary Age in 

Northern Alaska

EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4 

AND ADJACENT AREAS, NORTHERN ALASKA, 1944-53

PART 2. REGIONAL STUDIES

GEOLOGICAL SURVEY PROFESSIONAL PAPER 302-C

Prepared and published at the request of and in 

cooperation with the U.S. Department of the Navy, 

Office of Naval Petroleum and Oil Shale Reserves

Gubik Formation of 

Quaternary Age in 

Northern Alaska

By ROBERT F. BLACK

EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4 

AND ADJACENT AREAS, NORTHERN ALASKA, 1944-53

PART 2. REGIONAL STUDIES

GEOLOGICAL SURVEY PROFESSIONAL PAPER 302-C

Prepared and published at the request of and in 

cooperation with the U.S. Department of the Navy, 

Office of Naval Petroleum and Oil Shale Reserves

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1964
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington, D.C., 20402
CONTENTS

Abstract _ _ _________________________

Introduction. ________________________

Acknowledgments ___ _ _______________

Geography and geology __ ____________

Gubik Formation. ____________________

History __ ______________________

Mineralogy ______________________

Fossils ___ ______________________

Subdivision of the Gubik Formation. 

Skull Cliff unit_______________

Locality descriptions ______

Skull Cliff________.__

Drew Point. _________

Mitlitavik_ __________

Nunavak. __________

Christie Point_______

Meade River unit _ _________

Locality descriptions _____

Sentinel Hill. __ _____

Topagoruk _ _______

Central Coastal Plain 

Mitlitavik_ _________

Atigaru Point _______

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Gubik Formation Continued

Subdivision of the Gubik Formation Continued 

Meade River unit Continued

Locality descriptions Continued

Ikpikpuk_ _________________________

Admiralty Bay______-_____-_------_

Ocean Point______________________

Meade River.______________________

Kikiakrorak_ _____________________

Barrow unit______________________________

Locality descriptions.___________________

Skull Cliff.-____-_-_-_-__-_----_-_-

Walakpa__ ______________________

Nunavak._________________________

Christie Point._____________________

Barrow.___________________________

Teshekpuk__ _ ______________________

Peard Bay_-___-._________-_-----__

Cape Simpson______________________

Age and correlation of the Gubik Formation.______

Geomorphic history of the Gubik Formation.______

Engineering significance of the Gubik Formation _ 

References cited.___________________________________

ILLUSTRATIONS

FIGURE 9. Index map of northern Alaska.-------------------------------------------------------------------

10. Distribution of Quaternary fossils__________________---____--_---_----------_--------------------

11. Sketch map of the Barrow area______________________-______-----___----------------------------

12. Coastal bluff 1.5 miles northeast of Walakpa_--____----_----_--_-----------------------------------

13. Skull Cliff unit of the Gubik Formation showing ice__-___-_-___--------_-------_-----_--_-----------

14. Size-grade cumulative curves of the Skull Cliff unit of the Gubik Formation from Drew Point area-------

15. Size-grade cumulative curves of the Skull Cliff unit of Gubik Formation from Kokolik River, Admiralty 

Bay, Walakpa, Christie Point, and Nunavak-_____-_____________-____----_--__-------------------

16. Ice in marine clay-silts of the Skull Cliff unit of the Gubik Formation below and lacustrine deposits with peat 

above ____-____________________________________-___________-------------____-----_---_-------

17. Sand of Meade River unit of the Gubik Formation___________________________________-_-----------

18. Sandy clay-silt of the Meade River unit of the Gubik Formation._____________-______-_--------------

19-23. Size-grade cumulative curves of the Meade River unit of the Gubik Formation from:

19. Sentinel Hill.___________________________________________________________ 

20. Topagoruk River____________________________________________-_-___-------_--------------

21. Central part of the coastal plain and Ikpikpuk__ -________________---___--_----_---------------

22. Vicinity of Mitlitavik. _ _ _ ____________________________________________ _______-_-----

23. Admiralty Bay and Atigaru Point____._____________________-___---___-----------------------

24. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Walakpa-----------------

25. Lacustrine deposits over fluvial(?) deposits__________________-__--__-__------_--------------------

26. Part of the Barrow unit of the Gubik Formation at Nunavak- _______________________------_---------

27-29. Size-grade cumulative curves of the Barrow unit of the Gubik Formation:

27. From Nunavak and Christie Point._____________________-__-_-___------_--------------------

28. Barrow area, from airbase ice cellar.__________-____-___-__-____-__-_-----------------------

29. Barrow area, from drill cores_--________________-_-_____---_-----------_---------------------

30. Diagrammatic cross section through an uplifted bar________________-_____---_---------------------

31. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Teshekpuk Lake.---------

32. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Peard Bay.--------------

in

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EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4 AND ADJACENT AREAS,

NORTHERN ALASKA, 1944-53

GUBIK FORMATION OF QUATERNARY AGE IN NORTHERN ALASKA

By EGBERT F. BLACK

ABSTRACT

The unconsolidated Gubik Formation of Quaternary age 

unconformably mantles rocks of Cretaceous or Tertiary age 

throughout the Arctic coastal plain province of northern Alaska. 

Data from many geologists of the U.S. Geological Survey, working in Naval Petroleum Reserve No. 4, are summarized, and the 

Gubik Formation in the coastal plain west of the CoMlle River 

is described. There, the Gubik consists largely of lenses and 

admixtures of silt and fine-grained sand in which quartz and 

chert predominate. Clay and gravel are lesser constituents. 

Accessory minerals are estimated to total less than 10 percent. 

The sediments are dominantly marine and are characterized by 

calcareous shallow-water invertebrate faunules much like those 

living along the coast today. Terrestrial vertebrate remains 

are sparse but widespread. Fluvial, lacustrine, eolian, and frost 

processes are also involved in the deposition or modification of 

the Gubik sediments.

The three main lithologic units are distinguished as follows: 

Skull Cliff unit oldest; commonly consists of poorly sorted 

clay- to cobble-size sediment; commonly sticky or greasy; 

blue black to dark gray; mostly marine, but part may be 

glacially derived; deposited unconformably on Cretaceous 

rocks west of the Colville River; observed maximum thickness 

is 20 feet; poorly exposed.

Meade River unit intermediate; consists of clean light-colored 

well-sorted quartz sand; mostly marine, but locally lacustrine 

and eolian; generally unconformable on Skull Cliff unit, but 

locally unconformable on Cretaceous bedrock and conglomeratic at base; especially loesslike in the southern and southeastern parts of the coastal plain; maximum thickness 

approaches 200 feet.

Barrow unit generally youngest but in part contemporaneous 

with Meade River unit; consists of poorly sorted to wellsorted mixtures of clay, silt, sand, and gravel; color grades 

from light to dark; generally marine at base, but lacustrine 

and fluvial deposits characterize uppermost sediments; part 

may be glacially derived; ice locally constitutes more than 

half the volume; organic matter abundant in upper part; 

rarely deposited unconformably on the Cretaceous rocks; 

generally interfingers with the Meade River unit; a few tens of 

feet thick.

The Gubik represents a shallow near-shore shelf environment, 

in which frequent shifting of the strandline has occurred. Fossils collected do not pinpoint the age of any part of the Gubik 

but suggest that it may represent all the Pleistocene and part 

of the Pliocene. The sequence of deposition of the three lithologic units, as interpreted by the writer, agrees with the paleontologic sequence, but on the basis of the geomorphic evidence,

the deposition of the three units did not require all the Pleistocene and late Pliocene. Only part of the Pleistocene is needed, 

but available data are insufficient to negate the paleontologic 

correlation. The geomorphic evidence consists of modification 

of geomorphic features, carbon-14 dates, archeologic findings, 

and growth rate of ice wedges. The Barrow unit, according to 

carbon-14 dates, must represent much, if not all, of the Wisconsin Glaciation. The Meade River unit then might be correlated 

with the Sangamon Interglaciation, and the Skull Cliff unit with 

the Illinoian Glaciation.

The geomorphic history of the Gubik is exceedingly complicated in detail and cannot be reconstructed now except in 

gross outline. The Arctic coastal plain is not a single plain 

but a number of surfaces of erosion and deposition in which 

uplift has not been uniform in either time or place. Warping 

of shore lines as high as 600 feet in elevation is recognized. 

Moreover, subaerial processes now affecting the Gubik seemingly 

did not all act with present intensity, if indeed they acted at 

all, during the brief emergences of the coastal plain during 

deposition of the Gubik. Conditions favorable for growth of 

ice wedges cannot be traced back much beyond 10,000 years 

without a break. Cold climates and the presence of permafrost, however, are recognized during the deposition of the 

upper 20 feet at least of the Barrow unit a time apparently 

encompassing several tens of thousands of years. Apparently, 

too, the Skull Cliff unit, which is in part composed of glacial 

detritus, was laid down under similar conditions. In contrast, 

the Meade River unit was well winnowed by marine waters 

and modified extensively by wind action. No evidence of synchronous glaciation or cold climates has been recognized.

The Gubik Formation does not in itself produce unusual 

problems in engineering, but the fact that the material is 

perennially frozen and generally contains more ice than pore 

space is of great engineering significance.

INTRODUCTION

The unconsolidated Gubik Formation of Quaternary 

age unconformably mantles consolidated rocks of Cretaceous and of Tertiary age throughout the Arctic 

coastal plain province of northern Alaska (fig. 9), and 

widespread deposits of equivalent age are reported in 

northwestern Canada (MacKay, 1959; MacNeil, 1957). 

Although economic incentive for study of the Gubik 

Formation has been lacking, many geologists of the U.S. 

Geological Survey, working on projects in and adjacent 

to Naval Petroleum Eeserve No. 4 during 1944-53, have
60 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

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GUBIK FORMATION IN NORTHERN ALASKA 61

amassed much data on the nature and distribution of 

the Gubik Formation. These data have largely gone 

unrecorded or unassimilated in the published literature 

on northern Alaska. During the writer's studies of 

permafrost and geomorphology in northern Alaska, 

1945-50, numerous brief observations were made of the 

Gubik Formation west of the Colville River, and the 

formation was subdivided into three lithologic units. 

In 1953 the writer compiled a summary of the observations made by him and by other personnel of the Geological Survey. In 1959 the writer used this summary 

to prepare the present paper without recourse to further field or laboratory work. This paper thus summarizes the available knowledge of the Gubik Formation west of the Colville River as of about 1950, although some of the more recent literature is cited.

Observation and sampling by the writer were made as 

time permitted, and detailed field studies of the Gubik 

Formation were not attempted. The writer collected 

255 samples from various places in the coastal plain west 

of the Colville River, of which 147 have been analyzed 

mechanically. The grade scale of the National Research Council (1947) was used for textural classification. Each sample was examined under a binocular 

microscope. Some samples were checked with index 

oils and a petrographic microscope; however, no separations were attempted of light and heavy minerals, nor 

were detailed studies of mineralogy or paleontology 

made.

Planimetric maps at 1: 48,000 scale provided the base 

for location of samples. Maps at 1: 250,000 scale containing contours of 20-, 50-, or 100-foot intervals were 

available after the field studies were completed. Vertical aerial photographs of 1:20,000 scale reproduce all 

the coastal plain. Access to these maps and photographs, however, was very limited during the field 

study, and they have not been examined subsequently 

except in local areas. Consequently, known details of 

the Gubik Formation are limited to local areas or sections, and only broad generalizations subject to revision, 

are now attempted.

ACKNOWLEDGMENTS

The writer is indebted particularly to those U.S. 

Geological Survey personnel, referred to later in the 

text, from whom data on the Gubik Formation were obtained. The writer's knowledge of the Gubik was 

gained while making permafrost studies for the U.S. 

Geological Survey which, during 1949-50, were conducted in cooperation with the Office of Naval Research. 

During the summers of 1946 and 1947, limited observations were made at widely scattered points on the coastal 

plain west of the Colville River, utilizing float planes

provided by the U.S. Navy and the U.S. Coast and Geodetic Survey. The coast for .100 miles southeast of 

Barrow and 40 miles southwest of Barrow was examined 

from small boats or on foot. Travel in the immediate 

vicinity of the naval airbase, 4 miles northeast of Barrow village and 6 miles southwest of Point Barrow, was 

accomplished mostly on foot, but weasels (amphibious 

tracked personnel carriers, M 29 C) were used during 

1949-50 at the courtesy of the Arctic Research 

Laboratory.

Some logs of well drillers of Arctic Contractors 

(Reed, 1958, p. 34) were used in this study. Where used 

directly, such data are credited to the source. Mechanical analyses of samples were made by the writer, the 

U.S. Department of Agriculture, the St. Paul District 

Engineers Permafrost Research Laboratory, and the 

Rock Island Corps of Engineers, U.S. Army.

GEOGRAPHY AND GEOLOGY

Although the Gubik Formation occurs throughout 

the Arctic coastal plain province, the northernmost 

physiographic province in Alaska, only the part of the 

formation west of the Colville River was studied by the 

author. This area (fig. 9) includes most of the Teshekpuk Lake section (Payne and others, 1951). The White 

Hills section of the Arctic coastal plain, lying entirely 

east of the Colville River, is not included in the study 

area.

The Arctic coastal plain and the Arctic foothills 

(formerly the Anaktuvuk Plateau of Schrader, 1904, 

and the Arctic Plateaus of Smith and Mertie, 1930) 

constitute the Arctic Slope of Brooks (1906). The 

Arctic coastal plain is a flat, generally featureless plain, 

roughly triangular in shape, that extends from Cape 

Beaufort on the west to the International Boundary on 

the east. It reaches its maximum width of about 100 

miles due south of Barrow. The plain is characterized 

by thousands of oriented and unoriented lakes and 

drained lake basins (Black and Barksdale, 1949), by 

meandering streams, by lack of marked relief, by numerous drained and undrained lagoons, by offshore bars, 

by numerous dunes and other eolian deposits (Black, 

1951), and by omnipresent ice-wedge polygons (Black, 

1952a and 1954) and other frost phenomena.

In that part of the province west of the Colville 

River, a slight angular unconformity separates the thin 

undeformed mantle of the Gubik Formation (Payne 

and others, 1951) from Cretaceous marine shale and 

some marine sandstone, siltstone, and mudstone. East 

of the Colville River early Tertiary nonmarine poorly 

consolidate conglomerate, silty sandstone, and siltstone 

of the Sagavanirktok Formation overlie the Cretaceous 

rocks and underlie the Gubik Formation or exclude it.
62 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

The Tertiary and Cretaceous rocks are exposed very 

rarely in low bluffs along the Arctic Ocean and along 

some major streams. These and older rocks to the 

south in the foothills and Brooks Range are the source 

of most of the Gubik Formation but otherwise have 

little direct bearing on the present study.

The Arctic coastal plain province is bounded on the 

north by the Arctic Ocean under which the profile 

extends with little or no break in slope. The province 

is bounded on the south by the Arctic foothills province, 

in places with distinct topographic break. To the west 

of the Colville River that boundary generally is between 

200 and 600 feet above sea level; to the east of the Colville River it reaches a maximum elevation above sea 

level of about 1,200 feet on the Okpilak River (Leffingwell, 1919, p. 53). As pointed out by Brooks (1906, 

p. 46), the southern boundary is gradational in places 

and is arbitrarily chosen; there it is a zone as much 

as 20 miles wide. The main distinctions between the 

provinces are in topography and genesis. The coastal 

plain has little relief and is underlain by flat-lying 

unconsolidated sediments of Quaternary age, whereas 

the foothills are rolling uplands or plateaus with beveled 

consolidated rocks of Cretaceous age at the surface. 

The coastal plain was built by deposition whereas the 

foothills were formed by erosion.

In summarizing the tectonic elements of Alaska, 

Payne (1953) showed the Meade and Barrow arches 

separating the Chukchi basin on the west and the Umiat 

basin on the east. Thus, Cretaceous bedrock (Webber, 

1947, p. 9-10) is nearer to the surface west of the Meade 

River than it is east of the river. Between the Meade 

and Kuk Rivers, the Avalik and Nigisaktuvik Rivers 

flow on or near bedrock, whereas east of the Meade River 

the Usuktuk and Topagoruk Rivers are separated from 

bedrock probably by a considerable thickness of Gubik 

sediments, except in their headwaters in the Arctic 

foothills.

GUBIK FORMATION

HISTORY

The early explorers in northern Alaska were far more 

interested in the geography of the area than in unconsolidated sediments or soils composing the surface of 

the coastal plain. Except for isolated comments regarding "ice," "mud," height of coastal bluffs, coal deposits, glacial erratics, and character of the low coastal 

banks, little was added to our knowledge of the geology 

of the area. The early explorations were reviewed by 

Leffingwell (1919, p. 69-92), and a summary of the 

knowledge amassed about the Gubik Formation was 

later given by Smith and Mertie (1930, p. 236-254).

Dall and Harris (1892, p. 260-268) were among the 

first to attempt geologic mapping of the surficial materials. They described the "ground ice formation" 

and the "Kowak clays" (Kobuk). In northern Alaska, these materials consist of

solid beds of ice of considerable thickness [that] perform the 

functions of rock strata and are covered by beds of blue clay 

containing numerous remains of Pleistocene mammals. * * * 

At a depth of 2 feet is a stratum of pure ice (not frozen soil), 

of unknown depth. This formation extends, with occasional 

gaps, [from a point somewhat north of Cape Beaufort] north to 

Point Barrow, and thence east to Return Reef, where the ice layer 

is about 6 feet above the level of the sea.

The ice was considered to be older than the Pleistocene 

mammoth and fossil horse found in the associated clays. 

The name of "Kowak clays" was suggested by Dall and 

Harris (1892, p. 265-266) for the clays independently 

deposited or superposed on the ground ice formation 

at the type locality on the Kowak (Kobuk) River. 

The clays were described as being associated with elephant remains at Skull Cliff and at many places between 

Barrow and the mouth of the Colville River. Although 

the clays were considered to be Pleistocene in age, 

neither they nor the fossil localities were described. 

Schrader (1904, p. 91-93) considerably reduced previous estimates of the areal extent of the ground ice 

formation and the Kowak clays and introduced the term 

"Gubik sand" of Pleistocene age.

It not only forms the surficial terrane of the coastal plain along 

the Colville, but seems to occur at some localities along the 

coast from the mouth of the Colville westward, in some instances apparently overlying the ground ice and probably the 

Kowak clay formation, while its inland margin probably overlaps the coastal edge of the Upper Cretaceous of the Nanushuk 

series. * * * The deposit consists of fine sand, with apparently 

an admixture of considerable silt. In some localities it seems 

to be more sandy toward the base, and more earthy toward the 

top. * * * It is ordinarily free from gravel, but in several 

instances subangular cherty pebbles ranging from mere sand 

grains to fragments as large as one-fourth inch in diameter 

were found. These occur very scatteringly and are sometimes 

roughened, as if wind worn. * * * The deposit as a rule is 

structureless or without stratification planes.

The deposit was called loess in the field for lack of a 

better term, but Schrader, recognizing that no one hypothesis of origin was satisfactory, considered it a product of "fluviatile delta [deposition] in conjunction with 

shallow coastal conditions and intense arctic freezing." 

Leffingwell (1919, p. 150) believed that the term 

Gubik was derived by the improper spelling of the 

Eskimo name for the Colville River Kupik. Nonetheless, the term Gubik has been accepted in the literature and in recent years has been broadened in scope 

to encompass all unconsolidated surficial materials overlying the Cretaceous or Tertiary rocks in the coastal 

plain. This usage is retained.
GUBIK FORMATION IN NORTHERN ALASKA 63

MINERALOGY

The Gubik Formation consists largely of complexly 

intercalated lenses and admixtures of silt and finegrained sand. In places, clay is especially abundant in 

the lower part of the formation, but elsewhere gravel 

is common near the base. Coarse-grained sand and 

gravel are thinly distributed throughout much of the 

vertical range of the deposits but are absent in many 

places. Near the surface, ice composes in places more 

than half the bulk,of the sediments, and organic matter 

is also abundant. Locally, the formation reaches a 

thickness of about 200 feet; in most places however, it 

is only a few tens of feet thick. The sediments are 

dominantly marine, but fluvial, lacustrine, eolian, 

glacial, and frost processes are involved in the deposition of the Gubik sediments at many localities. Wide 

variation of types is characteristic of most sections, but 

some zones of sand apparently extend horizontally 

many tens of miles with little change in texture or 

mineralogy.

The Gubik Formation is characterized by a complex 

suite of minerals (Payne and others, 1951; Morris, 

1952) derived, in large part, from the Cretaceous rocks 

underlying it and, in some part, from sources outside 

the province. No suites of minerals can now be given 

as being representative of facies or units of the Gubik. 

Generally, all minerals found in one unit also occur in 

the others. Statistical studies to determine percentages 

of minerals in the various units have yet to be made; not 

all minerals occurring in the formations have been 

identified.

Quartz is the dominant mineral, but in places chert 

is almost equally abundant. These minerals are obviously of several generations. Some of the grains 

probably date back to Paleozoic rocks in the Brooks 

Range, and have been worked and reworked several 

times by different agents of erosion and deposition; 

others are secondary in origin, such as doubly terminated euhedral crystals, and were formed in place. The 

quartz is clear and colorless or is colored yellow, pink, 

red, brown, and black. Surface stains of organic 

matter, carbonates, iron oxides, manganese, and other 

materials are common on some well-rounded grains. 

Other well-rounded grains are either smooth and 

polished, frosted or pitted, or angular and fresh. Inclusions within the quartz are abundant and of many 

kinds. Liquid and gas inclusions were seen; rutile and 

other unidentified inclusions are common. The chert 

is black, dark gray, brown, dark green, tan, buff, and 

cream. Most grains are well rounded, smooth, and 

polished; some are pitted, frosted, and stained; others 

are angular and fresh.

The other minerals also display a complete range from 

angular fresh unstained grains through well-rounded 

and polished or pitted grains to highly altered, 

weathered, or stained grains. The following minerals 

have been tentatively identified, although no intensive 

search or study has been attempted: garnet, andalusite, 

epidote, glaucophane, hornblende, zircon, chloritoid, 

biotite, muscovite, tourmaline, magnetite, ilmenite, 

andesine, orthoclase, microcline, kaolinite, illite, calcite, 

sphene, oligoclase, pyrite, rutile, pyroxene, olivine, 

hypersthene, volcanic glass (?), monazite, apatite, and 

staurolite. In many places the accessory minerals 

make up only 1 or 2 percent of the total, but locally it 

is estimated that they constitute 10 percent of the total.

Most gravel is composed of well-rounded polished 

chert, but some frosted, pitted grains are found locally. 

The darker-gray flinty varieties have typical percussion 

rings. Erratics compose a small percentage of the total 

(MacCarthy, 1958); a few of them are seemingly 

foreign to the bedrock of northern Alaska, including 

the Brooks Range. The foreign erratics include 

primarily red to gray granite and granite gneiss, dark 

hornblende diorite, and other igneous rocks. Some 

boulders measure several feet in diameter. Red, brown, 

yellow, and tan quartzite in cobbles several inches in 

diameter are as abundant as the igneous materials. 

These cobbles are generally well rounded and polished. 

Dark-gray to red fossiliferous marble resembling the 

Carboniferous marble of the Brooks Range is less common. In places, angular fragments of Cretaceous 

sandstone and coal derived locally are very abundant, 

especially near the lower part of the Gubik Formation.

Mineral determinations of the clay- and silt-size fractions of the Gubik Formation have not been attempted.

FOSSILS

Pleistocene to Recent fossils (Smith and Mertie, 1930, 

p. 251-254; Tappan, 1951; and MacNeil, 1957) (fig. 10) 

in the Gubik Formation include: marine invertebrate 

Foraminifera, ostracods, pelecypods, and gastropods; 

terrestrial vertebrate mammoth, mastodon, bison, horse, 

and musk ox; and fragments of deciduous and coniferous trees, shrubs, and vascular plants. Some localities are shown on figure 10. No systematic studies of the 

regional distribution and stratigraphic changes of the 

Gubik fossils have been attempted. Consequently, 

generalizations are limited to the environmental significance of local collections.

The marine fossils are invariably calcareous shallowwater forms, identical with or similar to those living 

in the sea today. No pelagic species are known. All 

are notably tolerant of brackish water. The vertebrate 

fossils have been found largely at or near the surface

717-108
168° 160° 156° 152° 148°

M

South 

FIGURE 10. Distribution of Quaternary fossils pertinent to this report, north and west of the Colville River, northern A
GUBIK FORMATION IN NORTHERN ALASKA 65

of the Gubik and in lacustrine or fluvial sediments. 

The musk ox is not now found in the coastal plain but 

has been reported in the area within historical times. 

The other vertebrates are Pleistocene in age but lived 

during a span of about a million years, from early 

Pleistocene to a time about 8,000 years ago (Sellards, 

1952). To the writer's knowledge all vertebrate fossils 

have been transported at least short distances and are 

hence of only general stratigraphic significance.

The logs of deciduous and coniferous trees in the 

coastal plain are invariably erratic, having been floated 

by water to their present resting places. A possible 

source of the logs is the foothills, where similar logs 

rooted in place have been found. Marine currents today however, carry driftwood from Alaska, Canada, 

and Russia along the northern Alaskan coast (Giddings, 

1952) and may well have done so during deposition of 

the Gubik. Many of these types now do not grow north 

of the Brooks Range. Most fragments of shrubs and 

vascular plants are similar to those now growing in the 

area.

SUBDIVISION OF THE GUBIK FORMATION

Subdivision of the Gubik Formation can be attempted 

at present only on the basis of its general appearance 

and of limited observations of textural and mineralogic 

changes. Faunal successions within the Gubik have 

yet to be established, although four faunules have been 

delimited by MacNeil (1957, p. 100) from collections 

at six localities in the coastal plain west of the Colville 

River (fig. 10). These are: (1) Peard Bay, in part, 

and Kukpowruk River Neptunea ventricosa soluta 

faunule, (2) Meade River Neptunea ventricosa comwwnis faunule, (3) Peard Bay, in part Neptunea ventricosa clarki faunule, and (4) Colville River Neptunea leffingwelli faunule. These f aunules in the Gubik 

may or may not be given in ascending order. Considering the limited time span, indicated by geomorphic evidence, represented by the deposits and the similarity of 

species, much additional collecting and field study will 

be required before any succession can be utilized for subdivision of the formation. Although it is somewhat 

premature to establish members for the formation, an 

attempt is nevertheless made to distinguish the following facies or units (fig. 9):

Barrow unit poorly sorted to well-sorted mixtures of 

clay, silt, sand, and gravel; unit grades from yellow, 

tan, and brown to black; in part, contemporaneous 

with and grades laterally into the Meade River sand 

and, in part, younger; rarely deposited directly on 

the Upper Cretaceous rocks; mostly marine; locally, 

in upper part, fluvial deposits and lacustrine deposits 

are characteristic.

Meade River unit white, yellow, buff, or light-tan 

sand; generally clean and well sorted; marine; conformable to disconformable on the Skull Cliff unit, 

but in places deposited directly on the Cretaceous 

rocks. Locally, whipped into surface dunes; in the 

south and southeast commonly loesslike. 

Skull Cliff unit sticky or greasy, generally poorly 

sorted, blue-black to dark-gray, marine clay-silt-sandcobble unit; possibly glacially derived, in part, and 

deposited unconformably on the Upper Cretaceous 

rocks in much of the coastal plain west of the Colville 

River.

Correlation of MacNeil's f aunules with these lithologic units is difficult. Faunule 1 is considered to be 

representative of part of the Barrow unit; faunule 2 

is representative of the Meade River unit; faunule 3 is 

representative of the Barrow unit or possibly the Meade 

River unit; and faunule 4 is representative of the Skull 

Cliff unit.

The three units may be further subdivided locally, 

but areal correlation cannot be contemplated with 

present knowledge. By distinguishing these three units 

it is not inferred that each represents a distinct time 

unit in itself. To the contrary, as indicated in the description of the Barrow unit, an overlap of time is likely 

between it, and the Meade River unit. The slightly 

deeper and f arther-f rom-shore sediments of the Barrow 

unit were probably deposited, at least in part when 

shallow near-shore seas were winnowing the Meade 

River sands; in places, these units interfinger. They 

grade laterally into each other and in places vertically. 

Near the contact shown on figure 9, they are only distinguished arbitrarily. The Skull Cliff unit however, is 

invariably covered with either the Meade River unit 

or the Barrow unit, except at Drew Point.

No attempt has been made to trace known horizons 

in the Gubik for more than a few miles. Consequently, 

the correlation of sections that are similar texturally or 

mineralogically may or may not be equivalent in time 

of deposition. Without question, transgressing and regressing seas reworked the older materials and had ample opportunity to deposit sediments of similar size, 

sorting, and composition at different times and different 

places or at different places at the same time; furthermore, unlike sediments were deposited contemporaneously as the shallow seas are doing today. The 

presence or absence of clay minerals and of gravel is 

used most widely in the author's correlation.

SKULL, CLIFF UNIT

The Skull Cliff unit of the Gubik Formation is the 

basal or oldest subdivision. It is poorly exposed in the 

coastal plain west of the Colville River. The unit con-
66 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

sists dominantly of clay and silt, ranging from dark 

gray to blue black when wet. It has a sticky to greasy 

feel and has undergone more induration (although 

slight) than the upper units. Its unconformable relation to the Upper Cretaceous rocks and conformable to 

disconformable relation to the overlying sediments are 

best seen at Skull Cliff, the type locality, and northeastward along the coast. The disconformable contact is a 

sharp lithologic break in several places, with slight erosion of the top of the unit.

Localities where the unit is known to be present are 

shown on figure 9. A sketch map of the Barrow area 

(fig. 11) shows depths to the top of the unit. The

Bay. The gravel and cobbles are dominantly chert, 

sandstone, and quartzite, but granite, marble, diorite, 

and other rock types are present. They are rounded to 

angular. The sand and silt sizes are dominantly quartz 

and chert of several generations; well-rounded to angular grains are equally abundant in places. The clay 

minerals have not been identified. A wide range of 

accessory minerals occurs in most outcrops. Marine 

microfossils and megafossils are sparse in most beds 

but are concentrated locally in coarse layers. Bedding 

is faint in most outcrops but is moderately well defined 

in many exposures at Drew Point (fig. 13) where it is 

horizontal and slightly wavy or undulating. The clay156 71°20'

'50' 40' 30' 156°20'

Naval Airbase/ 

,60

Special hole 7 

e> Special hole 2 

® Special hole 1 

® Camp hole 3

,30:

derived from 1948 seismic shot holes. 

Drillers logs, United Geophysical Co.

FIQUBH 11. Sketch map of the Barrow area, showing location of drill holes and depth, in feet from the surface, to the top

of the Skull Cliff unit of the Gubik Formation.

Skull Cliff unit presumably underlies most of the northern and western parts of the coastal plain west of the 

Colville River; although it was not seen in the southeastern part and precise locations are unknown, well 

drillers have reported a maximum thickness-there of 

20 feet under 180 feet of the Meade River unit. The 

greatest observed thicknesses are about 15 feet at Skull 

Cliff and 20 feet near Drew Point; the unit is generally 

less than 10 feet. At Skull Cliff and at Mitlitavik a .« 

few inches to 1 foot of residual weathered sand from 

Cretaceous sandstone lies directly under the unit. A 

thicker "weathered soil zone" observed along the Meade 

River by Webber (1947, p. 9-10) is arbitrarily included 

in the unit.

The composition of the unit varies widely both locally and regionally. Sand, gravel, and cobbles are FlGUEB i2._Coastai bluff 1.5 miles northeast of waiakpa, showing e

typical constituents at Waiakpa (fig. 12), Skull Cliff, fe<* of marine dark-gray clay of the Skull Cliff unit of the Gubik 

t . . r \ e / > ^ ^ Formation overlain by marine silts and sands and by fluvial-lacusMitlitavik, Christie Point, Nunavak, and Admiralty trine deposits of the Barrow unit. August 21,1950.
GUBIK FORMATION IN NORTHERN ALASKA 67

FIGUEE 13. Marine clayey silt and silty clay of the Skull Cliff unit of 

tlie Gubik Formation showing ice. 'Six-inch scale. Locality about 

1,300 feet east of Drew Point.

silts are commonly blocky; in places they are fissile. 

Sorting is poor (figs. 14 and 15).

The environment of deposition is marine in most localities visited by the writer. Silica, "rock flour" (?), 

which is abundant locally, erratic cobbles, poor sorting, 

and greasy feel all suggest some affinity to glacial till. 

The presence of feldspars, amphiboles, calcite, and other 

more easily weathered minerals, of marine fossils, and 

of erratic cobbles precludes the hypothesis that this unit 

is a weathered soil as proposed by Webber (1947, p. 9- 

10). However, the author has not observed the outcrops 

described by Webber along the Kuk and Meade Eivers, 

and it is possible there that advancing seas only slightly 

reworked a post-Cretaceous soil horizon. The presence 

of several inches of residual weathered sand unconf ormably underlying the unit at Skull Cliff and Mitlitavik 

shows that reworking was not accomplished everywhere.

LOCALITY DESCRIPTIONS

SKULL CLIFF

On September 5, 1947, a brief visit was made to the 

Skull Cliff area. At a point about 30 miles southwest 

of Barrow, 15 to 20 feet of crossbedded fine- to mediumgrained consolidated gray sandstone of Cretaceous age 

crops out at the base of the bank. Unconf ormably overlying this sandstone is 1 to 15 feet of dark-gray sticky 

silty clay containing pebbles of granite and chert as 

much as 4 inches in diameter. This area is considered 

the type locality for the Skull Cliff unit. The silty clay

 oo Depth of 7 to 9 feet, Drew Point.

Ignition loss 6.3 percent 

o o Depth of 7 to 9 feet, one-quarter

mile east of Drew Point. Ignition

loss 6.0 percent 

............ Depth of 15 feet, Drew Point.

Ignition loss 6.7 percent

 Depth of 8 feet, one-quarter mile 

east of Drew Point. Ignition loss 

6.6 percent

 Depth of 5 feet, 4 miles east of Drew 

Point. Ignition loss 6.8 percent

 Depth of 20 feet, 5 miles east of 

Drew Point. Ignition loss 8.2 percent

 Depth of 2 to 3 feet, 5 miles east of 

Drew Point. Ignition loss 7.6 percent

GRAIN SIZE. IN MILLIMETERS 

FIGUEE 14. Size-grade cumulative curves of the Skull Cliff unit of the Gubik Formation from Drew Point area.
68 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

i r\r\

90

cn

1- 

1 70

UJ

$

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,_ 40

Z

LU

0 Qri

LU 

CL

20

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 I

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. SAND

Very coarse

- ..

Coarse

 -

jj Medium

...

^

^

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SILT

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 \

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Medium

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CLAY

Coarse

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ID O ro O

CO o en ^ o t

o o

Depth of 16 feet, Kokolik River.

Ignition loss 8.2 percent

Depth of 12 feet. Admiralty Bay.

Ignition loss 3.0 percent

Three feet below top of unit,Walakpa

Depth of 10 feet, Christie Point. 

Ignition loss 1.7 percent 

Depth of 15 feet, Nunavak. Ignition 

loss 0.8 percent

GRAIN SIZE, IN MILLIMETERS

FIGURE 15. Size-grade cumulative curves of the Skull Cliff unit ot the Gubik Formation from Kokolik River, Admiralty Bay, Walakpa,

Christie Point, and Nunavak.

varies markedly in texture vertically and horizontally. 

The top of the unit is fairly level; the unit thickens and 

thins as it fills the uneven top of the sandstone. The 

clay is blocky in some places and fissile in others, and 

becomes more silty and sandy upward. It is very 

poorly sorted and in part resembles a marine-deposited 

till. Granite and gray to red marble erratics as large 

as 2 feet in diameter were seen at the base of the bank, 

where they seemingly were left behind after removal of 

the finer elastics.

DREW POINT

At Drew Point, 70 miles southeast of Barrow, and 

in the coastal bluff eastward for 5 miles from the 

point, the Arctic Ocean is rapidly eroding the perennially frozen sediments that rise as much as 23 feet above 

sea level. The lowermost sediments are marine silty 

clays and clayey silts (fig. 14), which are generally dark 

gray, blue black, greenish gray, or dark brown but which 

have yellow to tan blotches and irregular streaks and 

patches. Stratification, most ice veinlets, large fragments of organic matter, and most textural changes 

transect the contact of the colors. Ice in grains, 

granules, veins, dikes, and small irregular bodies (fig. 

16) makes up 25 to 60 percent of the sediment by weight. 

Silt- and clay-sized particles are about equally abundant; very fine sand is less than 10 percent. Organic 

matter makes up 6 to 8 percent of the total weight. In 

places the sediments are extremely gummy and tacky.

Various clay minerals, fragments of minerals of clay 

size, and quartz and chert of silt and sand sizes are most 

abundant in the marine sediments. Orthoclase, plagioclase, muscovite, biotite, chlorite, epidote, garnet, calcite, sphene, zircon, magnetite, ilmenite, tourmaline, 

glaucophane, hornblende, pyroxene, and other minerals 

are present. Most are fresh and angular; only the 

heavier accessories are well rounded.

FIGURE 16. Ice in marine clay-silts of the Skull Cliff unit of the Gubik 

Formation below and lacustrine deposits with peat above in a 23-foot 

bank about 5 miles east of Drew Point. August 7, 1950.
GUBIK FORMATION IN NORTHERN ALASKA 69

The marine sediments are cut into by thaw lakes, 

some of which extend to sea level, but most penetrate 

only a few feet. They leave characteristic deposits, 

readily distinguishable from the underlying marine 

deposits by their color, bedding, and sorting of the material. The lake sediments have much greater organic 

content and large undecayed woody fragments, comminuted tissues, and roots of water-loving plants in 

place. The reworking of the sediments only slightly 

increases the weathering of some of the feldspars and 

other minerals. Shapes commonly remain angular in 

the lighter fractions; the accessories were previously 

rounded. The composition generally remains the same, 

although, of course, locally sorting results in redistribution of certain minerals so that their percentage in 

any one spot is altered.

MITLITAVIK

At the lagoon immediately south of Mitlitavik 1 foot 

of dirty gray clayey silt in places overlies the Cretaceous sandstone. The silt contains mostly quartz and 

chert, but weathered angular orthoclase, angular garnet, 

and well-rounded rutile and zircon were seen. Most 

grains were coated with iron oxides.

Where the Cretaceous sandstone does not appear 

above sea level, at least & feet of dark-gray to blue-black 

sticky silty clay was seen. The clay unconf ormably underlies yellow sand of the Meade River unit. Most of 

the clay minerals have an index of more than 1.54 but 

were not identified. Quartz, chert, magnetite, and small 

fragments of other minerals were seen in the clay.

KOKOLIK

On August 30, 1947, a sample of dark blue-gray to 

black massive clayey silt (fig. 15) was collected from 

the eroding bank of the Kokolik River at about lat 

69°40' N. and long 161°55' W. The clayey silt was 

exposed vertically for 8 feet above river level and was 

capped by 12 feet of fluvial-lacustrine(?) mud and 

organic matter containing much ice. The clayey silt 

is faintly stratified horizontally and texturally and 

mineralogically resembles other silts of the Skull Cliff 

unit. Clay, clay-size minerals, quartz, and calcite are 

dominant. Chlorite, muscovite, zircon, sphene, magnetite-ilmenite, and other minerals are present. No fossils or pebbles were seen in the small exposure.

NTJNAVAK

On August 10, 1946, one sample was collected from 

the Skull Cliff unit, 9 feet above sea level (or depth of 

16 ft) in the coastal bluff at Nunavak, 5.5 miles southwest of Barrow. The base of the bluff was covered to 

a height of 6 feet by the beach deposits. The base of

the section exposed 6 feet of gray blocky clay and lenses 

of yellow clay, both containing admixed silt, sand, and 

well-rounded pebbles. The clay is overlain conformably by 8 to 13 feet of the Barrow unit. A cumulative 

curve is shown on figure 15. The mean size is 0.0031 

mm, and the sorting coefficient is more than 8.7. Clay 

is the most abundant material, but well-rounded pebbles 

of black chert, brown quartzite, red quartzite, and red 

granite as much as one-half inch in diameter are present. 

The clay-size particles seem to be composed largely of 

minute angular silica fragments; somekaolin-illite 

is indicated by the index of refraction. The sand-size 

particles are composed mostly of angular fragments of 

cloudy chert, but some clear angular quartz and scattered grains of garnet, andesine, and magnetite-ilmenite 

were also seen. Organic content of the sample is 0.8 

percent. Parts of the clay and some quartz and chert 

grains are iron stained. No mega- or microf ossils were 

seen. The sediment is slightly calcareous.

CHRISTIE POINT

During August 18-20, 1946, a sample of the gray 

sandy clayey silt (fig. 15) of the Skull Cliff unit was 

collected from a depth of 10 feet in the lagoonal bank 

about 2 miles northwest of Christie Point and 25 miles 

southeast of the Barrow airbase. The bank, locally 

called Katchicksuk Bluff, rises to a maximum of 20 feet 

above sea level and exposes 11 feet of the Skull Cliff unit 

capped by 9 feet of yellow- and greenish-brown sandy 

clayey silt of the Barrow unit. The contact is gradational over a range of several inches but apparently conformable. The mean particle size of the gray sandy 

clayey silt (Skull Cliff unit) is 0.008 mm; sorting coefficient is greater than 7.7. Except for distinct lenses 

of gravel, the largest particle size is 1 mm. Gravel 

lenses are composed of: well-rounded to angular pebbles, 

as much as 2 inches in diameter, consisting- of black, 

brown, and yellow chert; red, brown, white, and yellow 

quartzite; red granite; hornblende granite or diorite; 

cream and red sandstone; black slate; vuggy vein quartz 

and sandstone; coarse-grained dolomite; and other rock 

fragments. These lenses are as much as 10 inches thick. 

They also contain numerous fragments of pelecypods 

and possibly other marine organisms. Clay minerals 

or particles of clay size are common in the silt; organic 

content is 1.7 percent. The silt and sand fractions are 

composed dominantly of quartz and chert in angular 

to well-rounded grains. Most grains are coated with 

clay and carbonate, which are stained by iron oxides. 

Chlorite is present and ilmenite common. Wave action 

has concentrated gravel and coarse sand into a veneer 

over muck in a narrow beach along the bank.
70 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

MEADE RIVER UNIT

The Meade River unit, shown on figure 9, covers more 

than half the total area of the coastal plain west of the 

Colville Elver. It is the most uniform unit within the 

Gubik and is invariably light colored. Two facies are 

recognized: a clean wyell-sorted marine sand (fig. 17), 

wyhose surface has been wyhipped into dunes; and a fairly 

clean well-sorted uniform silt of mixed origin, commonly resembling loess (fig. 18). From 62 to 83 percent of the grains lies in the range of 0.01 and 0.05 mm 

in diameter. The sand occupies the central part of the 

coastal plain west of the Colville River, especially 

around the middle parts of the Meade and Ikpikpuk 

Rivers. The silty sediment predominates in the southern and southeastern part of the coastal plain and along 

the Colville River. These facies seem to grade laterally 

into each other over distances of several miles, although

FIGURE 17. Sand of Meade River unit of the Gubik Formation exposed 

in the 30-foot bank of the lake at lat 70°28' N. and long 157°55' W. 

August 25,1947.

FIGUEE 18. Sandy clay-silt of the Meade River unit of the Gubik Formation in a 50-foot bank near the headwater of the Topagoruk River, 

lat 70° N. and long 156°10' W. August 15, 1947.

their relationships are not clear. To the west and north 

the Meade River unit becomes more variable texturally, 

and grades laterally into the Barrow unit. The contact 

of the Meade River unit on the Skull Cliff unit was seen 

at Mitlitavik, Kuk and Meade Rivers, Admiralty Bay, 

and Ocean Point.

The maximum reported thickness of the Meade River 

unit, 180 feet, is near lat 70° N. and long 153°35' W.; 

the unit is generally several tens of feet to 100 feet 

thick. It pinches out to the south against the foothills, 

or it grades laterally into the surficial soil and valley 

bottom mucks of the foothills. The soils along the 

north edge of the foothills have presumably resulted 

largely from frost action and eolian processes; they 

have \vorked downslope by masswy asting and are several tens of feet thick in the valleys but are generally 

only a fewy inches thick on the uplands. Locally, at 

the boundary between the coastal plain and the foothills, they may be several tens of feet thick. Probably 

they are related in mode of origin at least in part to the 

loesslike materials in the Meade River unit to the north.

Except for zones that grade north and wrest into the 

Barrow unit and the local coarse sands and basal conglomerates in the lowy er part, most sediments of the 

Meade River unit are very wy ell sorted (figs. 19-23) ; 

sorting coefficients generally range from 1.2 to 1.6. 

Median size of the grains ranges from medium sand 

to silt, but such changes generally take place over distances of many miles. Recent rewrorking of the upper 

part by streams, thaw lakes, and eolian activity may 

change the textural classifications of local samples. 

Stratification is not wyell defined except in the northern 

parts of the unit, where horizontal, wy avy, or undulating 

beds are common. In other places cross-stratification is 

characteristic. In places in the silts varvelike beds may 

be seen in deposits interpreted as lacustrine. Massive, 

structureless sections seem to be common in the sand 

of the central part of the coastal plain, but slumping 

obscures most details.

The unit is dominantly quartz and chert. It is obvious that many generations of these minerals are represented, as indicated by the range from well-rounded, 

pitted, frosted, polished, or stained grains to clear 

euhedral crystals and unmodified angular fragments. 

Accessory minerals are absent locally, but a wide range 

of types is generally present. Only rarely are marine 

fossils found, and these are more common in the northern, more variable parts of the unit. Lacustrine fossils 

are particularly abundant in the upper part that had 

been rewyorked by former lakes. Bits of well-preserved 

shrubs are common throughout the section, but total 

organic content is IOWT . Dark tones characteristic of 

abundant organic matter in the other units are conspicuously absent.
GUBIK FORMATION IN NORTHERN ALASKA 71

 Depth of S.inches. Ignition loss 

25.0 percent

 Depth of 3 feet. Ignition loss 7.7 

percent

 Depth of 10 to 20 inches

 - Depth of 10 feet

D q oo° o ' o o 6 d o °- y u ^-"~i 

o o o o 

GRAIN SIZE, IN MILLIMETERS

FIGURE 19. Size-grade cumulative curves of the Meade River unit of the Gubik Formation from Sentinel Hill.

GRAVEL

100

90

80

>- 60 

DO

LU 50

LL

UJ

DC 30

UJ 

0.

20

10

SAND SILT CLAY

0 

S« 1 I O i^D O

Depth of 3 feet. Ignition loss 46.0

percent

Depth of 10 feet. Ignition loss 7.8

percent

Depth of 15 feet. Ignition loss 9.8

percent

Depth of 25 feet. Ignition loss 8.3

percent

GRAIN SIZE, IN MILLIMETERS 

FIGOBE 20. Size-grade cumulative curves of the Meade River unit of the Gubik Formation from the Topagoruk River.

717-108 O-64 3
PERCENT FINES, BY WEIGHT

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GUBIK FORMATION IN NORTHERN ALASKA 73

 Depth of 6 feet, Admiralty Bay. 

Ignition loss 2.4 percent

 Depth of 11 feet, Admiralty Bay. 

Ignition loss 0.4 percent

 Depth of 8 feet, one-eighth mile west 

of above samples at Admiralty Bay. 

Ignition loss 3.3 percent

- Depth of 1 foot, Atigaru Point. 

Ignition loss 4.1 percent

- Depth of 11 feet, Atigaru Point. 

Ignition loss 5.4 percent

GRAIN SIZE, IN MILLIMETERS 

FIQUBB 23. Size-grade cumulative curves of the Meade River unit of the Gubik Formation from Admiralty B'ay and Atigaru Point.

LOCALITY DESCRIPTIONS

SENTINEL HILL

From Sentinel Hill on the Colville Eiver, 45 miles 

below Umiat, westward to the Meade Eiver and the 

headwaters of the Kuk River, loess or loesslike material 

is as much as several tens of feet thick along the boundary between the coastal plain and the Arctic foothills. 

It is not present everywhere and overlies and apparently grades laterally into the sandy f acies of the Meade 

River unit, but the relationship is not clear. More than 

50 percent of the component particles of the silt are 

commonly between 0.01 and 0.05 mm in diameter. The 

silt is tan, buff, cream, or light yellow brown, calcareous, 

and is generally massive and structureless. On slopes 

where solifluction is effective, and in some other places, 

pseudobedding or true bedding may be found. In 

places, well-rounded polished or frosted chert pebbles 

as much as one-fourth inch in diameter are scattered 

through the deposit. In many places streams have cut 

deep valleys into the deposits, which are thicker in the 

valleys than on hills.

Seven samples were collected August 10, 1947, from 

the top of the bluff 7 miles south of Sentinel Hill. Four 

of the samples were analyzed mechanically (fig. 19). 

They have median sizes of 0.031 to 0.05 mm and sortingcoefficients of 1.4 to 2.1, although the sample having 

the sorting coefficient of 2.1 was obviously derived from 

a solifluction lobe in which material was moved a considerable distance and mixed with sand from below. 

Although much organic matter is contained in the 

samples from the active layer (the first and third 

curves on fig. 19), the samples are calcareous and 

most grains are fresh. Mineral fragments are well 

rounded to angular and obviously of several generations. Quartz and chert are dominant; tourmaline, 

sphene, zircon, amphibole, pyroxene, calcite, epidote, 

olivine, rutile, garnet, and hypersthene were identified 

tentatively, and other minerals are present.

TOPAQOBTJK

Paige, Foran, and Gilluly (1925, p. 20-21) mentioned 

that Pleistocene marine deposits of quartz sand, mud, 

and layers of coaly debris containing thin layers of 

marine shells rest unconformably upon the eroded surface of Mesozoic sandstone and shale and extend inland 

for 20 miles or more, except in a few places where low 

hills rise above the general level of the plain. Inland, 

the marine sand merges with Pleistocene fresh-water 

sand and gravel. Gilluly collected a fresh-water Pleistocene fauna from those deposits at a point about 60 

miles inland on the Topagoruk River.

On August 15,1947, a section of the loesslike material 

exposed in the headwaters of the Topagoruk River, 

about lat 70° N. and long 156° 10' W., was examined 

briefly. Banks rising about 80 feet above the stream 

were so obscured by slump that detailed sections could
74 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

not be measured. At one place it seemed that the 

lowermost 20 feet of the section was composed of silt 

with clay, fine to very fine sand, and pebbles of chert 

and gray sandstone; the upper 60 feet was dominantly 

silt, of which the uppermost 10 feet was exposed. The 

transition from the lower sandy zone to the upper silt 

took place vertically within a range of about 3 feet. 

Locally, faint horizontal beds and crossbeds containing 

pebbles and organic matter were observed in the lower 

zone; the upper zone showed faint crossbeds in which 

there was virtually no change in material. Woody 

fibers were seen throughout the section. One sample 

at a depth of 3 feet and another at a depth of 10 feet 

were analyzed mechanically (fig. 20). The median 

grain size is 0.028 and 0.027 mm; the sorting coefficient 

is 1.6; and 62 percent of the grains in one sample and 

73 percent of the grains in the other are between 0.01 

and 0.05 mm in diameter. Grains are well rounded to 

angular, frosted, and fresh. Quartz (including clear 

doubly terminated, euhedral crystals), chert, tourmaline, apatite, green garnet, muscovite, sphene, zircon, 

magnetite, amphibole, and pyroxene were tentatively 

identified; other minerals are present.

A few hundred feet from the aforementioned site and 

under a drained lake, about 50 feet of silt is exposed 

(fig. 18). The silt is distinctly stratified horizontally; 

down warped strata at the surface of the streambank is 

attributed to slump and creep. Bedding planes are set 

apart by layers of clay-rich or organic-rich laminae 

alternating with very fine to fine sand and silt. In 

places it is almost varvelike. Crossbedding is a very 

minor feature. No pebbles were seen, but thin-shelled 

lacustrine (?) gastropods were scattered throughout the 

upper 15 feet, where bedding is better defined. Figure 

20 shows a cumulative curve of a sample from a depth 

of 25 feet in the section shown on figure 18. The 

median size is 0.027 mm, the sorting coefficient is 1.2, and 

83 percent of the material is between 0.01 and 0.05 mm 

in diameter. Another sample (fig. 20) from a depth of 

15 feet has a median size of 0.028 mm, a sorting coefficient of 1.6, and 68 percent of the material is between 

0.01 and 0.05 mm in diameter. Two other samples, at 

depths of 25 and 35 feet, are similar. All the samples 

are calcareous and woody fibers are common. The 

grains, some of which are frosted, consist of many types 

and are well rounded to angular and fresh.

CENTRAL COASTAL PLAIN

North of the narrow belt of loess or loesslike deposits 

and west of the Colville Eiver is an area of dunes belonging to the Meade Eiver unit. Bounded grains of 

quartz and chert, which are yellow, tan, bluff, or light 

brown, compose the bulk of the material. Magnetite,

ilmenite, volcanic glass (?), rutile, zircon, orthoclase, 

plagioclase, and other minerals are present in small 

amounts. The composition varies from place to place, 

but few data are available. One sample collected August 15, 1947, from a dune at lat 70° 14' N. and long 

156°25' W., is typically composed of fine sand (fig. 21). 

The sorting coefficient is 1.3. Such dune areas are distinguished more by the distinctive cover of lichens, like 

Alectoria, and dark vascular plants, like Cassiope 

tetragona, than by a change in lithology of sediments. 

Similar sands were collected August 25, 1947, from 

the lake bank (fig. 17) at lat 70°28' N. and long 

157°55' W. (Black and Barksdale, 1949, pi. 5D). 

The mechanical analyses of samples from depths of 

1, 4, and 12 feet are shown on figure 21. Median grain 

size is 0.16, 0.19, and 0.16 mm; sorting coefficients are 

1.3. These samples were lost prior to microscopic examination but megascopically resembled other samples 

from the Meade Eiver unit. In the field only the upper 

2 feet of the deposit displayed typical dune structures 

and appeared to be wind deposited. The deposit overlies 1 foot of turf and organic-rich sand, which in turn 

overlies white, buff, and light-yellow fine sand extending from depths of 9 feet to lake level. The lower sand 

is clean and generally contains rounded grains. The 

unit is horizontally bedded, as if water laid. Bits of 

organic matter are scattered throughout.

MITUTAVIK

Aqueous or eolian sands similar to those in the central 

coastal plain extend westward but are mixed with other 

sediments in more complex sections. At the south end 

of the lake 8 miles south of Mitlitavik, a 10-foot section 

of fine yellow sand (fig. 22) is composed almost entirely 

of quartz and chert. In the lagoon south of Mitlitavik 

similar sands are interbedded with other sediments over 

the Cretaceous rocks. At the surface of the lagoonal 

bank clayey, silty sand (fig. 22) containing much organic matter makes up the active layer, 20 to 30 inches 

thick. Only quartz, chert, and clay are present. Immediately below is fine clean yellow to tan sand (fig. 

22), which is texturally identical with the sand to the 

east. Stratification is horizontal although poorly defined. Most of the section is partly obscured by slump, 

and details cannot be given. The slumped material 

indicates that similar sand extends to the lowermost 

part of the section. At a depth of about 50 feet, or 

about 10 feet above sea level, similar fine sand containing pebbles of fine to medium gravel was collected 

(fig. 22; the sample was weighted in favor of pebbles). 

The sand is largely quartz and chert; magnetite, ilmenite, olivine, rutile, orthoclase, calcite, sphene, plagioclase, hornblende, zircon, monazite, garnet, and other
GUBIK FORMATION IN NORTHERN ALASKA 75

minerals are also present. The pebbles are dominantly 

chert or siliceous rocks. All pebbles are well rounded 

and polished. The flinty gray pebbles are characterized by percussion rings. The sand grains are mostly 

subrounded, but range from well rounded to angular. 

Another sample was collected at a depth of about 52 

feet, 2 feet above consolidated Cretaceous sandstone and 

8 feet above sea level. It is identical to the first sample 

mentioned.

ATIQABU POINT

A brief visit on August 29, 1947, to Atigaru Point, 

Harrison Bay, revealed a 12-foot section of fine to very 

fine yellow to tan sand containing scattered pebbles of 

chert as much as one-fourth inch in diameter and numerous Foraminifera and fragments of pelecypods and 

gastropods. Macoma balthica (Linne) and M. incongrua Martens were identified by F. Stearns MacNeil 

(written communication, January 4,1957). Stratification is horizontal and slightly undulating, as shown by 

thin laminae of gray to brown silt and clay. These 

laminae are more abundant in the lower part of the 

section and tend to impart a brown color to the sand. 

In places at the base of the section the yellow sand 

grades into a dark-gray silty sand, which occurs apparently along the gradational and interfingering contact of the contemporaneous parts of the Meade River 

and Barrow units of the Gubik.

At a depth of 6 to 10 inches in the active layer on top 

of the bank, only quartz, chert, and clay minerals were 

seen; carbonates and other more easily soluble minerals 

had been destroyed, and eolian (?) silt had been added to 

the soil profile. The material is less well sorted than 

that underlying it in the permafrost. At a depth of 12 

inches in the active layer near the edge of the bank, wellrounded to angular grains of quartz and chert and 

rounded grains of rutile, monazite, titanite, zircon, 

magnetite, apatite, chloritoid, staurolite, and other accessory minerals were seen. The sand is well sorted 

(fig. 23). At a depth of 7 feet in similar sand, Cribroelphidium a/rcticum Tappan, Elphidiella sibirica 

(Goes), and other Foraminif era are common; fragments of other marine shells also occur. Identical sand 

was found at a depth of 11 feet (fig. 23). Pebbles 

eroded from the bank and concentrated on the beach 

were mostly siltstone, sandstone, and quartzite; granitic, 

diabasic, and chert pebbles are also present.

IKPIKPUK

on September 4, 1947, from the 30-foot bank of a lake. 

The sands display faint horizontal stratification. 

Caving banks obscure the details of the section. One 

of the two samples, taken from a depth of 4 feet in the 

lake bank, and a third taken from 2 feet beneath a lake 

bed 2 miles distant are virtually identical. Both are 

very fine to fine-grained sand (fig. 21), white, light 

yellow to buff, clean, and highly calcareous. Grains of 

quartz and chert of several generations compose the 

bulk of the material; they are well rounded for the most 

part, but angular grains are present. Well-rounded to 

angular calcite composes 2 to 4 percent (estimated), and 

magnetite, zircon, rutile, epidote, plagioclase, orthoclase, and several other varieties of minerals are present. 

The feldspars are subangular and cloudy but the other 

minerals are generally well rounded.

Smith and Mertie (1930, p. 254) reported finding a 

"spruce log, with roots attached" on the bar of the 

Ikpikpuk River about lat 70° N., more than 200 feet 

above sea level. Other logs were found at intervals to 

the mouth of the Ikpikpuk. They were "sound and 

unmineralized. * * * shells that seemed to be of marine 

character and were probably also washed out of the 

coastal-plain deposits were noted on the bars of the 

Ikpikpuk * * *" at about lat 70° N.

Section in unoonsolidated materials in the Ikpikpuk River valley 

about 2 miles south of the Valley of Willows

[Measured by E. J. Webber, Aug. 22, 1947]

Feet

Near the head of the Ikpikpuk River, at lat 69° 52' N. 

and long 153°50' W., two samples of clean white, yellow, 

and buff sand of the Meade Eiver unit were collected

Soil, dark-brown to black peaty; angular to subangular 

sand grains. The lower several inches becomes light 

gray to dirty cream and may contain lime 0. 75

Sand, silty, brown, yellowish-red, weathering reddish 

brown, evenly bedded. Thin shaly exposed surface 

noticeably crusted and hardened. Lenses of peaty 

sand a few inches in extent. The yellowish-red color at 

the surface becomes dark orange brown 1 to 1.5 ft from 

the surface. The grains are subangular to subrounded- 1. 5

Sand, very fine grained, and gravel lenses. Unit is well 

sorted, clean, multimineral in composition. Green 

chert, ironstone, and quartz pebbles are rounded; most 

grains are subangular. Bedding even for most part, 

but some 3- to 6-ft beds are crossbedded and contain 

coarser material, especially smooth oval granules of 

ironstone and black chert. The lower 4 to 5 ft contain 

reworked coal grains and granules in paper-thin lenses 

and crossbeds. Plant and wood remains are found 

locally _______________________________ 12.0

Sand and gravel mixture, poorly sorted, clean, crossbedded. Foreset beds dip as much as 24° SW. Broken 

coal grains and granules are abundant. Layers and 

lenses of peat and plant remains are several inches 

thick _______________________________ 5

Sand, very fine- to medium-grained ; scattered pebbles and 

granules ____________________________ 1.0

Total_____________________________ 15. 75
76 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

Section along the Ikpikpuk River at a point about 10 miles 

north from the Valley of Willows

[Measured by E. J. Webber, Aug. 24, 1947]

Feet

Soil _____________________________________ 1.0 

Sand, very fine, buff; crossbedded foreset beds dip 10°

to 15° S______________________________ 3. 5 

Silt, green, even-bedded in thin laminae____ ___ . 3 

Peaty mud, evenly bedded; a very strong organic odor;

sticks of wood_ ____ 4. 5 

Base of exposure is obscured by sand but presumably

consists of blue plastic clay.

On August 25, 1947, about 16 air miles north of the 

Valley of Willows, Webber found a spruce tree log 

about 5 to 6 inches in diameter and 4 feet long in the 

river alluvium. On August 30, 1947, he observed a 6- 

inch cottonwood log in the flood plain of the Ikpikpuk 

River, about 20 miles north of the Valley of Willows.

ADMIRALTY BAY

At the south end of Admiralty Bay as much as 15 

feet of fine-grained yellow sand unconformably overlies 

at least 2 feet of the Skull Cliff unit. Because much 

of the bank was slumped during a brief visit on August 28, 1947, details of the section are lacking. The 

mechanical analyses shown on figure 23 are typical of 

the very fine to fine-grained yellow sand. Quartz makes 

up about 75 percent, chert about 20 percent, plagioclase 

about 4 percent, and accessories about 1 percent of the 

material. Little weathering has occurred; some grains 

are stained and well rounded, and others are angular 

and clear. Calcium carbonate cement is more abundant 

at a depth of 8 feet than at 11 feet. The sands grade 

laterally within a few hundred feet to sandy silts (fig. 

23), in which sorting is poorer but in which mineral 

assemblages are similar. Stratification throughout the 

exposure is slightly undulating but generally almost 

horizontal. Cross-stratification is not common.

Sanford and Pierce (1946, p. 10) mentioned that 

fragments of shallow-water marine shells occur in sands 

overlying the Cretaceous rocks at the Meade River 

coal mine.

OCEAN POINT

On July 12, 1947, E. J. Webber (1947) studied the 

Gubik sand in the vicinity of Ocean Point on the lower 

Colville River. He noted that the Upper Cretaceous 

rocks are overlain by 1 to 2 feet of blue clay (probably 

Skull Cliff unit) and that the contact is gradational. 

The clay is overlain, generally with distinct break, by 

unconsolidated sand and some gravel. In places the 

sand contains clay lumps a few inches above the contact. 

The clay in places in the uppermost part contains some 

sand. The pebbles and cobbles in the gravel consist of 

sandstone, coal, chert, and tuff. Some turritellid

gastropods as well as thin- and thick-shelled pelecypods 

were seen in the sand and gravel immediately above the 

contact with the clay. The sand is even to crossbedded, 

with foreset beds dipping as much as 15°. Windfaceted chert pebbles are rare. Bits of wood in excellent condition, one-half inch in diameter and 6 to 7 

inches long, were seen locally. Several peat lenses or 

lumps roughly oval in shape and about 6 to 8 inches in 

diameter were also seen. One dark weathered zone about 

6 inches thick was noticed about 20 feet above the base 

of the formation. The total thickness is probably 

about 150 feet. The entire sand section is buff colored, 

grading upward from gravel at the base to silt at the 

top. Webber considered the deposits to be marine.

MEADE RIVER

Webber (1947, p. 10) stated:

About 8 miles north of the approximate boundary between 

the Arctic Plateaus and the Arctic coastal plain a thickness 

of 55 feet of unconsolidated sediments was measured in a cut 

bank along the Meade River. The contact with underlying 

bedrock was not seen. The difference in elevation of the top 

of the cutbank and the top of the adjacent hill suggests that 

an additional 30 feet of these beds overlies the cutbank section. 

East of the Meade River these deposits probably thicken, as 

described [above] * * *. The thickness of the unconsolidated 

deposits has been modified by erosion at many places near 

the southern margin of the coastal plain. Unconsolidated sand 

is their principal constituent. Locally, clay, silt, coaly debris, 

quartz, and chert pebbles, and exotic boulders of different 

igneous and metamorphic rocks are admixed with the sand. 

Beds of peat as much as 6 feet thick overlie the sands at many 

localities. Shells similar to those of species now living in the 

Arctic Ocean are found at many places in these deposits. 

Presumably the sediments are mostly marine.

The relationship of these sediments to the loesslike deposits to the east is not known.

KIKIAKRORAK

Stefansson, Thurrell, and Zumberge (1948, p. 4) 

stated:

Where seen in small exposures the Gubik sand appears to lie 

conformably on [Upper Cretaceous] rocks. Along the Colville 

River, however, in the long bluffs it is quite evident that the 

contact is not conformable. The contact between [Upper Cretaceous] rocks and the Gubik sand is a very low angle angular 

unconformity, probably not exceeding 1 to 2 degrees. In the cutbanks of the Kogohokruk [Kogosukruk] and the Kikiakrorak 

Rivers are found numerous evidences of stream-channelling of 

[Upper Cretaceous] rocks, with Gubik sand deposited in the 

channels. In one cutbank along the Colville River the Gubik 

sand was seen overlying [Upper Cretaceous] rocks in which a 

minor fault occurred. The relations were such as to leave no 

doubt that the faulting was prior to the deposition of the 

sand.

They also stated that exposures along the Kikiakrorak 

and Kogosukruk Rivers ranged in thickness from 10 to
GUBIK FORMATION IN NORTHERN ALASKA 77

150 feet but that most were only 20 to 30 feet thick. 

These sands are included in the Meade Eiver unit.

At lat 69°49' N. and long 151°53' W., along the 

Kikiakrorak Eiver, Stefansson, Thurrell, and Zumberge (1948, p. 7a, station 3) described a 75-foot section 

of the Gubik sand:

Yellow, loosely consolidated, extremely crossbedded, with crossbedding at angles up to 30°. Interbeds of peat up to 4 feet 

thick. Basal 6 inches is conglomeratic, consisting of angular 

fragments and well-rounded rocks. The angular rocks in slabs 

up to 1 foot in diameter. The rock fragments are sandstones, 

volcanic ash. minor amounts of shale.

Along the same river at lat 69°58' N. and long 151°42' 

W., Stefansson, Thurrell, and Zumberge (1948, p. 19a, 

station 82) described a 25-foot section: "Yellow-buff 

sand, unconsolidated, with layers of gray sand. Conglomeratic sporadically for 10 feet from base. Peat 

interbeds." Stefansson collected no samples of the 

Gubik.

BARROW UNIT

The Barrow unit comprises the surface sediments to 

the north and to the southwest of the Meade Eiver unit 

(fig. 9) with which it locally interfingers. Because of 

the wide area of outcrop near Barrow, it was studied 

more than the other units. The unit is characterized 

by great variability of sizes of materials, by abundant 

organic matter and ice, and by the variety of agents 

responsible for its transportation and deposition. The 

complexity of the unit has prohibited subdivision on 

an areal or stratigraphic basis. In many places 

beaches, bars, distributary deposits, and deltaic deposits 

are interspersed with shallow-water marine, lagoonal, 

lacustrine, and fluvial deposits. The uppermost materials seemingly have been reworked by several different agents. Subaerial reworking of any part of the 

marine section locally has occurred. Moreover, coastal 

bluffs are generally so low or slumped that good exposures are scarce. One of the best exposed and most 

uniform sections is along the coast southwest of Barrow. Even there complete sections are exposed for 

only a few days after major storms.

Ice in the upper part of the unit commonly occurs as 

wedges, whose growth has disturbed bedding planes 

in places to depths of 30 feet. Eeworking by thaw 

lakes especially modifies initial structures and textural 

classifications.

Lenses range from a few inches to several feet in 

thickness and from a few tens of feet to many miles in 

areal extent. Their textures vary greatly, from claysize particles to gravel; sorting is very good to very 

poor. Mineral assemblages also vary greatly, especially between lenses of different textures. Almost all 

minerals reported in the Gubik may be found in the

Barrow unit. The percentage composition of the minerals varies widely from place to place. Erratic boulders are common at the surface near the coast (MacCarthy, 1958) and are scarce inland.

The relation of the Barrow unit to the Meade Eiver 

unit is not entirely clear. Lateral gradation of the 

two units seems to be established, at least in part, for 

the Barrow unit lies conformably on the Skull Cliff 

unit at Christie Point, and locally the Meade Eiver 

unit also lies conformably on the Skull Cliff unit. Locally, both units lie unconformably on the Skull Cliff 

unit. Whether the southwestern part of the Barrow 

unit is contemporaneous with the northern part is not 

known; greater erosion of the southwestern part suggests that it may be older.

LOCALITY DESCRIPTIONS

SKULL CLIFF

Leffingwell (1919, p. 149-150) briefly mentioned that 

horizontal greenish-yellow sands overlying blue-black 

"mud shales" crop out in a continuous bank as much 

as 50 feet high from Barrow to Peard Bay. No fossils 

were found in the shales, but locally the sands contain 

numerous shells, mostly of a single species. The sands 

are correlated here with the Barrow unit, and the lower 

blue-black shales with the Skull Cliff unit. Meek 

(1923, p. 412-414) described in more detail the Pleistocene sediments overlying Cretaceous rocks at Skull 

Cliff where Leffingwell collected fossils. The Pleistocene sediments are about 45 feet thick. The lower beds 

consist of alternate layers of friable, unconsolidated 

yellow sands and black fissile "mud shales"; the upper 

part consists of massive beds of poorly stratified yellow 

sand with practically no "shale." Chert pebbles are 

scattered throughout the upper sands. Few of the 

lower beds exceed 3 or 4 inches in thickness, but one 

"shaly" layer about 8 inches thick was noted. Meek 

recognized that the contact of the unconsolidated upper 

sediments with the Lower Cretaceous sandstone was 

slightly irregular and represented "some lapse in time."

To the southwest of Skull Cliff and extending into 

Peard Bay, Meek (1923, p. 412) differentiated black 

"mud shales" that grade into almost pure sands toward 

the top and that overlie,the "formations" at Skull Cliff. 

Scattered thin lenses of "conglomerate" appear in the 

section, the pebbles consisting for the most part of dense 

black chert. The surface covering is a sandy loam, 

about 10 feet thick, admixed with considerable vegetable material. All beds in the outcrop, according to 

Meek, were affected by slight upwarping. Dips do not 

exceed 2° or 3°. Only the upper 25 feet of the Pleistocene section at Skull Cliff is fossiliferous, although presumably the entire unconsolidated section, according to 

Meek, represents only one period of deposition.
78 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

On September 5, 1947, the writer visited the Skull 

Cliff area. At a point about 30 miles southwest of Barrow, 15 to 20 feet of crossbedded fine- to mediumgrained consolidated gray sandstone of Cretaceous age 

crops out at the base of the bank. Overlying the sandstone unconformably is 1 foot to 15 feet of the dark 

clayey Skull Cliff unit. Overlying the silty clay in 

places apparently conformably and in others disconformably is 4 to 15 feet of tan, brown, and yellow very 

fine to fine-grained marine sand. Clean frosted grains 

are common in places and appear eolian. Elsewhere 

clay and silt are abundant and contain pebbles and 

numerous marine megafossils and microfossils. In 

general, the silt content of the upper sand is greater 

toward the base but is highly variable laterally and 

vertically. This sand is considered to be part of the 

Barrow unit.

The height of the bank is irregular to the northeast 

and seems to vary directly as the silty clay zone of the 

Skull Cliff unit thickens or thins and underlying bedrock is high or low. In other places the clay is removed 

entirely or is cut into by ancient streams. Individual 

channels cut into the Skull Cliff unit are a few tens of 

feet to several hundred feet in width and are backfilled 

with sediments from the Barrow unit. Fluvial and 

deltaic deposits of muds, sand, and gravel appear. 

Lenticular crossbedded and deltaic structures are emphasized by the contrast between clean yellow-tan sand, 

black organic-rich clay-silt, and other mixtures. Fragments of willows (?) are common in some lenses. The 

deltaic deposits are in turn overlain by tan, yellow, and 

brown marine sand.

WALAKPA

The coast 1.5 to 3.0 miles northeast of Walakpa (fig. 

12) was visited August 21,1950. Unconformably overlying the Skull Cliff unit is 10 to 16 feet of marine 

silt, sand, and clay, which are locally crossbedded, 

gravelly, and highly fossiliferous. The interval is 

extremely variable vertically and horizontally: lenses 

and laminae range from pure very well sorted textural 

units to complex poorly sorted mixtures (fig. 24). 

Some of the lenses and laminae are rich in organic 

matter, and others are clean. These are part of the 

Barrow unit. Locally, fluvial deposits displace the 

marine sediments in channels a few feet thick and a few 

tens of feet wide in the upper part. The marine sediments grade into overlying beds of fluvial and lacustrine origin that are 10 to 15 feet thick (fig. 25) and 

contain broad, shallow ice wedges. Considerable organic matter is in distinctive pond deposits and lenses 

of fluvial origin, and is scattered throughout much of 

the sediment. These three distinct units of the Gubik

 Depth of 4 feet

 Depth of 4 to 5 feet

 Depth of 5 to 6 feet

 " Depth of 9 feet 

o oo Qepth of 17 feet

Depth of 18 feet

Depth of 20 feet

Depth of 21 feet

Depth of 23 feet

Depth of 23 feet

(lateral variant of above)

GRAIN SIZE, !N MILLIMETERS

FIGURE 24. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Walakpa.
GUBIK FORMATION IN NORTHERN ALASKA 79

FIGURE 25. Lacustrine deposits over fluvial (?) deposits In bank about 

3 miles northeast of Walakpa. August 21, 1950.

Formation produce slight terraces in places where the 

younger units have been eroded back from bluffs more 

than the older units (fig. 12).

About 2 to 3 miles northeast of the aforementioned 

exposures the bank is only 20 feet high, and the lake 

sediments extend to depths as great as 12 feet. Sediments in the lower 8 feet are correlated with the Skull 

Cliff unit (fig. 15). Fluvial silt, sand, and gravel 

are common in channels cut into the top of the marine 

sediments. Iron staining of sediments under the lakes 

extends to depths of 6 feet. To the northeast gravel 

becomes a prominent part of the marine deposits. Numerous irregular structures are interpreted as fossil ice 

wedges, ice-shove features, and primary deposition 

around ice blocks in former beaches or bars. The age 

of the lake is not known, but the sediment in the upper 

12 feet is considered to be part of the Barrow unit.

FIGURE 26. Part of the Barrow unit of the Gubik Formation 

at Nunavak, showing gray blocky sandy silty clay at base, 

a thin lens of clean yellow sand In the center, and yellowbrown blocky clayey silty sand at top. August 10, 1946'.

quartz. Sand and silt sizes predominate (fig. 27), and 

the mean particle size is 0.063 mm; clay and pebbles are 

present, and the sorting coefficient is 4.1. Organic content is 0.3 percent; carbonate reaction to HC1 is strong. 

Most quartz grains are iron stained and coated with 

clay and carbonates. Ilmenite is common; sphene, 

muscovite, and chlorite were seen. Fragments of 

foraminiferal( ?) tests are common.

NUNAVAK

On August 10,1946, the writer collected samples from 

the Barrow unit at Nunavak, 5.5 miles southwest of 

Barrow. The top of the bluff is 20 to 25 feet above 

sea level. The upper 8 to 13 feet of the bluff is composed of clayey silt horizontally interbedded with clean 

sand in thin laminae and lenses as much as a f ew inches 

in thickness (fig. 26). These beds of the Barrow unit 

are conformable on the Skull Cliff unit. The upper 

sands are bluff, yellow, cream, and brown; the silts are 

yellowish brown to brown. One sample from a point 

about 7 feet beneath the surface and 18 feet above sea 

level was composed dominantly of rounded to angular

CHRISTIE POINT

During August 18-20, 1946, samples of the Barrow 

unit were obtained at depths of 4 and 5 feet in the 

lagoonal bank about 2 miles northwest of Christie Point 

and 25 miles southeast of the Barrow airbase. These 

samples were taken below the peaty silt fillings in surface polygon ponds that extended as much as 4 feet 

below the surface. The bank, locally called Katchicksuk Bluff, rises a maximum of 20 feet above sea level 

and exposes an irregular thickness of yellow-brown 

sandy clayey silt (fig. 27) over greenish-brown sandy 

clayey silt (fig. 27), which in turn is underlain by 11 

feet of gray sandy clayey silt of the Skull Cliff unit.
80 EXPLORATION OF NAVAL PETROLEUM RESERVE, NO. 4. ALASKA, 1944-53

The exposed beds resemble those at Nunavak. Only 

the upper 9 feet of the section is considered to be part 

of the Barrow unit. Horizontal bedding is vaguely 

distinguishable in a few places; most beds are cut and 

highly contorted by ice wedges.

The mean particle size of the two upper beds is 0.061 

and 0.037; sorting coefficients are 2.3 and 5.8. The 

largest grain size in each is 3 and 2 mm in diameter, 

respectively. The silt and sand fractions are composed 

dominantly of angular to well-rounded grains of quartz 

and chert. Most are coated with clay and carbonate 

stained with iron. Chlorite is present. Fresh angular 

andesine was recognized in the greenish-brown zone 5 

feet below the surface. Ilmenite was common to both 

beds. Colorless transparent hexagons of kaolinite(?) 

and illite(?) are increasingly common downward. 

Scattered pebbles of chert, quartzite, and other rocks 

were seen in the upper beds. Organic content increased 

downward from 0.4 to 1.4 percent. Minute shell fragments were seen in each sample; Foraminifera of unknown species were recognized in the lower sample.

The yellow-brown and greenish-brown silts interfinger complexly; the upper yellow-brown silt is considered to be the oxidized phase of the greenish-brown 

silt. The greenish-brown silt conformably overlies the 

gray silt, and in places the contact is irregularly gradational over several inches.

BAKBOW

On September 3, 1946, and again on July 24, 1950, 

samples of the Barrow unit were collected from the ice

cellar at the naval airbase at Barrow. The cellar is in 

an area of high-centered polygons, about 750 feet from 

the ocean and directly southeast of the camp. A shaft 

was sunk in the center of a polygon about 30 feet in 

diameter. The shaft was open for inspection only 

briefly during initial construction of the cellar, which 

during 1946 extended to a depth of 22 feet from the 

surface. During 1950 the cellar was enlarged laterally 

and extended to a maximum depth of 33 feet. 

The following section was revealed:

Section ewposed in 1946 in ice cellar, naval airbase, Barrow

Thickness 

(feet)

Vegetation and sandy clayey silt, light-tan or brown on 

top to dark-brown at base the top of permafrost___ 2

Peat and silt. The peat is in a lens striking N. 75° E. and 

dipping 70° S. Shreds and stringers of peat 1 to 6 in 

thick and 1 in to 4 ft in length parallel the lens. The 

upper 1 ft of the peat contains considerable gray sandy 

silt that grades over a vertical height of 1 to 3 in into 

the dark-brown sandy clayey silt 1-4

Silt-clay, gray and sand with pebbles (fig. 28) and much 

granular ice. One ice wedge was 6 ft in height and 6 

inches in width. Noncalcareous. Organic matter is 

3.8 percent in one sample near the top (at a depth of 6 

ft) ; the bulk of the sand is well rounded to angular 

quartz and chert of several generations, coated with 

organic material; median size is 0.097 mm and the sorting coefficient is 4.0. The pebbles are dominantly wellrounded and polished chert as much as one-half inch in 

diameter. Clean tan sand in zones a few inches in 

dimension are intercalated at the base__ _ _ 5-6

100

90

I 70

>- 60 

CD

20

10

GRAVEL

>t Q>

SAND

> o

"^ ID

SILT

\

CLAY

\

Depth of 5 feet, Nunavak

 Depth of 10 feet, Nunavak

 - - Depth of 15 feet, Nunavak

-- - Depth of 4 feet, Christie Point 

........ Depth of 5 feet, Christie Point

CO 0 --1 °0 -o " 

O O O O o° O

°-

o 5 6 

o 6 §

GRAIN SIZE, IN MILLIMETERS

FIGURE 27. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Nunavak and Christie Point.
GUBIK FORMATION IN NORTHERN ALASKA 81

Section exposed in 1946 in ice cellar, naval airbase, Barrow 

Continued

Thickness 

(feet)

Sand, clean, tan; irregular bedding: layers of gravel a 

fraction of an inch to a few inches thick and zones of 

gray sand are interbedded irregularly. The gravel is 

largely iron stained; some sand is also irregularly 

stained. Bedding is virtually horizontal in the tan sand 

and very poorly denned, whereas the gravel layers and 

iron-stained zones show well-defined undulating to contorted bedding. One sample of fine to very fine clean 

tan sand collected at a depth of 9 ft is largely quartz 

and chert, but muscovite, tourmaline, vesuvianite( ?), 

apatite, microcline, andesine, ilmenite, magnetite, chlorite, sphene, hornblende, topaz, tremolite( ?), epidote, 

zircon, garnet, and other unidentified minerals were 

seen. Grains are well rounded to angular; the quartz 

and chert are of several generations or kinds. Pebbles 

consisting mostly of chert and less commonly of quartzite and granitic rock as much as one-fourth inch in diameter are scattered throughout. Foraminiferal 

shells and fragments of larger shells are scattered 

throughout. Another sample also collected at a depth 

of 9 ft but in a different part of the shaft consists of 

iron-stained sand and gravel. It is composed dominantly of quartz and chert of several generations as 

in the aforementioned sample; partly altered andesine 

and some chlorite and other minerals were seen, but the 

variety in mineral composition is not as great as in the 

previously mentioned sample. The gravel is well 

rounded; the sand is angular to well rounded. A 

similar sample of the iron-stained sand and gravel 

from a depth of 15 ft contained more fragments of 

marine megafossils. Neptunea and Macoma are 

present _ - _ 10-13

Section exposed in 1946 in ice cellar, naval airbase, Barrow 

Continued

Thickness 

(feet)

Sand, tan, to gray, generally very fine to fine-grained. 

Acute-angle crossbedding in the lower part; many thin 

layers of oil-stained sand and scattered pebbles in the 

upper 2 ft; undulating bedding in lower part contrasts 

with the generally contorted bedding in upper part. 

One sample of the tan sand at a depth of 18 ft and one 

sample of the oil-stained sand and scattered pebbles 

at the same depth are similar texturally to those above. 

One sample at 19 ft also contains glaucophane, albite, 

rutile, and other unidentified minerals in addition to 

those listed previously. Similar material extends to 

the bottom of the ice cellar at 22 ft (fig. 28). In the 

lowermost sample the median size is 0.13 mm and the 

sorting coefficient is 1.3 _ 4-6

The top of the section exposed in 1950 was at a depth 

of 23 feet, directly below the above section. It is as 

follows:

Thickness 

(feet)

Sand, horizontally bedded, gray to tan and brown,'mottled, clean, very fine to medium-grained; scattered 

pebbles and shell fragments. Organic-rich layers *4 to 

y2 inch apart and He to % inch thick are abundant 

throughout. Shells are particularly abundant in the 

lower part, which shows slight unconformity with the 

underlying gray to tan sands without organic layers 2. 5'

Sand, tan to gray, uniformly fine; little or no organic 

layers, shell fragments, or pebbles 2. 5

Sand, bedded, fine; organic-rich layers scattered irregularly throughout____ 4. 0

Sand, gray, silty, and gravel pebbles as large as 2 inches 

in diameter; numerous shells and much organic matter in thin lenses___ 1. 0

Depth of 6 feet. Ignition loss 3.8

percent

Depth of 22 feet. Ignition loss 0.0

percent

Depth of 24 to 26 feet. Ignition

loss 1.6 percent

Depth of 27 to 30 feet. Ignition

loss 1.4 percent

Depth of 31 to 33 feet. Ignition

loss 1.4 percent

GRAIN SIZE, IN MILLIMETERS 

FIGURE 28. Size-grade cumulative curves of the Barrow unit of the Gubik Formation, Barrow area, from airbase ice cellar.
82 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

Eleven samples were taken from the lower part of 

the aforementioned section. Mineralogically and texturally the samples resembled the gray to tan sand 

overlying them. One channel sample from 24 to 26 

feet is shown by the cumulative curve (fig. 28); the 

median size is 0.16 mm and the sorting coefficient is 

1.3. Another sample from 27 to 30 feet is represented 

on figure 28; the median size is 0.18 mm and the sorting 

coefficient is 1.3. One sample from 28 feet and one 

from 29.5 feet are similar; median sizes are 0.12 mm 

and 0.16 mm, and sorting coefficients are 1.3. A 

channel sample from a depth of 31 to 33 feet is represented on figure 28; its median size is 0.17 mm and sorting coefficient is 1.2.

One sample of an organic-rich lens of fine- to very 

fine grained sand, coal fragments, and chert pebbles as 

much as half an inch in diameter is very rich in foraminifer, ostracode, and mollusk fragments. Pleistocene foraminifers of the genera Cribroelphidi'wn and 

Elphidiella are present; numerous specimens of Recent 

species were seen. Coal fragments make up about 10 

percent of the total. All sand grains are coated with 

organic material.

The uppermost 9 feet of the section presumably 

represents lagoonal deposition and later lacustrine 

modification. Calcium is leached to at least 6 feet, as 

shown by tests with HC1. A zone of interfingering 

marine and lagoonal deposits extends downward a few 

feet to a depth perhaps of about 15 feet. The lower 

beds are entirely marine. The material is virtually the 

same from the base of the section to the depth to which 

lacustrine modification was effective about 6 feet or 

as much as 8 feet. Shallow-water marine crossbedding 

and contorted bedding resulting from ice shoving(?) 

are representative of about half of the section; these 

structures alternate with horizontal or slightly undulating beds. Sorting is generally very good except for 

pebble-rich layers, but pebbles are scattered throughout. Lenses of organic-rich sand, gravel beds, and 

fossil-rich zones are presumably the result of slight 

irregularities in the sea floor, but Foraminifera and 

mollusk fragments are scattered throughout. The dominant mineral is quartz. Grains range from well 

rounded, stained, and frosted to fresh and angular; 

euhedral crystals, some of which are doubly terminated, 

also occur. Typical grains are clear and colorless, pink, 

red, brown, and black. Rutile, liquid, and other inclusions are common in some grains. Obviously, many 

sources and many generations are represented. Chert 

or flint is the next most abundant mineral. It is 

typically white, cream, tan, brown, green, and black 

and is commonly translucent to opaque. Most grains 

are well rounded and polished; the darker flinty varieties commonly have percussion marks on the surface.

They are finely crystalline or fibrous. Carbon (?) is 

the most abundant inclusion in the siliceous minerals, 

but iron oxides (?), manganese (?), fresh pyrite cubes, 

and other materials are common. The other minerals 

mentioned previously are largely missing in the upper 

part that was subjected to longer weathering or are 

reduced in numbers and show considerable alteration. 

In the cleaner parts of the lower beds most grains are 

fresh; many are angular, although rounding is characteristic. Texturally these beds resemble parts of the 

Meade River unit but are referred to the Barrow unit. 

In the summer of 1950 several special holes were 

drilled near the naval airbase at Barrow (fig. 9) by 

Arctic Contractors for the Arctic Research Laboratory 

permafrost investigations. Partial cores were obtained 

from holes 1, 2, and 7 and were examined by Florence 

Rucker Collins, U.S. Geological Survey in Fairbanks. 

By the use of compressed air as the drilling fluid, cores 

were obtained in a frozen state from another special 

hole, called Camp Hole 3. The cores were shipped to 

Fairbanks and examined by Florence Rucker Collins 

while still frozen. The cores represent intervals between 

10 and 71 feet and 104 and 109 feet. She described the 

cores as follows (written communication, March 21, 

1951) :

All the cores received are of Gubik sediments, probably of 

Pleistocene age. The sands [fig. 29] are distinctive, unusually 

well rounded, and typically contain a large amount of yellow 

and orange quartz, and yellow and black chert grains. Most 

of the grain surfaces are exceptionally well polished; some are 

pitted, and a few frosted. Other sediments present often show 

very poor sorting, with grain size ranging from pebbles larger 

than 1 cm in diameter to clay. Sieve analyses of the poorly 

sorted material usually have two maximums, and in one case 

three well-defined maximums (coarse sand and pebbles, very 

fine sand, and clay, in the sample 11-16 feet, hole 2) are 

present. The cleaner sands are sparsely fossiliferous; the 

"pebbly clay" contains a moderate number of ostracods and 

Foraminifera, while the interlaminated silty sand and silt at 

34 feet in hole 2 had abundant calcareous Foraminifera and 

many ostracods. The Foraminifera are indicative of a marine 

environment; the ostracods, according to F. H. Swain, 1949, 

are types found in cold marine neritic environment of moderate 

depth, having "living relatives in the north Atlantic and Arctic 

Oceans, in water generally more than 10 fathoms and less than 

100 fathoms deep."

Recovery of cores was too poor to permit correlation 

except between two holes, Nos. 2 and 7, about 1,500 feet 

apart. (See fig. 11.) Between a depth of 10 and 50 

feet, the two holes apparently penetrated the same 

sequence of beds at about the same depths. A thin but 

distinctive pebbly clay bed occurs between 25 and 30 

feet in both holes; brown laminae in sands immediately 

above and below the clay beds are present in both. 

Medium-grained gray clay occurs in the bottom of both 

holes at a depth of about 100 feet. Detailed logs follow.
GUBIK FORMATION IN NORTHERN ALASKA 83

Depth of 11 to 16 feet 

Depth of 19 feet 

Depth of 24.5 feet 

Depth of 27 feet 

Depth of 28.5 feet 

Depth of 31 to 33 feet 

Depth of 39 feet 

Depth of 45 feet

GRAIN SIZE, IN MILLIMETERS 

FIGDBE 29. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Barrow area drill cores.

Arctic Contractors hole 2, Barrow, Alaska

[A continuous series of cores from 11 to 52 ft with a total recovery 

of 26 ft 9 in and a 3'8-in section of core from 96 to 101 ft were sent 

to the laboratory]

Depth

(feet)

11-16

Amount

recovered

Ft in

Description

Clay, silty, very sandy, grayish-yellow (silt 

and clay fraction is yellow; washed sand 

is yellowish gray). The sediment lacks 

any evidence of bedding or other structures possibly because of collapse of the 

material after melting of the permafrost. 

Scattered well-rounded gray, brown, or 

black chert grains and pebbles (1 to 5 mm 

in diameter) are scattered throughout. 

The sieve analysis (fig. 29) has 3 maximums and demonstrates poor sorting; 

carbonate content at the same depth is 

8.06 percent. The sand grains are well 

rounded to subangular and consist largely of 

clear quartz, but 10 to 15 percent consists 

of white, yellow, and orange quartz and 

orange and black chert. Scattered frosted 

grains are present, and pitted grains are 

common. A few clear quartz grains are 

angular, having sharp edges and low 

sphericity; one euhedral unworn bipyramidal quartz crystal was seen. Mica and 

pyrite are absent, but there are sparse 

grains of other minerals and rock fragments. All the grains have fresh and 

some have polished surfaces, except for 

the pitted or frosted ones mentioned 

above. Fragments of pelecypods and 

ostracodes are present; two specimens of 

a calcareous foraminifer (Eponides sp.) 

were found.

Arctic Contractors hole 2, Barrow, Alaska Continued

Depth 

(feet)

16-21

21-26

Amount

recovered

Ft in

Description

Sandy mud (drilling mud?), light-gray.

Sand, fine-grained, very silty and argillaceous, olive-gray, noncalcareous. A 

sieve analysis of a sample from 19 ft (fig. 

29) shows a bimodal distribution with 

somewhat better sorting than that in the 

sample from 11 to 16 ft. Sand grains 

from a sample at 21 ft are well rounded to 

subangular and consist predominantly of 

clear quartz, but 10 to 15 percent consists 

of white quartz, green, gray, and black 

chert, and other rock fragments; scattered 

grains of angular clear quartz are also 

present in this sample. Yellow quartz 

and chert is present but in smaller 

quantities than in the interval at 11 to 

16 ft. Scarce black chert granules (2 mm 

diameter) were also found. The olivegray color of the hand specimen is due to 

the large amount of brown silt and clay 

that is mixed with the sand. No microfossils are present.

Sand, fine-grained, very silty and argillaceous, olive-gray, noncalcareous, as in 

unit above.

Sand, fine-grained, slightly silty and argillaceous, light-yellowish-gray. The color of 

this sand and of the yellowish-gray sands 

below is both lighter and yellower than 

that in the section from 16 to 21 ft because 

the darker silt and clay material is missing 

and only sand is present.

Sand as in 8-in interval above; lower part 

contains patches of clean fine-grained 

sand and grades into unit below.
84 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

Arctic Contractors hole 2, Barrow, Alaska Continued

Depth

(feet)

26-31

.

31-35

Amount

recovered

Ft in

2 1

1

10

4

3

3

2 4

2 4

Description

Sand, as in 7-in interval above, but with

scattered irregularly shaped patches of

argillaceous olive-gray silt which show no

particular orientation. (The sieve analysis, fig. 29, includes both types of sediments.) No bedding is visible in any

part of the core. Sieve analysis (fig. 29)

is from 24 ft 6 ins. Sand grains are similar

to those described in the lower part of the

core from 16 to 21 ft. One specimen of

Nonion jarvisi Thalmann (a Cretaceous

calcareous foraminifer) and one ostracode

fragment were the only fossils found in

the sample from 24 ft 6 ins.

Sand alternating with argillaceous patches,

and sandy silt and clay containing streaks

of clean sand. A few brown carbonaceous

laminae at 26% ft.

Sand, fine-grained, light-yellowish-gray,

noncalcareous with scarce brown to black

carbonaceous laminae which are flat lying

and contain medium-sand-size coal particles as well as finer carbonaceous material.

A sieve analysis (fig. 29) for a sample

from 27 ft is given. Washed sample

from 27 ft has grains similar to those from

11 to 16 ft, but contains much more

orange quartz and less clear quartz; estimated 60 percent clear quartz, 15 percent

orange quartz, and the remainder chert

and other minerals. Ostracode fragments

are present.

Clay, silty, black, carbonaceous, calcareous;

scattered black chert pebbles as much as

4 mm in diameter. Very fine silty yellowish-gray noncalcareous sand is present

in distorted laminae and patches in upper

2 ins of interval.

Sand, fine-grained, as in unit above.

Clay, as in unit above, but with more chert

pebbles (as much as 1 cm in diameter)

and coal chips 1 cm across. Size range

of particles is shown on fig. 29. Pelecypod shell fragments, ostracodes, and some

calcareous Foraminifera were found in

this and lower samples; the ostracodes

are marine, from cold water of moderate

depth (neritic). Fossils identified by

F. H. Swain from photographs. The

following species are represented : 3 valves

of Leguminocythereis cf. L. septentrionalis

(Brady); 3 valves of Cythere sp. aff. C.

concinna Jones; 4 valves of Cytheridea sp.

aff. C. punctillata Brady. Foraminifera

collected consist of 2 Elphidiella sp., 3

Elphidium sp., 2 Cribroelphidium articum

Tappan, 1 Pyrulina sp., 1 Cassidulina sp.,

and 1 Eponides sp.

Sand, fine-grained, light-yellowish-gray; the

composition, except for the presence of

abundant grains of coal, is similar to that

at 21 ft.

Sand as in unit above; a 5-mm layer of

rounded black and yellow chert pebbles

(3 to 5 mm in diameter) and pelecypod

shell fragments at the base of the section.

A sieve analysis (fig. 29) shows fairly

good sorting. The sand is about 20

percent orange cuartz; otherwise it is

similar to that described in unit above.

Foraminifera present are 2 specimens

each of 2 species of Eponides, 1 Cassidulina teretis Tappan, and 6 specimens

representing 3 species of Nonion.

Arctic Contractors hole 2, Barrow, Alaska Continued

Depth

(feet)

-

35-41

42-52

96-101

Amount

recovered

Ft in

1 8

3 6

3 6

3 2

Description

Interlaminated oliveTgray silt, slightly calcareous, and light-olive-gray very fine

sand, both very argillaceous and at places

slightly crossbedded (dips 0° to 5°).

Scarce laminae of fine grained sand. At

the top of the section and from 34^ to 35 ft

are scattered brown carbonaceous laminae,

which coarsen and thicken with depth.

Foraminifera are abundant in the sample

from 34 ft, and Ostracoda more numerous

than in other samples.

Ostracodes: 13 valves of Cythere sp.

aff. C. concinna Jones, 10 of which are

immature; 1 valve of C. cf. C. pulchella

Brady; 3 valves of C. sp. aff. C. cicatricosa Reuss; 2 valves of Cytheridea sp. aff.

C. punctillata Brady; 1 unidentifiable

small ridged valve. Numerous ostracode

fragments unidentified.

Foraminifera : Nonion jarvisi Thalmann

is abundant, with nearly 50 specimens;

several related species total over 100

specimens. Elphidium is also abundant,

with 4 species and approximately 75

specimens. Cribroelphidium articum Tappan is common, with some 20 specimens.

Eponides is represented by some 25 specimens of 4 species and Anomalina by

about 15 specimens of a single species.

Cassidulina teretis Tappan and C. sp.

have 5 specimens each; and there are 3

specimens of Pyrulina sp. and 3 of

Pullenia sp.

Sand, fine-grained, light-yellowish-gray;

laminae "of yellowish-gray fine-grained

very silty and argillaceous sand and

scarce thin beds of olive-gray clay. The

sieve analysis shown on figure 29 is for a

sample taken at 39 ft; carbonate content

at the same depth is 3.98 percent.

Ostracodes present are 1 valve of

Haplocytheridea cf. H. sorbyana (Jones)

and 1 valve of Cythere sp. aff. C. concinna

Jones. Foraminifera are Nonion jarvisi

Thalmann, and 3 specimens representing

2 species of Elphidium.

Sandstone, very fine grained, very silty and

argillaceous, light-olive-gray, calcareous;

slightly darker and carbonaceous toward

the bottom. A cobble larger than the

diameter of the core and composed of

quartzitic sandstone, which is very

light yellowish gray and very slightly

calcareous, occurs 2 ins above the base

of the core. A sieve analysis for a

sample taken at a depth of 45 ft is given

on figure 29; carbonate content at the

same depth is 28.9 percent.

Foraminifera are as follows 1 Eponides

sp., 1 Cassidulina sp., 1 Nonion sp., and

1 valve of Haplocytheridea cf. H. sorbyana

Jones.

Clay shale, -medium -light-gray; patches of

yellow iron stain in the upper few inches

and at the base. The shale is soft and

noncalcareous, and contains abundant

coarse to very fine grained sand and silt

similar to that in the sands described in

the unit above. Fracture is irregular

to hackly, and no bedding is visible.

Foraminifera were more common in this

sample than in any other sample except

that from 34 ft; the following types are

represented: 1 Quinqueloculina; 1 large
GUBIK FORMATION IN NORTHERN ALASKA 85 

Arctic Contractors hole 2, Barrow, Alaska Continued Arctic Contractors hole 7, Barrow, Alaska Continued

Depth 

(feet)

Amount 

recovered 

Ft in

Description

Elphidium and 5 smaller ones representing 2 other species; 1 specimen each of 

two species of Pyrulina; 4 specimens of 

Nonion sp., 1 Nonion jarvisi Thalmann, 

and 1 specimen of a different species of 

Nonion; and 2 Cassidulina teretis Tappan.

Arctic Contractors hole 7, Barrow, Alaska

[Cores from 12 to 52 ft and from 104 to 109 ft -with a total recovery 

of 36 ft 6 in were sent to the laboratory. Because the sediments are 

similar to those in hole 2, neither sieve analyses nor carbonate content tests were made on these cores, and only one sample (from 12 

ft) was examined for microfossils]

Depth 

(feet)

Amount

recovered

Ft in

Description

12-22 5 6 Sand, very fine to fine-grained, very silty 

and argillaceous, grayish-yellow to olivegray; scarce pebbles (as much as 3 mm in 

diameter) of black chert scattered throughout. A geode (1 cm in diameter) of 

selenite, in a shell of loose sand grains, 

occurred 2 ft above the base of the section. 

At the base of the section, two more 

geodes were found, in a lens of clean 

orange quartz sand a few millimeters 

wider than the diameter of the core. 

Microfossils were absent from a sample 

taken from 12 ft.

Sand, fine-grained, light-yellowish-gray; 

similar to that in the 7-in. sand section 

described at 21 to 26 ft in hole 2.

Sand as in unit above but contains more 

orange grains.

Sand, silty, very fine to fine-grained, lightolive-gray; scarce brown laminae.

1 22-32 3 6 Sand, fine-grained, light-yellowish-gray, noncalcareous; scattered dark-brown carbonaceous laminae in the upper 2ft. Laminae 

are concentrated to 2}i ft from the top of 

the section but are absent below this 

depth.

1 Clay, medium-dark-gray, calcareous. 

5 Sand as in unit above but brown laminae 

are scarcer and thinner.

Clay, medium-dark-gray to dark-gray and

dark-olive-gray, calcareous. 

11 Sand as in unit above. 

4 Clay as in unit above.

10 Sand as in unit above; numerous brown 

laminae and a thin bed of sandy silt near 

the base.

Sand, as in unit above, but lacks brown 

laminae; small fragments of thin pelecypod 

shells common. 

32-37 1 6 Sand as in unit above.

1 4 Sand, very fine grained, very silty and 

argillaceous, light-olive-gray.

Sand, fine-grained, light-yellowish-gray, as 

in upper 1 ft 6 in. of core but slightly 

better sorted.

37-42 1 2 Sand, very fine grained, very silty and 

argillaceous, as in interval (1 ft 4 in.) 

above.

Clay, medium-dark-gray, very calcareous; 

abundant very well rounded black chert 

pebbles from 1 mm to 1 cm in diameter.

i Section from 26 to 30.8 ft was mixed before arrival at the Fairbanks laboratory 

(letter to T. O. Roberts from O. R. MacCarthy, Aug. 23, 1950). The core as a 

whole is very similar to that taken from 27 to 31 ft in hole 2.

Depth 

(feet)

42-47

47-52

104-109

Amount

recovered

Ft in

3 6

2

3

2 6

Description

Silt to sand, very fine grained, light-oliyegray, as in sand unit above, but with 

much larger proportion of fine material. 

No bedding visible.

Clay, slightly silty, medium-gray, noncalcareous, with scattered small (under 3 

mm) well-rounded black chert pebbles, 

and rare patches of calcareous yellow 

"clay ironstone."

Clay as in unit above, but with more silt 

and fewer pebbles, which are rare in the 

upper part and absent toward the base. 

Scattered small irregular streaks of carbonaceous black clay also present.

Clay as in unit above but lacks chert pebbles 

and is intergraded with silt at the base. 

Grades into unit below.

Sandstone that is very fine grained, very 

silty and argillaceous, light-olive-gray and 

that becomes less silty and fine grained 

with depth; similar to section from 42 to 

52 ft in hole 2. A 4-in. section from this 

interval was removed before the core arrived in Fairbanks.

Clay, medium-gray, silty, sandy (fine- to 

coarse-grained), noncalcareous. Scattered pelecypod shell fragments present. 

Similar to the core from 96 to 101 ft in 

hole 2.

Emerged bars and beaches are relatively common 

features of the Arctic coastal plain province. Some of 

these features that include lagoonal, lacustrine, and 

fluvial deposits are part of the Barrow unit. One of 

the most accessible bars is about 1 mile east of the naval 

airbase; it rises a maximum of 25 feet above sea level 

and may be traced more than 4 miles in an arcuate 

course surrounding a recently drained salt-water lake 

or lagoon. The material composing the emerged bar 

ranges from clay to gravel in lenses of various sizes and 

attitudes. These lenses range from a fraction of an 

inch to several inches in thickness and several feet to 

several tens of feet in areal extent. Sections a few feet 

apart are dissimilar. Figure 30 shows a typical section 

made on August 7, 1947, by bulldozer supervised by the 

writer. The section was cut through one of the narrowest and coarsest parts of the bar. Initial structures 

are undisturbed below the active layer, except at ice 

wedges, but were cut into on each side by waves and 

currents of lagoons or lakes that formerly occupied 

either side of the bar. Quartz and chert are the dominant minerals. Most grains are well rounded, polished, and worn, but fresh angular fragments are common. Except for local turf, the uplifted bars resemble 

the present beaches. Below the active layer, primary 

deposition structures commonly are retained unmodified.
86 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

TESHEKPUK

The north side of Teshekpuk Lake is cut 20 to 30 feet 

into yellow, tan, and brown silt and sand containing 

considerable clay locally and scattered pebbles and 

marine shell fragments. These sediments are con 

sidered to be part of the Barrow unit, although some 

beds texturally resemble the Meade River unit. On 

August 29, 1947, a brief visit was made to the head of 

the small embayment east of the prominent point on the 

north side of the lake. At one point the section is 0 to 2 

feet of peaty silt under vegetation, 10 to 15 feet of darktan to brown silty sand and sandy silt, and 8 feet of 

banded very fine grained yellow sand and silty gray 

clay. Stratification planes are undulating but continuous for at least 100 feet. One poplar (?) log 3 inches

in diameter was embedded in clayey sandy silt 1 foot 

above lake level. Fragments of plant tissue are common. Samples in a 25-foot bank were collected at 

depths of 10, 17, and 24 feet (fig. 31). Slumping and 

caving of the bank was rapid, and doubtless the position 

of each sample is only relative, as some movement of the 

face is expected. The lower sample of gray sandy 

clayey silt is dominantly quartz and chert; biotite, 

muscovite, hornblende, calcite, zircon, sphene, rutile, 

magnetite, monazite, chlorite, hypersthene, tourmaline, 

garnet, pyroxene, apatite, orthoclase, plagioclase, and 

other minerals are present. Grains are well rounded 

to angular and many are of several generations. The 

calcite is crystalline and well rounded to angular. The 

feldspars are cloudy with alteration products. The 

other samples reveal similar mineral suites.

w J^^**^' -. -V:-rt-'. u u * * w i-7--""" " ''° '.W. " W.v..- . . Q .v -Q. ^O .'1^1 O^^ U.

;^£5?^?°pv^£^

EXPLANATION

Contact or stratification plane 

Well-developed

Contact or stratification plane 

Moderately developed

FIGURE 30. Diagrammatic cross section through an uplifted bar, 1 mile east of the naval airbase near Barrow.

100

90

on

1-

ri 70

LU

> 60 

m

JS 50

uZ 

l_ 40

 z.

LU

o

LU 

CL

20

10

n

GRAVEL

Very coarse Coarse Medium 0

c 

iZ

a c

SAND

Very coarse Coarse Medium

^ s

0

c

U.

s.

\

\

V

>

II

\

s

-\

\

\

SILT

Coarse

-^

\

\

-\-

-\

\

y \

Medium

N.

\

\

S

0

c

U.

\

s

\

11

\^

*'s s

CLAY

Coarse

^-

 «^^

Medium

' -.

k

0)

ul >^

5°S

 Depth of 10 feet. Ignition loss 5.1 

percent

 Depth of 17 feet. Ignition loss 1.2

percent 

" ' Depth of 24 feet. Ignition loss 6.7

percent

\Q O fO O «" og

GRAIN SIZE, IN MILLIMETERS

FIGURE 31. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Teshekpuk Lake.
GUBIK FORMATION IN NORTHERN ALASKA 87

PEABD BAY

On August 3 to 5, 1947, six samples were obtained 

from the bluffs along the south side of Peard Bay, 

about 70 miles southwest of Barrow. The section was 

obscured by slump in most places, but locally it was 

exposed over a vertical range of 12 feet. There the 

Gubik formation consists of silt, clay, sand, and mixtures of these sediments in complexly intercalated lenses 

a fraction of an inch to several inches thick, and a few 

inches to several hundred feet in areal extent. The 

lenses range from light gray through yellow, tan, and 

brown to black; yellow-brown predominates. The 

sediments bear a strong superficial resemblance to the 

Gubik in the ice cellar at Barrow; they are referred 

to the Barrow unit.

The dominant mineral is quartz of several generations; typically it ranges from clear, colorless angular 

fragments or euhedral crystals to frosted or pitted 

stained rounded grains. Chert is the next most abundant mineral in silt and sand and in pebbles. The 

chert is generally rounded, smooth, and polished; but 

pitted, cracked, or broken fragments are common, as in 

the Barrow unit at Barrow. The chert is white, cream, 

tan, brown, green, gray, and black. These two minerals make up more than 95 percent of the material. 

Coal is a common constituent; other minerals and rocks 

are present, but microscopic studies were not completed 

prior to loss of the samples. Marine shell fragments

are scattered in most of the sections. The mechanical 

analyses shown on figure 32 are probably typical. The 

exposed materials are interpreted as shallow-water 

marine or lagoonal deposits.

CAPE SIMPSON

In 1948 at Cape Simpson, Patton (1948), investigated three oil seeps with 10 shallow tests pits and 

provided the following information on the Gubik 

Formation:

Below the frost line three types of material were encountered: 

blue-gray clay, yellow-brown silt commonly containing rounded 

chert and quartzite pebbles, and ice. The clay and silt appeared to be interbedded. Above the frost, which occurred at 

a depth of two feet, was a cover of pitch, pitch-bound silt and 

moss.

Some limey shale, limestone and ironstone float on several of 

the mounds has prompted several geologists [Paige, Foran, and 

Gilluly 1925, p. 23] to suggest that these peculiar topographic 

features are directly underlain by hardrock. However, no consolidated bedrock in place was encountered in any of the test 

pits. An occasional isolated fragment of shale or limestone 

was unearthed. It seems probable that these as well as the 

surface float were brought up from some depth by frost action.

At the northern end of the mound from which seep No. 1 [3 

miles northwest of the Cape] emerges, a 20-foot section through 

the mound is exposed in a beach bluff, The mound-forming 

material here is a blue-gray clay and massive blocks and wedges 

of ice. No consolidated bedrock was found.

Eight samples of clay and silt from the test pits were submitted to H. N. Loeblich for microfossil determinations. Of the

 ~ Depth of 2-4 feet

 " Depth of 4 feet 

Depth of 8 feet 

 Depth of 10 feet

GRAIN SIZE, IN MILLIMETERS 

FIGDEE 32. Size-grade cumulative curves of the Barrow unit of the Gubik Formation from Peard Bay.
88 EXPLORATION OF NAVAL PETROLEUM RESERVE NO. 4, ALASKA, 1944-53

eight, six were found barren. The other two contained the 

following species:

48APa 29 Brown silt, pit No. 6, seep No. 2 [2 miles southwest 

of the Cape] Elphidium spp., Cornuspira, sp., Eponides sp. 

Anomalina sp., and Nonion sp.

48APa 31 Clay, pit No. 3, seep No. 1 [3 miles northwest of 

the Cape] Elphidium A. Elphidium F, Cornuspira A, Anomalma 

D, and Quinqueloculina B.

Mrs. Leoblich states that these forms are late TertiaryQuaternary undifferentiated.

Below the surflcial cover of pitch, fresh green oil was found 

to be oozing up through steeply dipping fissures in the frozen 

ground. These fissures vary in width from several inches to 

a foot and are filled with loosely compacted, oil-saturated silt 

or clay. Both downdip and along the strike the fissures are 

highly irregular and do not appear oriented in any particular 

direction. There is evidence that a small amount of movement 

may have taken place along some of these fractures * * *. 

From the test-pit operations it is concluded that the mounds 

on which the oil seeps are located as well as the other mounds 

in the vicinity are not erosional remnants of consolidated 

bedrock. It is probable that they result from local frost 

action. Fissuring of the frozen ground accompanying the upheavals provided channels through which oil could escape from 

a reservoir below.

Nothing about the nature of the reservoir or the depth to 

bedrock could be determined from the test-pit studies.

AGE AND CORRELATION OF THE GUBIK 

FORMATION

MacNeil (1957, p. 108-109) tentatively correlated 

all fossil collections from unconsolidated surficial deposits west of the Colville River with the Gubik Formation but with the reservation that the formation might 

not all be of Pleistocene age. The fauna from the 

Colville Kiver and possibly from Skull Cliff he regarded as late Pliocene or early Pleistocene. The 

fauna, according to MacNeil, seems to be most closely 

related to a fauna occurring in the Pribilof Islands. 

These findings are not appreciably different from those 

of the earlier workers, whose reports he referred to.

MacNeil (1957, p. 108) also interpreted the fauna 

from the Colville River as equivalent to or possibly 

older than the fauna from Skull Cliff; both appear older 

than the fauna from the Meade River. Faunas from 

the Kukpowruk River and from Point Barrow are 

probably younger than the fauna from Meade River. 

The abundance of Macomas in the Gubik beds locally 

might distinguish the Pleistocene Gubik from Recent 

beach.sands, according to MacNeil (written communication, Jan. 4, 1957).

The order of age of the faunas agrees with the 

writer's interpretation of the sequence of deposition, but 

on the basis of geomorphic evidence the deposition of 

the Gubik did not require all the Pleistocene and late 

Pliocene. Upper Cretaceous marine rocks everywhere 

underlie unconf ormably the unconsolidated Gubik Formation west of the Colville River. The lowermost

Gubik sediments west of the Colville River are clearly 

post-lower Pliocene on the basis of fossils (MacNeil, 

1957, p. 108-109) and therefore are younger than the 

Sagavanirktok Formation of early Tertiary age east of 

the Colville River. The Sagavanirktok Formation was 

deposited from the gradually rising Brooks Range to 

the south (Payne and others, 1951), and temperate 

climates are implied by coal beds derived from organic 

material deposited in basins (Chaney, 1940). In contrast, poor sorting, erratics, and general texture and appearance of local parts of the Skull Cliff unit suggest 

that it may represent a marine-deposited till. Land 

ice would not necessarily have to carry the debris 

directly to its present resting place; ice rafting would 

suffice.

Assuming the Skull Cliff unit was deposited during 

glacial times, the problem is to determine which major 

subdivision of the Pleistocene it represents. This has 

not been accomplished. Detterman, Bowsher, and 

Dutro (1958) correlated the glacial sequence in the 

Brooks Range and glacial outwash in the Gubik in 

part with pre-Wisconsin glaciation but did not cite 

specific sections. Evidence for age of most of the 

Gubik Formation is inconclusive or conflicting. The 

evidence consists of modification of geomorphic features, carbon-14 dates of organic matter incorporated 

in the Gubik, marine invertebrate and terrestrial 

vertebrate fossils, archeologic finds, and rate of growth 

of ice wedges.

As pointed out by Smith and Mertie (1930, p. 48), 

the original surface features are most modified farthest 

from the sea, and those nearest the coast are affected 

least. This fact suggests that the Barrow unit must 

be younger than the Meade River unit, but it does not 

indicate a specific age or definite means of correlation 

with the Pleistocene glaciations. However, the textural 

and lithologic maturity of the Meade River unit in 

contrast with the Barrow or Skull Cliff units suggests 

nonglacial times or at least the absence of easily obtained 

elastics of great diversity of sizes and composition. 

Much reworking of the Meade River sands certainly is 

necessary for their formation, but no specific time can 

be allocated to the process. A few thousand years are 

sufficient; many tens of thousands of years conceivably 

are possible. Hence, either an intraglacial stade or an 

interglaciation might be represented.

Coniferous and deciduous driftwood is carried by 

marine currents today along the Alaskan coast from 

sources elsewhere in Alaska, Canada, and Russia (Giddings, 1952), and similar wood can also be found at 

depth in the Gubik and inland onto the foothills. H. 

W. Coulter (written communications, January 16 and 

28,1958) collected part of a driftwood spruce log from 

a depth of 16 feet in the Barrow unit 5 miles southwest
GUBIK FORMATION IN NORTHERN ALASKA 89

of Barrow, which has been carbon-14 dated as "more 

than 38,000 years." He mentioned that the log does 

not show much abrasion or weathering. Peat collected 

by K. M. Hussey at depths of 12 and 44 inches in sediments deposited in a lake 4 miles south-south west of 

the naval airbase was carbon-14 dated as 3,540±300 and 

9,100±260 years B. P., respectively. (Samples submitted by H. W. Coulter to the U.S. Geological 

Survey; written communication, December 4, 1959.) 

These three dates might be interpreted as bracketing 

that portion of the Barrow unit from a depth of 1 to 

16 feet. However, truncated ice wedges beneath the 

lake are almost identical in size to those surrounding 

the lake today. The present ice wedges surrounding 

the lake are growing actively, increasing width perhaps 

1 mm a year on the average (Black, 1952b) ; those beneath the lake are not. Thus, it does not seem reasonable 

to assign an age of thousands of years to the lake sediments. If the lake sediments were thousands of years 

old, a marked difference in size of the wedges would be 

apparent. Alternatively, "old" organic matter from 

the tundra must have caved into the enlarging lake at 

a more recent date. In any case the tundra in the vicinity of the lake must be several thousand years old. In 

partial corroboration Tedrow and Douglas 1 cited Carbon-14 dates of 10,600 to 10,900 years on organic matter 

from 2-foot depths in the soil on the emerged bar 1 mile 

inland from the airbase. If the oldest dates are approximately correct, the Barrow unit must represent 

much if not all of the Wisconsin Glaciation. One might 

then correlate the Meade River unit with the Sangamon 

Interglaciation and the Skull Cliff unit with the Illinoian Glaciation. What then happened during previous 

glaciations or interglaciations? Unfortunately, no evidence of early Pleistocene deposition has yet been found 

except for the correlation of the early Gubik invertebrate fossils with early Pleistocene or late Pliocene time. 

Archeological findings (Solecki, 1951) are only a few 

thousand years old. Pleistocene mammals, now extinct, 

lived as recently as 8,000 years ago (Sellards, 1952, p. 

115-116) and do not permit subdivision of the Pleistocene. The geomorphic evidence neither substantiates 

nor negates the paleontologic correlations. However, 

deposition during only part of the Pleistocene was 

needed for formation of the Gubik. It is obvious that 

further fieldwork is required to determine the age and 

correlation of the Gubik Formation.

GEOMORPHIC HISTORY OF THE GUBIK FORMATION

During the last part of Quaternary times, the Arctic 

coastal plain province of northern Alaska was the scene 

of shallow fluctuating seas, interrupted by brief emer1 Tedrow, J. C. F., and Douglas, I/. A., 1958, Carbon-14 dating of some 

arctic soils: Rutgers Univ., mimeographed note, 6 p.

gences of the land. Glaciation supplied some sediment 

to the Gubik Formation, at least indirectly. The history was exceedingly complicated in detail and cannot 

now be reconstructed except in gross outline. Smith 

and Mertie (1930, p. 48) pointed out:

the surface of this tract does not represent a single plain but 

instead is made up of a number of surfaces of erosion and deposition which have been formed during a long period of years and 

mark different stages of erosion and uplift. The characteristic 

feature of the whole province, however, is that practically everywhere its surface is formed of unconsolidated deposits that ha.ve 

been laid down mainly under marine conditions. These deposits 

have been uplifted and in part reworked and shaped by other 

agencies. Presumably at one time this province was similar 

to the present floor of the sea off this coast. Later it was uplifted and as soon as it rose above the sea was exposed to the 

same kinds of erosional and depositional processes that are 

even now tending to modify and shape its appearance. Many 

of its features therefore represent the inequalities that existed 

on its surface when it was part of the floor of the sea, others 

are the gullies formed by the run-off from the latest shower of 

rain, and between these two extremes are all gradations.

On the whole, however, in a geologic sense the province is 

young, and there has not yet been time for the present processes 

to remodel its features to fit existing conditions. Consequently, 

large tracts have not yet acquired thorough drainage, and ponds 

and lakes that fill old depressions are numerous on the poorly 

drained uplands. Because the inland part of the coastal plain 

has been longest above the sea, its original surface features are 

most modified, and the parts nearest the coast have been affected 

least.

In large measure, the foregoing statement is as appropriate today as it was several decades ago. Turf is 

found 4 and 10 feet beneath the sea in the Point Barrow 

spit, and emerged bars and beaches are found literally 

by the dozen at elevations of 2 to 600 feet from the back 

shore to the foothills. Tracing of the boundary between 

the foothills and the coastal plain reveals in many places 

a wave-cut cliff that is warped from a point near sea 

level on the west near Cape Beaufort to 600 feet elevation south of Barrow and down to a few tens of feet near 

Umiat. Uplift of the coastal plain obviously has not 

been uniform in either time or place, but details are 

lacking. Moreover, if the sediments of the Meade River 

unit are pre-Wisconsin in age, as seems possible, many 

tens of thousands of years have passed with little evidence remaining or recognized of the events that 

transpired since its deposition.

The major streams of the coastal plain apparently 

are largely consequent upon the original upwarped surface and fan outward from the crest of the arch. In 

places valleys many tens of feet deep have been carved 

through the Gubik and for some feet into the underlying 

Cretaceous rocks. Emerged bars, beaches, lagoons, and 

other coastal features however, are still fresh and 

readily recognized. Associated with the emerged 

coastal features and situated between them are thou-
90 EXPLORATION OF NAVAL PETROLEUM RESE'RVE NO. 4, ALASKA, 1944-53 

sands of oriented lakes and drained-lake basins. Many 

of the lakes are shallow and merely truncate the ubiquitous ice wedges. They are enlarging mostly by caving 

and are true thermokarst lakes. As the truncated 

wedges under the very shallow lakes are only slight.ly 

smaller than those under the tundra adjacent, these 

lakes cannot be more than a few hundred years old. 

Other deep lakes have thawed out deep basins in the 

permafrost and seemingly are many thousands of years 

old. The apparent similarity of mn,ximum size of ice 

wedges over the whole coastal plain implies that they 

started to grow at about the same time. Only the more 

recent constructional features, such as the Point Barrow spit, emerged lagoon near Barrow, and the many 

swampy lakebeds have more youthful ice wedges. 

Dated archeological sites (Collins, 1933 and 1951; 

Stefansson, 1914, p. 393-394; and Wissler, 1916, p. 440) 

at Barrow are cut by ice wedges and tend to confirm the 

validity of the dates of the ice wedges, which on the 

Point Barrow spit are 800 to 1,000 years old. On the 

tundra, average wedges, 1 to 3 meters wide, are on the 

order of 1,000 to 3,000 years old. Most wedges need less 

than 5,000 years to form, although some may well be 

twice that old. Buried wedges, thoSe whose tops were 

truncated by deep thaw, are common. Conditions 

favorable for producing ice wedges obviously cannot 

be traced back much beyond 10,000 years without a 

break, yet cold climates and permafrost which extends 

to depths of more than 300 meters have been present 

much longer. Structures interpreted as fossil ice 

wedges, ice-shoved ridges, and fillings around ice blocks 

attest to cold climates and permafrost during deposition 

of at least 20 feet of the upper part of the Barrow unit, 

a time apparently encompassing several tens of thousands of years. 

Rapid retreat of the coast (MacCarthy, 1953) by 

wave action during the summer is obvious. Wind 

action today (Black, 1951) moves sand effecti,·ely and 

distributes loess over much of the coastal plain. 

Typical dune crossbedding and wind-sorted and frosted 

sand grains are widespread in the Meade River unit. 

Mass movement of material on slopes is very rn,pid. 

The solifluction mantle near Umiat studied by Livingstone (1955, 1957) seemingly spans about the same time 

as the currently active ice wedges. These and other 

geomorphic processes are rapidly modifying the Gubik 

sediments where they are exposed. However, the 

subaerial processes now affecting the Gubik Formation 

seemingly did not all act with their present intensity, 

if indeed they acted at all, during the brief emergences 

of the coastal plain. Much more information must be 

obtained before the statements of Smith and Mertie 

( 1930) can be modified signi'ficantly. 

ENGINEERING SIGNIFICANCE OF THE GUBIK 

FORMATION 

The Gubik Formation, <.:onsisting of unconsolidated 

fine-grained materials, does not in itself produce prob. 

lE>ms in engineering any more llllllStutl than do similar 

ma.terials in conterminous U nited States. However, 

the fact that the formation is perennially frozen and 

generaJly conta ins more ice than pore space is of great 

engineering significance. Permafrost, by prohibiting 

ground-water infiltration a.nd migration, precludes the 

drilling of shallow wells for wa.ter or the installation 

of septic tanks for sewage disposal. Excavations into 

frozen ground cannot be made with the same ease or 

even with the same equipment as in unfrozen material~ 

Moreover, const.ruction in ot· on permafrost must always 

be designed in such a way as to prohibit thawingof the 

underlying ice and subsequent failure of the structure. 

Many of the engineering problems regarding perma· 

frost. have been met and solved; others are still to be 

met. Some problems in engineering geology ca used by 

permafrost in the. Arctic coastal plain have been re· 

viewed by Black ( 1957), Reed ( 1958), and other per· 

tinent. references cited. The major problems pertain 

to overland transportation, construction, water suppl)· 

and sewage disposa l, and drilling for and production of 

oil and gas. 

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· 

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GUBIK FORMATION IN NORTHERN ALASKA 91 

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