2010

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the National Park Service

Surficial Geologic Map of the Noatak National Preserve, 

Alaska

By Thomas D. Hamilton

Pamphlet to accompany

Scientific Investigations Map 3036

Bluff exposure along Noatak River, with water-filled kettle depressions in background. Amphitheater-like gully 

heads were created by thaw and flowage of ice-rich permafrost. Bluff exposures along Noatak River and its 

tributaries are described in Hamilton, 2009. 
Conversion Factors

Multiply By To obtain

Length

millimeter (mm) 0.04 inch (in.)

centimeter (cm) 0.4 inch (in.)

meter (m) 3.28 foot (ft)

kilometer (km) 0.62 mile (mi)
i

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

Physical Setting.....................................................................................................................................1

History of Investigations......................................................................................................................2

The Map..................................................................................................................................................2

Bedrock Surface Forms................................................................................................................................2

The Pleistocene Record................................................................................................................................3

Glacial, Lacustrine, Eolian, and Fluvial Interactions.......................................................................3

Glacial Nomenclature ..........................................................................................................................4

Glacial Lakes..........................................................................................................................................4

Middle Pleistocene and Older(?) Glaciations ..................................................................................5

Late Pleistocene Glaciations .....................................................................................................6

Glaciations and related events of Itkillik I age...............................................................7

Glaciation and related events of Itkillik II age ...............................................................8

Glaciation in the Baird Mountains ...................................................................................9

The Pleistocene-Holocene Transition and Subsequent Holocene Events...........................................9

Acknowledgments.......................................................................................................................................10

Description of Map Units............................................................................................................................11

Surficial Deposits ...............................................................................................................................11

Fan Deposits ...............................................................................................................................11

Alluvium.......................................................................................................................................11

Terrace Deposits........................................................................................................................12

Colluvial Deposits.......................................................................................................................12

Sand, Silt, and Organic Deposits.............................................................................................13

Lacustrine, Glaciolacustrine, and Glacial-Marine Deposits ..............................................14

General ...............................................................................................................................14

Within Brooks Range .......................................................................................................14

Mission Lowland...............................................................................................................15

Glacial Drift and Ice-Contact Gravel ......................................................................................15

Late Holocene glaciation (Neoglaciation)....................................................................15

Itkillik glaciation ................................................................................................................15

Sagavanirktok River glaciation.......................................................................................16

Cutler glaciation................................................................................................................17

Sagavanirktok River or older glaciation........................................................................17

Anaktuvuk River glaciation .............................................................................................17

Glacial Outwash and Inwash...................................................................................................17

Itkillik glaciation ................................................................................................................17

Sagavanirktok River glaciation.......................................................................................18

Cutler glaciation................................................................................................................18

Bedrock Surface Forms.....................................................................................................................18

References Cited..........................................................................................................................................19

Table 1. Glacial advances from the De Long Mountains and equivalent glacial advances in the 

central Brooks Range. MIS, marine isotope stage.....................................................................4

Contents
This page intentionally left blank.
1

Introduction

Physical Setting

Most of the Noatak National Preserve (NNP) is centered 

on the Noatak River valley, which trends westward parallel to 

the structural grain of the Brooks Range for about 250 km from 

the Preserve boundary to the mouth of Kelly River. At this 

point, the Noatak bends sharply into a southward course that 

extends about 100 km farther to the coast and enters Kotzebue 

Sound opposite the town of Kotzebue. Through its west-trending course, the Noatak valley floor forms broad to narrow lowlands that separate the De Long Mountains to the north from 

the Baird Mountains to the south (Burch, 1990, p. 196–201). 

The map area through this sector extends between drainage 

divides that bound the Noatak drainage system, separating it 

from streams that flow north into the Arctic Ocean and south 

into the Kobuk River, respectively. The south-trending segment 

of the Noatak River skirts the west end of the Baird Mountains 

and lies at or just beyond the western boundary of the NNP.

The Noatak’s valley widens into broad basins in two 

places. The upper basin, termed the Aniuk Lowland by Wahrhaftig (1965), occupies much of the eastern portion of the 

NNP. The lower basin, Wahrhaftig’s (1965) Mission Lowland, 

is confined to the south by the Igichuk Hills, a bedrock ridge 

transverse to the course of the Noatak River a short distance 

above its mouth. The two lowlands and intervening deeply 

incised, narrow valley floor divide the Noatak drainage system 

into three sharply contrasting sectors. The easternmost sector, 

about 145 km long and centered on the Aniuk Lowland, 

extends downvalley to the Nimiuktuk River confluence. It is 

bounded by rugged highlands of the Brooks Range to the south 

and southeast and by generally lower Brooks Range uplands 

to the north. The principal tributary to this upper sector of 

the Noatak River is the north-flowing Cutler River system. 

Pleistocene-age glaciers flowed into the Aniuk Lowland from 

nearly all directions. During middle and late Pleistocene times, 

valley glaciers extended southeastward out of the De Long 

Mountains into the west end of the lowland. These glaciers 

repeatedly dammed the Noatak River, forming glacial lake 

Noatak (Hamilton and Van Etten, 1984; Hamilton, 2001). 

During the older and more extensive glacial advances, much of 

the Aniuk Lowland filled with proglacial lakes, which at various times overflowed northward into the Colville River system 

by way of Howard Pass and southward through upper Hunt 

River into the Kobuk River valley. At other times, the lakes 

discharged westward, skirting south of the ice margin to enter 

the lower valley of the Noatak River. A large valley glacier that 

originated in highlands near the head of the Noatak drainage 

system flowed westward to terminate in the proglacial lake at 

those times, as did smaller glaciers that flowed southward and 

northward into the basin. Numerous tall bluff exposures along 

the Noatak River and its principal tributaries record multiple 

lake stages separated by interglacial fluvial deposits (Hamilton, 

2001, 2009).

Through the central sector, which begins at the the 

Nimiuktuk River confluence, the Noatak River turns sharply 

southward and then flows west again for about 60 km through 

a relatively narrow rock-walled valley that broadens farther 

west into the upper part of the Mission Lowland. The river was 

displaced southward into this sector by glaciers that originated 

in upper valleys of the De Long Mountains and that flowed 

southward through five principal drainage systems: the Nimiuktuk, Kaluktavik, Kugururok, Avan, and Cutler. Glacial-lake 

deposits are present in a narrow belt along the Noatak valley 

floor, and lake deposits broadly cover the floors of four of those 

valleys. However, glacial-lake deposits are absent from Avan 

River valley, which supported active glaciers until the close 

of the Pleistocene. Bluff exposures through this sector of the 

Noatak valley floor reveal glacial-lake deposits and abundant 

fluvial sediments that record stages of postglacial river downcutting (Hamilton, 2009).

The westernmost sector, the Mission Lowland, probably 

was occupied by lakes during middle and late Pleistocene 

times but capping sediments of loess and alluvium obscure 

much of their record. During middle Pleistocene time, glaciers issuing from western valleys of the De Long Mountains 

probably blocked an earlier westward course of the Noatak 

River that extended directly into the Chukchi Sea (as illustrated 

by McCulloch, 1967), diverting the river southward into its 

present position. During that interval, lakes probably formed 

behind massive moraine dams during times of glacier recession. Younger lake episodes may be slackwater events (as 

described by Waitt, 1980) that formed when outburst floods 

from glacier-dammed lakes farther upvalley were confined for 

periods of days or perhaps weeks behind the Igichuk Hills. 

Slackwater deposits also may have formed during the Holocene, when rapid sea-level rise flooded Kotzebue Sound and 

raised the base level for the lower Noatak River. River-bluff 

exposures generally are absent from the Mission Lowland 

because of Holocene alluviation; consequently the sediments 

that underlie the widespread blanket of loess and fine-grained 

alluvium are seldom evident.

The map area has an arctic climate, with long cold winters and short cool summers (Childers and Kernodle, 1981). 

Tundra vegetation, with low shrubs present along stream 

courses, predominates through the upper basin of the Noatak 

River. Progressively farther downvalley, riparian stands of 

cottonwood (Populus balsamifera) and then white spruce 

(Picea glauca) become increasingly dominant along the 

valley floor (Viereck and Little, 1975). Wetlands cover much 

of the Aniuk and Mission Lowlands (CAVM Team, 2003), 

and the Mission Lowland bears a mosaic of spruce stands and 

moist tundra vegetation. Most of the Noatak drainage system 

is included within the Arctic Foothills ecoregion of Gallant 

others (1995), but this seems to me a misleading generalization. The Noatak valley floor is underlain by continuous 

permafrost, which generally is ice-rich and lies at shallow 

depths. Related surface features such as ice-wedge polygons 

are widespread, and pingos are present locally in the Aniuk 

and Mission Lowlands. Permafrost generally is also continuous beneath surrounding uplands, but its ice content and 

depth below the surface are more variable there (Ferrians, 

1965; Brown and others, 1997).
2

History of Investigations

Initial geologic study of the Noatak River valley was 

undertaken in 1911 by a U.S. Geological Survey (USGS) field 

party led by Philip S. Smith that portaged into the upper Noatak 

drainage and then traversed the river to its mouth (Smith, 1913). 

More detailed helicopter-supported bedrock geologic mapping 

was carried out later by the USGS. This work culminated in 

geologic maps that covered entire 1:250,000-scale quadrangles 

(Karl and others, 1989b; Mayfield and Tailleur, 1978) or portions of such quadrangles at larger scales (Curtis and others, 

1984; Ellersieck and others, 1984; Dover and others, 2004; 

Mayfield and others, 1984, 1987, 1990). A derivative map of 

construction materials within the Baird Mountains quadrangle 

was compiled by Combellick and others (1993).

Regional syntheses of western Brooks Range geology 

include Mayfield and others (1988), Till (1989), Moore and 

others (1994), Dumoulin and others (2004), Slack and others 

(2004), and Young (2004). Other geologic studies have dealt 

with the igneous and metamorphic rocks of the map area 

(Nelson and Nelson, 1982; Boak and others, 1987; Karl and 

others, 1989a; Till and others, 1988; Till, 1989; Saltus and 

others, 2001). Mineral-resource data for individual quadrangles 

of the NNP region have been compiled by Mayfield and others 

(1983), Dover (1997a,b), and Williams (2000).

Surficial geology of the western Brooks Range was compiled from aerial photographs in 1960 by A.T. Fernald, H.W. 

Coulter, and E.G. Sable of the USGS. Their data were incorporated into statewide maps of surficial geology (Karlstrom and 

others, 1964) and glacial limits (Coulter and others, 1965). Later 

field mapping of the upper Noatak River valley (Hamilton, 

1981, 1984a,b) led to recognition of a series of large ancient 

lakes created by glaciers that originated in the De Long Mountains and flowed southward to dam the Noatak River (Hamilton 

and Van Etten, 1984). Subsequent detailed study of river bluffs 

through this sector of the Noatak valley resulted in recognition 

and dating of interstadial deposits of middle Wisconsin age 

(Hamilton and others, 1987), identification of the Old Crow 

tephra, a widespread interglacial marker bed (Hamilton and 

Brigham-Grette, 1992), and paleoecologic analyses of locally 

rich interglacial insect and vegetation records (Elias and others, 

1999; Edwards and others, 2003). An overview of the depositional record exposed in these bluffs (Hamilton, 2009) reveals a 

complex history of interrelated glacial advances, stages of lake 

formation, and episodes of river downcutting (Hamilton, 2001, 

2009).

The Map

The surficial geologic map of the Noatak National Preserve 

(NNP) is a compilation that incorporates portions of four published USGS maps (Hamilton, 1980, 1981, 1984a,b), a USGS 

Open-File Report (Hamilton, 2003), and unpublished field mapping. It covers an area of about 28,700 km2, and includes parts 

of eight 1:250,000-scale quadrangles.

The mapped area generally terminates at NNP boundaries, which generally follow the sharp divides that separate 

the Noatak drainage system from north-flowing drainages of 

the Alaskan North Slope and south-flowing tributaries to the 

Kobuk River. The mapping extends short distances beyond 

those boundaries where passes across divides were traversed by 

glaciers issuing from the Noatak drainage or by overflow waters 

from glacial lake Noatak. Along the western edge of the map, 

where the NNP boundary is unrelated to topographic features, I 

have extended the mapping to the nearest natural boundary, the 

active channel of the Noatak River, and have mapped beyond 

that limit only in places where surficial deposits are essential for 

understanding regional geology.

I have used the metric system for all heights and distances 

cited on the map and in this pamphlet. Metric-English conversion values are printed inside the pamphlet’s front cover for 

ready reference. However, in the case of former lake heights 

and other altitude data, the original measurements generally 

were taken from helicopter altimeters and USGS topographic 

maps which recorded feet above sea level; and these measurements were later converted into meters. In addition, the topographic base used for the NNP map is derived from those USGS 

topographic maps, which show contours in feet. For these reasons, altitudes are presented in meters followed by the original 

readings in feet for the convenience of map users.

Bedrock Surface Forms

Rather than subdivide bedrock on the basis of age and 

lithology, I have chosen to create six bedrock divisions that 

reflect surface form. These units should be of value as indicators 

of (1) scenic attributes, (2) landslides and other natural hazards, 

(3) ancient lake margins, (4) former drainage channels, (5) loess 

sources and distribution, and (6) the source areas, flow routes, 

and outer limits of ancient glaciers. Some units serve as guides 

to the presence of unweathered bedrock exposures, which may 

be of particular value in areas blanketed by otherwise widespread and unbroken lake sediments or other surficial cover.

Alpine bedrock (unit Ba) generally consists of resistant 

rock types, such as conglomerates, massive carbonates, and 

intrusive igneous rocks, which form relatively high, rugged 

uplands. In addition, late Pleistocene glacial erosion has further 

steepened valley walls, sharpened ridge crests, and carved 

steep-sided cirque basins at valley heads. This unit therefore 

provides a good guide to source areas and distribution of former 

glaciers. Its steep glacier-carved slopes are subject to rockfalls, 

landslides, snow avalanches, and other alpine hazards.

Bedrock exposed by stream erosion (unit Be) consists of 

narrow strips of bedrock that extend along former meltwater 

channels or routes of glacial-lake discharge, and also more 

extensive tracts of bedrock, such as along Aklumayuak Creek 

and parts of the Noatak River, that underwent late Pleistocene 

downcutting. The mapped distribution of this unit provides a 

useful guide to Pleistocene drainage changes, and would be 
3

helpful in locating bedrock exposures in areas generally covered 

by surficial deposits.

Glacier-scoured bedrock (unit Bg) has been overridden and 

scoured by glacier ice. Areas thus designated serve as useful 

indicators of the extent and distribution of former glaciers. 

Because the glaciated surfaces commonly are streamlined 

and channeled in the directions of glacier flow and meltwater 

drainage (shown by symbols on the map), they also serve as 

flow-direction indicators. Glaciated bedrock generally yields 

excellent rock exposures in areas where other rock surfaces are 

weathered, frost-shattered, or silt-covered.

Silt-covered bedrock (unit Bs), designates upland surfaces that are largely obscured by fine-grained sediments or 

weathering products. On adjoining hillsides and valley walls, 

solifluction has transported and mixed these deposits, forming extensive aprons of rubbly or organic silt that thicken 

downslope. Areas of silt-covered bedrock generally were 

not glaciated during late Pleistocene time. They are common 

downwind from glacier-dammed lakes that served as sources of 

windblown silt (loess) when the lakes were freshly drained and 

their floors not yet revegetated. Lake beds that were exposed 

repeatedly by outburst floods would have been especially effective loess sources. Within the Baird Mountains, some low-lying 

areas of silt-covered bedrock more distant from Pleistocene lake 

beds are underlain by rock types such as phyllite that weather 

readily to yield abundant fine-grained detritus.

Wave-eroded bedrock (unit Bw) has been scoured by wave 

action along the margins of ancient glacier-dammed lakes. 

Because it occurs only locally around former lake margins, it 

may provide a useful guide to wind directions at times when 

the lakes existed. Wave-eroded bedrock also is best developed 

where fetch (the open-water distance across which the wind 

is able to generate waves) was greatest. In addition, because 

bedrock-surface forms can persist much longer than unconsolidated deposits, wave-scoured bedrock commonly provides the 

best guide to the most ancient lake levels.

Undifferentiated bedrock (B) generally designates rock 

masses that are intermediate in character between the other bedrock surface forms or are assemblages of diverse surface forms 

that are too small to map individually.

The Pleistocene Record

Glacial, Lacustrine, Eolian, and Fluvial 

Interactions

Surficial geologic units and their relations within the eastern half of the map area are compatible with the glacial-lacustrine-fluvial model described previously (Hamilton, 2001, 2003) 

for the upper Noatak basin. During each of several succeeding 

Pleistocene glaciations, glaciers developed in cirque-headed 

valleys within the upper Noatak drainage system and within the 

De Long Mountains. Glaciers generated within the De Long 

Mountains expanded down south-trending valleys and spread 

into lobes within lowlands along the Noatak River. Dammed by 

the lobes, large lakes formed and inundated the Aniuk Lowland 

basin for as much as 50 km upvalley from the moraine barriers 

(Hamilton, 2001). Although some of the older and larger lakes 

had outlets to the north and south by way of Howard Pass and 

Hunt River, most lakes probably filled and emptied repeatedly 

as their ice dams eroded or became buoyant (Clague and Evans, 

1994; Walder and Costa, 1996; Hamilton, 2001). The resulting 

glacial outburst floods would have surged westward down the 

Noatak’s narrow, rock-walled valley where the river is deflected 

south of the De Long Mountains, and then spread more widely 

across the Mission Lowland. Outburst-flood drainage of the glacier-dammed lakes must have occurred with greater frequency 

as ice thinned or retreated toward the close of a glaciation, with 

the lake refilling each time to a lower surface level. Each time 

a lake drained, its newly exposed floor was swept by winds that 

entrained fine-grained sediments and deposited them downwind 

as loess. The Noatak River re-established its course across the 

lake floor early in each interglacial, then cut down progressively 

to a level near that of the present day. The river bluffs created 

by this downcutting exhibit early-interglacial fluvial channel 

and floodplain deposits at levels several tens of meters above 

present river level, whereas full-interglacial fluvial deposits 

appear at or slightly below the modern river (Elias and others, 

1999; Edwards and others, 2003; Hamilton, 2001, 2009). These 

interglacial fluvial deposits were buried and preserved beneath 

till-like sediments that formed during subsequent glaciations 

and glacio-lacustrine episodes.

Through the Noatak’s remaining westward course, the 

river is more closely confined between the De Long and Baird 

Mountains. Glaciers flowed southward down major valleys of 

the De Long Mountains in a radiating pattern: southeastward 

near the Nimiuktuk River valley, and south-southwestward near 

the Kelly River’s drainage system. Arcuate moraine ridges that 

are nearly obscured beneath blanketing lake deposits indicate 

blockage of the Noatak River at the mouths of most major 

valley systems. Lake deposits extend up most of these valleys 

for distances as great as 50 km, attesting to continued blockage 

of the drainage network during and perhaps following deglaciation. Downcutting of the Noatak River by as much as 50 m took 

place during the Holocene, and perhaps extends back into the 

latest Pleistocene as well.

Smaller glaciers developed on local highlands within the 

Baird Mountains but were mostly restricted to valley heads near 

the Noatak-Kobuk divide. Glaciers locally crossed divides into 

upper valleys of the Kobuk drainage system but generally did 

not extend northward far enough to intersect lowlands along the 

Noatak River. Parts of the Baird Mountains bear heavy loess 

cover that may have been largely derived from the floors of 

drained glacial lakes farther to the north.

The remaining stretch of the Noatak River may once have 

continued westward to the Chukchi Sea but it was diverted into 

its present southward course by glacier ice and (or) moraine 

barriers. Lakes may have filled the Mission Lowland during or 

after the drainage diversion, confined behind the transverse bedrock ridge near the river’s mouth and blocked by moraine dams 

to the west. Although any lake deposits on the lowland floor are 

buried beneath blankets of loess and fine-grained alluvium, their 
4

probable subsurface presence is indicated by delta and fan-delta 

deposits, wave-cut notches, beach ridges, and overflow channels 

around the basin’s margins.

Glacial Nomenclature

A consistent set of terms has been employed for glacialgeologic mapping through the central Brooks Range (Hamilton, 1986 and references therein) as well as for mapping the 

eastern half of the map area (Hamilton, 1980, 1981, 1984a,b). 

The Anaktuvuk River and Sagavanirktok River glaciations are 

broadly equated with multiple glacial advances of early and 

middle Pleistocene age, respectively; the Itkillik glaciation is 

equated with multiple advances during the late Pleistocene 

(table 1). However, glaciers in the De Long Mountains were 

nourished in part from moisture sources in the Bering Sea, and 

they probably responded somewhat differently from central 

Brooks Range glaciers during each glacial cycle. Younger glacial advances in the De Long and Baird Mountains are broadly 

equated with advances of the Itkillik succession in the central 

Brooks Range, but an older and much more extensive glacier 

advance has been designated the Cutler advance (Hamilton, 

2001) because its relationship to glacial events of middle Pleistocene (Sagavaniktok River) age in the central Brooks Range is 

unclear. The Cutler advance may correlate more closely with the 

glacial advance that constructed the Baldwin Peninsula moraine 

near Kotzebue, which Huston and others (1990) believe formed 

during late-interglacial rather than full-glacial time owing to 

nearby moisture sources provided by interglacial flooding of the 

Bering platform.

Throughout the map area I have employed the unit designations used for late Pleistocene (Itkillik) glaciations in the 

central Brooks Range. This facilitates comparison with mapped 

areas farther east and also permits the uniform use of generalized designations (for example, unit id) in cases where more 

age-specific designations (such as id1, id2, and id3) are not 

appropriate for glacial deposits that clearly are of late Pleistocene age. However, many glacial deposits through the central 

part of the map area are directly traceable into end moraines 

that are named for tributary drainages that join the Noatak River 

close to where the moraines cross the valley center (Hamilton, 

2001). I consequently employ a double set of names in the mapunit descriptions: the local moraine name followed in parentheses by its probable central Brooks Range equivalent (see 

table 1). For middle Pleistocene glaciations, I have employed 

the Sagavanirktok-Anaktuvuk terminology for central Brooks 

Range glaciers of the upper Noatak drainage and the CutlerOlder glaciation succession for glaciers issuing from the De 

Long Mountains.

Glacial Lakes

The Pleistocene-age lakes in the map area formed behind 

both glacial and moraine barriers. Lakes that were dammed 

by active glaciers filled and drained dramatically rather than 

remaining at static levels. Other lakes confined behind moraine 

barriers were more stable, but their surfaces lowered progressively as the moraines eroded. Consequently, the shoreline 

features associated with these varying lake surface levels are 

weakly developed and generally difficult to trace. The deposits 

of the former lakes are recognizable as poorly drained, icerich, fine-grained sediments that blanket valley floors and thin 

upward on lower valley sides, generally wedging out at consistent altitudes. Fan-delta deposits are common at the mouths of 

tributary valleys; they splay into unusually broad, low-gradient, 

uniformly fine-grained deposits below the levels of the former 

lakes. Wave-cut notches are present along the inner flanks of 

moraines near Nimiuktuk River and along bedrock exposures 

in the Aniuk and Mission Lowlands, localities where unusually great fetch (span of open water) would have allowed wave 

Table 1. Glacial advances from the De Long Mountains and equivalent glacial advances in the central Brooks 

Range. MIS, marine isotope stage.

De Long

Mountains

Map

unit

Central

Brooks Range Age

Neoglaciation nd Neoglaciation Late Holocene

Unnamed id3 Late Itkillik II readvance Late Wisconsin (MIS 2)

Avan advance id2 Itkillik II phase Late Wisconsin (MIS 2)

Unnamed id1C None recognized Early Wisconsin (MIS 4)

Anisak advance id1B Itkillik IB phase Early Wisconsin (MIS 4)

Makpik advance id1A Itkillik IA phase Late interglacial (MIS 5d–5a)

Okak advance ---- Sagavanirktok River (late phase) (sd2) Middle Pleistocene

Cutler advance cd Sagavanirktok River (undifferentiated) (sd) Middle Pleistocene

Unnamed older drift od Sagavanirktok River or Anaktuvuk River (ad) Middle or early Pleistocene
5

action to be particularly effective. Abraded and terraced bedrock 

surfaces also attest to the effectiveness of wave erosion in the 

two lowlands. Rare linear outcrops of well rounded fine gravel 

are interpreted as probable beach ridges. End moraines in some 

valleys become diffuse below levels that probably represent 

contemporaneous lake stands; other end moraines were wavewashed, leaving resistant pavements of erratic boulders on 

their surfaces. The upper limits of those pavements mark the 

maximum heights of lake stands that accompanied or followed 

abandonment of the moraines by glaciers.

Three principal lake stages are recognized in the map 

area, and a series of younger and lower lake stands occur in the 

Mission Lowland. The lake stages, which can be dated approximately by their interrelationships with moraines, form an important part of regional drainage history, controlling the locations 

of overflow channels and the timing of glacial outburst floods. 

The fine-grained lake deposits cause valley floors and lower 

valley sides to be poorly drained, resulting in shallow ice-rich 

permafrost, active solifluction, and other frost-related processes. 

The presence or absence of lake deposits of a given age can 

indicate the extent of contemporaneous glaciation, and former 

centers of glaciation are indicated by postglacial isostatic uplift 

of initially horizontal lake planes. The upper limits of deformed 

lake deposits typically become progressively higher eastward 

toward the heavily glaciated central Brooks Range and also 

northward toward the most intensely glaciated part of the De 

Long Mountains.

Middle Pleistocene and Older(?) Glaciations

Most bedrock types within the map area weather rapidly, 

and erratic stones consequently are rare on surfaces older than 

late Pleistocene. Thick deposits of windblown silt, derived from 

the beds of newly drained lakes, also cover many of these older 

surfaces. For these reasons, limits of glaciations older than late 

Pleistocene are difficult to determine across upland areas, and 

boulder weathering and other physical characteristics cannot 

be used to distinguish between glacial deposits or glaciated 

bedrock surfaces of different middle Pleistocene and older ages. 

In lowland areas, end moraines of middle Pleistocene age commonly become diffuse where glacier termini presumably began 

to float in glacier-dammed lakes. Elsewhere, glacial moraines 

are covered by thick blankets of younger glacial-lacustrine sediments and appear only as broadly arcuate divides between the 

networks of minor streams.

Broad U-shaped troughs that cross drainage divides along 

the north and south boundaries of the NNP may be among the 

oldest glacial features recognized in the map area. Remnant 

patches of drift are evident on the floors of some passes, and 

bedrock abraded by glacier ice (unit Bg) commonly is present 

in and around the passes. These ice-abraded surfaces exhibit 

smoothed and streamlined ridges, faceted valley walls, and 

adjoining beveled uplands. The troughs along the northeast 

margin of the map area were generated by ice issuing from local 

centers of glaciation between Howard Pass and Anisak River. 

Farther west, troughs probably were carved by outlet glaciers 

from an extensive ice cap that covered much of the highlands 

between Nimiuktuk and Kelly Rivers. The troughs along the 

western part of the map area’s south margin may have been 

outlets from smaller individual glacier complexes that developed on prominent highlands. Drift patches and isolated erratic 

stones, which must originally have been present on these icesculpted surfaces, evidently were eradicated during a long span 

of postglacial weathering.

The Arctic Foothills Province beyond the northeast part of 

the map area contains an extensive record of early Pleistocene 

and late Tertiary glaciations, including evidence that the Noatak 

River once flowed north through Howard Pass before being 

diverted into its present westward course. This information is 

available elsewhere (Hamilton, 1984b, 1986) and will not be 

discussed further here.

An extensive blanket of featureless drift (unit od) that lies 

beyond Cutler-age deposits in the south-central part of the map 

area is inferred to represent a glaciation of early or middle Pleistocene age that preceded the Cutler advance. This drift is most 

extensive south of the Noatak River in the area between Cutler 

River to the east and the head of Aklumayuak Creek to the west.

Middle Pleistocene glacial deposits assigned to advances 

of Sagavanirktok River age are present locally through the 

eastern part of the map area. The largest glacier issued from 

the central Brooks Range and extended westward down the 

upper Noatak valley into the eastern part of the Aniuk Lowland. 

However, its drift is rarely exposed and generally occurs as 

subsurface features buried beneath lake deposits. The age relations between Sagavanirktok River glaciations and the Cutler 

advance are uncertain.

The Cutler advance represents the most distinctive glacial 

event of the middle Pleistocene. Its prominent end moraine, 

which intersects the Noatak River near the mouth of Cutler 

River (unit cd), was originally assigned to the late Pleistocene Itkillik glaciation (Hamilton, 1984b), but subsequent 

stratigraphic studies of bluff exposures along the Noatak 

River showed that deposition of this moraine preceded the last 

interglaciation (Hamilton, 2001). It may be correlative with 

the middle Pleistocene glacial advance described by Huston 

and others (1990) that created the massive Baldwin Peninsula 

moraine complex and with the silt-covered glacial and glacialmarine deposits (units us/d? and si/cgm) shown east of the 

Noatak’s mouth along the north shore of Hotham Inlet.

South of the Noatak River, the Cutler moraine is traceable 

almost continuously westward from the mouth of Cutler River 

past Lake Kangilipak and into uplands opposite the mouth of 

Nimiuktuk River. Farther west, opposite the mouth of Kaluktavik valley, subdued drift that extends southward into the 

Baird Mountains may also be of Cutler age. Glacier-scoured 

bedrock and glacier-shaped alpine topography that trend southsouthwestward across the west end of the Baird Mountains in 

the western part of the map area indicate that a second major 

ice lobe issued from Kugururok valley and flowed as far as 

the upper drainage network of Agashashok River. At least one 

minor ice tongue continued farther south, crossing a drainage divide into the upper valley of Squirrel River. A confluent 

glacier that issued from the Kelly drainage system probably 
6

flowed southward down the Mission Lowland to at least the 

Eli River area; its deposits are best exposed west of the Noatak 

River at locations well beyond the western boundary of the 

NNP, and therefore are incompletely shown on the map. These 

sets of glacial deposits and ice-shaped bedrock features outline 

prominent glaciers that flowed from the De Long Mountains 

southeastward up the Noatak River valley, southward into the 

Baird Mountains, and southwestward into the Mission Lowlands; the glaciers overrode most of the Noatak River valley 

from the Cutler River confluence nearly to its mouth. A glacial 

advance of this magnitude must have been generated by an ice 

cap over much of the De Long Mountains rather than by individual valley glaciers.

North of the Noatak River, drift of probable Cutler age outlines a large glacier that flowed southeastward from the upper 

valley of Nimiuktuk River, probably draining part of the eastern 

margin of the inferred De Long Mountains ice cap. The glacier 

probably overrode and scoured bedrock through the western 

part of the Iggiruk Mountains at this time because the orientations of grooved and streamlined rock surfaces are consistent 

with a southeasterly ice-flow direction. The drift, ice-scoured 

features, and associated meltwater channels are assumed to 

correlate with the Cutler moraine, but some of the lower-lying 

deposits just beyond Itkillik ice limits near New Cottonwood 

Creek may have formed later as part of the Okak end moraine, 

a subsurface feature which intersects the Noatak River at Okak 

Bend (Hamilton, 2001). Because thick glaciolacustrine deposits 

cover most of the intervening basin floor north of the Noatak 

River, surface exposures of glacial deposits are rare and correlations with the Cutler and Okak end moraines are uncertain.

Although a glacier-dammed lake of Cutler age must have 

filled the Aniuk Lowland, its deposits have been either largely 

obliterated by later glacier advances and stream erosion or 

covered by younger lake sediments. Lake deposits of this age 

(unit cgl) are recognized only in the upper valleys of Cutler and 

Anisak Rivers. Their upper limit increases eastward from about 

470 m (1525 ft) above sea level (asl) to about 510 m (1680 ft) 

asl across the Aniuk Lowland, probably reflecting postglacial 

isostatic uplift. The water plane of a possibly interconnected 

lake in the upper Anisak drainage also rises northward to a maximum altitude of about 500 m (1650 ft) asl, probably indicating 

isostatic recovery from additional crustal depression beneath 

the De Long Mountains ice cap. The primary lake outlet must 

have been through Howard Pass, whose floor was at about 510 

m asl, because most southern outlets would have been blocked 

by glaciers at this time. Lake deposits in the Howard Pass area 

occur at about 540, 575, and 600 m asl (1775, 1875, and 1975 ft 

asl), reflecting successive positions of local ice dams assigned 

to the Sagavanirktok River glaciation. Because their relation 

to water bodies of Cutler age is unclear, they are designated 

as Sagavanirktok-age deposits (unit sgl) on the map. Farther 

west, a local meltwater drainage channel near present-day Lake 

Kangilipak issues from the outer flank of the Cutler moraine at 

an altitude of about 460 m (1500 ft), and trends south into the 

valley of Aklumayuak Creek. That steep-sided gorgelike valley 

must have been established as a major meltwater conduit from 

the Cutler glacier. Because evidence for widespread high-level 

lake deposits is absent from the map area farther to the west, 

extensive glaciers must have covered most of that part of the De 

Long Mountains and the Noatak River valley during Cutler time.

Diversion of the lower Noatak River from its former 

westward course into the Chukchi Sea may have taken place or 

been completed during Cutler time owing to blockage of that 

route by massive end moraines. The new southward course of 

the Noatak must have been barred at an altitude of at least 90 

m (300 ft) by the transverse bedrock ridge near its present-day 

mouth, because two channel-like troughs appear to have been 

scoured across the rock barrier at that level.

A large proglacial lake may have formed in the Mission Lowland during the deglaciation that followed the Cutler 

advance. Most lake sediments have been eroded or are obscured 

by loess, but their limits are indicated by rare overflow channels, wave-cut notches, beach deposits, and other shoreline 

features.

Late Pleistocene Glaciations

Glacial advances of presumed late Pleistocene age form 

a suite of moraines and related deposits that collectively are 

assigned to the Itkillik glaciation (Hamilton, 1986). The older 

deposits of this assemblage (termed Itkillik I) are beyond the 

range of radiocarbon dating, and therefore are older than about 

40,000 yr. Their age formerly was controversial (Hamilton, 

1994), but recent stratigraphic studies and cosmogenic dating 

show that even the oldest Itkillik-age deposits are younger than 

the last interglacial maximum (younger than about 120,000 yr). 

Deposits of Itkillik I age in the Noatak River valley postdate 

deposition of the last-interglacial Old Crow tephra (Elias and 

others, 1999; Hamilton, 2001), and are correlative with glacial 

deposits in the northeastern Brooks Range and across central 

Alaska that commonly yield cosmogenic ages up to 60-100 

ka (Briner and others, 2005). Younger deposits of Itkillik age 

(termed Itkillik II), radiocarbon-dated between about 24,000 

and 11,000 14C years B.P. (Hamilton, 1986), are correlative 

with moraines assigned to late Wisconsin glaciation elsewhere 

in Alaska that yield cosmogenic ages between about 26 and 11.5 

ka (Briner and others, 2005; Matmon and others, 2006).

Four successively less extensive glacial advances of Itkillik 

age are recognized within the eastern part of the map area, and 

evidence for an additional advance was mapped in upper valleys 

of the De Long Mountains around headwaters of the Nimiuktuk 

River (see table 1). Glacier advances into the eastern and southeastern parts of the Aniuk Lowland and into the trough occupied 

by Etivlik Lake in the extreme northeast corner of the map area 

were in phase with those of the standard central Brooks Range 

glacial succession (Hamilton, 1986, 1994). Glaciers that flowed 

from the west into the Aniuk Lowland formed the Makpik and 

Anisak moraines, which are considered approximately correlative with the two advances of Itkillik I age (units id1A and 

id1B) farther upvalley. The Makpik-Anisak moraine succession 

postdates deposition of the Old Crow tephra (Hamilton, 2001), 

confirming its assignment to the Itkillik glaciation. The very 

localized readvance or stillstand toward the end of Itikillik I 
7

time is labeled as unit id1C (a term new to this map). Younger 

glacial advances issued from source areas in and around the 

head of the Noatak valley; their deposits are assigned to Itkillik 

II glaciation and the late Itkillik readvance (Hamilton, 1986), 

and designated as map units id2 and id3. Comparable drift 

bodies within the De Long Mountains reflect very restricted glacial advances from rugged but isolated highlands and a somewhat more extensive advance down the valley of Avan River.

Contemporaneous glaciation within the Baird Mountains 

was restricted to a few isolated highlands, and consequently is 

discussed separately in a later section.

Glaciations and related events of Itkillik I age

Glacial advances of Itkillik I age in the upper valley of the 

Noatak River formed two closely spaced moraines separated by 

the shallow valley of Atongarak Creek. A comparable double 

moraine encloses Feniak Lake at the north margin of the Aniuk 

Lowland. The outer (unit id1A) moraines at both localities have 

been modified by wave action to altitudes of about 510 m (1675 

ft). Other valley glaciers of Itkillik I age in the eastern part of 

the map area formed end moraines south of Desperation Lake, 

east of Howard Pass, and in southeastern tributaries to the 

Cutler River, but those moraines are not differentiated into 1A

and 1B subunits.

Glacial advances of Itkillik I age that originated in the 

De Long Mountains radiated southward through major valley 

systems. The Makpik and Anisak advances are most clearly differentiated in the central part of the map area, where large compound lateral moraines outline successive ice lobes that flowed 

southeastward out of Nimiuktuk River valley. The outer lobe 

(unit id1A) is traceable into the Makpik moraine; the inner lobe 

(unit id1B) extended into a probable floating ice tongue near the 

mouth of Anisak River and also created the basin now occupied 

by Lake Kangilipak. A younger unnamed recessional moraine 

intersects the Noatak River west of the Anisak River. The Nimiuktuk glacier was fed by a small ice cap near the valley head 

(note highland areas labeled Bg) and by major western tributaries that flowed down the valleys of Seagull and Tumit Creeks 

from sources in the north-central part of the map area.

A smaller western lobe of the Nimiuktuk glacier diverged 

near the mouth of Nimiuktuk valley and flowed southward 

through the narrow bedrock-bounded conduit now occupied 

by the Noatak River. The limit of the older (id1A) advance of 

this lobe is obscured by glaciolacustrine deposits, but morainal 

forms buried beneath those deposits indicate that the glacier 

may have extended down the Noatak to become confluent with 

ice flowing south down the Kaluktavik River drainage system. 

The younger (id1B) advance of the western lobe terminated 

about 6 km above the mouth of Aklumayuak Creek, where it 

formed a heavily eroded end moraine across the constricted 

valley floor.

Glaciers of Itkillik I age farther west formed major southflowing systems that filled the Kugururok and Kaluktavik 

drainages. Patches of drift and expanses of ice-scoured bedrock 

(unit Bg) are exposed locally above the limits of widespread 

glacial-lake deposits. End moraines generally are buried beneath 

blankets of lacustrine sediment, but commonly are evident as 

the subdued arcuate ridges (shown by symbols on the map).

Glacier ice from the Kelly drainage system extended 

into the Mission Lowland, where it may have been confluent 

with glaciers from the Avan and Kugururok valleys. Drift of 

inferred Itkillik 1A age (unit id1A) is traceable along the west 

flank of the Noatak valley at least as far south as the Eli River 

area; a younger end moraine from the three confluent glaciers, 

assigned to the Itkillik 1B advance (unit id1B), seems to parallel 

the Noatak River along the south margin of its floodplain just 

before the river curves into its southward course.

Glacial-lake deposits of Itkillik I age in the Aniuk Lowland 

generally cannot be differentiated from each other, so are shown 

together as map unit igl1. These deposits extend throughout 

the lowland at maximum altitudes that increase progressively 

eastward and northward from about 425 m (1400 ft) asl near 

the Hunt River overflow channel to maximum heights of about 

510 m (1680 ft) asl at the moraine fronts of Itkillik IA age near 

Atongarak Creek and Feniak Lake and in the Howard Pass 

area. Wave-eroded segments of those moraines demonstrate 

that the maximum lake stand was contemporaneous with or 

shortly followed the Itkillik IA glacial advance. Maximum lake 

levels in northern parts of the lowland clearly were controlled 

by the level of Howard Pass (510 m asl), which is significantly 

higher than the head of the Hunt River overflow channel (425 

m asl). Perhaps the lake drained initially southward by way of 

Hunt River, then later northward as the Howard Pass outlet was 

depressed isostatically to a lower position.

Northwest of the Aniuk Lowland, the upper limit of a probably separate Itkillik-age lake in the upper Anisak drainage was 

at about 470 m (1550 ft) asl. Fan-delta deposits were built along 

its former north shore at this level where northern tributaries 

to the Anisak River entered the lake, and the terminus of a 

Sagavanirktok-age moraine was wave-scoured up to a comparable altitude.

Through the central part of the map area, widespread lake 

deposits cover the floors of the four principal southern drainages of the De Long Mountains. Those lake deposits generally 

occur at altitudes lower than the maximum levels of lakes of 

Itkillik I age in the Aniuk Lowland, and they filled the lower 

parts of valleys vacated by glaciers of Anisak (Itkillik IB) age. 

Wave-eroded notches and sparse beach deposits (unit b) along 

the inner flank of the prominent Anisak moraine just east of 

the mouth of Nimiuktuk valley confirm that lake formation 

accompanied or followed glacier retreat there. Because these 

lake deposits probably began to form as glaciers of Anisak age 

receded, they are mapped as unit igl1B to reflect that age.

Within the area vacated by the Nimiuktuk glacier, the 

upper lake limit is at about 370–400 m (1200–1300 ft) asl both 

north and south of the Noatak River (table 2 in Hamilton, 2003). 

That limit remains unchanged westward down the Noatak River 

and through the lower Kaluktavik valley, but farther north up 

the Nimiuktuk and Kaluktavik drainages, the upper lake limit 

increases to 400–410 m (1300–1350 ft) asl, probably reflecting 

glacial isostacy. Because lake deposits along the lower walls of 

these mountain valleys are heavily modified by solifluction and 
8

dissected by erosion, their upper limits are difficult to determine 

in most places. Lake deposits of comparable (Anisak) age and 

appearance are generally absent from the Kuguturok, Avan, 

and Kelly River valleys. This western sector of the De Long 

Mountains may have still been largely ice-covered when the 

lake began to form.

The eastern part of the lake complex must have been 

controlled by an overflow channel at about 400 m (1300 ft) 

asl that extended southward into Aklumayuak Creek from the 

Lake Kangilipak area. Drainage that issued from the valley of 

Aklumayuak Creek then flowed westward down the Noatak 

River valley, initially skirting southern ice margins by way of 

drainage channels along the north flank of the Baird Mountains. 

The western part of the lake complex may have drained through 

a pass at about 350 m (1150 ft) asl at the head of Ahliknak 

Creek, a northern tributary to Eli River. The increased discharge 

through that overflow channel may have triggered construction 

of the enormous fan-delta that extended westward nearly across 

the Mission Lowland from the mouth of the Eli’s bedrock 

valley.

A shallow lake may have existed across much of the Mission Lowland during all or part of Itkillik I time but its extent 

and height are uncertain. Wave-cut notches, wave-abraded 

bedrock, and other shoreline features that appear to be of Itkillik 

I age on the basis of soil, weathering, and morphologic criteria 

(Hamilton, 1986) occur at altitudes of about 120 m (400 ft) near 

the south end of the lowland and rise to 210–230 m (700–750 

ft) asl near its north end. Much of the Eli River fan-delta may 

have formed at this time. Possible overflow channels at 90–130 

m (300–425 ft) across the Igichuk Hills indicate that the lake 

may have been contained behind that bedrock barrier during all 

or part of Itkillik I time.

Either a limited stillstand or readvance of glaciers on and 

around Black Mountain at the head of Nimiuktuk River took 

place near the close of Itkillik I time. Valley glaciers radiated 

southward for short distances into upper Nimiuktuk valley and 

probably also into Seagull Creek and headward parts of Trail 

Creek. In Nimiuktuk River valley, till and outwash assigned to 

this event (units id1C and io1C) were eroded by a glacial lake 

and overlapped by its deposits to an altitude of about 410 m 

(1350 ft), the characteristic upper limit for the lake of Itkillik 

IB age in this part of the map area. The drift must have been 

deposited by a glacial readvance or stillstand during a very late 

phase of Itkillik I glaciation.

Glaciation and related events of Itkillik II age

During Itkillik II time, the moisture necessary to nourish 

glaciers was extremely limited in highlands around the Bering 

Straits owing to glacio-eustatic sea-level depression and consequent subaerial exposure of the broad Bering Platform (Burch, 

1990, p. 45–47; Balascio and others, 2005). Brigham-Grette and 

others (2003) have documented restricted glaciation in easternmost Russia at this time, and only limited glacial advances 

occurred within the De Long and Baird Mountains as well 

(Kaufman and others, 2004).

The most extensive glacier of Itkillik II age was generated 

from highlands in the west-central Brooks Range and flowed 

westward down the upper Noatak and Nigu valleys to terminate below Douglas Creek and west of Etivlik Lake (unit id2). 

Radiocarbon ages from exposures in the Douglas Creek area 

show that this end moraine is of late Wisconsin age (Hamilton 

and others, 1987; Hamilton, 2009). Moraines and outwash from 

this advance show no evidence for interactions with glacial 

lakes in the Aniuk Lowland, but a lake that developed behind 

the moraine as the glacier retreated persisted from about 15,000 

to 9,200 radiocarbon years ago (Hamilton and others, 1987; 

Hamilton, 2009).

At the north margin of the Aniuk Lowland, short valley 

glaciers developed within the Siniktanneyak Mountain block 

during Itkillik II time. Farther west within the De Long Mountains, small glaciers of similar age radiated from Misheguk 

Mountain, Mount Bastille, Amphitheatre Mountain and additional unnamed highlands that stand at 1075–1375 m (3500–

4500 ft) altitude. These glaciers terminated within the mountain 

valleys of Tumit, Okotak, and Trail Creeks, and at the heads of 

Kaluktavik, Kugururok, and Kelly Rivers. Despite the loweraltitude source areas (925–1225 m; 3000–4000 ft asl) flanking 

Avan River valley, numerous cirques generated an unusually 

large valley glacier that flowed south and constructed the Avan 

moraine that intersects and possibly once crossed the Noatak 

valley floor. The Avan valley area must have been subjected 

to much heavier snowfall at this time relative to surrounding 

highlands.

During Itkillik II time, extensive lowlands that remained 

ice-free were inundated by lakes (unit igl2). A narrow lake 

may have extended up the center of the Aniuk Lowland and 

into lower parts of Cutler River valley, but its poorly exposed 

sandy deposits may be largely of slackwater or deltaic origin. 

The upper limit of these deposits rises eastward from about 

300 m (1,000 ft) asl near the mouth of Nimiuktuk valley to 360 

m (1200 ft) asl in the eastern Aniuk Lowland. This increase in 

altitude probably is at least in part the result of isostatic uplift, 

but may also reflect the gradients of slow-flowing rivers.

A glacier-dammed lake occupied the broad valley floor 

near the mouth of Nimiuktuk River (unit igl2). Around its 

shores, wave-eroded notches formed at altitudes of about 300 

m (1000 ft) asl along the lower flanks of moraines of the Itkillik IB drift complex. Deposits of this glacial lake are traceable 

up Nimiuktuk valley and its tributaries, terminating in each 

drainage where the valley floor is above 340 m (1100 ft) asl. 

Farther west, extensive lake deposits that cover lower-lying 

valley floors onlap adjoining lowlands and valley sides to 

about 300–320 m (1000–1050 ft) asl, and the Avan moraine has 

been wave-eroded to a comparable height (320 m). Upper lake 

limits are marked by abrupt contacts between little modified 

lacustrine sediments below and more strongly soliflucted and 

dissected older deposits above. Farther north up the Kugururok, 

Kagvik, and Kaluktavik valleys the lake limit rises to 340–350 

m (1100–1150 ft) asl, probably because of postglacial isostatic 

recovery. An eastern arm of the glacier-dammed lake may have 

extended into the Lake Kangilipak basin, where an abandoned 

channel that heads at 300 m (1000 ft) asl and trends south into 
9

the Aklumayuak drainage may have served as its outlet. Farther 

west, a lower-lying pass at about 280 m (925 ft) asl may have 

allowed drainage from the lake to flow south and then west 

around the Avan glacier during either its advance or an early 

phase of deglaciation.

Evidence for lower lake stands also occurs within the 

Kelly drainage system and across northern parts of the Mission 

Lowland, where shoreline features commonly cluster at about 

210 and 170 m asl (700 and 500 ft, respectively). Although part 

of their height probably is due to isostatic uplift of the northern 

upland, the ultimate cause of these lake stands is uncertain. No 

significant barrier of Itkillik II age is recognized in or below the 

Mission Lowland.

Parts of the map area that were unglaciated during Itkillik II time were subjected to intense periglacial activity. Some 

of these surfaces were consistently above lake level, but others 

must have been exposed subaerially as the lake repeatedly burst 

out through its ice dam and then refilled. These nonglaciated 

areas exhibit extensive solifluction slopes that are inactive or 

weakly active today. Where surface or near-surface bedrock is 

present, stabilized frost-shattered rubble represents formerly 

active felsenmeer (Washburn, 1980, p. 219–223) on upland 

surfaces, and stabilized sheets or aprons of talus rubble are 

widely present on slopes. The weathered and lichen-covered 

surfaces of some bedrock blocks that were partly detached from 

their outcrops demonstrate that displacement by frost wedging 

has ceased. These inactive periglacial features provide a useful 

guide to the limits of Itkillik II-age glaciation.

Glaciation in the Baird Mountains

Only a few small glaciers of middle(?) to late Pleistocene 

age were generated within the Baird Mountains west of the 

Cutler River drainage. The advances of those glaciers were 

marked by moraines (units id and id1) and outwash near valley 

heads and by adjoining freshly ice-scoured surfaces. The most 

extensive advance, about eight kilometers in length, issued 

from a cirque in rugged but unnamed highlands at the head of 

Akikukchiak Creek. Outwash that spilled eastward from this 

advance formed a local terrace (unit tg) in an adjoining valley, 

which also has a small morainal deposit at its head. Two short 

glaciers about 3-4 km in length developed from cirques on the 

north face of Mt. Angayukaqsraq near the south-central margin 

of the map.

Other valley-head glacial deposits (unit d) lack morainal 

ridges and surface erratics but form arcuate bodies bordered by 

former ice-marginal channels. These features could be of either 

late or middle Pleistocene age. They outline a north-flowing 

glacier that extended about 4 km from a cirque on Tutatalak 

Mountain to the valley of Akikukchiak Creek. Similar subdued 

glacial deposits (unit d?) associated with abraded and channeled 

bedrock (unit Bg) occur a few kilometers beyond the limits of 

Itkillik-age drift in the two other localities described above.

The Pleistocene-Holocene Transition 

and Subsequent Holocene Events

A final readvance of alpine glaciers in the central Brooks 

Range generated end moraines and ice-stagnation deposits (unit 

id3) around Etivlik Lake in the northeast corner of the map 

area. Radiocarbon dates from localities elsewhere in the central 

Brooks Range show that this readvance took place between 

about 12,800 and 11,500 14C yr B.P. (Hamilton, 1986, 1994). 

Surprisingly, no evidence for this readvance seems to be present 

within the upper Noatak River valley.

In the De Long Mountains, end moraines were deposited 

at about this time near the mouth of a cirque-headed tributary 

valley at the north flank of Misheguk Mountain and in several 

mountain valleys between headward parts of Trail and Tumit 

Creeks and near the heads of Avan and Kelly Rivers. Patches 

of drift (units d and d?) on the floors of these and neighboring 

steep mountain valleys may also date from the same interval.

Because of the high seasonal discharge of the Noatak River 

(Childers and Kernodle, 1981), incision through lake deposits of 

Itkillik age probably was rapid. However, as the river continued downcutting, it would have been superimposed on bedrock 

and moraines along parts of its course. Downcutting would 

have been impeded for some time at those levels until it could 

incise the barriers, resulting in terrace formation. Because of the 

map’s small scale, every individual river terrace segment that 

was formed during downcutting cannot be shown. Therefore, I 

have combined those terrace remnants into a maximum of four 

general terrace levels (tg1, tg2, tg3, and tg4).

Through the Aniuk Lowland, late-glacial river downcutting 

began by about 13,600 14C yr B.P. at levels perhaps 30 m above 

the present-day river (Hamilton, 2001). Radiocarbon-dated terrace remnants about 15 m above the present river level indicate 

that the Noatak may have flowed at that lower level for an undetermined interval about 10,000 yr B.P. Terrace remnants through 

the Aniuk Lowland generally are too small to show on the map. 

Farther west, the highest consistent terrace level (tg1) is 

recognized along the entire stretch of the Noatak River from the 

mouth of Nimiuktuk River westward to the Kelly River area. 

This terrace commonly stands about 50 m above modern river 

level, but it ranges between about 40 and 60 m high along some 

sectors of the river (Hamilton, 2003, table 3). The terrace must 

have formed when stagnant glacier ice was still present on the 

valley floor, because at several localities (the mouth of Nimiuktuk River is a good example) its surface bears kettle lakes and 

kettle depressions. The Noatak River may have reoccupied this 

level several times as breaching of the ice dam near Avan River 

caused outburst floods that drained the lake.

Terraces at about 25–35 m above modern river level (tg2) 

occur most consistently along the Noatak River from just above 

Aklumayuak Creek to the Kugururok River confluence. These 

terraces also extend for short distances along the lower courses 

of Kugururok and Kaluktavik Rivers. Unit tg2 is principally 

associated with end-moraine complexes of Itkillik IB age, indicating that massive boulder-rich deposits across the valley floor 

must have retarded river downcutting at those places. Terrace 
10

remnants at comparable heights above river level occur sparsely 

in the Aniuk Lowland and elsewhere along the river, but they 

generally are too small to map. Two radiocarbon ages of about 

13,300 14C yr B.P. were obtained from a 25-m terrace near the 

mouth of Aklumayuak Creek (Hamilton, 2009), and a somewhat higher (35 m) bluff a short distance downvalley yielded 

a similar age of about 13,150 yr B.P. These ages, and a slightly 

older radiocarbon determination from the Aniuk Lowland 

(Hamilton, 2001, 2009) indicate that the Noatak River must have 

been downcutting through the interval about 35–25 m above its 

modern level at about 13,600–13,000 14C yr B.P. Radiocarbon 

ages representing this time span are relatively common within 

the central Brooks Range (Hamilton, 1986), and evidently mark 

a time of widespread recolonization by shrubs and peat-forming 

plants under conditions of increasing temperature and moisture 

(Bigelow and Powers, 2001). Perhaps vegetation was able to 

stabilize the river’s floodplain sufficiently at this time to permit 

better preservation of alluvial terrace remnants.

Terraces at about 15 m above river level (tg3) are widespread along segments of the Noatak River in the Aniuk Lowland and, farther downriver, below Aklumayuak Creek, and in 

the stretch between Kugururok and Kelly Rivers. Just above 

the mouth of Kelly River, bluff deposits standing 20 m above 

river level represent a terrace of probably comparable or slightly 

greater age. Thaw-lake deposits and basal peats in thaw depressions near the crest of that bluff yielded radiocarbon ages of 

about 9,200 and 9,400 14C yr B.P. (Hamilton, 2009). The thaw 

lakes and depressions, which formed under higher summer 

temperatures of the early Holocene warm interval (Bigelow 

and Powers, 2001), do not provide a direct date on river height, 

but they do provide a minimum limiting age on river downcutting from that level. They differ only slightly in age from the 

10,000-year-old 15-m terrace remnant in the Aniuk Lowland 

(Hamilton, 2009).

An extensive lower terrace (tg4) stands at about 8–10 m 

above river level. This feature is recognized around the mouths 

of Cottonwood Creek and Nimiuktuk and Kelly Rivers, and also 

along the stretch of the Noatak River between the Cottonwood 

Creek and Kelly River confluences. Unit tg4 is also mapped 

along Kugururok River opposite Lake Kaiyak. Although alluvial 

surfaces at this level have been preserved elsewhere, they are 

too small to map separately or are indistinguishable from older 

floodplain deposits (unit al1).

In the Mission Lowland, terrace deposits are rare and 

most are only a few meters above river level. Terraces are inset 

within fan-delta sediments along Eli River and near the mouth of 

Agashashok River, suggesting that fan-delta formation may have 

ceased by the close of the Pleistocene or shortly thereafter.

Because of its low altitude and position close to the mouth 

of the Noatak River, the Mission Lowland probably responded 

to eustatic sea-level rise during the Holocene. Flooding of the 

Bering Platform would have caused base level for the river 

to rise significantly, impeding its discharge and causing it to 

aggrade its silt-rich suspended load across the Mission Lowland 

floor. Strong upvalley winds would have entrained silt from the 

aggrading river system, and perhaps also from the beds of former 

Pleistocene lakes. Much of this silt was laid down as a thick 

blanket of loess across northern parts of the lowland. Because 

of Holocene alluviation, bluff exposures are absent from the 

Mission Lowland; and thick blankets of eolian and alluvial silt 

ensure that surface exposures of Pleistocene-age deposits are 

rare.

Glacial deposits of late Holocene (Neoglacial) age are 

common in cirques through the central Brooks Range (Ellis and 

Calkin, 1984), where they generally are limited to locations close 

to the termini of present-day glaciers. Modern glaciers within the 

Noatak National Preserve occur only near the head of Imelyak 

River (near the map’s southeast margin), where two very small 

cirque glaciers are present. Consequently, drift of Neoglacial age 

is rare in the map area. Very small deposits (unit nd) are associated with the two modern glaciers, and several drift deposits that 

may be of comparable age occur within the De Long Mountains 

at the bases of steep north-facing cirque headwalls between 

headward parts of Trail and Tumit Creeks and in highlands along 

the east flank of Avan River valley.

Following deglaciation of cirques and upper valley heads, 

talus rubble began forming on lower parts of cirque and valley 

walls that were oversteepened by glacial erosion. Within upper 

valleys glaciated during Itkillik II time, active talus accumulations are so numerous and closely spaced that they are shown 

as symbols rather than named depositional units. Older talus 

accumulations that have become stabilized, weathered, and 

lichen-covered (unit tri

) are more characteristic of cirques and 

valley heads that were not glaciated during Itkillik II time, and 

therefore they may serve as useful relative-age indicators.

Acknowledgments

This map integrates recent field studies with previous mapping that, in easternmost parts of the map area, dates back as 

far as 1978. At least eight helicopter-supported field operations 

and five traverses down the Noatak River spanned the succeeding years up to 2005, and each of those projects had its own 

colleagues, field assistants, and helicopter and (or) fixed-wing 

aircraft pilots. I truly regret that I cannot thank each of these 

individuals separately and acknowledge their often unique contributions. Full support for geologic studies through the eastern 

part of the map area was furnished initially by the U.S. Geological Survey (USGS), and partial support continued subsequently 

through its Emeritus program. Later stages of the project that 

encompassed the western half of the map area were supported 

by the U.S. National Park Service (NPS), initially through the 

efforts of Robert Gal. The final (2005) season of field mapping and subsequent preparation of this map and accompanying report was directed by Bruce A. Giffen, with funding by 

the NPS through its Geologic Resources Evaluation Program. 

The digital map files for the eastern part of the Noatak National 

Preserve (NNP) were created under NPS contract to Earth 

Satellite corporation (Rockville, MD); those for the western part 

of the NNP were constructed by GIS personnel of the USGS. 

Keith Labay, in particular, provided patient and expert editorial 

assistance, including input on color schemes, electronic symbols, 

and layout. Thanks also to Bruce Giffen, John P. Galloway, and 

Robert B. Blodgett for their constructive and thorough reviews 

of the map and report.
11

DESCRIPTION OF MAP UNITS

SURFICIAL DEPOSITS 

[Map units shown in parentheses, such as (id), indicate thin and generally discontinuous deposits over 

near-surface bedrock. Map units shown with slashes, such as us/d, indicate deposits of the first unit above 

known or inferred subsurface deposits of the second unit (color represents upper unit). Units of either type 

are described below only where additional explanation is necessary. Units queried where uncertain]

FAN DEPOSITS

af Steep alpine fan deposits (Holocene to late Pleistocene)—Coarse, very poorly sorted, subangular to subrounded silty sandy gravel at mouths of avalanche chutes and steep canyons. Upper 

segment generally channeled, with levees of angular to subangular coarse debris. Subject to 

snow avalanches during winter, slushflows during spring snowmelt, and debris flows during 

summer. Surface gradients generally 12° to 25°, intermediate between gradients of alluvial 

fans and talus cones

afi Inactive alpine fan deposits (late Pleistocene)—As described in unit af. Generally weathered 

and covered with sod and vegetation. Some are periglacial relics that formed beyond limits 

of ice advances of last major (Itkillik II) glaciation

f Fan deposits (Holocene to late Pleistocene)—Range from poorly sorted, weakly stratified, 

subangular, silty, sandy coarse gravel at mouths of steep canyons to moderately sorted and 

stratified subrounded sandy fine gravel at mouths of large tributary valleys with relatively 

gentle gradients. Locally subject to icings (aufeis) during winter

fa Active fan deposits (Holocene)—As described in unit f. Differentiated only on large compound fans to distinguish active from inactive fan elements

fi Inactive fan deposits (Holocene to late Pleistocene)—As described in unit f. Generally 

weathered and covered with sod and vegetation

fd Fan-delta deposits (late Pleistocene)—Alluvial-fan deposits, as described in unit f. Grade 

downslope into deltaic and lacustrine facies (well sorted and generally well stratified sand, 

silt, and fine gravel). Commonly associated with glaciolacustrine deposits

fd2 Fan-delta deposits, younger component (late Pleistocene)—Alluvial-fan and delta deposits, as 

described in unit fd. Form younger element of large, smooth-surfaced, low-gradient deposit 

south of Eli River beyond mouth of its bedrock valley

fd1 Fan-delta deposits, older component (late Pleistocene)—Alluvial-fan and delta deposits, as 

described in units fd and fd2. Form eroded remnants around unit fd2. Surfaces are higher 

and more deeply dissected by streams than unit fd2

ALLUVIUM

al Alluvium, undivided (Holocene)—Varies from moderately sorted, subangular to subrounded, 

stratified, coarse gravel in upper valleys to muddy, fine gravel and gravelly mud along slowflowing stretches of major streams. Along smaller streams, unit includes fan, floodplain, and 

low terrace deposits that are too small to be designated separately

al2 Modern alluvium (Holocene)—Gravel to gravelly mud, as described in unit al. Generally 

unvegetated and subject to annual flooding. Commonly subject to aufeis formation. Differentiated only along principal streams

al1 Low alluvial-terrace deposits (Holocene)—Gravel to gravelly mud, as described in unit al. 

Mantled with 0.3–1 m of silt, sand, turf, and peat, and generally vegetated. Form terraces 

generally within 3–4 m of modern stream levels. Differentiated only along principal streams

alsa Alluvium, sand facies (Holocene to late Pleistocene)—Moderately sorted to well-sorted, fine 

to medium sand, parallel bedded to slightly crossbedded, commonly with thin interbeds of 

sandy peat or organic silty fine sand. Deposited initially by slow-flowing streams within 

basins partly dammed by end moraines in valleys of Noatak and Cutler Rivers and Amakomanak Creek. Upper 1–2 m locally reworked by wind into sand sheets and dunes. Commonly 

grades downward into lacustrine deposits 
12

als Alluvium, silt facies (Holocene)—Moderately sorted to well-sorted silt, parallel bedded to crossbedded, commonly with interbeds of organic silt and peat. Forms channel and floodplain of 

small sluggish stream that crosses glacial-lake deposits south of Eli River fan-delta

gr Gravel deposits, undifferentiated (late Pleistocene)—Gravel and sandy gravel of diverse origins and composition. Generally applies to isolated, gravelly erosion remnants of uncertain 

composition and origin. Deposits along Noatak valley floor typically are lag concentrates 

formed from glacial deposits by wave erosion

grfn	 Gravel deposits, fine-grained (Holocene to late Pleistocene)—Subrounded small pebbles, with 

some platy stones up to large pebble size. Mapped in southwest part of map area north of 

Agashashok River mouth, where deposits may represent remnants of fan or fan delta of Agashashok River, reworked by wave action along former lake margin. Also present near outer 

flank of Cutler moraine west of Cutler River mouth

TERRACE DEPOSITS

tg Terrace gravel, undivided (late to middle Pleistocene)—Alluvial gravel and sandy gravel, 

commonly capped by flood-plain deposits of silt, sand, or peat up to 1–2 m thick. May 

locally have thicker mantle of eolian silt or thaw-lake deposits

tg4 Terrace gravel, lowest-level (Holocene)—Alluvial gravel, as described in unit tg. Forms broad 

alluvial surfaces 8–12 m above river level along Noatak River and lower courses of several 

triburaties. Thaw lakes common

tg3 Terrace gravel, low-level (Holocene)—Alluvial gravel, as described in unit tg. Silt and peat 

cover thicker than on unit tg4. Forms terrace surfaces about 15 m above Noatak River and 

lower Kaluktavik and Kelly Rivers. Thaw lakes common

tg2 Terrace gravel, intermediate-level (late Pleistocene)—Alluvial gravel, as described in unit 

tg. Silt and muskeg cover thicker than on unit tg3. Forms terrace surfaces 25–35 m above 

Noatak River and lower courses of some tributaries. Some kettle lakes present

tg1 Terrace gravel, highest-level (late Pleistocene)—Alluvial gravel, as described in unit tg. Generally bears thick (up to 3–5m?) silt and muskeg cap. Forms terrace surfaces about 50 m above 

Noatak River. Kettle lakes common

COLLUVIAL DEPOSITS

c Colluvium, undivided (Holocene to middle Pleistocene)—Mixed solifluction deposits (unit s) 

and talus-rubble deposits (unit tr) in sheets and aprons more than about 0.5 m thick. Most 

extensive on moderate to steep slopes above and beyond limits of ice advances of Itkillik 

age. Also common on upper slopes below exposed or near-surface bedrock

cm	 Colluvium-filled mountain valley (Holocene to middle Pleistocene)—Colluvial deposits mixed 

with alluvium. Mapped in narrow mountain valleys, where individual deposits are too small 

to be designated separately. Talus predominates on steep upper slopes; solifluction, fan, and 

debris-fan deposits predominate on lower slopes. These colluvial deposits interfinger with 

alluvium toward valley center. Generally restricted to valleys that were not glaciated during 

Itkillik (late Pleistocene) time

s	 Solifluction deposits (Holocene to late Pleistocene)—Very poorly sorted, unstratified to weakly 

stratified, stony silt and organic silt; forms smoothly graded, gently to moderately sloping 

sheets and aprons more than 0.5 m thick. Platy to elongate stones generally oriented parallel 

to slope. Most common beyond outer limits of Itkillik-age drift; locally present on deposits 

of Itkillik I age

av Avalanche tracks and deposits (Holocene)—Angular unsorted unstratified loose rock rubble, 

commonly with intermixed woody plant debris. Form tongues and fans along lower walls of 

mountain valleys. Associated with tracks and chutes where soil and vegetation are generally 

absent and that commonly are bordered by zones of damaged trees or shrubs. Recognized 

only in deep mountain valleys near southeast margin of map area

pr Protalus rampart deposits (Holocene)—Unsorted, unstratified, coarse angular rock debris forming arcuate low ridges. Associated with persistent snowbanks in shaded sites, commonly at 

bases of cirque headwalls. Subject to rockfalls during spring thaw
13

rg Rock-glacier deposits, undifferentiated (Holocene to late Pleistocene)—Coarse angular rock 

debris, as described in unit rga. Active and inactive components either undetermined or too 

small to be mapped separately

rga Rock-glacier deposits, active (Holocene)—Very poorly sorted, unstratified, coarse angular rock 

debris with matrix of silt and fine rubble; contains abundant interstitial ice. Upper surfaces 

generally unvegetated, unweathered to moderately weathered; lichen cover sparse. Frontal 

slopes barren, steep (35°–38°), and highly unstable; they meet upper surfaces at abrupt angle. 

Subject to slow downslope motion. Fed by talus cones and aprons, which commonly are too 

small to show on map. Form lobate deposits along bases of valley walls and tongue-shaped 

deposits within cirques. Tongue-shaped deposits commonly overlie stagnant glacier ice

rgi Rock-glacier deposits, inactive (Holocene to late Pleistocene)—Coarse angular rock debris, 

as described for unit rga, but lacking interstitial ice. Upper surfaces and frontal slopes 

weathered, covered by lichens, and commonly partly covered by sod and vegetation. Frontal 

slopes grade into upper surfaces without abrupt angles

tr Talus rubble (Holocene to late Pleistocene)—Angular, unsorted rock debris, as described in 

unit tra. Active and inactive components either undetermined or too small to be mapped 

separately

tra Talus rubble, active (Holocene)—Angular, unsorted, unstratified rock debris forming cones 

and aprons more than 2 m thick and generally sloping 30°–33° along lower flanks of mountain valleys and on cirque headwalls. Also forms thinner and generally discontinuous sheets 

over many uplands mapped as bedrock. Generally unvegetated, unweathered to slightly 

weathered; lichen cover sparse to absent. Subject to rockfalls from slopes above, especially 

during spring thaw

tri Talus rubble, inactive (Holocene to late Pleistocene)—Angular rock debris, as described in 

unit tra. Generally weathered and lichen covered, and with partial sod cover at some localities. Thin (less than 1–2 m) blankets of stabilized talus occur on many uplands mapped as 

undifferentiated bedrock

ls Landslide deposits (Holocene to late Pleistocene)—Unsorted, unstratified, coarse to fine, angular rubble, commonly with matrix of finer debris; form lobes below detachment scars and 

slide tracks on steep rock walls. Subject to rapid downslope movement and long periods of 

relative stability. Most common in upper mountain valleys near north and south margins of 

map area

fl Flow deposits (Holocene to late Pleistocene)—Very poorly sorted stones in abundant muddy 

matrix. Generally originate in slumps and terminate as lobes. Mapped primarily on Noatak 

valley floor between Avan and Kelly Rivers. Many smaller flows occur in glaciolacustrine 

deposits exposed along Noatak River and its principal tributaries, but these generally are too 

small to constitute mappable units

SAND, SILT, AND ORGANIC DEPOSITS

sa Sand deposits (late Pleistocene)—Moderately sorted, fine to medium sand, horizontally bedded 

to slightly crossbedded, commonly with thin interbeds of sandy peat or organic silty fine 

sand. Form terraces up to 25 m high within basins partly dammed behind end moraines in 

upper Noatak and Nigu River valleys

si Ice-rich silt deposits (Holocene to late Pleistocene)—Silt deposits, more than 1–2 m thick in 

swales and other depressions; commonly with ice-wedge polygon networks. Mapped primarily along lower course of Noatak River below Eli River

us Upland silt deposits (Holocene to early Pleistocene)—Poorly sorted to moderately sorted, 

generally unstratified, silt, organic silt, and slightly stony silt draped over uplands of low to 

moderate relief. Formed from windblown silt (loess) that was mixed by frost action with local 

organic matter and weathering products. Generally has tussock cover broken by frost boils. 

Commonly grade downslope into thick, massive, organic-rich silt or into solifluction deposits

m Muskeg (Holocene to middle Pleistocene)—Peat, organic silt, and organic detritus more than 

1–2 m thick in areas of restricted drainage where water table is at or close to surface. 

Mapped only along passes to Squirrel River in extreme southwest corner of map area
14

LACUSTRINE, GLACIOLACUSTRINE, AND GLACIAL-MARINE DEPOSITS

General

b Beach deposits (Holocene)—Moderately well sorted, coarse to medium sand, commonly mixed 

or interbedded with platy fine gravel. Locally forms ridges of poorly sorted, gravelly sand 

to sandy coarse gravel where mixed by ice shove. Small deposits occur locally around most 

lakes, but deposits of mappable size occur around Lake Narvakrak and along east shore of 

Feniak Lake. Older deposits (late Pleistocene unit mapped as b?) occur at margins of glacial 

lakes along lower course of Noatak River and locally farther upvalley

dt Deltaic deposits (Holocene to late Pleistocene)—Generally well stratified sand, gravelly sand, 

and sandy fine gravel; deposited by streams at lake margins. Commonly build outward into 

lake, and overlie fine-grained lacustrine deposits. Mapped only at north ends of Feniak and 

Desperation Lakes and at southwest corner of Lake Kangilipak

dts Silty deltaic deposits (Holocene)—Deltaic deposits, as described in unit dt; predominantly 

silt. Some sand present, but larger clasts almost entirely absent. Mapped only at Noatak 

River mouth in extreme southwest corner of map area

l Lacustrine deposits (Holocene to late Pleistocene)—Clayey silt, silt, and sand, commonly well 

stratified; grade into sand and gravelly sand near former shorelines and sandy fine gravel 

near former river mouths. Commonly include beach deposits too small to be designated 

separately. Mapped primarily along receding lake margins or beds of lakes that have recently 

drained

tl Thaw-lake deposits (Holocene)—Weakly stratified to nonstratified silt, organic silt, and clayey 

to sandy silt; generally contain abundant ice as lenses, wedges, and interstitial grains. 

Occupy thaw basins in glacial-lake deposits on valley and lowland floors

Within Brooks Range

igl Glacial-lake deposits of Itkillik age (late Pleistocene)—Stony silt to stony silty clay, with 

some silty fine sand, massive to faintly bedded. Contain sparse to abundant subangular to 

subrounded pebbles, cobbles, and small boulders that commonly are striated. Grade into 

gravelly sand to sandy fine gravel near former stream mouths. Mapped as compound unit 

(for example igl/B, igl/id, igl/io) where deposit drapes or overlies bedrock, drift, outwash, 

or other glacial deposits. Arcuate map symbols designate end moraines of preceding glacial 

advances that later were draped by lake deposits. Upper limits locally marked by wave-cut 

scarps, wave-scoured bedrock, and beach deposits 

igl2 Glacial-lake deposits of Avan (Itkillik Phase II) age (late Pleistocene)—Glacial-lake deposits, 

as described in unit igl. Associated with moraine dam at mouth of Avan River. Upper limits 

generally well defined. Form extensive deposits on floors of Kelly, Kugururok, and Kaluktavik River valleys and narrow belt incised within older glacial-lake deposits along Noatak 

valley floor through Aniuk Lowland

igl1 Glacial-lake deposits of Itkillik Phase I age (late Pleistocene)—Glacial-lake deposits, as 

described in unit igl. Upper limits commonly obscured by solifluction. Widespread across 

floor of upper Noatak basin (Aniuk Lowland) up to altitudes that rise progressively eastward 

from about 425 m (1400 ft) to 510 m (1680 ft) asl

igl1B Glacial-lake deposits of Anisak (Itkillik Phase IB) age (late Pleistocene)—Glacial-lake 

deposits, as described in unit igl, that formed within southern valleys of De Long Mountains 

during ice recession from Anisak moraine. Associated with erosional scarps along inner 

flanks of Anisak moraine. Upper limits elsewhere commonly obscured by solifluction. Filled 

Kaluktavik, Kugururok, and Kelly River valleys during or following their deglaciation; 

locally present up to 425 m (1400 ft) asl in upper parts of those drainages

igl1A Glacial-lake deposits of Makpik (Itkillik Phase IA) age (late Pleistocene)—Glacial-lake 

deposits, as described in unit igl, that formed during early phase of Itkillik glaciation. 

Locally present up to 500 m (1650 ft) asl between Feniak and Desperation Lakes 

sgl Glacial-lake deposits of Sagavanirktok River age (middle Pleistocene)—Glacial-lake deposits, as described in unit igl. Confined by moraines of Sagavanirktok River age near Feniak 

Lake and in Howard Pass area

idt Deltaic deposits of Itkillik age (late Pleistocene)—Generally well stratified sand and sandy fine 

gravel, as described in unit dt. Formed near mouths of streams that flowed into glacial lakes of 

Itkillik age; typically overlie and interfinger with fine-grained deposits of those glacial lakes
15

sdt Deltaic deposits of Sagavanirktok River age (middle Pleistocene)—Deltaic deposits, as 

described in units dt and idt. Mapped along north side of Anisak River valley between Picnic 

and Setting Sun Creeks. Also occur as flat-topped deposit 15 m high on south side of Flora 

Creek at distal end of outwash terrace of Sagavanirktok River age. On south side of Howard 

Pass, composite unit igl/sdt is probable deltaic deposit that is covered by thin glaciolacustrine sediments 

cgl Glacial-lake deposits of Cutler age (middle Pleistocene)—Glacial-lake deposits, as described 

in unit igl. Formed beyond Cutler moraine and preserved above limits of unit igl1 in Cutler 

and Anisak River valleys. Surfaces commonly dissected by stream networks. Mapped as 

composite unit cgl/sd where lacustrine deposits overlap end moraines of Sagavanirktok 

River age

Mission Lowland

ml Lacustrine and other fine-grained deposits (Holocene to late Pleistocene)—Silt, ice-rich silt, 

and sandy silt, with some sand and sandy fine gravel. Formed in part by lacustrine processes 

and in part by slow-moving floodwaters retarded by narrow outlet (Igichuk Hills) near 

mouth of Noatak River. Generally concealed beneath thick loess cover

ml2 Younger lacustrine and other fine-grained deposits (Holocene to late Pleistocene)—Finegrained sediments, as described in unit ml; broadly distributed across Noatak valley floor. 

Maximum altitudes rise northward from about 15 m (50 ft) near Agashashok River mouth to 

140 m (450 ft) near mouth of Kelly River. May have formed largely by alluviation of Noatak 

River in response to Holocene sea-level rise

ml1 Older lacustrine and other fine-grained deposits (late Pleistocene)—Fine-grained sediments, 

as described in unit ml. Extend beyond limits of unit ml2 up to various altitudes as high as 

260 m (850 ft) asl. Commonly associated with lake-margin features such as overflow drainage channels and other shoreline features

si/cgm Glacial-marine deposits of Cutler(?) age (middle Pleistocene)—Pebbles, cobbles, and small 

boulders, commonly striated; in gray silty matrix. Exposed only in coastal bluffs along north 

shore of Kotzebue Sound. Overlain by 7–10 m of ice-rich silt that may be eolian in origin; 

therefore is designated as composite unit

GLACIAL DRIFT AND ICE-CONTACT GRAVEL

d Drift, undifferentiated (late to early Pleistocene)—Glacial deposits, as described in unit id, of 

uncertain age

Late Holocene glaciation (Neoglaciation)

nd Drift of neoglacial age (Holocene)—Unsorted unstratified angular rubble; forms lobes and 

arcuate ridges with steep and commonly unstable slopes. Clasts unweathered to slightly 

weathered; generally unvegetated except by lichens. Restricted to cirques at higher altitudes, 

commonly near valley heads

nd2 Drift of late neoglacial age (Holocene)—Angular rubble, as described in unit nd; forms lobes 

and arcuate ridges of ice-cored drift with steep, unstable frontal slopes. Unvegetated, 

unweathered to slightly weathered, and with lichens sparse to absent. Restricted to cirques, 

and generally associated with active glaciers

nd1 Drift of early neoglacial age (Holocene)—Angular rubble, as described in unit nd. Forms more 

subdued lobes and ridges with stable frontal slopes; generally eroded by axial streams. 

Weathered and lichen encrusted, with partial sod cover in some localities

Itkillik glaciation

id Drift of Itkillik age, undifferentiated (late Pleistocene)—Unsorted to poorly sorted, generally unstratified, compact till; ranges in composition from muddy sandy gravel to gravelly 

muddy sand, with local stratified ice-contact deposits as described in subunit ik3. Contains 

faceted and striated stones up to large boulder size

id3 Drift of late Avan (late Itkillik Phase II) readvance (late Pleistocene)—Glacial deposits, as 

described in unit id, with irregular morphology and narrow-crested moraines. Loess cover 
16

generally absent, and exposed stones very slightly weathered. Oxidation has penetrated 

only 20–30 cm into well-drained deposits. Most extensive around Etivlik Lake and on Nigu 

valley floor in northeast corner of map area. Locally present in higher valley heads within 

De Long Mountains

ik3 Kame and kame-terrace deposits (late Pleistocene)—Thick and extensive deposits of moderately sorted sand and sandy gravel; upper surfaces level to sharply conical and well drained, 

and generally with steep ice-contact flanks. Associated with stagnating glaciers of late Itkillik Phase II age in Etivlik Lake-Nigu valley area

id2 Drift of Avan (Itkillik Phase II) age (late Pleistocene)—Glacial deposits, as described in unit 

id. Form sharply defined arcuate drift belts with narrow-crested (generally 1–3 m) moraines, 

prominent knob and kettle morphology, and conspicuously channeled outwash trains. Loess 

and solifluction cover generally lacking on crests and upper slopes. Exposed boulders are 

slightly to moderately weathered; oxidation has penetrated 40–50 cm into well-drained 

deposits. Most swales have no solifluction deposits, and abandoned meltwater channels 

commonly are floored with thin sod mats above coarse gravel. Overlapped by glacial-lake 

deposits to about 180 m (600 ft) altitude, and wave-eroded to altitudes locally as great as 

320 m (1060 ft) in western part of map area

ik2 Kame and kame-terrace deposits (late Pleistocene)—Thick and extensive deposits of sand and 

gravel, as described in unit ik3. Most extensive within drift of Itkillik Phase II age on floor 

of upper Noatak valley near east margin of map area

id1 Drift of Itkillik Phase I age, undivided (late Pleistocene)—Glacial deposits, as described in 

unit id. Moraine crests generally 5–10 m wide and partly bare of loess; upper slopes blanketed by stony organic silt (loess and colluvium) 0.5–2 m thick; swales filled with deposits 

of ice-rich organic silt 2–5 m thick. Morphology locally more subdued where overlapped by 

glaciolacustrine deposits. Forms extensive hummocky drift bodies beyond limits of Itkillik Phase II drift. Shown in parentheses (id1) where drift is thin and patchy, and also where 

drift of Itkillik Phase I age has been mixed with silt, rock rubble, and organic detritus on hill 

slopes or lower valley walls to become a compound (glacial + colluvial) deposit

ik1 Kame and kame-terrace deposits (late Pleistocene)—Unusually extensive and thick deposits 

of water-washed sand and gravel deposits, as described in unit ik3, deposited within drift of 

Itkillik I age

id1C Drift of late Anisak (Itkillik Phase IC) age (late Pleistocene)—Glacial deposits, as described 

in unit id. Formed by late stillstand or readvance of residual glaciers near head of Nimiuktuk 

River valley and within upper valley of Seagull Creek

id1B Drift of Anisak (Itkillik Phase IB) age (late Pleistocene)—Glacial deposits, as described in 

unit id. Form separate inner moraines within drift complexes of Itkillik Phase I age. Includes 

Anisak moraine, a prominent end moraine at mouth of Anisak River, and drift on floor of 

upper Noatak valley above Atongarak Creek. Overlapped by glacial-lake deposits to altitudes of about 400 m (1300 ft)

id1A Drift of Makpik (Itkillik Phase IA) age (late Pleistocene)—Glacial deposits, as described in 

unit id. Form separate outer moraines within drift complexes of Itkillik Phase I age. Includes 

Makpik moraine, near mouth of Makpik Creek, and moraine complex in upper Noatak 

valley just below Atongarak Creek

ik1A Kame and kame-terrace deposits (late Pleistocene)—Unusually thick and extensive deposits 

of water-washed sand and gravel, as described in unit ik3, deposited within drift of Itkillik 

Phase 1A age

i-c Ice-contact meltwater deposits (late Pleistocene)—Meltwater-washed sand and gravel, as 

described in unit ik3. Commonly associated with finer grained glaciolacustrine deposits. 

Probably formed by accelerated melting of debris-covered stagnant glacier ice where in 

contact with transgressing glacial lake. Most common on lateral and end moraines of Anisak 

(unit id1B) advance on Noatak valley floor between Anisak and Nimiuktuk Rivers

Sagavanirktok River glaciation

sd Drift of Sagavanirktok River age (middle Pleistocene)—Poorly sorted nonstratified till; probably ranges in composition from silty sandy bouldery gravel to clayey stony silt, with local 

deposits of moderately well sorted and stratified gravel. Moraines relatively subdued and 

generally discontinuous. Generally covered by thick (>3 m) blanket of silt, stony silt, and 
17

organic silt (loess, solifluction, and marsh deposits), but crests of some ridges and knolls 

yield limited exposures of weathered gravel and erratic boulders of resistant lithologies. 

Designated only in eastern part of map area

sk Kame and kame-terrace deposits (middle Pleistocene)—Unusually thick and extensive 

deposits of water-washed sand and gravel, as described in subunit ik3, deposited against drift 

of Sagavanirktok River age. Mapped only north of Aniuk River 22 km southwest of Howard 

Pass

sd2 Drift of late Sagavanirktok River age (middle Pleistocene)—Till and stratified ice-contact 

deposits, as described in unit sd. Forms inner moraine belts within drift complexes in eastern part of map area

sd1 Drift of early Sagavanirktok River age (middle Pleistocene)—Till and stratified ice-contact 

deposits, as described in unit sd. Forms outer moraine belts within drift complexes in 

eastern part of map area. Generally more dissected and more subdued by mass wastage than 

deposits of unit sd2

Cutler glaciation

cd Drift of Cutler age (middle to early Pleistocene)—Till and stratified ice-contact deposits, as 

described in unit sd. Formed by east-flowing glacier from De Long Mountains that deposited massive end moraine near mouth of Cutler River. Designated only in western part of 

map area. Because glacier may have responded to different controls, Cutler advance may not 

correlate with advances of early or late Sagavanirktok River age mapped in eastern part of 

map area

Sagavanirktok River or older glaciation

od Older drift (middle to early Pleistocene)—Bouldery till and gravel of uncertain composition, 

as described in unit sd. Lies beyond limits of glacial deposits of Cutler age in south-central 

part of map area. Generally forms featureless deposits buried beneath thick mantle of finegrained loess and colluvium. Commonly identifiable only by presence of erratic boulders in 

stream beds

Anaktuvuk River glaciation

ad Drift of Anaktuvuk River age (early Pleistocene)—Bouldery glacial deposits of uncertain 

composition overlain by continuous cover of organic silt (loess, solifluction, and thaw-lake 

deposits) generally more than 2–3 m thick. Erratic boulders consist only of most resistant 

rock types (quartzites and granites). Forms subdued till plains and low broad morainal ridges 

with gentle (1° to 2°) flanking slopes except where steepened by glacial erosion. Former 

swales and kettles generally filled with ice-rich, silty, organic colluvial and lacustrine 

deposits more than 5 m thick. Deeply and broadly dissected by streams. Designated only in 

northeastern part of map area

GLACIAL OUTWASH AND INWASH

Itkillik glaciation

io Outwash of Itkillik age, undivided (late Pleistocene)—Moderately well sorted and stratified 

sandy gravel; forms aprons and valley trains in front of moraines of Itkillik age and terrace 

remnants farther downvalley. Largest stones decrease in size from subrounded cobbles and 

very small boulders near moraine fronts to rounded to subrounded pebbles and granules 

farther downvalley

io3 Outwash of late Avan (late Itkillik Phase II) readvance (late Pleistocene)—Gravel aprons 

and valley trains, as described in unit io. Associated with or downvalley from end moraines 

assigned to late Avan readvance in Trail Creek valley and near Etivlik Lake. Also present 

near mouths of cirque-headed tributary valleys near head of Avan River. Generally lacks 

loess and peat cover, and is oxidized to depth of only 20–30 cm

io2 Outwash of Avan (Itkillik Phase II) age (late Pleistocene)—Sandy gravel, as described in 

unit io. Generally lacks loess cover. Forms terraces up to about 30 m high in front of end 

moraines of Avan (Itkillik Phase II) age on floor of upper Noatak valley and in valleys that 
18

traverse rugged highlands of De Long Mountains and in eastern part of map area. Stones 

etched, fractured, and pitted to 30–40 cm depth; oxidized to depths of 30–45 cm

io1 Outwash of Itkillik Phase I age (late Pleistocene)—Sandy gravel, as described in unit io. 

Generally has cover of silt, organic silt, and peat 0.5–4 m thick. Forms terraced aprons and 

valley trains beyond end moraines of Itkillik Phase I age, and also terrace remnants near 

head of Aklumayuak Creek. Commonly grades downvalley into thick sandy basin-fill deposits or silty glaciolacustrine deposits

io1C Outwash of late Anisak (late Itkillik Phase IC) age (late Pleistocene)—Sandy gravel, as 

described in unit io. Associated with end moraines of inferred late Anisak age. Forms terrace 

remnants in valley of Seagull Creek and near head of Nimiuktuk River

io1B Outwash of Anisak (Itkillik Phase IB) age (late Pleistocene)—Sandy gravel, as described 

in unit io. Associated with Anisak moraine and with other end moraines of inferred Anisak 

(Itkillik Phase IB) age

io1A Outwash of Makpik (Itkillik Phase IA) age (late Pleistocene)—Sandy gravel, as described 

in unit io. Associated with Makpik moraine and with other end moraines of Makpik (Itkillik 

Phase 1A) age

ii2 Inwash of Avan (Itkillik Phase II) age (late Pleistocene)—Well sorted to moderately sorted 

and stratified gravelly sand and sandy fine gravel; commonly grades upvalley into sandy 

gravel. Deposited near mouths of nonglaciated tributaries blocked by glaciers of Avan age. 

Forms benches and terraces that abut outer flanks of lateral moraines or outer faces of drift 

lobes

ii1 Inwash of Itkillik Phase I age (late Pleistocene)—Gravelly sand and sandy gravel, as described 

in unit ii2. Forms deposits that abut drift of Itkillik Phase I age

ii1B Inwash of Anisak (Itkillik Phase IB) age (late Pleistocene)—Gravelly sand and sandy 

gravel, as described in unit ii2. Forms deposits that abut drift of Itkillik Phase IB age

ii1A Inwash of Makpik (Itkillik Phase IA) age (late Pleistocene)—Gravelly sand and sandy 

gravel, as described in unit ii2. Forms deposits that abut drift of Itkillik Phase IA age

Sagavanirktok River glaciation

so Outwash of Sagavanirktok River age (middle Pleistocene)—Moderately well sorted and 

stratified gravel to sandy gravel. Forms trains and aprons beyond end moraines of Sagavanirktok River age in eastern part of map area. Commonly forms terraces up to 40 m 

high near moraine fronts. Stones generally weathered; and matrix generally oxidized to 

several meters depth. Typically covered by 1–2 m or more of loess, solifluction, and marsh 

deposits

so2 Outwash of late Sagavanirktok River age (middle Pleistocene)—Sandy gravel, as described in 

unit so. Associated with end moraines of late Sagavanirktok River age in eastern part of map 

area

so1 Outwash of early Sagavanirktok River age (middle Pleistocene)—sandy gravel, as described 

in unit so. Associated with drift of early Sagavanirktok River age in eastern part of map 

area

Cutler glaciation

co Outwash of Cutler age (middle Pleistocene)—Sandy gravel, as described in unit so. Forms 

terrace remnants associated with southern lateral moraine of Cutler advance near head of 

Aklumayuak Creek

BEDROCK SURFACE FORMS

[Bedrock units are differentiated on basis of surface morphology only, without consideration of age or 

composition]

B Bedrock, undifferentiated—Outcrops too small or too variable to classify, or intermediate in 

character between other bedrock surface forms. Relief generally moderate; most crests 

expose bare rock and most lower slopes vegetated. Talus generally rare to absent, and typically inactive where present
19

References Cited

Balascio, N.L., Kaufman, D.S., and Manley, W.F., 2005, 

Equilibrium-line altitudes during the last glacial maximum 

across the Brooks Range, Alaska: Journal of Quaternary 

Science, v. 20, p. 821–838.

Bigelow, N.H., and Powers, W.R., 2001, Climate, vegetation, 

and archaeology 14,000–9000 cal yr B.P. in central Alaska: 

Arctic Anthropology, v. 38, p. 171–195.

Boak, J.M., Turner, D.L., Henry, D.J., Moore, T.E., and Wallace, 

W.K., 1987, Petrology and K-Ar ages of the Misheguk 

igneous sequence—an allochthonous mafic and ultramafic 

complex—and its metamorphic aureole, western Brooks 

Range, Alaska, in Tailleur, Irv, and Weimer, Paul, eds., 

Alaskan North Slope geology: Anchorage, Alaska, Alaska 

Geological Society, p. 737–745.

Brigham-Grette, Julie, Gualtieri, L.M., Glushkova, O.Yu., Hamilton, T.D., Mostoller, David, and Kotov, Anatoly, 2003, 

Chlorine-36 and 14C chronology support a limited last 

glacial maximum across central Chukotka, northeastern 

Siberia, and no Beringian ice sheet: Quaternary Research, 

v. 59, p. 386–398.

Briner, J.P., Kaufman, D.S., Manley, W.F., Finkel, R.C., and 

Caffee, M.W., 2005, Cosmogenic exposure dating of late 

Pleistocene moraine stabilization in Alaska: Geological 

Society of America Bulletin, v. 117, p. 1108–1120.

 Brown, Jerry, Ferrians, O.J., Jr., Heginbottom, J.A., and Melnikov, E.S., 1997, Circum-arctic map of permafrost and 

ground-ice conditions: U.S. Geological Survey CircumPacific Map Series CP–45, scale 1:10,000,000.

Burch, E.S., Jr., 1990, The cultural and natural heritage of 

northwest Alaska; v. 1, Geology: Kotzebue, Alaska, NANA 

Museum of the Arctic, 479 p.

CAVM Team (D.A. Walker, Project Director), 2003, Circumpolar arctic vegetation map: Anchorage, Alaska, U.S. Fish 

and Wildlife Service, Conservation of Arctic Flora and 

Fauna (CAFF) Map No. 1, scale 1:7,500,000.

Childers, J.M., and Kernodle, D.R., 1981, Hydrologic reconnaissance of the Noatak River basin, Alaska, 1978: U.S. 

Geological Survey Open-File Report 81–1005, 38 p.

Clague, J.J., and Evans, S.G., 1994, Formation and failure 

of natural dams in the Canadian Cordillera: Geological 

Survey of Canada Bulletin 464, 35 p.

Combellick, R.A., Clement, R.F., and Cruse, G.R., compilers, 1993, Derivative geologic-materials map of the Baird 

Mountains quadrangle, Alaska: Alaska Division of Geological & Geophysical Surveys Public-Data File 93–52, 

scale 1:250,000.

Coulter, H.W., Hopkins, D.M., Karlstrom, T.N.V., Péwé, T.L., 

Wahrhaftig, Clyde, and Williams, J.R., 1965, Map showing extent of glaciations in Alaska: U.S. Geological Survey 

Miscellaneous Geologic Investigations Map I–415, scale 

1:2,500,000.

Curtis, S.M., Ellersieck, Inyo, Mayfield, C.F., and Tailleur, 

I.L., 1984, Reconnaissance geologic map of southwestern 

Misheguk Mountain quadrangle, Alaska: U.S. Geological 

Survey Miscellaneous Geologic Investigations Series Map 

I–1502, scale 1:63,360.

Dover, James, 1997a, Alaska resource data file—Howard Pass 

quadrangle: U.S. Geological Survey Open-File Report 

97–296, 47 p.

Ba Bedrock, alpine—Generally unweathered; forms steep-sided, sharp-crested ridges that have been 

sharpened by glacial erosion. Dissected by avalanche chutes and (at higher altitudes) by 

cirques and nivation basins. Lower flanks commonly mantled with talus and with debris fans 

at bases of avalanche chutes. Commonly includes stream deposits, talus rubble, and other 

colluvial deposits too small to designate separately

Be Bedrock exposed by stream erosion—Unweathered to slightly weathered; forms generally steep 

slopes along flanks of meltwater drainage channels or recently incised stream systems

Bg Bedrock, glacier-scoured—Smoothed and abraded by overriding glacier ice. May exhibit faceted ridge spurs, ice-marginal drainage channels, stoss-and-lee topography, U-shaped divide 

crossings, and other features characteristic of glacial erosion. Generally well exposed; commonly streamlined in direction of ice flow and channeled by meltwater. Black arrows show 

flow directions of ice; white arrows show flow directions of meltwater

Bs Bedrock, silt-covered—Moderate relief; silt cover generally present over all but the highest and 

steepest slopes. Most common near Pleistocene lake beds and other sources of airborne silt 

(loess), but also locally present where silt is generated by weathering of shale or other finegrained readily disaggregated rock

Bedrock, wave-eroded—Scoured by wave abrasion; has planed surface or series of terracelike 

surfaces, with scattered erratic clasts. Commonly associated with wave-cut notches and 

wave-built platforms. Mapped within and along north flank of Aniuk Lowland. Designated 

by diagonal line pattern
20

Dover, James, 1997b, Alaska resource data file—Misheguk 

Mountain quadrangle: U.S. Geological Survey Open-File 

Report 97–297, 18 p.

Dover, J.H., Tailleur, I.L., and Dumoulin, J.A., 2004, Geologic 

and fossil locality maps of the west-central part of the 

Howard Pass and part of the adjacent Misheguk Mountain 

quadrangles, western Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF–2413, 

scale 1:100,000, 3 sheets and 75-p. pamphlet.

Dumoulin, J.A., Harris, A.G., Blome, C.D., and Young, L.E., 

2004, Depositional settings, correlation, and age of carboniferous rocks in the western Brooks Range, Alaska: 

Economic Geology, v. 99, p. 1281–1306.

Edwards, M.E., Hamilton, T.D., Elias, S.A., Bigelow, N.H., 

and Krumhardt, A.P., 2003, Interglacial extension of the 

boreal forest limit in the Noatak valley, northwest Alaska: 

evidence from an exhumed river-cut bluff and debris 

apron: Arctic, Antarctic, and Alpine Research, v. 35, p. 

460–468.

Elias, S.A., Hamilton, T.D., Edwards, M.E., Begét, J.E., Krumhardt, A.P., and Lavoie, Claude, 1999, Late Pleistocene 

environments of the western Noatak basin, northwestern 

Alaska: Geological Society of America Bulletin, v. 111, p. 

769–789.

Ellersieck, Inyo, Curtis, S.M., Mayfield, C.F., and Tailleur, 

I.L., 1984, Reconnaissance geologic map of south-central 

Misheguk Mountain quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map 

I–1504, scale 1:63,360.

Ellis, J.M., and Calkin, P.E., 1984, Chronology of Holocene glaciation, central Brooks Range, Alaska: Geological Society 

of America Bulletin, v. 95, p. 897–912.

Ferrians, O.J., Jr., 1965, Permafrost map of Alaska: U.S. Geological Survey Miscellaneous Geological Investigations 

Map I–445, scale 1:2,500,000.

Gallant, A.L., Binnian, E.F., Omernik, J.M., and Shasby, M.B., 

1995, Ecoregions of Alaska: U.S. Geological Survey Professional Paper 1567, 73 p.

Hamilton, T.D., 1980, Surficial geologic map of the Killik River 

quadrangle, Alaska: U.S. Geological Survey Miscellaneous 

Field Studies Map MF–1234, scale 1:250,000.

Hamilton, T.D., 1981, Surficial geologic map of the Survey Pass 

quadrangle, Alaska: U.S. Geological Survey Miscellaneous 

Field Studies Map MF–1320, scale 1:250,000.

Hamilton, T.D., 1984a, Surficial geologic map of the Howard 

Pass quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF–1677, scale 1:250,000.

Hamilton, T.D.,1984b, Surficial geologic map of the Ambler 

River quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF–1678, scale 1:250,000.

Hamilton, T.D., 1986, Late Cenozoic glaciation of the central 

Brooks Range, in Hamilton, T.D., Reed, K.M., and Thorson, R.M., eds., Glaciation in Alaska—the geologic record: 

Anchorage, Alaska Geological Society, p. 9–49.

Hamilton, T.D., 1994, Late Cenozoic glaciation of Alaska, in

Plafker, George, and Berg, H.C., eds., The geology of 

Alaska: Boulder, Colorado, Geological Society of America, 

The Geology of North America, v. G–1, p. 813–844.

Hamilton, T.D., 2001, Quaternary glacial, lacustrine, and fluvial 

interactions in the western Noatak basin, northwest Alaska: 

Quaternary Science Reviews, v. 20, p. 371–391.

Hamilton, T.D., 2003, Surficial geologic map of parts of the 

Misheguk Mountain and Baird Mountain quadrangles, 

Noatak National Preserve, Alaska: U.S. Geological Survey 

Open-File Report 03–367, scale 1:250,000, 1 sheet and 

12-p. pamphlet.

Hamilton, T.D., 2009, Guide to surficial geology and river-bluff 

exposures, Noatak National Preserve, northwestern Alaska: 

U.S. Geological Survey Scientific Investigations Report 

2008–5125, 116 p.

Hamilton, T.D., and Brigham-Grette, Julie, 1992, The last 

interglaciation in Alaska—stratigraphy and paleoecology 

of potential sites: Quaternary International, v. 10–12, p. 

49–71.

Hamilton, T.D., Lancaster, G.A., and Trimble, D.A., 1987, 

Glacial advance of late Wisconsin (Itkillik II) age in the 

upper Noatak River valley—a radiocarbon-dated stratigraphic record, in Hamilton, T.D., and Galloway, J.P., eds., 

Geologic studies in Alaska by the U.S. Geological Survey 

during 1986: U.S. Geological Survey Circular 998, p. 

35–39.

Hamilton, T.D., and Van Etten, D.P., 1984, Late Pleistocene 

glacial dams in the Noatak valley, in Coonrad, W.L., and 

Elliott, R.L., eds., The United States Geological Survey in 

Alaska—accomplishments during 1981: U.S. Geological 

Survey Circular 868, p. 21–23.

Huston, M.M., Brigham-Grette, Julie, and Hopkins, D.M., 

1990, Paleogeographic significance of middle Pleistocene 

glaciomarine deposits on Baldwin Peninsula, northwest 

Alaska: Annals of Glaciology, v. 14, p. 111–114.

Karl, S.M., Aleinkoff, J.N., Dickey, C.F., and Dillon, J.T., 1989, 

Age and chemical composition of Proterozoic intrusive 

rocks at Mount Angayukaqsraq, western Brooks Range, 

Alaska, in Dover, J.H., and Galloway, J.P., eds., Geologic 

studies in Alaska by the U.S. Geological Survey, 1988: 

U.S. Geological Survey Bulletin 1903, p. 10–19.

Karl, S.M., Dumoulin, J.A., Ellersieck, Inyo, Harris, A.G., and 

Schmidt, J.M., 1989, Preliminary geologic map of the 

Baird Mountains and part of the Selawik quadrangles, 

Alaska: U.S. Geological Survey Open-File Report 89–551, 

scale 1:250,000, 1 sheet and 65-p. pamphlet.

Karlstrom, T.N.V., and others, 1964, Surficial geology of 

Alaska: U.S. Geological Survey Miscellaneous Geologic 

Investigations Map I–357, scale 1:1,584,000, 2 sheets.

Kaufman, D.S., Porter, S.C., and Gillespie, A.R., 2004, Quaternary alpine glaciation in Alaska, the Pacific Northwest, 

Sierra Nevada, and Hawaii, in Gillespie, A.R., Porter, 

S.C., and Atwater, B.F., eds., The Quaternary Period in 

the United States: Amsterdam, Elsevier Developments in 

Quaternary Science, v. 1, p. 77–103.

McCulloch, D.S., 1967, Quaternary geology of the Alaskan 

shore of the Chukchi Sea, in Hopkins, D.M., ed., The 

Bering Land Bridge: Stanford, Calif., Stanford University 

Press, p. 91-120. 

Matmon, A., Schwartz, D.P., Haeussler, P.J., Finkel, R., Lienkaemper, J.J., Stenner, H.D., and Dawson, T.E., 2006, 
21

Denali fault slip rates and Holocene-late Pleistocene kinematics of central Alaska: Geology, v. 34, p. 645–648.

Mayfield, C.F., Curtis, S.M., Ellersieck, Inyo, and Tailleur, 

I.L., 1984, Reconnaissance geologic map of southeastern 

Misheguk Mountain quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map 

I–1503, scale 1:63,360.

Mayfield, C.F., Curtis, S.M., Ellersieck, Inyo, and Tailleur, 

I.L., 1990, Reconnaissance geologic map of the De Long 

Mountains A–3 and B–3 quadrangles and parts of the A–4 

and B–4 quadrangles, Alaska: U.S. Geological Survey 

Miscellaneous Investigations Series Map I–1929, scale 

1:63,360, 2 sheets.

Mayfield, C.F., Ellersieck, Inyo, and Tailleur, I.L., 1987, Reconnaissance geologic map of the Noatak C5, D5, D6, and D7 

quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I–1814, scale 1:63,360. 

Mayfield, C.F., and Tailleur, I.L., 1978, Bedrock geologic map 

of the Ambler River quadrangle, Alaska: U.S. Geological 

Survey Open-File Report 78–120A, scale 1:250,000.

Mayfield, C.F., Tailleur, I.L., Albert, N.R.D., Ellersieck, Inyo, 

Grybeck, Donald, and Hackett, S.W., 1983, The Alaskan 

Mineral Resource Assessment Program—Background 

information to accompany folio of geologic and mineral 

resource maps of the Ambler River quadrangle, Alaska: 

U.S. Geological Survey Circular 793, 31 p.

Mayfield, C.F., Tailleur, I.L., and Ellersieck, Inyo, 1988, Stratigraphy, structure, and palinspastic synthesis of the western 

Brooks Range, northwestern Alaska, in Gryc, George, 

ed., Geology and exploration of the National Petroleum 

Reserve in Alaska, 1974 to 1982: U.S. Geological Survey 

Professional Paper 1399, p. 143–186.

Moore, T.E., Wallace, W.K., Bird, K.J., Karl, S.M., Mull, C.G., 

and Dillon, J.T., 1994, Geology of northern Alaska, in

Plafker, George, and Berg, H.C., eds., The geology of 

Alaska: Boulder, Colorado, Geological Society of America, 

The Geology of North America, v. G–1, p. 49–140.

Nelson, S.W., and Nelson, W.H., 1982, Geology of the Siniktanneyak Mountain ophiolite, Howard Pass quadrangle, 

Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF–1441, scale 1:63,360.

Saltus, R.W., Hudson, T.L., Karl, S.M., and Morin, R.L., 2001, 

Rooted Brooks Range ophiolite—implications for Cordilleran terranes: Geology, v. 29, p. 1151–1154.

Slack, J.E., Dumoulin, J.A., Schmidt, J.M., Young, L.E., and 

Romach, C.S., 2004, Paleozoic sedimentary rocks in the 

Red Dog Zn-Pb-Ag district and vicinity, western Brooks 

Range, Alaska—provenance, deposition, and metallogenic 

significance: Economic Geology, v. 99, p. 1385–1414.

Smith, P.S., 1913, The Noatak-Kobuk region, Alaska: U.S. Geological Survey Bulletin 536, 160 p.

Till, A.B., 1989, Proterozoic rocks of the western Brooks 

Range, in Dover, J.H., and Galloway, J.P., eds., Geologic 

studies in Alaska by the U.S. Geological Survey, 1988: 

U.S. Geological Survey Bulletin 1903, p. 20–25.

Till, A.B., Schmidt, J.M., and Nelson, S.W., 1988, Thrust 

involvement of metamorphic rocks, southwestern Brooks 

Range, Alaska: Geology, v. 16, p. 930–933.

Viereck, L.A., and Little, E.L., Jr., 1975, Atlas of United States 

trees; v. 2, Alaska trees and common shrubs: U.S. Department of Agriculture Forest Service Miscellaneous Publication no. 1293, 126 p.

Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska: 

U.S. Geological Survey Professional Paper 482, 52 p. 

Waitt, R.B., Jr., 1980, About forty last-glacial Lake Missoula 

jökulhlaups through southern Washington: Journal of Geology, v. 88, p. 653–679.

Walder, J.S., and Costa, J.E., 1996, Outburst floods from 

glacier-dammed lakes—the effect of lake drainage on flood 

magnitude: Earth Surface Processes and Landforms, v. 21, 

p. 701–723.

Washburn, A.L., 1980, Geocryology—A survey of periglacial 

processes and environments (2d ed.): New York, John 

Wiley & Sons, Halsted Press, 406 p.

Williams, Anita, 2000, Alaska resource data file—De Long 

Mountains quadrangle: U.S. Geological Survey Open-File 

Report 00–0023, 37 p.

Young, L.E., 2004, A geologic framework for mineralization in 

the western Brooks Range, Alaska: Economic Geology, v. 

99, p. 1281–1306.