Surficial Geologic Map 

of parts of the Misheguk Mountain 

and Baird Mountains Quadrangles, 

Noatak National Preserve, Alaska 

By Thomas D. Hamilton 

Pamphlet to accompany 

Open-File Report 03-367 

2003 

U.S. Department of the Interior 

U.S. Geological Survey 
2

INTRODUCTION 

PHYSICAL SETTING 

The map area, which comprises part of the Noatak 

National Preserve, includes approximately the southern 

two-thirds of the Misheguk Mountain quadrangle and the 

northern one-third of the Baird Mountains quadrangle. It 

is centered on a belt of west-trending lowlands along the 

Noatak River which separates the De Long Mountains to 

the north from the Baird Mountains to the south (Burch, 

1990, p. 196-201). The map area extends between the 

drainage divides which bound the Noatak drainage system 

to the north and south, separating that network from 

streams that flow north into the Arctic Ocean and south 

into the Kobuk River. An additional small segment in the 

southwest corner of the map area covers the upper drainage basin of Eli River, which flows west and then south to 

intersect the Noatak River about 50 km upvalley from 

Kotzebue Sound. 

 In addition to broad lowlands and isolated blocks of 

low mountains along the Noatak River and lower courses 

of its principal northern tributaries, the map area includes 

rugged highlands that rise to 4000-4500 ft (1225-1375 m) 

in the De Long Mountains1

. Highlands within the Baird 

Mountains are more subdued. They generally rise to only 

3000-3500 ft (900-1050 m), although Mt. Angayukaqsraq, 

in the southeast corner of the map area, rises to 4760 ft 

(1452 m). 

 Most of the map area is tundra-covered, but riparian 

stands of cottonwood (Populus balsamifera) are discontinuously present along the Noatak River and lower 

courses of its principal tributaries. Riparian spruce (Picea 

glauca) stands occur along the Noatak River in the extreme western part of the map area, where they extend 

upvalley to just above Noatak Canyon. All of the map 

area is underlain by continuous permafrost (Ferrians, 1965; 

Brown and others, 1997), which commonly is ice rich and 

occurs at shallow depths. 

HISTORY OF INVESTIGATIONS 

Initial geologic study of the Noatak River valley was 

undertaken in 1911 by a U.S. Geological Survey 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 U.S. 

Geological Survey (e.g., Tailleur and others, 1977). This 

work culminated in bedrock geologic maps that spanned 

the southern part of the Misheguk Mountain quadrangle 

(Curtis and others, 1984; Ellersieck and others, 1984; 

Mayfield and others, 1984) and the entire Baird Mountains 

 

1

 Elevations are presented in feet when taken directly from 

topographic maps. They are followed in parentheses by 

their calculated metric equivalents. 

quadrangle (Karl and others, 1989). A derivative map of 

construction materials within the Baird Mountains quadrangle has been compiled by Combellick and others 

(1993). 

 Regional syntheses of western Brooks Range geology 

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

and Moore and others (1994). Other geologic studies have 

dealt with the igneous and intrusive rocks of the map area 

(Boak and others, 1987; Karl and others, 1989; Till, 1989; 

Saltus and others, 2001). Mineral-resource data for the 

Misheguk Mountain and Baird Mountains quadrangles 

have been compiled by Dover (1997) and Williams (2000), 

respectively. 

 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. 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 Noatak 

River valley immediately east of the map area (Hamilton, 

1984a, 1984b) 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 analysis of a locally 

rich interglacial insect and vegetation record (Elias and 

others, 1999). An overview of the depositional record 

exposed in these bluffs reveals a complex history of interrelated glacial advances, stages of lake formation, and episodes of river downcutting (Hamilton, 2001). 

BEDROCK SURFACE FORMS 

The five bedrock divisions designated on the map 

refer to surface morphology, and only indirectly reflect 

bedrock composition. 

 Alpine bedrock (unit Ba) generally is underlain by 

resistant rock types, such as conglomerates, massive carbonates, and intrusive igneous rocks, that support relatively high, rugged uplands. Within the De Long 

Mountains and locally within the Baird Mountains, late 

Pleistocene glacial erosion has further steepened valley 

walls, sharpened ridge crests, and indented valley heads 

with cirque basins. Such bedrock areas are subject to 

rockfalls, landslides, snow avalanches, and other hazards 

characteristic of steep slopes. 

 Bedrock exposed by erosion (unit Be) is present both 

as narrow strips that highlight former meltwater channels 

and also as more extensive tracts along the Aklumayuak 

Creek and parts of the Noatak River that underwent late 

Pleistocene downcutting. The mapped distribution of this 
3

unit provides a useful guide to Pleistocene drainage 

changes, and would be helpful in locating bedrock exposures in areas generally covered by surficial deposits. 

Glaciated 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 (see map symbols), 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. 

In areas of silt-covered bedrock (unit Bs), upland surfaces 

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, which 

served as sources of windblown silt (loess) when the lakes 

were freshly drained and their floors not yet revegetated. 

Lake beds 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. 

 Areas designated B (undifferentiated bedrock) generally have characteristics intermediate between those of the 

other bedrock surface forms. They commonly contain 

isolated areas with other surface forms that are too small to 

map individually. 

THE PLEISTOCENE RECORD 

GLACIAL, LACUSTRINE, EOLIAN, AND FLUVIAL 

INTERACTIONS 

 Surficial geologic units and their relationships within 

the map area are compatible with the glacial-lacustrinefluvial model described by Hamilton (2001) for the Noatak 

basin. During each of several successive Pleistocene glaciations, glaciers developed at valley heads within the De 

Long Mountains; they expanded down south- to southeasttrending valleys and spread into lobes within lowlands 

along the Noatak River. Dammed by the lobes, large lakes 

formed and inundated the Noatak basin for as much as 50 

km upvalley (Hamilton, 2001). Although some of the 

older and larger larger lakes had outlets to the north and 

south from the Noatak basin, most probably filled and 

emptied repeatedly as their ice dams eroded or became 

buoyant (Walder and Costa, 1996; Hamilton, 2001). The 

resulting glacial outburst floods would have flowed westward down the Noatak River. 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 

surface 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 deposits at levels several tens of meters above present river 

level, whereas full-interglacial deposits appear at or 

slightly below the modern river (Elias and others, 1999; 

Hamilton, 2001). These interglacial deposits were buried 

and preserved beneath till-like sediments that formed during subsequent glacial and glacio-lacustrine episodes. 

 Smaller glaciers developed on local highlands within 

the Baird Mountains, but these were mostly restricted to 

valley heads. They locally crossed divides into upper valleys of the Kobuk drainage system, but generally did not 

extend northward far enough to intersect the lowlands 

along the Noatak River. 

GLACIAL NOMENCLATURE 

 A consistent set of terms has been employed for glacial-geologic mapping through the central Brooks Range 

(Hamilton, 1977, 1978, 1986, 1994; Hamilton and Porter, 

1975), and these terms have been extended into the present 

map area. The Sagavanirktok River glaciation is broadly 

equated with multiple glacial advances of middle Pleistocene age; the Itkillik glaciation with multiple advances 

during the late Pleistocene (table 1). However, glaciers in 

the De Long Mountains were nourished largely from moisture sources in the Bering Sea, and probably responded 

somewhat differently from central Brooks Range glaciers 

during each glacial cycle. Throughout the map area I have 

employed the unit designations used in the central Brooks 

Range to facilitate comparison with mapped areas farther 

east in the Noatak basin (Hamilton 1984a, 1984b). These 

map units also permit the use of generalized designations 

(for example, unit id) in cases where more age-specific 

designations (such as id1, id2, and id3) are not feasible. 

However, many glacial deposits within 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 

map-unit descriptions: the local moraine name followed in 

parentheses by its probable central Brooks Range equivalent (see table 1). 
4

Table 1. Glacial advances recognized in Misheguk Mountain and Baird Mountains quadrangles and their central Brooks 

Range equivalents. MIS, marine isotope stage 

Local Glacial Age 

Advance 

Map Unit Central Brooks Range Equivalent

Neoglacial nd Neoglaciation Late Holocene 

Unnamed id3 Late Itkillik II readvance Late Wisconsin 

(MIS 2) 

Avan id2 Itkillik II 

Unnamed id1C None recognized 

Anisak id1B Itkillik IB Early Wisconsin 

(MIS 4) 

Makpik id1A Itkillik IA Late interglacial 

(MIS 5d-5a) 

 Late Pleistocene 

Okak sd? Sagavanirktok River (late phase) Middle Pleistocene 

Cutler sd Sagavanirktok River Middle Pleistocene 

Unnamed older 

drift 

od Sagavanirktok River or older Middle Pleistocene or 

older 

GLACIER DAMMED LAKES 

 The lakes that formed during the Itkillik glaciation 

filled and drained dynamically rather than remaining at 

static levels. Their shoreline features therefore are weakly 

developed and difficult to trace. The deposits of the former lakes are recognizable as poorly drained, ice-rich, 

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, especially north 

and south of the Noatak River above Nimiuktuk River 

confluence, where unusually great fetch (span of open water) would have allowed wave action to be especially effective. Rare linear gravel outcrops aligned with the 

notches are interpreted as probable beach ridges. End moraines in some valleys become diffuse at a level that 

probably represents a contemporaneous lake stand; other 

end moraines are eroded to distinctive levels that represent 

lake stands during or after 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 

on the Noatak valley floor near the west margin of the map 

area (table 2). 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 or lake deposits of a given age can indicate the extent of contemporaneous glaciation, and former 

glaciated areas also are indicated by postglacial isostatic 

uplift of initially horizontal lake planes. 

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, and boulder weathering and other physical 

characteristics cannot be used to distinguish glacial deposits or glaciated bedrock surfaces of differing middle Pleistocene and older ages. 

 Broad U-shaped troughs that cross drainage divides 

along its north and south margins may be among the oldest 

glacial features recognized in the map area. Remnant 

patches of drift (unit (sd)) are evident on the floor of only 

one pass, but bedrock abraded by glacier ice (unit Bg) is 

more widely present in and around the passes, especially 

those carved from readily sculpted marble within the Baird 

Mountains. These ice-abraded surfaces exhibit smoothed
5

Table 2. Observed upper limits of lake deposits within Misheguk Mountain and Baird Mountains quadrangles 

Drainage Area Upper Lake Limit 

Feet Meters 

Map Unit 

Upper Anisak 1630–1650 

1400 

500 

430 

sgl 

igl1

Lower Anisak 1580–1600 

1300 

480 

400 

sgl 

igl1

Noatak above Nimiuktuk R. 1540 

1250 

1000 

470 

380 

300 

sgl 

igl1 

igl2

Nimiuktuk basin 1300–1350 

1100 

400–410 

340 

igl1 

igl2

Noatak between Nimiuktuk R. 

and Kaluktavik R. 

1500 

1250–1300 

1000 

460 

380–400 

300 

sgl? 

igl1 

igl2

Upper Kaluktavik 1300–1350 

1150 

400–410 

350 

igl1 

igl2

Lower Kaluktavik 1250–1300 

1100 

380–400 

340 

igl1 

igl2

Noatak between Kaluktavik R. 

and Kelly R. 

1300 

500

400 

150 

igl1 

igl2 (late phase) 

Upper Kugururok 1100–1150 340–350 igl2

Lower Kugururok 1150 

1050 

700–750 

550 

350 

320 

210–230 

170 

igl2 

igl2 (late phase) 

Lower Avan 1050–1060 

700 

550 

320 

210 

170 

igl2 (late phase) 

Upper Kelly 1300–1350 

1150 

400–410 

350 

igl1 

igl2

Lower Kelly 1000 

700 

500–550 

300 

210 

150–170 

igl2 (late phase) 

and streamlined ridges, faceted valley walls, and adjoining 

beveled uplands. The troughs along the north margin of 

the map area probably were eroded by outlet glaciers from 

an ice cap that covered much of the De Long Mountains. 

The troughs along the map area's south margin may have 

been outlets from smaller individual glacier complexes 

around prominent highlands such as Mt. Angayukaqsraq, 

Kanaktok Mountain, and other peaks near the heads of Eli 

River and the North Fork of Squirrel River. Drift patches 

and isolated erratic stones must originally have been present on the ice-sculpted surfaces, but they must have been 

eradicated during a long span of postglacial weathering. 

 An extensive blanket of featureless drift (unit od) that 

lies beyond Cutler-age deposits in the southeastern part of 

the map area is inferred to represent a glaciation of early or 

middle Pleistocene age that preceded the Cutler advance. 
6

It is contiguous with drift remnants that were mapped beyond the Cutler moraine in southern parts of the adjoining 

Noatak basin (Hamilton, 1984b). 

 The Cutler advance represents a distinctive event of 

middle Pleistocene age. Its end moraine, which intersects 

the Noatak River near the mouth of Cutler River 30 km 

east of the map area, was originally assigned to the late 

Pleistocene Itkillik glaciation (Hamilton, 1984b), but subsequent stratigraphic studies of bluff exposures along the 

Noatak River have shown that deposition of this moraine 

preceded the last interglaciation and therefore is assignable 

to the middle Pleistocene (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 in Kotzebue 

Sound. 

 South of the Noatak River, the Cutler moraine is 

traceable westward from its terminus into the map area 

near Lake Kangilipak, where its outer flank is continuous 

with the outer limit of drift unit sd. Farther west, in the 

south-central part of the map area, featureless drift that lies 

south of the Noatak River beyond Itkillik glacier limits 

may also be of Cutler age. These deposits outline an ice 

margin that extended southward from the De Long Mountains across the Noatak River valley into uplands and valleys of the northern Baird Mountains, overriding most of 

the valley through a stretch of perhaps 150 km. 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. 

 In the northeast part of the map area, drift of probable 

Cutler age east of the upper Nimiuktuk River (unit sd) outlines a large glacier that flowed southeastward, perhaps 

draining the eastern margin of a De Long Mountains ice 

cap. Glacier-scoured bedrock in the western part of the 

Iggiruk Mountains probably was overridden at the same 

time because the orientations of grooved and streamlined 

features 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, which intersects the Noatak River at Okak Bend, about 20 km east of 

the map area (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 lake deposits of inferred middle Pleistocene 

age are widespread in the Ambler River and Howard Pass 

quadrangles (Hamilton, 1984a, 1984b), comparable deposits in the map area have been largely obliterated by 

younger glacial advances. Lake deposits of this age (unit 

sgl) are widely exposed only in the upper Anisak River 

valley near the northeast corner of the map area. They rise 

here to a maximum altitude of about 1650 ft (500 m), and 

truncate or overlap end moraines of inferred Cutler age 

along Setting Sun and Stone Ring Creeks. The water 

plane declines southward to about 1600 ft (490 m) asl east 

of the lower Anisak River (just beyond the east margin of 

the map area), and it may have stood at about 1540 ft (470 

m) asl near the southeast corner of the map area; its 

upwarping to the north probably reflects isostatic recovery 

from crustal depression beneath glaciers in the De Long 

Mountains. The lake's outlet may have been through 

Howard Pass, whose floor was at about 520 m asl, because 

isostaticaly warped water planes rise eastward across the 

Noatak basin (Hamilton, 2001). A local meltwater drainage channel near present-day Lake Kangilipak issues from 

the outer flank of a Cutler-age moraine at an altitude of 

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

Aklumayuak Creek. Aklumayuak Creek must have been 

established as a major meltwater outlet channel during 

Cutler time. Because evidence for lake stands at comparable heights is absent from all parts of the map area farther 

to the west, extensive glaciers must have covered most of 

this part of the De Long Mountains and the Noatak River 

valley at this time. 

LATE PLEISTOCENE GLACIATIONS 

 Five successively less extensive glacial advances of 

late Pleistocene age developed within the De Long Mountains (see table 1). Several can be traced into named end 

moraines that cross the Noatak valley center, but relationships are not always clear because of the extensive glaciallake deposits that fill low-lying areas along the Noatak and 

lower parts of its principal northern tributaries. The moraine succession postdates deposition of the lastinterglacial Old Crow tephra, and therefore is assignable to 

the Itkillik glaciation (Hamilton, 2001). The two oldest 

advances of the succession created the Makpik and Anisak 

moraines, which cross the Noatak valley floor 14 km east 

of the map area and at the map area's eastern boundary, 

respectively. Much less extensive younger glacial advances issued from source areas within the De Long 

Mountains. By analogy with the central Brooks Range 

glacial sequence, the principal drift units assigned to these 

advances have been termed Itkillik IA, Itkillik IB, and Itkillik II (table 2), and are labeled id1A, id1B, and id2 on the 

map. A very localized readvance or stillstand toward the 

end of Itikillik I time is labeled id1C (a term new to this 

map); a limited readvance of late Itkillik II age (recognized 

widely the Brooks Range) is labeled id3. 

 Late Pleistocene glaciation within the Baird Mountains was restricted to a few isolated highlands, and consequently is discussed separately at the end of this section. 

Glaciations and related events 

of Itkillik I age 

 The Makpik and Anisak advances are most clearly 

differentiated in the east-central part of the map area, 
7

where large compound lateral moraines outline successive 

ice lobes that flowed southeastward out of Nimiuktuk 

River valley. The outer lobe (unit id1A) extended beyond 

the map area and 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 

moraine, formed during a subsequent stillstand or readvance, intersects the Noatak River 11 km farther west. 

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 a narrow bedrock-bounded passageway. The limit of the older (id1A) advance of the western 

lobe is obscured by glaciolacustrine deposits, but the glacier may have extended down the Noatak to the vicinity of 

Kaluktavik River to become confluent with ice flowing 

south down that drainage system. The younger (id1B) advance of the western lobe terminated about 6 km above the 

mouth of Aklumayuak Creek, where it formed an end moraine across the valley floor. 

 Glaciers of Itkillik I age farther west formed major 

south-flowing systems that filled the Kugururok and 

Kaluktavik drainages. Patches of drift and expanses of 

ice-scoured bedrock (bedrock unit Bg) are exposed locally 

above the limits of widespread glacial-lake deposits. End 

moraines generally are buried beneath the blanket of lacustrine sediments, but commonly are evident as subdued 

arcuate ridges (see map symbol). 

 Glacial-lake deposits of Makpik and Anisak age cannot be differentiated from each other, so are shown together as unit igl1. These deposits extend widely through 

the map area beyond the limits of younger glaciolacustrine 

sediments (unit igl2). In the upper Anisak drainage the 

limit of Itkillik-age lake deposits is at about 1400 ft (430 

m) altitude, and a series of fan-delta deposits occurs along 

the former north shore of the lake. Within the Nimiuktuk 

lobe the lake limit is at about 1200-1300 ft (370-400 m) 

both north and south of the Noatak River, and is associated 

with wave-eroded notches and sparse beach deposits (unit 

b) along the inner flanks of id1A moraines. The 1200-1300 

ft (370-400 m) lake limit remains unchanged westward 

down the Noatak River and through the lower Kaluktavik 

valley, but farther north up Nimiuktuk valley it rises to 

1300-1350 m (400-410 m). Elevated lake limits in northern and northeastern parts of the map area probably reflect 

ice load in the De Long Mountains and farther east in the 

central Brooks Range. Lake deposits at comparable levels 

are generally absent from the De Long Mountains between 

the Kelly River to the west and Imikneyak Creek to the 

east. This sector of the mountains may have still been icecovered when the lake existed. 

 Through the eastern part of the map area, the lake 

level must have been controlled by an overflow channel at 

about 1300 ft (400 m) asl that extended southward into 

Aklumayuak Creek from the id1A moraine south of Lake 

Kangilipak. Drainage from Aklumayuak Creek then 

flowed westward down the Noatak River valley, skirting 

southern ice margins. During much of Itkillik I time, glaciated highlands through the central part of the map area 

may have divided glacier-dammed lakes into eastern and 

western compartments that were controlled by separate 

outlets. In west-central parts of the map area, deposits of 

inferred igl1 age along lower valley walls are heavily 

modified by solifluction and dissected by erosion. The 

water body that formed those deposits may have drained 

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

Ahliknak Creek near the southwest corner of the map area. 

 A limited stillstand or readvance of glaciers took place 

near the close of Itkillik I time. Glaciers generated on and 

around Black Mountain 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 1350 

ft (410 m), the characteristic upper limit for lakes of Itkillik I age in this part of the map area. The drift therefore 

cannot be younger than the lake phases of Itkillik I glaciation. 

Glaciation and related events 

of Itkillik II age 

 The Itkillik II ice advance is broadly equated with late 

Wisconsin glaciation and dated between about 24,000, and 

11,000 14C years B.P. (Hamilton, 1986). During Itkillik II 

time, the moisture necessary to nourish glaciers was extremely limited in highlands around the Bering Straits owing to glacio-eustatic sealevel depression and consequent 

subaerial exposure of the broad Bering Platform (Burch, 

1990, p. 45-47). 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. In central to north-central parts of the map area, short glaciers 

radiated from Misheguk Mountain, Mount Bastille, and 

other unnamed highlands that rise to 3500-4500 ft (1075-

1375 m) altitude. These glaciers terminated within the 

mountain valleys of Tumit, Okotak, and Trail creeks and at 

the heads of Kaluktavik and Kugururok rivers. Farther 

west, in lower source areas (3000-4000 ft; 925-1225 m) 

flanking Avan River valley, numerous cirques generated 

an unusually large valley glacier that flowed south, crossed 

the Noatak valley floor near the west margin of the map 

area, and built the Avan moraine. The Avan valley area 

must have been subjected to much heavier snowfall at this 

time relative to highlands just a few tens of kilometers to 

the east. 
8

 During this interval, extensive lowlands remained icefree but were inundated by lakes. A glacier-dammed lake 

(unit igl2) occupied the broad valley floor around the 

Nimiuktuk-Noatak valley confluence. Around its shores, 

wave-eroded notches formed at altitudes of about 1000 ft 

(300 m) along the lower flanks of moraines of the Itkillik 

IB (unit id1B) drift complex. Deposits of this glacial lake 

are traceable up Nimiuktuk valley and its tributaries, terminating in each drainage where the valley floor rises 

above 1100 ft (340 m) altitude. Extensive lake deposits 

that cover lower-lying valley floors farther west onlap adjoining lowlands and valley sides to about 1000-1050 ft 

(300-320 m) asl. Their upper limits are marked by abrupt 

contacts between little modified lake sediments below and 

more strongly soliflucted and dissected older deposits 

above. Near Avan River and farther north up the Kugururok, Kagvik, and Kalaktavik valleys the younger lake 

limit rises to 1100 ft (340 m) and locally to 1150 ft (350 

m) asl, probably because of postglacial isostatic recovery 

in these more intensely glaciated parts of the map area. An 

eastern arm of the glacier-dammed lake may have extended into the Lake Kangilipak basin, where an abandoned channel that heads at 1000 ft (300 m) altitude and 

trends south into the Aklumayuak drainage may have 

served as its outlet. Near the west margin of the map area, 

a pass at about 925 ft (280 m) altitude would have allowed 

drainage from the lake to flow south and then west around 

the Avan moraine. 

 Evidence for lower lake stages occurs in the southwest 

corner of the map area, where the Avan moraine has been 

incised to heights locally as great as 1050 ft. The lake then 

stood at successively lower levels between about 750 and 

500 ft (230 and 170 m) during thinning and wastage of its 

ice dam. 

 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 frostshattered 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. 

Glaciation in the Baird Mountains 

 Only a few small glaciers of late Pleistocene age were 

generated within the Baird Mountains. Their advances 

were marked by moraines and outwash near valley heads 

and by adjoining freshly ice-scoured surfaces. The most 

extensive advance, about 8 km in length, issued from a 

cirque in rugged but unnamed highlands at the head of 

Akikukchiak Creek (14 km south of Tututalak Mountain). 

Outwash that spilled eastward from this advance formed a 

local terrace 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 east 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 associated with abraded and channeled bedrock occur a few 

kilometers beyond the limits of Itkillik-age drift in the two 

other localities described above. 

THE PLEISTOCENE-HOLOCENE 

TRANSITION AND LATER HOLOCENE 

EVENTS 

 A final readvance of alpine glaciers in the De Long 

Mountains generated end moraines (unit id3) near the 

mouth of a cirque-headed tributary valley at the north 

flank of Misheguk Mountain and in several mounain valleys between headward parts of Trail and Tumit creeks and 

near the head of Avan River. Patches of drift (units d and 

d?) on the floors of these valleys and neighboring steep 

mountain valleys may also date from this interval. By 

analogy with the central Brooks Range glacial record 

(Hamilton, 1986), this readvance may have taken place 

between about 12,800 and 11,500 14C yr B.P. 

 Because of the high seasonal discharge of the Noatak 

River (Childers and Kernodle, 1981) incision through lake 

deposits of Itkillik II age probably was rapid. However, as 

the river continued downcutting, it would have been superimposed on bedrock along parts of its course, and would 

have been held for some time at that level until it could 

incise the bedrock barrier. Because of the map's small 

scale, it cannot show every individual river terrace that 

was formed during downcutting. Therefore I have combined those terrace remnants into 2-3 general terrace levels 

within each of four reaches of the Noatak River (table 3). 

 The highest terrace level (designated tg1) occurs along 

the entire length of the Noatak River across the map area. 

It most commonly stands about 50 m above modern river 

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

sectors of the river (table 3). It must have formed when 

stagnant glacier ice was still present on the valley floor, 

because at several localities (for example, at the mouth of 

Nimiuktuk River) 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 

Noatak Canyon caused outburst floods that drained the 

lake.
9

Table 3. Terraces along Noatak River and its principal tributaries within Misheguk Mountain and Baird Mountains 

quadrangles 

Drainage Terrace Level (m) Map Unit Comments 

Above Nimiuktuk R. 50 

40 

25 

15 

8 – 10 

tg1

---- 

---- 

tg3

tg4

Widespread 

Local 

Local 

Widespread 

Extensive around New Cottonwood Cr. 

Nimiuktuk R. to 

Aklumayuak Cr. 

52 – 44 

19 – 25 

10 

tg1

tg2

---- 

Widespread 

Common near Aklumayuak Cr. mouth 

Local 

Aklumayuak Cr. to 

Noatak Canyon 

40 – 60 

30 – 35 

15 

10 

tg1

tg2

tg3

al1

Widespread 

Extensive around mouth of Sisiak Cr. 

Common 

Recent floodplain 

Noatak Canyon to 

Kelly R. 

45 – 50 

25 

15 

tg1

---- 

tg3

Widespread 

Local 

Common 

 Terraces at about 25-35 m height (designated tg2) are 

most extensive along the Noatak River near the mouths of 

Aklumayuak and Sisiak Creeks. Terrace remnants at 

comparable levels occur sparsely elsewhere, but generally 

are too small to map. Two radiocarbon ages of about 

13,310 and 13,370 14C yr B.P. were obtained from a 25-

meter terrace near the mouth of Aklumayuak Creek (table 

4), and a 35-m bluff a short distance downvalley yielded a 

similar age of about 13,140 yr B.P. The Noatak River 

must have been downcutting through an interval about 35-

25 m above its modern level at about 13,500-13,000 14C yr 

B.P. Radiocarbon ages representing this time span are 

relatively common within the central Brooks Range, 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. 

 Widespread terraces at about 15 m height (designated 

tg3) are present along stretches of the Noatak River above 

Nimiuktuk River and below Aklumayuak Creek (table 3). 

Bluff deposits standing 20 m high near the west margin of 

the map represent a probably comparable or slightly older 

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

about 9,220 and 9,360 14C yr B.P. (table 4). The thaw features, which formed under higher summer temperatures of 

the early Holocene warm interval (Bigelow and Powers, 

2001), do not date river levels directly but provide a minimum limiting age on river downcutting. 

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

m height around the mouth of Little Cottonwood Creek 

and along Kugururok River opposite Lake Kaiyak. Although alluvial surfaces at this level are present elsewhere, 

they are too small to map separately or are indistinguishable from higher floodplain deposits (unit al1). 

 Glacial deposits of late Holocene (Neoglacial) age are 

common in cirques through the central Brooks Range 

(Ellis and Calkin, 1984), but generally they only occur 

within short distances of the termini of present-day glaciers. Modern glaciers are not present in the map area, and 

consequently drift of Neoglacial age is rare. Several very 

small deposits that may be of this age (unit nd) occur at the 

bases of steep north-facing cirque headwalls in highlands 

between headward parts of Trail and Tumit creeks; and 

one other deposit that may be of comparable age is present 

in highlands that form 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 must be 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. 
10

Table 4. Radiocarbon ages from alluvial terrace deposits along Noatak River within Misheguk Mountain and Baird 

Mountains quadrangles 

Age and Lab. Number Material and Setting Location

9,220 ±40 

(Beta-156899)

Wood and small plant fragments 

from basal peat in thaw depression 

20-m bluff. North side Noatak R. 2 km 

above Kelly Ranger Station 

9,360 ±40 

(Beta-156902)

Wood in probable thaw-lake deposit Slip-off slope at downstream end of 20-m 

bluff at above location 

13,140 ±40 

(Beta-156900)

Wood fragments from woody peat 

1.1 m below surface 

35-m bluff, south side Noatak R. 4.5 km 

downvalley from Sapun Creek 

13,310 ±40 

(Beta-156904)

Wood from pod of organic detritus 

near base of floodplain sand that 

caps alluvial gravel 

25-m bluff 1.5 km above Aklumayuak Cr. 

13,370 ±50 

(Beta-156903)

Rodent feces from same pod of 

detritus as described above 

As above 

ACKNOWLEDGEMENTS 

 The U.S. National Park Service, through the efforts of 

Robert Gal, provided logistical and financial support for 

field mapping and subsequent preparation of this report 

and accompanying map. Field assistance during boat traverses down the Noatak River was provided by George 

Lancaster in 1986 and Toby Wheeler in 2000, and Julie 

Esdale assisted with helicopter-supported field mapping 

during 1999 and 2003. Grateful thanks also to helicopter 

pilots Ed Gunter and Tony Herby for skillful flying in frequently wretched weather conditions. Keith Labay, who 

created the accompanying digital map and GIS files, provided valuable input on color schemes, electronic symbols, 

and layout. Thanks also to Susan Karl for her thorough 

and thoughtful review of the map and report.

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