Aniralik

Lake

Lake

Kangilipak

Burial

Lake

I g g i r u k

M o u

n t a i n s

A n i s a k

R i v e r

C r e e k

New

Cottonwo

od

Creek

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id1

OPEN-FILE REPORT 03-367

Version 1.0

Surficial geologic map of parts of the Misheguk Mountain and

Baird Mountains quadrangles, Noatak National Preserve, Alaska

Pamphlet accompanies map

68o40' 159o

00'

68o00'

50'

10'

20'

30'

30' 

LIST OF MAP UNITS

[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 over known or inferred deposits of the second unit. Units of either type are described below only where additional explanation is necessary. Units queried where uncertain.]

BEDROCK SURFACE FORMS

Bedrock, undifferentiated—Bedrock intermediate in character between alpine and

silt-covered. Moderate relief, with most crests exposing bare rock and most lower

slopes vegetated. Talus rare to absent, and generally inactive where present

Bedrock, alpine—Generally unweathered bedrock, forming steep-sided, sharp-crested

ridges. 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

Bedrock exposed by erosion—Unweathered to slightly weathered rock, forming generally steep slopes along flanks of meltwater drainage channels or recently incised

stream systems. Most common along Noatak River and its lower tributaries

Bedrock, glaciated—Bedrock 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 rock surfaces; commonly streamlined in direction of

ice flow and channeled by meltwater (arrows show flow directions of ice and

meltwater)

Bedrock, silt-covered—Bedrock of moderate relief, with 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 fine-grained readily disaggregated rock

FAN DEPOSITS

Deposits of steep alpine fans—Coarse, very poorly sorted, subangular to subrounded

silty sandy gravel at mouths of avalanche chutes and steep canyons. Upper segments 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 12o to 25o

, intermediate

between those of alluvial fans and talus cones

Inactive alpine fan deposits—As described in unit af. Generally weathered and

covered with sod and vegetation

Fan deposits—Range from poorly sorted, weakly stratified, subangular, silty, sandy

coarse gravel at mouths of mountain valleys to gravelly sand and silt within lowlands

Active fan deposits—As described in unit f. Employed only on compound fans to

distinguish active from inactive elements

Inactive fan deposits—As described in unit f. Generally weathered and covered

with sod and vegetation

Fan-delta deposits—Alluvial-fan deposits (as described in unit f) that grade downslope into deltaic and lacustrine facies (well sorted and generally well stratified

sand and silt, with some fine gravel locally present

ALLUVIUM

Alluvium, undivided—Varies from moderately sorted, stratified, coarse gravel in upper valleys to muddy fine gravel and gravelly mud along lower river courses.

Along smaller streams, unit includes fan, flood-plain, and low terrace deposits that

are too small to be designated separately

Modern alluvium—Gravel to gravelly mud, as described in unit al, generally unvegetated and subject to annual flooding. Differentiated only along principal streams

Low alluvial-terrace deposits—Gravel to gravelly mud, as described in unit al, mantled with 0.3-1 m of silt, sand, turf, and peat, and generally vegetated. Forms terraces generally within 3-4 m of modern stream levels. Differentiated only along

principal streams

Gravel deposits, undifferentiated—Isolated, gravelly erosion remnants of uncertain

composition and origin

TERRACE DEPOSITS

Terrace gravel—Alluvial gravel and sandy gravel, generally 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

Terrace gravel, lowest-level—Alluvial gravel, as described in unit tg. Forms broad al

Rock-glacier deposits, active—Very poorly sorted, nonstratified, coarse angular

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

Upper surfaces generally unvegetated, unweathered to moderately weathered, and

with lichen cover sparse. Frontal slopes barren, steep, and highly unstable, meeting upper surfaces at abrupt angle. Form lobate deposits at base of talus cones

within cirques or along valley walls

Rock-glacier deposits, inactive—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

Talus rubble—Angular, unsorted rock debris, as described in unit tra, with activity

undetermined or with active and inactive components too small to be mapped

separately

Talus rubble, active—See Map Symbols

Talus rubble, inactive—Angular rock debris, as described in unit tra, generally

weathered and lichen covered, and with partial sod cover

SILT DEPOSITS

Ice-rich silt deposits—Silt deposits, commonly with ice-wedge polygon networks,

more than 1-2 m thick in swales and other depressions. Mapped only east of Nimiuktuk River opposite mouth of Kukukpilak Creek

Upland silt deposits—Poorly to moderately sorted, generally unstratified, silt, organic

silt, and slightly stony silt draped over uplands of low to moderate relief. Represents loess mixed by frost action with local organic matter and weathering products. Commonly grades downslope into thick, massive, organic-rich silt or into

solifluction deposits

LACUSTRINE AND GLACIOLACUSTRINE DEPOSITS

Beach deposits—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. Mapped along

modern shore of Lake Narvakrak. Possible ancient beach deposits (unit b?) occur

at edge of glacial-lake deposits (unit igl2) north of Noatak River near New Cottonwood Creek

Deltaic deposits—Generally well stratified sand and sandy fine gravel deposited by

streams at lake margins. Commonly build outward into lake, and overlie finegrained lacustrine deposits. Mapped only at southeast corner of Lake Kangilipak

Lacustrine deposits—Clayey silt, silt, and sand, commonly well stratified, grading into sand and gravelly sand near former shorelines and sandy fine gravel near former river mouths. Mapped primarily along receding lake margins or beds of

lakes that have recently drained. Commonly include beach deposits too small to

be designated separately

Thaw-lake deposits—Weakly stratified to nonstratified silt, organic silt, and clayey to

sandy silt; generally contains abundant ice as lenses, wedges, and interstitial

grains. Fill thaw basins in glacial-lake deposits on floors of Noatak, Kugururok,

and Nimiuktuk valleys

Glacial-lake deposits of Itkillik age—Stratified silt, clayey silt, and silty fine sand,

commonly with dispersed dropstones. Grades into gravelly sand to sandy fine

gravel near former stream mouths. Mapped as compound unit (for example,

igl/B, igl/id1, igl/io1) where drapes or overlies bedrock or other glacial deposits

Glacial-lake deposits of Avan (Itkillik Phase II) age—Glacial-lake deposits, as described in unit igl, that formed behind moraine dam at mouth of Avan River.

Form extensive deposits at altitudes up to 300-320 m (1000-1050 ft) along Noatak River and lower to middle parts of its tributary valleys. Mapped as compound

unit (for example, igl2/B, igl2/id, igl2/id1) where it drapes or overlies bedrock or

other glacial deposits. Arcuate symbols designate end moraines of preceding glacial advances that later were draped by lake deposits. Upper limits are locally

marked by wave-cut scarps

Glacial-lake deposits of Anisak (Itkillik Phase IB) age—Glacial-lake deposits, as

described in unit igl, that formed beyond Anisak moraine or during ice recession

from Anisak moraine. Locally present at altitudes up to 400 m (1300 ft) beyond

limits of unit igl2. Widely present on floor of Anisak River valley and along both

flanks of Noatak River valley east of Nimiuktuk River, where wave-cut scarps

separate it from unit igl2. Mapped as compound unit (for example, igl1/id1,

igl1/io1) where it drapes or overlies other glacial deposits

Glacial-lake deposits of Cutler (Sagavanirktok River) age—Glacial-lake deposits,

as described in unit igl, that formed beyond moraines of probable Cutler age in

Anisak River valleyPresent to altitudes up to about 460 m (1500 ft) beyond lim

Drift of Itkillik Phase I, undivided—Glacial deposits, as described in unit id. Morphology rugged to subdued, depending on relations to ice-dammed glacial lakes.

Common in lower parts of Kugururuk and Kaluktavik River valleys and along

Noatak River valley upstream from Aklumayuak Creek

Drift of late Aniuk (Itkillik Phase IC) age—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

Drift of Aniuk (Itkillik Phase IB) age—Glacial deposits, as described in unit id,

that extend into Aniuk moraine, a prominent end moraine at mouth of Aniuk River near east margin of map area. Overlapped by glacial-lake deposits (units igl2

and igl1) to altitudes of about 400 m (1300 ft). Differentiated from unit id1A

primarily along Noatak River upvalley from Aklumayuak Creek confluence

Drift of Makpik (Itkillik Phase IA) age—Glacial deposits, as described in unit id,

that extend east up Noatak River valley into Makpik moraine, a prominent end

moraine at mouth of Makpik River beyond east margin of map area

Ice-stagnation (kame) deposits—Thick and extensive water-washed sand and gravel

deposited in contact with stagnating glaciers of Itkillik I age. Commonly forms

conical to subdued mounds with well-drained surfaces. Mapped only near heads

of Analak, Sisiak, and Aklumayuak creeks

Ice-contact meltwater deposits—Meltwater-washed sand and gravel, as described in

unit ik, commonly associated with 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

Aniuk (unit id1B) advance north and south of Noatak River near east margin of

map area

Outwash of Itkillik age, undivided—Moderately well sorted and stratified sandy

gravel forming 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

Outwash of late Avan (late Itkillik Phase II) readvance—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. Also present near mouths

of cirque-headed tributary valleys near head of Avan River

Outwash of Avan (Itkillik Phase II) age—Sandy gravel, as described in unit io. Primarily associated with end moraines of Avan age (unit id2) in mountain valleys

close to rugged highlands in north-central part of map area

Outwash of Itkillik Phase I—Sandy gravel, as described in unit io. Forms apron beyond end moraine of Itkillik I age near head of Little Cottonwood Creek and terrace remnants near head of Aklumayuak Creek

Outwash of late Aniuk (late Itkillik Phase IB) age—Sandy gravel, as described

in unit io, associated with end moraines of inferred late Aniuk age. Forms terrace remnants in valley of Seagull Creek and near head of Nimiuktuk River

Outwash of Aniuk (Itkillik Phase IB) age—Sandy gravel, as described in unit io, associated with end moraines of inferred late Aniuk age near head of Sisiak Creek

Sagavanirktok River glaciation

Drift of Cutler (Sagavanirktok River) age—Poorly sorted nonstratified till, probably ranging 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 organic silt (loess, solifluction, and muskeg deposits), but crests of some ridges and knolls expose weathered gravel and erratic

boulders of resistant lithologies. Mapped mainly in eastern parts of map area

Outwash of Cutler (Sagavanirktok River) age—Moderately well sorted and stratified gravel to sandy gravel, commonly oxidized to several meters depth. Forms

terrace remnants in front of end moraines of probable Cutler age (unit sd) near

heads of Aklumayuak Creek and a northern tributary to that creek

Sagavanirktok River or older glaciation

Older drift—Till and gravel, as described above. Forms featureless deposits buried

beneath thick mantle of fine-grained loess and colluvium. Commonly identifiable only by presence of erratic boulders in stream beds

MAP SYMBOLS

Boundary of Noatak National Preserve

Sagavanirktok

River

glaciation

Phase

I

Phase

II

Itkillik

glaciation

Neoglaciation

Pleistocene

Holocene

QUATERNARY

CORRELATION OF MAP UNITS

Fan deposits Alluvium Terrace

deposits

Colluvial deposits Silt deposits Lacustrine and

glaciolacustrine deposits

Other glacial deposits

afi

f

fi

fd

al

al1

al2

gr

tg

b

dt

sgl

igl

l

igl1

igl2

sd

so

rgi

tr

tri

si

us

ik

io

id1A

io2

io1

io1C

af

fa

tl

io3

i-c

B

Ba

Be

Bg

Bs

id1

id1B

id1C

rga

io1B

tg4

fd

al

al2

al1

gr

tg

tg1

tg2

tg3

c

fl

pr

rga

rgi

tra

tri

si

us

b

b?

l

igl

igl

2

igl

1

sgl

idt

sdt

d

sd

id

id1

id2

id1A

id1B

ik

io

so

io1

io2

io1C

cm

s

tl

nd

id3

id1C

i-c

io3

fa

fi

f af

afi

io1B

tg4

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?

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od

od

?