MISCELLANEOUS FIELD STUDIES MAP MF–2409 Version 1.0 Surficial geologic map of the Bettles quadrangle, Alaska Pamphlet accompanies map ALASKA QUADRANGLE LOCATION SCALE 1: 250 000 0 25 KILOMETERS 20 15 10 5 5 0 20 15 10 5 5 25 MILES SURFICIAL GEOLOGIC MAP OF THE BETTLES QUADRANGLE, ALASKA By Thomas D. Hamilton 2002 Geology by W.W. Patton, Jr. and T.P. Miller, 1966-70; R.A. Kreig and R.D. Reger, 1972-75; and T.D. Hamilton, 1962- 66, 1970-74, and 1983-87 Digital representation by Earth Satellite Corporation, 1999; Greenhorne & O'Mara, 1999; K.A. Labay, Raytheon ITSS contractor, 2000-2002 Edited by Jane S. Ciener Approved for publication September 30, 2002 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters and between X and Y dimensions on the same plotter, and paper may change size due to atmospheric conditions; there- fore, scale and proportions may not be true on plots of this map. For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center Denver, CO 80225. 1-888-ASK-USGS Digital files available on World Wide Web at http://geopubs.wr.usgs.gov Base from U.S. Geological Survey, 1956; limited revisions, 1984 Universal Transverse Mercator, zone 5 U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY CONTOUR INTERVAL 200 FEET NATIONAL GEODETIC VERTICAL DATUM OF 1929 1984 MAGNETIC DECLINATION AT SOUTH EDGE OF SHEET VARIES FROM 25 TO 27 EAST ad sd io 1 sd tr i io 1 sd io 1 s sd so s al al s io 1A al 1 sd al 1 gr sd al io 1A io si al al 1 al 1 ? sa f i f i sd fd l io si s (sd) si sd 2 s so l s id 1 s io 1 sd io fd s s s s al 1 s l f i fd s io 1A sd sd sd fd fd io 1 m (sd) s fd c c sd 2 c sd sd (sd) (ad) s/sd al 1 sd f i io 1 f sa al 1 s sd sd so sd s (ad) s (sd) d? c (sd) sa? (sd) ad sd sd gr sd f m (ad) (gr) sd so gr so al 1 so s b (ad) s s/sd l l (ad)? s so sd c io 1 ? ad? sgl/sd sd sd sgl? m so s al s c al td C2 sd c (ad) ad? l? us tg B2 tr i c gr/sd al 1 l? tg B3 so ad? c c sd ao al 1 s ad s tg B2 tg B2 ad io? s c sgl io ad c ad sgl so s m td A2 c s tg B1 m gr ad m s tg B2 ad s/al ad ad c f ad tg B3 gr gr? td A2 ao al 1 f s (sd)? sgl? td A2 (ad)? s s ad? s ad? io 1 ? td C2 sgl/sd? si us c sd c c s tg B2 c si s/gr? si (ad)? us ao so? ad s sd/sgl? td A3 s tg B1 td A1 c (ad) c sd ao so m c us/ad? d? us s td A1 c f s si/B m al td A3 td A3 us s s td A3 us/ad? td A2 td A1 c td u /agl s s c s al s c m ad ad c s s si/B f s s s sd ao? so s/l c td A1 ad? s si agl/ad? l? s/l s us f l? io l? sgl l? s l? l/ao? al us s c us tg u ? s/io us s l/B s s s f s s ad? us s/l c gr td u si s c sgl s f c s/l us f s us c sgl? s sgl s s c m ad sgl al 1 s al 1 s ao? tg u us sgl (us) al 1 ad c s td u sgl/ad ao? td C3 al 1 s ad s agl/ad s s al c c s td C3 s td C3 al 1 sgl agl/ad sgl/ad al 1 ao f i c sgl c sgl m sgl td C3 sgl c s (s) al 1 ad? al 1 s sgl s m (s) c ad sgl tg D3 tg D1 (us) Tgmd al 1 sgl (us) ad s al 1 ad s c s (s) s c m sgl c c c (us) s f sa al s s f sa s s sgl c (s) tg DH Tgmd s sgl (s) f sgl s c s s s c al s c us td D3 s/al f sa Tgmd agl s f sa ad? sgl c us gl? s sgl? (c) sgl? s Tgmd c sa+gr s m agl? al 1 s Tgmd? us s s s al 1 Tgmd? (c) s Tgmd us s us s sgl m al 1 al s us td u s sgl? si al 1 (us) s sgl sgl? al sa s us td u sgl al sgl agl us sgl gr s sgl sgl/Tgmd Tgmd sgl us sgl s us s s agl Tgmd s agl? si s s s sgl l sgl s al s sgl (c) c sgl s ds 1 fl si ds 2 m gr? (c) ds 1 (c) s ls? si b? al s (us) s (c) ds 1 s s ds 1 l s us/Tgr (c) f ls? l? us (c) si s s b ds 1 Tgr ls? s al sa s us sgl s sgl? Tgr? s al si/al s si us s/al (c) Tgr? b? us (s)? b l 1 us s (c) fl l 1 ? s si si/al s/al (s)? d? si sgl (c) us si si s agl Tgr d? s s us si (c) us agl si/al agl (s)? s s us agl Tgr? s (s)? s s s/f i us si? si/al us si (c) si us gr Tgr us us si/al s gr gr si/al f i s c agl (c) si us s f i (us) us (ad) sgl/ad s ad fl s fl al 1 sd al s sd al id 1A id 1A id 1 id 1 l s sd sd al s io 1 ? al s l io 1A sd (sd) so tg B2 sgl/sd? s/so sd m us sgl? m s m/td C3 s al td C2 sgl? al 1 s io td C2 m al 1 ad? s sd/sgl io l s s al 1 s al 1 fd d? td C2 td C1 f ad? d? ad ak td C2 us us ad (ad) al 1 m/td C2 ad ad? sgl/ao sgl s us td u sgl? ad al 1 td C3 al s us gr al 1 io sgl al 1 sgl? gr/sa al 1 m/td C2 m td C3 sgl al 1 sgl m ad m sgl us m ad agl/ad ad? ad? Tgmd? sa? Tgmd al 1 sgl ad s tg DH tg DH tg D3 s al sa sa? s s sgl (us) m c us s sgl? ad? m c c (c) agl (c) c us m si Tgmd? s us/Tgmd? si sgl s gr? al (c) agl/Tgmd s Tgmd? m s si s si s us s al sgl/Tgmd si us agl s al sa s us s sgl agl s sgl m l 1 sgl agl (us) (us) us us s al s l l 2 us us us us sgl al s ds 1 fl ds l 1 us s us us sgl sgl agl? s sgl (us) us sgl us (c) (c) agl s l 1 ? si us s s s us (us) si us si si/al al 2 al (ad) c s ao c f ad s al ad S M al al al al 2 al 2 al 2 al 2 al 2 al 2 al rg i ? ls? rg i fd fd (sd)? io 1 f sd c so ls rg i rg i rg i rg i rg a sa sa l 1 s al 1 Tgmd? al 1 c ik f rg i s ad gr gr gr f f f f gr f f f al 2 b gr f f T ao gr sd gr sgl/ad (d) s gr td A2 td A2 td u sd (sd) (c) f LIST OF MAP UNITS [See pamphlet for detailed descriptions. Units queried where uncertain.] FAN DEPOSITS Fan deposits—Range from coarse gravel (mountain valleys) to gravelly sand and silt (Koyukuk basin) Inactive fan deposits Sandy fan deposits—Dominantly sand- to granule-sized Fan-delta deposits—Alluvial-fan deposits that grade distally into lacustrine beds ALLUVIUM Alluvium, undivided—Coarse gravel to sandy fine gravel and gravelly sand. Locally includes fan and low terrace deposits too small to map separately Fine-grained alluvium—Along slow-moving streams Sandy alluvium—Along slow-moving streams Modern alluvium—Gravel and sandy gravel; generally unvegetated Low alluvial terrace deposits—Gravel and sandy gravel, mantled with thin silt, sand, turf, and peat Gravel deposits, other—Gravelly erosion remnants of obscure composition and origin Quartzose gravel of inferred Tertiary age—Rounded quartz pebbles and small cobbles in nearly pure quartz sand TERRACE DEPOSITS Terrace deposit—Alluvial gravel; commonly intergrading or mantled with fluvial, deltaic, lacustrine, or organic deposits Terrace gravel—Alluvial gravel, sandy gravel, and floodplain deposits; commonly mantled by loess, muskeg, and thaw-lake sediments A. Terrace deposits along Henshaw Creek Terrace deposit, low-level (late Pleistocene)—Alluvial gravel and sandy gravel, forming terraces 8-14 m high that decrease in height downstream Terrace deposit, intermediate-level (middle Pleistocene)—Gravel and finer sediments, forming terraces up to 35 m high that decrease in height downvalley Terrace deposit, high-level (early Pleistocene)—Gravel and finer sediments, forming terraces up to 75 m high that decrease in height downvalley B. Terrace deposits along Jim River Terrace gravel, low-level (late Pleistocene)—Gravel and sandy gravel, forming terrace remnant 2-3 m above river Terrace gravel, intermediate-level (late middle Pleistocene)—Gravel and sandy gravel, forming terraces 25-30 m high Terrace gravel, high-level (early middle Pleistocene)—Gravel and sandy gravel, with thick (5 m or more) silt cover, forming dissected terraces about 50 m high C. Terrace deposits along Koyukuk River (upvalley from Allakaket) and South Fork Koyukuk River Terrace deposit, low-level (late Pleistocene)—Sandy gravel, with some finer-grained deposits; muskeg cover locally thick and continuous. Forms terraces 5-10 m high that decline in height downvalley Terrace deposit, intermediate-level (late middle Pleistocene)—Terrace deposits about 20-25 m high with muskeg cover locally thick and continuous Terrace deposit, high-level (middle Pleistocene)—Terrace deposits about 40 m high along South Fork D. Terrace deposits along Koyukuk River below Allakaket Terrace gravel, low-level (late Pleistocene)—Alluvial gravel and sandy gravel, forming terraces 8-10 m high Terrace deposit, low-level (late Pleistocene)—Sandy gravel, with some finer-grained deposits. Near mouth of Kanuti River Terrace gravel, high-level (early Pleistocene)—Alluvial gravel with silt cover, forming terrace remnants 50-60 m high Terrace gravel, highest-level (early Pleistocene?)—Oxidized gravel capped by thick loess. Forms terrace remnants up to 120 m above Koyukuk River al al s al sa al 1 al 2 gr Tgr f i f sa fd tg u td u td C3 tg B3 tg B2 tg B1 tg D3 tg D1 tg DH td A3 td A2 td A1 COLLUVIAL DEPOSITS Colluvium, undivided—Mixed solifluction deposits and talus rubble Solifluction deposits—Poorly sorted stony silt and organic silt Flow deposits—Lobes of angular rock rubble in abundant silty matrix Landslide deposits—Angular rubble below detachment scars and slide tracks Rock-glacier deposits, active—Lobes of coarse angular rock debris with matrix of ice-rich silt and fine rubble Rock-glacier deposits, inactive—Coarse angular rock debris lacking interstitial ice. Surfaces weathered and partly vegetated Talus rubble, inactive—Angular rock debris along lower walls of mountain valleys. Surfaces weathered and partly vegetated SAND, SILT AND ORGANIC (MUSKEG) DEPOSITS Dune sand—Fine to medium sand, commonly forming parabolic ridges Dune sand, younger and older components—Where partly reactivated by wind Sand deposits—Sand with granules and sparse small pebbles; in grus-filled basins Ice-rich silt deposits—Silt, commonly with ice-wedge polygons, in depressions and along valley centers Upland silt deposits—Silt, organic silt, and slightly stony silt; commonly grades downslope into solifluction deposits Muskeg—Organic deposits more than 1-2 m thick where drainage restricted LACUSTRINE AND GLACIOLACUSTRINE DEPOSITS Beach deposits—Sand and platy fine gravel; locally shoved into ridges Lacustrine deposits—Fine sediments, grading into sand and gravel near former shorelines and river mouths Lacustrine deposits, low-level (late to middle Pleistocene)—Stratified silt and related deposits. Overlain by muskeg with abundant lakes Lacustrine deposits, high-level (early Pleistocene)—Stratified silt and related deposits forming poorly drained surfaces above bluffs 30 m high Glacial-lake deposits, undivided—Stratified silty deposits of uncertain age Glacial-lake deposits of Sagavanirktok River age (middle Pleistocene)— Fine sediments grading into sand to fine gravel near former stream mouths Glacial-lake deposits of Anaktuvuk River age (early Pleistocene)—Stratified stony silt, forming erosion remnants that generally bear thick cover of ice- rich silt with numerous thaw ponds OTHER GLACIAL DEPOSITS Drift, undivided—Glacial deposits of uncertain age Itkillik glaciation (late Pleistocene) Drift of Itkillik Phase I—Compact bouldery till with local ice-contact sand and gravel Drift of Itkillik Phase IA—Outermost moraine and associated drift of Itkillik complex Kame and kame-terrace deposits—Unusually thick and extensive water- washed sand and gravel Outwash of Itkillik age, undivided—Valley trains of sandy gravel Outwash of Itkillik Phase I—Sandy gravel associated with drift of Itkillik I age Outwash of Itkillik Phase IA—Outwash train that originates at moraine of Itkillik IA age c s fl ls rg a rg i tr i ds ds 2 ds 1 sa si us gl sgl agl Sagavanirktok River glaciation (middle Pleistocene) Drift of Sagavanirktok River age—Bouldery till and ice-contact gravel, generally covered by thick loess, solifluction, and muskeg deposits. Weathered gravel and erratic boulders exposed on some ridges and knolls Drift of Sagavanirktok River late phase—Till and ice-contact deposits Outwash of Sagavanirktok River age—Sandy gravel associated with end moraines of Sagavanirktok River age Anaktuvuk River glaciation (early Pleistocene) Drift of Anaktuvuk River age—Bouldery till, with some coarse gravel Kame terrace(?)—Linear gravel-rich deposit Outwash of Anaktuvuk River age—Gravel and sandy gravel, associated with moraines of Anaktuvuk River age Gunsight Mountain glaciation (Tertiary?) Drift of Gunsight Mountain age—Till and ice-contact deposits, forming isolated erosion remnants MAP SYMBOLS Contact—Dashed where approximately located or inferred Fault—Expressed in Quaternary sediments. Dashed where approximately located or inferred. Arrows indicate direction of lateral motion Drainage channel—Abandoned or underfit Crest of morainal ridge Headwall scarp of debris flow Direction of glacier flow across topographic divide Direction of ice movement or meltwater drainage— Associated with ice- scoured bedrock Former glacial-lake outlet or drainage diversion U-shaped pass—Where glacier crossed topographic divide Spring Pingo Bedrock, undifferentiated Bedrock—Exposed along canyon walls or margin of river terrace Near-surface bedrock—Generally covered by 1-2 m of sod, peat, loess, solifluction deposits, and rock debris; usually completely vegetated Pediments—North and east of Sithylemenkat Lake. Bear thin colluvial cover Altiplanation terrace Surface and subsurface lacustrine deposits Heavily eroded surficial unit Lake—M, Minnkokut; S, Sithylemenkat; T, Todatonten d id 1 ik id 1A sd sd 2 io io 1 io 1A td C1 td C2 m b l ak ad Tgmd so ao l 2 l 1 td D3 f ? CORRELATION OF MAP UNITS al 2 c s sa si al 1 ds 2 ds ds 1 td u tg u td A3 tg B3 td C3 tg D3 us l io l 2 gl io 1 ik io 1A td A2 tg B2 b sgl sd sd 2 so tg B1 td A1 tg D1 l 1 agl ad ao ak tg DH Tgmd Tgr rg a rg i fd tr i d id 1 id 1A td C2 td C1 Fan deposits Alluvium Terrace deposits Colluvial deposits Sand, silt, and organic deposits Lacustrine and glaciolacustrine deposits Other glacial deposits ls fl Main phase Late phase Sagavanirktok River glaciation Phase I Phase II Gunsight Mountain glaciation Anaktuvuk River glaciation Itkillik glaciation Pleistocene Holocene TERTIARY(?) QUATERNARY A B C D ? ? ? ? ? ? gr m ? ? ? al f i f sa , al s , and al sa (textural facies of units f and al) are not shown on correlation chart U M TERRACE DEPOSIT COLUMNS U. Age unassigned A. Henshaw Creek B. Jim River C. Koyukuk River + South Fork Koyukuk River D. Koyukuk River west of Allakaket td D3