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1 LO'M)" 1m0' 1 - - EXPLANATON -,* CkEw llmR lodllW~Hon , ./ Cbakrsga dIvMs Dashal~krdlcats appmximn locatloris 0 25 50 KILOMEPERS I ' A I I I 160'00' 1 BBWO' SO KlLmETERS -.-.-.rm Symbols same as map A Figure 12.-Palqeagraphy of WF Noatak Valley hlng the It' ~latfon (AJ and subsequent walker Lake Glaciation (,"' 22
' Noatak Vdley (fig. 129. This ice lobe extended eastward up the Noatak to terminate about 30 km northwest of the mouth of the Cutler River; a smaller glacier extended about 100 km down the upper Noatak Valley and terminated 65 km east of the Cutler River. Only the extreme southeastern part of the Cut- ler drainage system was glaciated at this time, and no glaciers formed in the low mountalns north of the Noatak Valley. The proglacial lake dammed by the De Long Mountains ice tongue rose to about 35g m Edti- tude and covered an.araa of about 700 km ; it was confined to the center of the Noatak Valley and inset within ground-moraine and lake deposits dating from the earlier glaciation. The lake drained southward into the lower course of the Nmtak Vdey via a spillway across a northern outlier of the Baird Mountains. Glaciolacustrine sediment exposed In bluffs dong the Noatak Valley consists of weakly bedded silt contain- ing dropstones that unconformably overlies compact peat and organic silt. The earlier and later intervals of glacial expan- sion and lake formation in the Noatak Valley can be correlated, respectively, with the ItkiJlik Glaciation of the central Brooks Range, as defined by Detterman end others (19581, and with the Walker Lake Ghclation of the Kobuk VaIIey (Fernald, 1964). Recent radio- carbn doting has shown that the Walker Lake Glacia- tion began about 24,000 yl' B.P. and ended by 11,800 yr B.P. or shortly thereafter (Hamilton, 1982). The Itkillik Glaciation was earlier than the maximum time range conventional radiocarbon dating (approx 55,000 C yr), and its exact age is uncertain. Correl- ative deposits in the Alaska Range are inferred to be early Wisconsinan (Weber and others, 1981), and the absence of soils, weathering profiles, or interglacial fossils between deposits of Itkillik and Walker Lake age in the Brooks Range appears to support this age assignment. The presence of ancient proglacial lakes in the upper Noatak Valley has important environmental implications. Silt- and clay-rich lacustrine and deltaic sediment is widespread in the valley center, and fine- grained slack-water deposits extend far up into -la- ciated tributary valleys. This sediment is poorly dralned, frost susceptible, and commonly ice riehj It is subject to failure along river bluffs and to frost heave, thaw settlement, and thaw-lake formation across the valley flwr. Large stream ic- occur around the perimeter of the former lake basin in places where permeable stream gravel grades laterally into ilner gained lacustrine and dslhic deposits. Late Pleistocene environments throughout much of the Brooks Ehnge could have been strongly affected by the roglacid lakes. Although outlets from the earlier !450 rn) lake stage arc uncataln st present, these may have included flows across lightly gIaciated passes into the Hunt River drainage system of the Kobuk Valley or into the lower Noatak Valley (fig. 12A). Outburst floods resulting from breaching of the ice dam west of the Cutler River may have occurred intermittently during the maximum glacial phases, and such floods almost certainly took place when the ice darn was smaller during growth and recession toward the beginning and end of each glaciation. Such floods would have greatly affected the lower Noatak Valley and should have created shck-water deposits within its 2 unglaeiated tributaries (for example, Waitt, 19801, as well as largescale alluvial deposits and erosional forms along the main valley. me large lake of Itkillik age should have been an important moisture source during summer and fall for mountains near the heads of the Noatak, Alatna, and Kobuk Valleys that Lie along the paths of storm tracks moving inland from the cast. Presence of the lake may account in part for extensive ItkilIik-age glaciation in the western Brooks Range. In view of mounting evidence for late Pleisto- cene aridity in northern Alaska and the Yukon Terrlto- ry (Cwynar and Ritchie, 1980; Carter, 1981; Hamilton, 19821, large proglacial lakes in the Noatak Valley could aka have had a major influence on the distribution of large grazing mammals and their predators, possibly including early man. The Lakes not only could have provided a local water source in a generally arid region but also might have induced locally higher rainfall and locally milder temperatures during late summer and early autumn. Access into the upper Noatak lake basin would have been readily accomplished via unghciated passes to the north and via additional passes to the south during Walker Lnke time. REFERENCES CITED Certer, t. D., lD8i, A plelstocene sand sea on the Alaskan Arctic Coastal Pl8ln: Science, V. 211, no. 4480, p. 381-383. Coulter H. W., Hopkins, D- M., KarkCrorn, T. N. V., P ~ , T . L., Wahrhaftig, Clyde, and Williams, J. R., cornpuets, 1965, Map showing extent of glaclatlons in Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Series Map I- 415, scale 1:2,500,000. Cwynar, L. C., and Ritchie, J. C., 1980, Arctic steppb tundra: A Ylon perspective: Sclence, v. 208, no. 4450, p. 1375-1377. Detterrnan, R. L., Bowsher, A. L., and Dub, 3. T., Jr., 1958, Glaciation m the Arctic dope of the b k s Range, northern Alaska: Arctic, v. 11, no. 1, p. 43-61. Pemald, A. T., 1964, Surficid geology of the central Kobuk River Valley, northwestern Alaska: U.S. Geological Survey Bulletin 1181-K, p. Kl-K31. Hamilton, T. D., 1980, Surficial geologic map of the Killik River quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MP- 1834, scale 1:250,000. -1981, Surficial geologic map of the Sumrey Pass quadrangle, Mesh: U.S. Geological Survey Miscellaneous Field Studles Map MP-1920, scale 3:250,000. 4982, A lete Pleistocene glactal chmology fop the southern Bmks bnge: Stratigraphic record and reginal significance: Geological hiety of America Bulletin, v. 93, no. 8, p. 6853-6864. Wdtt, R. B., Jr., 1980, About fatty last~lacid lake Miswule j&ulhlaups through southern Washington: Juurnal of Geology, v. 88, no. 6, p. 653-679. Weber, P. R, Hamilton, T. D., Hopkins, D. M., Repenning, C. A., and Haas, Herbert, 1981, Canyon Creek: A Late Pleistocene vertebrate locality in Interlor Alaska: Quaternary Research, v. 16, no. 2, p, 187-180.
Page 1 and 2: n Alas Accompli: ' I.S. GE OLOGI CA
Page 3 and 4: I CONTENTS Page A bst raet ........
Page 5 and 6: -- --A I ALASEU i nued rral expluru
Page 7 and 8: ........ igure .JB. ;5~ercn map ox
Page 9 and 10: . , ".,k a. ,.e ,\a 1 y U11 IIIUUII
Page 11: THE UNITED STATES GEOLOGICAL SURVEY
Page 15 and 16: ~ t I r n t S i m ~ ~ Alarr a ~ man
Page 17 and 18: I -1977, RelImlnary documentat!on l
Page 19 and 20: I I MaCenn, W. R., Perez, 0. J., an
Page 21 and 22: were deslgned to impMve the accurac
Page 23 and 24: Noatak Sandstom and is overlaln con
Page 25 and 26: I (Nilsen and others, 1981a); (2) f
Page 27 and 28: I that contains the Upper Devonian
Page 29 and 30: who found Westeqaardodina sp., posb
Page 31: Table 2 lists the means rtnd for th
Page 35 and 36: 3 EUMN OF MAP UNITS WAmWARY OUAERNA
Page 37 and 38: -om displacement of the cc tween th
Page 39 and 40: I US I Surlicial dcnrrua,ts [~dater
Page 41 and 42: I Plafker, George, Hudson, Travis,
Page 43 and 44: !omlensed iring vapors generated by
Page 45 and 46: and the thinning. -upward cycles .,
Page 47 and 48: Kellum, L. B., Devless, S. N., and
Page 49 and 50: 1912 sample (a mediumwey pumice blo
Page 51 and 52: various Utholagic units present Thu
Page 53 and 54: fault, and Its depositional basemen
Page 55 and 56: suggested by coplanar foUaticm and
Page 57 and 58: 1 slgnlficarrtly more umnlum (73&1,
Page 59 and 60: ecrSigtallized catadastic matrix of
Page 61 and 62: analyzed to determine whether Immob
Page 63 and 64: are tgplcd of both ocean-floor basa
Page 65 and 66: & Fclsic in~rutirt rucks 0 Eio~ite
Page 67 and 68: are Lrdlcated by coexisting @&ite+q
Page 69 and 70: (Mg3.09 pe2+ 0.69 pe 0.~1~0.01~~0.9
Page 71 and 72: westward into a narrow band that ex
Page 73 and 74: EXF'lANATIOW 66600' Contan-Apprnimn
Page 75 and 76: ! few fold closures are preserved.
Page 77 and 78: even thickness and conform to irreg
Page 79 and 80: (Alnus ap.), heaths (Ericaceae, + E
Page 81 and 82: terrane extends at least 300 krn to
Page 83 and 84:
Table 19.--6tneral petrography of M
Page 85 and 86:
were measured on 8 12-in. mass spec
Page 87 and 88:
Thin lenses of cabonate packtone to
Page 89 and 90:
The cantwell(?) Pormation south of
Page 91 and 92:
in the 18 lava flows b thermoremane
Page 93 and 94:
Upper Cretaceous shale in contact w
Page 95 and 96:
Gran tz, Arthur, 1960, Generalized
Page 97 and 98:
at 15 to 20 percent. Primary Inolus
Page 99 and 100:
addition, this factor generally def
Page 101 and 102:
Joreskog, K. G., Klovan, J. E., and
Page 103 and 104:
Mineral qItWation end r ~ k t k W e
Page 105 and 106:
1 "~_liO-/ 200 1000 B roo C E % A B
Page 107 and 108:
Smaller placer mines ere active on
Page 109 and 110:
Figme 62.-Plant fassils from the co
Page 111 and 112:
Hallam, Anthony, 1975, Alfred Wegen
Page 113 and 114:
u ALASKA Figure 65.--Sketch map of
Page 115 and 116:
F ' i a?.-Intertidal bluffs compose
Page 117 and 118:
C-s - - Figure 70.-Products of eros
Page 119 and 120:
curve is based indicates that 6.1 c
Page 121 and 122:
sampled is related to widespread ma
Page 123 and 124:
marble is alsa locally present In t
Page 125 and 126:
Bedding in the conglomerate ranges
Page 127 and 128:
1 purpose of this study wes to dete
Page 129 and 130:
The secona k~~-~ri?tation mmes that
Page 131 and 132:
epizonb'l granitic Miss, mixed with
Page 133 and 134:
40 40 Forbes, R. B., and Engels, J.
Page 135 and 136:
foliated and inequigranular end con
Page 137 and 138:
I I thy euheclra. Sphene anhedra an
Page 139 and 140:
Quartz Alkali feldspar Plagioclase
Page 141 and 142:
F'@m 85.--Sketch map of Juneau area
Page 143 and 144:
HoUister, L. 8, 1966, Garnet zoning
Page 145 and 146:
! ~ bI8oO, (IN PERMIL) ~lqp~e 87.-8
Page 147 and 148:
Figure 90.-Offshore ereas discussed
Page 149 and 150:
Preliminerg analpsis of miemfauna f
Page 151 and 152:
Survey tn Alaekai AccompUshments hh
Page 153 and 154:
Gecllogical Survey Open-File Report
Page 155 and 156:
I provenance, and tectonia sIgnific
Page 157 and 158:
Keith, T. E. C, Barnes, Ivan, afrd
Page 159 and 160:
Open-Flle Report 8P811C, 19 p. + 2
Page 161 and 162:
United States Qeological Survey in
Page 163 and 164:
, ,. nldslra poblisbe!d by Prior, D
Page 165 and 166:
60, Alaska: Offshore Technology Con
Page 167:
Author Index [Page number underscor
Page 170 and 171:
Parks. Bruce ......................
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