Quaternary Geology and Permafrost Along the Richardson and Glen Highways Between Fairbanks and Anchorage, Alaska: Fairbanks to Anchorage, Alaska July 1-7, 1989

60 Pages·2000·4.48 MB·English

FRONTISPIECE. SolifluctionlobesatheadwatersofeasttributaryofNomeCreek, 75 mi
(128 Ian) SWofCircle,Alaska. Aerialview towardNE. GlaciatedMt. Prindle [5286ft
(1800m)] inrightbackgroundon skyline. (Photograph 2694 byTroy L. Pewe, July 9, 1968).
Quaternary Geology and Pennafrost
Along the Richardson and Glen
Highways Between Fairbanks
and Anchorage, Alaska
Fairbanks to Anchorage, Alaska
July 1-7, 1989
Field Trip Guidebook T102
Edited by:
Troy L. Pewe Richard D. Reger
Contributors:
OscarJ. Ferrians Donald R. Nichols Troy L. Pewe
Richard D. Reger Randall G. Updike
John A. Westgate John R. Williams
American Geophysical Union, Washington, D.C.
Copyright 1989 American Geophysical Union
2000 Florida Ave., N.W., Washington, D.C. 20009
ISBN: 0-87590-603-6
Printed in the United States of America
COVERPHOTOORAPH. Placergold-miningdredge 15kmwestofFairbanks,Alaskain 1947. Dredgefloats
in apondanddigs gold-bearing gravelatfarleft. Goldisextractedmechanicallyonthedredge. Gravel tailings
aredroppedattheotherendofthedredgeand stackedlike giant,upturnedcoins. Dredgeismininginthe
Pleistocene/PlioceneCrippleGravel betweenEsterandCrippleCreek. SeventymofFairbanksLoesswas
removedto uncoverthe gravel. In thebackgroundisacliffofunremovedFairbanksLoess62mhightermedthe
EsterIslandSection. ThetypelocalityoftheEsterAshBed(840ka) liesnearthe baseoftheloesscliff. Large
scaledredge goldminingendedintheFairbanks areaJune30, 1965. Thisdredge stillfloats todayin apond
nearby this locality. (PhotographPK 693 byTroyL. Pewe, July 12, 1947).
TABLE OF CONTENTS
Page
Introduction 1
Fairbanks Area 3
Pewe,
TroyL. RichardD. Reger, andJohnA. Westgate
Middle Tanana Valley 17
Pewe
TroyL. andRichardD. Reger
Delta River Area 25
Pewe
TroyL. andRichardD. Reger
Copper River Area 39
OscarJ. Ferrians, Jr, DonaldR. Nichols, andJohn R. Williams
Upper Cook Inlet Region and Matanuska Valley 45
RichardD. RegerandRandall ·0.Updike
vii
Leaders:
Pewe
Troy L.
Department of Geology
Arizona State University
Tempe, AZ 85281-1404
Richard D. Reger
Division of Geological and Geophysical Surveys
3700 Airport Way
Fairbanks, AK 99709
Associate Leaders:
John Westgate
Department of Geology
University of Toronto
Scarborough Campus
Scarborough, Ontario
M1C 1A4 CANADA
Oscar Ferrians
U.S. Geological Survey
4200 University Drive
Anchorage, AK 99508
ix
INTRODUCTION
General statement R.G. Updike, the original authors.
James C. Walters provided recent information on
Permafrost and marine, fluvial, lacustrine, glacial, frost-sorted features in the vicinity of the Denali
eolian, andperiglacial deposits ofQuaternary age that Highway. The authors appreciate the efficient
are widespread in the central and southern parts of cartographic support provided by Susan Selkirk
Alaska are forming today. Glaciers are common in (ArizonaStateUniversity),DuncanHickmott (DOGS),
mountainous areas, andthe forces ofglacialactionthat Dave Vogel (DOGS) and Karen Pearson (DOGS).
formerly shaped much ofthe world's land area can be Cheri Daniels (DOOS) edited the 1983 guidebook.
directlyobservedtodayinsouthernAlaska. Geological Peter Eagan, Manager, Alaska Gold Company,
processes active incoldregions---periglacialprocesses Fairbanks, andWalterWiggerofEvaCreekProperties,
suchas solifluction,cryoplanation,andthe fonnationof kindly grantedpermission to allow participants ofthe
permafrost---are known throughout much ofthe area. fieldexcursionontheirrespectiveproperties.
Dust is blown from active valley trains and outwash References usedin compilingresumes androadlogs
fans andisdepositedas loessontheadjacentterrain. are listed in the general bibliography and in
Five major areas are considered (fig. 1): a) the bibliographies at the end of individual sections.
Fairbanks area,b) themiddleTananaRivervalley, References,are generallynotinsertedin the text,except
c) the DeltaRiver areaofthe AlaskaRange, including wherecontroversialpoints arediscussed.
theeasternDenaliHighway,d) theCopperRiverBasin, All radiocarbon dates are given in years before
and e) the upper Cook Inlet region and Matanuska present(B.P.) with appropriatelaboratorynumbers.
Valley. The Fairbanks area and the middle Tanana
River valley is typical of the unglaciated interior of
Alaska, with its extensive eolian deposits, widespread
perennially frozen ground, and silt-choked glacial
streamsnearmajormoraines.
The Delta River area ofthe Alaska Range and the
DenaliHighwayarecharacterizedbynumerous glaciers 9 5,0 Miles
anddeposits thatrecordmoreextensiveglaciationinthe ~O Kilometers
past. The CopperRiverBasinhas aninterestingrecord
of alternating glacial and lacustrine deposits. Lake
deposits are perennially frozen and present serious
problemstoutilizationbyman. In the upperCookInlet
regionandMatanuskaValley---includingtheMatanuska
Glacier---extensiveevidenceofmultiple glaciation and
numerous landslides generated by the Good Friday
EarthquakeofMarch27,1964,arepresent. TheTrans
AlaskaPipelines Systemparallels the highway for 300
mi (483 km) through the four northernmost areas
N
coveredbythis guidebook.
r
Organization and Acknowledgements
Theoverallorganizersandeditorsofthis guidebook
and field excursion are Troy L. Pewe and Richard D.
Reger. The section on the Fairbanks area is modified
and greatly updatedfrom the 1965 "Central andSouth
Central Alaska Guidebook F" for the Seventh INQUA
editedby T.L. Pewee Troy L. Pewe, RichardD. Reger
and John H. Westgate are responsible for this section.
Theremainingfour sections are greatlycondensedfrom
an extensive guidebook entitled, "Richardson and
Glenn Highways: Ouidebook to Permafrost and
Quaternary Geology" prepared for the Fourth
International Conference on Permafrost; 1983, edited
byT.L. Pewe andRichardD. Reger. Figure 1. - Index map showing field trip route from
The sectionontheCopperRiverBasinis updatedby FairbankstoAnchorage, Alaska.
the original authors, O.J. Ferrians, Jr., D.R. Nichols,
andJ.R. Williams. Thesectiononthe upperCookInlet
region andMatanuskaValley is updated by Reger and
T102:
scale 1:500,000, 1sheet.
SELECTED REFERENCES Pewe T.L., Ferrians, O.J., Jr., Karlstrom, T.N.V.,
Nichols, D.R., 1965, Guidebook for Field
Coulter, H.W., Hopkins, D.M., Karlstrom, T.N.V., Conference F, central and south-central Alaska,
Pewe, T.L., Wahrhaftig, C., and Williams, J.R., International Association for Quaternary Research,
1965, Extent of glaciations in Alaska: U.S. 7th Congress, Fairbanks, 1965: Lincoln, Nebraska
Geological Survey Miscellaneous Geologic Academy of Science, 141 p. (reprinted 1977,
Investigations Map1-415, scale 1:2,500,000, Alaska Division of Geological and Geophysical
1sheet. Surveys).
Mertie, J.B., Jr., 1937, The Yukon-Tanana region, Pewe, T.L., and Reger, R.D., 1972, Modern and
Alaska: U.S. Geological Survey Bulletin 872, Wisconsinan snowlines in Alaska: International
276 p. Geological Congress, 24th, Montreal, 1972,
Pewe, T.L., 1958, Geology of the Fairbanks (D-2) Proceedings, v. 12, p. 187-197.
Quadrangle: U.S. Geological Survey Geological Pewe, T.L. and Reger, R.D., 1983, (eds.) Guidebook
Quadrangle Map GQ-110, scale 1:63,360, 1sheet. to permafrost and Quaternary geology along the
Pewe, T.L., 1969, The periglacial environment, past Richardson and Glenn Highways between
andpresent: Montreal, McGill-Queen's University Fairbanks and Anchorage, Alaska: AlaskaDivision
Press, 487 p. of Geological and Geophysical Surveys Guide
Pewe, T.L., 1975 Quaternary geology ofAlaska: U.S. book 1, 263 p.
Geological SurveyProfessionalPaper835, 145p. Pewe, T.L., Wahrhaftig, Clyde, and Weber, F.R.,
Pewe, T.L.,1982, Geologic hazards of the Fairbanks 1966, Geologic map ofthe Fairbanks Quadrangle,
area, Alaska: Alaska Division of Geological and Alaska: U.S. Geological Survey Miscellaneous
Geophysical Surveys SpecialReport 15, 109p. Geologic Investigations Map 1-455, scale
Pewe, T.L., Burbank, Lawrence, and Mayo, L.R., 1:250,000, 1sheet.
1967, Multiple glaciation of the Yukon-Tanana Wahrhaftig, Clyde, 1965, Physiographic divisions of
Upland, Alaska: U.S. Geological Survey Alaska: U.S. Geological Survey Professional
Miscellaneous Geologic Investigations Map 1-507, Paper482, 52 p.
T102: 2
FAIRBANKS AREA
Troy L. Pewe1, Richard D. Reger2, and John A. Westgate3
RESUME OF QUATERNARY GEOLOGY AND Summers are short, sunlit, and \varm and maximum
PERMAFROST temperaturesoftenexceed85°F (29.4°C).
Between 1930 and 1980, the mean annual
temperature at Fairbanks was 25.7°F (-3.5°C); the
Location and physiography lowest official air temperature (-62°F or -52.2°C) was
recordedinDecember 1961,andthe highestofficial air
Fairbanks, at433 ft (132 m) elevation, is locatedat temperature (96°F or 35.6°C) was recorded in June
65°N latitude about 100 mi (185 km) south of the 1969.
Arctic Circle astraddle the boundary between Tanana About30percentofthe annual precipitation falls as
Lowland (to the south) and Yukon-TananaUpland (to snow, which normally covers the ground from middle
the north) (Wahrhaftig, 1965). Ridge crests in the to late October through mid-April. Total snowfall
vicinity reach elevations of 1,250 to 1,800 ft (380 to variesconsiderablyfromyeartoyearbutaveragesclose
550 m) andreliefranges from 600 to 1,300ft (183 to to 70 in. (1.78 m).
397 m). An extensive apron of coalescing piedmont
alluvialfans slopes northwardfrom the foothills ofthe Permafrost
centralAlaskaRangetotheflo<XlplainofTananaRiver.
Physiographically,theFairbanks areais divisiblein Fairbanks is locatedin the discontinuous permafrost
to loess-covered bedrock hills, lower hillslopes and zone, where perennially frozen ground is
creek-valley bottoms, organic-silt lowlands, and flood relatively warmand sensitive to disturbance. Lowland
plains adjacent to Chena and Tanana Rivers (fig. 2). sites are underlain by permafrost, which at the level of
Windblown silt ranges in thickness from a few inches zeroamplitude, generallyrangesintemperaturebetween
(cm) on hill tops and ridge crests several miles (km) 31.9° and 32°F (-0.6° and O°C), although temperatures
north of Tanana River up to about 200 ft (60 m) on as lowas 26.1OF (-3.3°C) have been measuredin local
hillsides near Tanana River flood plai~, which is the areas with especially coldmicroclimates (RaymondA.
source of this material (Pewe, 1951, 1955, 1968). Kreig, oralcommunication, June 27,1983).
Fluvialfans oforganic silt (retransportedloess) spread In general, approximately half of the upland in the
from gullies in loess on middle and upper slopes, vicinity ofFairbanks is underlain by permafrost, most
coalescing and combining with airfall silt to build of which is ice rich (Pewe, 1958a; Pewe and Bell,
complexloess fills up to 300ft (100 m) thickin valley 1974). However, the extent of permafrost varies
bottoms. considerably, depending on site factors such as
Fairbanks is built on the combined flood plains of geologic materials, vegetation cover, slope angle and
Chena River and Tanana River. This aggradational aspect, andhistory ofdisturbance. Permafrostdoes not
surface is underlain by 1 to 15 ft (0.3 to 4.6 m) of o~curbeneathmoderateto steepsouth-facingslopes and
sandy silt, which blankets sandy gravel containing hIlltops. Depth to base ofpermafrost in creek valley
lenses ofpebble gravel with scatteredcobbles as large bottoms varies from 8to more than 360ft (2.4 to more
as 3 in. (7.6 em). The alluvial fill is as thick as 700 ft than 110m (fig. 2). Beneathfloodplains ofChenaand
(214 m) and contains numerous buried forest layers. Tanana Rivers, discontinuous masses of perennially
Sinuous sloughfillings ofsandy organic siltup to 30ft frozen groundare interstratifiedwithunfrozen sandand
(9 m) thickwindacross thefloodplain. gravel lenses and layers; permafrost table ranges in
depthfrom 2to 91 ft (0.6to27.8 m), averaging about2
Climate to 5 ft (0.6 to 1.5 m) where shallow; and maximum
known depthofpermafrostranges from 11 to over265
ft (3.4 to over 80.8 ro).
Fairbanks is near the center of the continental
Manylandforms indicativeofpermafrostoccurinthe
climatic zone in interiorAlaska. Winters are normally
vicinity of Fairbanks, including open-system pingos,
long, dark, cold, and dry, and minimum temperatures
low-center .polygons, high-center polygons,
frequently plunge below-40° to -50°F (-40° to -45°C).
thermokarstPIts, beadeddrainage, andthawponds and
lakes.
1 DepartmentofGeology, ArizonaStateUniversity,
Tempe,Arizona85287. Soils
'l Divisio~ofGeologicalandGeophysicalSurveys,
3700AIrportWay,Fairbanks, Alaska99709. On well-drained upland surfaces in the Fairbanks
3 DepartmentofGeology, UniversityofToronto, area, where permafrost is not present, Alfic
Scarborough Campus, Scarborough, Ontario, Cryochrepts (subarctic brown forest soils) exhibit
Canada, MICA4. typical reddish brown to brown profiles 24 to 40 in.
T102: 3
EXPLANATION N
Bedrock hills and loess slopes *
Permafrostfree Thermokarst pit
Dredge tailings • Pingo
Generallyunfrozen
(!)Field trip stop
Flood-plain alluvium
Permafrostwithlowicecontent
Lower hillslope silt and creek valley silt
Permafrostwithhighicecontent
2 3Miles
2 3Kilometers
FIGURE 2 Generalized permafrost map of the Fairbanks area, Alaska, showing location offield trip
stops (modifiedfrom geologicmapoftheFairbanks areabyT.L. Pewe, 1958).
T102: 4