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Geology of the Yukon-Tanana area of east-central Alaska

By
Helen L. Foster
Helen L. Foster
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025
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Terry E. C. Keith
Terry E. C. Keith
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025
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W. David Menzie
W. David Menzie
U.S. Geological Survey, Reston, Virginia 22092
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Published:
January 01, 1994

Abstract

East-central Alaska as described in this volume (Fig. 1) is a physiographically diverse region that includes all or parts of the following physiographic divisions (Wahrhaftig, this volume): Northern Foothills (of the Alaska Range), Alaska Range (north of the northernmost strand of the Denali fault system), Tanana- Kuskokwim Lowland, Northway-Tanacross Lowland, and the Yukon-Tanana Upland. The Northern Foothills are largely rolling hills in Pleistocene glacial deposits and dissected Tertiary nonmarine sedimentary rocks. The included part of the Alaska Range is composed of highly dissected terranes of metamorphic rocks that have been intruded by Cretaceous and Tertiary igneous rocks. Mountain peaks reach altitudes as high as 4,000 m, and relief is commonly more than 1,000 m. Glaciers have carved a rugged topography. The Tanana-Kuskokwim Lowland is covered with thick glacial, alluvial, and wind-blown deposits. The Northway-Tanacross Lowland consists of three small basins mantled with outwash gravel, silt, sand, and morainal deposits. The Yukon-Tanana Upland, the largest of the physiographic divisions, consists of maturely dissected hills and mountains with altitudes as high as 1,994 m, and relief ranging from a few to hundreds of meters. Some of the highest areas supported small alpine glaciers during the Pleistocene, and rugged topography resulted locally.

With the exception of the Alaska Range, outcrops in eastcentral Alaska are commonly widely scattered and small, due to extensive surficial deposits and vegetation. The vegetation ranges from heavy spruce forests along large streams to tundra at elevations of approximately 1,000 m. The region is largely in the zone of discontinuous

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Contents

DNAG, Geology of North America

The Geology of Alaska

George Plafker
George Plafker
U.S. Geological Survey MS 904, 345 Middlefield Road Menlo Park, California 94025
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Henry C. Berg
Henry C. Berg
115 Malvern Avenue Fullerton, California 92632
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Geological Society of America
Volume
G-1
ISBN electronic:
9780813754536
Publication date:
January 01, 1994

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