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Interglacial Extension of the Boreal Forest Limit in the Noatak Valley, Northwest Alaska: Evidence from an Exhumed River-Cut Bluff and Debris Apron

Arctic, Antarctic, and Alpine Research

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Abstract

Numerous exposures of Pleistocene sediments occur in the Noatak basin, which extends for 130 km along the Noatak River in northwestern Alaska. Nk-37, an extensive bluff exposure near the west end of the basin, contains a record of at least three glacial advances separated by interglacial and interstadial deposits. An ancient river-cut bluff and associated debris apron is exposed in profile through the central part of Nk-37. The debris apron contains a rich biotic record and represents part of an interglaciation that is probably assignable to marine-isotope stage 5. Pollen spectra from the lower part of the debris apron closely resemble modern samples taken from the Noatak floodplain in spruce gallery forest, and macrofossils of spruce are also present at this level. Fossil bark beetles and carpenter ants occur higher in the debris apron. Mutual Climatic Range (MCR) estimates from the fossil beetles suggest temperatures similar to or warmer than today. Together, these fossils indicate the presence of an interglacial spruce forest in the western part of the Noatak Basin, which lies about 80 km upstream of the modern limit of spruce forest.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Interglacial Extension of the Boreal Forest Limit in the Noatak Valley, Northwest Alaska: Evidence from an Exhumed River-Cut Bluff and Debris Apron
Series title:
Arctic, Antarctic, and Alpine Research
Volume
35
Issue:
4
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
460
Last page:
468
Number of Pages:
9