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Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central AlaskaContinuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.
Document ID
19940015913
Document Type
Conference Paper
Authors
Beget, J. E. (Alaska Univ. Fairbanks, AK, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Workshop on the Martian Northern Plains: Sedimentological, Periglacial, and Paleoclimatic Evolution
Subject Category
LUNAR AND PLANETARY EXPLORATION
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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