Cold-based Laurentide ice covered New England's highest summits during the last glacial maximum

To better understand glacial history and process in New England (northeastern United States), a mountainous area overrun by the Laurentide Ice Sheet, we measured three cosmogenic nuclides in nine upland samples. The concentrations of 10Be and 26Al in some samples collected near the summits of Katahd...

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Bibliographic Details
Published in:Geology (Boulder) 2015-12, Vol.43 (12), p.1059-1062
Main Authors: Bierman, Paul R, Davis, P. Thompson, Corbett, Lee B, Lifton, Nathaniel A, Finkel, Robert C
Format: Article
Language:English
Subjects:
Al-26
alkaline earth metals
aluminum
Be-10
beryllium
C-14
carbon
Cenozoic
cosmogenic elements
deglaciation
erosion rates
exposure age
Geochronology
Geology
Glaciers
isotopes
last glacial maximum
Laurentide ice sheet
Little Haystack Mountain
Maine
metals
Mount Katahdin
Mount Washington
New England
New Hampshire
Piscataquis County Maine
Pleistocene
Quaternary
Quaternary geology
radioactive isotopes
Soil erosion
Topography
United States
upper Pleistocene
Valleys
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Summary:To better understand glacial history and process in New England (northeastern United States), a mountainous area overrun by the Laurentide Ice Sheet, we measured three cosmogenic nuclides in nine upland samples. The concentrations of 10Be and 26Al in some samples collected near the summits of Katahdin (Maine) and Mount Washington and Little Haystack Mountain (New Hampshire) are 2-10 times higher than expected for a single exposure period, considering field evidence indicating that continental ice-covered all New England peaks during the Last Glacial Maximum. In-situ 14C exposure ages from the summits are much younger, suggesting that high-elevation sampling sites were ice-covered before and during the Last Glacial Maximum. Field and isotopic data are consistent with New England summits being covered in part by cold-based continental ice that did not erode much rock. The contrast in erosion rates between stable summits and deeply eroded valleys likely contributes to the development and maintenance of northern Appalachian topography.
ISSN:0091-7613
1943-2682
DOI:10.1130/G37225.1