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Visual-Stratigraphic Dating of the GISP2 Ice Core: Basis, Reproducibility, and ApplicationAnnual layers are visible in the Greenland Ice Sheet Project 2 ice core from central Greenland, allowing rapid dating of the core. Changes in bubble and grain structure caused by near-surface, primarily summertime formation of hoar complexes provide the main visible annual marker in the Holocene, and changes in "cloudiness" of the ice correlated with dustiness mark Wisconsinan annual cycles; both markers are evident and have been intercalibrated in early Holocene ice. Layer counts are reproducible between different workers and for one worker at different times, with 1% error over century-length times in the Holocene. Reproducibility is typically 5% in Wisconsinan ice-age ice and decreases with increasing age and depth. Cumulative ages from visible stratigraphy are not significantly different from independent ages of prominent events for ice older than the historical record and younger than approximately 50,000 years. Visible observations are not greatly degraded by "brittle ice" or many other core-quality problems, allowing construction of long, consistently sampled time series. High accuracy requires careful study of the core by dedicated observers.
Document ID
20000038174
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Alley, R. B.
(Pennsylvania State Univ. University Park, PA United States)
Shuman, C. A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Meese, D. A.
(Army Cold Regions Research and Engineering Lab. Hanover, NH United States)
Gow, A. J.
(Army Cold Regions Research and Engineering Lab. Hanover, NH United States)
Taylor, K. C.
(Desert Research Inst. Reno, NV United States)
Cuffey, K. M.
(Washington Univ. Seattle, WA United States)
Fitzpatrick, J. J.
(Geological Survey Denver, CO United States)
Grootes, P. M.
(Kiel Univ. Germany)
Zielinski, G. A.
(New Hampshire Univ. Durham, NH United States)
Ram, M.
(State Univ. of New York Buffalo, NY United States)
Spinelli, G.
(Pennsylvania State Univ. University Park, PA United States)
Elder, B.
(Army Cold Regions Research and Engineering Lab. Hanover, NH United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1997
Publication Information
Publication: Laboratory for Hydrospheric Processes Research Publications
Subject Category
Oceanography
Distribution Limits
Public
Copyright
Other

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