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Past permafrost on the Mid‐Atlantic Coastal Plain, eastern United States
Author(s) -
French Hugh,
Demitroff Mark,
Newell Wayne L.
Publication year - 2009
Publication title -
permafrost and periglacial processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.867
H-Index - 76
eISSN - 1099-1530
pISSN - 1045-6740
DOI - 10.1002/ppp.659
Subject(s) - permafrost , geology , coastal plain , geomorphology , shore , frost weathering , sedimentary depositional environment , liquefaction , sedimentary rock , physical geography , geochemistry , oceanography , paleontology , geotechnical engineering , soil water , soil science , structural basin , geography
Sand‐wedge casts, soil wedges and other non‐diastrophic, post‐depositional sedimentary structures suggest that Late‐Pleistocene permafrost and deep seasonal frost on the Mid‐Atlantic Coastal Plain extended at least as far south as southern Delaware, the Eastern Shore and southern Maryland. Heterogeneous cold‐climate slope deposits mantle lower valley‐side slopes in central Maryland. A widespread pre‐existing fragipan is congruent with the inferred palaeo‐permafrost table. The high bulk density of the fragipan was probably enhanced by either thaw consolidation when icy permafrost degraded at the active layer‐permafrost interface or by liquefaction and compaction when deep seasonal frost thawed. Copyright © 2009 John Wiley & Sons, Ltd.