Past permafrost on the Mid‐Atlantic Coastal Plain, eastern United States

• Published in: Permafrost and Periglacial Processes
• Main Authors: Hugh French, Mark Demitroff, Wayne L. Newell
• Format: Article in Journal/Newspaper
• Language: unknown
• Subjects: permafrost; wedge*
• Online Access: https://doi.org/10.1002/ppp.659

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.