Sea-level records from the U.S. mid-Atlantic constrain Laurentide Ice Sheet extent during Marine Isotope Stage 3

• Published in: Nature communications Vol. 8; no. 1; p. 15612
• Main Authors: Pico, T, Creveling, J. R., Mitrovica, J. X.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30-05-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/413; 704/2151/210; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15612

The U.S. mid-Atlantic sea-level record is sensitive to the history of the Laurentide Ice Sheet as the coastline lies along the ice sheet’s peripheral bulge. However, paleo sea-level markers on the present-day shoreline of Virginia and North Carolina dated to Marine Isotope Stage (MIS) 3, from 50 to 35 ka, are surprisingly high for this glacial interval, and remain unexplained by previous models of ice age adjustment or other local (for example, tectonic) effects. Here, we reconcile this sea-level record using a revised model of glacial isostatic adjustment characterized by a peak global mean sea level during MIS 3 of approximately −40 m, and far less ice volume within the eastern sector of the Laurentide Ice Sheet than traditional reconstructions for this interval. We conclude that the Laurentide Ice Sheet experienced a phase of very rapid growth in the 15 kyr leading into the Last Glacial Maximum, thus highlighting the potential of mid-field sea-level records to constrain areal extent of ice cover during glacial intervals with sparse geological observables.
Surprisingly high Pleistocene sea-level markers on the Virginia and North Carolina shoreline are inconsistent with models of Laurentide ice sheet volume during Marine Isotope Stage 3. Here, Pico
et al
. present a revised glacial isostatic adjustment model that enables them to reconcile these differences.