Garrison, E.G., . Sea-level evidence for a significant reduction of the Laurentide Ice Sheet in MIS 3, Georgia Bight, southeastern United States.
Recently, a hypothesis was proposed for a significant reduction of the central region of the Laurentide Ice Sheet (LIS) from ca. 52 to 40 kYBP during marine isotope stage (MIS) 3. Corroborative evidence for this hypothesized reduction exists in the form of ages for higher sea levels in the Georgia Bight of the U.S. continental shelf, which have been dated to early MIS 3 using a variety of methods. These sea-level ages (15) were documented during ongoing continental shelf research conducted over the past two decades in the Georgia Bight and support the idea of a much-reduced LIS in early MIS 3 in synchrony with previously published geological and age data from the Hudson Bay Lowland of central Canada. The agreement between these data sets supports the need for a careful reassessment of late Pleistocene climate variability, ice retreat/advance, and a coupled sea-level response to both. This report reviews present and past research on paleoclimate in MIS 3 in order to place the age data in a broader perspective of sea-level and ice-volume drivers. Glacio-isostatic adjustment is also addressed as an important factor in near- and intermediate-field mantle response along the Atlantic coast of the United States to LIS ice loading during MIS 3.