North-Central Section - 50th Annual Meeting - 2016

Paper No. 27-5
Presentation Time: 8:00 AM-12:00 PM


HEATH, Stephanie L. and LOWELL, Thomas V., Department of Geology, University of Cincinnati, 500 Geology/Physics Building, Cincinnati, OH 45221,

To explore the link between ice sheet behavior and climate, we asked what happened to the margin of an ice sheet during established cold intervals. We chose the Heinrich Stadials, as recorded as cooler surface water temperatures across the North Atlantic in marine records. Of specific interest were Heinrich Stadials 2 and 1, which occurred from 27.1 to 23.3; and 17.7 to 14.6 ka, respectively. In the simplest view, the ice sheet margin should be advancing during these times.

We compiled all available chronologic data defining the advance and retreat patterns of the Laurentide Ice Sheet from samples collected within 50 kilometers of the southernmost extent. This analysis only considered ages that fall between 12.0 and 30.0 ka. We summarize the behavior of various sectors of the ice sheet during HS2 and HS1 in the table below.

Ice Sheet Sector HS2 Interstadial HS1
New England Reached maximum >HS2; Retreat  Retreat Retreat
Lake Huron/Erie Lobe Advance Reached maximum extent Retreat
Lake Michigan Lobe Advance Reached maximum early interstadial; Retreat  Retreat
Green Bay/Chippewa Lobes  Reached maximum >HS2; Retreat Retreat Retreat
Des Moines Lobe Unknown Unknown Advance
James Lobe Unknown Unknown Unknown

Based on our analysis, it appears that the lobes of the southern margin of the LIS did not advance and retreat synchronously. More important, the southern LIS margin did not respond to cooling in the North Atlantic during Heinrich Stadials 2 and 1. We put forth the suggestion that local climate conditions, or more specifically ablation rates, may have played a large role in the behavior of the individual lobes.