Geoscience Reference
In-Depth Information
The grinding advance and retreat of glaciers left their dramatic marks on the coastline of Maine.
The Northern Hemisphere currently receives less solar energy than its southern counterpart, periodically
causing the ice sheets to grow. The largest was the Laurentide ice sheet, which originated in the Laurentian re-
gion of Canada and once covered all of North America east of the Rockies, reaching as far south as St. Louis,
Missouri. There were four major advances of the Lau-rentide ice sheet. The last was the Wisconsinan ice sheet,
which gouged out the Laurentian Channel in the Gulf of St. Lawrence, eventually filled the gulf and the Bay of
Fundy and advanced across Nova Scotian to the edge of the Scotian Shelf. Twenty-five thousand years ago, it
