Lake Agassiz << AG uh `see` >> was the largest glacial lake in North America. It covered much of the area of present-day Manitoba and northwestern Ontario, and portions of Saskatchewan, North Dakota, and Minnesota. The lake was created late in the Pleistocene Epoch, a time marked by a succession of ice ages that ended about 11,500 years ago (see Ice age ). As the Laurentide Ice Sheet, which covered the area, moved northeastward, it left a large, shallow basin behind it. Melting ice and river water filled the basin to form Lake Agassiz. The lake reached its maximum area of about 135,100 square miles (350,000 square kilometers) between 7900 B.C. and 7500 B.C. When the ice continued to melt at the lake’s north and east shores, the waters drained away toward Hudson Bay. Several smaller lakes, including Winnipeg, Winnipegosis, and Manitoba, were left in the deeper part of the area. The plain of Canada’s Red River, one of the world’s most fertile wheat-growing regions, is the former lake bed. See also Red River of the North .
