Why does the Red River flow north?
Lake Agassiz, a lake formed by melting glaciers, covered much of what is today western Minnesota, eastern North Dakota, southern Manitoba, and southwestern Ontario
from about 12,500 years ago to about 7,500 years ago. Lake Agassiz virtually
disappeared, leaving a few remnants like Minnesota's Upper and Lower Red Lakes
and Lake of the Woods and Canada's Lake Winnipeg, Lake Manitoba, and Lake
Winnipegosis. Lake Agassiz also left a fertile, flat plain that
drains to the north, ultimately to Hudson Bay. The Red River flows north through this plain to Lake
Winnipeg because, despite the plain being very flat, a difference in elevation
exists along the route of the river, making the line between southeastern North Dakota and Lake Winnipeg slightly downhill. At the confluence of the Bois de Sioux and Otter Tail
Rivers near Wahpeton, North Dakota, where the Red River begins, the elevation is 943 feet above mean sea level. The elevation of Lake Winnipeg is 714 feet above mean sea level.
This web site has a page at http://nd.water.usgs.gov/pubs/key/redriver.html
with links to U.S. Geological Survey information about the Red River and its
basin, including publications, hydrographs, and pictures.
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U.S. Department of the Interior |
U.S. Geological Survey
