The
Glacial Lake Souris occupied the basin of the
Souris River from the most southern portion of this river's loop in
North Dakota to its elbow in
Manitoba, where it turned sharply northward and passed through the Tiger Hills. The length of Lake Souris was about 170 miles, from
latitude 48° to latitude 50°35', and its maximum width, north of
Turtle Mountain, was nearly 70 miles. It was situated near the far southeast corner of the large glacial
Lake Agassiz, separated from it by another small glacial body, Glacial Lake Hind.