Geology of Ft. Ransom

August 20, 2009

Ft. Ransom and the surrounding area is a huge glacial meltwater trench as the photo above shows. About 25,000 years ago, this part of North Dakota was covered by the vast Wisconsin Glacier which included almost all of Canada, Minnesota, Wisconsin as well as eastern North Dakota. According to Elwyn B. Robinson, in History of North Dakota, the retreating glacier left sand dunes in Ransom County as well as cutting trenches or valleys to enable the water to run off.

The Sheyenne River valley was one of those trenches and continues to flow to the south east in this region. After it reaches Lisbon ND, the river turns to the east and then to the northeast where it runs into the Red River of the North near Fargo.

The Sheyenne River drained water from the glacial Lake Souris in Central North Dakota and carried it to the glacial Lake Agassiz which was located a short distance east of here. At that time the water filled the valley, shown above, covering a mile wide and over 300 feet deep. The valley you see in the photo is all Ft. Ransom State Park.

Other evidence of glacial activity in the area is the array of large rocks and boulders when are stewn all over the landscape.