Glacial Lake McKenzie

Glacial Lake McKenzie was a prehistoric lake in present-day North Dakota that formed during the Pleistocene when ice from the Keewatin Lobe blocked older river drainage routes. Before glaciation, rivers in North Dakota, South Dakota, and eastern Montana flowed northeast toward Canada and Hudson Bay, but advancing ice forced water to collect and find new paths. Rivers first moved eastward along the glacier front through a valley between Garrison and Riverdale, but that route was also sealed by ice, creating the lake. When its waters overtopped the south ridge near Riverdale, they cut a diversion trench that established the route the modern Missouri River now follows.

North Dakota · United States