Souris and Des Lacs River Valleys


There must have been a horrendous amount of water on the landscape at the end of the last ice age. With all that ice melting, water must have been all over the place. I thought about that recently when I looked across the Souris River Valley from Minot’s north hill.

The river valley there is quite impressive. It is deep and wide, but the present Souris River is not. It makes one wonder how it all formed. At one time was there enough water flowing through this area to form the valley, or was the valley formed some other way, and is now just providing a topographic low for the river to flow through?

The Souris River is an underfit river. It flows through a large valley, actually a spillway, formed by massive amounts of glacial meltwater at the end of the last ice age.

Toward the end of the last ice age, as the glaciers were melting, lakes were occasionally formed at the front of the glacier. One of those lakes in our region was Glacial Lake Regina. The southern terminus of glacial Lake Regina would have been near Weyburn, Saskatchewan. From there the lake stretched northwestward, covering perhaps thousands of square miles.

At some point, the water of Glacial Lake Regina broke out of the lake’s southern end, releasing a torrent of water in an extremely short time span. This cataclysmic release of water flowed southeastward cutting out what is today the Souris River and Des Lacs river valleys. Geologically, these river valleys, roughly the segments upstream from the Velva area, are occasionally referred to as the Souris and Des Lacs Spillways.

Glacial Lake Souris at that time occupied much of the present Souris River Valley and adjacent land further downstream. As a result, the morphology of the Souris River valley in these two stretches is noticeably different. Compare, for example, the Souris River valley where it crosses highway 5 west of Moholl with the river west of Bottineau.

So the next time you look across the Souris River valley in Minot, give some consideration to the torrent of water that carved out the valley from a cataclysmic draining of a lake near Regina, Saskatchewan.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.

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