Glaciated Plains


I recently drove highway 2 between Rugby and Grand Forks.  For most of the trip the landscape consisted of gently rolling farmland on what geologists call the Glaciated Plains.  It is one of the most important crop producing regions of the state.

The Glaciated Plains (sometimes called the Drift Prairie) lies between the Red River Valley (glacial Lake Agassiz) to the east and the Missouri Coteau to the west.  The Coteau is a roughly thirty mile wide band of more hilly country with greater relief that lies roughly parallel to and on the north and east and north side of the Missouri River.

The Glaciated Plains is, as the name implies a glaciated landscape shaped by active ice during the end of the last ice age.  The active glaciers formed a landscape that may be characterized as having a gently rolling topography with relief generally less than a hundred feet although it can be much higher in places.

The boundary between the Glaciated Plains and the Red River Valley lies roughly along a line from the western border of Pembina County southward to the Sargent and Richland County line.   If you travel eastward on highway 2 you start to drop down off the Glaciated Plains near Niagara and by time you approach the Grand Forks Air Force Base you are in the Red River Valley.  On Interstate 94 the break is less obvious but occurs in the area around the Buffalo-Alice exit.

The Glaciated Plains extends westward to the Missouri Escarpment, which rises upward several hundred feet to the Missouri Coteau.  This boundary runs roughly northward from western Dickey County to north central Stutsman County.  From there it trends northwestward to the northwest corner of the state in central Divide County.

The landform that characterizes the Glaciated Plains is what many of you probably learned as ground moraine, but more recently is referred to as undulating collapsed topography.  It consists of glacial till (glacial drift) which is a mixture of ground up rock material ranging in size from clay and silt, to sand, gravel, rocks and boulders deposited at the base of moving glaciers or as the glaciers melted.  The depth of the glacial till is quite variable, but is generally a hundred feet thick or more.

“No Ordinary Plain:  North Dakota’s Physiography and Landforms” by John Bluemle and Bob Biek.

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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