Coteau du Missouri

Coteau du Missouri

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Coteau du Missouri

Map of Palliser's Triangle. Canadian section of the Coteau du Missouri

The Coteau du Missouri, or Missouri Plateau, is a large plateau that stretches along the eastern side of the valley of the Missouri River in central North Dakota and north-central South Dakota in the United States. This physiographic region of Saskatchewan and Alberta is classified as the uplands Missouri Coteau which is a part of the Great Plains Province or Alberta Plateau Region which extends across the south east corner of the province of Saskatchewan as well as the south west corner of the province of Alberta. ^[1]Historically, in Canada the area was known as the Palliser's Triangle regarded as an extension of the Great American Desert and unsuitable for agriculture and thus designated by Canadian geographer and explorer John Palliser. The terrain of the Missouri Coteau features low hummocky, undulating, rolling hills, potholes, and grasslands.^[2]

Geologically the plateau is part of the extended plateau of the Great Plains in the Dakotas, and is separated from the main plateau to the west by the Missouri River Trench. The plateau is underlain by Pierre shale covered with hardened deposits from repeated glaciations. The plateau also contains deposits of lignite, mirabilite (sodium sulfate), and bentonite. While subjected to continental glaciation, it was north and west of the Driftless Area, an area which escaped glaciation.

The plateau is poorly drained and is interspersed with glacial kettle lakes. It is transversed by several broad sags marking the ancient stream valleys of the eastern continuations of the Grand, Moreau, Cheyenne, Sheyenne River, Bad, and White rivers.

To the east of the plateau, the lowland valley of the James River was formed by the lobe of the most recent ice age, separating the plateau from the Coteau des Prairies to the east.

Agriculturally the plateau is a grain and livestock region.