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This anaglyph was produced by Ray Sterner of the Applied Physics Laboratory at Johns Hopkins University using USGS DEM data.

The distances across the image are approximately 100 miles by 100 miles. Although the actual vertical relief across the image is only about 800 feet, the vertical exaggeration perceived in the image is much higher (150X).

Most of the region shown was intensively glaciated during the Pleistocene ice ages. Glaciers only marginally extended southwest of the Missouri River. Thus the landscape to the southwest of the Missouri on this image contrasts sharply with the "softer," glaciated topography elsewhere.

Trending across the lower third of the image is part of the Missouri Coteau, a surface of dead-ice moraine bordered to the northeast by the prominent northeast-facing Missouri Escarpment. As glacial ice passed up and onto the Coteau, intensive shearing of the ice masses often occurred, leaving such ice-thrust complexes as the Prophets Mountains.

Like the Missouri Coteau, the Turtle Mountains are a hummocky upland of dead ice moraine, formed where ice was forced up a steep, bedrock escarpment. The Turtle Mountains are today covered by woodlands - the most extensive zone of forested lands in North Dakota.

To the southwest of the Turtle Mountains is the plain of Glacial Lake Souris: a large lake that formed at the end of the last ice age. Unlike Lake Agassiz, Lake Souris was not ice-dammed. It, however, occasionally received massive floods from releases of ice-dammed lakes to the north -- particuarly from Glacial Lake Regina (in Saskatchewan) via the Des Lacs and Souris River spillways. These catastrophic flood releases widened and deepened the valleys of both rivers, with flood drainages rejoining into a single channel (Souris River) near Minot. As these flood outbursts entered into Lake Souris, a sediment fan was built up at the mouth of the river, represented today in part by the dune field near Denbigh, ND.

A north-south continental divide sub-parallels the Missouri Escarpment in this image. Northeast of this divide, waters drain northward via the Sheyenne-Red River system, ultimately being delivered into Hudson Bay via the Nelson River. Waters southwest of this divide drain southward via the James-Missouri River system, ultimately to arrive at the Gulf of Mexico via the Mississippi River.

The prominent lines impressed at 48° N. lat. and at 100° and 101° W. long. represent artifacts from suturing DEM datasets together to produce this image. They do not reflect any real structure. In addition, some of the flat step-like areas are due to the contours on the original maps that were digitized by USGS to obtain the elevation data and therefore do not represent real topography.

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