4. Comprehensive Plan - Laserfiche WebLink

and is considered some of the richest and most productive farmland in the world (Miller and Frink 1982). The plain of Lake Agassiz is flat and nearly featureless with a northward slope of 1.5 feet per mile and a eastward slope ranging from 2 feet per mile near the Red River to 20 feet per mile farther west (USDA 1983,3). At the bottom ofthe Red River Valley lies the Red River of the North, a northward flowing river beginning in southeastern North Dakota and eventually draining into Lake Winnipeg in Canada (United States 2002). Geology The Pleistocene Epoch, which occurred between 10,000 and 1.6 million years ago, was a period of intense cold. Throughout this period glaciers repeatedly passed across North America bringing tremendous ecological and topological changes. During this time ice sheets advanced over the area, as these glaciers retreated a portion in eastern North Dakota was blocked and formed Glacial Lake Agassiz as it melted (Commission ofCass County and the Cass County Planning Department 1988). The eastern two-thirds of the county is the flat plain formed by the sedimentation of the Lake Agassiz. Two types of sediments are present in this area, silt and clay, which sit atop the till and associated glacial and stream deposits. Beach ridges and deltas are the principle relief features of this area; a locale containing some of the most fertile soils in the nation (Commission ofCass County and the Cass County Planning Department 1988). The western one-third ofthe county to the east of the lake plain is an area descriptively referred to as the "Drift Prairie." This plains area is modified by slightly eroded glacial drift forming low and relatively rough hills and gentle rolling topography. These features, the result of the retreating ice sheets are also the location ofthe majority of the county's wetlands (Commission ofCass County and the Cass County Planning Department, 1988) (Figure 1.2). 4