The geology of eastern Wells County, North Dakota

Late Wisconsinan (Pleistocene) glaciation was responsible for the varied landforms of eastern Wells County. The Burnstad-Streeter phase advanced from the north-northeast about 10,000 to 12,000 years ago and was obstructed by the elevated Missouri Coteau which caused basal shearing and subsequent movement of subglacial drift into the ice. As this ice stagnated, the resultant drift cover impeded ablation and insulated the waters of superglacial lakes present on the surface of the Coteau at that time. Abundant Pleistocene fossils have been found in the sediments of these former lakes. Upon complete ablation, characteristic dead-ice features resulted on the surface of the Missouri Coteau. The Turtle Mountain bedrock high in southern Manitoba and north-central North Dakota caused the thinning ice to separate into two lobes, the Souris lobe and the Leeds lobe. The Souris lobe advanced from the northwest into eastern Wells County and formed the Grace City ground moraine with its directional features and superimposed meltwater channels. A major stillstand of this phase formed the Martin end moraine to the northwest of the area. The essentially contemporaneous Leeds lobs advanced from the north-northeast. The Heimdal end moraine was formed during a major stillstand of this lobe. The Heimdal diversion channel provided an initial outlet for glacial Lake Souris in north-central North Dakota after spillways draining glacial Lake Souris had breached the Martin end moraine to the northwest. This channel was subsequently abandoned and formed the Sheyenne River diversion channel to the north. These diversion channels and Rocky Run and Pipestem-Little Pipestem Creek meltwater channel contain abundant sand and gravel and are excellent potential aquifers