NORTH DAKOTA STATE UNIVERSITY - FARGO, N D SLUMP AT FARGO, N.D. Click on the photo for an enlarged image. (90K) This slump at the 12th Avenue North overpass at Interstate 29 occurred in clay-rich materials used in the overpass construction. In the Red River Valley, slumps such as this are a common problem on both overpasses and in highway roadcuts. As is common, this slump terminates in an earthflow-like form. (Photo by D.P. Schwert, North Dakota State University, 2000). [ Mass Wasting Features of North Dakota ]