Holocene geomorphic and stratigraphic framework of archeological sites along the missouri river, central south dakota

Abstract

Abstract : This report summarizes the depositional and erosional history of the late Wisconsin and Holocene strata of the Missouri River Trench in South Dakota. It also proposes a model of Sedimentation and erosion based on a modification of the work of Clayton et al. (1976). Finally, it relates the new model to the interpretation of archeological sites in the Big Bend Reservoir, South Dakota. Previous geological thought on the origin of the terrace levels of the Missouri River and the sediments on them is reviewed from the period of the 1950's to the 1980's to show the significance and evolution of these ideas. The concepts adopted here are based on the work of Clayton et al. (1970) in North Dakota as applied, tested and modified in the Lake Sharpe, South Dakota area using detailed analysis of various geologic and archeological sites. In the revised model emphasis is put on the erosional surfaces which separate depositional units of the Holocene strata rather than on the sedimentary units themselves. These erosional surfaces and their related paleosols provide a practical means of separating and identifying time-stratigraphic depositional intervals in the Holocene section which in archeological terms contain cultural levels which range from Paleoindian to Plains Village.