Contact Info
Missouri River Institute
The University of
South Dakota
414 E. Clark Street
Science Center
Vermillion, SD 57069

Financial support for website development provided by the
Living River Group
of the
Sierra Club




Site Description:

Steep bluffs on the south side of the Missouri River east of Bow Creek expose the area's diverse geologic history. During the Cretaceous Period, between 144 and 65 million years ago, an inland sea covered a large portion of the continent's interior. This interior sea advanced and retreated several times from the west, depositing sandstones, shales and limestones, leaving behind the formations exposed at this location; Niobrara chalk and Carlile shale. The contrasting landscapes in this reach of the river, steep bluffs to the south and nearly flat topography extending far to the north, are a result of several glacial advances that began 1.5 million years ago. The Missouri River's current route marks the southern extent of the most recent glacial advance.