Quaternary and Tertiary sediments seen in exposure along Niobrara Rive

Dark organic-rich beds at top of exposure in fine-grained Quaternary colluvium (?) probably are associated with grade of the fluvial system that was several meters higher than present. Most of the exposure is of underlying Tertiary sediments. Geologic mapping and geochronology of Quaternary terraces will provide constraints on the downcutting history of the Niobrara River to better understand relations such as those shown here.