The purpose of this reconnaissance is to assess the potential of the Pierre Shale, of Late Cretaceous age, as a possible isolation medium for radioactive wastes. The regional stratigraphic and structural setting of the Pierre Shale in the northern Great Plains is summarized from subsurface data.
Geologic attributes mapped and employed in the identification of areas warranting further evaluation are: depth to the base of the Pierre Shale, shale thickness, overburden thickness, lithology and mineralogy of the shale, and penetrations by oil and gas wells. Three areas emerge as most favorable; each may contain many potential disposal sites. These large geologic study areas are further described on the basis of general structural and seismic considerations and are compared with respect to topography and mineral and water resources.
A large area in west-central South Dakota is recommended for extensive further study. A smaller area in northeastern Colorado also may warrant additional investigation. A relatively small area in north-central North Dakota is also delineated, but currently is not proposed for further studies.
