By: Douglas A. Sprinkel, Scott K. Madsen, James I. Kirkland, Gerald L. Waanders, and Gary J. Hunt
Cedar Mountain and Dakota Formations Around Dinosaur National Monument. Evidence Of The First Incursion Of The Cretaceous Western Interior Seaway Into Utah.
This 20-page report describes the stratigraphy of the Cedar Mountain and Dakota Formations in and around Dinosaur National Monument in northeast Utah and includes new palynology and radiometric age data. The contact between these formations is unconformable in which the Dakota Formation has incised into the underlying Cedar Mountain Formation. Locally, the Dakota includes a basal marine mudstone and shale until that contains late Albian dinoflagellate cysts, which represents peak sea level during the Kiowa-Skull Creek depositional cycle and indicates the first marine incursion of the Cretaceous Western Interior Seaway into Utah.