Eventually , the Cretaceous Seaway covered the Dakota , depositing the Mancos Shale .
Early in the Cretaceous , similar nonmarine sediments were laid down and became the Dakota Sandstone .
The Cretaceous Seaway covered the Dakota Sandstone , depositing the Mancos Shale .
Early in the Cretaceous , similar nonmarine sediments were laid down and became the Dakota Sandstone .