Colorado Group

rdf:langString Colorado Group

rdf:langString Colorado Group

rdf:langString yes

rdf:langString Colorado and Kansas:

rdf:langString Elsewhere:

rdf:langString middle Albian to Santonian

rdf:langString ,

rdf:langString Cretaceous

rdf:langString , , , ,

rdf:langString more than

rdf:langString Colorado is a geologic name applied to certain rocks of Cretaceous age in the North America, particularly in the western Great Plains. This name was originally applied to classify a group of specific marine formations of shale and chalk known for their importance in Eastern Colorado. The surface outcrop of this group produces distinctive landforms bordering the Great Plains and it is a significant feature of the subsurface of the Denver Basin and the Western Canadian Sedimentary Basin. These formations record important sequences of the Western Interior Seaway, and as the geology of this seaway was studied, this name came to be used in states beyond Colorado, but was later replaced in several of these states with more localized names. The USGS convention has been to use Colorado Group where the rocks are further divided into formations, Colorado Formation where no beds are developed enough to be mapped as formations, and Colorado Shale where the unit is composed of little more than shale with no distinctive structures (such as in north-central Montana).

rdf:langString yes

rdf:langString Colorado, specifically for the hogbacks and plains facing the Front Range of that state

rdf:langString Siltstone, Conglomerate, Limestone, concretionary beds