Stratigraphy and paleoecology of the Morrison Formation, Como Bluff, Wyoming

The Morrison Formation at Como Bluff, Wyoming, has been historically known for containing vertebrate fossils. However, many of these fossils were not put into a stratigraphic or sedimentologic framework. At the base of the Morrison Formation is a marine sandstone known as the Windy Hill Member. The middle member is the Lake Como Member, which contains illitic clay, caliche rich paleosols, and typical dinosaurian fossils. The Talking Rocks Member is the upper most member and contains smectite-rich mudstones and aquatic vertebrate fossils, including some species thought to be restricted to the Cretaceous Period. The contact between the Morrison Formation and the overlying Cloverly Formation is placed at the base of the Cloverly conglomerates. In some areas, a zone of kaolinitic and carbonaceous shale containing Cretaceous-like plant material can be found just below the Morrison/Cloverly contact suggesting that the Morrison Formation may be in part Cretaceous in age.