LATE JURASSIC MORRISON FORMATION
The updated 042612
Tithonian: Brushy Basin Member: Much finer-grained than the Salt Wash Member, the Brushy Basin Member is dominated by mudstone rich in volcanic ash. Rivers flowed from the west into a basin that contained a giant, saline alkaline lake called Lake T'oo'dichi' and extensive wetlands that were located just west of the modern Uncompahgre Plateau. Deposition in the Morrison Formation ended about 147 Ma. The latest Morrison strata are followed by a thirty-million year gap in the geologic record. In Laurasia you see a new ornithopod fauna with new theropod families. There is a gradual change in flora as flowering plants spread. You still find ecologies in Gondwana into the Late Cretaceous.