Paleontology and geology
Little sediment accumulated in Colorado during the early Jurassic, but the deposition of Morrison Formation sediments in the Late Jurassic finally covered the last remnants of the Ancestral Rockies. The Morrison Formation formed as a series of streams, lakes, and rivers traced across the region, depositing a thick sequence of sandstone and mudstone. Fossil dinosaur bones were first discovered near the town of Morrison, just west of Denver, in 1877. This discovery soon led to others, and it became apparent that the Late Jurassic was a time of large dinosaurs. Major quarries in western Colorado have yielded many kinds of large sauropods, as well as smaller dinosaurs such as stegosaurs, allosaurs, ceratosaurs, and camptosaurs. Subsequent discoveries of fossil plants, mammals, lizards, and plants make the Morrsion one of the most famous formations in the world.