The Excavation (09/20/2002) This view down toward the main quarry gives a good idea of the make up of the land. Correct me if I am wrong. The top layer contains bentonite. There is then a hard limestone layer. The red sandstone held the fossils.
Dinosaur Hill is a few miles outside the west entrance to Colorado National Monument. The hill is an exposed section of the easily eroded Morrison Formation which was deposited about 150 Million years ago in the Late Jurassic period (when dinosaurs ruled the earth).
The early settlers in the valley had found dinosaurs perhaps as early as 1880. The natives probably knew about the bones several centuries before that.
On hearing of the discoveries from Dr. S.M. Bradbury of the Western Colorado Academy of Sciences in 1899, Elmer S. Riggs of the Field Museum in Chicago planned a westward expedition. In 1900 he explored Riggs Hill, where he found fossilized remains of a Brachiosaurus altithorax.
In 1901, Riggs returned to the area and made the discovery of Dinosaur Hill where he removed the bottom 2/3rds of an Apatosaurus (Brauntosaurus) excelsus. The findings from this expedition were shipped to the Chicago Field Museum, where it is still on display.
Today Dinosaur Hill is a nice walk, on a well maintained trail just south of Fruita. It is a good place to stretch your legs on the long journey across Interstate 70