Even at night, under a dark sky and brilliant stars, you can see some of the geology, "twenty-three rock layers [of which] are exposed at the monument. These rock layers are remnants of extinct ecosystems spanning nearly a billion years, from ancient seas, to plains where dinosaurs roamed, to Sahara-like deserts that were home to tiny, early mammals. The rock layers at Dinosaur make up one of the most complete stratigraphic columns exposed within the National Park System. With the exception of the Ordovician, Silurian, and Devonian, all of the geologic periods are represented in the Dinosaur area. Almost all of the rocks exposed in the area are sedimentary and range in age from Precambrian (about 1,100 million years ago) to Miocene (about 25 to 10 million year ago)."