The Precambrian in Colorado, US

Paleontology and geology

Precambrian rocks form the core of the Rocky Mountains and include metamorphic rocks as old as 2.7 billion years and intrusive igneous rocks around a billion years old. The only Precambrian sedimentary rocks in Colorado are located in the extreme northwest corner of the state on the eastern margin of the Uinta Mountains. No fossils have been reported from these rocks.