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Geology & Paleantology

Rocks, formations & fossils along the UTB.

The Unaweep/Tabeguache Scenic and Historic Byway runs through the heart of the Uncompahgre Plateau. About 300 million years ago the area that is now the Plateau was uplifted into a mountain range known as the ancestral Rocky Mountains of “lJncompahgria.” Over time the mountain range was eroded down to its roots, furnishing the sand, gravel, and mud for the red rock formations of southwest Colorado. This process of erosion removed over one half billion years’ worth of material from the rock record, causing the Chinle Formation of the Triassic Period to lie directly on the Precambrian rocks. More information is included in the Mile Marker Tour section.


Like the pages of a huge book, the rock layers along the Byway reveal information about environments and species that existed here in the ancient past. Well-preserved fossils of reeds, horsetails, ferns, conifer trees and cycads tell us the area was once a lush forest. Paleontologists have found partial skeletons of the Diplodocus and Camarasaurus, dinosaurs who thrived on the abundant plants. Tracks of small carnivorous dinosaurs have been found from Cactus Park to the Dolores River Canyon. Numerous fossils of shelled invertebrates provide a history of the huge seas and lakes that covered the area. In the cliffs around Placerville, nine new types of early amphibians and reptiles have been discovered. Fossil freshwater fish found in the vicinity of Paradox Valley has provided scientists with new information on the evolution of bony fish. Colorful fossilized trees and dinosaur bones were made into stone tools by prehistoric people. Later, fossils were collected by miners for their heavy concentration of uranium ore. Miners tell of piling fossil bones and trees in ore carts and sending them into the crusher at the Uravan mill. Today, fossils are protected by law and can only be collected with a permit.

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