WSP07960 - Laserfiche WebLink

Home Browse Search

. . 13 - ,-. ~. The Jurassic Morrison Formation is well-known for its prolific production of dinosaur bones from many localities around the western interior part of the lr' - United States. Probably the best known such locality is the quarry at Dino- c:. saur National Monument, just a few miles west of the Juniper - Cross 'lountain Project area. Within the project area itself there are only two very small, poorly exposed outcrops of the Morrison Formation. These occur along the north and south banks of the Yampa River at Juniper Hot Springs, where the river has eroded down through the Brown's Park Formation which blankets the folded Morrison and other Mesozoic and Paleozoic formations over a fairly large area in that general vicinity. No fossils were noted at either of these two outcrops; and no dinosaur bones were reported by local residents as having been found anywhere within the project area. The very thick sequence of Cretaceous formations exposed in rather specta- cular fashion in the region of the upper reaches of the proposed Juniper Reservoir consists of alternating marine, nonmarine, and transitional de- posits, which record fluctuations of sea level over a time span of several million years. Although not abundantly fossiliferous, the marine strata do contain calcareous concretionary lenses which often yield many well- preserved, large pelecypod shells (clams and oysters), and which occasion- , ally yield beautiful coiled ammonoid cephalopod fossils, some of which reach a diameter of more than four feet. Rarely, skeletons of marine rep- tiles, such as Ichthyosaurs and Mosasaurs, are found in Cretaceous marine strata of the Western Interior, although such finds are not known from the project area. The Tertiary Brown~' Park Formation underlies a large portion of the areas to be inundated by the two reservoirs of the Juniper - Cross Mountain Project, ---. "--------- --~--_.