The paradox of Lower Cretaceous gravels and the initiation of thrusting in the Sevier orogenic belt, United States Western Interior

Gravels of Early Cretaceous age that are widespread throughout much of the Western Interior are commonly assumed to have been deposited in a foreland basin adjacent to the Sevier thrust belt to the west. Synorogenic foreland conglomerates, however, are in most cases restricted to that part of the basin most proximal to the thrust system. In contrast, the Lower Cretaceous gravels of the Western Interior represent a widespread low-sinuosity stream system that deposited gravel more than 600 km from the closest possible site of thrusting. Although paleohydraulic calculations indicate that slopes on the order of only 1 m/km were needed to transport these gravels from the thrust belt, the results from flexural modeling indicate that even this slope could not have been sustained over great distances in a foreland basin adjacent to the Sevier belt. The gravel, therefore reflects regional uplift to the west and may not be directly associated with thrusting. -from Authors