Portal:Utah/Selected article/3
The exposed geology of the Bryce Canyon area shows a record of deposition that covers the last part of the Cretaceous Period and the first half of the Cenozoic era in that part of what is now North America. The ancient depositional environment of the region around what is now Bryce Canyon National Park varied from the warm shallow sea in which the Dakota Sandstone and the Tropic Shale were deposited to the cool streams and lakes that contributed to the colorful Claron Formation that dominates the park's amphitheaters.
Other formations were also created but were mostly eroded following two major periods of uplift; one around 70 million years ago (creating the Rocky Mountains) and another 10 to 15 million years ago (creating the Colorado Plateaus). The uplift caused vertical joints to form which were much later preferentially eroded to form the free-standing pinnacles, badlands, and monoliths we see today. The formations exposed in the park are part of the Grand Staircase. (Full article...)