page_title: Geology of the Bryce Canyon area
section_title: Formation of the High Plateaus
hierarchical_section_title: Geology of the Bryce Canyon area / Late Cenozoic tectonics / Formation of the High Plateaus
caption_attribution_description: English: Map of the Colorado Plateau — in the Western United States. Français&#160;: Carte du fr:Plateau du Colorado
context_page_description: The exposed geology of the Bryce Canyon area in Utah 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 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 sediment to the colorful Claron Formation that dominates the park's amphitheaters.
  Other formations were also formed but were mostly eroded following uplift from the Laramide orogeny which started around 70 million years ago. This event created the Rocky Mountains far to the east and helped to close the sea that covered the area. A large part of western North America started to stretch itself into the nearby Basin and Range topography around 15 mya. While not part of this region, the greater Bryce area was stretched into the High Plateaus by the same forces.
context_section_description: Younger rock units were laid down but were mostly removed by subsequent uplift-accelerated erosion. Outcrops of these formations can be found in the northern part of the park and in a few places on the plateau rim. Among these are the 50-to-100-foot (20 to 30 m) thick Oligocene or Miocene-aged Boat Mesa Conglomerate and the Pliocene to early Pleistocene-aged Sevier River Formation. The Boat Mesa is made mostly of conglomerates with minor amounts of sandstone and some limestone from lakes, representing stream and overbank flood deposits. The brownish-gray sandstone and gravels of the Sevier River Formation were laid down in valleys that were part of the ancestral Sevier River drainage system.
  Around 15 mya in Miocene time, tensional forces in Nevada to the west were so great that the crust was spread thin, creating the Basin and Range Province. These same forces segmented what is now the western part of the Colorado Plateau into nine different smaller plateaus, including the Paunsaugunt that the park sits astride. Long, north–south-trending normal faults were either newly created or reactivated from older pre-existing faults; a plateau rose on one side of each fault while valleys subsided on the other as the crust was extended in an east-west direction.  Two of these faults bound the Paunsaugunt Plateau; the Sevier on the west and the Paunsaugunt on the east. Movement along these two faults has displaced the Claron Formation by 2,000 feet (600 m) relative to the Paria and Sevier valleys.
  The Hurricane Fault marks the west edge of the Markagunt Plateau and is the topographic boundary between the Basin and Range and the Colorado Plateaus provinces. Cedar Breaks National Monument, which shares almost the same exposed geology and erosional features as Bryce Canyon National Park, sits on the west edge of the Markagunt.
  The entire Colorado Plateau then started to uplift from near sea level to several thousand feet (over a kilometer) in elevation. An alternate theory is that the Laramide orogeny uplifted what is today the Basin and Range and the Colorado Plateau and that the tensional forces that formed the Basin and Range caused that region to subside relative to the Colorado Plateau. Whatever the order of events were, the High Plateaus region of the Colorado Plateau were by now nearly complete.
caption: Colorado Plateaus map
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