The rocks exposed in Bryce Canyon are about 100 million years younger than those in nearby Zion National Park. Bryce Canyon’s formations are the youngest known units in the Grand Staircase. Abundant amounts of petrified wood, oyster beds containing millions of fossils, and coal are all found in the Dakota Sandstone.
About Geology of the Bryce Canyon area in brief
The rocks exposed in Bryce Canyon are about 100 million years younger than those in nearby Zion National Park. Bryce Canyon’s formations are the youngest known units in the Grand Staircase. In the Cretaceous, a shallow seaway spread into the interior of North America from the Gulf of Mexico in the south into Utah and later to the Arctic Ocean in the far north. Abundant amounts of petrified wood, oyster beds containing millions of fossils, and coal are all found in the Dakota Sandstone. The Tropic Shale is perhaps the most fossil-rich formation in the Bryce Canyon area. It sits unconformably on much older Jurassic formations that are not exposed in the immediate area. Mud and silt were deposited on top of the seaway as the seaways became deeper and calmer in the area. The resulting transgression records the maximum transgression into the Utah and is 1,000 feet thick in the Paria Amphitheater. It forms the badlands seen in the Tropic Valley and the Claron Formation that dominates the park’s amphitheaters. Its members represent various stages in this process in which sediment was deposited. The cliff-forming sandstone of the Tibbet Canyon Member was conformably deposited on the top of shallow marine and later marine environments. It was deposited in the warm shallow sea and the cool streams and lakes that contributed sediment to the colorful Claron formation. 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 of Bryce Canyon. The oldest members of this supersequence of rock units are exposed in Grand Canyon, the intermediate ones in Zion, and its youngest parts are laid bare in Bryce canyon area. There are, however, shared rock units between all three, creating a super sequence of formations that geologists call theGrand Staircases. The formations of the GrandStaircase record nearly 2000 million years of the Earth’s history. They are part of the U.S. Geological Survey’s “Geologic Time Series” (GTS) which includes the Grand Canyon and Zion National Parks. The GTS covers the last half of the Cenozoic era and the first half of that era in that part of North American. It also includes the Jurassic period and the early Pleistocene period. It is the largest GTS area in the United States, covering an area of more than 1.5 million square miles (3.6 million km2) and stretching from New Mexico to California. It includes the Colorado River and its tributaries, including the paria River, which is eroding headward in between two plateaus adjacent to the park. The rocks exposed at Bryce Canyon and the Zion and Kolob canyons area to the southwest are called the “Bryce Canyon Formation” and the “Kolob Formation”
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This page is based on the article Geology of the Bryce Canyon area published in Wikipedia (as of Nov. 03, 2020) and was automatically summarized using artificial intelligence.
