Bryce Canyon geology

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The exposed geology of Bryce Canyon shows a series of deposits that cover the last section of the Cretaceous and the first half of the Cenozoic in this part of North America . The former sedimentation area of the present Bryce Canyon National Park ranges from the warm shallow sea, in which the Dakota sandstone and tropic shale were deposited, to the cold rivers and lakes of the now colorful Claron Formation , the amphitheater- like semicircle of the park controlled.

Further layers formed, but most of them have been removed again, as two periods of uplift followed, one about 70 million years ago, which was the cause of the formation of the Rocky Mountains , and the other 10 to 15 million years ago. Years that the Colorado Plateau produced . The uplift created vertical fractures that were increasingly eroded much later, forming freestanding battlements , badlands, and monoliths . These special formations in the park are part of the Grand Staircase .

Valley in Bryce Canyon

The Grand Staircase

Grand Canyon (A), Chocolate Cliffs (B), Vermilion Cliffs (C), White Cliffs (D), Zion Canyon (E), Gray Cliffs (F), Pink Cliffs (G), Bryce Canyon (H)

The exposed rocks in Bryce Canyon are about 100 million years younger than those in neighboring Zion National Park , and they are younger than those in the Grand Canyon further south . However, all three locations belong to a common series of rocks - a long sequence known to geologists as the Grand Staircase. Overall, the Grand Staircase documents almost 2 billion years of the earth's history . The Bryce Canyon formations are the youngest known steps on the Great Staircase. If there ever were younger rocks, they have been removed by erosion.

Sedimentation of the exposed rocks

Cretaceous sea passage and later

Cretaceous sea passage

The base of the Dakota sandstone consists of conglomerate and fossil-rich sandstone. This sequence was probably deposited later in the Cretaceous period in a shallow sea - referred to by geologists as the Cretaceous Seaway - which divided North America in a north-south direction. The Dakota sandstone is the oldest formation that is exposed in Bryce Canyon, but the youngest in the Zion area further south-west. In the area of ​​Bryce Canyon this formation can be seen in the Paria Valley , as a petrified sand cover, which was probably deposited on beaches , in lagoons and coal swamps during the transgression (sea encroaches on land) of the Cretaceous sea passage in this area .

The tropic shale was deposited as mud and silt in the same sea as it became deeper and therefore calmer. This series of rocks can be found in deeper sections of the park. It contains ammonites as fossils .

Sandy and clayey sediments such as the Straight Cliffs, Wahweap and Kaiparowits formations were deposited during the Cretaceous period, later lifted and partly eroded away again at the end of the geological era, so that they are now discordant . These rocks emerge in the southern part of the park at lower altitudes.

The uplift process took place during ore formation , the so-called Laramian orogeny , which lasted from the late Cretaceous to the early Paleocene . It pushed individual sections of the crust upwards, while lower areas of the pelvis gradually sank further.

Claron formation

Claron lake system

A vast network of shallow lakes, covering thousands of square kilometers , covered large parts of eastern and central Utah and southwestern Montana in the Eocene . Large amounts of lake sediment were deposited in this system in the 20 million years of its existence, about 63 to 40 million years ago. In the course of climatic changes, these lakes changed their dimensions over time - they expanded in periods of high rainfall and shrank in periods of low rainfall. These processes left deposits of varying thickness and composition, piled up around Bryce Canyon:

Pure lime sludge was deposited at the greatest depth. In shallower water, the transition to lime-rich mud, to lime-poor mud towards the shore and to various sands and gravel deposits near the shore took place.

These lake sediments were later petrified into a heterogeneous, fossil-poor mixture of limestone, marl (?), Sandstone and conglomerates, which now form the Claron Formation (formerly: Wasatch Formation). The geologist Clarence Dutton referred to the iron oxide-rich deeper part of the Claron because of its colorful appearance as the Pink Riffs series. The fragile peaks that Bryce Canyon is famous for, called hoodoos (bad luck charms), are almost entirely made up of these Claron layers. The elements of the White Cliff form monoliths. Most of the arches and natural bridges, including the famous Natural Bridge, were carved out of sandstone deposits in the Claron.

Colorado Plateau and Erosion

Map of the Colorado Plateau

Even younger rocks were formed by sedimentation , but mostly removed by subsequent erosion accelerated by uplift . These formations can be seen in the northern part of the park and in some places on the edge of the plateau. Among them are the 15 to 30 meter thick Boat Mesa conglomerate from the Oligocene , which is formed from erosion debris from the Claron, and, from the Pliocene to early Pleistocene , the Sevier River Formation made of gray-brownish sandstone with some conglomerates.

In the Miocene , around 16 million years ago, the Colorado Plateau was raised from almost sea level to over a kilometer. With this uplift tension forces were generated, which divided the region into different plateaus, such as the Paunsaugunt . The tension from Nevada to the west was so strong that the earth's crust was stretched, creating a series of basins and mountain ranges called the Basin and Range Province. As a result, the tension-induced reshaping of the Colorado Plateau was greatest on the western edge. Long faults such as Sevier and Paunsaugunt developed in a north-south direction .

Formation of hoodoos

As North America gradually drifted north, the climate cooled and became more humid. It is possible that erosion of the Paunsaugunt Plateau from above in the late Tertiary and early Quaternary periods created the "amphitheater" of Bryce Canyon. In contrast, different types of erosion and frost breakouts prepared the so-called hoodoos . During the ice ages in the Pleistocene, there was ice and snow all year round in the higher regions .


  • Geology of National Parks: Fifth Edition , Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall / Hunt Publishing; 1997) ISBN 0-7872-5353-7
  • Secrets in The Grand Canyon, Zion and Bryce Canyon National Parks: Third Edition , Lorraine Salem Tufts (North Palm Beach, Florida; National Photographic Collections; 1998) ISBN 0-9620255-3-4

Recommended literature

  • DeCourten, Frank. 1994. Shadows of Time, the Geology of Bryce Canyon National Park . Bryce Canyon Natural History Association.
  • Kiver, Eugene P., Harris, David V. 1999. Geology of US Parklands 5th ed . John Wiley & Sons, Inc.
  • Sprinkel, Douglas A., Chidsey, Thomas C. Jr., Anderson, Paul B. 2000. Geology of Utah's Parks and Monuments . Publishers Press