BRYCE CANYON GEOLOGY SEDIMENTATION LITHIFICATION UPLIFT EROSION
Bryce Canyon Geology
Nowhere else in the world can you find rock pinnacles with fantastic shapes like the ones found in Bryce Canyon National Park.
Located in the High Plateaus region of the Colorado Plateau in Utah, Bryce Canyon’s elevation, erosion, climate and rock type are all elements that, when combined, form fantastical shapes called Hoodoos.
Hoodoos Cast Their Spell
Hoodoo – a pillar of rock, usually of fantastic shape, left by erosion.
Hoodoo – to cast a spell.
Early Native Americans left little to tell us of their use of the plateaus. We know that people have been in the Colorado Plateau region for about 12,000 years, but only random fragments of worked stone tell of their presence near Bryce Canyon. Artifacts tell a more detailed story of use at lower elevations beyond the park’s boundary. Both Anasazi and Fremont influences are found near the park. The people of each culture left bits of a puzzle to be pieced together by present and future archaeologists. Paiutes lived in the region when Euro-Americans arrived in southern Utah. Paiutes explained the colorful hoodoos as “Legend People” who were turned to stone by Coyote.
The Paiutes were living throughout the area when Capt. Clarence E. Dutton explored here with John Wesley Powell in the 1870s. Many of today’s place names come from this time. Dutton’s report gave the name Pink Cliffs to the Claron Formation. Other names – Paunsaugunt, place or home of the beavers; Paria, muddy water or elk water; Panguitch, water or fish; and Yovimpa, point of pines – were derived from the Paiute language.
The Paiutes were displaced by emissaries of the LDS Church who developed the many small communities throughout Utah. Ebenezer Bryce aided in the settlement of southwestern Utah and northern Arizona. In 1875 he came to the Paria Valley to live and harvest timber from the plateau. Neighbors called the canyon behind his home Bryce’s Canyon. Today it remains the name not only of one canyon but also of a national park.
Shortly after 1900, visitors were coming to see the colorful geologic sights, and the first accommodations were built along the Paunsaugunt Plateau rim above Bryce’s Canyon. By 1920 efforts were started to set aside these scenic wonders. In 1923 President Warren G. Harding proclaimed part of the area as Bryce Canyon National Monument under the Powell (now Dixie) National Forest. In 1924 legislation was passed to establish the area as Utah National Park, but the provisions of this legislation were not met until 1928. Legislation was passed that year to change the name of the new park to Bryce Canyon National Park.
Each year the park is visited by more than 1.5 million visitors from all over the world. Open all year, the park offers recreational opportunities in each season. Hiking, sightseeing, and photography are the most popular summer activities. Spring and fall months offer greater solitude. In the winter months, quiet combines with the area’s best air quality for unparalleled views and serenity beyond compare. In all seasons fantastic shapes cast their spell to remind us of what we protect here in Bryce Canyon National Park.
Visitors at Bryce Canyon National Park come to see the unique shapes formed in the Claron Formation. Bulging spires and narrow rock fins fan out from the edge of the plateau. These rock spires and fins are commonly known as Hoodoos.
The chaotic destructive force of water, not wind, is responsible for the fantastic shapes in Bryce Canyon. Bryce Canyon Hoodoos formed over thousands of years by the same processes that form the features of surrounding parks.
Water, ice and gravity are the forces at work in Bryce Canyon National Park. These three forces coupled with the differential erosion of the Claron Formation produces a different morphology than that of any other area in the world.
10-15 million years ago the Paunsaugunt Plateau was caught and lifted by the Colorado Plateau. Breaks, called joints, formed in the plateau during the uplift. Joints allowed water to flow into the rock and, as water flowed through, erosion widened them into rivulets and gullies. Over time, deep slot canyons formed in the sides of the plateau.
Bryce Canyon receives an average rainfall of 10 inches a year in the valley and approximately 19 inches a year on the plateau. The majority of the precipitation falls in mid to late summer, as monsoons, usually in the afternoon. These thunderstorms can be fierce, dropping an inch or two of rain in under an hour and can often be accompanied by hail.
Because the soil at Bryce Canyon is very dry, only the top inch of soil absorbs rainfall before it starts to run off causing a treacherous flash flood. During a flash flood, rapidly moving water can carry rocks, tree limbs, and other debris which crashes into the canyon walls and congest passageways. Flash floods are a serious risk for the many explorers drawn to Bryce Canyon Country’s scenic slot canyons each year. Fortunately, flash floods can usually be avoided with common sense safety practices and an understanding of the conditions that cause them.
The Paunsaugunt Plateau receives approximately 100 inches of snowfall a year, which means that everyday a small amount of snow melts and runs into the joints and freezes at night. When water freezes it expands to form an ice wedge in the joint, widening the space. The ice wedge grows as more snow melts and freezes until finally, it breaks the rock.
Fragments of rock, from tiny pebbles to boulders as large as Volkswagens, fall from hoodoos and the sides of the Paunsaugunt Plateau by frost wedging and gravity. The smaller pieces are washed away by monsoons and snow melt while Boulders explode into cobble sized pieces on the canyon floor.
Limestone, siltstone, dolomite and mudstone make up the four different rock types that form the Claron Formation. Each rock type erodes at different rates which is what causes the undulating shapes of the hoodoos.
Limestone, siltstone and dolomite are very hard and form the protective caprock on most of the spires. These harder rocks are eroded predominantly by frost.
Mudstone is the softest rock in a hoodoo and is easily identified by the way it forms the narrowest portion of the pinnacles. As mudstone moistens it erodes easily and runs down the sides of the rock forming mud stucco as a protective coating. Every time it rains the layer of mud stucco is renewed. If wind does not erode the stucco layer fast enough it will renew before wind erosion affects the rock. For this reason, wind has little to no effect on hoodoo formation or destruction.
While visiting Bryce Canyon National Park look for signs of wind and water erosion. It is surprising how visible the numerous signs of water erosion are, when you know what to look for.
The Cretaceous Period began some 144 million years ago and lasted until about 63 million years ago. The rock formations you see exposed at Bryce Canyon began to develop during this time. For 60 million years a great seaway extended northwestward into this area, depositing sediments of varying thickness and composition as it repeatedly invaded, retreated, and then re-invaded the region. Retreating to the southeast, it left sediments thousands of feet thick. Their remnants form the oldest, lowest, gray-brown rocks at Bryce Canyon.
In the Tertiary Period, between 66 and 40 million years ago, highlands to the west eroded into shallow, broad basins. Iron-rich, limy sediments were deposited in the beds of a series of lakes and streams. These became the red rocks of the Claron Formation from which the hoodoos are carved and for which the Pink Cliffs are named.