Category: Geology

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The Dynamic History of Arches

The Dynamic History of Arches: Utah's Delicate Arch, Photo Courtesy and Copyright Mark Larese-Casanova
Utah’s Delicate Arch
Photo Courtesy & Copyright
Mark Larese-Casanova

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

The Dynamic History of Arches

A “bow-legged pair of petrified cowboy chaps” is how Edward Abbey once described Delicate Arch, that timeless example of Utah’s peculiar geology. In fact, it’s become such an icon that we see it on automobile license plates throughout the state. What we might not realize, though, is that there is nothing ‘timeless’ about Utah’s arches at all.

To help us understand this, let’s go back in time about 300 million years ago. At that time, inland seas routinely flowed into eastern Utah and evaporated, leaving behind a layer of salt that, in some places, is thousands of feet thick. During the next 200 million years, winds, oceans, and rivers deposited a rainbow of sediment layers in southern Utah. These sediments were eventually cemented into sandstones, limestones, and other sedimentary rocks.

Dynamic History of Arches: How nature builds an arch, Graphic Courtesy US National Parks Service
Click Graphic to
Learn How Nature Builds an Arch
Graphic Courtesy
US National Parks Service

Under the weight of all of these rock layers, along with the gradual uplift of the Colorado Plateau around 10 million years ago, the unstable salt layer below flowed like toothpaste. This caused the rock layers above to shift and buckle. Think of it as trying to build a brick house on top of a bed of mud- you would eventually have a house full of cracks.

In some areas, many parallel cracks formed at the surface, and as water flowed into these cracks, the sandstone eroded into tall vertical fins. Some of the fins collapsed over time, and some eroded in just the right way to form an arch. Arches continue to erode and will eventually collapse. But, at the same time, new arches will always form.

There are over 2,000 catalogued arches just within Arches National Park. That’s a lot of arches within such a small area! Within the park, most of the arches have formed in the red, iron-rich Entrada sandstone, however the tan Navajo sandstone also has several. Other rock formations to be seen include spires, mesas, windows, natural bridges, and balanced rocks.

To learn more about Utah’s amazing geologic history, visit Arches National Park’s website at nps.gov/arch or the Utah Geological Survey’s website at geology.utah.gov. And, make sure to visit and explore Utah’s arches as often as you can. After all, they won’t be around forever…

For Wild About Utah, I’m Mark Larese-Casanova.
Credits:

Images: Courtesy US National Parks Service

Delicate Arch, Courtesy & Copyright Mark Larese-Casanova

Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Desert Solitaire, Edward Abbey, https://www.amazon.com/Desert-Solitaire-Edward-Abbey/dp/0671695886

Arches National Park, US National Park Service, US Department of the Interior, www.nps.gov/arch/

Utah Geological Survey, State of Utah, www.geology.utah.gov

 

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The Sistine Chapel in Utah

The Sistine Chapel in Utah
Holy Ghost group, part of the
Great Gallery in Horseshoe Canyon
Photo Courtesy
David Sucec, BCSProject
(photographer, copyright holder)

Utah is famous for the beautiful and mysterious rock art found on its colorful canyon walls.

There are two main types of rock art. A petroglyph is an image that is pecked, incised, or scratched into rock. Petroglyphs are often found on rock surfaces coated with desert varnish. The dark stained varnish provides high contrast as the image is carved into the lighter underlying stone.

Pictographs, however, are painted onto rather than carved into a rock surface. Mineral pigments such as hematite, limonite, azurite, and gypsum were used to produce long lasting liquid and solid paints. Paint was applied with brushes, fingertips or hands, with fiber wads and even by spraying or blowing paint. It’s possible that vegetable dyes were also used by ancient artists but these would have been washed away without leaving a trace.

Archaeologists classify ancient rock art into different styles according to image content, drawing techniques, location, and the relationships between various picture elements. The so-called Barrier Canyon Style is well-known in eastern Utah where its greatest level of expression is found.

The Barrier Canyon Style features human-like figures with a supernatural appearance. Torso lengths are exaggerated and shaped like mummys or bottles. Heads may have horns, rabbitlike ears or antennalike projections. Eyes of the figures are often round and staring. Hands, if present, may be holding plant-like images or snakes. Aside from the human-like figures, birds, canines, bighorn sheep, and rabbits are also common in Barrier Canyon Style compositions.

Cultural affiliations of the Barrier Canyon Style artists are still not fully understood. But most archeaologists agree that the artists were part of small bands of nomadic people who roamed the Colorado Plateau between 7500 BC and 300 AD.

Perhaps the best place to view the Barrier Canyon style is in the Great Gallery in Horseshoe Canyon near Canyonlands National Park. The Great Gallery features a 300 feet long mural with over 60 figures. David Sucec (pronounced Soosek)–who is coordinating an effort to photograph and record all Barrier Canyon Style rock art–calls the Great Gallery ‘Utah’s Sistine Chapel.’

So far over 230 different sites featuring Barrier Canyon Style rock art have been discovered. In Utah, look for them in the Book Cliffs area, the San Rafael Swell, around Moab and in Canyonlands National Park.

Thanks to the Red Cliffs Lodge in Moab, Utah for supporting research and development of this Wild About Utah topic.

For Wild About Utah, I’m Holly Strand.

Credits:

Images: Courtesy & Copyright David Sucec
Text:     Holly Strand, Stokes Nature Center

Sources & Additional Reading:

BCSProject. https://www.bcsproject.org/about.html

Cole, Sally. 1990. Legacy on Stone: Rock Art of the Colorado Plateau and Four Corners Region. Boulder, CO: Johnson Printing

Repanshek, Kurt. Traces of a Lost People. 2005. Smithsonian magazine. March 2005. https://www.smithsonianmag.com/people-places/lost.html

Schaafsma, Polly. The Rock Art of Utah. 1971, Third Printing 1987, Papers of the Peabody Museum of Archaeology and Ethnology Vol. 65, paper, 169 pp. https://www.amazon.com/Rock-Art-Utah-Polly-Schaafsma/dp/0874804353

Take the Pledge to Protect the Past, Utah State Historical Preservation Office, Department of Cultural & Community Engagement, State of Utah, https://ushpo.utah.gov/shpo/upan/

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Utah, the Red State

Utah, the Red State
Chinese Wall at Bryce Canyon National Park
Courtesy National Parks Service
Hi, I’m Holly Strand for Wild About Utah

Straddling the four corners region is a massive geologic province known as the Colorado Plateau. Varying from 5 to 10,000 feet in elevation the region covers an area even larger than Utah, and is composed of thick horizontal layers of sedimentary rock. Wind and water have whittled Plateau rock into dramatic cliffs and steps as well as fanciful domes, towers, turrets, and arches. A predominance of red bed deposits in the central area of the Plateau has prompted the nickname “red rock country.”

So what’s behind these spectacular red hues? The color of rock is primarily influenced by trace minerals. The red, brown, and yellow colors so prevalent here result from the presence of oxidized iron–that is iron that has undergone a chemical reaction upon exposure to air or oxygenated water. The iron oxides released from this process form a coating on the surface of the rock or rock grains containing the iron.

Utah, the Red State: Entrada sandstone is responsible for some of the reddish rock found in Arches National Park. Photo Courtesy USGS
Entrada sandstone is responsible
for some of the reddish rock found
in Arches National Park.
Courtesy USGS

Just think of what happens to a nail when you leave it outside. Upon prolonged exposure, the iron in the nail oxidizes and rust is formed as a coating on the surface of the nail. So basically what we have in red rock country is a lot of rusting sandstones and shales. Hematite is an especially common mineral form of iron oxide in Utah, the name coming from the Greek word “heama” or red blood. It only takes a tiny bit of hematite make a lot of red rock.

Certain rock formations in Utah are particularly well-known for their beautiful reddish colors. The Permian Period gave us Organ Rock shale which caps the buttes and pinnacles of Monument Valley. The deep ruddy browns of the Moenkopi formation were formed in the Triassic. In the early Jurassic, eastern Utah was a vast sea of sand with wind-blown dunes. These dunes became the red bed deposits of the Wingate Formation which today forms massive vertical cliffs. Entrada sandstone, from the late Jurassic, forms the spectacular red, slickrock around Moab.

Reddish brown Moenkopi Formation in Capitol Reef National Park, Photo Courtesy USGS
Reddish brown Moenkopi Formation
in Capitol Reef National Park.
Courtesy USGS

So now you know what I’m thinking of when I hear Utah referred to as a Red State. I’m picturing the extraordinary splendor of the red, orange and rust- brown rocks that help to form the massive geologic layer cake in the south and east of our state.

For Wild About Utah I’m Holly Strand.

Utah, the Red State-Credits:

Photos: Courtesy National Park Service, https://www.nps.gov/brca/ and

United States Geological Survey (USGS), https://www.usgs.gov/

Text & Voice: Holly Strand

Utah, the Red State-Additional Reading:

Discover additional Wild About Utah pieces authored and voiced by Holly Strand, https://wildaboututah.org/author/holly-strand/

Chan,Marjorie A. and William T. Parry Rainbow of Rocks . Public Information Series 77. Utah Geological Survey. https://ugspub.nr.utah.gov/publications/public_information/pi-77.pdf [Accessed August 2025]

Geology Underfoot in Southern Utah by Richard L. Orndorff, Robert W. Wieder, and David G. Futey, Missoula, MT Mountain Press Publishing Company, 2006, https://mountain-press.com/products/geology-underfoot-in-southern-utah

Chronic, Halka. Roadside Geology of Utah. Missoula, MT Mountain Press Publishing Company, 1990 https://mountain-press.com/products/roadside-geology-utah

Fillmore, Robert, The Geology of the Parks, Monuments and Wildlands of Southern Utah, University of Utah Press, 2000, https://uofupress.com/books/geology-of-parks-monuments-and-wildlands-of-southern-utah/

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Last Blank Spots on the Map

Audio:  mp3 Listen to WildAboutUtah

Today the river corridor still retains
its wild and pristine qualities.
Copyright 2009 Dan Miller from the book
The River Knows Everything

Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

The Green River is one of Utah’s signature waterways. It begins high in Wyoming’s Wind River Range and winds southward 730 miles to join the Colorado River in Canyonlands National Park. 60% of river’s extent lies in Utah– attracting river runners, archaeologists, fishermen, hunters and hikers. And of course, geologists.

Desolation boasts steep dramatic walls.
From the top of the Tavaputs Plateau to the river
is deeper than the Grand Canyon.
Click to view larger image,
Photo Copyright 2009 Dan Miller

It’s hard to believe that less than 150 years ago, most of the Green and the Colorado canyonlands were unlined areas marked “UNEXPLORED” on maps. One such place was the area between Uinta Valley and Gunnison’s Crossing — now called Green River, UT. Another blank spot lay south of the crossing all the way to Paria which is now called Lee’s Ferry in Arizona.

To some folks, a blank spot on a map is an irresistible call to come and see what’s there. So it was with John Wesley Powell, a one-armed Civil War veteran working as a curator in a small natural history museum in Illinois. He became intrigued with exploring the canyons of the Colorado and the Green after spending some time out west collecting rock samples.

Lighthouse Rock 1871
Courtesy Arizona Historical Society

Impatient for adventure and discovery, Powell quickly assembled a crew of nine men –mostly rough and tumble mountain men used to living off the land. They set off from Green River WY and were making good time until disaster struck in the Canyon of Lodore. One of the boats hit a boulder, and a third of the food and half of the cooking gear sunk to the bottom of the river. A week later, a fire destroyed more food and gear. But eventually, five of the original nine made it all the way to the mouth of the Virgin River in Arizona.

A second expedition benefited from more funding, planning and hindsight. This time round, Powell chose a more scientifically-minded crew including a geologist, cartographer and photographer to research and document the trip. Once again they launched from Green River, WY. Powell perched in an armchair strapped to the middle bulkhead of a boat named after his wife, the Emma Dean . He read poetry to the crew as they floated along calm stretches of the river. The crew ran the Green and then started down the Colorado without any major incidents. After overwintering on the north rim, they ran the rapids of the Grand Canyon in late summer of the following year.

John Wesley Powell with Tau-gu
a Paiute, 1871-1872
Courtesy Arizona Historical Society

Upon return, surveyor Alven Thompson completed a topographic map of the region, and Powell’s monumental account was published in 1875 by the Smithsonian Institution.

The last “UNEXPLORED”s on the United States map were now replaced by specific landscape features with measured altitudes. Nowadays we still use the many evocative names that Powell and his men bestowed during their travels. Names like Flaming Gorge, Glen Canyon, Dirty Devil River, Escalante River, Cataract Canyon, and Desolation Canyon tell us something of the experiences of these brave men as they were exploring Utah’s last mysterious places.

Thanks to the Rocky Mountain Power Foundation for supporting research and development of this Wild About Utah topic.

Additional thanks to Rey Lloyd Hatt and the friendly staff of the John Wesley Powell River History Museum in Green River UT.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.
Credits:

Images: Copyright Dan Miller from the book
The River Knows Everything: Desolation Canyon and the Green

Powell images: Courtesy Arizona Historical Society

Text:     Holly Strand, Stokes Nature Center

Sources & Additional Reading

Aton, James M. and Dan Miller (photographer) 2009. The River Knows Everything: Desolation Canyon and the Green. Logan: Utah State University Press.

https://www.usu.edu/usupress/books/index.cfm?isbn=6523

Stegner, Wallace. “ Green River: The Gateway” in Blackstock, Alan. 2005. A Green River reader. Salt Lake City: University Utah Press.
https://www.amazon.com/Green-River-Reader-Alan-Blackstock/dp/0874808375

John Wesley Powell River History Museum in Green River UT https://johnwesleypowell.com/

USGS. 1976. Geological Survey Information 74-24. John Wesley Powell: Soldier, Explorer, Scientist.
https://www.nps.gov/history/history/online_books/geology/publications/inf/74-24/index.htm [Accessed October 30 2009]