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Sand Pipes, Craters & Dunes: Southern Utah’s Geology is More than Just Arches

Sand Pipes, Craters & Dunes: Southern Utah’s Geology is More than Just Arches

Written By Laurie J. Schmidt

Capitol Reef National Park | More Than Just Parks

If you were asked to name the most striking geologic formations in Southern Utah, your answer might be Delicate Arch or the tangerine-colored hoodoos at Bryce Canyon. Or maybe the skyscraping walls of Zion Canyon. There’s no doubt these dramatic sites draw visitors from around the world. But as one of the most geology-rich states in the U.S., Utah has many less-famous geologic treasures that are often overlooked.

Fisher Towers

Outdoor enthusiasts flock to Moab to see Arches and Canyonlands national parks, but just a few miles away is one of the most photographed scenes in Utah: Fisher Towers framed by the La Sal Mountains. These monolithic sandstone pinnacles are the remnants of a floodplain that was deposited from the Rocky Mountains about 225 million years ago. Erosion gradually wore away the softer layers of sandstone, leaving the more resistant rock that makes up the towers. The tallest of the towers, the Titan, stands 900 feet high and is said to be the largest freestanding rock tower in the U.S.

Huntley Ingalls, part of the first climbing team to ascend the Titan, described Fisher Towers as “a pink, red and orange skyscraper city.” One of the most striking things about the spires is their drapery-like appearance, created when rainwater drained down the sandstone over millions of years and left vertical gulleys.

Even today, erosion and weathering processes continue to chisel away at Fisher Towers. Evidence of their fragility came in 2014 when a 40-foot tower capped by a rock that resembled the head of a snake, called the Cobra, toppled over after a heavy rainstorm.

You can wander among the tall spires by taking the 4.6-mile (out-and-back) Fisher Towers Trail, which winds along the base of the towers. Fisher Towers is a world-famous climbing destination, so hikers should be cautious of falling rock near popular climbing routes.

Fisher Towers are the remnants of a floodplain deposited from a region of geologic uplift in western Colorado.

Photo: Marc Piscotty

Upheaval Dome

Imagine riding across the Utah desert on horseback and suddenly finding yourself at the edge of a 1,000-foot drop-off. The first explorers to reach the rim of Upheaval Dome must have come to a jolting halt. Smack dab in the middle of the sandstone rock layers is a colossal crater about three miles wide.

Upheaval Dome sits on top of a high mesa called Island in the Sky in Canyonlands National Park. Known as a geologic anomaly, the dome deviates significantly from other structures in the surrounding area. Throughout the Island in the Sky District, rock formations appear in a layered structure, evidence that they were uniformly exposed as the Colorado and Green Rivers cut through the mesa. But at Upheaval Dome, this geologic pattern is suddenly disrupted, and rocks that were once buried underground are now exposed at the surface. But the real intrigue of Upheaval Dome lies in the enigma of its origin.

Upheaval Dome was first studied about 100 years ago; in the decades that followed, geologists debated two theories about the structure’s origin. According to the first theory, the crater resulted from a meteorite impact during the Jurassic Period. The resulting explosion caused the rocks at the bottom of the crater to push upward to fill in the hole left by the blast.

At Upheaval Dome, rocks that were once buried a mile underground are now exposed at the surface in the crater.

Photo: Laurie Schmidt

The second explanation is how Upheaval Dome got its name: the salt dome theory. Millions of years ago, the Colorado Plateau was covered by a shallow sea. As the climate became drier, the seas dried up and left behind a thick layer of salt. Because salt is viscous over geologic timescales, it eventually flowed upward into the rock layers above, creating a structural dome.

A turning point came in 2008, when German researchers discovered “shocked quartz” in the brown-colored layer around the rim of the crater. Shocked quartz—sand grains that have a deformed structure caused by intense pressure—can only form as the result of an impact event or nuclear explosion. The meteorite impact theory became widely accepted as the correct one, although some scientists still support the salt dome idea. Moab resident Nathaniel Clark, a former ranger at Island in the Sky, says, “We now know so much about the geology of this landscape, but I kind of like that there’s this huge hole in the ground here that’s still a mystery.”

The Upheaval Dome Trail leads to two overlooks of the crater (.8 miles and 1.8 miles roundtrip). On the way, you’ll pass a spur trail that leads to the Syncline Loop, a challenging 8-mile hike in rugged terrain. According to park rangers, more people require rescue on the Syncline Loop than in any other place in Canyonlands National Park. Exercise extreme caution if attempting this hike.

Raplee Ridge

Heading towards Monument Valley on U.S. Route 163, you get a front-row seat for one of the most striking geologic features in the southwest. On the south side of the highway is a multi-colored formation with rock layers in a V-shaped pattern. Raplee Ridge is a fold in the earth’s crust caused by tectonic stresses that pushed the rock layers upward, leaving a ridge that slopes downward to the San Juan River. Although commonly called Raplee Anticline, geologists say the ridge is technically a monocline, due to its step-like folds where the rock layers bend in one direction.

The triangular pattern of the ridge’s sandstone layers resembles the zig-zag geometric design often seen in Navajo blankets and rugs. The best time to see Raplee Ridge is during golden hour just before sunset, when the sun’s low angle lights up the side of the formation facing the highway. (Read: Finding Winter Solitude in Bluff)

Raplee Ridge is a fold in the earth’s crust caused by tectonic stresses that occurred millions of years ago.

Photo: Laurie Schmidt

Coral Pink Sand Dunes

Sand dunes probably aren’t on the list of geologic features most people expect to find in Southern Utah. But just 20 miles from the town of Kanab lies more than 3,000 acres of pink-colored dunes at Coral Pink Sand Dunes State Park. Formed when the Navajo Sandstone (the most prominent rock layer in Southern Utah) eroded over millions of years, the dunes are constantly on the move, shifting as much as 50 feet per year. The pink color comes from hematite, the same mineral that gives rust its reddish color.

Park visitors can experience the dunes via hiking, sandsledding (you can rent sleds at the visitor center) and ATV riding. It’s also a popular spot for photographers wishing to capture dramatic sunsets against the backdrop of the dunes. Roam Outdoor Adventure Co. and Coral Pink ATV Tours offer guided trips that include ATV/UTV tours and sand surfing.

The dunes were formed by the continual erosion of the nearby Navajo sandstone cliffs.

Photo: Andrew Dash Gillman

Kodachrome Basin State Park

Bryce Canyon National Park sees more than two million visitors each year, but only a fraction of them visit nearby Kodachrome Basin State Park. What they’re missing out on is seeing a geologic rarity: sand pipes. These massive freestanding rock spires are believed to the solidified remains of sediment that once filled ancient geysers. More than 60 sand pipes have been identified within the park, ranging from smaller ones less than 10 feet tall to the 172-foot-high Chimney Rock.

Kodachrome Basin got its name after a National Geographic Society expedition photographed the area in the late 1940s. They found the area’s colorful features to be so photogenic that they named it after Kodak’s once-popular color slide film. You’ll find several hiking trails here, including the Angel’s Palace Trail, a 1.5-mile loop hike that provides good views of the sand pipes from a high ledge.

These massive freestanding rock spires are believed to the solidified remains of sediment that once filled ancient geysers.

Photo: Laurie Schmidt

The Waterpocket Fold

Sometimes called the “backbone of Capitol Reef National Park,” the Waterpocket Fold stretches for about 100 miles from the park’s northern boundary south to Lake Powell. This gigantic warp in the earth’s crust is a classic example of a monocline, a single (mono) fold in an area of otherwise horizontal rock strata. The formation got its name from the many potholes, or waterpockets, that temporarily hold water after significant rain and snow events. Early settlers referred to the Waterpocket Fold as “the reef,” because it acted as a barrier to travel, just like an ocean reef.

Within the walls of the Waterpocket Fold, erosion has created a labyrinth of slot canyons, potholes and Swiss cheese-like holes in the sandstone. Several hiking routes in Capitol Reef cut through the Fold, including Grand Wash and Capitol Gorge. Taking a short walk on one of these trails allows you to get a closeup look at the inner canyons. Both of these routes follow washes, which are prone to flash flooding during monsoon season. Stop at the visitor center to check weather conditions before proceeding on these hikes. (Read: A Guided Adventure for Everyone in Utah's National Parks)

Capitol Reef is defined by The Waterpocket Fold, a 100-mile wrinkle in the Earth’s crust that runs all the way from the park’s northern boundary south to Lake Powell.

Photo: Matt Morgan

Bonus Site: Cathedral Valley Loop (off-road route)

Much of Capitol Reef National Park is accessible from Utah State Route 24 and the paved Scenic Drive. But in the far north section of the park lies Cathedral Valley, a remote desert that includes several unique geologic sites. (Read: Serenity Found in Torrey and Capitol Reef’s Cathedral Valley District)

The 58-mile unpaved route through Cathedral Valley requires high-clearance 4WD vehicles and includes fording the Fremont River at the beginning of the trip. Due to the area’s remote location and road conditions that can change rapidly, guided trips are recommended. Full-day trips are available with Capitol Reef Outfitters in Torrey. For experienced off-road drivers who wish to do a self-guided tour, Thousand Lakes RV Park offers jeep rentals. Below are some of the features you’ll spot along the loop.

Bentonite Hills

If you frequent social media, you’ve probably seen photos of the Bentonite Hills. These huge mounds are made of bentonite clay formed during the Jurassic Period when mud and volcanic ash were deposited in swamps and lakes. Minerals in the clay, including hematite and manganese, give the hills a colorful banded appearance in shades of brown, red, gray and green. Colors are most visible around sunset (note that many of the photos on social media are highly saturated). No trails exist through the Bentonite Hills. The fragile surface is easily damaged by footprints and tire tracks. Visitors must stay on roads and limit walking to firm areas and wash bottoms.

These huge mounds are made of bentonite clay formed during the Jurassic Period when mud and volcanic ash were deposited in swamps and lakes.

Photo: Laurie Schmidt

Gypsum Sinkhole

At nearly 50 feet in diameter and 200 feet deep, this deep hole developed when groundwater dissolved a buried gypsum plug. The void left by the gypsum then collapsed under the weight of rock layers above. There is no barrier fence around the formation. Visitors should stay away from the edge of the sinkhole as the rocks are very unstable and could collapse at any time.

At nearly 50 feet in diameter and 200 feet deep, this deep hole developed when groundwater dissolved a buried gypsum plug.

Photo: Laurie Schmidt

Temple of the Sun and Moon

Composed of the fine grains of the Entrada Sandstone, the Temples of the Sun and Moon are a striking example of erosion creating works of art. These two monumental formations are impressive not only due to their size, but also because they stand in stark contrast to the surrounding flat landscape. The freestanding Temple of the Sun towers more than 400 feet above the ground.

The monoliths are composed of buff-pink Entrada Sandstone deposited 160 million years ago during the Jurassic period.

Photo: Tom Till

Glass Mountain

Sitting in the shadow of the Temple of the Sun and Moon is a rounded pile of rock that seems to shimmer in the sunlight. About 165 million years ago, a crystalline variety of the mineral gypsum, called selenite, was deposited throughout this region when ancient seas evaporated. At Glass Mountain, these gypsum crystals have formed a mound that stands 15 feet high. While the rock is beautiful, visitors are reminded that collecting of any kind is prohibited in all national parks.

About 165 million years ago, a crystalline variety of the mineral gypsum, called selenite, was deposited throughout this region when ancient seas evaporated.

Photo: Laurie Schmidt

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About the Author – Laurie J. Schmidt

Laurie J. Schmidt is a writer and guidebook author who specializes in travel and environment. She has been hiking and photographing Utah's canyon country for more than 25 years.