How the Giant "Cosmic Navel" Formed in Utah

The unique landform in Grand Staircase-Escalante National Monument is essentially one of the biggest potholes on Earth

The Cosmic Navel is larger than it appears in this image—it spans about 200 feet wide and is between 16 and 65 feet deep. (courtesy of Flickr user John Fowler)
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With his latest work, photographer John Fowler brings a whole new meaning to the term "navel gazing." This mosaic image, captured in late April, showcases a unique landform sometimes known colloquially as the Cosmic Navel—essentially a giant sandy pothole in Utah's Grand Staircase-Escalante National Monument.

Such weathering pits have formed in various locations across southern Utah, carved into the region's Jurassic-era sandstone. Most are tens of feet wide, making them the largest cylindrical weathering pits on Earth. The Cosmic Navel stands out in part due to its unusual size—at almost 200 feet wide, you could comfortably nestle the Statue of Liberty, sans base and laying sideways, inside the oval depression. The Navel also features a rock pedestal that towers about 33 feet over a rusty-hued sand dune, earning the pit its other popular nickname: the Cosmic Ashtray.

"Geologists have known about this for some time, and it even took us a while before we wrote it up," says geology professor Marjorie Chan of the University of Utah, who co-authored a 2008 paper describing the pit. The landform goes by a handful of colorful monikers, and "Cosmic Navel seems to be a name that popped up recently," she adds. So how did this geologic bellybutton form high on the summit of a sandstone dome? Oddly enough, it probably exists because a river once ran through it, says John Bartley, chair of the geology and geophysics department at the University of Utah.

"This landform … was almost certainly produced by erosion by a meandering river, probably deepened somewhat by later wind erosion," Bartley says. "Compare it to the goosenecks of the San Juan River. Imagine what would the result would be if the ridge in the middle of one of the loops were breached—what is now a ridge would become a central peak isolated by river erosion."

Weathering pits can be tough to age, but based on the rate of erosion in rocks around the Colorado River, geologists think the Cosmic Navel may be up to 216,000 years old. Over time, strong winds have sandblasted the pit, widening it and sculpting the walls and floor. Even today, the striking orange dune inside the pit is always shifting under the powerful desert winds, according the 2008 analysis by Chan and Dennis Netoff of Sam Houston State University in Texas.

"The pit-floor dune changes shape, height and position constantly, perhaps with every strong wind event," the researchers write. "At times, it completely covers the bedrock floor of the pit, whereas at other times bedrock is well-exposed." While they estimate that the sand can get up to 26 feet deep, they found that most of the material isn't coming from erosion of the pit itself. Samples show that most of the light, fine-grained sand blasted off the pit walls gets wafted away, and the courser sand in the dune is probably being blown in from elsewhere in the region.

The team notes that the Navel is also intriguing because it showcases a wide diversity of wind-carved rock features. For instance, wind action has created sharp sets of finger-shaped projections in the sandstone called dedos, which are partially shielded from erosion by iron concretions in the rock wall. The features resemble the iron-rich "blueberry" spherules seen on Mars by the Opportunity rover, the team says, hinting that further study of the Navel could help geologists figure out how the mysterious blueberries formed and maybe even help decipher ancient Martian wind patterns.

"The shape and orientation of the dedos can be used to interpret the direction and strength of strong, sand-moving winds on Earth and Mars," they write. But anyone hoping to get a better look at the Cosmic Navel better be prepared for an adventure—the landform is about 14 miles from the nearest town, deep in the arid national monument. To snap this shot, Fowler drove several miles down a rough dirt road, took a four-mile hike, scaled a 500-foot rock face and spent a night alone under the stars.

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About Victoria Jaggard

Victoria Jaggard is the science editor for Smithsonian.com. Her writing has appeared in Chemical & Engineering News, National Geographic, New Scientist and elsewhere.

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