High on the summit of a sandstone dome in Grand Staircase-Escalante National Monument sits a giant geologic bellybutton – and researchers say it may hold clues to ancient Martian wind patterns.
Across southern Utah’s Jurassic-era sandstone are some remarkable geologic divots known as weathering pits – depressed, erosional feature found on flat or gently sloping rock. But while most weathering pits are in the range of tens of feet wide, a handful of giant ones have developed in this stretch of Utah on outcrops of barren, friable Navajo sandstones. They are among the largest cylindrical weathering pits on Earth.
The most remarkable of these is colloquially known as the Cosmic Navel. At almost 200 feet wide, one could comfortably wedge the Statue of Liberty on her side within, observes Smithsonian Magazine. Also adding to the spectacle is the rock pedestal that juts up from the center, towering nearly 33 feet from the ground of the pit.
"Geologists have known about this for some time, and it even took us a while before we wrote it up," notes geologiest Marjorie Chan from the University of Utah. She and her colleague, Dennis I. Netoff, co-authored a paper describing the pit in detail.
“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."
"The pit-floor dune changes shape, height and position constantly, perhaps with every strong wind event," notes the paper. "At times, it completely covers the bedrock floor of the pit, whereas at other times bedrock is well-exposed." The researchers estimate that the sand can reach depths of 26 feet; though most of it is not coming from eroding walls – that powdery sand gets blown away – the dune’s sand is likely being blown in from elsewhere.
The researchers note that the pit also displays an intriguing array of wind-carved rock features. Of particular note are the dedos, sharp sets of finger-like projections in the sandstone. It is these features that bring to mind the iron-rich "blueberry" spherules seen on Mars by the Opportunity rover, 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, says Smithsonian.
"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," writes the researchers.
And for sure, the Cosmic Navel does have an otherworldly feel to it. While the top photo is a composite, which adds a bit to its surreality, there's no denying that a giant bowl in the desert filled with orange sand, complete with a jutting rock formation is a curious sight. We can thank Mother Nature and her cohorts, the wind and the water, for taking bellybutton gazing to a whole new level.