Upheaval Dome: Utah's 'belly button' that has divided scientists since its discovery

Upheaval Dome is a rock formation in Utah with jagged peaks carved into concentric rings. Astronauts on board the International Space Station photographed the structure in 2007, sparking comparisons between the giant dome and a belly button.

Upheaval Dome stretches 3 miles (5 kilometers) across and 1,000 feet (300 meters) high. Its origin remains somewhat controversial, but the presence of shocked quartz crystals at the site suggests the dome mushroomed after a meteorite smashed into Earth 60 million years ago.

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Geologists think the meteorite impact initially left a bowl-shaped hollow in the ground, and that the edges of this hollow were unstable and eventually collapsed. Underlying rocks may then have risen to fill the void, creating the ridged structure we see today.

But not everyone agrees with this interpretation. Some scientists believe that Upheaval Dome was formed by a mountain of salt rising beneath southeastern Utah's sandstone layers.

A thick layer of salt originating from ancient landlocked seas sits beneath Canyonlands National Park. Salt is relatively light and can move around in rocks, much like ice can migrate at the bottom of a glacier, according to the National Park Service (NPS).

Salt is also less dense than sandstone, so it could have created a giant "bubble" that shoved the rocks aside as it surged upwards, according to the NPS.

Upheaval Dome is unlikely to be the salt bubble itself covered in sandstone, because erosion probably stripped several layers off the structure over the eons. Instead, the dome's center is considered to be a rocky base that formed beneath the salt bubble due to rocks falling into cracks around the edges of the bubble. These rocks may have rolled down along the sides of the bubble and piled up beneath the salt, creating the craggy feature we see today.

If true, the salt bubble theory would make Upheaval Dome the most deeply eroded salt structure in the world.

But the discovery of the shocked quartz crystals is the last published investigation into the origins of Upheaval Dome. It's unclear whether research is ongoing to settle the case once and for all.

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