Upheaval Dome
Key facts
- Country
- United States
- Diameter
- 5.5 km
- Age
- probably less than 170 million years
- Location
- 38.44° N, 109.93° W
A spectacular eroded bowl in Canyonlands National Park, Utah, about 5 km across, with a jumbled central core of pale and greenish rock ringed by cliffs of red sandstone.
Upheaval Dome, in Canyonlands National Park in Utah, is one of the most spectacular and debated structures in the American West. From the overlook, visitors see a vast bowl of eroded rock, with a jumbled central core of white, grey and greenish layers surrounded by rings of red sandstone cliffs. For decades geologists argued about how it formed.
Two ideas. Upheaval Dome is a round structure about 5 km across, where layers of rock that are normally flat have been pushed up into a dome and then deeply eroded. There were two main explanations. One was that it was a salt dome, formed when a layer of salt deep underground, which is lighter than the rocks above, slowly rose upwards like a bubble, pushing the overlying rocks into a dome. Salt structures are common in this part of Utah. The other idea was that it was the deeply eroded remains of an impact crater, with the dome being the central uplift.
The evidence. In 2008 geologists reported finding shocked quartz in rocks from Upheaval Dome. Shocked quartz contains microscopic features that form only under the extreme pressures of a shock wave, and it cannot be produced by a rising salt dome. This discovery provided strong evidence for an impact, and Upheaval Dome is now widely accepted as an impact structure. Some geologists still discuss the details, but most now agree on an impact origin.
Age and size. The impact must have happened after the youngest rock layers that were deformed by it were deposited, which suggests it is less than about 170 million years old. Its exact age is unknown. Erosion has removed perhaps a kilometre or more of rock from above the structure, so the crater we would have seen at the time of the impact was larger than the 5 km structure visible today, perhaps around 10 km.
A window into a crater. Because erosion has cut so deeply, Upheaval Dome lets geologists see deep into the structure of an impact crater, including how rock layers were folded and faulted beneath the crater floor. This makes it a useful comparison for eroded craters on Mars, where similar features are seen.
Visiting. Upheaval Dome is in the Island in the Sky district of Canyonlands National Park. A short trail leads from the car park to two overlooks with views into the structure. Longer, more demanding trails lead into the dome itself. The desert can be extremely hot in summer, so carry plenty of water. Collecting rocks in national parks is illegal.
Why it matters. Upheaval Dome shows how scientific debates are resolved by finding the right evidence, and it is one of the most visually striking impact structures in North America.
Did you know?
Upheaval Dome was long thought by many to be a salt dome.
Shocked quartz reported in 2008 provided strong evidence for an impact.
Erosion has cut deep into the structure, exposing rocks that once lay far beneath the crater floor.