Hidden Ice Under Utah's Rock Piles May Total a Billion Tons, Studies Find

Rock glaciers—piles of rock that hide large, unaccounted-for masses of ice—are common across Utah's Wasatch and Uinta ranges and even appear in the La Sal Mountains on the Colorado Plateau near Moab. University of Utah geologists have now brought one of the state's largest, the Timpanogos Rock Glacier beneath Mount Timpanogos near Salt Lake City and Provo, into sharp focus in two new studies documenting how it formed and how much ice it holds.

The researchers found Timpanogos Rock Glacier stores enough frozen water to fill 600 Olympic swimming pools, or 1.5 million cubic meters (about 396 million gallons)—equivalent to the volume of the largest pyramid at Giza in Egypt. “Timpanogos Rock Glacier is surprisingly ice-rich. It is 83% ice and 17% loose rock,” said Bronson Cvijanovich, lead author of one of the studies. “There's a lot of ice that's hidden in Utah's mountains,” said glaciology professor Leif Anderson, noting that walkers can be standing over 120 feet (37 meters) of buried ice without knowing it.

To find it, Cvijanovich carried a sensitive gravimeter to the glacier above Emerald Lake in fall 2024, taking gravity readings at 232 locations spaced 25 meters apart across six field trips. Because rock and ice have different densities, larger drops in gravitational pull revealed thicker ice underneath. After correcting for the sun, moon, terrain, latitude and elevation, the team spent months developing a new 3D imaging method using Bayesian statistics.

A second study found Utah's rock glaciers are not remnants of the Ice Age, which peaked 21,000 to 18,000 years ago, but water stores that formed over the thousands of years since those glaciers melted, as rockfalls buried persistent snow in the upper parts of the rock glaciers, according to a new mathematical model the researchers developed.

Timpanogos is one of 836 rock glaciers documented in Utah using satellite imagery. Using the relationship they found between a rock glacier's surface area and its ice volume, the researchers estimate the world's 50,000 known rock glaciers hold 48 gigatons of water altogether—a gigaton being 1 billion metric tons, equal to a cubic kilometer, or enough to fill 400,000 Olympic pools. Utah's own rock glaciers, they estimate, hold about 1 gigaton, or 815,000 acre-feet (about 266 billion gallons), of water.