Hidden 'Rock Glacier' Under Utah Mountain Holds Enough Ice to Fill 600 Olympic Pools

A mountain of loose rock beneath Utah's Mount Timpanogos hides enough ice to fill 600 Olympic swimming pools, according to two new University of Utah studies. Unlike conventional glaciers, which expose broad expanses of ice, "rock glaciers" resemble slowly shifting fields of broken stone whose rocky covering conceals a thick body of ice, insulated from direct sunlight and warm air. Such formations are widespread in Utah's Wasatch and Uinta ranges and also appear on the Colorado Plateau near Moab.

The researchers found the Timpanogos Rock Glacier is 83% ice and 17% loose rock, holding about 1.5 million cubic meters of water — comparable in volume to the largest pyramid at Giza. "There's a lot of ice that's hidden in Utah's mountains," said glaciology professor Leif Anderson. "When we are high in the mountains and walking across loose rocks or rubble, you don't realize there could be 120 feet of ice buried beneath your feet."

Because the ice lies beneath rubble that satellite images cannot see through, lead author Bronson Cvijanovich led six expeditions in the fall of 2024, taking gravimeter readings at 232 points spaced 25 meters apart. The technique works because ice is far less dense than rock: thicker ice causes a slightly weaker gravitational pull, letting scientists reconstruct the buried ice's shape without drilling. Geophysics professor Michael Thorne said the team used Bayesian statistics and months of computation to build a three-dimensional picture of the ice, similar to how a CT scan uses radiation to reveal what's inside a body.

A second study found that Utah's rock glaciers are not direct remnants of the last Ice Age, which peaked 21,000 to 18,000 years ago. Instead, they formed over the thousands of years after the region's ancient glaciers disappeared, making them younger frozen reservoirs rather than leftover pieces of old ice sheets.

Satellite surveys have identified 836 rock glaciers in Utah alone. Applying the relationship between surface area and ice volume measured at Timpanogos to the roughly 50,000 known rock glaciers worldwide, the researchers calculated that they collectively store about 48 gigatons of water.