Utah’s mountains may be hiding a surprisingly large supply of frozen water beneath piles of loose rock.
New research suggests the state’s hundreds of rock glaciers could collectively contain around 1 billion metric tons of water.
Unlike conventional glaciers, rock glaciers do not necessarily look like giant masses of ice. Their surfaces are covered by rocks and debris, hiding large quantities of frozen material underneath.
They are common in Utah’s Wasatch and Uinta mountain ranges and can also be found in the La Sal Mountains near Moab.
Researchers at the University of Utah have now taken a detailed look inside one of the state’s largest examples, Timpanogos Rock Glacier, located beneath Mount Timpanogos near Salt Lake City and Provo.
Two new studies examined how the rock glacier formed and estimated how much ice it contains. The scientists developed a technique that uses tiny differences in gravity to create a three-dimensional picture of the ice hidden beneath the rocks.
Their results revealed an unexpectedly ice-rich structure. Timpanogos Rock Glacier is estimated to consist of about 83% ice and 17% loose rock.
The glacier contains around 1.5 million cubic meters, or approximately 396 million gallons, of frozen water. That is enough to fill about 600 Olympic-sized swimming pools.
In some places, people walking across what appears to be ordinary mountain rubble could have around 37 meters, or 120 feet, of ice beneath their feet.
To map this hidden ice, former University of Utah graduate student Bronson Cvijanovich and his colleagues carried sensitive equipment onto the rock glacier during six field trips in 2024. They collected gravity measurements at 232 locations across its surface.
The technique works because rock is much denser than ice. Areas containing thicker ice produce a slightly weaker gravitational pull than areas dominated by rock.
However, interpreting these extremely small differences is complicated. The researchers had to correct their measurements for factors including elevation, latitude, surrounding terrain and even gravitational effects from the sun and moon.
They then used advanced statistical methods to reconstruct the buried ice in three dimensions, a process that required months of computer calculations.
The research also provides clues about how Utah’s rock glaciers formed. Rather than simply being leftover ice from the last Ice Age, the researchers believe many developed during the thousands of years that followed.
In steep mountain valleys, falling rocks can bury patches of snow that survive through the warmer months. Once covered by debris, the snow is protected from sunlight and heat. Over long periods, repeated rockfalls and snowfall can gradually create thick bodies of buried ice.
Scientists have identified 836 rock glaciers across Utah using satellite images. Based on the detailed measurements at Timpanogos, the researchers developed a relationship between a rock glacier’s visible surface area and the amount of ice it may contain.
Using this approach, they estimate Utah’s rock glaciers could collectively store about 1 gigaton of water, equivalent to roughly 266 billion gallons.
The researchers also applied their calculations more broadly. Around 50,000 rock glaciers are known worldwide, and together they may hold approximately 48 gigatons of water.
The findings reveal that mountain landscapes that appear to be nothing more than piles of rock may actually contain enormous and previously overlooked stores of frozen freshwater.
