Beneath Utah’s rocky slopes, scientists mapped a buried glacier packed with enough ice to power a major hydroelectric dam for years and reveal a hidden freshwater reserve that could rewrite how the arid West counts its water

Walk across the rubble-covered slopes beneath Mount Timpanogos in Utah and you’d never guess what lies underfoot. What looks like a sprawling field of loose rock is, in fact, a buried glacier — and up to 120 feet of ice hides just beneath the surface debris, completely invisible from above.

University of Utah researchers have now mapped that hidden mass in three dimensions, finding it is 83% ice. The formation, known as a rock glacier, may be just one example of an overlooked freshwater reserve scattered across mountain ranges worldwide.

A glacier hiding in plain sight

Rock glaciers look nothing like the gleaming ice rivers most people picture. Instead of exposed ice, they resemble sprawling fields of broken rubble — the kind of terrain you might cross on a high-altitude hike without a second thought. That disguise is exactly what makes them so easy to overlook.

The Timpanogos Rock Glacier sits near the base of Mount Timpanogos — one of the Wasatch Range’s most prominent summits, close to both Salt Lake City and Provo.

These formations aren’t rare in Utah. They appear throughout the Wasatch and Uinta ranges and on the Colorado Plateau in the La Sal Mountains near Moab, with 836 identified rock glaciers mapped statewide through satellite imagery.

The Timpanogos Rock Glacier sits near the base of Mount Timpanogos — one of the Wasatch Range’s most prominent summits, close to both Salt Lake City and Provo. It’s one of the largest examples in the state. New research confirms it contains roughly 1.5 million cubic meters of frozen water, enough to fill about 600 Olympic swimming pools. Ice makes up 83% of the glacier’s total volume. The remaining 17% is loose rock.

How scientists ‘saw’ through the rock

Mapping something buried under debris requires tools that can sense what the eye can’t. The University of Utah team used a gravimeter — an instrument sensitive enough to detect tiny differences in gravitational pull caused by variations in material density. Ice is far less dense than rock, and that contrast is measurable.

Lead researcher Bronson Cvijanovich made six field trips to the glacier during fall 2024, hauling the gravimeter up to the formation above Emerald Lake and collecting measurements at 232 locations arranged in a 25-meter grid across the surface.

Raw gravity data is never clean. Researchers had to correct for the gravitational influence of the sun and moon, along with variations caused by terrain, latitude, and elevation — only then could they begin interpreting what lay beneath.

The team applied a new 3D Bayesian inversion method to reconstruct the glacier’s internal structure, essentially building a three-dimensional picture from corrected gravity readings. Geophysics professor Michael Thorne compared it to a CT scan: a way to reveal interior anatomy without cutting anything open. “We spent months of computation time doing the imaging with our new techniques,” Thorne said.

How these glaciers grow — and why they survived the Ice Age

The research also produced a new mathematical model describing how rock glaciers form and persist. The mechanism centers on repeated rockfalls: as debris tumbles down steep mountain walls, it buries patches of persistent snow, insulating them from the sun and allowing ice to accumulate over thousands of years.

In the Wasatch Mountains, the mountains themselves drive this process. “The mountains themselves are eroding and burying the snow, and that’s why the rock glaciers exist,” said glaciology professor Leif Anderson. The erosion isn’t incidental — it’s the engine.

One counterintuitive finding emerged from the data. Utah’s rock glaciers aren’t Ice Age relics. The last glacial maximum peaked roughly 18,000 to 21,000 years ago, and the large ice sheets that defined that period have long since retreated. Utah’s rock glaciers developed after those major glaciers disappeared — younger features, built up gradually in the millennia since.

A global freshwater reserve hiding under rubble

Scaling up from a single glacier to a global picture requires extrapolation, and the researchers were careful about how they did it. Using detailed measurements from Timpanogos, they established a relationship between a rock glacier’s surface area — visible from satellite — and the volume of ice likely stored beneath.

Applied to roughly 50,000 known rock glaciers worldwide, that relationship yields a collective estimate of about 48 gigatons of water. One gigaton equals one billion metric tons, or enough water to fill 400,000 Olympic swimming pools.

Utah alone may hold around 1 gigaton — approximately 815,000 acre-feet of water, a substantial share of the state’s total freshwater picture, much of it previously uncounted.

Why this matters for water security

The American West is already dealing with water scarcity. Reservoirs run low, rivers are over-allocated, and climate projections suggest conditions will tighten further. Identifying a large category of freshwater that hasn’t been fully accounted for carries real practical weight.

Satellite imagery can outline a rock glacier’s footprint, but depth and ice volume remain invisible from above. That’s precisely the gap the gravity-based method addresses. Without knowing how much ice sits beneath the surface, water managers can’t include rock glaciers in their calculations at all.

The implication extends well beyond Utah. Similar unmapped reserves likely exist beneath rocky slopes across South America, Central Asia, and other mountain regions — waiting for the same kind of scrutiny.

Both studies are peer-reviewed. The gravity imaging research appeared August 26 in the Journal of Geophysical Research, while the formation model was published earlier in Geophysical Research Letters. Together, they offer a template for systematically surveying rock glaciers elsewhere and filling in one of hydrology’s most significant blind spots.

Daniel Garcia

Daniel García is an Editor-in-Chief with strong expertise in structural work and engineering principles. He combines this technical foundation with deep knowledge of energy, spatial design, and emerging technologies, bringing a forward-thinking and analytical approach to editorial leadership.