Hidden Beneath Utah's Rubble Lies a Glacier the Size of the Great Pyramid

A Mountain's Surprising Secret

To anyone hiking the trails of Mount Timpanogos in Utah's Wasatch Range, the sprawling field of loose rock near the summit looks like nothing more than a giant pile of debris. But scientists have now confirmed what lay hidden beneath those stones all along: an enormous reservoir of ice, quietly storing enough frozen water to fill 600 Olympic swimming pools.

University of Utah scientists mapped 1.55 million cubic meters of hidden ice beneath the Timpanogos Rock Glacier using gravity measurements. The volume is equivalent to that of the largest pyramid at Giza in Egypt, according to lead researcher Bronson Cvijanovich. It's a staggering find hiding in plain sight — one that could reshape how scientists think about freshwater reserves across the American West.

How Scientists Cracked the Code

To estimate the ice content, a team hiked about five miles with an elevation gain of 3,500 feet to reach the rock glacier on different occasions in 2024, hauling sensitive instruments like a gravimeter, and took gravity readings at 232 spots separated by about 80 feet in a grid atop the rock glacier. It was painstaking, physically demanding work — six separate trips up a punishing trail, each time carrying precision equipment to one of the more remote corners of the Wasatch Range.

By measuring minute differences in gravitational pull between rock and ice, the team created a novel technique to image the 3D ice body within a large rock glacier. After those measurements were collected, the team had to correct them to account for differences in gravity due to factors like the position of the sun and the moon, the location's terrain, latitude, and elevation. The result was an unprecedented three-dimensional portrait of a hidden glacier — built not from drilling or digging, but from the subtle tug of gravity itself.

The researchers' modelling found an ice volume of 1.55 million cubic meters, with an average thickness of 18.8 meters. Their two-layer model estimated that the entire rock glacier contains 72% ice and 28% debris by volume, while the buried ice-rich core itself is 83% ice and 17% debris.

Not a Relic — A Living Water Store

Rock glaciers look very different from conventional glaciers. Instead of exposed ice, they resemble sprawling fields of loose rock, while potentially concealing large quantities of ice below the surface. That rocky armor is actually what keeps them alive. The surface layer of rock shields the frozen core from direct solar radiation and ambient heat. While some rock glaciers have already lost their ice cores, active formations like Timpanogos continue to store vital reserves right beneath the boots of unsuspecting hikers.

A second study found that Utah's rock glaciers are not left over from the Ice Age, but are instead water stores that formed thousands of years after Ice Age glaciers melted away. Their findings suggest rock glaciers form as falling debris buries persistent snow and preserves it for thousands of years. That distinction matters enormously — it means these formations are dynamic, ongoing systems, not frozen relics slowly winding down.

A Global Implication Hidden Under Rock

Rock glaciers are common in the Wasatch and Uinta ranges, and Timpanogos is one of 836 in the state of Utah alone. Utah's rock glaciers may hold as much as 1 gigaton, or 815,000 acre-feet of water, the researchers estimated. That's a meaningful water reserve for a region that regularly battles drought and increasing pressure on traditional water sources.

Using a new relationship derived from their findings, researchers estimate that the world's 50,000 known rock glaciers hold 48 gigatons of water — equal to 1 billion metric tons, or enough to fill 400,000 Olympic swimming pools. As traditional glaciers retreat under warming temperatures, these rocky, disguised formations may prove to be one of the most underappreciated freshwater reserves on the planet — and scientists are only just beginning to measure what's really inside them.