Utah’s Mount Timpanogos hides a glacier that is roughly 83% ice

A rubble-covered slope below Utah’s Mount Timpanogos contains much more ice than its rocky surface suggests. Gravity measurements indicate that the Timpanogos Rock Glacier is about 83 percent ice and 17 percent loose rock. The hidden body holds an estimated 1.5 million cubic meters of frozen water, roughly the volume of 600 Olympic swimming pools.

A Rock Glacier Looks Like Rubble From Above

Unlike a conventional glacier with exposed white ice, a rock glacier can resemble a broad pile of broken stone. Beneath that cover, ice fills much of the feature and moves slowly with the debris. Surface imagery can outline the landform, but it cannot show the depth, shape, or total ice hidden underneath.

The University of Utah team focused on one of the state’s largest examples, above Emerald Lake beneath Mount Timpanogos. The feature offered a test of whether small changes in gravitational pull could be turned into a three-dimensional picture of buried ice.

232 Gravity Readings Built the Hidden Map

During six field trips in fall 2024, researchers collected gravimeter readings at 232 points arranged across the rock glacier. Neighboring points were about 25 meters apart. Because dense mountain rock pulls slightly more strongly than lower-density ice, local decreases in measured gravity reveal where the buried ice is thicker.

The raw differences were tiny and required corrections for terrain, elevation, latitude, and the positions of the sun and moon. Researchers then used a Bayesian statistical method to reconstruct the internal structure in three dimensions. The calculation turned a grid of surface measurements into an estimate of the ice volume below.

The 83 Percent Estimate Reframes the Landform

The resulting picture suggests that the Timpanogos feature is overwhelmingly ice by volume. Its estimated frozen-water content is about 1.5 million cubic meters. A person crossing loose rock at the surface could be standing above ice tens of meters thick without seeing a conventional glacier.

The percentage is a model-based estimate, not a direct count of every block and void. Its strength comes from the large density contrast between rock and ice and the dense measurement grid. Additional geophysical methods or carefully placed drilling could test the reconstruction at selected points.

Falling Rock May Preserve Snow for Millennia

A companion study modeled how Utah rock glaciers form. In steep cirques, material eroding from the headwall repeatedly buries persistent snow. The debris protects snow from direct sun and warm air, allowing layers to accumulate and gradually form an ice-rich body under the rocky cover.

The model indicates that these features formed during the thousands of years after the major Ice Age glaciers disappeared rather than simply surviving unchanged from that earlier maximum. That origin makes continuing rockfall, snowfall, and climate conditions part of the glacier’s history.

Utah Has Hundreds of Similar Features

Satellite surveys have identified 836 rock glaciers across Utah, including examples in the Wasatch and Uinta ranges and the La Sal Mountains. The detailed Timpanogos measurements allowed researchers to relate surface area to buried ice volume, then use that relationship for broader estimates.

The extrapolation suggests Utah’s rock glaciers may collectively hold about one gigaton of water. Global estimates from roughly 50,000 known features reach about 48 gigatons. Those totals carry more uncertainty than the intensive Timpanogos map because every landform has different geometry and ice content.

Hidden Ice Is a Water Store, Not a Simple Reservoir

Frozen water in a rock glacier is not immediately available like water behind a dam. Release depends on melting, drainage paths, season, and the long-term stability of the feature. Faster thaw could add water temporarily while reducing the store that supports later flow.

The main advance is a way to measure an ice body that cannot be judged reliably from appearance. Repeating gravity surveys could test whether internal mass changes over time. For a warming mountain region, knowing where the ice is and how much exists is the first step toward understanding what its loss might mean.

The gravimeter method could be especially useful where drilling would be destructive, expensive, or too sparse to describe an entire landform. A borehole provides a direct answer at one point, while a gravity grid supplies continuous spatial coverage through a model. Using a few direct checks to calibrate a broad geophysical map could combine the strengths of both approaches.

Debris cover complicates climate response as well. Rock can insulate ice from summer warmth, but meltwater and air can still move through openings, and the cover itself shifts. Measurements of surface motion, internal temperature, and water discharge would show whether the Timpanogos body is stable, shrinking, or redistributing beneath the rubble. The 83 percent estimate provides a baseline for that monitoring.

The water comparison should not imply that the buried ice can be managed like 600 pools. It is distributed through a moving mixture of rock and ice high on a mountain. Its hydrologic importance depends on when meltwater exits and where it flows. Mapping that timing is the step that connects an impressive volume estimate to downstream water questions.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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