MAPPING THE INTERNAL ICE OF TIMPANOGOS ROCK GLACIER, UTAH USING GRAVIMETRY AND 3-D BAYESIAN INVERSION

Despite their abundance and persistence in mountain environments, rock glaciers receive little attention compared to glaciers. Although smaller in volume, rock glaciers are more resilient to rising temperatures due to their insulating debris cover and they can provide vital baseflow late in the melt season in addition to acting as refugia for cold-loving species. Developing methods to measure their ice content is increasingly relevant as climate change progresses and glaciers retreat into cirques. In this study, we quantify the ice thickness across Timpanogos Rock Glacier, which persists within 6 km of the urban Wasatch Front. In Fall 2024, we collected 232 relative gravity measurements using a Scintrex CG-6 gravimeter on and around the rock glacier. Positions and elevations were measured with a real time kinematic (RTK) GNSS receiver. After applying standard gravity corrections, we obtain complete Bouguer anomalies with a maximum of roughly -1.8 mGal at the upper end of the glacier, suggesting maximum ice thickness on the order of tens of meters. We invert these gravity data using both 2-D and 3-D Bayesian inversion schemes. To the best of our knowledge, this is the largest rock glacier ever imaged in 3D. Our early findings show that even in arid regions devoid of glaciers like Utah, rock glaciers can contain significant amounts of ice that appear to be sustained in the modern climate.