Active and transitional rock glaciers above the 0°C mean annual air temperature isotherm in the La Sal Mountains, Utah, USA

Rock glaciers are common features in alpine environments that play an important role in hydrology and landscape evolution. We use satellite-based radar interferometry, topographic data, and optical imagery to identify and characterize rock glacier motion in the La Sal Mountains, Utah, USA, from 2016–2024. Our inventory includes 41 active and transitional rock glaciers and 20 relict features. Active and transitional rock glaciers occur at a mean elevation of 3266 ± 192 m, where mean annual air temperature (MAAT) is estimated at 1.99 ± 1.46°C for the 1991–2020 PRISM model climate normal. The mean downslope velocity is 6.8 ± 2.7 cm yr–1, with individual velocities ranging from 2.7 to 12.8 cm yr–1. Displacement time series from 20 representative rock glaciers reveal strong seasonal variability, with rates reaching up to 87.6 cm yr–1 in late summer when liquid water availability is greatest. Notably, these rock glaciers remain active or transitional despite being located above the 0°C MAAT isotherm for the 1991–2020 climate normal, suggesting a resilience to rising air temperatures. Our results provide insight into environmental controls on rock glacier kinematics and demonstrate an approach for developing inventories critical to improving estimates of alpine water storage.