Mass Addition to Timpanogos Rock Glacier: Debris‐Covered Snow and the Importance of Interannual Variability in Headwall Erosion and Climate

Abstract The processes of ice incorporation into rock glaciers have been difficult to quantify in both permafrost and non‐permafrost conditions. Here, we develop a numerical model that regardless of the presence of permafrost, reveals how debris eroded from hillslopes and deposited on snow can add ice mass to rock glaciers in pulses. Importantly, we honor the reality in all mountain systems that snow amount, snow avalanches, melt, and mass wasting vary stochastically. Our probabilistic model reproduces the internal stratigraphy (of firn and debris) from high on Timpanogos Rock Glacier, Wasatch Mountains, Utah, USA, which intermittently has an accumulation zone. Even in the modern arid, warming western United States the combined variability of familiar mountain processes allows rock glaciers to add ice. We provide a numerical framework for simulating the continuum between glaciers, debris‐covered glaciers, and rock glaciers in response to climate change.