CHARACTERIZING ROCK GLACIERS USING REMOTE SENSING AND THE IMPLICATIONS FOR WATER RESOURCES: EXAMPLE FROM MT. MESTAS, SOUTHERN COLORADO

A rock glacier is a rocky mass that, at some point, contained interstitial ice. They are critical water resources for alpine ecosystems. Their importance as a resource is directly related to the amount of interstitial ice within the rock glacier, and they can be classified into three groups: active, inactive, and fossil. Active rock glaciers contain sufficient interstitial ice to allow the landform to flow plastically, with the ice at the pressure-melting point; they are sources of water year-round. Inactive rock glaciers still contain ice, but not enough to allow for flow. Fossil rock glaciers no longer contain any ice. For the purposes of this study, the rock glaciers on Mt. Mestas, Colorado were studied. Mt. Mestas has 44 rock glaciers between 2800 and 3000 m in elevation (below the elevation of glaciation) which are composed of clasts exfoliated from the felsic laccolith. Two different methods of remote sensing are used to characterize these rock glaciers based on their ice content. Interferometric Synthetic Aperture Radar (InSAR) is used to measure the flow rate of rock glaciers. If a rock glacier has observable flow, it is, by definition, active, and contains ice. Flow was observed on several rock glaciers on Mt. Mestas with flow rates ranging from 5 to 40 mm/yr. The presence of ground ice likely influences the heat flow and thermal character of the rock glacier. Thermal infrared data from Landsat 7 and 8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are used to calculate the apparent thermal inertia of different classes of rock glacier activity (active vs. inactive or fossil). Preliminary analysis shows differences between the apparent thermal inertia in rock glaciers with measured movement and those without. We can apply these methods to classify rock glaciers by the amount of ice inside and the compare the results to known water resources on Mt. Mestas.