The geochemical record in rock glaciers

A 9.5 m ice core was extracted from beneath the surficial debris cover of a rock glacier at Galena Creek, northwestern Wyoming. The core contains clea n, bubble-rich ice with silty debris lavers spaced at roughly 20 cm interva ls. The debris layers are similar in appearance to those in typical alpine glaciers, reflecting concentration of debris by melting at the surface duri ng the summer ablation season. Profiles of stable isotope concentrations an d electrical conductivity measurements provide independent evidence for mel ting in association with debris layers. These observations are consistent w ith a glacial origin for the ice, substantiating the glacigenic model for r ock glacier formation. The deuterium excess profile in the ice indicates th at the total depth of meltwater infiltration is less than the thickness of one annual layer, suggesting that isotope values and other geochemical sign atures are preserved at annual resolution. This finding demonstrates the po tential for obtaining useful paleoclimate information from rock glacier ice .