ROCK GLACIERS AND PERIGLACIAL ROCK-ICE FEATURES IN THE EASTERN SIERRA NEVADA; UPDATES ON CLASSIFICATION, MAPPING, CLIMATE RELATIONS, AND MONITORING

• Main Authors: Constance Millar, David Clow, Jessica Lundquist, Robert Westfall
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Ice; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.165.2570; http://www.fs.fed.us/psw/publications/millar/posters/millar_etal_poster_paclim2006.pdf

Rock glaciers and related periglacial rock-ice (R-I) features are common but little-studied landforms in high mountains where conditions are relatively dry and adequate sources of shattered rock exist. While many of these features in temperate mountains appear to be Pleistocene relicts, a large proportion shows indications of activity, suggesting persistent embedded or underlying ice. Recent retreat of “clean glaciers ” worldwide has been related to global warming. Rock-mantling and rock matrices, however, insulate rock glaciers and R-I features, and their activity and equilibrium with climate appear to considerably lag clean glaciers. They remain potentially important mountain reservoirs, yet overlooked in hydrologic research. For this and other reasons, research attention to the distribution, activity, genesis, and hydrology of rock glaciers has increased in recent years. Debate on the glaciogenic vs. periglacial (permafrost) origins of these features (Clark et al. 1998) has been confounded by inconsistent terms and definitions, lack of a sufficient classification, and by the varying expression of processes that occur under climatic and environmental conditions in different regions. Rock glaciers and R-I features are abundant in cirques and canyons of the Sierra Nevada south of Lake Tahoe, especially along the eastern escarpment, where they occur in diverse forms (Figs. 1 & 2). Several large valley rock glaciers have been studied for their climatic and neo-glacial relationships (Clark, pers. comm.; Konrad & Clark 1998), and a few Pleistocene relict rock glaciers are indicated on high-resolution geologic maps of the Sierra. These features are mentioned in passing in Sierran scientific and popular natural-history literature, but aside from Clark and his students ’ research, no systematic studies have been published. While several papers from Europe and North America describe types of rock glaciers, define terms, and offer classifications, none proved