Genetic variability of rock glaciers

Rock glaciers, common in many alpine and polar regions,have poorly understo od internal structure,dynamics, and origins. A renewal of interest in the c limatic and geomorphic significance of these striking landforms has served to intensify a long-standing controversy surrounding the genesis of rock gl aciers. The controversy, which began more than 30 rears ago, has resolved i nto two primary viewpoints. One holds that rock glaciers form through a con tinuum of glacial to periglacial processes and encompass features that vary from debris-covered glaciers to slightly remobilized talus or till. The op posing view holds that all rock glaciers are exclusively features of creepi ng permafrost, genetically distinct from glaciers. Several factors have pro longed this debate: (1) sparse direct observations of internal composition and processes of ice formation; (2) few long-term measurements of rock glac ier deformation; (3) difficulties in establishing geophysical, geochemical, or petrographic methods that unequivocally distinguish between ice of glac ial and periglacial origins; (4) difficult access and remote locations of m ost rock glaciers; and (5) often arbitrary terminological distinctions betw een "glacial" and "periglacial" processes. Results from several recent stud ies, some presented in this volume, demonstrate conclusively that at least some rock glaciers are glacigenic, making untenable the view of rock glacie rs as exclusively periglacial. This conclusion indicates that several previ ously held concepts of rock glacier dynamics and development should be re-e valuated. In addition, it highlights the need for researchers to move beyon d taxonomic arguments, and to improve understanding of fundamental aspects of rock glaciers such as climatic sensitivity, geochemistry, hydrology, dyn amics, structure, mass balance, and genetic and spatial variability.