AbstractThe composition of rock glaciers was sounded by a combination of conventional geophysical methods near the lower limit of mountain permafrost in the Swiss Alps. P‐wave velocity, direct current (DC) resistivity and year‐round ground surface temperatures were measured on 32 talus‐derived rock glaciers. Subsurface P‐wave velocities differ significantly between non‐vegetated (probably active/inactive) rock glaciers and vegetated (probably relict) rock glaciers. DC resistivities reflect structural differences in the rock glaciers (e.g. bouldery or pebbly, ice‐cemented or highly ice‐rich) rather than thermal differences (i.e. frozen or unfrozen). The combination of these methods provides reliable thermal and structural information on subsurface deposits. In addition, mean annual ground surface temperatures are equally good indicators of the distribution of permafrost as bottom temperatures of snow. Copyright © 2006 John Wiley & Sons, Ltd.