Rock glaciers and permafrost in Trollaskagi, northern Iceland

This paper examines the distribution of rock glaciers within a field area situated close to the village of Holar in central Trollaskagi, northern Iceland, at 65 degrees 44'N 19 degrees 05'W Our investigations show that rock glaciers develop at the foot of steep, northerly exposed rock faces where snow accumulates from snow avalanches and snow-drifting associated with prevailing southerly winter winds. Most rock glaciers seem to be glacier derived, but talus-derived features with ground ice occur as well. Estimated rockwall retreat rates at rock glacier sites reveal minimum values of 0.4-1.2 mm a(-1) Such high rates are probably to a large extent governed by frost shattering through prolonged contact with snow and ice at the lower parts of the rockwalls. Temperature measurements indicate extensive permafrost occurrences within the field area and that these rock glaciers are true permafrost features.