Characteristics and evolution of two relict talus slopes in Scotland

Abstract

Vegetation‐covered relict talus slopes are widespread at the base of glacially steepened rockwalls in Scotland. Investigations carried out on two such slopes, one in the An Teallach massif in Wester Ross, the other on the flanks of West Lomond, Fife, suggest that these slopes accumulated as a result of rockfall in the interval between the retreat of the Late Devensian ice sheet and the end of the Loch Lomond Stadial. Other processes (basal erosion, avalanches and debris flow) were apparently not effective in modifying these slopes during accumulation. During the Holocene, however, rockfall accumulation at these sites has been almost negligible. Present‐day rockwall retreat rates average 0.015mm y^‐1 (excluding infrequent large‐scale falls) and are thus low in comparison with rates measured in other environments or calculated for the Loch Lomond Stadial. The main processes operating during the Holocene on these slopes are slope failure, debris flow, gullying and soil creep.