SUBGLACIAL MELTWATER EROSION AT LOCH-TREIG

Reports of small scale features of glacial erosion by meltwater are ra re in Scotland. During the spring of 1996 unusually low water levels i n the Loch Treig reservoir revealed an assemblage of exceptionally wel l-preserved glacial erosion forms sculpted in bedrock, including a sui te of meltwater erosion forms. Within the assemblage of landforms at L och Treig, there is a predominance of forms created by the now of subg lacial meltwater and limited evidence of glacial abrasion. The Loch Tr eig features are therefore classed as subglacial meltwater erosion for ms (s-forms and not p-forms). As such they are probably unique in Scot land. The meltwater forms described from this site include scallops, c hutes, chute pools, potholes, and the less specific 'undulose smoothin g' of bedrock surfaces. Large groups of 1-1.5 m-diameter scallops are interpreted as phreatic (formed below the water table) in origin. The potholes range from 0.5 m to over 3 m in diameter, with the larger pot holes usually occurring in a series with interconnecting chutes. Chute s, chute pools and potholes are interpreted as vadose (formed above th e water table) in origin. This interpretation of the suite of features accords well with the established Loch Lomond Stadial events in the a rea, which suggests that a substantial active glacier was still presen t in the north end of Glen Treig after the drainage of an ice dammed l ake at 260 m in the Spean-Laggan area.