Subglacial and subaqueous processes near a glacier grounding line: sedimentological evidence from a former ice‐dammed lake, Achnasheen Scotland

Subglacial and subaqueous sediments deposited near the margin of a Late‐glacial ice‐dammed lake near Achnasheen, northern Scotland, are described and interpreted. The subglacial sediments consist of deformation tills and glacitectonites derived from pre‐existing glaciolacustrine deposits, and the subaqueous sediments consist of ice‐proximal outwash and sediment flow deposits, and distal turbidites. Sediment was delivered from the glacier to the lake by two main processes: (1) subglacial till deformation, which fed debris flows at the grounding line; and (2) meltwater transport, which fed sediment‐gravity flows on prograding outwash fans. Beyond the ice‐marginal environment, deposition was from turbidity currents, ice‐rafting and settling of suspended sediments. The exposures support the conclusion that the presence of a subglacial deforming layer can exert an important influence on sedimentation at the grounding lines of calving glaciers.