Active ice-sheet deglaciation and ice-dammed lakes in the northern Cairngorm Mountains, Scotland

Mapping of ice-marginal and glaciolacustrine deposits in the northern Cairn gorm Mountains allows the nature of deglaciation following the Last Glacial Maximum (c.18 000 BP) to be reinterpreted. Two ice-dammed lakes were ponde d between the Glenmore lobe of the Scottish ice sheet and local glaciers dr aining northwards from the Cairngorm Mountains. Delta progradation from the southern end of each lake reflects dominant meltwater sources and glacio-h ydrological gradients. Sediment facies representing subaqueous mass-flow de posits, lake-bottom rhythmites, lower and upper foresets and topsets are as sociated with prograding delta fronts. Moraines show that the lakes were ic e dammed at both ends, evidence that active glaciers existed in the Cairngo rm Mountains while ice was retreating from Strath Spey, and that deglaciati on was punctuated by readvances of the ice margin. These results indicate t hat an ice-stagnation model of deglaciation is invalid for most of the dura tion of ice wastage, but instead support an active-retreat hypothesis with multiple, climatically forced readvances.