An early stage in formation of a composite debris cone in the glacial trough of the Lochan na Lairige, on Ben Lawers, is 14C dated to 6398–6225 cal BP. A large proportion of the fan comprises a structureless gravel with boulders, possibly deposited in a single event. Blanket peat formed on the fan surface at 3820–3496 cal BP. Sediment slurries are recorded across the peat after this time, at c. 3950 to c. 3100 cal BP, c. 2000 and c. 1400 cal BP, and at c. 1200 to c. 1100 cal BP. They were much less significant events. They can be related to periods of higher effective precipitation in the region.