Lago Puyehue is a glacigenic lake in the Chilean Lake District (40 degrees S) with a complex deglaciation history. A detailed seismic-stratigraphic study of its sedimentary infill indicates a much earlier retreat of the glacier from the Lago Puyehue basin than the neighbouring glacier from the Lago Rupanco basin. Because of their close proximity, Rupanco meltwater streams played an important part in the depositional processes of Lago Puyehue. A timing discrepancy between the in-lake ages of a sediment core and the outer-lake ages of moraine deposits (re) opens the discussion on the timing of deglaciation in the Southern Hemisphere. Copyright (C) 2011 John Wiley & Sons, Ltd.