The deglaciation of northern Gaspe Peninsula, Quebec: The location of Appalachian ice margins during the Older and Younger Dryas cold phases

The deglaciation of northern Gaspe Peninsula, Quebec: The location of Appal achian ice margins during the Older and Younger Dryas cold phases. Mapping and C-14 dating of quaternary deposits and landforms of deeply incised coas tal valleys, over a 100 km stretch between Cap-au-Renard and Petite-Vallee along the northern coastline of the Gaspe Peninsula, permit a detailed reco nstruction of Late Wisconsin deglaciation. During the glacial maximum these coastal valleys were occupied by glacier tongues which flowed out to the G ulf of St Lawrence from an ice-cap developed on the high and intermediate l evel plateaux in the interior of the Gaspe Peninsula. Initial deglaciation of the coast occurred towards 13 300 yrs BP, but massive ice contact marine deltas at or close to the mouths of four valleys between 12 300 and 11 800 yrs BP, are indicative of a long period of stability of glacier fronts in contact with the postglacial Goldthwait Sea. Meanwhile small catchment basi ns at the head of tributary gullies on the flanks of these valleys were occ upied by cirque glaciers, some of which remained active until at least 10 0 00 C-14 yrs BP. At Anse Pleureuse and Grande Vallee, a second generation of ice-contact marine deltas, indicates a later pause during ice retreat, bet ween 11 000 and 10 000 yrs BP. The two major pauses during ice front retrea t, indicated by such deposits coincide with the Older and the Younger Dryas cold phases. Correlations with late glacial readvances recognised elsewher e in the Laurentian axis between the Great Lakes and Newfoundland, and with amphi-Atlantic oscillations suggest that secular climatic change was respo nsible for both events.