LATE-GLACIAL (ALLEROD YOUNGER DRYAS) BURIED ORGANIC DEPOSITS, NOVA-SCOTIA, CANADA

Numerous deposits of organic, shallow-pond sediments and wetland peat accumulations buried by minerogenic sediments have been discovered thr oughout Nova Scotia. They are interpreted as representing a late-glaci al climatic oscillation correlative with the Allerod/Younger Dryas eve nt of Europe and the North Atlantic Ocean. The organic deposits began forming during the warm or warming interval following deglaciation and often record a transition to colder conditions. The climatic reversio n recorded in many deposits began about 10.8 ka BP and continued or su stained cooling culminated in the burial of the organic deposits by mi nerogenic sediments indicative of solifluction and mass-wasting proces ses. Some deposits provide strong evidence for regeneration, or rejuve nation of local glaciers. As the organic deposits are not as susceptib le as lake sediments to contamination by old carbon, they provide a mo re reliable chronological framework for deglaciation and late-glacial vegetational history. Palynological evidence shows that pioneer herb t undra communities colonized some areas shortly after 13 ka BP. Willow and birch shrubs followed soon after. Spruce woodlands had migrated in to the region prior to 10.8 ka BP but had not yet reached the northeas t mainland and Cape Breton Island. Cooling after 10.8 ka BP decimated tree populations and favoured a return to shrub and herb communities. The record in die buried deposits was then truncated by deposition of minerogenic sediments, and lake sediment sequences from deeper basins with continuous sedimentation are required to complete the record.