DELAYED DEGLACIATION BY DOWNWASTING OF THE NORTHEAST AVALON PENINSULA, NEWFOUNDLAND - AN APPLICATION OF THE EARLY POSTGLACIAL POLLEN RECORD

Basal radiocarbon dates from lake sites indicate that final deglaciati on began at most a few centuries before 10 ka BP on the interior plate au and proceeded by down-wasting. Comparison of the pollen record with the sequence of vegetation from the Storbreen glacier foreland, Norwa y, studied by the Jotunheimen Research Expeditions, indicates that pio neer herb and dwarf shrub stages gave way within 200 years to shrub-bi rch heath into which spruce migrated at about 8.5 ka BP. it is shown t hat double maxima of dwarf shrubs result from the existence of terrain s of different ages within each catchment at the time when lake sedime nt accumulation began. An independently dated pollen record from St. J ohn's Harbour confirms the timing and mode of deglaciation and demonst rates that the Avalon Peninsula ice cap did not extend beyond the pres ent coast at the beginning of the Holocene. The delays in both deglaci ation and the immigration of spruce are attributed to cold ocean tempe ratures associated with eastward discharge of meltwater from the Laure ntide Ice Sheet.