Late Wisconsin white spruce (Picea glauca (Moench) Voss) at Brampton, Ontario

Abstract

Study of late Wisconsin deposits in a small bog on the crest of Brampton esker (mantled by the Halton Till), about 30 km west of Toronto, Ontario, yielded a radiocarbon date of 12,320 .+-. 360 yr BP (BGS-551) for a sample of white spruce cones that contained fully-developed seeds. This data on cones (in gyttja) provides an estimate of minimum age for the lower boundary of the spruce pollen zone in southern Ontario. Silty clay beneath the gyttja yielded leaves of Dryas integrifolia and pollen assemblages (a herb pollen zone) that indicate presence of a dwarf-shrub tundra (essentially treeless) type of vegetation. This study supports the Port Huron Stadial age (about 13,000 yr BP) of the Halton Till that underlies the silty clay, and suggests an age of between 12,500-13,000 yr BP for glacial Lake Peel in the Brampton area that preceded the glacial Lake Iroquois phase in the Lake Ontario basin.