Abstract:
This investigation comprises three parts: (1) the
source, mechanism of transport, and distribution of pollen,
spores and other palynomorphs in Georgian Bay bottom
sediments and a comparison of these data with the contemporary
vegetation, (2) the relative significance of fluvial
transportation of pollen and spores, and (3) the late- and
postglacial history of vegetational and climatic changes
in the Georgicin Bay region.
Modem pollen and spore assemblages in Georgian Bay do
reflect the surrovinding vegetation when preservation and
pollen production by the different species are considered
and accounted for. Relative pollen percentage and concentration
isopoll patterns indicate that rivers contribute
large quantities of pollen and spores to Georgian Bay. This
is further substantiated by large amounts of pollen and
spores which were caught in traps in the Moon, Muskoka, and
Nottawasaga Rivers which flow into Georgian Bay. The majority
of pollen and spores caught in these traps were washed into
the rivers by surface water runoff and so reflect the
vegetation of the watershed in a regional sense.
In a 12.9 metre long sediment core from northeastern
Georgian Bay the relative percentage and absolute pollen
concentrations allow correlation of Georgian Bay Lake phases with climatic and forest history. Four distinct pollen
zones are distinguished: zone GB IV which is the oldest,
reflects the succession from open spruce woodland to boreal
forest; zone GB III represents a period of pine-mixed hardwoods
forests from about 10,000 to 7,500 years ago. A pine-maplehemlock
association dominated in zone GB II, although during
the culmination of postglacial warming about 4,000 to 5,000
years ago the Georgian Bay forests had a more deciduous
character. Zone GB I clearly shows European man's
disturbance of the forest by logging activities.
