Algonquin is classic "Canadian Shield" country - some of the oldest rocks
on the North American content. The Algonquin highlands are a huge block of
1.5 billion year old rock. The Canadian Shield comes to the surface in a huge
circle around Hudson Bay. However, the Shield rocks extend west to the Rockies,
south-east to the Appalachians and as far south as Texas; however, they have been
buried under deposited sediment around the Great Lakes
and in the Great Plains area.
About half a billion years ago, a meteor slammed into the north end of the
park. It made a hole 4 kilometers (2.5 miles) wide and 600m (2000 feet) deep,
which is now called the Brent Crater. The road which goes in to this area
travels along a glacial "esker", a sand and gravel ridge probably left behind
by a river of meltwater flowing under a glacier, for the first 18 km (10 miles)
or so; after that, it gets somewhat bumpy.
About 11 thousand years ago, the last of the glaciers
scraped through the area now occupied by the park. Arctic plants still
remain in the Barron Canyon area in the northeastern part of the park.
The Barron Canyon itself was formed by the massive outpouring of glacial
meltwater from ancient Lake Algonquin.
Because the rock underlying the park doesn't drain very well, the park is
dotted with rivers, lakes and spruce bogs which are
often located in depressions gouged out by glaciers. With few exceptions,
the lakes tend to be acidic because there are very few soluble rocks such
as limestone within the park to balance acids
from plant material or acid rain.
In general, rivers and streams in the Canadian Shield do not tend
to carry much sediment since these ancient rocks are very resistent to
East Versus West
The eastern third of Algonquin is lower than the western two-thirds: there
is enough difference that
more precipitation falls on the western part of the park.
the western part is cooler than the eastern part.
some trees, such as the sugar maple, are much more common in the west;
similarly, the three varieties of pines - white, red and jack pine - are
more common in the east.
Virgin Forest - Hardly!
Most of the old-growth forest is gone from this area as a result of the area
being opened up for logging in the 1800's. Even today, there is a controversial
balance between wilderness, recreational use and managed forest.