Lake Ontario is the last in the chain of Great Lakes along the Canada-Unites
States border, which together contain one fifth of the world's fresh
water. It was formed by the same glacial processes that formed all
of the other Great Lakes. Between one million and 14 000 years ago,
ice sheets were advancing and retreating in cycles across this part
of North America. These ice sheets were large and often over two
kilometres thick. They extended as far south as Wisconsin and northern
New York State so that this period is often called the Wisconsin
During periods when the glaciers were growing and advancing southward,
they scraped the land below them and pushed the accumulated piles
of debris such as rocks, sand, silt and clay along in front of them
as they moved. This scraping is called 'glacial scour', and it has
resulted in the deepening of river valleys, the flattening of bedrock
and the levelling of hills. When the glaciers melted and retreated,
they left behind the piles of material that they scraped up and
pushed along. This resulted in the formation of raised ridges called
moraines. They also left water behind as they melted. This meltwater
flowed into the scraped out areas the glaciers had created, forming
the precursors of the Great Lakes about 14 000 years ago.
The presence of these large lakes moderates the local climate; summers
are cooler and winters are warmer than they would be without a large
body of water nearby. This effect adds to the already warm temperatures
typical of southern Ontario because of its lower latitude. The lakes
also increase the amount of local precipitation in the area, particularly
on the downwind side of the lakes.
fruit at Centre Mall's Farmers' Market in Hamilton. Photo
by Betty Blashill.
are some of the factors contributing to why crops can be grown here
that otherwise would be impossible to grow. Wine grapes and other
soft fruit such as peaches can be grown in very few places in Canada
and the Hamilton region is one of them.