Last month I told you about an unusual geographic feature of Toronto, the Leslie Street Spit. Today, I’d like to introduce you to another interesting local ecosystem.
The geography of the city is largely characterized by the network of ravines that crisscross the region and make up 17% of the city’s land area, as you can see by the map below:
Wikipedia provides the following account of how the ravines were formed:
The terrain that the city of Toronto sits on was formed after the end of the last ice age some 12,000 years ago. The glaciers flattened the terrain, and deposited a thick layer of loose sand and soil over the region. Over the millennia, small rivers and creeks eroded this soil cutting deep ravines through what is today the Toronto region. To the north of Toronto is the 1,900-square-kilometre (730 sq mi) Oak Ridges Moraine. The largest ravines are home to the rivers running south from the Moraine to Lake Ontario: the Humber River, the Don River, and the Rouge River. Smaller creeks and streams rise within Toronto from rain and melt water.
Apart from bridges that span them at points, the ravines have remained almost completely undeveloped, in large part because the areas are prone to flooding. Venturing into them is an often surreal experience. You step from the noise and bustle of the city and then, after descending downhill for a minute or so, suddenly find yourself in the middle of a forest.
The following images are from our walk last week through the Yellow Creek ravine which borders Rosedale, one of Toronto’s toniest neighbourhoods.
The ravines were heavily logged up to the mid-19th century, which is why the forest appears relatively young.
As you can see, even though the areas are largely left in their natural state, paths and trails are maintained and there have been measures taken to mitigate the effects of erosion on the banks of the streams.
