Hands up everybody who knows that Casa Loma sits on the shore of an ancient lake formed by glacial meltwater.
Nick Eyles’ book will clue you in to the geology of Toronto and the surrounding region. It comes complete with maps, cross-sectional diagrams, and a history of the Toronto area in stones. The author describes everything from the ancient formation of North America from smaller sub-continental plates to the recent sediments that form the Don Valley Brickworks.
Here are a few of the things I learned:
* The fossil corals I saw in my childhood are from a Devonian coral reef in Port Colborne on Lake Erie.
* A boundary between ancient subcontinents or “terranes” passes through the Niagara Peninsula and the Toronto region.
* The boundary between terranes is magnetized and guides migrating birds to form a major flyway.
* Fine banded rocks called “varves” are displaying yearly sedimentation layers, thus forming a fine-grained record of past conditions.
* The Scarborough Bluffs in eastern Toronto are a nearly complete record of the Pleistocene glaciations.
* Terrane movements are causing a visible buckling upwards and breaking of the the sedimentary rocks near Port Colborne.
* You can see a geological fault in the Rouge River Valley, exposed in the sediments on Twyn Rivers Drive.
* Much of Toronto’s geological history can be read in the Don Valley Brickworks, which went down to Toronto’s bedrock, the Georgian Bay Shale, which is fossil-bearing rock 440 million years old.
* A. P. Coleman, a Toronto geologist, proved that there had been several ice ages, not one, interspersed with warm interglacial periods. He thus disproved Lord Kelvin’s theory that the earth had been cooling since its formation.
* J. Tuzo Wilson, a Toronto geophysicist, helped to explain plate tectonics. (I knew that.) There’s a 400-million year cycle of forming and breaking up supercontintents, which is named the Wilson Cycle after him. (I didn’t know that.)
There are just a few small things that make me wish he could have afforded an editor for his first book. He’s a bit random about commas. And in one place he refers to 6 metres in a kilometer as a 6% grade. That’s either 60 metres in a kilometer (my guess) or a 0.6% grade.
I did a search for books by Nick Eyles and discovered that he has written a book on the geology of Ontario and has another one coming out this summer on the geology of Canada. Each one covers a bigger area and costs more.
