Toronto Rocks: The Geological Legacy of the Toronto Region

J.H. Galloway is a professor of geography at the University of Toronto
and the author of The Sugar Cane Industry.

This introduction to the geology of the Toronto region assumes that
readers are new to the study of geology. There are numerous photographs
and diagrams. Indeed, at least half the space is devoted to
illustrations of one sort or another.

Eyles divides the geological history into four “layers,” each layer
representing an era from the Precambrian to the present. He includes a
brief review of continental drift (“plates in motion”), which gives
him the opportunity to explain earthquakes and volcanoes before moving
on to a discussion of each era. He devotes two pages to the Precambrian,
touching on the mineral wealth of the Canadian Shield. The Paleozoic is
treated at greater length, with an emphasis on the fossil record, the
Niagara Escarpment, and Niagara Falls. The Pleistocene, which
encompasses the last two million years or so of ice ages, is the longest
section and perhaps, for those interested in the physical landscape of
the Toronto region, the most useful. Readers may be interested to know
that we can expect the next ice age in about 5,000 years. In the fourth
section, Eyles comments on the consequences of urbanization on the
Toronto region’s hydrology and its wildlife habitats. Interspersed
throughout the work are brief notes on pioneer geologists Alfred Wegener
and Louis Agassiz and astronomer Milutin Milankovitch. Two local
scholars receive special mention: geophysicist J. Tuzo Wilson and
geologist Arthur Philemon Coleman, both in their time professors at the
University of Toronto.

Toronto Rocks offers an interesting look at the geology around and
beneath Toronto. The language is straightforward, and the numerous
illustrations are very helpful. There is a list of further reading for
those who wish to know more.