Today I resumed my glacially slow progress through Canada Rocks: The Geologic Journey. I say glacially slow because the book, aside from being as large as a continent, is also as dense as rock! Not that it is especially difficult reading, it just contains a tremendous amount of information, both written and visual. I’ve learned that despite being raised on science, and even having taken a geology course in university, I had only the faintest notions of how our planet actually works. I somehow had the idea that the earth’s mantle was liquid. Nope. It’s solid rock. That’s not to say it’s stationary—it moves and circulates by convection—but it’s composed of solid, hot rock. And there is more going on in the mantle than that. Remember what they told you in school about the inside of the earth? It probably looked something like this:
In reality, it’s more like this:
You might be wondering what those tentacly things are. They are plumes of molten rock rising from the hot outer core (gold) through the mantle (yellow), and sometimes erupting at the surface to build more crust, or creating currents that move continents around. The green in the picture is cool, solid ocean crust subducting under lighter, continental crust and free-falling to the center of the earth.
I’m finding it all fascinating, but I do have one quibble with the book. Sometimes the diagrams (of which there are many) are pages away from the text that refers to them. The worst example is a collage of pictures of different types of metamorphic rock that appears a full 12 pages before the relevant text! This is not just a hassle, it can be confusing when I look at a diagram before I know enough to understand it. It’s surprising to find this kind of problem in a book of this quality (and price!). I’ll just have to stick to the text and look at the figures as they are mentioned.
On the positive side, the book contains very interesting one- and two-page spreads on famous geologists and their discoveries, and on the methods of modern geology (such as ocean drilling). I learned that Canadian geologist John Tuzo Wilson, who was instrumental in explaining plate tectonics, came by his love of rocks honestly. His mother, Henrietta Tuzo, was a famous mountain climber, whose accomplishments included being the first person to summit one of the ten peaks above Moraine Lake in Banff National Park. The mountain is now named after her. How appropriate that it was her son who helped explain how it got there.