Customer Reviews:
 We live on the United Plates of Canada April 3, 2008
Stephen A. Haines (Ottawa, Ontario Canada)
2 out of 2 found this review helpful
What is now "North America" has had a long, nomadic career. To palaeogeologists, "North America" began forming about 2.7 billion years ago as part of a large landform known as "Kenorland". Kenorland was well south of the Equator at the time - in fact it seems to have partly enclosed the South Pole. From that distant beginning, "Kenorland" was joined by other continents, notably Europe, Australia, Siberia and "Baltica" to form a supercontinent geologists call Rodinia. Over time, and renamed "Laurentia", the landmass was pushed across the face of the globe in a northwesterly direction. It is still moving.
Nick Eyles and Andrew Miall have chronicled the movements of our mobile foundation in this stunning volume. Superbly written and lavishly illustrated, the authors explain why Canada's situation brought it to the forefront of geologic science. Nearly everything that is known about plate tectonics, in both a broad view and in countless details is found here. As they note, many Canadian geologists have been in the lead in understanding and explaining how the Earth functions.
Although at first glance, this book appears to be a textbook on geology, "Canada Rocks" is far from that. The title, of course, is the first indication this is going to be a book for everybody. Is "Rocks" a noun or a verb? Well, yes. The first two chapters depict the formation of our planet and what forces are involved in shaping it. They show how continental plates are formed and explain why it's important to understand that. It is an ideal introduction to what follows. The third chapter presents the formation and movements of the first continents and supercontinents and how we know of their former existence. "Former" is important, because those land masses laid down the base on which we stand.
The "Canadian" Shield is the visible surface for this continent. Stretching across vast expanse, from the Arctic into northern Mexico, it overlies the "North American Craton" of deeper, older rock formations. That craton comprised the proto-continent Laurentia driven over the globe by spreading oceans. As it travelled, it encountered other landmasses at its edges, making new supercontinents before breaking off on another phase of its journey. Over 600 million years ago, Laurentia broke free for a time. Its new freedom carried a price - the wearing down of old mountains and the intrusion of a massive sea. Shallow and warm, that sea was invested with life, leaving an extensive fossil record.
Laurentia wasn't finished, however. Forces pushing it about on the globe were being applied everywhere in varying degrees. Eastern Canada was built when the Atlantic Ocean's central rift pushed it away from Europe and Africa. The map of the Atlantic coast of North America resembles a patchwork quilt of formations originating far from their present location. The breakup of Pangaea by the Atlantic Ocean wasn't as "clean" as today's shorelines suggest. The eastern region resulted from pieces of many continental plates broken off and interspersed with other bits arriving later. It is in describing this melange that the authors introduce John Tuzo Wilson, the pioneer who first recognised what bizarre patterns of trilobite fossils implied. In a similar manner, western Canada, today a glorious visage from any vantage point, was "built" by the arrival of several smaller land bodies. Geologists in the 19th Century wondered why mollusc and other sealife fossils were appearing in rocks 500 kilometres from any coast. Later analysis indicated they had arrived from far out in the Pacific many millions of years ago. "Sub-continents" Wrangellia and Stikinia rammed into the western edge of the Craton, pushing up mountains and delivering the fossils to locations now far inland.
The authors further explain how all this geologic activity has meaning for us today. Gold and other precious metals are exploited and a new diamond industry is emerging. Mining is a major Canadian industry, but not all of it is due to shifting continents. Sudbury, Ontario, is home to several mining companies, which are utilising a resource delivered from space. All that nickel, copper and zinc arrived in a meteorite smacking the Craton over a billion years ago. The ice sheets pushed Canadian topsoil into what is now the United States, but they also formed the seaway that lets the agricultural and mining products float to the sea instead of travelling overland.
While all this information and depictions of movement over time may sound intimidating, the authors have put a great deal of effort into making it understandable. The illustrations, whether drawings or photographs, provide excellent supportive material. Each chapter has a useful "Further Readings" appended, allowing the reader to expand on what's been learned. This is more than merely an explanation of how Canada and the rest of North America formed. It's a knowledge investment any family will benefit from. [stephen a. haines - Ottawa, Canada]
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