Robert J. Lillie

An author writing a book with a title like this one must first decide if he is writing about national parks, with some notes about plate tectonics along the way; or about plate tectonics, with ties to national parks along the way. Robert J. Lillie has gone the second route, writing a rather good introduction to plate tectonics that uses national parks, monuments, and seashores to illustrate the concepts whenever possible. And by "rather good" I mean that this introduction to plate tectonics is as good as anything I've seen. The book is written for an audience of better than average intelligence but without any particular prior knowledge of geology; probably college students in an introductory geology course, and not the one intended for education majors. The concepts are explained quite well, with a minimum of contemporary cultural asides, with excellent illustrations and diagrams and some good analogies. The diagrams include cross sections of plates and plate boundaries that really do a good job of making concepts like accretion, thrust faulting, and rifting more understandable. The analogies are workable (silica as a thickening agent, like flour in bread; various cookies and candies as models for various kinds of shield volcanoes, composite volcanoes, and domes; oceanic crust as a softball and continental crust as a soccer ball and one is much easier to float in water with than the other).

The first part of the book is a general introduction to plate tectonics and geology, and naturally most concepts are illustrated with photographs of national parks. The remaining sections tackle divergent plate boundaries, convergent plate boundaries, transform plate boundaries, hotspots, and the building of the North American continent. Each section has two or three chapters of its own, such as continental rifts, passive continental margins, and collisional mountain ranges under divergent plate boundaries.

The pitfall with a book of this nature is that the author is going to tend to emphasize things for which there are ready examples in national parks. However, Lillie has done a great job of finding national parks, monuments, or seashores to illustrate everything really important. Thus, the Precambrian mid-continental rift gets covered using national parks in the Great Lakes area that happen to expose the relevant rocks. Some of the less well-known national parks, such as Hot Springs in Arkansas and some of the Appalachian parks and East Coast seashores, get a fair amount of coverage simply because, for illustrating important concepts, they're what we've got. Very few of us will ever make it to Gates of the Arctic National Park :( but it gets coverage simply because Alaska is such a superb example of a mess of accreted terranes.

Nevertheless, there are gaps. There is no discussion of, for example, of the Mississippi Embayment and of the New Madrid earthquakes, I suspect because the topic is not absolutely essential and there are no national parks, monuments, or seashores anywhere nearby. In fact, intraplate earthquakes get almost no mention. A pet peeve is that Valles Caldera does not even appear in the index, which puzzles me a bit since it's a national preserve. Well, okay, a national preserve is not a national park, monument, or seashore. You see.

In general, though, I really like this book. The only thing that makes me hesitate to give it two thumbs' up is the rather steep $102 price tag for a paperback. Try to get a used copy; since this has the feel of a college introductory textbook, that may not be too hard. Or, according to Amazon, you can rent; another indication this is intended as a college textbook.… (más)