It is a challenge, to say the least, to try to "teach yourself" geology. This book is unsurpassed in its ability to explain the many basic principles necessary to understand the earth and how it works. It goes way beyond park by park geological descriptions. It teaches the reader to understand the geology and does so in a way that makes it a real page-turner. (I'm not kidding!) Unlike McPhee's books, it is filled with illustrations and diagrams explaining subduction, converging plate boundaries, uplift and the many other concepts that are essential to being able to understand and appreciate the past and on-going history of the geology of the United States. Unlike the "Roadside" series, it does not use terms and vocabulary without explaining their meanings and significance. Anyone can understand and follow Lillie. I would give a lot to be one of his students. He uses our national parks to illustrate his lessons and scores an unqualified success. In short, this is a stunningly beautiful book that makes you want to jump in the car and head out to see our national parks and monuments, with confidence that, once there, you will truly understand the processes that created their natural beauty. After much searching for a layman's guide to geology, I cannot recommend this book highly enough.