This is the third in the series of books on Western geology, following 'Basin and Range' and 'In Suspect Terrain'. John McPhee has the ability to write very readable and knowledgable essays about almost any subject that he chooses to examine, and these three books are very much a case in point.Whether you are seriously or just mildly interested in geology, this book is entertaining and infromative. There is enough family history (of his geologist companion), geological history etc. to keep you fascinated and to make for a good reading experience.