This is a very handy book. It's arranged by road name and by stretch of road--if you find yourself on, say, I-70 westbound from Denver, go to the table of contents and you'll quickly find something like "I-70, Denver to Dillon Reservoir." Go to that section and you'll find a small map, geological diagrams, and probably a photograph. There's also an introductory chapter that gives an overview of Colorado geology and geological history, as well as very clear explanations of geological terms.Driving on Colorado highways you see some pretty amazing rock formations, and visitors to the state are always asking about them. This book will tell them (and you) anything you might want to know, and explain it clearly. I keep my copy in the car, and consult it often.