Designed for the roadside traveler, this book explains in detail the geologic history of Montana as seen through the window. It's great introduction to basic geomorphology and how the dramatic landscapes were formed. Each section is organized around a particular route, with black-and-white photographs complementing the amazingly detailed geologic maps. The highly readable text lets you know exactly how and when that butte on the horizon was formed and how it fits into the larger geologic picture.  (USW49, $20.00)