ed in 1972 with Roadside Geology of the Northern Rockies. Fourteen years later, the Big Sky portion of that book was updated to become Roadside Geology of Montana, a bright-yellow field guide that soon graced bookshelves across the state. Now, nearly 50 years after the first book, Mountain Press is releasing this completely revised full-color second edition that, like so many things in Montana, is big. But consider this: no other place in the world has such amazingly diverse and well-exposed rocks with such dramatic stories. For example, Montana lies at the northern edge of the Yellowstone caldera, the world's largest and most violent volcano. A lot of what the wold knows about dinosaurs and their demise came from fossils discovered in Montana's badlands. What began with panning for gold in the 1860s led to 1-mile-deep mines in Butte that supplied 60 percent of the world's copper by 1898. The world's largest ice age floods left ripples up to 50 feet high as Glacial Lake Missoula catastrophically drained from western Montana. With this book as your guide, you'll discover these and other world-class geologic features around every bend of the road.