This tenth book in the Geology Underfoot Series offers an inside view of the uniquely enigmatic landscape west of the Continental Divide in Colorado. In this arid region where mountain snowmelt drains through deep canyons en route to the Gulf of California, the crumpled gneisses of the Colorado Rockies meet the famous red rocks of the Colorado Plateau. Nothing is simple here, with rich metal ores filling fractures of supervolcanoes, small mammals flourishing in a world of giant dinosaurs, and rivers shifting course with each new uplift or eruption of lava. Join a team of geologists as they use clear prose, concise illustrations, and dramatic full-color photographs to tell the deep-time stories of 26 geologic sites, including four giants of the national park system: Mesa Verde National Park, Black Canyon of the Gunnison National Park, Colorado National Monument, and Dinosaur National Monument. Fossil collectors, rockhounds, hot potters, coal miners, and adventurers of all ages can use this guide to better understand the geology underfoot throughout Colorado's beautiful Western Slope.