'Unfold a map of North America,' Keith Heyer Meldahl writes, 'and the first thing to grab your eye is the bold shift between the Great Plains and the Rocky Mountains.' In this absorbing book, Meldahl takes readers on a 1000-mile-long field trip back through more than 100 million years of deep time to explore America's most spectacular and scientifically intriguing landscapes. He places us on the outcrops, rock hammer in hand, to examine the evidence for how these rough-hewn lands came to be. We see California and its gold assembled from pieces of old ocean floor and the relentless movements of the Earth's tectonic plates. We witness the birth of the Rockies. And we investigate the violent earthquakes that continue to shape the region today. Into the West's geologic story, Meldahl also weaves its human history. As we follow the adventures of John C. Fremont, Mark Twain, the Donner party, and other historic characters, we learn how geologic forces have shaped human experience in the past and how they direct the fate of the West today.