Dirt, soil, call it what you want--it is the root of our existence, supporting our feet, our farms, our cities. In this natural and cultural history of soil that sweeps from ancient civilizations to modern environmental calamities, earth scientist Montgomery explores the idea that we are--and have long been--using up Earth's soil. Once bare of protective vegetation and exposed to wind and rain, cultivated soils erode bit by bit, slowly enough to be...