Unearthing the UnderworldUnearthing the Underworld reveals the hidden world of rocks " the secret keepers of past environments, of changing climates and the pulse of life over billions of years. Even the most seemingly ordinary stone can tell us much about the history of this planet, opening vistas of ancient worlds of ice, raging floods, strange, unbreathable atmospheres and prehistoric worlds teeming with life. Remarkably, many types of rock owe their existence to living