Six million years ago, a vast ocean--which scientists have named Tethys--vanished from the face of the earth. How could such a huge body of water simply disappear? More interesting, how is it possible for scientists to know with certainty that Tethys existed for a quarter of a billion years, a period that includes the entire Age of Dinosaurs and almost all of the Age of Mammals, right up to the point when our distant ancestors began to walk upright. Vanished Ocean tells the fascinating story of Tethys, offering an illuminating account of the scientific evidence for the ocean's existence. Renowned geologist Dorrik Stow describes the powerful forces that shaped the ocean; the marine life it once held and the rich deposits of oil that life left behind; and the impact of its currents on environment and climate. The story of Tethys is also a story of extinctions, floods, and extraordinary episodes such as the virtual drying up of the Mediterranean, before being filled again by a dramatic cascade of water over the straits of Gibraltar. In telling this story, Stow reveals how geologists and oceanographers have spent years proving the former existence of Tethys, from a remarkable series of clues locked away in rocks now exposed high up in mountain ranges and buried in sediments deep beneath today's oceans. Indeed, these myriad clues are now scattered from Morocco to China and from the depths of the Caspian Sea to the highest Himalayan peaks. Here then is the gripping story of the merging and splintering of continents, the rise and fall of mountain ranges, and an ancient, vast ocean that simply vanished from sight. It is a story that reminds us of the profound impact of oceans and their currents on the environment, climate, and life of our planet.