Vanished ocean

"The Earth ever changes, and even vast oceans come and go. This is the story of such an ocean: how it grew to stretch in a wide belt across the Earth, the creatures that lived in it and at its shores, the changes it experienced, and how it shrank, broke up, and finally disappeared. Tethys, the geologists named it, after the sea goddess of Greek myth, daughter of Gaia and mother of great rivers. It began to form some 260 million years ago and vanished five and a half million years ago. How, then, do we know that it ever existed? Tethys has left us many clues: slivers of what used to be the sea floor, a whale graveyard, and oil--the oil of the Middle East on which so many rely today was formed from the decay of millions of tiny creatures that lived in its waters. Dorrik Stow, an oceanographer and geologist, tells how scientists have painstakingly pieced together these clues as he takes us through the life of Tethys." -- dust jacket flap.