Larry Mantle talks with best-selling author and journalist Simon Winchester about his book that chronicles the finding of the first geological map of anywhere in the world. This map was of a hidden world lying beneath the surface of Britain that contained the rock strata, fossils and minerals. The finding of the map eventually led to an entire new science known as geology. Simon Winchester is the author of The Map That Changed The World: William Smith and the Birth of Modern Geology (Perennial-and imprint of HarperCollins), and previous author of The Professor and the Madman, and journalist who has written for many publications including the New York Times, HarperÆs, The Atlantic Monthly, The Spectator, among others.