Melvyn Bragg discusses the origin of the Earth. Ideas used to be very clear about its origins. Bishop Ussher, in 1654 arrived at an exact figure and specified it in his work Annalis Veteris et Novi Testamenti: He deduced that work on Planet Earth began at exactly 9am, on Monday 23rd October 4004 BC. The date was then printed in the margin of The Bible and preached from the pulpit, and right up to the nineteenth century to the left of ‘In The Beginning…’ was specified ‘Before Christ 4004’.Christian believers thought the creation story was solid as a rock…until the geologists arrived. First Hutton, then Smith, and then Lyell smashing away at orthodox belief in a way that made poor Ruskin quail, but in doing so they created a science. With Simon Winchester, author of The Map That Changed the World: the Tale of William Smith and the Birth of A Science; Cherry Lewis, geologist and author of The Dating Game: One Man’s Search for the Age of the Earth; John Cosgrove, Structural Geologist from the Royal School of Mines at Imperial College, London.