How do we date rocks?

I've been asked to explain the secrets of how we date rocks... not that it's particularly secret, but it can seem mysterious if you don't know how it's done. The key point point is that most of the time we're not actually dating the rocks, as such... we're correlating them. With fossils, or whatever tools we have at our disposal! Presented by Joe Botting, independent palaeontologist and Honorary Research Fellow at the National Museum Wales. ---------------------------------------------------------------------------------------------------------------------------------------------------- Channel Membership: to support the channel for £3.99 per month, please investigate the 'join' button underneath the video. You can expect 2-3 extra videos per month, showing current research, related mainly to the Ordovician Castle Bank Biota.