TV reporter Clive Gunnell is at Charmouth Beach in Dorset with specialist fossil hunter and exhibitor Barney Hansford. The beach is part of the Jurassic World Heritage Coastline and a Site of Specific Scientific Interest (SSSI). Paleontologists study fossils and date them to a specific geologic time scale (GTC) of supereons, eons, eras, periods, epochs and ages. Fossils such as ammonites are known as index fossils because they may be dated to a specific GTC.