This terrific day of activities offers the chance to handle fossils and precious stones. You can also pan for gems, try to identify rare minerals and make casts of fossils. And there are talks on subjects as varied as the exploration of Mars and the colour of dinosaurs. If one day isn't enough, the boffins from UCL, the Geologists Association and Rockwatch who are organising the festival, are also running field trips on the Sunday – leaflets available on the day will give more information. The Festival of Geology is free and there is no need to book.