A rock composed of particles smaller than 1/256mm. It can be distorted easily (it is plastic) when wet. Related Articles: Some fossil finds in the Hastings areaGeo junkets (Part 1): New Zealand, North IslandCaught between two mass extinctions: The rise and fall of DicroidiumBook review: A Guide to Fossil Collecting on the South Dorset Coast, by Steve Snowball and Craig Chivers, with illustrations by Andreas KurpiszBook review: Trilobites, Dinosaurs and Mammoths: An introduction to the prehistory of the British Isles, by James McKay (for the Palaeontological Association)« Back to Glossary Index