Fossilisation

Fossilisation is a process that turns a once living plant, animal or even footprint into a solid mineral or rock that can be found by fossil hunters millions of years later.

Even though we find many thousands of fossils in a place like Charmouth, the chances of a fossil being formed are very small indeed. The hard minerals that make our bones and the shells of sea creatures are more likely to dissolve than to remain together long enough to be preserved as a fossil.

The chances of a fossil forming are far greater if the plant or animal remains are buried quickly, or happen to fall into an area with very little oxygen (like the bottom of a deep lake or sea). Luckily for us both of these things happened in the Lower Jurassic sea around what was to become Charmouth.

Ancient ammonites, belemnites, shells and skeletons either had their hard parts gradually swapped for minerals or left a cast in the mud to be filled by hard minerals as time passed.

The fossilisation process turned the relatively fragile creatures and plants from the Lower Jurassic into hard fossils that withstand the power of the sea when washed from the cliffs and survive on the beach for us to find

Film produced by Osis (www.osisdesign.co.uk)