Themes > Science > Paleontology / Paleozoology > Fossils And Fossilisation > How are fossils formed?

Fossilisation is the process of forming a fossil. Fossilisation of a whole plant or animal is very rare. Often only the hard parts of plants, such as seeds and wood, and the bones and teeth of animals become fossilised. Most animals and plants that become fossilised had either lived in water or were washed into it after they died. After this, the following process takes place:
  1. the soft parts of the plant or animal rot away, leaving the woody parts or bones, teeth or shell
  2. the hard parts are buried under layers of sediment, sand, mud or lime, usually in a lake, swamp or cave
  3. the sand, mud or lime that covered the plants and animals is turned into sandstone, shale or limestone
  4. over millions of years, the sandstone, shale or limestone is buried very deep and is compressed by the layers above, becoming hard rock
  5. eventually the parts of the plant or animal which survive, become soaked with minerals and undergo a chemical change which creates fossils. 


Information provided by: http://www.austmus.gov.au