Fossil Preservation Basic
- Created by: Mellissa True
- Created on: 10-02-13 12:32
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- Basics of Fossils
- Only Hard Parts of Organisms will be Preserved
- Shells or external skeletons made of calcium carbonate (CaCO3)
- Internal Skeletons; usually vertebrate bones and teeth made of calcium phosphate
- Woody material from some plants in the form of lignin
- Carbonisation
- This affects organic substances such as lignin and Chitin.
- During compaction all elements except carbon leave the the plant
- This creates a black imprint left by the fossil plant.
- In some rare cases soft body tissue can leave a thin carbon film and preserve more detail than hard parts
- Petrification and Replacment
- This happens as mineral solutions seep through a sediment
- Sometimes the fossil material is strengthened by the new minerals
- In some cases the original material is dissolved away and completely replaced by the crystallization of a new mineral
- The commonest petrifying and replacing minerals are those that act as cements in sediments.
- Example:Calcite and Silica
- In rarer cases fossil material may be replaced by pyrite, haematite or limonite
- This happens as mineral solutions seep through a sediment
- Mould And Cast
- Organism (hard Parts) buried in sediment and original material dissolves to leave an exact mould of itself
- New mineral infills mould to produce a cast. Both mould and cast are fossils and each shows detail of original organism
- Organism (hard Parts) buried in sediment and original material dissolves to leave an exact mould of itself
- Only Hard Parts of Organisms will be Preserved
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