Factors affecting fossilisation

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Factors affecting fossilisation

Causes

  • Original composition
  • Energy Levels
  • Transport distance
  • Burial time
  • Oxygen levels
  • Size of sediment
  • Diagenesis

Effects

  • Many fossils are made of calcite or aragonite and are altered easily. Hard silica parts like radiolaria and some sponges may be preserved unaltered
  • High energy=fragments Low energy=complete fossils
  • Fossils break up in transport. (Abrasion and collisions)
  • Fast burial=whole body fossil, less chance of being eaten
  • Oxygen speeds up breakdown due to bacterial decay and encourages scavengers
  • Fine sedimet preserves better than coarse
  • Composition and acidity of groundwater percolating is important as it can dissolve or replace parts of a fossil

Overall summary

For exceptional preservation to take place:- Rapid burial in protective sediment like clay to protect hard parts from scavangers and weathering- Burial in a low energy environment- Lack of oxygen, anaerobic conditions- pH, decay is slowed at high acidity conditions

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