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  • Fossils
    • Gradual Replacement by Minerals
      • 1. Hard parts don't decay easily so can last a long time when buried
        • 2. They eventually replaced by minerals as they decay, forming a rock like substance.
    • Casts and Impressions
      • 1. Sometimes fossils are formed when an organism is buried is soft material like clay.
        • 2. The clay later hardens around it and the organism decays leaving a cast.
          • 3. Things like footprints can be pressed into these materials when soft, leaving an impression when it hardens
    • Preservation
      • Amber - no oxygen or moisture so decay microbes cant work.
      • Glaciers - too cold for decay microbes to work
      • Peat bogs - too acidic for decay microbes to work.
    • How life began
      • There is a lack of  valid and reliable evidence for how life began
        • Scientists believe this is because there were many soft bodied organisms so the fossil record is incomplete.
          • some fossils will have been destroyed by geological activity


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