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Year 10 Biology (Fossils (Different fossilisation environments (Amber…

- - - - Potassium dating
        
        Potassium decays into argon with a half-life of 1251 million years
      - Determines the actual age of the fossil in years
      - Radiocarbon dating
        
        Decay of C-14 into Nitrogen. has a Half-life of 5730 years
        
        After 70,000 years the amount of carbon 14 is negligible
    - - Index Fossils
        
        wide spread and present for a limited time on earth examples Trilobites and Ammonites
      - Tree Ring dating
        
        concentric rings on the surface of a cut tree, each ring equals one year
      - Fluorine Relative Dating
        
        the movement of Fluorine in water in the soil into the bone
      - Stratigraghy
        
        Layers of of rock which the top layers are younger than the bottom
  - - - when part of an organism is preserved with it's chemical composition being much the same as when it was alive. (Bones)
    - - when part of an organism is chemically changed into another mineral. older then 60 MYA
    - - when the dead organism decays and leaves a thin black deposit of carbon. Plant fossils are the most common example
    - - preserved remains of the imprint of the body, molds are an imprint left in the rock showing the outside of and organism
  - - - Solid plant sap, small organisms get caught in the sticky sap from trees. decomposition is stopped. the organism is perfectly preserved
    - - Where oil seeps out of the ground and onto the surface. traps animals.
    - - in the arctic circle, the land is permanently frozen. Bacteria and fungi which are involved in decomposition cannot survive
    - - no oxygen of bacteria can survive in peat. peat makes bones very soft
    - - Bacteria and fungi cannot live under very dry air conditions, soft tissue dehydrates and then fossilises and forms a mummy