How Fossils are Formed

How fossils are formed.

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  • Created by: Jelena
  • Created on: 14-05-13 15:42
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  • How Are Fossils Formed?
    • Mold, Cast, and Imprint Fossils
      • 1.An organism is buried
      • 2. Its remains decay, leaving an empty space
      • 3. A mold retains its space
      • 4. Sand or mud can fill the mold, leaving a cast
      • 5. Imprints of plants or fish in soft mud or clay have been found in sedimentary rock
    • Replacement
      • 1. Original material dissolved by water
      • 2. Replaced by a different mineral material
      • 3. Replacement is common in hard materials = bone, shell, wood
    • Permineralization
      • 1. Happens when ground water w/ dissolved minerals gets into pores + cavities of bone, wood, or shell
        • 2. Minerals deposited make stony fossils that still have some original material
      • 3. Bones, teeth, and marine organisms are preserved this way
    • Original Preservation
      • Happens when an organism is preserved and original material stays the same
      • 1. Mummification: organisms are dried and preserved in desert caves or beneath desert sand
      • 2. Amber: insects are trapped in stick tree sap and are preserved when the sap hardens
      • 3. Tar seeps: animals get trapped in tar seeps formed by thick petroleum oozing to the earth's surface and were preserved as they were covered in tar
      • 4. Freezing: organisms buried in frozen oil and ice don't decay
    • Carbonization
      • 1. Soft parts of organism were compressed and heated
      • 2. N, O, H, etc. decay, carbon is left behind
      • 3. Common in plants, soft bodied organisms, and fish

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