Notes: Rocks and Fossils

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Notes Rocks and Fossils

• February 18, 2004

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• Rocks are made of mixtures of minerals and other
  materials
• Igneous Rocks form when molten material cools
  and hardens below or on Earths surface
• Sedimentary Rocks form when particles of other
  rocks or the remains of plants and animals are
  pressed and semented together
• Metamorphic Rocks form when an existing rock is
  changed by heat, presure, or chemical reactions

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• Petrified Fossils fossils in which minerals
  replace all or part of an organism
• Mold a hollow area in sediment in the shape of
  an organism of part of an organism
• Cast a copy of the shape of an organism
• Other Types of Fossils Carbon film, trace
  fossils, and preserved remains

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• Relative Age its age compared to the ages of
  other rocks
• Absolute Age the number of years since the rock
  formed
• Law of Superposition ub horizontal sedimentary
  rock layers the oldest layer is at the bottom.
  Each higher layer is younger than the layer below
  it (relative age)

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