Chapter 29 Studying the Past

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Chapter 29 Studying the Past

• Paleontology
• Fossils
• Lets talk about the types

• The study of life that existed in prehistoric
  times
• Preserved remains of a plant or animal

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• Original remains
• Replaced remains

• Original and unchanged remains of a plant or
  animal preserved in a rock Amber is an example
  (animals caught in sticky tree sap
• Minerals in groundwater replace the decaying
  plant or animal like petrified wood!

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• Cast
• Mold

• A copy of the original fossil
• A depression in a rock of the original fossil

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• Trace fossils

• Impressions such as footprints, tracks, burrows
  or bite marks

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Relative Time

• Relative dating
• Strata -

• Placing events in a sequence in which they
  occurred
• Layers of the Earth

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Basics..

• Law of Superposition

• The oldest layers of rock will be on the bottom
  and the youngest strata or layers will be on top

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• Principle of Cross Cutting Relations

• The igneous intrusion that cuts across layers of
  rock is always younger than the layers it cuts

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• Law of Embedded Fragments

• The fossils or fragments of rock that are
  embedded in a layer are OLDER - because they
  existed before

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• Correlation

• The matching of rock layers

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• Correlation

• The matching of rock layers

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• Unconformity

• A missing layer in the rock strata

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Absolute Time

• Radioactive Decay
• Half-Life
• Radiocarbon Decay Carbon 14 dating

• The decay of radioactive isotopes, emitting tiny
  particles
• The time it takes ½ of a radioactive atoms to
  decay
• Using the isotope Carbon 14 to date organic
  material half life of c-14 is 5,730 years

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