Good Morning!

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Good Morning!

• 1. Complete your warm-up What happens at a
  convergent boundary? Be specific.
• 2. Have out your Venn Diagram. You may have it
  pasted in your notebook, I am coming around to
  check for completion.
• 3. Copy tonights HW Matching half sheet
• 4. Read silently.

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10 minutes to finish your chart.
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A Trip Through Geologic Time

• NOTE Under Kinds Of Fossils you need to ADD
  Trace Fossil.

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A Trip Through Geologic Time
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Fossils

• Fossils are traces or remains of ancient life.
• Fossils show how life has changed over time.
• Scientists who study fossils are paleontologists.

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Fossils

• Fossils are usually found in sedimentary rocks.

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Kinds of Fossils

• Petrified Wood stone fossil of a tree.

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Kinds of Fossils

• Molds and Casts
• Mold is a hollow area in the shape of an
  organism.
• Cast is a copy of the shape of an organism.

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Kinds of Fossils

• Carbon Films an extremely thin coating of carbon
  on rock shows the soft parts of the organism.
• Trace Fossils evidence of the activities of
  ancient life. Ex footprints, animal trails,
  feces, or animal burrows.

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Kinds of Fossils

• Original Remains actual body parts of an
  organism. May form in ice (best preserver), amber
  (sap), or tar.

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Why Study Fossils?

1. To learn what past life forms were like.
2. To classify organisms in the order in which they
   lived.
3. All the fossils found on earth make up the fossil
   record.

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Fossil Record

• Provides evidence about the history of life on
  Earth.
• Shows how different groups of organisms have
  changed or evolved while others became extinct.

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Remember!

• The fossil record is incomplete most organisms
  do not become fossils.

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Other evidence show change in life and the
environment

• Tree Rings- show weather patterns
• Ice Cores- show how the atmosphere has changed
  over time

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Finding the Age of Rocks Through Rock Dating
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D A T I N G
R O C K
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Ages of Rocks

• The relative age of a rock is its age compared to
  other rocks. Use words like older or younger
• The absolute age of a rock is the number of years
  since the rock was formed.
• Ex 358-360 mya
  

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Rock Joke!!

• What does a rock want to be when it grows up?
• A Rock Star!!

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The Position of Rock Layers

• It can be difficult to determine a rocks absolute
  age. So scientists use the law of superposition.
• According to the law of superposition, in
  horizontal sedimentary rock layers the oldest
  layer is at the bottom. Each higher layer is
  younger than the layers below it.

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Rock Joke!!

• How do rocks wash their clothes?
• The Rock Cycle!!

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Other Clues to Relative Age

• Clues From Igneous Rock
• Lava that cools at the surface is called an
  extrusion. Rock below an extrusion is always
  older.
• Magma that cools beneath the surface is called an
  intrusion. An intrusion is always younger than
  the rock layers around and beneath it.

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Other Clues to Relative Age

• Faults (a break in the rock) are always younger
  than the rock it cuts through!
• Unconformities An unconformity is a gap in the
  geological record. New rock forms on top of
  eroded rock

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Using Fossils to Date Rocks!

• Scientists use index fossils to match rock
  layers.
• An index fossil must be widely distributed and
  represent a type of organism that existed only
  briefly.
• They tell us relative age of the rocks

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The Trilobite

• One example of an index fossil is a trilobite.
• Trilobites were a group of hard-shelled animals
  whose bodies had three distinct parts.
• They evolved in shallow seas more than 500
  million years ago.

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Fossil Study Guide