What Happened Before

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What Happened Before

• Exploring Fossils with
• Mike Baldwin

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5th Grade Science TEKS

• (5.11). The student knows that certain past
  events affect present and future events. The
  student is expected to
• Identify and observe actions that require time
  for changes to be measurable, including growth,
  erosion, dissolving, weathering, and flow
• Draw conclusions about "what happened before"
  using data such as from tree-growth rings and
  sedimentary rock sequences

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What is a fossil?

• Something left by a plant or animal that lived
  long ago!

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What must happen for a fossil to form?
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For a fossil to form, something must get buried!
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Fossilization
Erosion at workRain, wind, earthquakes, freeze
and thaw all work toward erosion. The mountains
that were built up are worn away over time. Our
fossil once again sees the light of day!
To start with an animal or plant must die in a
location where it will not decay too rapidly (In
water or where it will be buried quickly).
SedimentationAs time passes sediments bury the
organism. The faster this happens the more likely
fossilization will occur. Land and mud slides
definitely help.
As the sediments continue to pile on, the lower
layers become compacted by the weight of the
layers on top. Over time, this pressure turns the
sediments into rock.
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Index Fossil

• Index fossils are fossils used to identify
  geologic time periods. Index fossils are
  important because, although different rocks may
  look different depending on the conditions under
  which they were laid down, they may include the
  remains of the same kinds of fossils.

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Trace Fossil

• Trace fossils are structures preserved in
  sedimentary rocks that record biological
  activity. Strictly defined, trace fossils must
  reflect both the anatomy of their maker in some
  way, and be the result of behavior

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Dinosaur tracks are an example of trace fossils
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Explain how the trace fossil of the dinosaur foot
could be formed.
1.
2. Sedimentation
3. Rock formation
4. Erosion
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Erosion exposes rock layers so that fossils can
be discovered.
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Rock layers can move!





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Sometimes a fault can change the location of a
rock layer.
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Answer the questions on your worksheet about the
stratigraphic column below.
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Vocabulary

• Fossil
• Strata
• Stratigraphic column
• Trace fossil
• Index fossil
• Sedimentary rock
• Erosion

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The End

• Mike Baldwin