Transcript What Happened Before?

What Happened Before
Exploring Fossils with
Mike Baldwin
5th Grade Science TEKS
(5.11). The student knows that certain
past events affect present and future
events. The student is expected to
(A) Identify and observe actions that require
time for changes to be measurable,
including growth, erosion, dissolving,
weathering, and flow;
(B) Draw conclusions about "what happened
before" using data such as from treegrowth rings and sedimentary rock
sequences
What is a fossil?
Something left by a plant or
animal that lived long ago!
What must happen for a fossil to
form?
For a fossil to form, something
must get buried!
Fossilization
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).
Sedimentation
As 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.
Erosion at work
Rain, 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!
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.
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
Dinosaur tracks are an example of
trace fossils
Explain how the trace fossil of the
dinosaur foot could be formed.
1.
2. Sedimentation:
3. Rock formation:
4. Erosion:
Erosion exposes rock layers so that
fossils can be discovered.
Rock layers can move!
Sometimes a fault can change the
location of a rock layer.
Answer the questions on your
worksheet about the stratigraphic
column below.
Vocabulary
Fossil
Strata
Stratigraphic column
Trace fossil
Index fossil
Sedimentary rock
Erosion
The End
Mike Baldwin