3. Remind me again…
What is the difference
between relative-age
dating and absolute-age
dating?
4. What is a fossil?
Fossil: The trace or
remains of an organism
that lived long ago.
Are all organisms
preserved as fossils?
There are three types
of rocks, do you
remember their
names?
Which type of
rock do you
think most
fossils are
preserved in?
Why?
5. If fossils are organisms of the
past, how can they help us tell
about the history of the earth?
6. Index Fossils
A fossil that is found in the
rock layers of only one
geologic age
They are found in rock
layers around the world
12. Almost one half
(approximately 2 billion
years) of earth’s history
can be seen at the Grand
Canyons National Parks
through the different rock
layers found there
It is one of the best places
in America to see this
much history
13. If you’re looking at a rock
sample, which layer would be
the oldest?
14. This is the law of SUPERPOSITION: in sedimentary rock
layers, the rocks are laid out fairly flat, where the oldest is on
the bottom and the youngest is on the top.
15. If nothing disturbs the rock layers they will
remain the same. If the rock layers are
disturbed, they may end up like this:
16. What things that can disturb rock layers?
•Folding or tilting from shifting plate tectonics
•Volcanic intrusions
•Faults
