Transcript 2/26/13

2/26/13
1.List the fossils in order from the
oldest to the youngest.
2. Explain why you know that is the
correct order.
Today I will investigate fossils in
sedimentary rock layers to gather
evidence of changing life forms.
What is a fossil?
• The trace or remains of an organism that
lived long ago most commonly preserved
in sedimentary rock.
How are fossils preserved?
• Petrification is a process in which minerals
replace an organisms tissues. One form
of petrification is called permineralizations.
Permineralization is a process in which the
pore space in an organism’s hard tissue is
filled with minerals. Replacement is a
process in which minerals completely
replace the tissues of an organism.
Petrified Wood
This piece of petrified wood was fossilized through replacement.
Types of Fossils
• Trace fossilsimprints filled
with sediments
and preserved
with rocks.
Mold and Cast fossils
Index fossils
Geologic Time Scale
Fossil Exit Quiz
1. Fossils found in the bottom layers of sediment are probably older than
fossils found in top layers because
a. the bottom layers are older than the top layers.
b. the bottom layers are younger than the top layers.
c. all of the layers are the same age.
d. the bottom layers have folded over the top layers
2. Any naturally preserved evidence of animal activity is called a(n)
a. trace fossil.
c. index fossil.
b. cast.
d. mold.
3. A mark or cavity made in a sedimentary surface by a shell or other body is a(n)
a. index fossil.
c. mold.
b. cast.
d. coprolite.
4. An ideal sequence of rock layers containing all of the known fossil and rock formations
on Earth is called the
a. geographic column.
c. geologic column.
b. relative column.
d. geologic sequence.