Transcript Chapter 8 Concept Review

Chapter 8
Concept Review
The Rock Record
1. nonconformity

stratified rock resting on unstratified rock
2. unconformity

a break in the rock record
3. varve

a banded layer of sand and silt deposited
annually in a lake
4. law of crosscutting relationships

a fault or body of rock is younger than any
other body of rock it cuts through
5. radiometric dating

determining absolute age by comparing
radioactive and stable isotopes
6. disconformity

boundary between horizontal layers of
sedimentary rock, and younger layers over
an eroded surface
7. trace fossil

a fossilized mark formed by the movement
of an animal
8. uniformitarianism


current geologic processes are the same
as those that were at work in the past
It’s like what happened in the past is just
like what is happening now man.
9. law of superposition

sedimentary rock layers are younger than
layers below
10. index fossil

a fossil used to determine the age of rock
layers
11. Using rates of erosion to determine
absolute age is only practical for
geologic features

between 10,000 and 20,000 years old.
12. Why is radioactive decay used to
determine the actual age of rocks?

Radioactive decay happens at a relatively
constant rate.
13. The age of an object in relation to
the ages of other objects is its

relative age.
14. A break or crack in Earth’s crust
along which rocks shift their position
is called a(n)

fault.
15. In general, sedimentary rock is
deposited at the rate of

30 cm over 1,000 years.
16. A varve consists of a

coarse summer layer of sediment over lain
with a fine winter layer.
17. Almost all fossils are discovered in

sedimentary rock.
18. The study of fossils is called

paleontology.
19. Paleontologists examine coprolites
to

Learn about the feeding habits of
dinosaurs.
20. Geologists use index fossils to

locate rock layers that contain oil and
natural gas deposits.
The End !!!