Name: _______________________________ Date: _________________ Block: _______
Relative Dating
You are an expert in relative dating techniques. You need to explain, using the chart below, the
relative age of the fossils in relationship to the other fossils. Answer each question. Once you have all
of your answers recorded, WRITE YOUR PARAGRAPH RESPONSE in your NOTEBOOK.
1) Using the letters printed on the left, what is the
order of the rock layers from youngest to oldest?
O-R-G-A-N-I-S-M
2) What is the youngest fossil? How do you know?
The youngest fossil is the Foraminniferan. I know this
because it is in Layer O, the youngest layer at the top.
3) What is the oldest fossil? How do you know?
The oldest fossil is the Tribrachidium. I know this
because it is in layer M, the oldest layer at the bottom.
4) An index fossil is a fossil that is found only in one
layer of earth and can be used to date layers.
What fossils would be good index fossils? Explain
why.
The Foraminniferan would be a good index fossil
because it shows only in layer O at the top.
5) What fossils would be bad index fossils? Explain
why.
Some bad index fossils would be the Brachiopod,
Diplomytus, Crinoid, and Trilobite fossils because they
occur in more than one level. This would not accurately
indicate the age of a fossil solely based on its location in
the rock strata.
Name: ____________________________ Period ______
Principles of Geology:
Law of Uniformitarianism: The way things occurred in the past are likely the same way things occur today.
(example: rivers flow downhill today so they probably flowed downhill in the past also)
Law of Superposition: The youngest layer of rock is on the top. The oldest layer of rock is on the bottom
Law of Original Horizontality: All sedimentary rocks are deposited flat initially. If you find them at an angle,
they have been moved
Law of Cross-cutting relationships: igneous rocks or faults that “cut” into other rocks are the youngest.
(the “other rocks” had to be there before they could get cut by anything)
Sand
1. Which of these layers is the youngest? _________ How can you tell? _________
It's the youngest because it is on the top layer of the strata
_________________________________________________________________
The Law of Superposition
What principle of geology does this relate to?____________________________
2. When did layer “4” occur? After 1, 2, & 3 , before 5 How can you tell?
___________________
Because layer 5 is on the top, however 4 cuts through 1, 2, and 3.
________________________________________________________________
Law of Cross-Cutting Relationships
What principle of geology teaches that concept? ________________________
3. What happened to these layers of rock (if anything)?
They've been moved
___________________________________________
Which principle of geology did you use to determine what
Law of Original Horizontality
happened? ____________________________
The bottom layer
4. Which layer was there first? _________________ Write down
everything that happened to these layers of rock after ALL of the
layers were deposited. (Don’t forget erosion by the
The rocks were originally deposited flat, however they've
river)_________________________________________________
been moved. Erosion has taken off the top layers of the rocks
______________________________________________________
and valleys/hills have been created.
_____________________________________________________
5. What happened first in this picture (the igneous pluton D or the
D
earthquake fault line E)? _______
D
Which rock layer was put down last (A, B, C, or D) ________
Why do you think rock D is sticking out above the ground (like a
There was enough force to break through the top layer.
hill)? _________________________
Which way did the rocks on the right move? (upward or
Downward
downward)? _________________
Name: ____________________________ Period ______
6. This is a picture of a fault line that is a result of an earthquake causing
the land to break and slip. The one on the right side, slipped downward.
Which happened first? (The lighter layer outlined by dashes or the fault
line)?Lighter
_______________
layer formed Which principle of geology helps you figure
The Law of Horizontality
that out? ___________________________________
7. Which happened first (the Coal layer, the Banana
Sandstone, or the erosion of Deadman’s canyon)?
_______________________________________
The COAL layer
What happened to the top of the curvy rocks beneath the
Erosion, plate movement, etc.
Banana Sandstone? ____________________________
Why are the rocks on the bottom folded but the top ones
are not? What do you think could have caused this?
There was likely erosion and plate movement that caused
________________________________________________
the plates to shift. The layers were then deposited flat again.
_______________________________________________
8. What do you think caused the layers on the bottom to tilt upward?
Tectonic plate movement at a convergent boundary - or upward shift
______________________________________________________
They've been deposited after
Why are the layers on top not tilted? ________________________
the event occured.
______________________________________________________
Which law states that rocks are always deposited flat first?
Law of Horizontality
______________________________________
9. This rock has a vein of lava rock that squeezed it’s way in through the crack.
Which principle of geology would help you to know that the vein of lava rock is
The Law of Cross-cutting relationships
the youngest? ________________________________
10. Which “blob of lava” (pluton) was in this area first
A
(A, B, or C)? _________ What is your evidence? __
The continual formation of land built up, creating
__________________________________________
the volcano. Also, the older rock is lighter.
__________________________________________
A B C
