1. Relative Dating

2. DO NOW MONDAY
What is an index fossil?
What is it used for?

3. Learning Targets-MONDAY
Explain relative dating using index fossils.
Identify the sequence of rock layers using the Law of Superposition.

4. Law of Superposition
Younger rock layers are above older ones of the rock layers have not been disturbed.
But what if they have been disturbed?

5. Principle of Inclusion
When pieces of rock/fossils, etc. are included in a layer of rock, then the pieces are older than the layer of rock.
The pieces had to exist before they could be included in the layer of rock.

6. Cross-Cutting Principle
If many layers of rock are “cut” by a fault, then the fault line must be younger than the layer of rock.
The layer of rock had to have been there first in order to have been cut by the fault line.

7. DO NOW TUESDAY Which letter is pointing to the oldest layer?
Which law of relative dating explains how we know? C. B. A.

8. Learning Targets- TUESDAY
Explain relative dating using index fossils.
Identify the sequence of rock layers using the Law of Superposition.

9. Snickers Relative Dating Activity
1. Draw a cross-section of your snickers bar on your sheet. As you draw, be thinking about which layer formed first, second, and so on.
2. Label (on your drawing) the four main layers of your snickers bar.
3. Answer questions 2-4 on your sheet.
4. Cut a fault into your snickers bar.
5. Redraw a cross section of your snickers bar.
6. Answer question 5 on your sheet.
7. Do number 6 on your sheet.

10. 1. 2. 3. Superposition: Layer on top Is always youngest Inclusions
Caramel and Peanut Layer
Nougat
Top chocolate
Bottom chocolate layer
There are 3 Rules that allow scientists to date rocks
Relative Dating
3 Laws of Relative Dating
Superposition: Layer on top Is always youngest 1.
LEARNING CHECK 1
Which layer on your snickers bar is the youngest and which is the oldest
2. Cross-Cutting Principle
Any fault or magma plume that cuts across a rock is always younger than the rock it cuts across 2.
LEARNING CHECK 2
Is the fault you cut into the snickers older or younger than the snickers rock around it?
Fault 3.
3. Inclusions
Pieces of rocks that are included in a rock layer are OLDER than the the rock layer.
LEARNING CHECK 3
What are the inclusions in your snickers bar? Are they older or younger than the caramel layer itself?
Inclusions
1. Cut the chocolate off of one side of your snickers bar
2. Draw and label the four main layers of your snickers bar
3. Cut a fault into your snickers and piece it back together off center
Redraw
4. Tilt one half of your fault and stick snickers back together. Redraw
5. Point out inclusions
6. Weather and erode top couple layers of snickers. Leave angles! Redraw
7. Now use bit of frosting to add another layer of sediment…
add to drawing and label unconformities

11. EXIT SLIP TUESDAY
Give the sequence of the numbers in the diagram below
from youngest (on top) to oldest (on bottom.)