Dating Rock Layers

1
Dating Rock Layers

• How to tell how old the layers of rock are.

2
What is Age?

• There are 2 kinds
• Absolute Age The number of years since the rock
  formed. (150 million years old, 10 thousand
  years old.)
• Relative Age The age compared to the ages of
  other rocks. (older than this rock, younger than
  that rock.)

3
Age cont.

• Relative Age Much easier to figure out. Can be
  deduced from clues on the Earth.
• Absolute Age Much harder to figure out. Often
  impossible.

4
What are the ways to tell RELATIVE AGE.

• 1. Law of Superposition
• 2. Extrusion Intrusion
• 3. Faults
• 4. Unconformities

5
What is the Law of Superposition?

• In horizontal sedimentary rock layers, the
  oldest layer is at the bottom. Each higher layer
  is younger than the layers below it.

6
Age and Superposition