1. FINDING RELATIVE AGE

2. What is relative age?  1. The age of a rock compared to the ages of other rocks.  Absolute age-the EXACT age of rock (add to your paper)

3. Finding Relative Age  2. Principle of Original Horizontality: States that layers of sedimentary rock are laid down horizontally (from left to right).

4. Finding Relative Age  3. Law of Superposition: In horizontal layers of sedimentary rock, the OLDEST is at the bottom. Each higher layer is YOUNGER than the layers below it.

5. D Youngest Layer (most recently formed) C B A Oldest Layer (at the bottom)

6. Finding Relative Age  4. Principle of Uniformitarianism: States that “History repeats itself.” What happened in the past will continue to happen in the same way. *This supports the Law of Superposition.

7. Clues to finding Relative Age  5. Extrusion: Always younger than the layers below it.

8. Clues to finding Relative Age  6. Intrusion: Always younger than the layers below it and the one it cuts through.

9. Clues to finding Relative Age  7. Fault (break in rock): Always younger than the rock it cuts through.

10. Clues to finding Relative Age  8. Unconformity (gap in the geologic record):  A. Deposition builds up rock layers.  B. Some layers erode away.  C. New rock layers form on top.  D. New rock meets much older rock.

11. /\/\/ = FAULT I = INTRUSION X = EXTRUSION G F /\/\/ E D IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII C IIIIIIIIIIIIIIIIIIIIIIIIIII B XXXXXXXXXXXXXXXXXXXXXXXIIIIIIIIIIIIIIIIIIIIIIIIIIIIXXXXXXXXXXXXXXXXXXXXXXXXXX A IIIIIIIIIIIIIIIIIIIIIIIIIIII