Presentation on theme: "FINDING RELATIVE AGE. 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."— Presentation transcript:
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)
Finding Relative Age 2. Principle of Original Horizontality: States that layers of sedimentary rock are laid down horizontally (from left to right).
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.
D Youngest Layer (most recently formed) C B A Oldest Layer (at the bottom)
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.
Clues to finding Relative Age 5. Extrusion: Always younger than the layers below it.
Clues to finding Relative Age 6. Intrusion: Always younger than the layers below it and the one it cuts through.
Clues to finding Relative Age 7. Fault (break in rock): Always younger than the rock it cuts through.
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.
/\/\/ = FAULT I = INTRUSION X = EXTRUSION G F /\/\/ E D IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII C IIIIIIIIIIIIIIIIIIIIIIIIIII B XXXXXXXXXXXXXXXXXXXXXXXIIIIIIIIIIIIIIIIIIIIIIIIIIIIXXXXXXXXXXXXXXXXXXXXXXXXXX A IIIIIIIIIIIIIIIIIIIIIIIIIIII