1. Relative Dating Notes

2. Relative Age of Rocks
Relative Dating: Order rocks deposited tells you relative age of rocks (order from old to young)
Geologic Cross-Section Maps: show the structure of rocks underground.
Can determine the relative age of rocks by using 5 geologic principles:

3. Law of Superposition:
In sedimentary rock, the oldest layer is on bottom & youngest is on top.

4. Canyonlands, Utah

5. Law of Original Horizontality:
Sediments deposited in flat, horizontal layers. If rock layers are folded or at an angle, they were disturbed after originally deposited

6. Raplee Monocline, Utah

7. Unconformity:
Surface where a break in deposition of sediments occurred or period of erosion.

8. Eastern Grand Canyon

9. Law of Cross Cutting Relationships:
Fault lines or igneous rock intrusions are younger than the rock it cuts across.

10. Hance Rapids, Grand Canyon

11. Principle of Inclusion:
Rock material trapped inside igneous intrusion or sedimentary rock layer is older than rock that surrounds it.

12. Lake Pleasant