1. Relative Dating

2. Identifying which rock units formed first, second, third, and so on. Tells us the sequence in which events occurred, not how long ago they occurred Relative Dating

4. Law of Superposition If undisturbed, the layer above is younger and the layer below is older.

8. Principal of Original Horizontality Layers are deposited in a horizontal position Any movement happened after the layer was formed

11. Principle of Cross-cutting Relationships When something cuts through another layer, it is younger then everything it cuts through.

14. Inclusions If pieces of one layer are contained in another layer, the layer with the pieces is younger.

16. Unconformities Erosion removes previously formed layers, and then is covered by new layers.