* Principle of Cross-Cutting Relationships: In geology, this principle states that a geologic feature that cuts through another feature must be younger.
* Fault Formation: Faults are fractures in the Earth's crust where there has been movement. This movement happens after the rocks surrounding the fault have already formed.
* Visualizing the Process: Imagine a stack of three books representing the rock layers. If you cut through all three books with a knife (representing the fault), the knife cut (fault) is clearly younger than the books (rock layers).
Therefore, if a fault cuts through three rock layers, the fault must have formed after the rock layers were deposited, making it younger.
