If a fault line cuts through rock layers, the fault is ____ the layers.

If a fault line cuts through rock layers, the fault is ____ the layers.

• A. Younger
• B. Older
• C. Same age
• D. Not enough information

Answer: (A)

Cross-cutting relationships: a feature that cuts through rocks must be younger than the rocks it cuts. The rock layers had to exist and become solid before the fault could slice through them, so the faulting event happened after the layers formed. That’s why the fault is younger than the layers it displaces. The other ideas don’t fit because a fault that cuts through rocks can’t be older than those rocks, and saying the same age ignores the disruption caused by the fault.

Cross-cutting relationships: a feature that cuts through rocks must be younger than the rocks it cuts. The rock layers had to exist and become solid before the fault could slice through them, so the faulting event happened after the layers formed. That’s why the fault is younger than the layers it displaces. The other ideas don’t fit because a fault that cuts through rocks can’t be older than those rocks, and saying the same age ignores the disruption caused by the fault.