1. The granite is the oldest rock layer because it is an igneous intrusion that cuts across all other layers, indicating it formed after they were deposited but before any overlying layers were added.
2. The schist is older than the sandstone Y because the sandstone Y is deposited on top of the schist, following the Law of Superposition.
3. The conglomerate is younger than the shale because it lies above the shale layer.
4. The siltstone Q is older than the sandstone X because the sandstone X is deposited on top of the siltstone Q.
5. The limestone is the youngest rock layer shown in the diagram because it is the topmost layer in the sequence.
Parent Tip: Review the logic above to help your child master the concept of geologic column worksheet.