2. Is the intrusion (layer D) older or younger than layer A? Why? (2 points)
To determine whether the intrusion (layer D) is older or younger than layer A, we need to analyze the principles of relative dating.
1. Principle of Superposition: This principle states that in an undisturbed sequence of rock layers, the youngest rocks are found at the top, and the oldest rocks are found at the bottom. Layer A is located below the intrusion (layer D), suggesting that layer A is older than the intrusion.
2. Principle of Cross-cutting Relationships: This principle states that any rock or fault that cuts across other rock layers is younger than the rocks it cuts across. The intrusion (layer D) cuts across layer A, indicating that the intrusion is younger than layer A.
Considering both principles, we can conclude that the intrusion (layer D) is younger than layer A.