Question

the diagram shows cross - cutting relationships among rocks
which statement accurately describes the geologic features?
d occurred after b.
d occurred before a.
a formed after the horizontal layer above was deposited.
f formed before the horizontal layer above was deposited.

Explanation:

Step1: Apply cross - cutting relationships principle

In geology, a cross - cutting feature is younger than the feature it cuts.

Step2: Analyze each option

• For “D occurred after B”: Since D (a fault or intrusion) cuts through B (a rock layer), by the cross - cutting principle, D is younger than B.
• For “D occurred before A”: If D cuts through A, then D is younger than A. But if there is no clear cross - cutting in the wrong way (assuming normal cross - cutting as in the principle), this option is wrong.
• For “A formed after the horizontal layer above was deposited”: If A is cut by the horizontal layer (unlikely as per cross - cutting where the cutting feature is younger), this is wrong. Usually, the overlying layer is younger in normal deposition (superposition principle), but if A is intruded, the intrusive rock (A) would be younger than the layers it intrudes, not the overlying ones.
• For “F formed before the horizontal layer above was deposited”: If F is cut by the horizontal layer (by cross - cutting, the horizontal layer would be younger), but if F is a pre - existing rock and the horizontal layer is deposited on top (superposition), F is older. But the cross - cutting (if any) is not in favor of this option as per the general cross - cutting and superposition understanding for the given problem.

So, the correct statement is “D occurred after B” as D cuts through B.

Answer:

D occurred after B.