Structural Geology MCQ with answer and solution

Concept

A dip fault has its strike parallel to the dip direction of the rock beds.

Step-by-step solution

1. Faults are classified by how the fault strike relates to the strike or dip of the beds. 2. Strike fault: fault strike is parallel to the strike of the beds. 3. Dip fault: fault strike is parallel to the dip direction of the beds. 4. Oblique (diagonal) fault: fault strike is at an angle to both. 5. So a dip fault is parallel to the dip of the beds. Answer is (A).

Explanation

In a dip fault, the fault line runs along the dip direction of the beds. It cuts across the strike of the beds at about 90°. So option (A) is correct.

Why the other options are wrong

(B) Parallel to strike describes a strike fault. (C) Diagonal to dip and strike describes an oblique (diagonal) fault. (D) Faults are classified by their relation to bedding, so 'no relationship' is wrong.

Shortcut

The fault name tells you what it is parallel to: dip fault is parallel to dip, strike fault is parallel to strike.

Common mistake

Confusing a dip fault (classified by orientation) with a dip-slip fault (classified by movement).