CPG CPG Structural Geology & Tectonics 1 — Questions and Answers
Question 1: What term describes the angle of inclination of a rock layer measured from the horizontal plane?
- Dip angle (Correct answer)
- Strike angle
- Plunge angle
- Trend angle
Correct answer: Dip angle
Dip is the angle of inclination measured downward from horizontal, perpendicular to the strike direction.
Question 2: In structural geology, 'strike' refers to which of the following?
- The direction of maximum dip
- The compass direction of a horizontal line on a planar surface (Correct answer)
- The angle of inclination of a fault plane
- The depth to a geological contact
Correct answer: The compass direction of a horizontal line on a planar surface
Strike is the compass bearing of a horizontal line formed by the intersection of a planar feature with a horizontal surface.
Question 3: A syncline is a fold in which rock layers:
- Dip away from the fold axis
- Dip toward the fold axis (Correct answer)
- Are horizontal throughout
- Are vertical at the hinge
Correct answer: Dip toward the fold axis
In a syncline, the rock layers dip toward the fold axis, forming a trough-shaped structure with younger rocks in the core.
Question 4: Which fault type is characterized by primarily horizontal movement with little to no vertical component?
- Normal fault
- Reverse fault
- Strike-slip fault (Correct answer)
- Thrust fault
Correct answer: Strike-slip fault
Strike-slip faults involve lateral (horizontal) movement of one block past another along a near-vertical fault plane.
Question 5: In a compressional tectonic setting, which fault type is most likely to form?
- Normal fault
- Strike-slip fault
- Thrust/reverse fault (Correct answer)
- Listric normal fault
Correct answer: Thrust/reverse fault
Compressional stress causes shortening, which produces reverse and thrust faults where older rocks are pushed over younger rocks.
Question 6: The hanging wall of a fault is defined as:
- The block below the fault plane
- The block above the fault plane (Correct answer)
- The surface trace of the fault
- The zone of crushed fault material
Correct answer: The block above the fault plane
The hanging wall is the rock mass that overlies the fault plane, while the footwall lies beneath it.
CPG CPG Structural Geology & Tectonics 1
What term describes the angle of inclination of a rock layer measured from the horizontal plane?