ASBOG Practice Exam

What occurs to the dip as one moves away from the fold axis line?

1. Decreases laterally

2. Increases laterally

3. Remains constant

4. Fluctuates randomly

The correct answer is: Increases laterally

As one moves away from the fold axis in a folded geological structure, the dip typically increases laterally. This phenomenon can be explained by the mechanics of folding. In a fold, especially in an anticline or syncline, the layers of rock are bent. When examining the orientation of the rock layers relative to the fold axis, the steepness, or dip, often becomes more pronounced as you approach the flanks of the fold. In an anticline, for example, layers are arched upwards, and the beds that are closer to the fold axis are generally at a lower angle. As you move laterally towards the edges of the anticline, the beds tilt steeper, which results in an increase in dip. A similar situation occurs in synclines, though with the orientation of the beds reversed. Understanding this trend is essential for geological mapping and for predicting the behavior of strata, which is crucial in fields such as natural resource exploration, civil engineering, and environmental studies.