Question

In an outcrop we find that the bedding planes are vertical and cleavage surfaces are horizontal. Which of the following fold types is/are inferred from this observation?

• A. Upright fold
• B. Recumbent fold
• C. Vertical fold
• D. Neutral fold

Hint:

In structural geology, the relationship between bedding planes and cleavage surfaces is key to identifying fold types. Recumbent folds typically have horizontal axial planes and cleavage surfaces, while neutral folds have intermediate axial planes.

Answer 1

The Correct Option is B, D

Step 1: Understanding the question.
The question describes a situation where the bedding planes are vertical, and the cleavage surfaces are horizontal. We need to infer the type of fold this represents.
Step 2: Analyzing the options.
(A) Upright fold: This is unlikely — Upright folds typically have horizontal bedding planes. In this case, the bedding is vertical, so this is not the most suitable answer.
(B) Recumbent fold: Correct — Recumbent folds often have nearly horizontal axial planes and are characterized by horizontal cleavage surfaces. This fits the description provided.
(C) Vertical fold: This is incorrect — Vertical folds typically have vertical bedding planes, but the relationship between bedding and cleavage described here does not match the characteristics of a vertical fold.
(D) Neutral fold: Correct — Neutral folds are characterized by axial planes that are at an intermediate angle, and they could have the features described in the question.
Step 3: Conclusion.
The correct answer is (B), (D), as both recumbent and neutral folds are consistent with the observation of vertical bedding planes and horizontal cleavage surfaces.