Question

As per Ramsay’s classification of folds, the maximum thickening of fold hinge and the maximum thinning of the fold limbs are observed in ____.

• A. Class 1A
• B. Class 1B
• C. Class 2
• D. Class 3

Answer 1

The Correct Option is D

To answer this question, we need to understand Ramsay’s classification of folds, which is a part of structural geology. Ramsay’s classification divides folds into three main classes based on the geometry and mechanical properties of the fold layers: Class 1, Class 2, and Class 3.

Each class is further divided into subclasses based on specific features:

• Class 1: Convergent Isogons, further subdivided into:
  • Class 1A: Shows maximum thickening at the hinge and thinning on the limbs. The profile resembles a chevron pattern.
  • Class 1B: Go through harmonic folds with uniform thickness conditions.
  • Class 1C: Also shows maximum thickening at the hinge but with different limb characteristics compared to 1A.
• Class 2: Parallel Isogons, where the fold limb thickness remains constant across its length, maintaining the layer thickness but not the same curvature.
• Class 3: Divergent Isogons, in which maximum thinning occurs at the fold limbs while the hinge is less affected. These folds are often described as exhibiting disharmonic or non-cylindrical properties.

Now, looking at the question, it specifically asks which class shows maximum thinning of the fold limbs. According to Ramsay’s classification, Class 3 folds exhibit divergent isogons that lead to maximum thinning at the limbs. Hence, the correct answer is Class 3.

Thus, the accurate answer to the question is:

Class 3.