Doubly Plunging Folds and Elliptical Outcrops
Elliptical outcrop patterns on a level surface are most commonly exhibited by doubly plunging folds.
Understanding Doubly Plunging Folds
- A doubly plunging fold is a fold where the fold axis plunges (dips) towards both ends of the fold from a central high point (in an anticlinal structure) or low point (in a synclinal structure).
- Imagine a wave shape that dips downwards towards both its left and right ends.
Reason for Elliptical Outcrops
- When a doubly plunging fold intersects a horizontal (level) geological surface, the outcrop pattern often forms a closed elliptical shape.
- The closure happens because the rock layers defining the fold plunge away in opposite directions from the center, eventually returning to or below the level surface.
- The outcrop shape reflects the geometry of the fold axis and the intersection with the horizontal ground.
Comparison with Other Fold Types
- Plunging Antiforms/Synforms: These folds plunge in only one direction. Their outcrop pattern typically narrows and terminates at one end, rather than forming a closed ellipse on a level surface.
- Non-plunging Folds: These have horizontal fold axes. They usually produce linear outcrop patterns parallel to the axis or V-shaped patterns if they are eroded through, not typically elliptical shapes on a flat surface.
Therefore, the characteristic elliptical outcrop on a level surface points towards a doubly plunging fold structure.
Similar Questions
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Important Questions from Mixed Topic (CUET PG)
- Kalpsutra, the illustrated canonical text is from:-
- The Harappan city almost exclusively devoted to craft production was-:
- Mohandas Karamchand Gandhi launched quit India movement after the failure of:-
- The "Objectives Resolution" was introduced in constituent assembly by:-
- Who among the following was not a member of the constituent assembly:-
