Question

A horizontal upright fold will have a

• A. vertical fold axis and horizontal axial plane
• B. horizontal fold axis and vertical axial plane
• C. horizontal fold axis and axial plane with any dip
• D. plunging fold axis on a vertical axial plane

Answer 1

The Correct Option is B

To solve this question, we need to understand the concepts of fold axes and axial planes in geology, specifically related to a horizontal upright fold.

Key Concepts

Fold Axis: This is an imaginary line that, when moved parallel to itself, generates a fold surface. The orientation of the fold axis is crucial in determining the type of fold.

Axial Plane: This is an imaginary plane that divides a fold as symmetrically as possible. It contains the trace of the fold axis and divides the fold into two limbs.

Understanding Fold Types

A horizontal upright fold has specific characteristics:

It features a horizontal fold axis, meaning the fold axis is parallel to the Earth's surface.

The axial plane is vertical, which means it is perpendicular to the horizon.

Analysis of Options

Option 1: "Vertical fold axis and horizontal axial plane" - This does not describe a horizontal upright fold as it features a vertical fold axis.

Option 2: "Horizontal fold axis and vertical axial plane" - This correctly describes a horizontal upright fold.

Option 3: "Horizontal fold axis and axial plane with any dip" - While the fold axis is correctly described, the axial plane is specified as 'any dip,' which is incorrect for the upright fold characterized by a vertical axial plane.

Option 4: "Plunging fold axis on a vertical axial plane" - This describes a plunging fold, not a horizontal upright fold.

Conclusion

The correct answer is Option 2: "Horizontal fold axis and vertical axial plane," as it accurately describes the characteristics of a horizontal upright fold.