The given outcrop pattern on a flat topography represents:
Show Hint
On a map, straight parallel fold traces usually mean horizontal folds. Elliptical or eye-shaped closures always mean a plunging fold. Look at limb dips to decide antiform (convex up) vs synform (concave up).
Step 1: Recall key fold geometry concepts.
- Antiform: A fold that is convex upwards (limbs dip away from the hinge). Whether it is an anticline or not depends on the facing direction of strata.
- Synform: A fold that is concave upwards (limbs dip towards the hinge).
- Horizontal fold: Fold axis is horizontal; map pattern is parallel bands, not closure.
- Plunging fold: Fold axis is inclined (plunging into the ground); map pattern forms closures (elliptical or eye-shaped patterns) on a horizontal surface.
- Axial culmination/depression: Refers to local highs or lows of the hinge line, not the closure itself.
Step 2: Interpret the figure.
- The map pattern shows elliptical eye-shaped closures, which indicate a plunging fold.
- The fold axis is clearly drawn and is inclined toward both ends (not horizontal).
- The convex-up shape with outward-dipping limbs indicates an antiform.
Step 3: Eliminate wrong options.
- (A) Antiform with axial culmination $\Rightarrow$ would not show elliptical closures but rather a culmination structure. Not correct.
- (B) Horizontal fold $\Rightarrow$ would give parallel stripes in outcrop, not an eye pattern. Not correct.
- (D) Synform with axial depression $\Rightarrow$ would be concave upwards, inconsistent with the given antiform geometry. Not correct.
Step 4: Correct interpretation.
Thus, the fold shown is an antiform with a plunging hinge line $\Rightarrow$ a plunging antiform.
Final Answer:
\[
\boxed{\text{Plunging antiform}}
\]
