ASBOG Practice Exam

What type of fold is described as a concave fold whose limbs close downward to the fold axis?

1. Antform

2. Synform

3. Anticline

4. Syncline

The correct answer is: Syncline

The fold described as a concave fold whose limbs close downward to the fold axis is known as a syncline. In geological terms, a syncline is characterized by the downward bending of rock layers, creating a trough-like structure. This formation occurs due to compressional forces that bend and buckle the Earth's crust, allowing the layers to dip inward toward the axis of the fold. In a syncline, the youngest rock layers are typically found at the core of the fold, which is the opposite of an anticline where the oldest layers are at the center and the limbs dip away from the fold axis. Understanding the positioning of rock layers in relation to the fold axis is crucial for identifying and interpreting geological structures. This knowledge is fundamental in fields such as geology and civil engineering, where understanding the behavior of Earth's materials is essential.