Which type of stress causes rocks to fold? A. compression B. shearing C. strike-slip D. tension
The Correct Answer and Explanation is :
The correct answer is A. Compression.
Explanation
In geology, compression stress is responsible for causing rocks to fold. Folding happens when rocks are subjected to stress that pushes them together, usually as tectonic plates move toward each other. This force compacts the rock layers, causing them to bend and fold rather than break. This type of deformation occurs mainly in regions where tectonic plates converge, such as at continental collision zones, mountain ranges, or subduction zones. For example, the Himalayas were formed through immense compressive forces when the Indian and Eurasian plates collided, creating the folded mountain structures we see today.
Types of folds created by compression stress include anticlines and synclines. An anticline is an upward-arching fold, while a syncline is a downward-arching fold. These structures can form a variety of shapes depending on the angle and intensity of the compressive forces. When the forces are intense, rocks can form complex structures known as recumbent folds, where the layers are tilted horizontally, or overturned folds, where the rock layers can appear upside down.
Other types of stress affect rocks differently:
- Shearing (Answer B): This stress occurs when forces slide past each other horizontally, often resulting in fault lines rather than folds.
- Strike-slip (Answer C): Similar to shearing, this stress occurs horizontally and is associated with transform boundaries, like the San Andreas Fault.
- Tension (Answer D): This type of stress stretches rocks apart, causing fractures rather than folds, as seen in rift valleys.
Compression is unique in that it not only changes the rock’s shape but also creates distinct, wave-like patterns that contribute significantly to Earth’s geological formations.