Final answer:
A fault trace curve that compresses two sides together is known as a reverse fault or a thrust fault if the dip is shallow. These faults are associated with compressional stress and can lead to mountain building.
Step-by-step explanation:
When the fault trace curves and movement along the fault compresses the two sides together, it is known as a reverse fault or, if the angle of the dip of the fault plane is shallow (less than 30°), a thrust fault. In these types of faults, the hanging wall moves upwards relative to the footwall. This motion is typically associated with compressional stress and can lead to the formation of mountain ranges or uplifted areas.
Thrust faults are significant in the context of mountain building and are often found in regions where tectonic plates collide, forming folded and uplifted geological structures such as anticlines and synclines. These compressional features are important for understanding the geology of an area, particularly for the identification of potential areas where resources like petroleum or minerals may be concentrated.
A classic example is the Copper Creek Thrust Fault in Tennessee, associated with the Appalachian Mountains, a result of the tectonic collision between the continental plates of Africa and North America during the Pennsylvanian period. The fault zones revealed by these structures illustrate the dynamic nature of Earth's crust.