Horizontal movements take place because of compressional or tensional forces. They are responsible for the formation of fold mountains. When compressional forces act from two opposite directions, the rocks on the crust of the Earth bend and form arches, troughs, or mountains. This is known as the folding of crustal rocks. Anticline is the arch or the upward fold, while syncline is the downward fold.
Sometimes, when the crustal rocks are subjected to horizontal compressional pressure, they do not get folded. Instead, they develop fractures or cracks along the line of weakness. These lines of fracture are known as faults. The movement of the part of the Earth’s crust along the line or fault is known as faulting. Block mountains are formed because of faulting.
Also, Read Folding and Faulting