FORMATION OF FOLD MOUNTAINS Fold mountains are large mountain ranges formed mainly by the bending and folding of the Earth’s crust due to compressional forces. These forces occur when two tectonic plates collide or move toward each other. PROCESS OF FORMATION 1. PLATE COLLISION: Fold mountains usually form at convergent plate boundaries, where two continental plates (or sometimes an oceanic and a continental plate) collide. The immense pressure causes the crustal rocks at the edges of the plates