How are mountains formed? Mountains form through geological processes involving Earth's lithosphere (outer layer). *Process:* 1. *Plate Tectonics:* Continental plates collide, pull apart or slide past each other. 2. *Volcanic Activity:* Volcanic eruptions create volcanic arcs and mountain ranges. 3. *Folding and Faulting:* Earth's crust bends (folding) or breaks (faulting), lifting terrain. 4. *Weathering and Erosion:* Water, wind and ice shape mountains over millions of years. *Types of Mountai