Final answer:
Intense deformation during mountain building is typically caused by the collision and movement of tectonic plates, resulting in folded and uplifted terrains. Erosive forces like water and ice further shape the mountains, which contrasts with smoother terrains on celestial bodies without such processes.
Step-by-step explanation:
Intense deformation during mountain building is primarily caused by the movement of tectonic plates.
When two continental plates collide, the force generated by this immense pressure can crumple, fold, and uplift the Earth's crust, forming mountain ranges.
The Alps serve as a classic example of this process, with the African and Eurasian plates pushing against each other.
Once a mountain range is created, it is exposed to external geologic processes like erosion by water and ice, which sculpt the terrain further, creating sharp peaks and dramatic landscapes.
For instance, in environments devoid of movement by ice or water, such as the Moon or Mercury, mountains remain with a smoother appearance, lacking the serrated edges and peaks seen on Earth.