Final answer:
Folded mountains are formed when crusts collide and push upwards, as seen in the formation of the Alps due to the collision of the African and Eurasian plates.
Step-by-step explanation:
When crusts collide and push upwards, a type of mountain called folded mountains is typically formed.
This geological process occurs as the Earth's crust buckles and folds due to the immense pressure of colliding continental masses, similar to what formed the Alps, when the African plate bumped into the Eurasian plate.
These mountain ranges can reach impressive heights of several kilometers, a result of the tectonic forces at work.