Mountains made of crumpled and folded layers of rock are called folded mountains.

Here's why:

* Folding: The intense pressure from tectonic plates colliding causes the rock layers to bend and fold, creating the characteristic ridges and valleys.

* Layers: These mountains are formed from sedimentary rocks, which were originally deposited in layers.

Some famous examples of folded mountains include:

* The Himalayas

* The Alps

* The Appalachian Mountains