How are mountains formed.

Mountains are formed by slow but gigantic movements of the earth's crust

When sediments deposited on a seabed are subjected to compression, they are gradually squeezed and folded, after which they form huge chains of mountains called fold mountains. Sometimes, because of compressional forces the, horizontal layers of rocks break down into several pieces called blocks.

Explanation:

In short

The world's tallest mountain ranges form when pieces of Earth's crust—called plates—smash against each other in a process called plate tectonics, and buckle up like the hood of a car in a head-on collision.