That's almost right! When tectonic plates collide, mountains are formed. Here's why:

* Tectonic Plates: The Earth's outer layer is broken into massive pieces called tectonic plates. These plates constantly move, albeit very slowly.

* Collision: When two tectonic plates collide, the denser plate often slides beneath the lighter plate in a process called subduction.

* Mountain Formation: As the plates collide, the land on the lighter plate is pushed upwards and crumpled, creating mountains.

Here's a breakdown of the types of collisions that create mountains:

* Continental-Continental Collisions: When two continents collide, they have similar densities, so neither one easily subducts. This results in intense folding and uplift, forming massive mountain ranges like the Himalayas.

* Oceanic-Continental Collisions: When an oceanic plate collides with a continental plate, the denser oceanic plate subducts beneath the continental plate. This process creates volcanoes and mountain ranges along the edge of the continent.

Let me know if you have any other questions!