Here's how it works:

* The Nazca Plate (oceanic) is subducting (diving) beneath the South American Plate (continental).

* As the denser oceanic plate descends, it melts due to friction and heat from the Earth's mantle.

* This molten rock rises to the surface, creating volcanoes and forming the Andes mountain range.

* The process also causes uplift and folding of the continental crust, further contributing to the mountain's height.

This type of plate boundary interaction is responsible for some of the Earth's most dramatic and geologically active features.