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Plate Tectonics - Plates Colliding form Fold Mountains.

As shown on the previous page, when an oceanic plate collides
with a continental plate, the enormous forces cause rocks
to melt and new magma is formed. This magma under pressure
may burst out of a volcano as much as 100 km inland
from the plate boundary as shown in the picture below.

Fold Mountains and an Oceanic Trench

The continental plate is crumpled and folded,
giving rise to mountain ranges called fold mountains.
The Andes mountain range is formed in this way, on the
west coast of South America where the oceanic Nazca Plate
collides with the South American Plate which is continental.

What is a Subduction Zone?

An oceanic trench is formed offshore where the
oceanic plate is forced downwards at the subduction zone.

Subduction Zone

Two continental plates may also collide and build mountains.
An example is the Himalayas, where the
Indo-Australian Plate is colliding with the Eurasian Plate.
The Himalayas are the world's highest mountains.

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