3 types of plate margin:
Destructive margins: 2 plates moving towards each other. Oceanic meets Continental - denser oceanic plate SUBDUCTS under continental plate -> ocean trenches and volcanoes.
Continental meets continental -> smash together - no crust destroyed.
Constructive margins: 2 plates moving away from each other. Magma rises from mantle, fills gap and cools -> new crust.
Conservative margins: 2 plates moving sideways past each other. Crust NOT created OR destroyed
Fold mountains are formed at Destructive Margins
When tectonic plates collide: sedimentary rocks fold and are forced upwards -> mountains.
Fold mountains can form where continental plate collides with oceanic plate. EG Andes in South America.
Can also form where two continental plates collide. EG Himalayas in Asia.
Characteristics: Very high mountains, very rocky with steep slopes. Often snow and glaciers in highest parts, and lakes in valleys between mountains.