Describe the landforms associated with destructive plate margins and explain their formation. (8 marks)

Destructive plate margins are those where two plates are moving towards one another. In cases where an oceanic plate and a continental plate converge, the denser oceanic plate will be forced beneath the continental plate, creating a Benioff subduction zone, and an ocean trench such as the Marianas Trench. As the silica-rich oceanic plate is turned to magma by the heat from the earth's core, it will cause volcanoes to form - a volcanic arc such as the Cascade Range, of composite volcanoes. These will only erupt sporadically, but the eruptions will be violent and involve ash and possibly pyroclastic flows. 

If two oceanic plates collide, they will cause an island arc of composite volcanoes, such as the Aleutian islands, whereas if two continental plates collide they will form an area of continental collision. This results in mountain ranges such as the Himalayas, which continue to grow as the plates converge.