Other margins

Question 1

Destructive Oceanic to Oceanic

Answer 1

• heavier plate subducts, leaving an ocean trench
• fold mountains occur
• Built-up pressure causes underwater volcanoes to bust through oceanic plate
• lava cools, forms new land called volc island arcs
• aleutian islands alaska, marianas islands SE of japan

Question 1

Destructive Continental on Continental

Answer 1

• both plates not as dense as oceanic so lots of pressure builds
• ancient oceanic crust subducted slightly, but no subduction of continental crust
• pile-up of continental crust on top of lithosphere due to pressure between plates
• fold mountains formed from plies of continental crust

Question 2

Constructive Continental to Continental

Answer 2

• any land in the middle of the separation is forced apart, forming a rift valley
• volcanoes form where the magma rises
• eventually, gap will fill with water and separate from main island
• lifted areas of rocks known as horsts, valley itself known as a graben

Question 3

Conservative plate

Answer 3

• paralell plates move in diff directions / diff speeds
• no plates destroyed so no landforms
• when they move, lots pressure built up = eq
• on oceanic crust, can displace a lot of water. - on continental crust, fault lines can occur where the ground is cracked by the movement