Plate Tectonics

Question 1

What is the Plate Tectonic theory?

Answer 1

states the earth’s crust is made up of several plates that move relative to each other called continental drift – e.g. seashells at the top of Everest

Question 2

What are the key parts to the earths structure?

Answer 2

• The core – centre
• The mantle – the thickest part and the outer mantle is called the asthenosphere
• Outer layer = crust of which there are 2 types: the less dense but older continental crust and the younger but more dense oceanic crust (sinks under at a convergent plate boundary)

Question 3

Explain Constructive / divergent plate boundaries

Answer 3

• Plates are moving away from each other creating new crust using convection currents (hot air that rises and falls due to gravity systems)

Question 4

Destructive / Convergent Plate boundaries?

Answer 4

When the 2 types of crust meet the denser oceanic crust begins to sink under the continental crust due to subduction, this forms ocean trenches like the Marina Trench but also forms Young Fold Mountain due to sediment on the continental crust being deposited

Question 5

Convergent / Collision plate boundaries?

Answer 5

When 2 continental boundaries converge neither subduct as they are same density – causing them to collide forming mountains like the Himalayas

Question 6

Conservative Plate boundaries?

Answer 6

When 2 plates slide across each other, if they get stuck any sudden movements can cause earthquakes like along the San Adreas fault in California

Question 7

Hotspots?

Answer 7

• used to explain volcanic activity away from plate boundaries
• A hotspot beneath the crust stays stationary and breaks through the crust to form volcanos (islands) – due to plate movement the land above moves, and a new island begins to form creating a chain of islands – like seen with the formation of Hawaii