Plate Tectonics- Plate Movements 😊

Question 1

Why do plates move? X2

Answer 1

1. Convection currents- heat is emitted from radioactive decay in the core that causes convection currents in the mantle. The sinking and rising of heat pulls the plates down.
2. Slab pull- movement of a plate downwards due to gravity and convection currents. Some plates move at a faster rate than others as they have different densities.

Question 2

What happens at divergent plate boundaries?

Answer 2

Plates move apart

Question 3

What happens at constructive boundaries?

Answer 3

Plates move together

Question 4

What happens at constructive boundaries?

Answer 4

Plates slide past each other either in the same or opposite direction to each other

Question 5

How are ocean ridges formed? Divergent X4 steps

Answer 5

• plates move apart
• magma rises up to fill in the space between the plates
• a central rift is formed
• transform faults are also formed which are parallel to one another and move at different speeds

Question 6

How was rift valleys formed?

Divergent X4 steps

Answer 6

• plates move apart
• heat causes the land to dome
• this then causes the land to sink in the middle due to pressure forming a Rift Valley
• faults run parallel and the land may eventually be covered by the ocean

Question 7

Oceanic- continental plates

Convergent X5 steps

Answer 7

• plates move together (convection currents and slab pull)
• denser oceanic subducts under continental
• an accretionary wedge is formed which water may enter
• by the Wadati-Benioff zone the plate melts forming basaltic lava that turns andesitic
• locked faults occur and this can result in megathrust earthquakes

Question 8

Oceanic- oceanic plates

Convergent X5 steps

Answer 8

• plates move together (convection currents and slab pull)
• denser of the two plates subducts so a Wadati-Benioff zone is formed
• may get locked faults which result in megathrust earthquakes
• magma from the melting of the plate rises to the zone to form an arc of submarine volcanoes
• these may build up above sea level to eventually form curved island arcs

Question 9

Continental- continental

Convergent X5 steps

Answer 9

• plates move together to form a collision boundary
• some subduction may occur
• rock is forced and folded upwards to create fold mountains
• some of the continental lithosphere is forced into the asthenosphere
• mountain roots are created

Question 10

What happens at a conservative boundary?

Answer 10

• no plate is created or destroyed
• no volcanic activity or formation of new lithosphere
• locked faults may occur which may result in seismic activity
• perpendicular transform faults are formed