Plate Tectonics

Yr 10 Science

Oceanic more of less dense?

More dense

Continental more of less dense

Less dense

Oceanic type of rock

Basalt

Continental type of rock

Granite

Oceanic found where

The bottom

Continental found where

On top of oceanic plate

Oceanic thinner or thicker

thinner

Continental thinner or thicker

Thicker

Oceanic is

continually being made or destroyed

Continental

stays the same for long periods of time

What are some factors that both oceanic and continental have?

Found in the same layer (crust), lithosphere, made out of rock, involved in tectonic activity.

What did Alfred Wegener think and discover?

Continental outlines matched, similar fossils found on different continents/ rock types matched each other, coal found in cold areas + evidence of glaciers found in the tropics.

Why did the other scientists not believe Wegener?

He couldn’t prove how they moved, so scientists couldn’t understand why it happened.

Mid ocean ridge- converging or diverging

Diverging

Subduction zone- converging or diverging

Converging

Collision zone- converging or diverging

Converging

Mid ocean ridge making or destroying plates

Making oceanic

Subduction zone making or destroying plates

Destroying

Collision zone making or destroying plates

Neither

Mid ocean ridge type of plate

Oceanic

Subduction zone type of plate

Both plates

Collision zone types of plates

Continental

Mid ocean ridge evidence for this kind of plate interaction and example of where it occurs in the world.

Young rock- middle of ocean ridge, older rock- further away + Iceland

Subduction zone evidence for this kind of plate interaction and example of where it occurs in the world.

Volcanoes + Pacific ring of fire

Sliding edges evidence for this kind of plate interaction and example of where it occurs in the world.

Earthquakes- San Andreas Fault

Collision zone evidence for this kind of plate interaction and example of where it occurs in the world.

Mountain growing (Mt Everest) + Himalayas

What is a mid ocean ridge

When 2 oceanic plates seperate

What is a subduction zone

Oceanic plate subducts under continental because it is more dense.

What is a sliding edge

Plates moving in parallel and opposite directions. Force builds up in the form of friction, which stops the plates from moving.

What is a collision zone

No subduction occurs. The continental plates are forced upwards and form mountains.

Reasons for tectonic plate movement: Convection currents

Hot magma rises because it becomes less dense, and then cool magma sinks because it becomes less dense. At the top of each cycle, the sideways movement of cooling rock in the mantle cause the movement of tectonic plates above it.

Reasons for tectonic plate movement: Gravity

Gravitational forces cause older materials on the peaks and ridges to sink towards the ocean floor, aiding the movement of the plates because the sinking dense crust drags the rest of the tectonic plate downwards. This is the main cause of plate motion.