Geography Edexcel paper 1 - Tectonics

Why do we have tectonic plates?

The earth’s surface is broken up into plates due to heat generated in the earth’s core by radioactive decay

What are the 3 main types of plate boundaries?

Destructive(convergent) - plates collide into each other

Constructive (Divergent) - plates moving away from each other

Conservative (transform) - plates slide past each other

Collision (This is another form of destructive boundary) - two continental plates move towards each other, crumpling and folding the land to form fold mountain ranges like the Himalayas.

What are convection currents?

the circular movements of semi-molten rock in the Earth's mantle, driven by differences in temperature

How do convection currents work?

Has convection currents been disproven?

Yes because:

• The heat generated from convection is not enough to pull the plates

• The slab pull theory suggest that the plates are pulled down through gravitational sliding

• But they are useful for explaining hot spot plumes

What is a hot spot plume?

stationary, upward currents of hot magma rising from deep within the Earth's mantle that create volcanoes on the surface.

How do hot spot plumes work?

-The tectonic plate above the plume is constantly moving, typically due to convection currents in the mantle.

-As the plate moves, the magma plume burns through weaker parts of the crust, creating a volcano.

-The new volcano is active, but as the plate moves, it is carried away from the plume. A new volcano forms over the hotspot, and the older one becomes dormant. This process repeats, creating a chain of volcanoes, like the Hawaiian Islands.

What are the key characteristics for a hot spot plume?

• Location: Hot spots are not at plate boundaries, unlike volcanoes that form at convergent or divergent plate margins.

• Activity: The volcano directly above the hot spot is active, while those that have moved off the plume are dormant

• Age: The further a volcano is from the hotspot, the older it is. (the volcanoes farther away are older because they formed earlier in the plate's history.)