Question

How are mid-ocean ridges and deep-ocean trenches related to plate tectonics?

Answer 1

Under-water trenches and ridges are created by plate tectonics.

Explanation:

The crust of the earth is covered with Oceanic and Continental plates. These plates are moving constantly but are moving very very slowly. They move because of something called convection currents. Convection currents push these plates together and apart. Convection currents are created by rising and falling heat in the earth's mantle.

When two oceanic plates are pushed away from each other, magma rises to the surface between the plates and creates a ridge.

Here are links to some websites you might like:

Convection Currents in the Earth's Mantle (Interactive)
Mountain Maker, Earth Shaker (Interactive)
Bitesize Geography