Question: I know that the tectonic plates move, but why do they move? :)

Sheona Masterton answered on 12 Nov 2015:

Excellent question Rosie! The tectonic plates sit on top of Earth’s mantle, which is made of molten, gloopy rock that moves very slowly over tens of thousands of years. This process is called mantle convection, and is driven by differences in temperature and chemistry of the mantle. As the mantle moves, it drags the tectonic plates along with it at the surface. If you imagine getting a big tub of golden syrup (to represent the mantle) and floating some biscuits on the top (to represent the plates) and heating it with a bunsen burner, that would show convection in action. Have a look on Youtube for ‘tectonic plate golden syrup’ experiments. Or even better, convince your teacher to let you do it in school!

It gets a bit more complicated at plate boundaries, where different tectonic plates meet each other, depending on if the two plates are colliding, moving apart, or sliding along next to each other. If the plates are colliding, then they’ll either crumple up into mountain ranges (like in the Himalayas) or one plate will be forced to sink down under the other to form something called a subduction zone (like the one near Japan). If the plates are moving apart then new ocean crust will form in between them as a mid-ocean ridge (like the one that Iceland sits on top of). Finally, if the plates are sliding along next to each other, you get something called a strike-slip fault (like the San Andreas Fault in California).