Earth: The Power of the Planet 1. Volcano (11 of 32)

Earth: The Power of the Planet

The water is just four degrees Celsius.
But it's worth it because I'm actually swimming in the gap between the two giant plates that run through Iceland.
To my left, the North American Plate and to my right, Europe.
These sheer rock faces were once joined together, but driven by immense geological forces, the land was split apart to create these deep chasms which filled with water.
It 's hard to imagine a force that can move continents apart, yet this is precisely what the Earth's inner heat is able to do.

It happens because hot rock rises, heated by the Earth's core.
Near the surface, the rock spreads in two directions and goes sideways.
It begins to lose heat.
Eventually, the much cooler rock sinks back down.
Through this spreading process, the Earth's crust is very slowly dragged apart, and it's this that ultimately causes the continents to move.
The lava lake at Erta Ale is an example of the same process but in miniature.
As we've seen, the movement of hot lava drags the crust across the surface of the lake, just as the continents are pulled across the Earth's surface.