How fast do whole continents move?

Put your hand flat on the floor and feel how still it is. The ground under your home seems to stay in one place all day. Yet that ground is on the move right now, as you listen.

Every continent on Earth is travelling too. So let's wonder together: how fast do whole continents move?

Earth wears a hard outer shell of rock, and that shell is cracked into giant pieces. We call them plates, which means huge slabs of rock that fit together like a jigsaw puzzle. Each continent rides along on top of a plate.

Deep under the plates, the rock is so hot that it turns soft, like thick warm toffee. That soft rock can slowly bend and flow, so the plates resting on top of it can slide along.

Something has to pull the plates along. Where two plates meet, the old, cold edge of one plate is heavy, so it sinks down into the hot rock. As it sinks, it drags the rest of the plate behind it, like a blanket slipping off the end of a bed.

The soft rock underneath is thick and sticky, so the plates can only creep. They move so slowly that nobody on Earth can feel it. Can you guess what on your own body grows at about the same speed as a plate moves?

Your fingernails! The plates under the continents creep about as fast as your fingernails grow. In one whole year, a plate travels about the length of a paper clip.

That tiny distance adds up. By the time you are as old as a grandparent, your continent will have slid about as far as a bed is long, and a little more.

Over millions and millions of years, the plates on each side of the Atlantic Ocean crept apart, about one paper clip each year. That is how a whole wide ocean opened up between North America and Europe.

The heavy, cold edges of the plates sink into the hot, soft rock and drag whole continents along. Because that soft rock is thick and sticky, the continents only creep, about as fast as your fingernails grow, a paper clip's length each year.

Right now, deep under your feet, your plate keeps creeping along. Slow and steady as a growing fingernail, it carries your home with it.