Have There Always Been Continents?

South America and Africa look like two pieces of a jigsaw puzzle that fit almost perfectly, and there is a reason.

Although there are officially seven continents spread out over Earth, it wasn't always that way. Many scientists figure Earth began as one huge continent—dry as a bone. Water was delivered in comets, the thinking goes, and the oceans developed.

Much more recently, all the world's landmasses were huddled into one supercontinent called Pangaea, which means "all lands." It began to break up about 225 million years ago, eventually fragmenting into the continents as we know them today.

So are the continents still on the move? Yes. The continents are drifting apart at the rate of about an inch each year. The movement, and all the bumping and grinding it causes, create earthquakes, fuel volcanoes, and build mountains.

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