On the Move With Earth’s Continents and Ocean Floors

03 January 2011

An American soldier checks the wreckage inside the cathedral of Our Lady of Assumption in Port-au-Prince, Haiti on Tuesday Jan. 19, 2010,

FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus.

STEVE EMBER: And I'm Steve Ember. Scientists who study the Earth tell us that the continents and ocean floors are always moving. Sometimes this movement is violent and results in death and destruction. Today, we examine what causes earthquakes.

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FAITH LAPIDUS: The first pictures of Earth taken from space showed a solid ball covered by brown and green landmasses and blue-green oceans. It appeared as if the Earth had always looked that way -- and always would.

Scientists now know, however, that the surface of the Earth is not as permanent as had been thought. Scientists found that the surface of our planet is always in motion. Continents move about the Earth like huge ships at sea. They float on pieces of the Earth’s outer skin, or crust. New crust is created as melted rock pushes up from inside the planet. Old crust is destroyed as it moves toward the hot rock and melts again.

STEVE EMBER: In the twentieth century, scientists began to understand that the Earth is a great, living structure. Some experts say this new understanding is one of the most important revolutions in scientific thought. The revolution is based on the work of scientists who study the movement of the continents. This process is called plate tectonics.