Earth is Always on the Move
July 30, 2013
Jennifer Lopez performs at the Muhammad Ali Celebrity Fight Night Awards
From VOA Learning English, this is SCIENCE IN THE NEWS, in Special English. I’m Kelly Jean Kelly.
And I’m Christopher Cruise. Scientists who study the Earth tell us the continents and ocean floors are always moving. This movement sometimes can be violent, causing death and destruction. Today, we examine what causes earthquakes and volcanic activity.
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.
Yet the surface of the Earth is not as solid or 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, floating 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.
In the twentieth century, scientists began to understand that the Earth is a great, living -- and moving -- structure. Some experts say this understanding is one of the most important revolutions in scientific thought.
The knowledge of the Earth’s constant motion is based on the work of scientists who study the movement of the continents. This process is called plate tectonics.
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