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An introduction to geology
An introduction to geology

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1.10 What is plate tectonics? Continental drift and sea floor spreading - part 2

As you saw in the previous section, the stripes in the sea floor are caused because some of the rocks cooled at times when the magnetic field was reversed, and the stripes are symmetrical because as new rock is formed in the centre, it pushes the rest of the sea floor out of the way. This is shown in the video below (note: this video has no sound).

Download this video clip.Video player: Video 1.5 Magnetic reversal stripes
Video 1.5 Magnetic reversal stripes
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This is how the continents moved apart. New sea floor is created, which pushes the continents apart. This isn’t just happening in the middle of the Atlantic, but all over the world’s oceans, in areas called ‘mid-ocean ridges’.