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Our transcription: When you just look at the topography of the general sea floor, every now and then you find a seamount. There'll just be little round cones. They range from real small to huge. Hawaii is one. We don't know about all of them, but a lot of them seem to be related to hot spots. Hot spot volcanism happens when there's a place way down in the mantle that for some reason produced extra lava, so much extra that it bubbles right up right through the plate and builds a seamount on top. Often it builds an island like Hawaii and the whole chain of islands that's strung along behind Hawaii. The reason they're interesting is that the hot spots seem to be still or nearly still down in the mantle, and so when the plate moves over it, it keeps making new volcanoes in a line, so that right now the Big Island of Hawaii is being built. The islands up the chain get older and older and there's, in fact, a chain that stretches way across the sea floor all the way up to The Aleutians, which are older and older, showing us the motion of the Pacific plate over that Hawaiian hot spot.
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