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Comment: 21:20 - 22:09 (00:49)
Source: Annenberg/CPB Resources - Earth Revealed - 6. Plate Dynamics
Keywords: plate, "plate tectonics", convection, mantle, rock, lithosphere, "mantle plume", atmosphere, "hot spot", volcano
Our transcription: In the late 1960s, it was suggested that there are places beneath the middle of the plates where a special kind of convection takes place.
Comparatively narrow columns of hot mantle rock rise from below and spread radially outward as they reach the lithosphere.
These are known as "mantle plumes."
This kind of circulation can be seen in other more familiar phenomena that occur in our atmosphere.
When thunderhead clouds form, for example, a similar type of plume convection is taking place but in an accelerated manner.
Evidence of mantle plumes has been found in the form of hot spots, regions of concentrated volcanic activity, which are roughly circular in shape.
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