This is a drawing of how a hot spot under the crust builds land on the surface.
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Image copyright 1997 by the American Geophysical Union. Further electronic distribution is not allowed.

Plume Volcanism

This drawing shows another way that islands are made. A rising hot bubble of material finds it's way into the crust of the Earth from the deep interior, and begins to erupt. This bubble or "plume" is called a "hot spot". Lava from the eruption turns to layers of rock and builds a volcanic "cone". Continual eruptions eventually build a whole island on the surface, with a volcano in the middle.

A similar process built the Tharsis Ridge of Marsand many volcanic rises on Venus. The volcanoes of Mars which were built this way became *very* large.


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