|MadSci Network: Earth Sciences|
I think you are talking about "hot-spots", that are "small" conducts, with a few hundred kilometers in diameter, that connect the core-mantle boundary with the surface. This idea was initially proposed by J.T. Wilson, of Toronto University, and the concept was developed later by W.J. Morgan, of Princeton, in 1970. Tuzo's idea was the only mechanism able to explain the volcanic island chains in regions where you don't have a lithospheric plate boundary (e.g., Hawaii Islands). The hot spots are the expression in the surface of these volcanic conducts, called "plumes". There are about 20 hot spots in the world, most of them in Africa, and one in the region of the Yellowstone Natl. Park. In these regions, one expect a high heat flow (with volcanism, geisers, etc.), and lava eruption if it is in the continent; if the hotspot is located in the oceanic area, as the lithospheric plate is moving, it can create chains of islands, just like Hawaii. In these island chains one can observe that in one end the volcanism is extinct and the island is older than the other extreme, where the volcanism is active and the island is young. An interesting reference about this theme can be found in chapter 16 ("Causes of Plate Tectonics") of the book "The way the Earth Works: an introduction to the new global geology and its revolutionary development", by Peter J. Wyllie, edited by John Wiley & Sons, Inc., 1976. Best regards Eder C. Molina firstname.lastname@example.org Dept. of Geophysics Institute of Astronomy and Geophysics University of Sao Paulo - BRAZIL
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