The theory that vent are driven by mantel plume — minute jets of magma arise within the Earth ’s inwardness — is a staple of geology . aim geologists , like everyone else , see in high school that vent far from home base boundaries rest above such plume . Subsequent education build on this like level of strata . So when the possibility is gainsay , a airfield of science quakes .
" Mantle plume have never had a sound physical or legitimate basis , " says Caltech ’s Professor Don Anderson . " They are akin to Rudyard Kipling ’s ' Just So narration ' about how camelopard incur their prospicient necks . "
While no one is sure on the button how mantle plumes flesh , the theory baffle as a way to explain chain of current and former volcanoes .
Los688 . Standard view of how vent chain of mountains take shape as tectonic plates drift over cape plume .
" Much of solid - ground science for the past 20 years — and large amounts of money — have been spend looking for elusive narrow mantle plumes that wind their way upward through the mantle , " says Anderson . While these efforts were abortive , their failure were explained as a result of the jets being too thin to show up on the devices trying to find them .
However , Anderson deal what he considers a death blow to the mantle plume theory in theProceedings of the National Academy of Sciences . He explore the Yellowstone , Hawaii and Samoa volcanic provinces with legion closely packed measuring devices and still found no grounds for narrow-minded jets in the mantle .
Instead , Anderson concludes , “ Convection in an isolated planet is characterize by narrow downwellings and broad updrafts — consequences of Archimedes ’ principle , the cooling required by the second law of thermodynamics , and the effect of compression on material properties . ”
What cause volcano then ? Anderson says they are “ the result of normal large-minded - scale convection and plate tectonics . ”
Lava lamps operate a lot like the traditional view of the Earth ’s magma . The bottom gets raging enough to drive jet of warm cloth to the top , where matter slowly chill and fall in blanket downdraft . However , lamp have an external DOE source . Earth ’s core warms via radioactive decay , but Anderson notes that — from a geological point of aspect — the planet is tardily cooling .
Surface cooling , along with plate tectonic movement , produces narrow channels of sinking material called slabs . These slab displace the lighter magma as they fall , stimulate broad plume one thousand of kilometres across to heighten until they hit the plate bottoms .
Where a crustal plate is cracked , the magma contract up through the scissure to surface as a vent . In Anderson ’s view , the narrow vent the volcano sits upon is a few hundred kilometres bass , not several thousand as opine in textbooks .
The example is similar to that proposed by Lord Kelvin in the 19th century . However , while Kelvin isreveredfor his work on thermodynamics , his vision of a cool planetignored radioactivity and operated on a scale leaf orders of order of magnitude faster than what we now know to be true , causing it to be disgarded .
