Hope no one’s career tanked opposing it. From Phys.org:
In the typical textbook picture, volcanoes, such as those that are forming the Hawaiian islands, erupt when magma gushes out as narrow jets from deep inside Earth. But that picture is wrong, according to a new study from researchers at Caltech and the University of Miami in Florida.
New seismology data are now confirming that such narrow jets don’t actually exist, says Don Anderson, the Eleanor and John R. McMillian Professor of Geophysics, Emeritus, at Caltech. In fact, he adds, basic physics doesn’t support the presence of these jets, called mantle plumes, and the new results corroborate those fundamental ideas.
“Mantle plumes have never had a sound physical or logical basis,” Anderson says. “They are akin to Rudyard Kipling’s ‘Just So Stories’ about how giraffes got their long necks.”
Goodness! What big theory in biology does the giraffe’s neck remind us of?*
But now, thanks in part to more seismic stations spaced closer together and improved theory, analysis of the planet’s seismology is good enough to confirm that there are no narrow mantle plumes, Anderson and Natland say. Instead, data reveal that there are large, slow, upward-moving chunks of mantle a thousand kilometers wide.
“What’s new is incredibly simple: upwellings in the mantle are thousands of kilometers across,” Anderson says. The formation of volcanoes then follows from plate tectonics—the theory of how Earth’s plates move and behave. Magma, which is less dense than the surrounding mantle, rises until it reaches the bottom of the plates or fissures that run through them. Stresses in the plates, cracks, and other tectonic forces can squeeze the magma out, like how water is squeezed out of a sponge. That magma then erupts out of the surface as volcanoes. The magma comes from within the upper 200 kilometers of the mantle and not thousands of kilometers deep, as the mantle-plume theory suggests.
Here’s the significance:
Lord Kelvin’s name is associated with the laws of thermodynamics and the cooling Earth hypothesis. The widely accepted mantle plume conjecture has been justified by experiments and calculations that violate the laws of thermodynamics for an isolated cooling planet. Hotspots such as Hawaii, Samoa, Iceland, and Yellowstone are due to a thermal bump in the shallow mantle, a consequence of the cooling of the Earth. They are not due to ~100- to 200-km-wide tubes extending upward from fixed points near the Earth’s core. Seismic imaging shows that features associated with hotspots are thousands of kilometers across, and inferred ascent rates are low. Plate tectonic-induced updrafts and a cooling planet explain hotspots and the volcanoes at oceanic ridges. (Abstract follows; public access)
Follow UD News at Twitter!
*Remember, Darwinism is not evolution. It is a theory of a mechanism for evolution. Natural selection is objectified as a force that creates complex, specified information from random mutations. That is the Darwinian creed. It’s false, but a vast academic science industry now depends on it (Besides, it is easy for TV presenters to teach.)