Thu Apr 18, 7:20 PM ET
By RANDOLPH E. SCHMID, Associated Press Writer
WASHINGTON (AP) - Two superplumes of molten rock appear to be powering through the boundary between the Earth's upper and lower mantle, perhaps feeding volcanoes and affecting movement of the planet's crust.
New evidence of the superplumes — located beneath the south central Pacific Ocean and southern Africa — comes from studies of seismic waves conducted by scientists at the University of California at Berkeley and reported in Friday's issue of the journal Science.
Smaller regions of magma rising to the Earth's crust power volcanoes and other hot spots.
But the superplumes come from far deeper, crossing the boundary between the upper and lower mantle about 400 miles deep, an area that had been thought by some scientists to impede the flow of material.
