Current research suggests that mantle plumes
originate some 1,800 miles beneath the earth’s
surface, where the liquid-metal outer core meets
the lowermost part of the rocky mantle. Seismic
experiments indicate that the core is not smoothly
spherical but has many irregularities, perhaps
analogous to the mountain ranges on the earth’s
surface. It could be that these core irregularities
direct heat flows to produce rising plumes of
molten rock capable of penetrating the thick mantle
and even reaching the earth’s surface.
There is evidence to suggest that mantle plumes
have been responsible for, or have played a major
role in, the breaking-up of supercontinents such
as Pangea and Gondwanaland. Some scientists have
also postulated that a major mantle plume event
could have been the cause of the mass extinction’s
that occurred at the end of the Cretaceous period
65 million years ago and included the demise of
the dinosaurs.
