According to Jordan, the anomalies are analogous to continents on the surface of the earth, because they can't be accounted for by temperature variations but must reflect some compositional change as well. These features 'represent the scum or slag that sits up on the outer core boundary, just as continents sit on the outer surface of the earth,' he says. Some have even speculated that these subterranean chunks of debris are pieces of surface continents that were subducted at the plate boundaries long ago. There are, after all, missing pieces in the continental drift jigsaw puzzle. There might even be substantial chunks of asteroids and comets down there waiting, like the Titanic, to be explored by scientific instruments.
Earthquake waves allow seismologists to construct models of the earth's interior.
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