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No. 47: Sep-Oct 1986

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Continental graveyard?

The seismic waves generated by earthquakes penetrate deeply into our planet and allow geophysicists to, in effect, X-ray the earth. In addition to the hypothesized solid inner core, the fluid outer core, and the encapsulating solid mantle, there seems to be continentsized inhomogeneities in the vicinity of the mantle and the outer core. The anomalous seismic signals can be interpreted as huge blocks of different composition and/or temperature.

T.H. Jordan, from MIT, ventures:

"...that what they have mapped are 'continents' on the core-mantle boundary. 'What we've seen is something really incredible,' he says. 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. Can once-subducted continents and cosmic debris ever rise again?

(Weisburd, Stefi; "Seismic Journey to the Center of the Earth," Science News, 130:10, 1986. Also: Kerr, Richard A.; "Continents at the Core-Mantle Boundary?" Science, 233:523, 1986.)

Earthquake waves allow seismologists to construct models of the earth's interior Earthquake waves allow seismologists to construct models of the earth's interior. Coninent-sized inhomogenities have been found near the core-mantle boundary.

From Science Frontiers #47, SEP-OCT 1986. 1986-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987