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No. 53: Sep-Oct 1987

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Meteor-impact winters, magnetic field reversals and tektites

"Nuclear winter" is a term now in vogue. And, believe it or not, the rains of tektites discussed below may have been the forerunners of climatic catastrophes similar to the postulated nuclear winters. We shall call them "meteor-impact winters.

First, a tad of background: Great meteor impacts and tektite events seem to have occurred nearly simultaneously with deep-cutting biological extinctions and reversals of the earth's magnetic field. Ever since this apparent synchrony was recognized a few decades ago, theorists have been vying in generating scientific scenarios, especially some mechanism that would reverse the earth's magnetic field.

New entrants in the lists are R. Muller and D. Morris, two Berkeley physicists. Here is how they see it:

"A sufficiently large asteroid or cometary nucleus hitting the Earth lofts enough dust to set off something like a 'nuclear winter.' The cold persists long after the dust settles because of the increased reflectivity of the snow-covered continents. In the course of a few centuries, enough equatorial ocean water is transported to the polar ice caps to drop the sea level about 10 meters and thus reduce the moment of inertia of the solid outer reaches of the Earth (crust and mantle) by a part in a million. 'That doesn't sound like much, Morris told us. 'But when we realized that this translates into a full radian of slippage between mantle and core in just 500 years, we began to look seriously at the consequences.' With the moment of inertia of the crust and mantle 'suddenly' decreased, the argument goes, they begin spinning faster than the solid-iron inner core at the center of the Earth. The 2300-km thick shell of liquid outer core that separates the mantle from the inner core thus acquires a velocity shear, which in the course of about a thousand years destroys the pattern of convective flows that served as the dynamo maintaining the Earth's dipole field."

The field reversal is not immediate according to both calculations and analyses of sediments. After the impact event, the dipole field decreases for a few thousand years, followed by a longer hiatus. Then, there is a sudden reversal. (Schwartzschild, Bertram; "Do Asteroid Impacts Trigger Geomagnetic Reversals?" Physics Today, 40:17, February 1987.)

Comment. In trying to relate all this to our present situation, recall that a major "ice age" is just a few millenia behind us, and our dipole field has been decreasing slowly for as long as we have been able to measure it. Brace yourselves!

Reference. There are many anomalies associated with the tektites. See ESM3 in our catalog: Neglected Geological Anomalies. Ordering information here.

From Science Frontiers #53, SEP-OCT 1987. 1987-2000 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