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The cretaceous-tertiary extinction bolide

The recently discovered worldwide iridium-rich layer is taken by many scientists as evidence of the collision of an asteroid or comet with the earth about 65 million years ago. This cataclysmic event is also blamed (by some, at least) for the apparent sudden biological extinctions recorded on these pages of the fossil record. In this setting, the authors of this paper calculate the effects on the earth of a 10-kilometer-diameter object impacting at about 20/km/sec.

Do the theoretical results jibe with the geological and paleontological data? Very definitely. Crater ejecta rich in extraterrestrial material would be blasted to an altitude of 10 km, where winds would insure global distribution. In terms of biological stress, the 10-km projectile would transfer 40-50% of its kinetic energy to the atmosphere, creating a heat pulse that could raise global temperatures 30C (50F) for several days. Many large animals might well succumb to such a temperature transient. In addition, the protective ozone layer might be blown away by shock waves and not reform for a decade.

(O'Keefe, John D., and Ahrens, Thomas J.; "Impact Mechanics of the Cretaceous-Tertiary Extinction Bolide," Nature, 298,123, 1982.)

Reference. We catalog biological extinctions at ESB1 in Anomalies in Geology. To order this book, visit: here.

Particle velocity flow field from a silicate projectile impacting a strengthlessness silicate surface Fig. 1. Particle velocity flow field from a silicate projectile impacting a strengthlessness silicate surface at 15 and 45 km s-1. Flow fields at a, t = 8.2; b, t = 3.1 where r is normalized time.

From Science Frontiers #23, SEP-OCT 1982. 1982-2000 William R. Corliss

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  • "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