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No. 43: Jan-Feb 1986

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The Cretaceous Incineration

The worldwide deposit of iridium at the end of the Cretaceous implies, to many at least, that the great biological extinctions of this period were the consequence of a meteorite impact. It has now been discovered that clay samples from the Cretaceous-Tertiary boundary also contain 0.36-0.58% graphitic carbon. It is fluffy stuff and suggests that the planet was once covered by a thick layer of soot. Quantitatively, the soot layer is equivalent to the carbon in 10% of the earth's present biomass. The authors speculate that this soot was created by huge wildfires that consumed much of the earth's vegetation and perhaps fossil fuel as well. Terrestrial life was, of course, devastated -- just as it is in the currently popular "nuclear winter" scenarios. The end-of-the-Cretaceous soot is in fact, thicker and more widely spread than nuclear winter theories predict.

(Wolbach, Wendy S., et al; "Cretaceous Extinctions: Evidence for Wildfires and Search for Meteoric Material," Science, 230:167, 1985.)

Comment. Questions arise, though: How could a single meteorite impact ignite worldwide wildfires? Why haven't other meteorite impacts, recorded abundantly by large craters and astroblemes, also set fire to the planet and left iridium layers?

From Science Frontiers #43, JAN-FEB 1986. 1986-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "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