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No. 55: Jan-Feb 1988

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Cyclothems as solar-system pulse recorders

Geologists can help astronomers look back in time. The sunspot cycle can be seen in variations of varves; i.e., annual layers of sediment; and the growth rings of shells have been used to estimate the number of days in the lunar month when the solar system was younger. Cyclothems may also be useful. Cyclothems are groups or bundles of strata that repeat themselves in stratigraphic columns. A generalized cyclothem from Illinois is shown in the illustration.

In the U.S. western interior, rhythmic sedimentation appears in the Fort Hays Limestone Member of the Niobrara Formation. These cyclothems can be correlated over distances exceeding 800 kilometers and are believed to be the consequence of climatic changes associated with the earth's precession and orbital eccentriciy. These rhythms have been captured in bundles of shale-limestone couplets. A bundle of five coup lets, for example, is thought to express 21,000- and 100,000-year Milankovitchtype climatic cycles, as impressed by variations in the earth's orbital precession and eccentricity.

Analysis of the Fort Hays Limestone Member, however, reveals that while bundles of five couplets do occur, the number may vary from 1 to 12. Clearly, things are not clear-cut.

(Laferriere, Alan P., et al; "Effects of Climate, Tectonics, and Sea-Level Changes on Rhythmic Bedding Patterns in the Niobrara Formation (Upper Cretaceous), U.S. Western Interior," Geology, 15:233, 1987.)

Comment. As the rather comprehensive title of this article states, purely terrestrial forces may alter the rhythm. It may be, though, that cyclothem changes reflect actual changes in the earth's orbit resulting from astronomical catastrophism. The Cretaceous saw many geological and biological changes. Cyclothems may tell us more about them.

Cyclothem from Illinois All ten members are never present at one location. The most common sequences are 1, and/or 2, 4, 5, 8, 9 and 10.

From Science Frontiers #55, JAN-FEB 1988. 1988-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

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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