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No. 108: Nov-Dec 1996

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Earthquakes And Mima Mounds

In a recent paper in Nature, P.B. Umbanhower et al described how they created regular geometric patterns in a layer of fine particles (only 0.15 mm in diameter) spread on a vibrating surface. At various forcing frequencies, they saw the layer of tiny brass spheres heap up into hexagonal honeycombs, circular piles, and even stranger shapes.

(Umbanhower, Paul B., et al; "Localized Excitations in a Vertically Vibrated Granular Layer," Nature, 382: 793, 1996)

Comment. Nothing anomalous here, you say? Quite right, but perhaps there is in this experiment an explanation of a long-recognized geological anomaly: The origin of the famed Mima Mounds found scattered by the thousands in various regions of the planet, such as Mima Prairie near Puget Sound, in Washington State.

Actually, the demonstration of Umbanhower et al was preceded by a similar experiment back in 1990. In that year, A.W. Berg reported in Geology how he had covered a piece of plywood with a thin layer of fine sand (loess) and subjected the plywood sheet to impacts simulating earthquakes. Lo and behold, the sand rose up in an array of Mima Mound-like heaps. (See: SF#69 and p. 201 in the book Science Frontiers. This book is described here.

Umbanhower, a physicist, probably doesn't read Geology, but the results of his team's experiments certainly confirm Berg's simpler experiments and support the idea that quakes molded the Mima Mounds.

Patterns of tiny brass spheres created by different forcing frequencies Patterns of tiny brass spheres created by different forcing frequencies. Were Mima Mounds piled up by quakes.

From Science Frontiers #108, NOV-DEC 1996. 1996-2000 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