Coso artifact

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The Coso artifact is an object claimed by its discoverers to be a spark plug found encased in a lump of hard clay or rock on February 13, 1961, by Wallace Lane, Virginia Maxey and Mike Mikesell while they were prospecting for geodes near the town of Olancha, California, and long claimed as an example of an out-of-place artifact.[1]

If a spark plug is encased in a 500,000-year-old "geode," this finding would represent a substantial scientific and historical anomaly, as spark plugs were invented in the 19th century. Critics have argued, however, that the concretion, not geode, containing the Coso artifact can be explained by known natural processes and credible evidence for it being 500,000 years old is completely lacking.


Following its collection, Mikesell destroyed a diamond-edged blade cutting through the rock containing the artifact and discovered the item.[1] In a letter written to Desert Magazine of Outdoor Southwest a reader stated that a trained geologist had dated the nodule as at least 500,000 years old and contained a manmade object.[2] The identity of the alleged trained geologist and means of geologic dating were never clarified, nor the findings ever published in any known periodical.[1] Furthermore, at the time that Maxey reported the Coso artifact as having been dated as being 500,000 years old, there was no known method, including the use of guide fossils, by which either the artifact or concretion could have been dated as being this old.[3] The nodule surrounding the spark plug may have accreted in a matter of years or decades, as demonstrated by examples of very similar iron or steel artifact-bearing nodules, which are discussed and illustrated by Cronyn.[4]

Criticism and analysis[edit]

The origin of the artifact has been the cause of much speculation.[1] Pseudoscientific suggestions for the artifact's origin have included:

An investigation carried out by Pierre Stromberg and Paul Heinrich, with the help of members of the Spark Plug Collectors of America, suggested that the artifact is a 1920s Champion spark plug. Chad Windham, President of the Spark Plug Collectors of America, identified the Coso artifact as a 1920s-era Champion spark plug, which was widely used in the Ford Model T and Model A engines. Other spark plug collectors concurred with his assessment.[1]

Stromberg and Heinrich's report[1] indicates the spark plug became encased in a concretion composed of iron derived from the rusting spark plug. It is typical of iron and steel artifacts to rapidly form iron oxide concretions around them as they rust in the ground.[4]

The location of the Coso artifact is unknown as of 2008. Of its discoverers, Lane has died, Maxey is alive but avoids public comment, and the whereabouts of Mikesell are not known.

See also[edit]


  1. ^ a b c d e f Stromberg, P., and P. V. Heinrich, 2004, The Coso Artifact Mystery from the Depths of Time?, Reports of the National Center for Science Education, v. 24, no. 2, pp. 26–30 (March/April 2004).
  2. ^ Maxey, V., 1961, The Coso Geode... in Letters...From Our Readers. Desert Magazine of Outdoor Southwest. v. 25, no. 5, p. 4. (May 1961).
  3. ^ Walker, M. (2005) Quaternary Dating methods Wiley, New York, New York. 304 pp. ISBN 978-0470869277.
  4. ^ a b Cronyn, J. M. (1990) The Elements of Archaeological Conservation Routledge, New York, New York. 326 pp. ISBN 978-0415012072.

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