Tuesday, May 22, 2007

Engineering the Pyramids?

Dr. Michael Barsoum of Drexel University heads a group which is asserting that blocks of artificially reconstituted limestone make up part of some Egyptian pyramids. My initial impression that their knowledge of limestone and sedimentary petrology is limited was only partially assuaged by reading their paper published in the Journal of the American Ceramic Society1. In spite of detailed SEM examination and chemical analysis of numerous samples from neighboring natural outrcops and from the pyramids, only the novel hypothesis of an artificial block cemented with "geopolymer" is really fleshed out.

There are much simpler alternative hypotheses that would account for amorphous silica and microcrystalline dolomite as replacing cements either in the genesis of the limestone or in the weathering of the stone blocks after the pyramids were built. Dr. Barsoum is to be commended for creating a blog in which to promote his ideas and answer criticisms. His reponses to the criticisms that have been posted are quite strident and do not show much consideration of alternative hypotheses.

A similar sort of sensationalized "mystery" about the age of the Sphinx has been kept before the public eye by Dr. Robert Schoch of Boston University. Egyptology does attract advocates for extreme ideas and fanciful theories, although it must be acknowledged that Dr. Barsoum is himself Egyptian and has already had a successful career as an engineer and materials scientist. Barsoum does not appear to have a financial or professional interest in sensationalizing his findings, and he is promoting some novel applications of the geopolymer technology for building inexpensive housing in the developing world.

1Barsoum, Michael W., Ganguly, A., and Hug, G., 2006, Microstructural Evidence of Reconstituted Limestone Blocks in the Great Pyramids of Egypt. Journal of the American Ceramic Society 89(12): 3788-3796.

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At 9:47 PM , Blogger GeologyJoe said...

I also watched the video you posted about this. very interesting. However, I would think that the engineered blocks would/could not have lasted as long as cut stone blocks.

At 7:06 AM , Blogger Don Thieme said...

That would be an interesting aspect of the controversy. It does seem like silica cementation might make for a more resilient limestone. Perhaps you are right, though, that the artificial version would be less resilient than the natural.


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