Wednesday, May 27, 2009

Scientific Discovery: Dating Pottery By Measuring Rehydroxylization

Scientists at the University of Manchester announced last week a breakthrough in the dating of ceramic (pottery) objects.  Called rehydroxylation dating, "the method relies on the fact that fired clay ceramic material will start to chemically react with atmospheric moisture as soon as it is removed from the kiln after firing. This continues over its lifetime causing it to increase in weight – the older the material, the greater the weight gain." Initial tests on materials up to 2,000 years old have been accurate within a decade.  If this method proves reliable in dating earlier objects, it could be quite useful in solving, for instance, the current debate over 10th-9th century BC pottery in Israel.  One problem with this method for archaeological sites is that the “internal clock” of the pottery is “reset” if the temperature reaches 500 degrees Celsius.  Thus the pottery from areas destroyed by fire would only date to the year of the destruction and not to the date of creation.

The results of the report are covered in a popular article by Science Daily, or you can read the original article (pdf) in the Proceedings of the Royal Society A (alternate link here).  The paper’s abstract:

The majority of ceramics are found in archaeological deposits and are extremely difficult to date. The typical method of using radiocarbon dating used for bone or wood cannot be used for ceramic material because it does not contain carbon, and luminescence dating is far too complex. Scientists from the Universities of Edinburgh and Manchester have discovered a new method of ceramic dating which is published in Proceedings of the Royal Society A..

Their new 'rehydroxylation dating' method stems utilises the fact that fired clay ceramics start to react chemically with atmospheric moisture as soon as it is removed from the kiln. The ultra-slow recombination of moisture appears to be generic in fired-clay ceramics and obeys a precise power law, which acts as an 'internal clock'. Rehydroxylation dating enables scientists to date brick samples from Roman, medieval and modern periods.

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3 Comments:

  • maybe it isn't such a bad thing that the dating can only accurately be assigned back to the original kiln date or when the temp reached 500 Celsius. I would think that being able to date pottery from Jericho and Hazor and other sites like it could help to finally put to death some of the early-exodus, late-exodus debate.

    By Blogger Jeff, at Wed May 27, 10:31:00 PM  

  • I don't know as much about archaeology as I would like, but my guess is that if this really works as claimed it could have significant ramifications for the way things are dated and could possible turn a number of assumed dates on their heads.

    By Anonymous Al Sandalow, at Thu May 28, 03:44:00 PM  

  • Al, don't get your hopes up. Rocks from the 1980 Mount St. Helens eruption have been dated radiometrically to hundreds of thousands of years. Most scientists still believe the Earth & universe are billions of years old as "proven" by radiometric dating. This new method already has the caveat that it can't date things too old; it can only date them too young. So when pottery from this method turns out younger than expected according to conventional chronology, no big deal ... must've gotten re-fired at that later date.

    By Blogger G.M. Grena, at Fri May 29, 10:31:00 PM  

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