A King's Cubit

Historical Metrology and a Reconsideration of the Toltec Module

– Aiming at a Blurry Target
– Statistical Background I
– Statistical Background II
– Target Practice
Discussion and Conclusions
(On Measurement is Founded...?)


Added August 2008: Surreptitious Mitten Measures and other Non-Metric Musings
A Reply to Nancy White's Questions Posed in The Arkansas Archeologist

by Gregory Vogel

            Archaeologists and other researchers have occasionally "discovered" measurement systems used by prehistoric people in North America and elsewhere.  This paper demonstrates serious problems with many of these discoveries.  Methodologically and theoretically, deriving prehistoric measurement systems from the evidence left to us today is difficult if not impossible in nearly all situations.  The "Toltec Module" is one such fatally flawed measurement.

            More than just debunking the Toltec Module, this paper also explores the methods and theories behind historical metrology (the study of past units of measurement), and more specifically, what I am calling cryptometrology (the search for past units of measurement).

            (The Toltec Mounds site, by the way, has nothing to do with the Toltecs of ancient Mexico – it is a 1,000 year old Native American site in central Arkansas.)  

            You can read the paper section-by-section with the links on the left.  I've also included a very brief, non-technical explanation of some of the main points below.

            The first introduction wasn't part of the original article, it's a short piece I wrote just for fun.  What's spatial statistical analysis for if not for fun?

Brief Description of the Paper:

            The "Toltec Module" was proposed as a discrete measurement used by prehistoric people in eastern North America. Just as we use inches, feet, and miles (or centimeters, meters, and kilometers), the Toltec Module was proposed as a unit of measurement 47.5 meters long (about 156 feet). This has been more-or-less accepted in the archaeological literature, and cited in numerous papers and books as fact.

            Two archaeologists first came up with the 47.5 meter distance from the Toltec Mounds site in central Arkansas.  They measured distances between the edges and centers of earthen monuments at the site, and quite a few other "target" points they thought might be significant.  From their measurements, they thought that multiples of 47.5 meters occurred quite commonly. This was their evidence for the Toltec Module distance.

            The problem is, the archaeologists who proposed this unit of measurement didn't take a lot of things into account – their methods and theoretical justification were totally inadequate.  There were many problems with the study: They assumed that the edges of the prehistoric earthen mounds (which are several centuries old) are exactly today as they where when the mounds were first built, they didn't look for other potential units of measurement (although that really wouldn't have made a difference, as I explain in the paper), they didn't consider that the mounds changed shape and size in significant ways as they were built, and they didn't determine the statistical background of measurements at the site.  They also used an unacceptably large margin of error that increased greatly with distance, so that nearly every measurement by their reckoning appeared to "fit" with a Toltec Module distance even when it didn't.

            In this paper, I use GIS (Geographical Information Systems) to explore the statistical background of measurement to and from mounds at the Toltec Mounds site.  From this analysis, it is clear that 47.5 meters does not occur more commonly than any other measurement, and the "Toltec Module" does not stand up to scrutiny.

            Aside from the statistical analysis, I discuss several theoretical problems with the Toltec Module and other similar studies in general – why it is difficult or impossible to determine past units of measurement from simply measuring distances between "target" points today.

(You can use the links on the left to read through the paper, or proceed straight to the abstract here.)

This site is based on a paper I wrote for the journal Southeastern Archaeology (published in 2006, Vol. 25, pp. 6-19: Historical Metrology and a Reconsideration of the Toltec Module). 

(You can see more of my archaeologically related papers here.)

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