Activation analysis study of Preclassic ceramics from the Capacha phase (Colima) and El Openo (Michoacan) [report]

G. Harbottle
1973 unpublished
Several years ago, as a result of correspondence with Dr. Isabel Kelly, we undertook the analysis of two groups of Predassic sherds from West Mexico, dating to the Formative Period, ca. 1500 B.C. Although these sherds were found in geographically widely separated contexts, they were considered by the archaeologists, Drs. Kelly and Oliveros, to be remarkably similar stylistically. The question was posed whether, by neutron activation analysis, we could establish (or contradict) a possible common
more » ... clay source origin. The sherds and their proveniences are given in Table 1 . The activation data were originally obtained about two years ago and an interim report to Dr. Kelly in the form of a letter (June 11, 1971) noted that the Colima sherds KE 01, 02, 03, 04, OS, 06, 08, 11 and 12 were similar, while KE 07 and 09 were different (though not much different). Among the Openo sherds only OP 01 showed any similarity to any of the Colima sherds, and then only to KE 07 and 09. The technique used for matching the compositional profiles was that reported in Abascal et al.the Potplot-Potstat technique, which depends to some extent on subjective impressions, backed up by statistical analyses. We have now reexamined the data, making use of the numerical 2 taxonomy program "NADIST" which generates a matrix of mean Euclidean 3 distance coefficients between all possible pairs of samples. The relevant matrix is presented in the appendix. We also employed a second new technique, the scandium-iron correlation (ratio) index, based on our observation that both in the Middle East and in some portions of Mesoamerica the scandium and iron in pottery clays tend to be highly correlated with one another, i.e., the concentrations of scandium and iron obey the equation Table 1 BNL Site Number
doi:10.2172/4840002 fatcat:wrpixbnc3zfkfiyevkmyznwcku