Teotihuacan sherds

Activation analysis of selected groups of sherds of typically Oaxacan and Teotihuacan ceramics has shed some light on the question of the Oaxacan presence at Teotihuacan and the related concept of long-distance trade between the two centers during early Classic times. Studies of Preclassic Tlatilco figurines reveal them to have been locally manufactured. 

The first problem was posed to us by Evelyn C. Rattray, who also supplied the relevant sherds and clay samples. In one section of Teotihuacan, so many sherds of Oaxacan-style pottery have been found that archaeologists have come to regard the suburb or barrio as a possible site of Oaxacan occupation (4). Inasmuch as the home of Oaxacan pottery is located in the Monte Alban region some 400 km south of Teoti-... 

Figure 1. Teotihuacan BNL Rattray provenance typical Teotihuacan sherds...

Teotihuacan potters, located in the southern part of the ancient city on grid square S2E1 of the Millon map. The genuine Oaxacan sherds taken for comparison were surface collections from two sites, Caballito Blanco and Dain Zu (Macuilxochitl), located 40 and 22 km (respectively) southeast of Oaxaca while the clay was from the source being used today by the famous potter Rosa of Coyotepec, about 12 km south of Oaxaca. 

Figure 2. Teotihuacan provenance Oaxacan-type sherds ...

Figure 5. Non-matching sherds descriptions given in Table IIL Two modern sherds from San Sebastian Teotihuacan.

An attempt has been made with Figure 6 to present graphically the overall matching data from Teotihuacan. The horizontal lines of the crosses indicate the mean oxide concentrations within the ancient matching sherds while the extent of the vertical lines indicates the spread of... 

Figure 6. Comparison of the concentrations of many oxides in ancient pottery and in modern pottery and clays from Teotihuacan. Average concentrations (—) and 95% confidence ranges ( ) of 23 ancient sherds. Average concentrations (%) in two modem pottery plus two clay specimens.

A ONE STANDARD DEVIATION RANGE OF SPECIMENS FROM V LAYERS 3 THROUGH II AT TEOTIHUACAN WITH OAXACAN STYLE ONE STANDARD DEVIATION RANGE OF SHERDS FROM OAXACA O A OAXACAN STYLE SHERD FROM LAYER 14 AT TEOTIHUACAN... 

Figure 8. Ratios of concentrations in Teotihuacan and Oaxacan sherds to the average concentrations in sherds found at Teotihuacan with total or partial local stylistic characteristics...

The open circles show the relative positions of one Oaxacan style sherd from Teotihuacan which did not conform to the local Teotihuacan composition—specimen 1-21, a polished grey incised bowl from layer 14, the lowest layer sampled at the Oaxacan Barrio. Our data are consistent with the possibility that this sherd was imported from Oaxaca. However, the preponderance of our findings suggests that the tendency was to import potters rather than pots from there to Teotihuacan. 

However, one Oaxacan style sherd from Teotihuacan showed Oaxacan composition and thus was probably imported. Finally, the analysis of a group of six preclassic figurines and a clay from Tlatilco in the Valley of Mexico very strongly suggests that the figurines were also locally made. 

It is logical to consider whether the majolica sherds which were found in Mexico City could have been fabricated of local clay. Fortunately data on clays and related pottery from the Valley of Mexico has been collected at Brookhaven National Laboratory over many years. The ceramic material, which had previously been anlyzed by Harbottle and Sayre in collaboration with other investigators, consisted of Precolumbian artifacts. The pottery and the clays from two archaeological sites within the Valley, Teotihuacan, and Tlatilco were all basically similar in composition, although the clays and pottery from the two separate sites could be diflFerentiated through a subtle multivariate statistical analysis. It is likely that the entire Valley of Mexico is underlain with clay bed of moderately uniform trace impurity composition, and hence if the composition of the Mexico City majolica sherds was similar to that of ceramics and clay from Teotihuacan or Tlatilco, it would be probable that the majolica was fabricated from clays originating somewhere within the Valley of Mexico. 

The high calcium content in the majolica found in Mexico City— 21.4% calculated as pure calcium carbonate compared with 5.9% in sherds of Teotihuacan—suggests that a calcium compound such as calcium or calcium magnesium carbonate may have been added to the majolica either as a temper or through deposition during burial. Petrographic examination of cross sections of representative Mexico City majolica sherds show heavy deposits of birefringent material with structures... 

Petrographic comparison of the Mexico City majolica with Teotihuacan sherds shows that except for the secondary deposition of carbonates, which is present in the majolica but absent in the Precolumbian sherds, the mineral composition of both sets of specimens is very similar. Both notably include hornblende and similar feldspars as inclusions, and both are low in quartz. Similarly, except for the calcite in the majolica, both sets of sherds show similar x-ray diflFraction patterns. The mineralogical evidence, therefore, strongly suggests that both sets of sherds were made from closely related clays and that the compositional diflEerences that exist between them are primarly the result of the accumulation of a secondary calcareous deposit within the majolica sherds during burial in the wet soil of Mexico City. 

We have been able to compare our samples to a small group of majolica sherds from Spain and to a reasonably large group of Precolumbian sherds from Teotihuacan. The majolica sherds from Caribbean sites agree in composition with the Spanish specimens, and those from sites in Mexico City have compositions sufBciently similar to the sherds from Teotihuacan, considering the secondary deposits of carbonates of calcium which are in the majolica sherds and not in the Precolumbian sherds. The presence of these deposits of carbonates of calcium in the majolica and their absence in the Precolumbian sherds was determined by petrographic examination and x-ray diflFraction as well as by elemental analysis. 

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