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FAMSI © 2000: Glenn Stuart |
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Archaeological Palynology of Teuchitlán Field Strategies A standard sampling protocol for habitation sites is to collect samples from floors uncovered during excavation (cf. Fish, 1998). Such a protocol has the advantage of providing samples from similar depositional contexts known to have been exposed to pollen deposition during occupation of the site, thereby producing comparable data sets. Such a protocol was difficult to realize at Teuchitlán for two reasons. First, the site is not predominately a habitation site, so the number of rooms is limited, presumably occurring only on the platforms. Second, the fact that excavation consisted predominately of trenching rather than opening-up excavation blocks means that floors that might be encountered were not as extensively exposed. Where excavation was more laterally extensive, it was only being conducted to a depth sufficient to expose in situ rock and rock alignments for mapping; at the time of my visit, no floors on the platform mounds had been exposed. On the other hand, a floor or floors were uncovered in three locations within the ballcourt, all three were sampled. Samples from a variety of other contexts were also obtained. The collection of the samples took place in late November 1999, just prior to termination of the field season. At this time, excavation of the site had consisted of clearing the surface vegetation and removing loose sediment from pyramid #2, as well as from three of the platforms surrounding this pyramid. The ballcourt, laying between circles 1 and 2, had also been cleared. Several trenches had been excavated within these areas; those with stable sides had been left open for my examination. Samples were collected from the walls and faces of the trenches; such samples consisted of collecting material from a 5 centimeter x 5 centimeter area. Where floors and other surfaces were exposed, pinch samples – that is, the collection of a small pinch of material from several different spots within a defined chronologically synchronous area – were also obtained. A total of 184 samples were collected. Most of the samples were collected from construction fill. The most common fill material was clay carried up from the lake (now Presa de la Vega) lying several hundred meters from the site. As a lacustrine clay, it is likely that this material contained fairly high concentrations of pollen. However, transportation and using it as fill apparently introduces both oxygen and microorganisms into the clay, thereby diminishing or even eliminating the original pollen content (J. Schoenwetter, 2000 personal communication). Thus, pollen within this sediment may date to the period of its use as construction fill and therefore directly to site occupation. The question then becomes whether or not the clay was exposed long enough to trap sufficient quantities of pollen for analysis. The second most common construction fill, aside from rock, was puddled adobe; whether this material would even contain pollen is uncertain, but again, transportation of the material to make the adobe, and production of that adobe may well eliminate whatever pollen was previously present. The adobe, as well as a kaolin-rich clay that was not commonly present in the areas I sampled, was applied moist, allowed to dry, then covered with clay fill; the sequence then being repeated as necessary (P. Weigand, 1999 personal communication). How long the adobe was left to dry before being covered would be critical in regard to the amount of pollen that may be deposited on it. These contexts were thought important to sample because if they did contain sufficient pollen for analysis, they would provide a chronological sequence directly tied to construction episodes. The final sampling context consisted of soil that pre-dated site construction. Such samples are particularly important as they would evidence what the vegetation and environment were like prior to site construction. However, as they appeared to be of aeolian origin, it was thought that they may not have represented a very stable surface upon which pollen could accumulate, so again their pollen concentrations may be quite low. This soil was also only rarely encountered; there were only two locations where this soil was able to be sampled. The final type of sediment from which samples were collected was a volcanic ash-rich fill that was predominately used as a basal fill placed over top of and amongst bedrock outcrops. It seems unlikely that this material would contain pollen, but was sampled anyway. None of this material has yet been processed for pollen analysis. In sum, most of the available contexts, and the sediment / material they contained, were not of the sort that routinely provide good pollen samples. They were, nevertheless, sampled extensively to see what they may contain. Excavation on the patio of circle 1 consisted of a units 1 x 2 meters in size excavated through the more than 2 meters of patio fill to bedrock (Figure 4, below). The profiled face of one of these units was sampled at 10 centimeter intervals to obtain a complete fill sequence. Given that samples were taken from 5 cm x 5 cm areas, this means there is actually only a 5 centimeter gap between samples. A total of 24 samples were collected from the circle 1 patio.
The only floors exposed prior to or during my visit were in the ballcourt, where three different sections of floor were exposed (Figure 5). Whether all three of these sections are from one contemporaneous floor or from more than one floor is unknown; all appear to be from the same depth and have the same color and consistency, but this may not be indicative of contemporaneity. A pinch sample was recovered from each of these floor sections. Four of the ballcourt trenches were being excavated to follow the upper and lower walls that lie along either side of the ballcourt and run parallel to the long axis of the court (Figure 6). Samples were taken from the soil immediately below the bottom course of these walls.
A test pit excavated through the ballcourt fill down to bedrock was sampled according to the same procedure used for the circle 1 patio. This pit indicated that the fill extended for more than 1 meter. A total of 46 samples were collected from various locations within the ballcourt. Excavation at pyramid 2 consisted of clearing off the vegetation and loose soil from the entire pyramid, excavating trenches into the side of the pyramid to attempt to document construction episodes, or doing shallow excavations to expose the tread and rise sequence of the step-sided pyramid (Figure 7).
Samples were collected from vertical faces within the trenches to document construction episodes as revealed through sequences of 5 to 15 centimeter thick clay and rubble fill capped with puddled adobe varying in thickness from about 2 to 5 centimeters. Both the fill and the adobe were sampled. Samples were taken from the base of the pyramid where it sits upon bedrock, to the top of the pyramid, as excavation allowed. As the trenches from which these samples were obtained have not been excavated very far into the pyramid, the fill sampled probably dates from relatively late (recent) building episodes. Samples were also collected from the exposed steps of the pyramid, with one or two samples collected from each tread and rise. There was no evidence of a plastered floor or prepared sub-floor on the treads, or of the rises having been plastered. There is also no evidence to indicate that these steps functioned as stairs, aside from the one area that Weigand has specifically hypothesized to be a stairway, or that any of the surfaces sampled were exposed while the site was occupied. Toward the top of the pyramid, but only a few centimeters below the current ground surface, excavation revealed a packed surface that was interpreted as being prepared for a floor, but if a floor had been constructed on this surface, it has eroded away. This prepared surface was, nevertheless, sampled. A total of 74 samples were collected from pyramid 2. A trench excavated into this platform also revealed it to be step-sided (Figure 8). In this case, the fill and rises appeared to be of clay, with the tread being capped by rock. There was no evidence of a plastered floor or prepared sub-floor on the treads, or of the rises having been plastered. The use of puddled adobe capping clay fill was as seen for the pyramid. Samples were collected from both the tread and rise portions of the step, and from the clay fill / adobe sequences. Two of the trenches were also excavated down into what appeared to be original soil, that is, soil that was present prior to construction of the sites architectural elements. This soil appeared to be aeolian, and therefore less likely to contain sufficient concentrations of pollen for analysis, but was collected. A total of 29 samples were collected from platform 1 of circle 2. Clearing of surface vegetation plus loose rock and soil on circle 2 platform 3 resulted in the exposure of what may have been the foundations for a couple of small structures plus one larger structure (Figure 9). Pinch samples were recovered from within each of these structures, as well as from four of six areas along the edges of the platform that were relatively rich in pebbles and small cobbles, two of the four areas between these pebble patches that did not contain the pebbles, plus along the pronounced step running along the front of the platform. Thus a total of 10 pinch samples were obtained from this platform.
Adobe, believed to be from a wall, and covering an approximately 25 centimeter x 25 centimeter area was uncovered during excavation. A sample of this adobe was collected, but has not yet been processed. |
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