Diachronic and Synchronic Analyses of Obsidian Procurement in the Mixteca Alta, Oaxaca

Intra- and Interregional Interaction: Diachronic and Synchronic Data

As stimulating as the trial project data were, the interpretive power of this small sample without comparable material from elsewhere in the Mixteca Alta remained limited. Thus, with the assistance of FAMSI, a much larger sample was sourced through INAA from both the Cruz B and Yucuita phases at Etlatongo. In addition to more samples from Etlatongo, I collaborated in obtaining samples from sites excavated by other archaeologists throughout Oaxaca state. The sample analyzed by MURR now includes 410 obsidian fragments; an additional sample (ET195; see Appendix 1) was revealed to be chert, not obsidian, and will not be further discussed.

The Larger Cruz B sample from Etlatongo

Combined with the initial 45 samples, a total of 207 Cruz B obsidian fragments have been sourced by INAA. Rather than biasing the sample by selecting only certain obsidian fragments from each context, all obsidian fragments from discrete archaeological features and strata were analyzed in order to understand different consumption choices at Etlatongo. The following contexts are employed:

1. The majority of Etlatongo obsidian samples (n = 128) derive from the earliest occupations explored during the 1992 project. A series of features and surfaces, representing several occupations, are here grouped under the term EA-2 (Excavation Area 2), a 5 × 7 meter unit that exposed a series of houses that, based on both architectural and ceramic features, I have interpreted as higher status.

2. Unit 22, located along the eastern edge of the southern portion of the site, exposed a Cruz B surface with an associated bell-shaped pit (Feature 3) – the largest known from Etlatongo. All 37 obsidian fragments from Feature 3 were analyzed through INAA. The amount of exotic goods and ritual paraphernalia also suggest the residents were of higher status.

3. Unit 1, placed on the southern-most mound at Etlatongo, exposed a series of strata that elevated several surfaces in what I have identified as a possible public space at Etlatongo. A total of 28 obsidian fragments came from the earliest modifications of this space and were analyzed by INAA.

4. Units 15 and 16 exposed a series of Cruz B occupations. Those of Unit 15 appear to be of average status, while those revealed by Unit 16 are best categorized as higher status. The few obsidian fragments that came from these contemporaneous deposits were analyzed with INAA: 8 from Unit 15, 6 from Unit 16.

INAA of the Cruz B sample provides additional insight into consumption and economics at Etlatongo, as well as adding two obsidian sources that were not previously identified at Etlatongo: Cruz Negra, Michoacán and Tulancingo, Hidalgo. The data are summarized in Table 1, shown below, while compositional data are detailed in Appendix 1.

The results of the INAA for the Cruz B sample are quite provocative. Additional obsidian sources are present at Etlatongo that have not been documented at contemporaneous Valley of Oaxaca sites, although those data were gathered nearly 30 years ago and may not be fully comparable (Flannery 1976; Pires-Ferreira 1975). Clearly, ancient villagers at Etlatongo participated in a variety of exchange networks. While most households relied on obsidian from Paredón, which constitutes 65% of the total Cruz B sample, each higher status household had access to at least one source that the others did not. It is noteworthy that the one average household sampled, Unit 15, had access to only two sources – Paredón and Guadalupe Victoria. Even the household represented by Unit 16, with fewer obsidian fragments recovered than Unit 15, had four sources utilized. The other higher status households each had five sources. While the sample from Unit 22, Feature 3 had the only samples from the Pico de Orizaba and Tulancingo sources, the households represented by EA-2 accessed West Mexican sources. In addition to Ucareo, Michoacán, the only archaeological example to this date at MURR of an obsidian fragment from Cruz Negra, Michoacán came from EA-2 (Glascock 2004, personal communication). Additional sources are represented in the strata associated with a possible public structure at Unit 1, where the only fragments from Guatemalan sources – El Chayal and Ixtepeque – appear. No fragments come from Guadalupe Victoria in these Unit 1 deposits. Thus, the results show networks of individual access to exotic sources beyond those commonly utilized by nearly every household (Paredón and Otumba), where choices reflect negotiations of access both within Etlatongo and in relations with other Early Formative communities.

Additional Early Formative sources from the Mixteca Alta and Adjacent Regions

A problem with the original pilot study is the lack of context for the results in the Mixteca Alta. I focused on samples from the Nochixtlán Valley as well as regions that may have played a crucial role in trade routes. Obsidian from Cruz A and Cruz B occupations at the Nochixtlán Valley site of Yucuita were sourced. While Cruz B samples were especially desired, only three could be located. Fortunately, an additional 42 samples from Cruz A occupations at Yucuita were located for analysis. In order to understand movement of obsidian into the Nochixtlán Valley, an additional 21 samples were sourced from Rancho Dolores Ortíz, a Cruz A village located approximately 200 km east of Yucuita in the Cuicatlán Cañada. While Yucuita is 25 km closer to a major Formative obsidian source than is Rancho Dolores Ortíz, the Cañada site contained triple the amount of obsidian. It has been hypothesized that Rancho Dolores Ortíz was a central node in this exchange network (Winter 1984). Included with this sample was one additional obsidian fragment from the Mixe area of Oaxaca; the sample was collected from the surface, so it is not possible to determine from which phase of the Formative it pertains. While it was hoped that contemporaneous obsidian samples from the Valley of Oaxaca could be obtained, it appears most of the obsidian from excavations conducted 30 years ago have been misplaced or are simply unavailable.

While more samples from Cruz B deposits in the Mixteca Alta and Cuicatlán Cañada would be desirable, the data clearly show the importance of the Guadalupe Victoria obsidian source in the Mixteca Alta. All Cruz B obsidian from Yucuita is from that source, as are most of the Cruz B samples. The only other obsidian source represented at Yucuita is Pico de Orizaba – a source geographically close to Guadalupe Victoria (see Figure 1).

The same pattern prevails at Rancho Dolores Ortíz (combined in Table 2 with one obsidian fragment from the Cruz A Mixe site of Zacatepec), with 90% of the obsidian from Guadalupe Victoria. One surprise is the presence at Rancho Dolores Ortíz of Guatemalan obsidian – from El Chayal. This suggests the strategic location of Rancho Dolores Ortíz not only permitted the site to funnel obsidian from the Central Highlands and Veracruz into Oaxaca, but also connected it to exchange networks that trafficked in Guatemalan obsidian. The virtual absence of the major Cruz B obsidian source at Etlatongo – Paredón – at Yucuita and Rancho Dolores Ortíz is significant, and illustrates the dramatic transformations in interregional interaction and social complexity emblematic of the Cruz B phase.

Diachronic Change

The initial sample from Etlatongo only focused on Cruz B contexts; I also wanted to understand changes in obsidian procurement through time. The later Yucuita phase represents a time of significant changes in socio-political complexity (Blomster 2004). Obsidian analysis can assess the impact of new urban centers on exchange and procurement economies. I selected all (n = 93) obsidian fragments from Yucuita phase deposits associated with houses in Excavation Area 1 (EA-1) and from a storage pit in Unit 6 (n = 13). In order to place these in a larger context, Late Formative obsidian was sourced from Monte Albán (n = 15), the center of the Zapotec state in the Valley of Oaxaca, and Carrizal (n = 16), located on the Isthmus of Tehuantepec. These data are summarized in Table 3.

The Yucuita phase data show changes in economic patterns during the Late Formative period at Etlatongo. The Paredón source, while still the most important, no longer constitutes over half of all obsidian at Etlatongo. The decreased utilization of the Paredón source, however, is not balanced by increased number of sources utilized; the total number of obsidian sources is one less, eight, than during Cruz B. The sources, however, change; West Mexican sources seem to decline in importance, while two more sources from the Mexican highlands – Pachuca and Zaragoza – become important.

Comparison with Monte Albán, the center of the emerging Classic Zapotec state in the Valley of Oaxaca, shows a decreased variety of sources. Only five sources are represented in the sample tested by INAA, and of these the Paredón source constitutes the vast majority (73%) of the sample. The nearly total focus on the Paredón source at Monte Albán also contrasts with the obsidian analyzed from Carrizal. This site, located along important Isthmus of Tehuantepec trade routes, contained no examples of the Central Mexican highland sources – Paredón and Otumba – so important at Etlatongo and Monte Albán. Instead, obsidian sources represented are much more evenly divided between six sources, two of which (Chayal and San Martin Jilotepeque) are Guatemalan. West Mexican sources are absent in the Carrizal sample, while the important Guadalupe Victoria source in Puebla is the most frequent (25%). Carrizal was located adjacent to Isthmus trade routes that channeled Guatemala obsidian into the Southern and Central Highlands.

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