Isla Agaltepec: Postclassic Occupation in the Tuxtla Mountains, Veracruz, México

Surface Survey and Artifact Analysis

In-depth analysis of the Isla Agaltepec material is ongoing. Nonetheless, several general observations can be made here. The available data suggest a Postclassic (A.D. 1000-1521) occupation of the island. Moreover, these preliminary findings indicate that different portions of the island may reflect different occupational episodes, perhaps earlier and later phases of the Postclassic. Finally, patterning in the spatial data can be used to infer functional differences among the three areas investigated.

Two-hundred and forty-four systematic collections were obtained across the island, generating a total of 4321 artifacts that weighed almost 23 kilograms. Pottery is by far the single largest contributor to these figures (Table 1, shown below), with chipped-stone artifacts a minor component (Table 2, Table 3).

All chipped-stone artifacts were made from obsidian. Ninety-one blade fragments were recovered; we also located a single projectile point. Although the Tuxtlas is a volcanic region, no local obsidian deposits have been identified; thus, all of this raw material was imported. Instrumental neutron activation analysis of obsidian blades along the Gulf Lowlands posits a strong correspondence between the color and source of raw material: clear/light gray–Pico de Orizaba; green–Pachuca; and black–Zaragoza (Heller and Stark 1998; Santley et al. 2001; Stark et al. 1992).

Blade production technology also provides a temporal index. Research suggests that platform grinding is associated with Postclassic Period obsidian production along the Gulf Lowlands (Heller 2001:164; Heller and Stark 1998; cf. Santley et al. 1986). Moreover, the association of ground platforms on clear (Orizaba) obsidian blades may be particularly linked to the latter half of the Postclassic period (e.g., Heller and Stark 1998:122; Stark et al. 1992:226).

The survey also recovered two metate fragments. In contrast to obsidian, basalt is locally abundant and both groundstone artifacts were apparently made from this local material.

Area A Artifacts:

Over 1250 artifacts were recovered from Area A. The overall distribution of this material reveals a central zone relatively free of debris with an increase in artifact density towards the southwestern edge of the complex (Figure 5). This concentration lies on the exterior edge of the patio complex and probably reflects maintenance of the interior plaza space with dumping along the outside perimeter.

Our initial assessment of the artifacts suggests that Area A was occupied during the latter portions of the Postclassic. For example, 27 obsidian blade fragments were recovered from the surface and 63% of these blade fragments are clear or light gray (Table 2). Moreover, 100% (7/7) of the blade platforms from Area A exhibit grinding (Table 3). By way of contrast, platform grinding was rarely present on the obsidian blades recovered during the Tuxtlas Regional Survey (e.g., Santley and Arnold 1996).

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The ceramics from Area A were also distinct from types previously identified in the Tuxtlas region (e.g., Pool 1995). Ceramic motifs include avian and geometric step-fret designs incised on the exteriors of orange or gray paste pottery, often with a brown slip or wash (Figure 6, shown above, and Figure 7, shown below). The paste of these pieces suggests local manufacture. Other decorations include incised circles on vessel interiors, covered with a red slip (Figure 8, shown below). Vessel forms consist of open bowls and restricted orifice jars. One sherd of Texcoco Molded, a Middle-to-Late Postclassic diagnostic, was also recovered (also see Area B Artifacts).

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Area B Artifacts:

In total, 106 collections were made from Area B. Despite having the most collections of the three areas, overall surface artifact densities are low in comparison to the rest of Isla Agaltepec (Figure 9). For example, only 56.6% of the collections from Area B contained ceramics, in comparison to values of 85.7% and 80.5% for Areas A and C, respectively (Table 1). Moreover, the Area B collections averaged only 5.6 sherds per unit (spu), compared to averages of 22.3 spu and 29.0 spu for Areas A and C, respectively.

There are some indications, however, that the comparatively lower densities within Area B are not necessarily representative of subsurface deposits. For example, collections made in the area of a tree fall in the northern zone of Area B generated some of the highest surface artifact densities encountered in the collections (17 sherds/sq m), indicating healthy pockets of sub-surface material. It would appear that, at least in some cases, the low surface artifact densities within Area B may be a function of ground cover, visibility, and terrain modifications.

Artifacts from Area B, more than any other portion of Isla Agaltepec, suggest a residential context. For example, both a metate fragment and undecorated spindle whorl were recovered from this area. Noteworthy is the fact that surface sherds in Area B are generally larger than those in the other two areas: Area B ceramics average 6.2 gr/sherd while ceramics from Areas A and C each average 5.3 gr/sherd (Table 1). This difference is on the order of 20% and suggests that artifacts in Area B may have been exposed to different formation processes in comparison to other portions of the island.

Although relatively sparse, the ceramic artifacts from Area B also suggest a later Postclassic occupation. In addition to a second Texcoco Molded sherd, pottery continues to exhibit the pattern of avian motifs on an orange or grey paste covered with a brown slip (Figure 10, shown above, and Figure 11, shown below). It is tempting, therefore, to associate the Area B occupation with the construction and use of the plaza complex in Area A.

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Ten obsidian blade fragments were recovered from Area B (Table 2). This number is noteworthy, given that almost twice as many collections were made in Area B compared to Area A, yet only one-third of the number of chipped stone artifacts were recovered. Unfortunately, comparative statistics are not particularly meaningful with counts this low. Interestingly, none of the obsidian blade fragments from Area B include platforms, while around 25% of the obsidian from the Area A and C collections exhibit platforms (Table 3). Whether this difference reflects simple sampling vagaries or supports a functional difference for Area B remains to be seen.

Area C Artifacts:

A total of 82 systematic surface collections were obtained from Area C; as noted above, just over 80% of these collections recovered pottery. Surface sherds were distributed across the entire Valenzuela Complex with highest densities occurring in two areas (Figure 12). First, frequencies that exceeded 100 spu were encountered on the east side of the enclosure, associated with the large C-1 pyramid. Comparable concentrations of materials were also recovered to the west, but in this case the collections came from just outside the complex.

Surface ceramics generally differed from those recovered in the two other areas of the island. For example, a large fragment of a red painted coarse orange jar was recovered (Figure 13, shown below). Comparable jars have been documented for Late Classic occupation in the region; in fact one example currently in the Tuxtlas Museum in Santiago, Tuxtla reportedly contained a burial. Valenzuela (1937, 1945) reported several burials in his explorations of Area C, but none of these were recovered from large jars.

Other examples of surface ceramics include an incised sherd made from a medium grey paste and a burnished jar, with a brown slip over an orange paste (Figure 14, shown below). Again, these sherds would fall comfortably within the known Late Classic ceramic repertoire recovered elsewhere in the Tuxtlas. They are currently attributed to the Postclassic based on the associated obsidian assemblage.

Fifty-five chipped-stone artifacts were recovered from Area C; a single obsidian projectile point and 54 obsidian blade fragments. Of these blade fragments, Area C contains comparable proportions of clear/gray material with Area A (61% vs. 63%), but the presence of green and black obsidian differs (Table 2). Area C has much less green obsidian compared to Area A (2% vs. 11%) and more black obsidian (37% vs. 26%). Moreover, just under 85% (11/13) of the platforms from Area C exhibit grinding, compared to the 100% value from Area A (Table 3). The lower amounts of green obsidian, the higher proportion of black obsidian, and the lower occurrence of platform grinding suggests that the Valenzuela Complex dates to an earlier portion of the Postclassic than Area A.

Previous fieldwork in the Tuxtlas encountered difficulty in identifying Postclassic, particularly Early Postclassic, remains (Santley and Arnold 1996). If the assessment of the Isla Agaltepec chronology is correct, then there might have been considerable carry over in the regional ceramic tradition from the Late Classic to the initial portions of the Postclassic. Thus, obsidian technology may provide a more temporally sensitive index than pottery, per se. Future research will help clarify this possibility.

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