Late Classic and Epiclassic Obsidian at Santa Cruz Atizapan, Toluca Valley, México

Obsidian Use

A 20x hand lens was used to identify wear patterns on the edges and surfaces of nearly 9,000 objects. The extent to which obsidian objects were used, re-sharpened and reused can provide us with information regarding the value or scarcity of the material and their importance for accomplishing daily tasks. In this assemblage it might also indicate a specialization of use adapted to lacustrine environments. Over 37% of the obsidian exhibited intensive surface modifications indicative of use. This is a very conservative percentage because we only recorded use if it was distinctly visible on an object and it could not be attributed to accidental breakage or post-depositional processes. In a sample of 3,097 utilized flake tool and prismatic blade artifacts, 55% were used on more than two-thirds of their existing edge lengths. An additional 28% of this sample displayed use wear scars on more than one-third of their edges present. It thus appears that great efforts were made to fully utilize the imported obsidian material. The variability in hafted biface forms noted earlier may further reflect a conscientious effort to rework and reuse bifaces that shattered with use. Blades of projectile points are often reworked and reused as long as the hafting element remains intact.

The excavated islands 20 and 13 of the Santa Cruz Atizapan site represent public and domestic areas, respectively. Despite this, the initial analysis of the obsidian suggests that it was not used very differently in either context. It appears that obsidian was used almost exclusively to complete basic functional tasks in both public and domestic contexts. Artifacts often associated with ritual or high status are lacking in the assemblage. Aside from the needles that may have been used for blood-letting and the crudely made eccentrics which may have some ritual significance (Stocker and Spence 1973) all of the remaining artifacts served basic cutting, scraping and perforating tasks. This does not however, preclude the use of simple tools such as prismatic blades to perform ritual, funerary or other non-secular activities. At the Santa Cruz Atizapan site obsidian objects may simply not have been specifically modified to perform these tasks. It is also uncertain whether specialized activity areas are indicated by the distribution of obsidian. Presently it does not appear that specialized tasks utilizing obsidian were limited to certain parts of either island.

What then does this preliminary data suggest about obsidian use at the Santa Cruz Atizapan site? The intensity of use wear macroscopically visible on many prismatic blades demonstrates a great effort to use obsidian to its fullest potential. This may have become more imperative during the transition to the Epiclassic period when obsidian was no longer imported into the valley via the Teotihuacán network. Toluca Valley residents had to locate an alternative source for their obsidian and establish a trade network that would provide them with finished prismatic blades, bifaces, etc. It is therefore not surprising to find that highly crafted obsidian objects were not recovered from Mound 20, where a continual series of superimposed public structures were constructed with numerous accompanying ritual offerings. The need to conserve obsidian material is further highlighted by the absence of alternative lithic materials which could have been used instead of obsidian.

The recovered faunal materials and richness of the lacustrine zone undoubtedly establish that the lake region was primary in the lives of the Santa Cruz Atizapan people. Evidence for hunting, gathering and fishing is represented in the material culture. Local lithic strategies must therefore be representative of those tasks, as they were adapted for use in a lacustrine zone. It does not appear that very many tools, aside from hafted bifaces, were specialized to perform specific tasks. Instead a more generalist approach was implemented. It would have been more efficient to conserve materials by adapting the tool to the task at hand. This strategy only succeeds if you are able to carry objects that could easily be modified for use. Prismatic blades, (85% of the assemblage) were perhaps the easiest functional cutting tool to carry with you. It could be modified for cutting, scraping, piercing in very little time by a non-specialist.

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