Teotihuacan Researcher Profile: David Walton

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photo of David Walton at analysis table

David Walton at his analysis table.

September 3, 2015

One of the many benefits of the ASU archaeological research facility in San Juan Teotihuacan is that it enables comparative laboratory projects.

David Walton, a Ph.D. candidate at Boston University, spent the summer of 2015 analyzing stone tool collections from excavations at six different archaeological sites in central Mexico.

The sites were excavated by four major research projects funded by the National Science Foundation and other sources. These projects were carried out by archaeologists from Boston University, UCLA and Pennsylvania State University between 1984 and the present.

Walton's project would simply not have been possible if the artifacts had not been stored and curated at this facility.

Walton received a Doctoral Dissertation Improvement Award from the National Science Foundation to investigate how members of ancient households made and used stone tools of obsidian.

The first component focuses on the ways different production strategies were used to produce diverse tool forms for specific functions.

Household tools are important to archaeologists because they reveal patterns of technological experimentation and invention; the forms of exchange in nearby marketplaces or long distance trade; and even ritual behaviors including bloodletting.

Walton's second component studies the ways that ancient people used obsidian tools. This research requires a special high-power binocular microscope.

photo of Walton's microscope

In the photo to the left, the microscope is fitted with a camera for close-up photos. The microscope reveals traces of the specific activities the tools were used for. Some activities leave characteristic scratches or marks on tools, while others leave tiny residues that still adhere to the tool after a thousand years or more.

He has studied one of the largest samples of stone tools subjected to high-power microscopic use-wear analysis to date in Mesoamerican archaeology.

photo of red residue from obsidian bloodletter

Red residue identified on an obsidian bloodletter. This will be tested with chemical analysis.

As of late July, Walton has made several notable finds. For example, he found a blood-like residue on obsidian blades that were used as ritual bloodletters from the sites of La Laguna and Teotihuacan. These residues can now be tested chemically to see whether the red residue is really human blood, animal blood or something else.

He has also identified spatial differences in the types of craft production at the Tlajinga 17 and 18 residences near the southern urban edge of Teotihuacan.And for a more recent period, his analysis has illuminated the large scale of production of obsidian bifacial tools at Cihuatecpan, a rural Aztec village not far from Teotihuacan.

photo of Walton practicing obsidian knapping

David Walton practicing his obsidian knapping.

After the conclusion of his project, Walton plans to keep his microscope equipment stored at the ASU laboratory in order to help future researchers conduct more scientific analyses on the artifact collections stored here. This gesture is fitting with the spirit of collaboration that helps to bring archaeologists from universities in the U.S. and Mexico year round to this important facility.

When Walton is not looking through his microscope, you might find him out back honing his skills in making obsidian tools. This kind of “experimental archaeology” not only helps archaeologists reconstruct ancient technologies, but it is also fun.