Ancient urban alignment leads LiDAR investigation to new site

Ancient urban alignment leads LiDAR investigation to new site

By Alexis Bridges, Tanya Catignani y Ariel Texis Muñoz

At Teotihuacan the use of detailed satellite imagery and LiDAR technology has allowed for remote detection of archaeological features which are often impossible to see at ground level. It affirms that we can neither escape the legacy of the past nor the influences that it has on our present.

One of the goals of the Project Plaza of the Columns Complex this season has been to determine how much of the present-day Teotihuacan Valley was influenced by the ancient alignment of 15 degrees east of true north. Our team tracked this alignment by digitizing modern features in ArcGIS Online (Figure 1). Because the Avenue of the Dead is so central to the city, it seemed logical that nearby modern structures would be aligned in the same configuration, and areas farther away from the city center would less likely display this pattern. Our results abiding by the strictest of calculations revealed that more than 30% of the region does match this traditional alignment, even areas that are far away from the city center. One theory for this is that ancient structures, long crumbled and buried over the centuries since their initial construction, may have  influenced contemporary building and agricultural decisions by raising complications of digging and plowing around these archaeological features.

Figure 1: Satellite map of the Teotihuacan Valley with digitized modern features. Site TC-8 is located at the center-left.

One town in particular that drew our attention lies to the west of the city center (see Figure 1.) Nearly all of the town is aligned, resulting in a massive hotspot of digitized features on the map. However, the LiDAR and satellite maps did not reveal any obvious archaeological features in the area. After studying old archaeological reports, we found that this location had, indeed, been previously excavated. In the 1960s William T. Sanders discovered an apartment compound capable of housing hundreds of people at its peak occupation and was inhabited at least until the Colonial period (Figure 2). Although Sanders’ team identified this site as TC-8, the eighth site associated with the Teotihuacan Classic period, his site map lacked identifiable features that could have led us to the excavation site.

Figure 2: Site drawing of TC-8 by Sanders team (The Teotihuacan Valley Project).

Despite this, Sanders created a second map that charted the entire valley, fortunately safeguarding sites that may have disappeared over time. A rough location of the site was found by georeferencing what streets and towns still existed. From there, a rock alignment could be seen on the LiDAR map as well as very, very slight mound formations that closely matched with the ones identified on Sanders’ map (Figure 3).

Figure 3: LiDAR digital elevation map (DEM) showing the mounds at TC-8.

Preliminary ground truthing has yielded promising results of pottery sherds and shell fragments  ̶  an unusual find for an inland area. Using a similar process, another site in the southwest known as TC-21 was also located with similar finds of ceramic sherds. Although these preliminary results are not confirmation, they do indicate that our locations may be these previously forgotten Sanders’ sites.            

This experience highlights the power of combining modern technology with historic data. Technology without the analog aspects of archaeology cannot show us everything, and relying entirely on technology will create a loss of data. The re-discovery of TC-8 and TC-21 only shows that archaeology is, and will likely remain, a historical science at its foundation.



Recent Discoveries at Teotihuacan: Excavations at the Plaza of the Columns

Free admission and stream online

As part of a circuit of conferences called “Archaeology Today” (coordinated by Dr. Leonardo López Luján), Dr. Saburo Sugiyama and Dr. Nawa Sugiyama, co-directors of the Project Plaza of the Columns Complex, will present an interesting lecture on the most recent discoveries at Teotihuacan made by their project.

Multiple aspects of Teotihuacan, such as urban planning, new LiDAR maps of the Teotihuacan Valley, the arrival of Maya elites, and the sacrifice of animals, will be revealed to the general public.

Do not miss this opportunity to attend the Colegio Nacional next Wednesday, June 12th, at 6pm. If you can’t make it in person, check out to stream online.

And behind the archaeologists… our fieldworkers

And behind the archaeologists… our fieldworkers

by Adriana Sánchez

It has been an intense week with the conclusion of the third field season (2017) of the PPCC. This includes putting the final touches on all pending fieldwork tasks: the last photo taken, the final line drawn, and the closing word of descriptions written in the notebook.

We have just three days left for filling in the last four open excavation areas. The first of them extends over an area of 12 meters long by 3 meters wide and reaches depths between 2 to 4 meters. The second area is not that wide but is certainly large and complex; it is a tunnel that runs over 10 meters long, 1 meter wide, and 1.5 meters high. The third one is located on one of the highest structures of the complex covering an area of approximately 9 meters long, 6 meters wide, and 3 meters deep. The last area revisits a tunnel previously excavated during the first fieldwork season in 2015 and continues to provide several interesting finds.

Upon finishing the last field details and closing out the season, the adrenaline runs high with a mixture of stress, anxiety, and emotions. All excavated areas must be cleaned and perfectly covered in backfill.

In order to accomplish these monumental tasks, we rely on local fieldworkers from neighboring communities near the “Zona de Monumentos Arqueológicos de Teotihuacan” (Teotihuacan Archaeological Monuments Area, ZMAT). These individuals are usually young men who recently turned 18 years old (legal working age in Mexico) and thus experience their first job with the project or, on the contrary, are mature men who each have more than 10 years of experience working for diverse archaeological research projects in the ZMAT.

These are the people who do all the hard and labor-intensive work: lifting heavy buckets filled with earth from excavation area to sifting station, carrying heavy stones out of excavation areas, finding out ways to protect excavations from rain by maneuvering a makeshift awning, among many others tasks. Although archaeologists lead the fieldwork and its activities, we acknowledge the hard and important labor our fieldworkers do to support us and the PPCC.

Often times, the fieldworkers have to endure when an archaeologist is in a bad mood during stressful situations due to lack of time particularly at the end of the field season. Despite this, they are supportive and encourage us to continue working on “that what we call archaeology.”

Not everyone can be a fieldworker in an archaeological project as this job demands a balance of finesse, precision, and strength. Finding the right combination and stamina may ultimately decide whether one returns for the next field season. However, we gladly welcome back most familiar faces who possess these characteristics and look forward to working together again out in the field, right until the inevitable stressful end of the season.

THANK YOU TO ALL who supported our PPCC team during this third field season! Muchas gracias!

2018 SAA Conference = A Success!

2018 SAA Conference = A Success!

Hello, everyone! We had an amazing turnout at the SAA’s 83rd Annual Meeting in Washington, DC, and had a wonderful time sharing with you just a snippet of our multidisciplinary work at the Plaza of the Columns Complex. On behalf of the PPCC team – past, present, and future – thank you so much for all the support! We resume excavations this summer and hope to continue exploring and sharing our findings straight to you.

Society for American Archaeology 83rd Conference

Society for American Archaeology 83rd Conference

Come join us at the Society for American Archaeology’s 2018 conference in Washington, D.C., on April 14th from 1:00 PM – 4:00 PM in Washington Room 1. The team will be hosting a symposium on Project Plaza of the Columns Complex: New Investigation of a Civic-Administrative Complex at the Heart of Teotihuacan, Mexico. Come see what we’ve discovered so far, directly from our very own directors, archaeologists, and specialists. We’ll be presenting on various subjects, including LiDAR mapping, murals, human caches, ceramics, archaeomagnetism, and so much more. See you all there!

Teotihuacan: City of Water, City of Fire

Teotihuacan: City of Water, City of Fire

Interested in seeing Teotihuacan artifacts? Come visit the new exhibition Teotihuacan: City of Water, City of Fire at the de Young Museum in San Francisco, California (September 30, 2017 – February 11, 2018). Can’t make it, or simply want to learn more? Check out the catalog for this exhibition where you can read chapters written by our very own PPCC co-directors.

Welcome to the 2017 Season

Welcome to the 2017 Season

We are very happy to announce that we have started working on the exploration of the Plaza of the Columns. So far, we are a team of 20 archaeologists – 13 are out in the field excavating different interest areas of the Complex, 2 are performing surface surveys of the Teotihuacan valley, and 5 others have dedicated labwork analyzing botanical and skeletal remains of multiple species recovered in previous excavation seasons. This first half of the season began on June 12th and will conclude on the last day of July, and the second half of the season will begin in early August and will finish by mid-October.

All of us who make up this team commit to our archaeological research with the aim to achieve the best results possible, and in doing so, we invite the public to follow along with our progress in uncovering this Mesoamerican society.

Virtual 3D Animal Bone Models

Virtual 3D Animal Bone Models

Zooarchaeology is a field within archaeology that seeks to answer questions about past human occupation and their environment through the study of animal remains1. In practice, this means that a zooarchaeologist must be an expert in identifying animal bones. However, animals come in diverse shapes and sizes. How can someone develop expertise in such a broad field?

Having a comparative reference collection is key for understanding and formulating distinct patterns among differing species. And this is where I come in. I have just finished a project that helps lay the foundation for zooarchaeology students to build their proficiency in bone identification. Over the last four months, I have created a series of virtual three-dimensional models of deer bones. Everything from a deer’s cranium to the phalanx (or toe bone) is captured in this digital collection. Below you can explore some examples of these models:



So, how do you even start to create a 3D model? Well, it starts with taking dozens of photos of each bone element. I then loaded the photos into a program called Agisoft’s Photoscan which “stitched” them together; by taking multiple photos from different angles and views, the program was able to compile these series of two-dimensional images and transform them into virtual 3D models. After the deer bones were modeled, I uploaded them onto Sketchfab, a website that allows users to display, embed, and share 3D models online. Sketchfab is particularly helpful for this project because it allows students to view the models on smartphones, tablets, and computers alike. It also has the feature to place annotations within each model, as evidenced by the standard measurements and points included on each bone.

I will find out this summer how these models work in practice, for several students from George Mason University (GMU) are flying to Mexico to examine animal remains in the field as part of the Project Plaza of the Columns Complex (PPCC). I spoke with one of the students, Leila Martinez, about how she has prepared for this challenging task of traveling and working without a deer comparative and how she thinks 3D models might help her this summer.

According to Leila, learning zooarchaeology requires extensive hands-on study of bones. With the absence of physical bones in hand, students often rely on animal bone manuals, though these often contain hand-drawn images from few static views. She believes that 3D models may make bone identification easier by letting students interact with realistic images. While 3D technology will never be able to replace the direct tactile experience of working with real bone, in time, these 3D virtual reconstructions could rival traditional reference books. After all, books are bulky and often times expensive, and a digital skeletal collection can be easily transported and manipulated all by the swipe or click of a finger.

Students coming to Teotihuacan for zooarchaeological fieldwork can be an exciting and perhaps a little apprehensive experience, especially when one doesn’t know what to expect when joining the PPCC team for the first time. Is there a skeletal reference collection I can use? How complete is it? In what state are the bones I will be analyzing? Several GMU students like Leila and me already have firsthand experience handling bone with cleaning and labeling the many (or shall I say thousands of) animal remains in our Archaeological Sciences lab. Although real world archaeological assemblages are surely more complex with fragmented, commingled, and/or missing bones, I know the hard work I put into preparing these models of complete bones will help zooarchaeologists to confidently identify the specimens they encounter. Creating virtual 3D reference models is a time-consuming endeavor, but in the end I expect these easily transportable, full of detail, and user-friendly products will play a much larger role out in the field than anticipated.



1. Steele, T. E. 2015. The Contributions of Animal Bones from Archaeological Sites: The Past and Future of Zooarchaeology. Journal of Archaeological Science 56: 168–176.

What can be learned through pottery analysis?

What can be learned through pottery analysis?

The case of candeleros

by Yolanda Peláez Castellanos

The potters who made the ceramic pieces recovered in archaeological excavations gave them different shapes depending on the function they would have (e.g., pots and bowls were used in the preparation and consumption of food). A very distinct form that corresponds almost exclusively to Teotihuacan can be seen in the figure below; these vessels have been found in various foreign sites, and each have been attributed to Teotihuacan presence or influence.

Candlesticks from distinct phases (photograph by Fredy Álvarez)

These vessels are small and can have one (4x5x4cm) or two (5x8x5cm) cylindrical chambers, the latter usually having lateral perforations. In the Colony Period they were called “candlesticks” because the indigenous people reused them to support candles (Ceballos 1992: 205-206), but these did not exist when the city of Teotihuacan was inhabited.

The analysis of the candlesticks gives us information about them (Peláez 2018):


– When examining the pieces, you can see the ” that was used to decorate them (e.g., punching, incision, fingerprints).

– More time was spent in the production of some pieces (e.g., it takes longer to manufacture a candlestick with a polished lip like those of the Xolalpan phase than one with fingerprints like those of the Metepec phase).

– The method of making and decorating them has changed over time. Based on physical attributes, they were classified into three phases considering the parameters of an already established chronology (Rattray 2001). Accordingly, this indicated that the production of candlesticks lasted for a period of approximately 400 years (250-650 AD). (See Ceramic Analysis, Relative Chronology)


Some visible features give us clues about the use of the candlesticks:

– The dark traces in the chambers indicate that something was burned inside them.

– Charred organic remains were found inside some of the tested chambers.

Candlesticks from distinct phases (photograph by Fredy Álvarez)

In order to determine the substances that these artifacts may have contained, their chemical residues were analyzed. These residues are stored in superficial pores where liquid or semi-liquid substances might have spilled. If this action (of use) was repeated or if a large amount of matter was deposited, some components present in these solutions can be identified (i.e., phosphates, carbonates, proteins, fatty acids, carbohydrates, and pH can also be measured) through tests called spot-tests (Barba et al. 2008: 721; Barba et al. 2014: 202-204). This type of methodology is also used for soil chemistry analysis (Barba et al. 1991).

Not all the candlesticks demonstrated a discernible amount of residue, but the combination of components that were identified was interpreted as moderate combustion of cellulose, presence of substances of animal origin, and combustion of resins (Peláez 2018). This is consistent with the results of other investigations (Ortiz 2006).


The location where the materials were found in excavations sometimes corresponds to the place where they were discarded and not necessarily where they were used, although it is feasible that they were used in the vicinity and in various locations in Teotihuacan. In large part, the candlesticks have been found associated with domestic spaces.

Most of the analyzed PPC candlesticks (77%) came from Front C. It was originally hypothesized that this area was domestic, although so far only rooms have been found west of Mound 25Z and north of Structure 26A. The presence of candlesticks supports the idea that this area could have been residential.

Excavation units with the presence of candlesticks and percentage of sample present per front

Excavation units with the presence of candlesticks and percentage of sample present per front(Map data ©PPC, modified by Yolanda Peláez)


Barba, Luis, Roberto Rodríguez, y José Luis Córdova

1991      Manual de técnicas microquímicas de campo para la arqueología. Instituto de Investigaciones Antropológicas, Universidad Nacional Autónoma de México, México, D.F.

Barba, Luis

2008       Los residuos químicos en cerámica. Indicadores arqueológicos para entender el procesamiento de alimentos y el uso de recipientes. In Quaderni di Thule VIII. Atti del XXX Convegno Internazionale di Americanistica, pp. 721-728. Centro Studi Americanistici Circolo Amerindiano, Perugia.

Barba Luis, Agustín Ortiz y Alessandra Pecci

2014       Los residuos químicos. Indicadores arqueológicos para entender la producción, preparación, consumo y almacenamiento de alimentos en Mesoamérica. Anales de Antropología 48(1):201-239.

Ceballos Novelo, Roque

1922      Candeleros. En La población del valle de Teotihuacan, Vol. 1, edited by Manuel Gamio, pp. 205-212. Secretaría de Agricultura y Fomento, Dirección de Antropología, México, D.F.

Rattray, Evelyn

2001      Teotihuacan: cerámica, cronología y tendencias culturales. Instituto Nacional de Antropología e Historia and University of Pittsburgh, México D.F.

Ortiz, Nidia

2006      El candelero: estudio comparativo sobre su función en Teotihuacan durante el Clásico, Epiclásico y Posclásico Temprano. Tesis inédita de licenciatura en Arqueología, Escuela Nacional de Antropología e Historia, México, D.F.

Peláez Castellanos, Yolanda

2018       Los candeleros del Complejo Plaza de las Columnas, Teotihuacan. Tesis inédita de licenciatura en Arqueología, Universidad de las Américas, Puebla, Cholula, Puebla.

The Elements of a Paleodiet: How Isotope Analysis Help Archaeologists in the Lab

The Elements of a Paleodiet: How Isotope Analysis Help Archaeologists in the Lab

by Esther Aguayo

Food is an important part of our lives, yet it is a difficult thing to see in the archaeological record. Usually archaeologists rummage through ancient trash piles to look for animal bones and residues in pots to find out what people ate. However, there is another tool that archaeologists use that can tell us more about what people and animals consumed called stable isotope analysis. This methodology helps archaeologists understand the chemical make-up of human and animal bones to reveal information regarding diet, social organization, and human-animal interactions. At the Archaeological Sciences Lab at George Mason University, I help prepare bones in order to extract that information.

All living organisms are comprised of molecules that they have absorbed or eaten throughout their lives. Bones, teeth, and even hair molecules can tell archaeologists a lot about an organism’s life history and environment. These molecules, referred to as stable isotopes, and their composition can vary depending on the environment of the organism. Factors such as temperature, altitude, nutrition, and humidity affect isotopic composition and will be reflected in the tissues we look at. There are several isotopes that can be analyzed such as carbon, oxygen, nitrogen, and strontium. 

Carbon is most familiar as the lead in our pencils and what we breathe out in carbon dioxide, but carbon also relates to the way plants obtain energy or photosynthesis. C3 and C4 cycles are the most common photosynthetic pathways a plant can use and can be determined from bones of an animal or person who ate plants. Since photosynthesis varies among plants, archaeologists can reconstruct what people and animals were eating, where they lived (based off where the plants grew), and how their diet changed over time. This is the information that can be deduced from carbon alone. It is important to collect the information stable isotope analysis provides. So, how do archaeologists conduct isotope analyses?

An archaeological deer bone with a piece removed for isotope analysis.

In the Archaeological Sciences Lab I help prepare the bones to extract the isotopic information we need. The bones from the Project Plaza of the Columns Complex (PPCC) are cleaned after excavation. Then, the bones are analyzed, identified to species, photographed, and documented for further reference. It is important to document the bones well because isotope analysis is a destructive process. First, I make sure the bones are cleaned completely. Using a hand rotary tool, I thoroughly clean off any excess dirt and build-up on and inside the bone. I also use the rotary tool to remove a part of the bone that will be used for the isotopic analysis. Then, I wash the bones in a sonic bath which uses high frequency sound waves to remove any remaining dirt that cannot be removed by hand.

Isotope samples ready to be soaked overnight.

After letting the bones dry overnight, I use an agate mortar and pestle to crush the bones into a fine powder. I weigh each sample and transfer them to tubes so they may soak overnight in a chemical solution to begin the removal of organic components. Then, the samples are rinsed in ultrapure water, and an acid solution is used to completely remove all organics in the sample. Once weighed a final time, the sample is ready for the mass spectrometer at the Smithsonian Museum Conservation Institute. The mass spectrometer is able to measure isotopic variations in a sample. It is through those variations that archaeologists can gain insight on the diet of the individual and the ecosystem they lived in.

Adding a chemical solution to remove organic material from the bone powder.

At first glance, isotope analysis is intimidating to someone with little experience with heavy machinery and chemicals. However, since working at the Archaeological Sciences Lab, I have greatly enjoyed my time learning about isotopes and the many questions about ancient life that can be answered through this process. Stable isotopes open a new window into ancient life that tell archaeologists about more than just food consumption. At the PPCC, isotope analysis has helped investigators find out more about animal management and how it had affected social structure in ancient Teotihuacan. The potential use of isotope analysis is quite vast, and archaeologists still have much more to discover using this fascinating methodology.


  1. France, Christine A.M., Douglas W. Owsley, and Lee-Ann C. Hayek. “Stable Isotope Indicators of Provenance and Demographics in 18th and 19th Century North Americans.” Journal of Archaeological Science 42 (2014).
  2. Schwarcz, H.P, M.J. Schoeninger. “Stable Isotopes of Carbon and Nitrogen as Tracers for Paleo-diet Reconstruction.” In Handbook of Environmental Isotope Geochemistry, by M. Bakaran, 725-742.
  3. Sugiyama, Nawa, A.D. Somerville, M.J. Schoeninger. “Stable Isotopes and Zooarchaeology at Teotihuacan, Mexico Reveal Earliest Evidence of Wild Carnivore Management in Mesoamerica.” Plos One 10, no. 9 (2015).
  4. Sugiyama, Nawa, William L. Fash, and Christine A.M. France. “Jaguar and Puma Captivity and Trade among the Maya: Stable Isotope Data from Copan, Honduras.” Plos One 13, no. 9 (2018).
  5. White, Christine D. “Stable Isotope and the Human-Animal Interface in Maya Biosocial and Environmental Systems.” Archaeofauna 13 (2004). 183-198.
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