Ancient Aztalan: A Diverse Community

Research Summary

Ancient Aztalan is a prehistoric Native American village in southern Wisconsin that was occupied between 800-1000 years ago. Archaeological evidence suggests that Aztalan was an ethnically diverse community - some residents were local to the area, but others were newcomers who brought their exotic beliefs, practices, and ways of living with them. Who were these diverse peoples? How did they combine their different beliefs and practices to form a joint community? Did they get along, or did their differences ultimately lead to Aztalan’s abandonment? Despite nearly 100 years of investigations at Aztalan, these questions remain unanswered.

This project is designed to locate and excavate ancient domestic structures at Aztalan and integrate those findings with the unpublished architectural data generated in the 1960s and earlier. Aztalan's houses were built in a variety of forms and with different construction techniques, which may reflect Aztalan’s diverse ethnic groups. Understanding the details of these houses and their contents will be helpful in understanding how the people of Aztalan cooperated in daily life. Additionally, architectural variability in Aztalan's palisade walls also has the potential to reveal information about the site's diverse occupants. The project utilize ground penetrating radar and magnetometry to detect archaeological features under the ground surface.

Community Formation - Migration, Coalescence, and Diversity

Investigations into the consequences of Mississippian migration to Aztalan have tended to suggest passive “Mississippianization” of the Late Woodland peoples. The popular “Mississippianization” concept resembles other models of asymmetrical culture change based on acculturation and colonization. The possibility that Mississippians and Late Woodland peoples jointly participated in their community has only been recently explored (Zych 2013).

Data from the northwest and northeast mounds and site-wide material assemblages are consistent with the interpretation that Aztalan was a frontier of diverse peoples and multi-directional influences. From this perspective, the interactions at Aztalan are not conceptualized in terms of migrants from Cahokia “Mississippianizing” local Late Woodland groups in the hinterlands as has often been the case for Aztalan and similar sites in the region. Rather, this perspective provides an alternative non-Cahokia-centric model – that Mississippian migrants at Aztalan were not hegemonically dominant, but were influenced by the Late Woodland peoples with whom they interacted in daily life. This differs from many discussions of interaction that are framed around colonialism, acculturation, core-periphery relationships, and dominant-subordinate dichotomies. Overall, viewing Aztalan within a frontiers framework gives greater agency to indigenous peoples by de-emphasizing the immutability of socially-complex groups. The proposed research explores multi-directional interaction at Aztalan by examining how ethnic identity was expressed in domestic household and palisade wall architecture.

Ancient Perishable Architecture

Domestic structures in particular have great potential to communicate information about their builders and residents because outwardly visible elements like structure shape, entrance, and exterior decoration are openly visible to the whole community. In multi-ethnic contexts, public elements of structures are more likely to be manipulated than low-visibility “hidden” attributes that may be intentionally kept private or otherwise may not be visible from outside a finished structure (e.g., internal organization and construction methods and materials). The public/external and private/hidden aspects of a structure can also reflect different, overlapping identities of a family simultaneously.

Mississippian structures in the Midwest are typically rectangular, semi-subterranean, and constructed using wall-trenches. Wall-trench construction involves erecting posts or possibly pre-fabricated walls into previously-dug linear trenches that are visible archaeologically as linear stains in the soil. In contrast, Late Woodland structures in the Midwest vary in shape - often within the same site component – and include rectangular, ovoid, circular, and irregular forms. Many have extended entryways of varying lengths that form a “keyhole” shape. They are typically semi-subterranean and most exhibit “single-set post” construction, in which posts or poles are erected into individually-prepared holes. Some are defined only by a basin stain. Aztalan’s structures exhibit a variety of forms and construction technologies, but typical wall-trench Mississippian and single-set post Late Woodland structures are less common than hybrid configurations.

Palisade Walls

Monumental works that define the layout, boundaries, and appearance of sedentary communities, such as Mississippian palisade walls and platform mounds, provide ways for diverse peoples to participate in the literal, physical formation of their shared community. This is also a way for migrants to establish enduring, common ties to the physical place alongside local peoples. A shared sense of community identity would facilitate successful integration in other aspects of daily life, leading to inter-group cooperation and blending of daily practices and material culture. At Aztalan, successful integration and shared participation in physically formation of the community should be evident in blended architectural traditions in the palisade walls rather than evidence that they were designed and constructed by one ethnic group.

Like with domestic architecture, palisade walls also have regionally and culturally patterned differences. Non-Mississippian palisades across the upper Midwest and Northeast were generally lightweight screens constructed with small posts (average less than 15 cm diameter), lacked bastions, and enclosed a high density community. In contrast, Mississippian palisades in the southeast and Midwest were built from larger diameter posts (average 15-25 cm diameter and larger), were studded with regularly spaced bastions, featured well-designed defensive entrances, and enclosed residential, extensive public, and ritual spaces. The patterned differences between Late Woodland and Mississippian palisades and domestic structures make them useful diagnostic indicators in multi-ethnic contexts like Aztalan.

This Week at Aztalan - 2016 Fieldwork Blog

Five Myths of Aztalan

There are a lot of myths floating around the “legendary Lake Mills” and many of them revolve around the Native American site of Aztalan. So, we have made a list of some of the most common myths of ancient Aztalan.

Myths of Aztalan
  1. Aztalan was built by peoples of the Aztec empire
  2. The people who inhabited Aztalan were cannibals
  3. All of the mounds were used for burials
  4. The walls were set up as a defensive border
  5. Mississippian immigrants ruled the local Late Woodland population

As scientists and archaeologists, we question these myths. Many decades of investigation at the site have demonstrated that they first two of these myths are wholly false. Aztalan was built and settled by Native Americans, some were migrants from modern-day Illinois (archaeologists refer to these peoples as Mississippians) and some who already lived in the area (archaeologists call these local people Late Woodland), and there is no evidence that they practiced any form of cannibalism. Excavations at the site many decades ago demonstrated that some of the mounds were not used for burial, while others were. The last two myths cannot be discredited without further investigation, and remind us that it is important to ask what we actually know about the site and its residents based on cultural artifacts like pottery, animal bones and plant remains, stone tools, and residential architecture.

During our first week at Aztalan, our hard-working team has learned many skills essential to becoming a successful archaeologist. We have learned how to remove soil with a shovel in thin and even layers. This process is called shovel skimming.

We have also learned how to use a trowel to clean the walls and floor of our test units to reveal differences in soil color. These techniques may sound easy, but they can be difficult to execute at times. Roots, the texture of the soil, and the moisture content all affect how easy it is to keep the walls and floor of the test pit even and smooth. A good pit should have 90 degree angles where the walls meet the floors. But, it is difficult to maintain vertical walls within the test unit, which is crucial to see different layers in the profiles clearly.

These techniques allow us to notice important details in the soil that give us clues to understanding how the Mississippian and Late Woodland people arranged and constructed the site. Our goal is to use this information to better grasp what everyday life was like for the people of Aztalan.

Our team has been screening soil to recover small artifacts like broken pieces of pottery, small flakes of stone, and other materials like charred nutshell and small animal bones.

week 1 photo week 1 photo week 1 photo

The first week of excavations here at Aztalan has gone well, and we are very excited to see what the next layer of soil has hidden in its depths. Stay tuned for our next week summary of our work at Aztalan to see what we can learn about this site and its people, or better yet come visit us and see for yourself!

Understanding the Soil

After a Memorial Day weekend we were back at work with our excavations. Everyone returned to work on Tuesday, but rain caused us to have to pack up early and we, all covered in dirt, headed to the Hoard Historical Museum in Ft. Atkinson to see their Mysteries of the Mounds exhibit. The exhibit consisted of a very informative video on the mound building cultures of the Midwest, hundreds of artifacts to view, and a diorama of a Late Woodland camp. The whole museum, and especially this exhibit, was very well done and everyone had a great time exploring. We were back to work on Wednesday and by Friday all three test pits were either at or below the base of the plow zone between 50 and 60 centimeters deep.

By the end of the week every test pit (TP) found interesting artifacts and changes in soil color and consistency. TP7 and TP8 began to see oily, dark soil mottling around 52cm-56cm. This is consistent with the features that were found immediately to the west in TP6 last summer. TP7 and TP8’s features include the possible postmolds of a palisade wall. TP9 began to see dark mottling around 49cm-50cm in depth which may indicate an old excavation unit from the 1920s. TP9 also showed plow scars that date back to the early to mid 1800s and sterile soil, soil without the evidence of human activity, both showing up around 52cm. Artifacts found throughout all pits include more pieces of pottery, bone, stone flakes, and charcoal. TP7 found a small piece of cord impressed pottery while TP9 found a small piece of animal bone.

A plow zone (PZ) is a section of soil that has been disturbed by farming and plow tools. Any artifacts found here are not in any sort of context and, while interesting, can not always tell us much about what time frame they came from or even what area of a site they came from, as plows move around large amounts of dirt. Aztalan was one of the first farmed sites in Jefferson county and had a long history of farming before it became a park and therefore has an abnormally deep PZ. Now that we have reached the end of the plow zones we are starting to see soil color changes. In the plow zone the soil was a homogenous brown color and now below the plow zone there is a large amount of mottling of lighter and darker soils, gray soils, greasy black areas, and areas with gravelly soil.

These changes in the soil must be carefully observed, noted, and mapped because they can represent things called features. A feature is something that contains evidence of human activity and can be things like hearths, post molds, wall trenches, trash pits, and house basins. Dr. Schroeder carefully examined the features in the pit floors to hypothesize what they may represent. One of the most intriguing of these features possibly represents large diameter post molds from a wall or a bastion and can be seen in TP7 and line up with the same shapes in TP8. These post molds are significant because one of the big questions of Aztalan is whether all the walls were standing at the time. These post molds intrude into other features and potentially lend evidence to the hypothesis that not all the walls at the site were standing at the same points in time. The features in TP9 possibly represent an old excavation and possible trash pits which contrast in color and texture with the sterile soil.

This week at Aztalan was very successful because the changes in soil texture and color represent features that may solve many of the questions we pose about the daily life of the Mississippian and Late Woodland culture. We are all excited to continue excavating and find a possible explanation to the uses and types of the features and the artifacts that we have found.

Post Molds, Post Molds, Post Molds

This week at Aztalan yielded some of the greatest excitement yet! Large post molds, too many features to count, potsherds, lithics, and animal bones galore. To wrap it all up we had successful public days on Friday and Saturday (the 10th and 11th of June). The increase in artifact and ecofact density can be attributed to our depth in all test pits, where we have gone below the plow zone and into the features of thousand-year-old walls, and structures. As exciting as this is, it’s not all fun and games or just digging into the ground to find neat artifacts: Archaeology is a science and a deliberate and careful one at that. As budding professional archaeologists, we take care, time and consideration to almost every bit of soil we extract from our pits.

It is a common misconception that archaeologists are just digging in the ground “looking for gold;” the reality is that archaeologists are meticulous and passionate stewards of cultural history who are bound to the scientific method. As scientists, we develop hypotheses about what features may be and test these hypotheses by carefully mapping, excavating, and evaluating the findings. Often we are confronted with situations that challenge these hypotheses and require us to reevaluate what we previously thought. One such example of this is in test pits 7 & 8. One of our predominant features is evident as a grey soil, possibly a house basin, however we noticed circular spots of dark brown soil intrusive into the grey soil and arranged in a linear fashion on a north-south line through both test pits. We have hypothesized that this is a stockade wall, and further excavation will allow us to determine if these circular “stains” persist with depth, helping confirm our suggestion that each of the “stains” is a postmold from a stockade wall. Each feature and level in our pits is wrapped up by extensive paperwork documenting orientation, density of artifacts and any other indications that may be pertinent to supporting or undermining our hypotheses. Record keeping is the most important part of our work as archaeologists because we destroy our “experimental” data in the field as we dig. This process of developing, testing, and documenting hypotheses is a crucial component of conducting archaeological research.

Participating in public outreach, as we did this week during our two public days, is one of the many obligations of conducting archaeological research. It provides not only an educational and enriching experience to all visitors but also exposes people to a unique breadth of science that is founded in the scientific method and fueled by the desire for discovery. Beyond education, archaeological outreach provides an opportunity to share and connect people with ancient cultures that lived here so many years ago. The ability to share this history with the scientific community, schoolchildren, and the general public allows us to correct the misunderstandings they might have about our objectives but also about the ancient cultures we are studying. It is our role as scientists and archaeologists to communicate, to the best of our abilities, the empirical knowledge about the peoples and cultures we study. Most importantly, archaeology teaches us all to never stop asking questions, to always challenge the conventional, and to never be afraid of getting your hands dirty.

From the Land to the Lab

Our last week of excavation brought us face to face with one of the challenges of fieldwork: adapting to the ecological environment. As archaeologists, we must not only be well-informed in areas of history, geoscience, anthropology, biology, and material culture studies, but we must also be quick thinkers when faced with unexpected obstacles in the field. Being at the mercy of natural forces is an understood aspect of the science of archaeology, which is so often conducted in difficult and uncooperative environmental conditions. When excavating, we painstakingly trowel our walls to keep them as vertical as possible, we relocate dirt piles to prevent avalanches from falling into our units, and at the end of the day we tarp over our work to protect it until the next morning. We can take precautions like these in the field which help preserve our excavations, but occasionally Mother Nature throws us a curveball and tests our ability to think on our feet.

We had intended to excavate all of the features we found by our last day on Friday (June 16th), and after productive days on Monday and Tuesday it seemed that we would be able to reach our goal. However, over Tuesday night heavy rain fell at Aztalan, inciting flash flood warnings throughout the area. We came back Wednesday morning hoping that the tarps would have protected the pits from water damage, as they had already done for nearly 4 weeks. Even though the tarps stopped any rain from falling into the pits, removing the coverings led to disappointment: water was standing in each of the units. Test Pit (TP) 7 and 9 were flooded in their deepest sections, and TP 8 had its entire floor saturated with water. Heavy rain caused the water table to rise and flood into the units from below, something we could not have prevented. For the rest of Wednesday our progress was slow; we were able to excavate through features in the shallowest portions of TP7 and TP9, but further progress into their deeper areas was halted, along with any progress in TP8. We hoped that by Thursday, the water would have drained from the pits and we could finish excavating our last features, but the pits remained flooded. Our excavations could not continue this week.

Luckily, there is more to archaeology than just “digging”. We redirected our energy to focus on curation: cleaning, archiving, and storing the artifacts that we collected over our 3½ weeks of uninterrupted fieldwork. Curation is a vital but under-represented area of archaeology, which is often glorified in popular thought as mere exploration and treasure-hunting. Archaeologists do not conduct an excavation hoping to find “treasure”; every item from the smallest sherd of pottery to the most intricate stone tool is valuable not because of its individuality, but because of its place in a larger picture. Therefore, every artifact’s journey takes it from the field to the archaeology lab, where it is cleaned with small brushes and catalogued meticulously in trays along with other items found in the same feature. Only altogether, and in the context of soil features, can the artifacts represent a more complete physical record of a by-gone time. For this reason, curating--and thus preserving--artifacts is an integral part of the archaeological process. In fact, labwork like this takes up much of an archaeologist’s time, especially during parts of the year when fieldwork isn’t possible (or when units get flooded!).