A major component of our research is to explore the processes that created Chacoan outlier communities in the Montezuma Valley. A recognized pattern of development repeats throughout the region. It is clear that not every old community in the valley was suited to ascend to this role. In nearly every such case, population levels in the host community were relatively high and leadership structures and land use permissions were well established and recognized.
Some archaeologists over the last 25 years have explored the economic and social aspects and implications of moving from a small-time production system consisting of cooperating households toward a community based production system focused on creating greater quantities of food and public works projects. For about 150 years, the climate was favorable for such a development but a shift in rainfall patterns and quantities in the second quarter of the 12th Century may have added a level of stress to the system that could not be mitigated with better water collection techniques. When rain doesn't fall, there is no water to harvest or distribute.
The leadership positions within these communities provided a smooth transition from a simple method of production to one that utilized enhanced water collection/distribution, mulching, irrigation and other technologies including frost protection. Such methods required far more individuals and managers than a simple production economy. Each producer's role became more important as other steps toward a successful conversion to an enhanced production system required measured methodologies and cooperation. Breakdowns within the system probably created breakdowns in other parts of the system. Socially recognized rules and leaders would have been necessary to encourage people to work as a team.
As part of this research, investigations of the exposed portions of the tri-wall and Pueblo A has led to some new and interesting discoveries over the last few months. In 1988 and 1989, tests of the tri-wall revealed an unusual architectural configuration that was somewhat different than what can be gleaned from the 8 or 10 of these buildings that are known to exist. Vivian's (1959) seminal work on these enigmatic structures is the only published work that I know of on tri-wall's that also involved excavation. He and his associates used relatively modern excavation and recording techniques for this work. No others have been tested or excavated since. Vivian tried to rebuild the record from earlier excavations that had been performed on the Pueblo del Arroyo great house tri-wall in Chaco and the Mound F and Hubbard Mound tri-wall at Aztec with limited success. Most known tri-wall's consist of three concentric walls; the innermost being the smallest circumference and the outer, the greatest. The chambers created by the concentric walls were often further divided by cross-walls creating compartments that are generally featureless. It is likely that these chambers held perishable products however, all excavations were performed before pollen and flotation techniques were developed so at this point, no proof has been detected to confirm this. It is known however that whatever may have been stored in these chambers was gone by the time excavators had an opportunity to examine the deposits.
During the process of looking at this phenomenon further, we have focused excavations on a 40 m x 40 m section within Sector 7. This part of the Mitchell Springs Community was occupied nearly continuously for almost six centuries. Construction began in the AD 600s and ended before AD 1230-1240. During this time, at least 2 curvilinear roomblocks were built immediately to the north of what developed into a small multi-story great house that was equipped with an appended tri-wall.
Vivian concluded that the innermost concentric walls of both Mound F and the Hubbard Mound at Aztec as well as the del Arroyo tri-wall contained a building similar to a kiva. During our 1988-89 studies at Mitchell Springs, limited testing of this building led us to believe that the inner chamber appeared to have performed as a platform used for burning large fires. Recently, during tests inside this portion of the structure an inner tower was identified. A Chaco-style kiva was built inside of the tower. The bench of the kiva was coated with multiple coatings of red, white and gray layers of plaster.
Another interesting recent discovery is Pit Structure 25 which is located at the southeast corner of Pueblo A. This building contains about 30 square meters of floor space and was probably used by a larger segment of the community rather than by a few interrelated or cooperating families. Domestic activities were still conducted inside this structure although the evidence for food processing of food is somewhat confusing. On the south side of the wingwall, the grinding of maize and other items was performed. Although 22 manos and 8 pecking stones were documented, only two incomplete metates were present. Almost no de-facto trash was present. Two sets 3 bone awls of various sizes were nested together in the ceiling immediately to the north of the wingwall and another set of three awls were clustered in the northeast quarter of the structure along with two large Moccasin Gray jars, and four small gray ware cupsm ats and sandals. A hafted axe hammer, a large core, 2-hand polishing stone and a small abrading stone were also stored in the area south of the wingwall. Fragments of mats and fabric were collected from the floor just north of the ventilator opening and in the east section of space just south of the wingwall. More than 400 tree-ring samples of conifer or juniper and containing outside rings were processed from the burned roof. At this point in the excavation, it is clear that tools and other implements were deliberately left in the building when it was burned and is likely related to the ceremonial closing of the building.
During excavations in the south and west ends of the great kiva the remains of over-sized Pit Structure 6 was identified beneath the floor. It contained approximately 65 square meters of floor space and was ceremonially closed by burning immediately after abandonment. Just as we see in Sector 7 Structure 25, a large assemblage of usable tools, fabric, human hair twine, mats, baskets, ceramic vessels and ornaments were left on the floor when the building was intentionally burned in the late 8th century. In the mid to late 900's, a great kiva was built over it and was subsequently rebuilt at least two other times before being abandoned in the 1130's or 40's.
In Pueblo A , an effort to emulate a construction style which had roots in Chaco is apparent in the pre-planned footprint of the pueblo as well as some masonry style characteristics incorporated into some of the rooms. The front two rows of storage rooms on the south end of the pueblo and the 3 or 4 storage rooms on the east side of Pueblo A were single story rooms. In one event, the burning pueblo's southern wall fell southward and because it was still articulated, it was documented to be a little over 3 maters tall. The southern two rows of rooms were added to the original configuration of the pueblo, after the tri-wall structure had been appended to it. All of the remaining rooms were two-stories tall.
Another interesting item in regard to the pre-planned footprint of Pueblo A is that only two of the 22 ground floor rooms were habitation rooms. They are the only square shaped rooms in the pueblo, a trait that was also found at Salmon Ruins in Bloomfield NM. The second story rooms above these two rooms may also have been used for domestic activities such as cooking and sleeping but they were evidently not used for grinding operations. Both the upper and lower floor rooms were directly connected via roof hatchways.
Kiva A has been a fascinating bit of discovery. Some of its masonry is of a finer style than appears to be the norm at Mitchell Springs. Like Room 18, Kiva A also burned in a cataclysmic fire that ended the occupation of Pueblo A and possibly the entire Mitchell Springs Community. It has no southern recess which is not the norm for kivas built and used during this time period in the Montezuma Valley. In the space that is often reserved for a southern recess, an elaborate ventilator feature was engineered and constructed. This feature brought fresh air down into the kiva chamber from either the floor of the room above it or from atop Pueblo A. The pressure differential between the dark spaces in Kiva A in the belly of the pueblo, to the sunlit intake point 20 feet above (on the roof of Pueblo A), would have created a natural circulating cooling effect in the summer months. Regulating the airflow into the ventilator would prevent too much cold air from entering during cold nights. On one of the masonry stones that was used to create the elaborated ventilator feature (see photo below Left), an interesting petroglyph was carved.
See Mitchell Springs Tab for more information on this work.......