Four Corners Research-Archaeology in the Mesa Verde Region
Four Corners Research ® 7823 Road 25, Cortez, CO 81321 ddove@FourCornersResearch.com
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. Agricultural production potential appears to have been a major contributing factor insofar as where great houses formed (link below)
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.
Production within communities with a greathouse may have transitioned from simple production methods by households or extended households to communal farming that developed enhanced water collection/distribution, mulching, terracing, check dam mini-fields, and other technologies including frost protection. These methods required far more individuals, maintenance, and managers, than a simple production economy.
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. 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 tri-walls that are known to exist. Vivian's 1959 article on tri-walls describes the only published work that I know of that involved excavation. He and his associates used relatively modern excavation and recording techniques for this work. Vivian tried to rebuild the record from earlier tri-wall excavations that had been performed at Pueblo del Arroyo in Chaco Canyon and Mound F and the Hubbard Mound at Aztec. 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. However, it is known that whatever may have been stored in the chambers was gone by the time excavators examined the deposits.
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 in the tri-wall led us to believe that the inner chamber was used as a platform for burning fires. Later tests exposed a single-wythe scabled-masonry tower that appears to have lost its Type I masonry veneer. .Later, a Chaco-style kiva was built inside of the tower. The bench of this kiva was coated with multiple coatings of red, white and gray plaster.
This part of the Mitchell Springs community was occupied continuously or-nearly-continuously for almost six centuries. Construction appears to have begun in the middle AD 600s and it ended before 1230-1240. During this time, two Pueblo I era (circa AD 825) curvilinear roomblocks were built and within 150 years, a small multi-story great house with an appended tri-wall developed over the top of the decommissioned PI houses.
Another interesting recent discovery that also involves ritualized decommissioning was documented in Pit Structure 25 which is located near the southeast corner of Pueblo A. It contained approximately 30 sq meters of floor space and may have been used by a larger segment of the community rather than by a few interrelated or cooperating families from the proximal house. Regular domestic activities were conducted inside this structure although the evidence for food processing 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 containing 3 bone awls of various sizes, were nested together in the ceiling immediately to the north of the wingwall and another set was clustered in the northeast quarter of the structure along with two large Moccasin Gray jars, and four small gray ware cups, sandals, and mats. 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 were processed from the burned roof. It is clear that tools and other implements were deliberately left in the building when it was burned and was likely related to the ceremonial closing of the building. A very similar closing occurred in Pitstructure 2, located about 60 m to the northwest. It also was deliberately burned along with its complement of attendant tools and weavings. Thirty five pottery vessels and other items were left inside the building when it was set ablaze. Another example of this closing ritual was found during test excavations in the south and west ends of the great kiva where beneath its floor, the burned remains of over-sized Pitstructure 6 was identified. It contained approximately 65 square meters of floor space and was also closed by burning immediately after abandonment. As om Pitstructure 25 and 2, 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 700s. In the mid to late 900's, the great kiva was built over it and subsequently rebuilt at least two more 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 two 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 measurable; once standing a little over 3 meters 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 noted at Salmon Ruins in Bloomfield NM. The second-story rooms above these two rooms may have been used for domestic activities such as cooking and sleeping but they were evidently not used for grinding operations.
Chaco-style Kiva A, built into the center of the greathouse, utilized masonry of a finer style than was the norm at Mitchell Springs. Like Room 18, it also burned in the fire that ended the occupation of Pueblo A and possibly the entire Mitchell Springs community. It contained an under-floor ventilator feature that 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).
DM Dove
Last version of the Mitchell Springs Tri-Wall Kiva B was appended to the west end of Pueblo A, a 28-room two-story great house. The articulated fallen walls of the tower that contained this kiva stood 6-7 meters tall. It had no pilasters or visible roof offsets. The western floor vault had been largely deconstructed in a prehistoric ritual closing event that included the loading of the floors and roofs of dismantled buildings. The outermost chamber was a little over 2 m tall while the middle chamber was approximately 4 m. The tower containing the central kiva stood approximately 3 meters above the middle chamber of the tri-wall or 6-7 m above the plaza surface. Note jagged stones above the bench. Masonry is from the original tower built in the late AD 900s or early 1000s.
The last activity inside this structure was the destruction of a large portion of the NE quadrant as well as the east and south wall of the floor vault. After that, it was sealed from further entry until the roof and walls collapsed.
Fall is a beautiful time to be in the Four Corners area. View from the center of the Mitchell Springs Community looking toward Mesa Verde.
Original version of Tri-Wall Kiva B with earlier Tri-Wall Kiva C visible beneath (see final version of Kiva B at Left). Kiva C was round, contained almost no masonry, and had no bench or pilasters. It appears to have been abandoned in the A.D. 900s. At abandonment, the room was cleaned and the roof was dismantled and collapsed onto the floor. Immediately thereafter, it was partially filled with the roof of another structure and redeposited sterile soil. The walls would have been deliberately covered in order for the preservation of the mural etchings to have survived for 1100 years.
Room 26 - We excavated the NE half of the room. Note the redeposited caliche that was brought in to preserve this room. This was a practice that was commonly used in this part of the Mitchell Springs site and I interpret it as a deliberate attempt to 'monumentalize' these rooms . Upright slabs from the walls of this room protruded 40 cm through the tri-wall plaza that was built over the decommissioned room. Over the next four centuries, the stones would have been a hindrance to open travel in the area. These walls appeared to demarcate revered space that may have been viewed as a shrine to later residents. Many of the feast prep suites were ritually decommissioned.
Click Arrow to show video. Click symbol at bottom right of video to expand to Full Screen Mode - Great House and appended Tri Wall with Pueblo I rooms converging beneath, August 2016 Field School
Survey-grade accuracy with georeferenced photo of Room 27 from drone. All of the living rooms in this room block contain features that are nearly exclusively found in pit structures.
Sleeping Ute Mountain February Sunset From Pueblo A
Pueblo A in Sector 7, Field School Aug 8, 2017, small great house and tri-wall with underlying village (rendition of pueblo to the right)
I sure appreciate the hard work and the conscientious way all of you go about doing it. We like to have fun out here and our friends who have supported these projects over the years have made that possible!
Mitchell Springs Sector 11 great kiva (west end). Note complex stratigraphy evident in excavation unit walls. These fill layers contained hundreds of beads and other completely functional tools and projectile points suggesting they were offerings.
Rendition of Pueblo A Greathouse. See ruined Pueblo A to the left of this illustration.
Subfloor ventilator in the tri-wall Kiva B at Mitchell Springs. It was replaced by an above floor ventilator in the late A.D. 1100s. Note the unburned wood that covered this masonry feature. Three of these members were collected for tree-ring samples. The Chaco-style bench recess was retained when the structure was remodeled.
Mitchell Springs Tri Wall Kiva B, original version with Chaco style features
Profiling the hearth of the Tri-Wall kiva. This unusual configuration consisted of a masonry lined cylindrical feature that was almost 40 cm deep. The more common hearth configuration contains no masonry, is basin shaped and 10-15 cm deep.
Eastern Illinois University Geology and GIS Class working at Mitchell Springs with Mesa Verde in background.
Mitchell Springs, Tri-Wall Kiva B bench mural. Many coatings of plaster survived 800 years underground. The final coating was white on the top half of the bench bottom and red at the bottom half. Large triangles and small red dots were appended to the top of the dato which consisted of a thick coat of red plaster.
This plan view sketch of Sector 7 at Mitchell Springs is overlain by an aerial drone photograph that has been georeferenced with the help of aerometric targets. We've developed a method by which archaeologists can use distortion removing algorithms and a regime of additional methods to create survey grade accuracy plan view maps. Sector 7 contains architectural remains from more than 500 years of
occupation including a small multi-story great house with a tri-wall
attached to its west side. Pueblo I and Basketmaker III structures
underlie Pueblo II and III structures.
Sculpted main roof support column treatment built around base of post. Oversize Pitstructure 6 - A 60+ sq meter building lies beneath the Sector 11 Great Kiva. Structure underwent a rarer version of decommissioning when it was deliberately burned along with the possessions of its users. Hundreds of beads, stocks of human hair twine, pottery vessels, mats, and other high-input items were underneath the burned and preserved roof of finely matched Ponderosa Pine timbers. The nearest Ponderosa stands today are 10-12 km distant and a nearer source was likely not available when ithe structure was built. This was apparently a building of high status.
Camping on-site. Many new discoveries were made. Mesa Verde is visible in background.
Click on an image above to enlarge
Sector 7 - Great House A and Tri-Wall circa AD 1200 built over converging room blocks Pueblo M and Pueblo N that were abandoned at about AD 850. Original 16-room 2-story great house is designated in black. Add-on construction came in phases starting with green rooms, then blue and finally ruby red. Note feasting facilities in Pueblo M and the continuity of occupation by two house groups for at least three centuries.
Working on Feast Suite Room 24 and Room 55 that underlies the tri-wall
New Article Published May 2021
Great House Formation: Agricultural Intensification, Balanced Duality, and Communal Enterprise at Mitchell Springs
Click Link to the Right:
