Four Corners Research-Archaeology in the Mesa Verde Region

Four Corners Research ® 7823 Road 25, Cortez, CO 81321       ​
Travertine pipe.  One of 2 pipes that was left on the floor of Pitstructure 25 when the structure was deliberately burned.
T.Mitchell Pruden making notes  by "Unit 1" at Mitchell Springs circa 1914
Approximately 80 Tree-Ring were collected from the burned roof of Structure 46 at Champagne. .
The MS great kiva was built over the top of a burned over-size pit structure that was built in A.D. 787.using many beams from an earlier structure that was built in A.D. 757  Note adobe column-like veneer at the bottom of NW main roof support post..
One of several quartz crystals from the west end of the MS great kiva. Hundreds of shell and turquoise beads were found in the upper and mid fill.
Shell and turquoise was quite abundant in the Mitchell Springs Sector 11 great kiva fill.
Knife blade from floor of MS Sector 11 great kiva, from beneath floor ramp feature near the western floor vault.
Portion of the south end of Mitchell Springs Sector 11 great kiva tested in 2002.
Turquoise bead from the floor fill below the roof of the MS great kiva.
Kiva 3 circa A.D. 950.  This structure incorporated an unusual SW ventilator. Note the masonry style of this early kiva. The wall niche at center-right in photo measures almost 25 cm across.
Small MS great house (Pueblo B) showing areas tested. This structure contains a 10+ meter diameter court kiva and multi-story construction.  Thick dashed line delineates the exterior of the building. A second kiva is located in the center-left of structure and was rebuilt in the 13th century.
Excavators working on Seg 9 of Room 1 on the east end of the North Hill at Champagne Spring. This and other structures in the immediate area were abandoned around A.D. 950-1000.
Randi taking a short break from her work in Champagne Spring Structure 37. In an unusual kiva closing ritual, numerous animals were simultaneously buried inside and around a stone cairn feature which stood more than a meter tall.
Below the Champagne Spring site in Squaw Canyon, this interesting petroglyph panel contains several mountain lion figures.
Sketching the floor plan and floor features of Structure 46 at Champagne Spring. The floor had unusual floor grooves and 5 sets of paired post holes. Some of these may have been used to anchor altars that could be moved during ceremonies. Note burned roof in strata,
Structure 37 during excavations in the south end of this kiva. Over 40 animals were sacrificed and then buried. The work is very slow due to the heavy amount of documentation and cramped working conditions.
Pueblo B Court Kiva - an early to mid 1000s 40 room 2-story great house. .

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 five centuries. Construction began in the 700s and ended before 1230-1240 A.D. During this time, at least 2 curvilinear roomblocks were built immediately to the north of what developed into a small multi-story greathouse and 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 the 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, evidence to suggest the existence of an inner tower was found. The interior features of the 'tower' confirm the existence of a kiva within it.  To date, a bench coated with multiple coatings of red, white and gray layers of plaster, an adobe floor, and one large masonry lined floor vault have been documented.

    We are taking a closer look at the Mitchell Springs tri-wall in an effort to add more modern data to what is currently known about these buildings. To my knowledge, all known tri-walls except the one at Mud Springs are on publicly managed lands and it is unlikely that any excavation or productive analysis will ever take place on these until at least A.D. 2275 or beyond.  Over the last 3 months, many new discoveries have been made during the process of exposing the tops of the walls of Pueblo A and its appended tri-wall.  We are preparing a manuscript on this work and it should be ready to submit for publication early next year.

     In the ninth century the population of the Mitchell Springs Community exploded, growing to many hundreds of rooms and setting the stage for the entry of the Chaco System and the construction of  new public architecture.  Four great houses and two 10+ meter kivas were constructed at the village center.  Within the course of less than 100 years the Chacoan System had collapsed leaving diminished population levels in the Mitchell Springs community.  By 1230 or 1240 A.D. the community and large portions of the Montezuma Valley became depopulated.  People consolidated into fewer and generally larger villages and defensible locations with a source of fresh water and nearby arable fields.

     Structure 25 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 this aspect is still under investigation.  On the south side of the wingwall, the grinding of food and possibly other items was performed.  Although 22 manos and 8 pecking stones have been located so far, only two incomplete metates have been found in the portion of the structure that has been excavated so far.  Almost no bone byproducts, bone tools, debitage or flaked lithics were recovered south of the wingwall but 3 bone awls were evidently nested together in the ceiling immediately to the north of the wingwall.  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.

     Thanks to Joel Brisbin and Gay Ives, the complex stratigraphic profiles exposed by the excavation units inside the Sector 11 great kiva were documented and photographed. As part of my research questions related to the construction of special buildings on top of earlier special buildings, an early great pit structure built in 758 A.D. was tested. During excavations in the south and west ends of the great kiva the Structure 6 over-sized pit structure was discovered. 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 preplanned 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.  The central kiva may have been built with rectangular rooms above it so in effect, it may have been a round, masonry enclosed structure that was concealed from view because contemporaneously used rooms surrounded it on all sides, including above it.  During the partial excavation of Room 11 in the early 1990's, a subfloor test indicates the likely presence of earlier rooms beneath it, and beneath the central kiva.  

     Another interesting item in regard to the preplanned 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 were also used for domestic activities such as cooking and sleeping but were evidently not used for grinding operations.  Both the upper and lower floor rooms were directly connected via roof hatchways.  In the Summer of  2015 or 2016, the area on the west side of the west wall doorway in Room 18 will be tested to determine how that space was used. 

  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.......

Last version of the Mitchell Springs Tri-Wall Kiva B was appended to the west end of Pueblo A, a small 28-room 2-story greathouse.  Articulated fallen walls confirm the tower that contained this kiva stood 6-7 meters tall. It had no pilasters or visible roof offsets and the western floor vault had been largely dismantled. The outermost chamber was a little over 2 m tall while the middle chamber was over 4.  The tower that contains the central kiva stood 2 or 3 meters above the middle chamber of the tri-wall.  Note jagged stones above the bench.  This masonry is from the original tower that was 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.  
(Photo to Left) At least seven burned baskets were exposed in excavation unit 25-d on the western side of Structure 25.  They contained ears of corn or large bulk kernels.  Some of these ears were 15 cm long which is on the large side for this period of time. Atop Basket #1, was a very large re-constructable San Juan redware bowl and beneath the basket were 20-30 shaped sticks that were lashed together with an organic material that looks like leather.  This feature supported three baskets of corn and may have been an altar.
Travertine pipe. One of two pipes that were carefully placed on the floor of Pitstructure 25 (circa A.D. 850) prior to the setting of accelerant piles ablaze. The remains of at least 4 baskets full of very large ears of corn (15 cm), mats, ceramic vessels and a bag that was evidently holding this pipe were on the structure floor.
Steven Di Naso (Indiana State University) working on separating the 38 layers of mural plaster from Kiva A in Pueblo A.  Very interesting patterns of colored plasters were discovered during this laborious process.
Room 26 - We excavated the NE half of the room. Note the redeposited caliche that was brought in to fill this room.  This practice was commonly used in this part of the Mitchell Springs site and I interpret it as a deliberate attempt to 'monumentalize' these rooms .
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 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 this pueblo to left)
Excavating Pueblo I era rooms 55 and 24.  Room 24 at right was decommissioned and several offerings were put in place before the roof was dismantled and the room filled with adobe blocks and roof material.
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 Great House.  See ruined Pueblo A to the right 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.  

Oversize Pitstructure 6 - A 60+ sq meter building lies beneath the Sector 11 Great Kiva.  Note sculpted column treatment built around base of NW roof support post.  This structure was ceremonially closed at abandonment leaving the possessions of its users behind. Immense numbers of beads, hair twine, pottery vessels and other high-input items were found beneath the burned roof of finely matched Ponderosa Pine timbers.
Camping on-site.  Many new discoveries were made.  Mesa Verde is visible in background.
Click on an image above to enlarge
Sector 7 - Pueblo A Great House 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.  
Two Field School Sessions Set For 2019
at Champagne Spring Colorado

Dates:  August 16-19                    August 23-26
Place:  Champagne Spring          Champagne Spring

Details and On-Line Sign Up Coming Soon