Four Corners Research-Archaeology in the Mesa Verde Region

The Mitchell Springs Ruin Group was originally noted by Lewis Henry Morgan in 1876 during his study of early Americans of the American Southwest.  He described the site and noted what has been referred to as Morgan's Tower which still stands near Mitchell Springs.  Morgan remarked that the largest mound in the group stood 10 or 12 feet tall and measured 94 feet by 47 feet.  This structure was obliterated by pot hunters with a bulldozer in 1977.  During a reconnaissance of the San Juan Watershed in the 1890's, T. Mitchell Prudden mentioned the site and provided a description and assessment of its conditione.  Several years later, he returned, and with the assistance of Clayton Wetherill and Henry Hun, conducted archaeological excavations related to his study of what has been referred to as unit pueblos or Prudden Units. 


Embedded anvil stone in Structure 25.  To the left of this stone are the right and left radius of a linx that were lying beside a ceramic 'cloud blower' pipe. On the east side of the stone a very large heirloom archaic projectile point was pointing west. It was over 4 cm wide and tall. On the north side of the anvil stone, an Abajo Red-on-Orange feather box was placed.  West of the hearth were two hide-bound shaped-stick mats or possibly altars.  On them were large baskets full of corn kernels and pottery vessels containing very large ears of corn. 

With approximately 30 sq. meters of floor space, Pitstructure 25, while small in comparison to many great pitstructures of the day, was about twice the size of a middle ninth- century household pitstructure. Its size and contents suggests it may have functioned more as a ritual structure than a household pitstructure despite the obvious intensity of corn grinding operations.
Mitchell Springs Group
1938 aerial photo showing multiple water courses draining into the Mitchell Springs Community.  This created one of the most productive farming zones in the Montezuma Valley and as such it attracted agriculturalists for centuries. Control of the upland watershed probably took place when water control features in the ninth-eleventh centuries allowed water to be diverted out of the drainages and spread onto the land between the water courses. Unit pueblo construction along these drainages boomed in the AD 900's. A very large population already made this area home during the Pueblo I period as more than 1,000 linear meters of room blocks are spread over a 2 square mile area around the central Mitchell Springs community.
Tri-Wall Kiva C lies directly beneath Tri Wall Kiva B.  Although this structure is round, it appears to date to the early AD 900s. Like Kiva B above it, Kiva C contains no pilasters or roof offsets.  It resembles a tube in shape and contains no masonry in the original construction.

Look carefully at the plastered wall in the photo and you can see an etched drawing on the walls.  A horizontal line (dato) encircles the kiva and has appended triangles. This pattern closely resembles the painted mural that was plastered onto Kiva B above it.  These two structures may be over 200 years apart in age yet both structures resemble each other in shape, features, mural design and building location.
The only ground floor entrance to Pueblo A was through this corner doorway in the south end of the pueblo.  Corner doorways are rare and are usually found inside great houses.  A massive stone slab was found on the floor just inside the room.  It would have been made by a master mason as this stone weighed over 100 lbs and was the same thickness across the slab (10 cm).  The pueblo burned and the resulting collapse brought down the entire front of the structure at one time.  The wall was still articulated and confirmed the single-story rooms stood over 3 meters tall.  The back rooms were two-story rooms.  Note the door sill of embedded wood beams.
Structure 26 Basketmaker III pit room entryway through upright slabs. Note step.
Pueblo A - Room 18, is a ground floor room that was part of the original 8-room great house.  It was probably built in the mid to late eleventh-century and last used in the early 1200s.  The entire pueblo was destroyed by a fire at around AD 1225. The second-story room above this room fell into the upper fill of Room 18 and portions of the second- story floor were found intact in the upper fill of the room.
Turtle back adobe shaped blocks were used to build the east wall of Room 47 as well as several other rooms in this room block.  This room lies beneath the outer chamber of the tri-wall and dates to the early 800s.  The wall stood a minimum of a meter and a half tall.  Room 47 contains many features that are ordinarily found in proto-kivas such as a complex sipapu, an ordinary round sipapu, and numerous oblong or oval green colored sand filled pits.
Pizza and conversation with fellow sophisticates after work.  Nothing tastes as good as pizza and beer after a day in the field...well..other than a big steak and a big ice-cold beer.
Learning about the ceramics that came from some of the excavation units at Mitchell Springs.
Examining potential tree-ring specimens from Structure 25.  Dr. Spear, a dendrochronologist from Indiana State University brought her students and worked on a joint project with Steve's regular field school from Eastern Illinois.
Map of the Mitchell Springs central complex with topography. Occupation began during the Basketmaker III period at approximately AD 650 and ended at around 1230 or 1240. Several of the large Pueblo I era pueblos evolved into multi-story greathouses. The area around Greathouse A was lived on continuously or nearly continuously for almost 600 years.
Evidence of large-scale feasting has been documented around and beneath the rare tri-wall building.  Less than 10 of these buildings have been documented. They appear to be precursors of the late Pueblo III era bi-walled buildings that are found in a number of late villages in the Mesa Verde region.  The groups of rooms in the above illustration apparently were not used as housing for households.  Even if the copious and rare ritual features that are contained inside the rooms with hearths were filled with sand or loam when they were not being used, space for sleeping would have been very limited.  These suites were built with massive amounts of storage space when compared with a sample of  40 household suites from eight other nearly contemporaneous villages where such data is available.  Several of the Mitchell Springs feast suite rooms with hearths were constructed in a unique orientation and were equipped with large numbers of ritual features that are almost always only found in pit structures.  Feasting appears to have occurred at various times here from about AD 650 (Basketmaker III era) until the tri-wall was decommissioned at about AD 1200.
Colorado Archaeological Society 80th Anniversary,Power Accumulation, Expression and Transfer at Mitchell Springs
Feasts were hosted on this space centuries before the greathouse  and appended tri-wall were built and they appear to have continued  during the use of the tri-wall.  Ritualized celebrations clearly played a role in the creation of these buildings.
Pueblo A began as a two-story 16-room building at approximately AD 1050 (black walls).  This is a small multi-story greathouse that reached it's greatest size at approximately AD 1130 (shown in overlaid photo)
Left: Cross-section sketch of the construction sequence related to the tri-wall which is attached to the west side of greathouse Pueblo A.  Excavations have focused on identifying the various construction episodes in this part of the site which began at around AD 650 and continued through about AD 1240. .
Feast preparation Room 27, located on the north side of the tri-wall structure, contains features that are typically only found in pit structures of the ninth-century. They include a floor embedded anvil stone, ventilator and deflector, sand filled pits, pot rests, a sipapu, and a floor vault.
Room 24, another House M room that was especially focused on feasting.  It was equipped a plethora of features that were used for preparing feast foods for events that were hosted in the plaza. Rooms in this house were equipped with features that are generally only found in pit structures like deflectors, sipapus, ash pits, floor vaults, paired pits, massive associated storage space and many shallow, mid-depth and deep pot rests that were used to serve warm food to large groups simultaneously.
​SE corner of great house Pueblo A looking north.  Testing of Pit Structure 28 (bottom), Kiva E (top), and Pit Structure 25 (right).  From drone, Field School Aug 8, 2017

Greathouse Pueblo B, Great/Court Kiva, note Type I masonry.  This style is similar to Type I masonry in some early Chaco Canyon greathouses.  Photo of the remodeled southern recess.
More than 600 Years of using and reusing the same physical space.  Clearly this was a power-point that was recognized by more than 20 generations of Puebloans 
Great Kiva Plan View - This structure was built into the courtyard of the largest recorded great house at Mitchell Springs.  Noted in 1870 by Lewis Henry Morgan, an early ethnographer and archaeologist, this greathouse, one of five at the site, was at least two-stories tall by Morgan's description. It was roughly mapped in 1976 just prior to its obliteration by a well-known local pothunter. 
Kiva D masonry from floor level to top of bench.  Tabular stone in this style was incorporated into the penultimate addition to the great house Pueblo A.  As is the case with all of the kivas in Sector 7, Kiva D contained no pilasters or floor mounted roof supports.  This kiva was built around AD 1000 and abandoned at about 1080 or 1100. 
​Plan view of ritually decommissioned Pit Structure 25. It burned along with the possessions of those who used it.  The floor was prepared for the final act of deliberately setting the building ablaze. Accelerants were systematically used for this purpose. Without multiple simultaneous fires and oxygen access, it was not an easy process to get a pit structure to catch ablaze. An incredible mix of perfectly usable artifacts was loaded into this pit structure just prior to setting it on fire.
Structure 26 Basketmaker III pit room abandoned in early to mid 8th century. This is one of many structures built under and around the Pueblo A great house. 
Effigy Vessel, Mitchell Springs - Pueblo A great house
Greathouse Pueblo B - Tested nearly 30 years ago excavations in 2020 will investigate specific rooms that are believed to be part of the original greathouse.  As many greathouses do, the plan changed as new groups of rooms were added.
Summer fires made for hazy conditions at Mitchell Springs Greathouse B during excavation on September 15, 2020.  The first version of this building was constructed with two-stories. The ground floor walls stand ~2m-tall and are built using Type I single-wythe masonry style that may be found in the earliest great houses to be built north of the San Juan River.
Pueblo B from drone October 12, 2020.  Earliest rooms of this great house were built sometime between AD 975 and 1025.  A great/court kiva was part of the earliest pueblo and its walls were constructed of Type I masonry.
Pueblo B - Room 3.  This room has walls that were built in what is referred to as Type I masonry.  Pueblo B is one of the earliest known greathouses in the Montezuma Valley.  Walls stand about 2 m in height and were evidently two stories tall.  Built at about AD 975-1000 this room was in use for about 200 years before it was back-filled at about AD 1200 and new rooms were added above the filled rooms.  Note outlines of window that was later filled with mortar and large stones.
The remains of 6 large Dolores Corrugated jars from the surface of one of the final rooms of the later buildings that were constructed over the top of the early Type I masonry rooms.