Chetro Ketl is an Ancestral Puebloan great house and archeological site located in Chaco Culture National Historical Park, New Mexico, United States. Construction on Chetro Ketl began and was largely complete by 1075, with significant remodeling occurring in the early and mid-1110s. Following the onset of a severe drought, most Chacoans emigrated from the canyon by 1140; by 1250 Chetro Ketl's last inhabitants had vacated the structure.
The great house was rediscovered in 1823 by the Mexican governor of New Mexico, José Antonio Vizcarra, and in 1849 Lieutenant James Simpson of the United States Army Corps of Engineers documented the major ruins in Chaco Canyon. Edgar L. Hewett, the director of the first archeological field school in the canyon, conducted excavations of Chetro Ketl during 1920 and 1921, and again between 1929 and 1935.
Chaco scholars estimate that it required more than 500,000 man-hours, 26,000 trees, and 50 million sandstone blocks to erect Chetro Ketl. The great house is a D-shaped structure; its east wall is 280 feet (85 m) long, and the north wall is more than 450 feet (140 m); the perimeter is , and the diameter of the great kiva is . Chetro Ketl contained approximately 400 rooms and was the largest great house by area in Chaco Canyon, covering nearly . Chetro Ketl lies from Pueblo Bonito, in an area that archeologists call downtown Chaco; they theorize that the area may be an ancestral sacred zone. Chetro Ketl contains architectural elements, such as a colonnade and tower kiva, that appear to reflect a Mesoamerican influence.
Chetro Ketl's purpose is widely debated but many archeologists believe the building was a place of large-scale ceremony that held an important position within the larger Chacoan system. It may have been occupied primarily by groups of priests and, during times of ritual, pilgrims from outlying communities. Archeologist Stephen H. Lekson believes Chetro Ketl was a palace inhabited by Chacoan royalty, and the scale of its construction was motivated by what architects call "massing": building imposing structures with the intent to impress onlookers. The building has deteriorated significantly since its rediscovery in the early 19th century, and its usefulness as a source of information about Chacoan culture is slowly diminishing.
Background
During the 10th to 8th millennia BCE, the San Juan Basin was occupied by Paleo-Indians known as the Clovis culture () and the Folsom tradition (8,500 to 7,500). Projectile points found in the vicinity of Chaco Canyon suggest that hunters may have been active in the region as early as 10,000. By 6,000 the Picosa culture had developed from within the Paleolithic population, as environmental changes caused the eastward movement of animals and people to the Southern Plains, bringing Southwestern and northern Mexican cultures into the San Juan Basin. Cynthia Irwin-Williams proposed that the first human presence in Chaco Canyon dates to a hunter-gatherer society that she named the Oshara tradition, which developed within the local Archaic () Picosa population.: Oshara; : Oshara as subgroup of Picosa. The Oshara occupied portions of northwestern New Mexico, northeastern Arizona, southeastern Utah, and central and southwestern Colorado. They harvested jackrabbits in the basin as early as 5500. Irwin-Williams divided the Oshara Tradition into six phases, and during the Armijo phase (1800 to 800) the Arroyo Cuervo area east of Chaco Canyon saw the introduction of maize and the use of rock shelters. She hypothesized that this period saw the beginning of seasonal gatherings of people from around the San Juan Basin, who eventually began to aggregate into larger social units.
By 200 BCE, the Basketmaker culture had begun to develop from the Oshara Tradition. At least two groups of transitional Basketmaker II people inhabited the San Juan Basin during this period, as increased rainfall allowed for sustained agriculture and permanent settlements by 1 CE, when the water table rose and intermittent streams became more reliable. During the first four centuries CE, the Basketmaker II people established pit-houses at elevated locations near sources of water and arable land. Brian M. Fagan notes that the development of pottery in the area during the 4th century permitted the boiling of maize and beans for the first time, and "must have brought a revolution in cooking". This period also marked the introduction of the bow and arrow to the region.
Parts of the San Juan Basin saw plentiful rainfall during the 5th to 8th centuries, leading to significant expansion of pit-house communities. Population increases during the 6th century led to the settlement of the area's lowlands, including Chaco Canyon, as the Basketmaker II people changed from a primarily hunter-gatherer society to one based on farming. This culture is known as Basketmaker III, and by 500 at least two such settlements had been established in Chaco Canyon. An important phase of Basketmaker III people is known as the La Plata. One of the earliest La Plata phase sites, Shabik'eshchee Village, was continuously occupied until the early 8th century, when the canyon was home to a few hundred people. Several clusters of Basketmaker III sites have been identified in the vicinity of Chetro Ketl.
As the Basketmaker III people improved their farming techniques during the 8th century, the well-watered areas of the San Juan Basin became densely populated. Greater crop yields necessitated the construction of above-ground storage facilities, which were the first large-scale construction projects in the region. Fagan identifies this as the beginning of the first pueblos, "ushering in a period of profound social tension, population movements, and political change." In his opinion, "by 800, there was no going back. The people of Chaco and elsewhere were locked completely into economies based on maize and bean cultivation." Archeologists refer to the period starting as the Pueblo I Period. By the early 10th century the large pit-house settlements had been supplanted by modular construction that later served as the foundation for the Ancestral Puebloan great houses. This marks the beginning of the Bonito Phase. During the 10th century, Chaco's population was swelled by a steady influx of immigrants from the San Juan River, approximately north. Fagan notes, "Within a few centuries, as rainfall became more irregular and life less predictable, the Chacoans embarked on a cultural trajectory that melded ancient traditions with new ideas that were to crystalize into a brilliant and short-lived Southwestern society."
Location and alignment
Chaco Canyon lies at the geographic center of the San Juan Basin. It is located in northwestern New Mexico north of Interstate 40 and from Gallup, the nearest city. The continental divide is east. Chaco Canyon was created by the Chaco River, which cut several hundred feet into Chacra Mesa. The elevation of the sandstone canyon and the surrounding high-desert terrain is approximately . Though most of the Chacoan sites are located at the bottom of the canyon, the group also includes some ruins not in the canyon proper, extending from Kin Ya'a in the south to Pueblo Alto in the north, and from Pueblo Pintado to the northeast and Peñasco Blanco in the southwest. In terms of water drainage and cultural affinity, the area is part of the San Juan Basin, which includes Mesa Verde in Colorado and Kayenta, Arizona.
Chetro Ketl lies east of Pueblo Bonito, in an area that archeologists call downtown Chaco.: downtown Chaco; : east of Pueblo Bonito. Scholars theorize that the area may be an ancestral sacred zone demarcated by a low masonry wall that encloses Chetro Ketl, Pueblo Bonito, and Pueblo del Arroyo. Chetro Ketl's position is symmetrical to Pueblo Bonito; the buildings are equidistant from a north–south axis that runs across the canyon. Anna Sofaer proposed that many of the great houses in Chaco Canyon were constructed to emphasize astronomical alignments; during the minor lunar standstill, the full moon rises along Chetro Ketl's back wall.
Chetro Ketl is located opposite a large opening in the canyon known as South Gap, which helped maximize the building's exposure to the sun while increasing visibility and access to the south. Its rear wall runs parallel to the canyon, and at less than from the cliffs its proximity allowed inhabitants to benefit from passive solar energy emanating from the rocks.: less than 100 feet from the cliffs; : rear wall is parallel to the canyon. Chetro Ketl is not perfectly aligned to the cardinal directions, but its nominal southerly orientation further enhanced solar exposure to its tiered rooms.: not aligned to the cardinal directions; : southerly orientation.
Construction Like other great houses in Chaco Canyon, Chetro Ketl was built over an extended period, during which the Ancestral Puebloans quarried large amounts of sandstone from the surrounding canyon.: built over an extended period; : sandstone. W. James Judge describes the period from 1030 to 1130 as "Chaco's golden century, a period virtually unmatched elsewhere in the pre-Columbian Southwest". By 1085, the Chacoans had constructed great houses at Chetro Ketl, Pueblo Alto, and Pueblo del Arroyo, during what Fagan describes as "a time of extraordinary growth and outreach".
Timber
In 1983, dendrochronology of wood samples from Chetro Ketl provided information on species selected, season of cutting, wood modification and use, as well as an estimate of the number of trees required to build the great house. Trees were harvested for construction at Chetro Ketl annually, which contrasts with the sporadic patterns found at other sites in the canyon. Whereas a late summer and early fall harvesting time has been documented at other Chacoan sites, the tree felling for Chetro Ketl was undertaken primarily during the spring and early summer. This may indicate that enough in-house labor was available during the farming season, or that specialized groups of Chacoans were dedicated to tree felling irrespective of the agriculture cycle, when most others were busy with field preparation and planting. One particularly well sampled room suggests that wood was cut during the relatively short span of a couple of weeks per season.
The most commonly harvested tree species was ponderosa pine; the Chacoans felled approximately 16,000 of them for use at Chetro Ketl, and the species is now absent from the canyon. Archeologists Florence M. Hawley and Neil Judd proposed that a plentiful forest may have existed in and around the canyon during the 10th and 11th centuries, but was eventually destroyed by over-harvesting. Dean and Warren believe this is unlikely, but the presence of trees in the canyon during the 20th century "suggests that some pines may have been locally available for use in the large towns". In their opinion, "the harvesting of trees for Chacoan construction must have decimated ponderosa pine stands and forests for many miles in every direction from Chaco Canyon." Archeologists believe the trees were processed where they were cut, then carried, not dragged, back to Chaco Canyon.
A 2001 analysis of strontium isotopes indicates that after 974 the Chacoans harvested architectural timbers primarily from two locations: the Chuska Mountains and Mount Taylor, in the San Mateo Mountains, both located approximately distant. Despite their equal proximity, they did not harvest from the Nacimiento Mountains. The selection of timbers from the Chuska and San Mateo ranges, and the avoidance of those from the Nacimiento Mountains, suggests that "regional socioeconomic ties" factored more heavily into timber procurement than "resource depletion with distance and time".