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Chaco Culture National Historical Park

by Lynne D. Escue

Exploration & Excavation in Chaco Canyon

It's believed that the first Europeans to see Chaco Canyon came in the 17th Century, when Spanish soldiers engaged in military actions against the Navajos first entered the Chaco area. Because a great many Spanish records were destroyed during the Pueblo Revolt, it's not until the 18th Century that written records document Spanish knowledge of the area. In Chaco Canyon, Archaeology & Archaeologists, the authors note that an 18th Century land grant mentions a Mesa de Chacra which was probably the eastern edge of modern Chacra Mesa near Fajada Butte in Chaco Canyon.

19th Century exploration pushed further into northeastern New Mexico; José Antonio Vizcarra describes a trip down Chaco Canyon in 1823 during which he observed that some of the canyon land was good for grazing livestock, while some could be used for dry farming.

The first substantive American knowledge of Chaco Canyon was reported in 1849 by First Lt. James H. Simpson of the U.S. Army Topographical Engineers. Although the goal of his expedition was pursuit of hostile Navajos, Simpson was so fascinated by what he found in Chaco Canyon that he took time to carefully measure and describe seven of the major ruins and several smaller ones. He obtained names for them from the Indian and Mexican guides with his party: Pueblo Pintado, Una Vida, Hungo Pavi, Chetro Ketl, Pueblo Bonito, Pueblo del Arroyo and Peñasco Blanco, names familiar to all students of Chacoan culture. Two artists in Simpson's detachment made detailed maps and drawings of the area.

After the American Civil War, photographers, scholars and travelers visited the site. Articles on Chaco Canyon began to appear in popular magazines. But it was explorer-adventurer Richard Wetherill, more famous for his excavations at Mesa Verde, who in 1895 began archaeological excavations at Chaco Canyon. An exploration company funded by wealthy New Yorkers Talbot and Frederick Hyde was set up under the direction of Professor F. W. Putnam of the American Museum of Natural History and Harvard University. Under the Hyde auspices, Wetherill and others began excavations at Pueblo Bonito the next year. At the end of the first season, a freight car containing arrows, carved wooden staffs, flutes, stone effigies cylinder jars, and a large amount of turquoise was sent East to the Hydes and the Museum of Natural History.

For his time, Wetherill's methods were scientific. Work proceeded one room at a time. The fill was shoveled off, while small tools such as knives and spoons were used to locate and remove specimens. Artifacts and architectural features were measured and mapped; artifacts were identified by number with the room they were found in; photographs were made during and after excavation. During the four-year expedition, 190 rooms were excavated in Pueblo Bonito.

The success of the Hyde expedition led other groups and individuals to begin digs in the canyon. However, at the turn of the century scholars and concerned lay people interested in preserving Native American relics and ruins in the Southwest began to protest the kind of excavations allowed at Chaco Canyon and other sites. In 1906, during the administration of President Theodore Roosevelt, Congress passed the Antiquities Act to prohibit appropriation, excavation or damage to any historic or prehistoric ruins or objects of antiquity on public lands of the United States. Another article of this act allowed the president to designate public lands containing historic landmarks, antiquities or objects of historic interest as national monuments. Chaco Canyon was one of the first 18 national monuments created by Roosevelt the following year.

By 1921, when the National Geographic Society Expedition began work at Chaco Canyon, several new archaeological techniques came into use. The first was stratigraphy, the principle that unless there is evidence of disturbance in deposited layers, material found in lower layers is older than that above it. Stratigraphy enabled archaeologists to date pottery shards. The other technique, dendrochronology, is more commonly known as tree ring dating. Under the leadership of Neil M. Judd, the expedition continued excavations at Pueblo Bonito. They not only had the advantage of field notes from the Hyde expedition, but also physiographic studies of the Chaco arroyo and changes within the site itself made between 1900 and 1901 by Professor Dodge.

Unlike the Hyde expedition which had dealt with the large amount of excavated dirt by back filling rooms previously uncovered and described, Judd planned to clear each unit, and when studies of it were complete, to leave it open and visible. The condition of Pueblo Bonito as the result of long centuries of weather, poor excavation techniques on the part of earlier expeditions, and time itself, led the National Geographic Society to fund stabilization and preservation as well as exploration. Dirt and rock excavated from Pueblo Bonito was carried away by mine cars pulled along narrow gauge track by mules.

Pottery, an important indicator of a society's evolution, was recovered in large amounts. By the close of the expedition, a stylistic progression of 21 different types of pottery could be demonstrated. It was possible to delineate the original small settlement at Pueblo Bonito and to document additions until the structure reached its final form. During the last season, Judd completed his excavations at Pueblo Bonito and examined sites on the mesa above as well as excavating the first pit house village named Shabik'eshchee Village.

Between the end of the 1920s and close of W.W. II, Chaco Canyon became a laboratory for training archaeology students from New Mexico institutions of higher education. Edgar L. Hewett, in charge of the Chaco field school, had in 1921 made some limited excavations at Chetro Ketl; now he continued excavations at the same site under his own program jointly run by the School of American Research and the University of New Mexico.

Out of this program emerged some of the best known names in Chacoan studies: R. Gordon Vivian who later joined the National Park Service, Florence M .Hawley, Anna O. Shepherd and others.

Hewett's program excavated less than half of the estimated 500 rooms in Chetro Ketl. They discovered remains of an earlier structure beneath the great house, but were unable to determine if it was the beginning of the existing building or a community that had been abandoned before construction of Chetro Ketl began. However, in places they found almost two stories of construction beneath the original Chetro Ketl structure. Among the rooms excavated in the D-shaped structure were two great kivas, one 60 feet in diameter, with niches, each containing a ritual offering or religious paraphernalia. The finds included worked and unworked turquoise, black and white stone and shell beads. Another unusual room excavated during this period was the tower kiva: a round tower two stories high, set within in a square room of the same approximate height.

Significant research was done by Florence M. Hawley, who worked with A.E. Douglass, the father of dendrochronology, in dating samples of wood from all parts of Chetro Ketl. Hawley's work made Chetro Ketl the best dated ruin in Chaco Canyon. Using the dates obtained from tests on her specimens of wood, Hawley was able to analyze the stratrigraphy of the huge pile of refuse in front of Chetro Ketl, to date the pottery found there, and compare it with pottery found in neighboring settlements.

During the 1930s, Hewett's group also excavated Casa Rinconada and Kin Nahasbas. Casa Rinconada, the largest excavated kiva in Chaco Canyon, stands by itself on the south side of the canyon, yet it is located in one of the most densely settled areas of Chaco. Like Casa Rinconada, Kin Nahasbas is a kiva independent of nearby great houses, but may have been associated with them. Another project of the lab school was the excavation of a number of smaller sites in the canyon, which led researchers to conclude that these smaller houses were not predecessors but contemporaneous with the Chaco great houses.

Unfortunately, when Hewett's lab school ended, no report of its findings was ever published, and the University of New Mexico's field school program only published reports on two of the 10 sites excavated in the Casa Rinconada area.

In 1933, the National Park Service began a stabilization program at Chaco Canyon under R. Gordon Vivian. Concentrating first on Pueblo Bonito and Chetro Ketl, water diversion, wall stabilization and replacement of previous unsuccessful stabilization materials such as cement was implemented. This was so successful that in 1937 a Civilian Conservation Corps program employing Navajo workers was set up in the canyon.

One emergency repair led to a remarkable discovery. Flooding at Chetro Ketl caused sections of the wall of a partially open first story room to weaken. Gordon Vivian determined to remove the fill from the untouched room above it, in order to relieve some of the weight on the threatened walls. When excavators removed part of a collapsed roof in this second story room they uncovered a six-inch layer of sand and silt protecting 200 carved and painted wooden artifacts. Fragments of birds as well as wands and staffs with representations of snakes and humans on them were found, some with their original painted decorations intact.

A unique discovery of a different kind came when the National Park Service began to stabilize Pueblo del Arroyo. The National Geographic Society expedition had done some excavation there, but at that date their report had not been published and weathering had reduced the area behind Pueblo del Arroyo to a formless pile of rubble. Under Gordon Vivian's restoration efforts, the circular tri-wall structure behind the pueblo re-emerged. Its uniqueness lies in the fact that it is the only such structure in the immediate Chaco area. It is significant because it shows that at the height of Chaco Canyon's greatness, there was a strong influence from the Mesa Verde area where similar structures have been found. Archaeologists debate whether the Pueblo del Arroyo tri-wall, part of a large group of rooms and kivas once attached to Pueblo del Arroyo, was ever completed and roofed. Evidence shows that the facing building stones were removed in prehistoric times.

When the National Park Service decided to stabilize the small, Pueblo III settlement of Kin Kletso, not only did they attempt to preserve the walls, the entire structure was excavated and then reinforced. Like New Alto, Kin Kletso proved to be a settlement of migrants from the north whose McElmo culture co-existed with the Chacoan culture of Pueblo Bonito and the other great houses.

A preservation effort that failed was the attempt to stabilize a huge slab of rock behind Pueblo Bonito know as Threatening Rock or Braced Up Rock (because the Anasazi had tried to shore it up by jamming logs beneath it's undercut footing, then building earth and masonry platforms and buttresses against it). The National Park Service had engineers inspect the rock to see if there was any way to stop its ages long shifting. It was recommended that they remove the sand and rocks that had accumulated behind the enormous stone slab and tie it to the canyon wall with steel cables. In the end, the only thing done was to remove the debris from behind the 30,000 ton rock.

During the night of January 21, 1941 the rock settled nine inches at the west end and 12 inches on the south. The next day park custodian Lewis McKinney took extensive measurements and photographs. When he ran out of film, he went to a trading post set up near Pueblo del Arroyo for more film. While he was inside the store there was a thunderous concussion and Threatening Rock collapsed, sending an avalanche of stone down into the back wall of Pueblo Bonito. Some 65 room were destroyed. The cost of removing tons of rock and debris from Pueblo Bonito was too high; in the end a trail was built over and around the fall of rocks, providing visitors with a scenic overlook of the area.

In 1971 new excavations began in Chaco Canyon under a group called the Chaco Center, jointly administered by the National Park Service and the University of New Mexico. Their first project was to compile an inventory of all of the archaeological remains within Chaco National Monument. Several years of surveys eventually located 2,220 sites within and immediately adjacent to National Park Service lands. In addition, over 400 examples of rock art were noted--both petroglyphs incised or pecked into the rock, and painted pictographs. Most Chaco Anasazi rock art is petroglyphs, although one of Chaco's most famous pieces of rock art, believed to record the Crab Nebula supernova of 1054, is a pictograph. Surveyors also located a network of what we believe are signal stations situated on promontories within sight of one another.

The National Park Service also supported an aerial photography program that included closed-circuit television, infrared photography and a density-slicing monitor to study the area. By changing the colors of different landscape objects transmitted by the density-slicing monitor, it was possible to chart the Chaco road system, plot the location of ancient irrigation canals and cultivated fields in Chaco Canyon and outlying areas. Studies found that, like Chaco Canyon itself, almost every outlying community had a water control system. Whether the various water control efforts in Chaco Canyon were part of one large system or individual projects is not known. The additional water may have been needed for the greater population of the Pueblo III period or the arroyo may have been cut so deeply that it was difficult to get irrigation water from Chaco Wash.

New techniques such as archaeomagnetic dating aided the excavations.

Archaeomagnetic dating permits the dating of burned pottery from the alignment of iron particles in the clay.

During excavations by the Chaco Center, four campsites from the Archaic Period were studied, followed by four Basket Maker III sites along with several Pueblo I sites. These excavations were made not only to confirm results of earlier excavations, but to better understand the development of Chacoan culture. Finally, they undertook limited excavations at Pueblo Alto because no similar structure outside of the canyon had previously been studied, and because Pueblo Alto seemed to be the terminus of many of the roads converging on the Chaco Canyon area.

In addition, a Pueblo III shrine/signal station was uncovered. This structure contains a curved masonry wall. Within the walled area a hole had been dug down to the bedrock and a stone bowl placed at the bottom of it. Over the bowl was a large stone slab holding a stone lid. The bowl inside was found to contain turquoise beads, a shell bracelet and other objects. Signal stations investigated by the team were found to be in line of sight with one another and with many of the large Pueblo III towns. Still more interesting, it was found that the only spot in the ruins from which another great house or signaling station could be seen was from its highest point, often a tower kiva. This led to speculation that one of the purposes of the tower kivas was communication.

These and other studies by the Chaco Center attempted to develop a new and better understanding of the Chaco people, their origins, society and interrelationships with neighboring peoples.

Copyright 2005 by Lynne D. Escue "Reproduction without permission prohibited."

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