America's Architectural Heritage: Chaco Canyon, New Mexico - Part 2

Pueblo Bonito

In 1849, U.S. Army Lieutenant James Simpson was exploring northwester New Mexico when he came upon Chaco Canyon.  He noted eight large ruins, seemingly built by an ancient, unknown civilization.  The local Navajo’s and meztiso’s called the largest ruin, Pueblo Bonito, which means “pretty village.” Pottery shards on the soil surface of Chaco Canyon suggested that it was Native Americans who built the large masonry structures, but for several more decades, a wide range of fanciful stories accompanied interpretations of the ruins which assigned their origin to Romans, Vikings, Egyptians, Celts, Welsh and the 10 Lost Tribes of Israel.

In 1896 rancher Richard Weatherall and student George Pepper began excavations at Pueblo Bonito under the sponsorship of the American Museum of Natural History. The excavations were financed by the Hyde Brothers and continued until 1900. Considerable damage was done initially because the two were only looking for intact “trophy” artifacts to either sell or send back to the museum in New York.  However, the two men did photograph and map about 1/4^th of the rooms within the structure. As the two became more experienced in archaeology, their excavations methods did less damage to the archaeological evidence.

Weatherall eventually applied for a homestead patent from the U.S. Land Office in order to own 161 acres of Chaco Canyon. Samuel Holsinger of the Land Office studied the site and found archaeological features that Weatherall had missed. He recommended that Chaco Canyon become a national park. The patent was invalidated in 1904 and the land was taken over by the United States government.  In 1907 President Theodore Roosevelt signed an executive order creating the Chaco Canyon National Monument. Weatherall operated a trading post and tour guide service from the edge of the federally owned property until his death in 1910.

Professional archaeologists, sponsored by several universities and museums periodically worked on the Chaco ruins during the 20^th Century.  The University of New Mexico was one of the more important sponsors of these studies.  As the technological skills of archaeologists improved, their excavations gained more factual information and increasingly less intrusive.

In 1980, 13,000 acres were added to the original tract of the national monument.  The newly expanded reserve was then designated the Chaco Canyon National Historical Park by Congress.  The archaeological zone is managed by the National Park Service.

It is now known that when construction was started on buildings in Chaco Canyon around 850 AD, the canyon was a forested valley with running streams.  Archaeologists believe that humans completely deforested the valley to obtain fuel and construction materials.  A drought in the early 1200s AD lowered the water table and made the land unsuitable for agriculture.  It continued to be a desert into the late 20^th century.  The National Park Service is now planting vegetation in an effort to at least partially return the canyon to its original ecological state.

Architectural description

Pueblo Bonito is one of eight ‘Great Houses” in Chaco Canyon and is semi-circular in shape. The core of the structure is a massive stone masonry wall, which is aligned to the solar north-south axis. It covers roughly 2 acres and in its final form is up to five stories tall.  The walls are load-bearing ashlar masonry bonded with clay mortar.  The floors are primarily timber joists, in-filled with saplings, vegetative lathing and adobe. Estimates of its architectural contents vary from 600 to 800 rooms.  The variance is caused by the damage from the collapse of a rock cliff on a section of the ruins in 1947.

The National Park Service believes that Pueblo Bonito was constructed between 850 AD and 950 AD.  The original structure was a single story semi-circle.  Later construction added three to four more stories.  There are features in the structure which appear to be markers for following  the cycles of the sun, moon and planets.

The floor plans of Pueblo Bonito consist of terraced rooms overlooking a raised plaza and cluster of kivas.  Kivas were recessed, round rooms use for rituals. There were no entrances to the apartments from the curving exterior wall.  All were accessed from the inner plaza. The plaza itself is terraced into three levels and contains both large and small kivas.

For many decades, Pueblo Bonito and the other “Great Houses” of Chaco ‘Canyon, were believed by archaeologists to be massive apartment buildings. However, the archaeologists were puzzled because many rooms did not contain hearths, as would be expected in occupied apartments. In recent years, three dimensional analyses by architects have suggested that only 70-80 families lived in the structure, primarily on the lower level.  Families occupied 3-5 rooms as apartment units.  The other rooms were used for communal storage, or perhaps rituals.

One of the most interesting architectural features of Pueblo Bonito and some of the other “Great Houses” are the T-shaped doorways.  These are architectural features of some public buildings in the Andean Region of South America, but not a typical feature of Mesoamerican architecture.

Other archaeological discoveries

During the past two decades, archaeologists have found proof of either direct or indirect trade between outlying villages and Mesoamerica.  Perhaps half of the ceramics found in the rooms of Pueblo Bonito were made with clays from outside the canyon.  Some cylindrical jars typically used by Mesoamerican traders have also been found. Archaeologists have also found the skeletons of parrots native to Mesoamerica, plus several artifacts which probably were fabricated in central Mexico.  In 2009 residue of cacao (cocoa) powder was found in some Mesoamerican type cylindrical jars.  This discovery proves that the elite living in Pueblo Bonito consumed this prestigious beverage that was only grown in the tropical regions of Mesoamerica. As archaeological work and analysis of artifacts continues in Chaco Canyon, probably many other discoveries will be made that will broaden our understanding of this remarkable community.