Chaco Culture National Historic Park

Petroglyphs at Chaco Canyon

The cultural flowering of the Chaco Anasazi began in the early AD 900s. We can see it most clearly in the architecture. They started building on a much larger scale. Using the same masonry technique as before—walls one stone thick with generous use of mud mortar—they built multistory stone villages with rooms several times larger than in the previous stage of their culture. Six of the large pueblos Pueblo Bonito, Chetro Ketl, Una Vida, Penasco Blanco, Hungo Pavi, and Kin Bineola were started at this time. This pattern of a large pueblo with oversized rooms, surrounded by conventional villages, caught on throughout the region. New communities built along these lines sprang up. Old villages built similarly large pueblos. Eventually there were more than 75 of these "towns," most of them closely tied to Chaco by an extensive system of roads.

By AD 1000 Chaco was firmly established as the political and economic center of the Chaco Plateau. There may have been as many as 5,000 persons living in some 400 settlements in and around Chaco or as few as 2,000, depending upon which assumptions are used to estimate the population. A new masonry technique the use of masonry walls with rubble cores and outer surfaces of shaped stones allowed walls to rise to more than four stories in height. Some large buildings show signs of being planned from the start, in contrast to the usual Anasazi custom of adding rooms as needed. Chaco at this time may have been the hub of an extensive political and economic system that drew in goods and commodities and directed affairs over a wide region.

How to account for this blossoming? One theory is that Chaco developed as an administrative and ritual center mainly in response to environmental fluctuations. The vagaries of weather made farming chancy. One year might be wet, another dry, one growing season long, another short. According to this theory, Chaco may have been a kind of capital that directed the agricultural life of the region, tempering good years with bad. Food could be stored here and redistributed as needed. The outlying towns can be thought of as satellites that performed for their locality the same function that Chaco did for the region.

The decline of Chaco apparently coincided with a prolonged drought in the San Juan Basin between 1130 and 1180. Lack of rainfall combined with an overtaxed environment may have led to food shortages. Even the clever irrigation methods of the Chacoans could not overcome prolonged drought. Under these pressures Chaco and the outliers may have experienced a slow social disintegration. The people began to drift away. They retreated to better watered regions, leaving behind impressive evidence of their former influence over a vast territory.

The Road System

Diagram of Ancient Roads

The true extent of the ancient Chacoan road system, as revealed by aerial photographs, impressed even veteran archeologists. There were more than 400 miles of roads connecting Chaco to some 75 communities. The longest road presently known runs 42 miles north toward the prehistoric towns now called Salmon Ruins and Aztec Ruins. On the north-south roads, settlements lay at travel intervals of approximately one day.

These roads were not simply trails worn by centuries of foot travel. They were the productions of relatively sophisticated engineering and required a great deal of energy and thought to plan, construct, and maintain. They were laid out in long, straight lines with scant regard for terrain. The roads averaged 30 feet in width. Construction was simple. On sloping ground the roadbed was leveled and a rock berm built to retain the fill.

Where the roads passed over bare rock, they were often bordered by masonry walls or a line of boulders. The roads appear to date from the 11th and 12th centuries, a time of expanding population. Several roads converged at Pueblo Alto from the north. From there well defined stairways led to the canyon bottom.

Aside from its obvious purpose of easing travel within the Chacoan world, this network could have facilitated communications and the transport of goods and materials between towns and helped bind Chacoans into a single society.

Published: 29 Apr 2002 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication


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