The Great Houses or Pueblos constructed in Chaco Canyon were the high-water mark of architectural development reached during what is dubbed by western archeologists as the Classic Pueblo Period (approximatly 1000 to 1300 A.D.) by a people who in the present day are referred to as Anasazi.
Most of these pueblos were multi-storied, south-facing and terraced to maximize solar gain. Their plazas were usually walled in on the south by a one-story building unit. All the Great Houses of Chaco Canyon were on the north side of Chaco Wash and most used the north wall of the canyon both as a windbreak and a solar heat collector. Preparation activities for the construction of these structures included quarrying and dressing tons of sandstone and, with human labor, hauling it several miles to a building site along with large quantities of sand, clay, and precious water needed for the adobe mix. Each Pueblo used hundreds or thousands of wooden beams, many of which were a foot in diameter and several yards long, for roof supports, lintels, scaffolding, and other structural needs. Wooden posts used to support the roofs of Great Kivas approached a yard in diameter, and tens of thousands of narrow poles were required for ceilings and roofs. As many as 215,000 trees went into the construction of the Great Houses and Great Kivas at Chaco. All were cut by controlled fires or with stone axes and then hand-carried to the building sites from forests that were as far away as fifty miles.
The Road System
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 Canyon 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 road 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.
During Classic times, Chaco was the center of a far-flung network. Goods were exchanged internally within the Chacoan system and externally with groups as far south as Mexico. Chaco's distinctive Cibloa black-on-white pottery may have originated in out-lying towns to the south and west. One estimate is that only about 20 percent of the pottery used here was made here. This may have been because there was better clay in other villages and more wood available for firing the vessels.
What Chaco lacked in pottery it more than made up for in turquoise ornaments. Raw turquoise was imported from distant mines and transformed with exquisite craftsmanship into necklaces, bracelets, and pendants. Great quantities of such jewelery have been found here, more than at any other south-western site. This small frog carved in jet, found in Pueblo Bonito, has eyes and a collar of turquoise.
Other evidence of the trading system are the many seashells (often strung into necklaces), copper bells, and remains of macaws or parrots found here. The two latter items suggest contact with Mexico, perhaps with the ancient Toltecs.
The people of Chaco were skilled masons. Working without metal tools or any written mathematics, they put up vast communal buildings that still compel admiration. Their methods evolved over centuries. The earliest dwellings were constructed with simple walls one stone thick, with generous courses of mud mortar. The oldest walls in Pueblo Bonito used this type of masonry 1. When the Chacoans began to build higher and more extensively, they employed walls with thick inner cores of rubble and fairly thin veneers of facing stone. These walls tapered as they rose, evidence of the planning that went into the large-scale construction of Classic times (1020-1120). An early example of this type of wall 2 is characterized by large blocks of irregular sandstone chinked with smaller stones set into the mortar. About half the ground floor of Pueblo Bonito was built in the style of masonry types 3 and 4 (late 11th century). Oddly enough, both styles were employed at roughly the same time. Though the patterns are pleasing, there's evidence that plaster covered the stone-work. The last distinctive masonry style, called McElmo 5, appears in Kin Kletso, a late 11th century dwelling. Its walls were built with a thin inner core of rubble and thick outer veneers of shaped sandstone, somewhat similar to the masonry styles used at Mesa Verde. To some eyes, it's less workmanlike than the earlier types, but the Chacoans may have thought differently.
WUPATKI MESA VERDE AZTEC CHACO CANYON