概要
Chaco Canyon cuts through the San Juan Basin of northwestern New Mexico, an arid plateau at 1,900 m elevation surrounded by desert. Between approximately 850 and 1150 CE it functioned as the political, ceremonial, and redistribution center of a culture archaeologists call the Ancestral Puebloans — the ancestors of the modern Pueblo peoples of Arizona and New Mexico.
The canyon contains twelve major 'great houses' — monumental masonry structures of five or more stories, containing hundreds of rooms and multiple kivas (circular ceremonial chambers). Pueblo Bonito, the largest, was planned from the outset as a single integrated structure: a D-shaped building, 162 m across, containing approximately 650 rooms arranged in a rising crescent of masonry terraces, 2–5 stories high, with 40 circular kivas including two great kivas over 20 m in diameter. It was constructed over roughly 300 years (850–1150 CE) and was the largest building in North America until the 19th century. Chetro Ketl, Pueblo del Arroyo, and the other great houses follow similar architectural principles: massive core-and-veneer sandstone masonry, a D- or C-shaped plan, regular room arrangements, and elaborate kivas.
What makes Chaco exceptional beyond its architecture is its relationship to the wider landscape. More than 400 km of prehistoric roads radiate from the canyon to outlier great houses across a 60,000 km² territory, connecting communities as far as 150 km away. These roads — 9 m wide, dead-straight, often cut into bedrock — served as communication and redistribution channels for turquoise, ceramics, and food.
The solar and lunar alignments built into Chacoan architecture are among the most precisely documented in prehistoric North America. The main facade of Pueblo Bonito faces due south; great kiva doorways are aligned with solstice sunrises; the Sun Dagger site on Fajada Butte uses a slotted rock to cast a dagger of light on spiral petroglyphs at solstices and equinoxes. The canyon was largely abandoned by 1150 CE, possibly due to drought, social fragmentation, or the shift of power to new regional centers.