Pueblo II: stone pueblos and the Chaco world

In the Pecos Classification Pueblo II follows Pueblo I. Houses were now built mostly of stone, sturdier and less prone to fire than the earlier jacal, and by about 1075 double-coursed walls sometimes carried a second storey. A common plan was the ‘unit pueblo’: a block of paired rooms — living rooms in front, storerooms behind — with round underground kivas and a trash mound to the south. Great kivas, some about 17 m across, served the rituals of whole communities, and towers up to about 4.5 m high stood beside the house clusters. The population grew: more than 10,000 sites were founded in the Four Corners region within 150 years, and almost every spot suitable for farming outside the floodplains was used. Farmers built reservoirs — one near Far View House at Mesa Verde is about 27 m across — and terraces of check dams to hold runoff and silt, ground maize in rows of mealing bins and made corrugated grey and black-on-white pottery, which villages with poor harvests traded for food.

By 1050 Chaco Canyon in north-western New Mexico had become the ceremonial, administrative and economic centre of the San Juan Basin. Una Vida, one of the three oldest great houses, was begun in the mid-9th century — tree-ring dates start about 860, though some accounts say about 900 — and greatly enlarged in the 10th century; after a building boom that began about 1020–1050, by the early 12th century the canyon held some fifteen great complexes of planned masonry, many of them multi-storey, such as Chetro Ketl (Pueblo Alto on the mesa top was single-storey); many apparently aligned with the movements of the Sun and Moon. Roads linked the canyon to outlying great houses across the San Juan Basin and beyond — more than 150 by the National Park Service count, while older surveys described six road systems joining about thirty outliers. The straight roads ran up to about 97 km and were up to 9 m wide, with stairways cut into the cliffs. Around 200,000 pieces of turquoise have been found in the canyon’s ruins, and many researchers think the great houses had small resident populations and filled with people only for periodic (perhaps annual) ceremonies.

The Chacoan system began to unravel around 1140, perhaps triggered by an extreme drought that began in 1130, while deforestation and arroyo cutting strained the canyon. Tree-ring dating, first applied to Chaco by A. E. Douglass, has made the canyon’s building history one of the most precisely known in the archaeological world. The Hopi and other Pueblo peoples regard Chaco as an ancestral homeland.