Pueblo I: villages of surface rooms on the Colorado Plateau

In the Pecos Classification, devised at the archaeological conference that Alfred Kidder organized at Pecos, New Mexico, in 1927, Pueblo I follows Basketmaker III. People now spent most of their time in surface buildings — rooms of jacal, a frame of posts covered with woven material and mud, and more rarely of rough masonry, sometimes on stone foundations — which stood in straight or crescent-shaped rows for living and storage, while round pit-houses gradually became kivas for ceremonies. In the Four Corners region settlements grew from five to ten pit-houses to twenty or thirty; at Alkali Ridge in south-eastern Utah about 130 surface rooms stood with 16 pit-houses and two kivas. Large villages and great kivas appeared, and farmers built reservoirs and canals to cope with scarce and irregular water.

Plain and neck-banded grey pottery was standard, with some black-on-white and red wares. People wore woven cotton clothing and blankets of turkey feathers and yucca, and hard-backed cradleboards came into use, flattening the backs of children’s skulls. In the Mesa Verde region larger public buildings appeared, which archaeologists see as the beginning of religious, economic and political institutions.

The climate was unstable: a major drought in 850–900 is documented in the Petrified Forest area, and communities moved to mesas and ridges that received more winter snow and summer rain. Around 900 the population of the Mesa Verde region declined sharply, while in Chaco Canyon great houses built from the mid-9th century heralded the flowering of Chaco in the Pueblo II period.