Test excavations and architectural analysis of Big Westwater Ruin (42Sa6752) in southeastern Utah provide evidence of culture change and instability in the western Mesa Verde Anasazi area. The rockshelter was occupied by early-Pueblo II times and finally abandoned by mid-to-late-Pueblo III. Three periods of masonry construction in two separate room blocks and two episodes of destruction are identified. The first, a conflagration of construction associated with early masonry, likely occurred shortly after the ca. A.D. 900 onset of the Pueblo II period. This was followed by a period of extensive rebuilding of the two room blocks. This intermediate stage is associated with the mid-to-late-Pueblo II/early-Pueblo III occurrence of Kayenta Tusayan Polychrome and Sosi Black-on-white pottery at the site. Fourteen tree-ring dates (A.D. 1147-1207) are associated with a second phase of intermediate stage masonry construction.
The site was once again partially destroyed following the appearance of McElmo Black-on-white pottery at the site. The destruction probably occurred postdating A.D. 1207. Subsequent mid-Pueblo III late stage rebuilding and repair is associated with the installation of a series of 18 11 observation ports 11 which provide nearly full view
coverage of the alcove site location, including access and interior features. This adoption of an apparent mid-to-late-Pueblo III defensive posture is associated with a subsistence shift toward an increasing reliance on domestic turkey. Early-Pueblo II destruction and a mid-to-late-Pueblo III subsistence shift are also identified at Westwater-Five Kiva-Ruin (42Sa14) three miles to the north. The evidence at both ruins suggests considerable cultural instability shortly after the Pueblo I I introduction of masonry and corrugated pottery in this locale and again during mid-Pueblo III times. The latter may be the result of stress sometime following ca. A.D. 1150-1200 nucleation.