Culture and Ecology of Chaco Canyon and the San Juan Basin

120 Chaco Project SynthesisThe period between A.D. 850 and 864 was the longestand wettest period in the A.D. 800s; every year hadprecipitation values that were above average.Based on these interpretations of the environmentaldata, changes during the Basketmaker III andPueblo I periods should have been initiated after A.D.725 to 750 when a decline in moisture began (GwinnVivian 1990). The above-normal rainfall betweenA.D. 728 and 737 (Windes and D. Ford 1996) mayhave alleviated some of the problems brought on bythe onset of drier summers, or the drought may havestarted after this period. After A.D. 737, however,slowly declining summer moisture must have erodedthe farmers' ability to produce successful crops withoutadjustments.Possible adjustments include moving to betterwatered lands, increasing acreage under cultivation, orchanging technology, or any combination thereof(Hayes 1981). The population estimates derived byHayes indicate that there should have been sufficientavailable agricultural land to allow movement off themesa tops, where dry farming would have been theonly option. By locating along the larger tributariesto the Chaco Wash, where soils were deeper andprobably better able to obtain and retain moisture thatwas being channeled into these areas, the popUlationwas able to survive. The gradual movement frommesa tops to the valley floor correlates with thesedates. But the need to move back and forth to moredistant hunting grounds to provide animal proteinwould remain.The social organization needed to coordinate thisadaptation remains under discussion. Wills andWindes (1989) recognized that most models of socialorganization during the Basketmaker III to Pueblo Iperiod relied heavily on Roberts's (1929) report onShabik'eshchee Village. They (Wills and Windes1989:352) suggested that the band-to-clan progressionfor Chaco society that had been in vogue sinceSteward's (1937) analysis of Basketmaker III socialorganization may not be accurate. Instead, Wills andWindes (1989) proposed that the mesa top locations ofthe two large Basketmaker III sites (Shabik'eshcheeVillage and 29SJ423) were indicative of "group-leveldecision making that was situational and episodic"(Wills and Windes 1989:349).Shabik'eshchee Village was located in an areawhere access to pinon-nut harvests would have beenpossible in the fall for approximately one out of everyfour years (Wills and Windes 1989:359). Theproximity of this site to good agricultural lands in thevalley bottom during wet springs may have luredmembers into longer periods of sedentism. TheBasketmaker III occupation, therefore, is tied tosedentism, because it represents the period when theuse of stored grains would tether the population toseasonal sites.Two types of storage at Shabik'eshchee Villagemay represent two different storage tactics (Wills andWindes 1989). The antechambers attached to the pitstructures may have held crops that were used daily;the small cists or bins located outside of the pit structuresmay represent sealed facilities that would preventexposure to air and humidity (for cultigens that wouldbe needed as seeds at some future date or for longtermpreservation) or for caching of foodstuffs byhighly mobile groups. Because these cists would havebeen easily visible to the group, easily monitoredcommunal economies could have existed at this time.The popUlation would have included a resident family(or families) that remained at the site year-round, andother members who were present at intervals. Threepossible pithouse clusters in the southwestern part ofthe site excavated by Roberts (1929) may representgrowth and change in social organization amongfamilies who recycled pit structures through time.Wills and Windes (1989:359-361) proposed thatthere were two types of settlements in the canyonduring Basketmaker III: 1) typical sites that representone to three families who moved around throughoutthe seasonal cycle; and 2) large aggregations such asShabik'eshchee Village and 29SJ423, both locatednear access to arable lands, large local watersheds, andprobable pinon woodlands, which led to episodes ofpopUlation concentration. The linear distribution ofBasketmaker III sites in these two areas is not foundelsewhere on the mesa tops. Although Wills andWindes (1989:364) agreed with Lightfoot andFeinman (1982) that there was a need for group-leveldecisionmaking in large sites such as Shabik'eshcheeVillage, they did not believe that the big-man modelbest fits the data. Storage cists could not be linked topit structures; there was a lack of evidence of storage