Culture and Ecology of Chaco Canyon and the San Juan Basin

276 Chaco Project Synthesislayout, were thought to represent storage. Thus,between A.D. 1050 and 1115 there was considerablechange within the canyon.Judge (1977s) suggested that technical improvements-e.g.,the canal system, which would delivermore water to gardens only when it rained-wouldhave had a considerable effect on production. Duringwet periods, increased surplus or energy subsidieswould require storage. Similar increases in productivityand storage may have taken place in otherlocations favorable to irrigation; e.g., Kin Bineola,where a canal system had been documented (Holsinger1901, Gwinn Vivian 1970b, 1972, 1974b; GwinnVivian and Palmer 2003).Concurrently, great houses proliferated throughoutthe southern San Juan Basin (Marshall et al. 1979;Powers et al. 1983) and the formal road system(Kincaid 1983, Lyons and Hitchcock 1977b; Nials etal. 1987; Obenauf 1980b, 1983b, 1991) was thoughtto have been constructed to link these communities toChaco Canyon (but see Roney 1992). By the lateA.D. 1080s, new construction at Salmon, and soonafter at Aztec, indicates that expansion increased in thenorthern San Juan Basin. Judge (1989:240) acceptedWindes's (1984) lower population estimate for thecanyon on a year-round basis during the late eleventhcentury; there would be more facilities to accommodatepeople who came into the canyon fromthroughout the San Juan Basin. The Great North Roadwas thought to integrate these communities into thesystem. The roads would have facilitated the transportof people and goods into the center during pilgrimagesthat were attended by increasing numbers of people.Chacoan leaders would control the scheduling andprovisioning for the events, but the basin participantswould bring goods, including subsistence items,especially from nearby communities. This would leadto increasingly complex ritual, and necessitate morecomplex leadership by those in Chaco Canyon.The period of System Reorganization from A. D.1115 to 1140 was considered a delayed response toevents that occurred in the A.D. 1080s, and especiallythe A.D. 1090s; this delayed response was thought toexplain the early A.D. 1100s evidence. In thecanyon, the construction of McElmo phase structuresor additions to existing structures indicate a return toan earlier, and lower, level of energy investment inthe construction stages (Lekson 1984a). Alsorecorded were a shift in location of trash depositionfrom formal middens to unused rooms or kivas(Windes 1982b); increased frequency of carbonpaintedwares (H. Toll and McKenna 1997); increaseduse of small mammals and turkeys (Akins 1982b);increased construction at village sites (Windes1987[I], 1993); and increased diversity in village sitestructure (Truell 1986). Chaco was thought to bemore residential and less ritual (Judge 1989:246).The brief but severe climatic fluctuations aroundA.D. 1090 to 1100 were considered responsible for apossible shift in centrality of the system from Chacoto the San Juan area. Noticeable from A.D. 1100 to1115 were the growth of numerous great houses in thenorth around A.D. 1088 and later; the recovery of asmaller proportion of Gallup Black-on-white ceramicsthat were considered a symbol of Chaco Canyonleadership; and the introduction of carbon-paintedceramics that were prominent in the north. Althoughthe new northern center at Aztec (Stein and McKenna1988) shows considerable new construction thatcontinued after A.D. 1125, involvement with thesouthern San Juan Basin communities was not clear.Judge (1989) suggested that three mechanismscould have been employed during reorganization: 1)continued use of optimal loci in the basin; 2)migration of groups from the Chaco Basin to theirplaces or origin; and 3) return to a more mobilesubsistence pattern. Although pilgrimages to ChacoCanyon may have continued, the canyon was probablyequal to either an outlying area or a second-ordercenter with primarily domestic functions. Althoughactivity in Chaco continued to increase, the focus wasdomestic, and ritual dominance had moved north.Judge (1989:247) admitted that not all archaeologistsagree with him; both Stein and Lekson suggested thatthis period represents the peak of activity for thesystem that included the entire San Juan Basin. Untilbetter chronological control of the data is worked out,it is difficult to resolve this issue.Environmental deterioration was considered thecause of the Chacoan Collapse, which took place fromA.D. 1140 to 1200. The last cutting dates in thecanyon are assigned to the early twelfth century. The50-year drought between A.D. 1130 and 1180 wasthought to have been severe enough to cause major