Culture and Ecology of Chaco Canyon and the San Juan Basin

Related Communities 263by the Red Mesa ceramic tradition, covered threeareas: the Red Mesa Valley; the Early Bonito Chacocore and Chuska Valley; and the Ackmen or MesaVerde area. Due to its unique typography and hydrology,those in Chaco Canyon were able to capture morerunoff to improve crop production during a period ofincreased precipitation. Although there are some difficultieswith chronometric dating, some initialChacoan structures in the canyon seem to be largerthan their counterparts in the San Juan Basin.Gwinn Vivian questioned possible interpretationsof the larger buildings, both in the Chaco core andthroughout the area encompassed by the Red Mesaceramic assemblage. Were these structures publicbuildings for the community? Do they represent anAckmen settlement pattern and architecture overlainby a Chacoan regional system? Or was the Chacosystem restricted to the core area as representative ofa gradual cultural divergence from its northern Piedraroots? If there were local enclaves with diluted patterns,the reason for the Chacoan divergence n~edexplication.By the Classic Bonito phase, when there aregood chronometric dates, the community pattern ofgreat houses in small house settlements throughout theSan Juan Basin is confirmed. There is, however,variability in the components, size, and organizationof these settlements. Because of the numerous latersites, it is difficult to discern communities withinChaco Canyon. The great house may be a scaled-Upversion of small sites with alterations until aroundA.D. 1050 when a shift to storage functions isperceived (e.g., Lekson 1984a). Gwinn Vivian (1990:305) questioned whether developments in ChacoCanyon represent a number of individual sites or anentire community. He proposed a different interpretation-thatthere were two divergent residentialpatterns reflecting two social groups, one living in thegreat houses and the other in small house sites.Although there are better moisture conditions, arising or stable water table, and decreased rainfallvariance during the Classic Bonito phase, there islonger rainfall periodicity; therefore, a need for surplusto cover some periods (e.g., the drier A.D. 1020to 1045 period, the decreased moisture of A.D. 1080to 1090, and the drought of A.D. 1090 to 1100)would have brought about a need for increased horti-cultural production through both the use of watercontrol features and movement into new areas. It is atthis time that Gwinn Vivian proposed that threemethods of farming were carried out in Chaco: theuse of akchin techniques, which rely on runoff inalluvial fans; terraced gardens; and the use of watercontrol systems with canals, headgates, dams, andditches to capture runoff from the canyon rims. Thelast requires considerable organization of labor,appears predominantly on the north side of the ChacoWash, and may reflect the differences in adaptationbetween the two culture groups living in great housesand small house sites. His model for how these twopopulations interacted is discussed in more detail inChapter 9. Here, we note that the two different agriculturaladaptations would lead to divergent paths,especially when droughts occurred (see also Judge1977; Sebastian 1988; 1992).Gwinn Vivian (1990:333-335) suggested that theearly twelfth century was a time of a dispersal ofenergy after the complexity achieved between A.D.1080 and 1090. Attempts to sustain the system in amodified form are reflected in the specializedbuildings that were constructed and the changes insettlement pattern, as earlier forms were scaled downto more manageable levels. The improVed climaticconditions of the early twelfth century may havetemporarily altered the attempts to restructure thesystem, but the mid-century drought may have cut theprocess short. He proposed that three variantsemerged: a contracted Late Bonito variant, and expandedMesa Verde and Houck variants. By A.D.1170, Chaco Canyon was considerably depopulated,but Vivian proposed that the basic cultural patternswere retained.DiscussionResearchers during 1970s and early 1980srecognized that by the late A.D. 800s, Chaco-likestructures appeared in several locations throughout theSan Juan Basin. Other than in the central core (in andaround Chaco Canyon), communities were located ongood agricultural lands near a water source. Theirdevelopment correlated with periods of increasedrainfall; changes in climatic conditions, especiallymajor drought periods, paralleled the rise and fall ofpopUlation, with final abandonment of the largerregion around.A.D. 1300.