Culture and Ecology of Chaco Canyon and the San Juan Basin

Basketmaker III to Pueblo I 119Families subsisted on com, beans, and squash,supplemented by protein obtained by capturing gardenpests, local rabbits, and some larger game animalsfrom the area. If Hayes's (1981) population estimatesare correct and Akins's (1985) estimate of the humanpopulation that could be fed by hunting local animalsis reasonable, then Akins's conclusion that game musthave been hunted outside of the canyon as early asBasketmaker III suggests a need for continuous movementout of the canyon by at least a small portion ofthe local population to obtain meat. That contactswith groups outside the canyon existed during BasketmakerIII and increased during Pueblo I is confirmedby the variety of sources of ceramics or their temper,lithic materials, and shell species present. Becausethere is evidence for local ceramic production, locallyavailable sources of chipped stone and ground stonetools, and much material used for site construction,the presence of imported goods may reflect 1) materialcollected during hunting excursions, 2) ties to otherrelated groups living outside the canyon who eithershared hunting areas or information regarding resourcesand their availability, or 3) trade with nonrelatedgroups.The presence of turquoise and shell offeringsduring the construction(s) ofthe great kiva at 29SJ423suggest that some traditions recorded at later sites mayhave been established during the Basketmaker IIIperiod. Akins (1985) also suggested that the presenceof the very few bear, wolf, and mountain lion partsamong the faunal material may reflect earlyceremonial items that retained meaning throughout thePuebloan occupation.DiscussionSouthwestern archaeologists recognize that lifein a semiarid environment placed restrictions on theagricultural production needed to support a localpopulation. Schelberg (1982a, 1982b) used anecological approach to outline the limitations that suchan environment placed on horticulturalists andagriculturalists in the San Juan Basin. In a stressedenvironment, inhabitants would react to even minorvariations in climate. Seasonal storage would maintainthe structure of the system and smooth out fluctuationsin the subsistence base. The amount ofenergy available insulates and controls the system,which can change only when excess energy isavailable. Perturbations can occur in either the environmentalparameters or population, leading to suchchange. In a semiarid environment, water availabilityis the major influence on energy flows that affect bothplant and animal life across space and through time.Dendroclimatological reconstructions of past environmentsoffered clues to changes in precipitation thatmight effect changes in the human adaptation.Dendroclimatological reconstructions for the SanJuan Basin were not well defined for the years prior toA.D. 900. Using paleoclimatic data from Dean et ai.(1985), and Euler et a1. (1979), Gwinn Vivian (1990:92-94) emphasized broad 50-year patterns that suggestedvariations in periods of drought on theColorado Plateau. "The most significant climatic featureof this period was the decline in total annualmoisture that began at about A.D. 725-750, reachedminimal levels about 875, and then increased toessentially the 725 levels by A.D. 1050" (Vivian1990:24). He (Vivian 1990:24) accepted a shift fromwinter-dominant to summer-dominant storm patternsaround A.D. 750 to 775 (Schoenwetter and Eddy1964). Summer monsoons were characterized ashaving greater intensity; shorter duration; and limitedsoil permeability, and thus increased runoff. Vivianconsidered two events in the period from A.D. 750 to1000 as critical-the major drought from A.D. 850 to900, and the shift in periodicity and variance ofprecipitation and storm dominance-but he recognizedthe period from A.D. 500 to 1200 as being relativelyhigh in moisture values.Judge et aI. (1981) pointed out that the droughtfrom A.D. 850 to 900 documented by Euler et aI.(1979) for the broader region was not as visible in thedata reported by Dean and Robinson (1977) for theSan Juan Basin. Additionally, after A.D. 900,summer precipitation peaks seen in the dendrochronologicaldata presented by Robinson and Rose(1979) do not always correlate with information onannual precipitation. A more detailed interpretation ofrainfall patterns in the tree-ring data of Dean andRobinson (1977) during the Pueblo I period appearedin Windes and D. Ford (1996:306-308), who indicatedthat there were several long periods (A.D. 728to 737, A.D. 850 to 864, 887 to 899, and A.D. 910to 919) when precipitation levels were above normal.