Culture and Ecology of Chaco Canyon and the San Juan Basin

The Preceramic Period 93adoption of maize horticulture and the availability ofstorable surpluses was year-round occupationprobable. This, in tum, provided a foundation forlater agricultural adaptations (Elliott 1986).Gwinn Vivian (1990) examined the San JuanBasin data to evaluate a correlation between climaticchanges and cultural adaptations. He reviewed theevidence for Paleoindian, Archaic, and BasketmakerII use of the San Juan Basin to elucidate the basis forthe origins of, and clarify the processes of the systemtrajectory of, the Chaco Anasazi. Because most investigatorsused Irwin-William's (1979) description of theOshara tradition as a baseline for analysis of theirdata, they assumed that gradual cultural shiftscorrelated with changes in subsistence practices thatwere based on climatic fluctuations, particularlyprecipitation amounts and patterns (Gwinn Vivian1990:79-109).For the Paleoindian adaptation, Gwinn Vivianconsidered the availability of water one of the mostimportant factors that would have influenced thepresence of several species of animals, especiallymammoth, the major animal found in relation toClovis artifacts. There are several correlationsbetween sites and probable climatic variations.Although data are few, Clovis points have beenrecovered in the peripheries and the northern part ofthe San Juan Basin where water would have beenavailable in savannah-like areas around approximately9500 B.C. Between 9000 B.C. and 8500 B.C., therewas a drier period during which savannas andmegafauna withdrew and mammoth disappeared, onlyto be replaced with bison after 8500 to 8000 B. C. ,when increased moisture again extended grasslandsthat provided hunting territories for those using aFolsom technology. Folsom evidence is generallylimited to projectile points and appears in areas similarto those where Clovis points were found. From 8000to 6500 B.C., effective moisture decreased, andevidence for the Cody complex appears circa 6500B.C., when effective moisture that lasted until 6000B.C. is noted. Vivian (1990:81) indicated that theClovis, Folsom, and Cody complex remains areusually found on dunes and ridges above valleybottoms. His map of Paleoindian and Early Archaicsite locales (Vivian 1990: Figure 4.1) shows six areasof the San Juan Basin that were considered primarylocations (Arroyo Cuervo region, Chaco core,Gallegos Mesa, Upper Chuska Valley, Lower ChuskaValley, and Puerco Valley). Evidence for use of thedrier interior of San Juan Basin is limited.Gwinn Vivian (1990:83) contrasted the modelproposed by Irwin-Williams, who suggested that thePaleoindian hunters abandoned the San Juan Basinafter 6000 B.C. to follow large game animals eastward,with that of Judge (1982), who proposed thatenvironmental variables affected the local adaptationsand that changes in tool technology may simplyrepresent adaptations to these climatic changes.During the Eariy Archaic (5500 to 3000 B.C., or theJay and Bajada phases), Vivian acknowledged arelationship between greater aridity and changes in thelithic tool kits, specifically projectile points. The toolkits would reflect the greater adaptability to a semiaridenvironment that is somewhat similar to that seentoday. "In either case, increasing dryness probablyfostered greater concentration in localities withpermanent water" (Gwinn Vivian 1990:84).During the Late Archaic (3000 B.C. to A.D.400; San Jose, Armijo, and En Medio phases), therewere two different opinions about the climate. Irwin­Williams (1979) suggested that the climatic conditionsprovided increased effective moisture, while Judge(1982) differed. Gwinn Vivian (1990) suggested thatthe Late Archaic was not as dryas the Early Archaic,and that there was, therefore, increased plant growth.These conditions, however, did not provide sufficientgame animals for a return to hunting as a primarysubsistence strategy. Although there was an increasein human population growth, greater dependence onplants occurred. Data from the Chaco area wereconsidered similar to those reported from the ArroyoCuervo area, but there was a lack of evidence forseasonalaggregation. Simmons (1982, 1984d:l0-11),who worked just north of Chaco Canyon, thought thatChacra Mesa might have served as a winter campwhere such larger popUlations aggregated. WhenVivian compared data from a number of surveysconducted throughout the northern San Juan Basin, henoted that although Irwin-Williams's model for thisperiod was essentially substantiated, there were someminor regional differences by the Late En Mediaphase.The degree of Archaic cultural variation inthe Basin remains unclear, and the im-