Culture and Ecology of Chaco Canyon and the San Juan Basin

16 Chaco Project SynthesisDuring excavation, two improvements in datagatheringwere initiated. During the first few years ofthe excavation program, screening of material waslimited; by the mid-1970s, use of 'A-in screens wasstandard practice. In special circumstances, 1fB-inscreens were used to ensure the recovery of smalleritems. Prior to the 1970s, collection of samples foridentification of pollen and macrobotanical remainsfound during flotation procedures was uncommon.Under the direction of Loren B. Potter of the UNMbiology department, Anne Cully and Mollie B.Struever Toll collaborated to evaluate methods forproper sampling of various features in archaeologicalsites. They devised a grid sampling technique forfloors and features (A. Cully and Potter 1976;Struever 1977a, 1977b) that was applied initially in1975 during excavations at 29SJ627. They learnedthat undisturbed room features tended to provide moreinformation than floors or floor contact. Bothinvestigators concluded that composite pinch samplesfrom numerous spots on a room floor would yield amore representative sample than a few individualsamples taken at discrete locations. They focused ondelineating the differences between these two types ofbotanical remains and the information gained fromeach. Modem pollen rain contaminates opened areaswithin 12 hours or less (A. Cully and Potter 1976:49);therefore, pollen analysis provides more informationon the general climatic background and itsmanipulation by man. In contrast, seeds are morelikely to indicate human or rodent activity within sites(Struever 1977b: 147). Both analytical techniquesincluded a few taxa that suggested slightly wetterconditions during the A.D. 1000s than exist presently.Their combined research expanded our knowledge ofdomesticated and wild plant foods and fuels (A. Cully1985b; M. Toll 1985). The increased evidence collectedby the implementation of these two techniquesfacilitated a more detailed picture of the Puebloadaptation.Analytical TechniquesStudies of different chronometric techniques,methods for sourcing materials, and computerizationchanged dramatically in the late twentieth century.This section will discuss several new techniques thatwere implemented and evaluated by Chaco Projectstaff. Some have become standard tools; others stillneed refinements.Chronometric Studies. Although dendrochronologicalstudies, which are the mainstay inSouthwestern archaeology, were expanded andrefined, the addition of other chronometric techniquesprovided finer grained intersite and intrasitechronological control. Archaeomagnetic, thermoluminescence,and obsidian hydration dating methodswere tested. Ceramic descriptions of the Cibola WhiteWare series were refined.Dendrochronology: Sites in Chaco Canyonhave contributed to studies in dendrochronology sincethe 1920s and 1930s (Hawley 1934). The resamplingand reanalysis of wood from Chetro Ketl (Dean andWarren 1983) not only confirmed Hawley'Sconstruction phases at this great house (Lekson1983c), but also provided information on speciesselected, season of cutting, wood modification, andwood use, and an estimate of the number of treesneeded to build this and other large pueblos (Dean andWarren 1983). What became apparent were theprobable locus of sources and distance of import fornonlocal species (Betancourt et al. 1986). Continuedsampling of extant wood specimens in all abovegroundstructures has resulted in reinterpretation ofthe earliest construction phases at Pueblo Bonito, withrecognition of reuse of wood by early Pueblo peopleand the stabilization crews (Windes and C. Ford 1996;Windes and D. Ford 1996). Based on a study ofcutting and trimming practices, Windes and McKenna(2001) reviewed the labor involved in the constructionof large pueblos and its implications for socialorganization.Archaeomagnetic Dating: Initial tests of thistechnique developed by Robert DuBois of theUniversity of Oklahoma were carried out in ChacoCanyon (Nichols 1975). Windes (1987[1]) quicklymastered the procedures, designed a field andequipment manual, and taught many of his colleagueshow to take samples. By 1980, 238 samples had beencollected from the canyon. To assess the reliability ofarchaeomagnetic dating, at Pueblo Alto 123 dates werecompared with tree-ring dates. Although archaeomagneticdating provided consistent results, somedates differed by 50 to 100 years from either tree-ringdates or ceramic indicators. The archaeomagneticcurve established by DuBois for the eleventh andtwelfth centuries needed refinement (Windes 1980,1987[I]). Although Dan Wolfman revised the curve,