Culture and Ecology of Chaco Canyon and the San Juan Basin

The Classic Adaptation 181upland areas during this period alsocontributed to ready absorption of rainfall.Where such deposits overlaid fine-grainedmaterials, the percolated moisture wasagain kept within a range useful to plants,while the sands acted as an evaporationretardingmulch and prevented soils buildup.(A. Cully and Toll 1986)Studies of current conditions in the Kin Bineola andKin Klizhin sections by A. Cully and Toll (1986)indicated that both areas have a mix of saltbrushspecies tolerant of alkaline and saline conditions onthe floodplains. Although a similar mix of species ispresent on the slopes and in side drainages, these areascontain more ricegrass and sand drop seed than theuplands, which have more grasses and shrubs. TheKin Bineola lowlands are better for agricultuie tha..~those along Kin Klizhin Wash because they are lessalkaline or saline and have a higher water table.However, because soils can collect salts throughagricultural use, retrodicting today's conditions intothe past and making inferences about the potential foragriculture must proceed with caution.Several investigators provide evidence forPueblo use of three types of agriculture (dry farming,floodwater farming, and use of water control systemsto direct water to gridded fields). Akchin gardens onthe south side of the canyon and planting in dunes, onthe talus, or alongside channels would have beendependent on natural precipitation (Gwinn Vivian1992). Dry farming would have been a viable optionduring wetter periods that occurred between A. D. 900and 1150. "The persistent location of small housesnext to dry farming areas indicates that localagriculture continued to be attempted. Despite highsite density, small houses rarely encroached on dunelocations, possibly for reasons other than theirpotential for agriculture" (Truell 1986:319).Although few fields in Chaco Canyon are visibletoday, small site clusters occur at the mouths of sidedrainages and adjacent to dune deposits that mayrepresent the best dry farming areas in the canyon.Although Gillespie (1985) and Gwinn Vivian(1992) did not consider mesa tops a good location forfarming, Windes (1987[1]:120-124, Plates 5.15 and5.16) documented four areas on terraces south ofPueblo Alto where masonry walls, backed by alluvialsand, would have been well situated to enjoy morningsun, afternoon shade, and ground water seepage. Onetchamahia and a predominance of jar forms suggestagricultural activities in these areas (Windes 1987[I]:Table 5.5). Ceramic types include a few from theA.D. 900s, but the sherds date predominantly to theearly A.D. lO00s through the early A.D. 1100s.Floodwater farming was proposed for theinhabitants ofBc 362, a small site located on the southside of the Chaco Wash and on the eastern edge of anaiiuviai fan that resuited from outwash from thearroyo in Cly's Canyon (Voll1964). Voll suggestedthat sediments created a dam across the main ChacoWash during a period of aggradation. The house waslocated on a small mound composed of sandy, silty,and clayey alluvium that was topped by 0.6 m (2 ft) ofcultural material. Below this was a layer that exhibitedfine charcoal in sandy soil. At about 1.5 to 2.1 m(5 to 7 ft) was agray silty clay strata that Voll attributedto water deposition from the main channel. Theinitial occupation of five rooms and a kiva on top ofthe mound was tentatively dated around A.D. 1088based on the presence of Chaco, Escavada, Gallup,and McElmo black-on-white sherds. Expansion andremodeling around A.D. 1100 resulted in a 20-roompueblo with two kivas. The latest tree-ring dates,around A.D. 1113, suggested short use and abandonmentduring the early A.D. ll00s.Vall was unaware of the major diversion andcollection system that Gwinn Vivian (1991) documentedfor the arroyo in Cly's Canyon, where amasonry dam crosses it. Masonry at 29S11731(Vivian's B2, B4, B5, and B8) recorded by the ChacoProject survey crew was cruciform in shape andcomposed of unshaped sandstone rocks, probablyrepresenting a headgate. The masonry veneer was notMcElmo style, but was more like Classic Chacomasonry. A long depression extended from the mouthof the rincon and included sites 29S11741 and29S11750. Vivian (1991:51) identified this area asone of three examples of larger water control featuresin the canyon. During testing, Vivian (personalcommunication, 2002) recovered very few sherds;types could support either a mid- to late lO00s or amid- to late 1100s use. Vivian is fairly certain that thesystem was built by at least A.D. 1080.