Culture and Ecology of Chaco Canyon and the San Juan Basin

Related Communities 253(Marshall et al.1979). In contrast, in the central areain and around Chaco Canyon, the soils tended to beextremely alkaline and poorly drained; thus, agriculturalpotential was minimal. Based on thisdistinction, Marshall et al. (1979:339) concluded thatthe central Chaco area represents a regional exchangecenter. It could not support itself, and it therefore. relied on some form of organization to produce aregional symbiosis that led to the emergence of astratified society in which there were peripheralleaders who controlled the production and distributionof goods.R. Powers et al. (1983) focused on the natureand intensity of the Chaco system between A.D. 900and 1175. They incorporated information from thePNM/SHPO study into their more extensivelyanalyzed sample. Evaluation of precipitation patternsindicated that the entire San Juan Basin suffered froma scarcity of water, and that dry land production ofmaize would have been extremely difficult in all but afew areas (Powers et al. 1983:284-287). Farming settlementswould require supplemental moisture (runoffthat would concentrate water in a large drainage, andwater specifically diverted to fields), or the planting ofcrops in sand dunes that had retained moisture. Sanddunes had been recorded only in a few areas of the SanJuan Basin (near the Bis sa'ani, Grey Hill Springs, andPeach Springs communities). The San Juan River andits northern tributaries were a source of perennialwater. Within the Chaco Basin today, however, thereare a few small intermittent streams along the easternChuskan slopes, plus a few seeps and wells. Flowingsprings were also found at the base of Lobo Mesa, atMexican Springs, and at Skunk Springs, but theirproductivity was not known. In Chaco Canyon, otherthan rainfall, there are the intermittent Chaco Washand a few small pools of water where there is contactwith the sandstone layers that provide a water supply(Powers et al. 1983).Sites located in areas with the highest ecologicaldiversity were found along the San Juan River and itsnorthern tributaries. Next highest diversity waslocated on the peripheries of the San Juan Basin andmajor valleys to the south and east of the Chaco Basin.Outliers located in areas with the fewest ecologicalzones were in the central Chaco Basin. AlthoughChaco Canyon had a larger number of zones nearby,most of these were small, so that the number of effec-tive or useful zones was reduced to two: the plainsgrass/shrubland, and the plateau grass/shrubland(Powers et al. 1983:293). Thus, Powers et al. (1983:301) concluded that Chaco Canyon and the centralChaco Basin were not as well suited to supporting alarge agricultural population as were the peripheries ofthe San Juan Basin .Analysis of location of outlying communitieswith regard to proximity to arable land (R. Powers etal. 1983) suggested that almost all but those communitiesin the area in and around Chaco Canyon andKin Bineola were situated on class 1 and class 2 soilsduring the period from Early Pueblo II to EarlyPueblo III. Lands with less agricultural potential weregenerally limited to the Chaco Canyon area, thecentral portions of the Chaco Basin, and the MoncuscoPlateau (northeast of the Chaco Basin). Powers et al.(1983:289) recognized that variability in precipitationcould negate the gains that good soil and hydrologyprovided in the San Juan Basin.Chaco Canyon lacked a number of resources thatwere recovered from its sites. For example, woodresources, especially ponderosa pine and Douglas-firneeded for construction and species documented inChacoan structure roofs, are found in reasonablequantities near Mount Taylor or in the ChuskaMountains 14 to 40 km away. White fir is found inthe La Plata Mountains of Colorado, a distance of 140km (R. Powers et al. 1983:292-293). Other resourcesfrom the periphery include ceramics tempered withmaterials from the Chuska Mountains (trachyte) andthe San Juan River (andesite and diorite). A numberof lithic materials indicated use of Narbona(Washington) Pass chert from the Chuska Mountains,Zuni (yellow-brown) chert from the Zuni Mountainarea, Brushy Basin chert from north of the San JuanRiver, and obsidian from the Jemez Mountains orGrants Ridge areas (Jacobson 1984). When thepresence of these materials at outlying Chacostructures was evaluated, it was apparent that thehighest percentages of these materials in specificassemblages were most often found near their sourcesor along the road that led toward Chaco Canyon, butseldom, or in very small amounts, at outlying Chacostructures not so located. Some type of exchangenetwork was thought to exist to bring these and otherresources into Chaco Canyon.