Culture and Ecology of Chaco Canyon and the San Juan Basin

180 Chaco Project Synthesispredominantly eight-rowed cobs, while the Gallup andLate Mix ceramic periods had lO-rowed cobs. Largercobs and more I2-rowed than 8-rowed cobs appear inone Basketmaker III site (29SJ628) and one Red Mesasite (29SJ1360).During the Red Mesa ceramic period, there was. wide use of all categories of wild plants. Economicannuals (i.e., goosefoot, winged pigweed, pigweed,purslane, cocklebur stickweed tobacco, and possiblygroundcherry, stickleaf, and beeweed that appeared inBasketmaker III and Pueblo I sites) were found ingreater numbers and less patchy patterns (M. Toll1985, I993b). Com ubiquity is at its lowest levelduring the Early Bonito phase. Data from PuebloAlto indicate a steady and perceptible increase inubiquity of com through time; at the same time thereis a diminution in the presence of some perennials. Bythe Late Mix ceramic period (Late Bonito phase, earlyA.D. lIOOs), a robust type of com is found in threegreat houses: Pueblo Bonito, Pueblo del Arroyo, andTalus Unit No.1. In contrast, com remains from UnaVida, Kin Nahasbas, and Pueblo Alto, plus cobs fromthe Bis sa'ani great house, are much smaller (M. Toll1985, 1987).Variability is also present in the San Juan Basinat Salmon ruin, where the Chacoan occupation wascharacterized by cobs with 12 rows versus the 10-rowed cobs among later remains. When ChacoCanyon data are compared with Salmon ruinspecimens, however, the cobs and cupules from theChacoan occupation at Salmon are even larger as therow number decreases. Toll attributed these morphologicaldifferences to variability in growing conditionsand redistribution rather than racial variation. Thelarger cob sizes may reflect better growing conditionsin an area that has a permanent water source.There is no information on when and how agriculturalpests or other perturbations affected cropproduction (Gillespie 1985). The severity of anyproblem would depend on how much land wasavailable for multiple planting and overplanting,population density, improvements in technology,ability to increase reliance on hunting and gathering,or the ability to rely on inhabitants from other areas ofthe San Juan Basin through food exchange.Land Available and Used for AgricultureNot all lands in Chaco were equally good foragriculture.The tilt of the rock strata ... has resulted inthe exposure of eroding shale at the foot ofthe southern cliffs, and deep alluviation onthe north side where the floodplain in someplaces laps the foot of the rock.... Soildeposited around the walls of Bonito andChetro Ketl and stratigraphy exposed in thechannel demonstrated that from 2 to 5 feetof soil were added since those walls wereerected.... When the wash was still a shallowchannel, occupants on the north side weremore subject to the danger of occasionalhigh water than the people across thevalley, but the southern exposure made forshorter winters. (Hayes 1981:61)Soils were not uniform on the canyon floor (D. Love1977b, 1980). Those along side canyons and nearside-canyon mouths were locally derived; they weresandier and contained well-crystallized kaolinite. Incontrast, soils from the Chaco drainage had poorlycrystallized illites and montmorillonites (Ross 1978).Soil samples taken from the "post-Bonito channel" andanalyzed for Judd (1964:230-231) were impervious towater and contained an excess of sodium and a scarcityof soluble calcium. A. Cully and Toll (1986) assessedconditions as follows:Geomorphic conditions during the Anasaziperiod provided an additional environmentalaspect temporarily favorable tofloodwater and dry farming. D. Love(1977a) suggests that shallow, anastomosedchannels characterized most natural drainagebasins in this period. Flow in thesechannels (concentrated from a wider area)was spread over 30-60 centimeters ofwindblown sands and silts trapped byvegetation, and kept within root depths ofcrops by underlying finer-grained alluvialdeposits. Large-grained eolian deposits in