Culture and Ecology of Chaco Canyon and the San Juan Basin

78 Chaco Project Synthesisthe first terrace above the canyon. Owl Roost Shelter,located 30 m south of Atlatl Cave, was also brieflyexamined (Elliott 1986:80), but it contained only onepictograph on the ceiling to indicate human visitation.Gillespie (1982) attributed a lack of use of shelters toformation processes; most ofthe shelters in the Chacoarea form at the base of sandstone cliffs where groundwater seeps out along the top of the underlying, lesspermeable shale or mudstone strata. Floors areusually damp, shaly, and often steeply sloping-traitsnot well-suited to human occupation or the preservationof material culture. Atlatl Cave was different,in that the floor was 2 to 3 m above the wne ofground water seepage and much drier than mostshelters, such as neighboring Owl Roost Shelter(Figure 3.11). Just below the rockshelter were duneson which 29SJ1157 was located.asThe current vegetation of the area was describedvariable but generally sparse. Woodyshrubs are abundant around the base of thecliff, particularly in the sheltered, morerecessed areas such as Owl Roost Shelterwhere ground water seepage and less directsunlight lead to greater effective soilmoisture. New Mexico olive (Foresterianeomexicana) is dominant here with othercharacteristic wet alcove shrubs, such asSkunkbush (Rhus aromatica), also present.Atlatl Cave itself is nearly devoid of plantgrowth. The mesa top above the cliffssupports a mixed grassland and desertscrub community characterized by suchgrass taxa as Hilaria, Boute/oua andOryzopsis as well as Ephedra (Mormontea), Artemisia folifolia (Sand sage), andAtriplex confertifolia (Shadscale). Manyof these same taxa occur on the sandierparts of the bench area between the shelterand the valley bottom. Immediately abovethe cliffs is a slickrock area dominated byCowania mexicana (Cliffrose). The valleyfloor is dominated by Atriplex canescens(Four-winged Saltbush) and Sarcobatusvermiculatus (Greasewood) with Tamarix(now pervasive along the stream course).Neither juniper nor pinyon is present in theimmediate site vicinity though there are afew scattered junipers (Juniperus monosperma)within a few hundred meters. Thenearest pinyon (Pinus edulis) is more than1 km away. (Gillespie 1982:4)Excavations at Atlatl Cave and the dune siteswere carried out during 1975 and 1976. Prior to hisretirement, Mathews (1979) began a draft report butlacked sufficient information to complete it. AlthoughMathews and Neller (1979) issued a preliminarysummary of the work and Neller (1975, 1976a,1976b) began analyses of botanical remains and lithicartifacts prior to accepting employment elsewhere, itwas several years before Gillespie (1982) analyzed thefaunal remains and Elliott (1986) undertook anevaluation of the Late Archaic-Basketmaker II period.In the meantime, Judge (1982) had reviewed thePaleoindian and Basketmaker data from the San JuanBasin and noted a number of research problems thatneeded to be addressed to promote a better understandthis period. Results of these evaluations are presentedbelow.Atlatl Cave: Atlatl Cave is approximately 25m long, 4 to 5 m deep (but up to 9 m deep from thedrip line), and 2 to 5 m high. Accumulating roof fallhas elevated the floor a few meters above the surroundingterrain. A steep talus slope is located infront of the elevated area, but still under the drip line(Figure 3.12). The loose sediments containing archaeologicaland vertebrate remains are located from 1 to3 m along the back wall for the entire length of theelevated area (Gillespie 1982).Pack rat middens were present in three areas-atthe two ends of the shelter, and against the slightlyelevated roof fall. Other unconsolidated debris fromwood rat occupation is found throughout most of theshelter. It is mixed with loose sediments mainly in theupper 20 to 30 cm (Gillespie 1982). Figures 3.13 and3.14 present a plan view of the layout and excavationsin Atlatl Cave, as well as the distribution of pack ratmiddens and artifacts. During his initial analysis ofone-half of the material collected from grid 29, Neller(1975) realized that because pack rats tended to havea limited foraging range (ca. 50 to 150 m), a study ofthe materials collected by these animals would provideclues to past environmental conditions (Betancourt andVan Devender 1980, 1981). Pinon and one-seedjuniper,plus traces of Douglas-fir, hackberry, poison ivy,and wild rice, suggested slightly different conditions