The setting of this study is the Lower Pecos River Region, located at the northeastern reaches of the Chihuahuan Desert within southwestern Texas and northern Mexico [ILLUSTRATION FOR FIGURE 1 OMITTED]. Near the confluence of the Pecos River with the Rio Grande, the arid landscape within this region is incised by deep canyons and arroyos. Wind and water erosion acting on the limestone substrate have produced hundreds of cavities which provided convenient shelter for the prehistoric inhabitants. Periodic occupation of the rock-shelters left behind a well-preserved archaeological record. Excavations of these dry deposits have yielded an assemblage of desiccated botanical materials spanning the Holocene, from 9750 b.p. to European contact. Likewise, the pictographic images contained within the rock-shelters of the region provide a vivid body of evidence.
The purpose of this paper is to interpret the botanical assemblage in conjunction with the art, to understand better the role that each played in the lives of the region's people. As part of the archaeological record, art as an artefact serves as a window into all components of the socio-cultural system: technological, social and ideological. By identifying plants both in the sediments and in the art, we demonstrate how examining the plant remains in conjunction with the pictographs can aid in interpreting both assemblages.
The lower Pecos region is situated at the boundary of three major vegetation zones in North America: the Tamaulipan Thorn Shrub of northeastern Mexico and southern Texas, the Edwards Plateau Oak-Juniper and the Sotol-lechuguilla/Chihuahuan Desert Shrub of Trans-Pecos Texas and north-central Mexico. Rainfall decreases east to west from 48 cm on the Devil's River to below 38 cm just west of the Pecos River. Vegetation is governed locally by position in the landscape. All of the plants listed below grow in the study area, and have been identified in the archaeological sediments of rock-shelters.
The uplands are dominated by short grasses and microphyllous shrubs, including mesquite (Prosopis glandulosa Torr.), blackbrush (Acacia rigidula Benth.), whitebrush (Aloysia grattisima (Gill. and Hook.) Troncoso), guayacan (Porlieria angustifolia (Engelm.) Gray), Texas persimmon (Diospyros texana Scheele.) and several members of the buckthorn family (Rhamnaceae). Other prominent members of the upland vegetation include the arid evergreen rosette Liliaceae, the yuccas (Yucca spp.) and sotol (Dasylirion texanum Scheele.). Typical canyon rim vegetation, especially along the very shallow soils and disintegrating bedrock outcrops, includes the evergreen rosette lechuguilla (Agave lechuguilla Torr.), leatherstem (Jatropha dioica Cerv.), coyotillo (Karwinskia humboldtiana (R.&S.) Zucc.) and wild oregano (Lippia graveolens H.B.K.). The relatively mesic conditions within the canyons and on the river terraces often support a low canopy composed of little leaf walnut (Juglans microcarpa Berl.), Texas mountain laurel (Sophora secundiflora), Gregg ash (Fraxinus greggii Gray), Mexican buckeye (Ungnadia speciosa Endl.), oaks (Quercus spp.) and Texas mulberry (Morus microphylla Buckl.). Springs, seeps and river-bank overflow ponds occur in the deeper canyons and support a variety of useful plants that include the grasses tanglehead (Heteropogon contortus (L.) R.&S.) and common reed (Phragmites communis Trin.), and sedges such as Scirpus sp. and Cyperus sp., all of which were incorporated into nests, storage containers, baskets, trays and snares.
TABLE 1. Chronology of the Lower Pecos Archaic.
period subperiod radiocarbon years b.p.
Early Archaic 9000-6000 Viejo 8900-5500
Middle Archaic 6000-3000 …