Variability in content and context of aboriginal rock art on the northern Colorado Plateau

The assemblage content of aboriginal rock art varies from place to place on the northern Colorado Plateau. Rock art, like other components of the physical environment, served aboriginal peoples as a source of information about the dynamics of the social and physical environment. This study examines the relationships between the morphological content of petroglyphs and pictographs and the places in which they occur along the drainage system of the Colorado River in southeastern Utah. The resource structure of this environment suggests that aboriginal peoples needed to have knowledge of the availability of potential food and non-food sources over a vast area. As the population density in this area increased, cooperation and competition between groups became more defined. With increasing population density came restrictions on the sharing of information about the resource base and territorial behavior. The assemblages of petroglyphs/pictographs at 388 locations were examined in this study. Information theory and its measures were used to assign a quantifiable index to each assemblage of rock art. In addition, the presence/absence of twelve cultural and situational features were noted for each of these locations. Hierarchical cluster analysis was used to ascertain homogeneous groups of these sites that show patterns of similarity among these twelve contextual variables. Results of the analysis show differences in rock art placed on boulders, rockshelters, and at the bases of cliffs. It is argued that rock art on boulders and at the bases of cliffs reveals the greatest information content. Displays of access restriction are considered more prevalent in rockshelters, especially those showing evidence of storage, caching, and/or habitation. It is concluded that the frequency and diversity of use of places exhibiting petroglyphs and/or pictographs is reflected in the information content of the rock art. Rock art varies with the kinds of functions these places served in the socioeconomic system of aboriginal peoples