Explaining the relationship between prehistoric agriculture and environment at Chaco Canyon, New Mexico

Abstract

Chaco Canyon, the Pueblo settlement of New Mexico, represents one of the major cultural developments in the prehistoric Southwest. Between A.D. 900 and A.D. 1100 Chaco reached its peak of cultural florescence. This period was characterized by considerable building activities, appearance of Chaco outliers, and the construction of an extensive road system. After this period a dramatic decline in population and a cessation of building activity took place. Archaeologists call this phenomenon abandonment. In general, development and abandonment of Chaco Canyon coincided with changes in climatic conditions. Between A.D. 900 and A.D. 1100 there was a gradual increase in effective moisture and warmer temperature which proved favorable for agriculture there. With these optimal climatic conditions,development of Chaco Canyon witnessed a great increase in population. However, the Chaco Canyon region could not support a large population indefinitely because of its agricultural marginality. To solve this population-resource imbalance, Chacoan farmers of this period intensified their agricultural activities by constructing water control systems such as check dams, contour terraces, canals, and ditches. These measures worked for a while and the influence of Chaco Canyon was felt in the political, economic, and religious life of a broad geographic region. However, summer moisture began to decrease in the years between A.D. 1130 and A.D. 1180. This decrease became a full scale drought from A.D. 1157 to A.D. 1179 that seems to have severely affected agriculture and wild food resources available for the Chacoans. In addition, the Chacoan water control system designed to capture runoff probably proved to be inadequate as a buffering mechanism. Consequently, population at Chaco Canyon began to decrease and the region was abandoned after A.D. 1140. In an attempt at explaining the specific abandonment of Chaco Canyon, this thesis focuses on relationship between prehistoric agriculture and environment.