Oxygen Isotope Variability in Water Sources on the Colorado Plateau: Preliminaries to Stable Isotope Models of Prehistoric Irrigation

Summary

For aboriginal agriculturalists, subsistence strategies are tightly constrained by ecological conditions. The primary carbohydrate staple of prehistoric communities in the American Southwest (Zea mays) derives from low-altitude, subtropical conditions in Mesoamerica and is at its environmental limit on the cooler, more arid Colorado Plateau. In areas like Cedar Mesa in southeastern Utah, environmental limitations were addressed by either of two strategies. Dry farming with summer monsoonal precipitation was possible in certain periods, but was subject to variation on a yearly to centennial timescale. Irrigation using local surface water (derived mostly from snowmelt) was also used in limited areas, but required investing in construction and maintenance of irrigation features. Recent experimental work suggests that oxygen isotopes in plant cellulose can be used to distinguish irrigated from dry-farmed cultivars when compared against the isotopic variability of rain- and groundwater in a given region. The purpose of this pilot study was to measure the oxygen isotope values of water sources on Cedar Mesa, and determine whether variability is significant enough that the analysis of cellulose from archaeological maize samples could reasonably identify them as having been irrigated or dry-farmed.

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This Resource is Part of the Following Collections

• Society for American Archaeology 80th Annual Meeting, San Francisco, CA (2015)

Keywords

Spatial Coverage