On-going archaeological survey in the Safford Valley of southeastern Arizona has revealed an extensive, well-preserved complex of prehistoric agricultural fields and water management features exhibiting sophisticated technological accomplishments (Neely & Doolittle 1996; Neely 1997; Neely & Crary 1998). A broad and varied array of these features and systems, dating between c.AD 800–1400, borders the Gila River and extends south into the foothills of the Pinaleño Mountains. These features may be generally considered in four 4 major categories.
Dry-farming fields comprise the first major category of features. Recognition of dry-farming fields is based on the linear placement of habitation sites, as well as the presence of specific artefact types and water-management features (e.g. linear borders, check-dams and terracing walls). ‘Gardens’ are often found in association with habitation sites. They may have served for the cultivation of herbs, or as seedbeds from which seedlings could be transplanted. The most spectacular of the dry-farmed field systems is a large (approximately 477,000 sq. m/0.48 sq. km) area of rock-bordered grids, interpreted by Doolittle & Neely (1998) to be fields for the cultivation of Maguey (Agave spp.).
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Figure 1: Aerial photograph of a portion of the dry-farmed rock-bordered grids field system found north of the Gila River and the present community of Pima. (Click Image to Enlarge)
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Figure 2: A ‘splash pad’ feature attached to the downslope side of a low rock-faced terrace in an irrigated field located in the foothills of the Pinaleño Mountains.
Newly recognized stone tool types have been found in dry-farmed and irrigated relic field areas. Their distribution has permitted the identification of field areas, as well as rough estimates as to field shape and size.
The second major category of features consists of irrigated fields; recognized by canals entering their boundaries. ‘Unimproved’ fields are areas cleared of rocks, but showing no other modifications. ‘Improved’ fields have at least one rock border or terrace wall forming their downslope extreme. ‘Gardens’, present as small, rock-outlined areas, comprise the third kind of irrigated field. Sluice gates, ‘splash pads’ and unique canal-end garden areas have been recorded as integral parts of these systems. Controlled amounts of water could be turned out through small sluice gates in the canal or ditch walls into smaller ditches, directly into field areas and into small rock-bordered ‘pools’ or gardens.
A third category of features is composed of systems of small earthen and rock-bordered canals taking water from natural springs and precipitation run-off to rock-faced terraced fields. Seven such systems have been discovered descending from the foothills of the Pinaleño Mountains. Because of the habitation sites paralleling their courses, the foothill canals were apparently used for both domestic water supply and agricultural irrigation. The longest and most complex of these systems is about 12.5 km in length, with a watershed collection area of at least 28.5 sq. km. In places, this canal is constructed into the sheer face of a high mesa landform some 200 ft. (65 m) above the valley floor. An associated feature, nearly 100 m in length, acted as a raised aqueduct to carry water across a drainage.
Large canals that took waters from the perennial Gila River to floodplain fields along its banks form the fourth major category of features. The shallow remnants of large canals coursing adjacent to and through very large archaeological sites, situated adjacent to the flood plain of the Gila River, and entering presently used field areas provide the evidence for these systems. Furthermore, Isadore Solomon (Ramenofsky 1984) wrote that several of the major historic canal systems functioning in the mid-1870s (and today) were rejuvenated prehistoric canals. These canals could have brought an approximate maximum of 7000 ha (17,290 acres) of land under irrigation.
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Figure 3: Detail map of a small portion of a rock-bordered irrigated field in the foothills of the Pinaleño Mountains. The areas labelled ‘P’ may have served as small gardens or as pools from which water could have been ladled to hand-water plants.
References
- DOOLITTLE, W.E. & J.A. NEELY. 1998. Ancient agricultural landscapes of the middle Gila Valley, Arizona. Final report for research grant #5834–96, National Geographic Society. Washington (DC).
- NEELY, J.A. 1997. Foothill irrigation and domestic water systems of the Safford Valley, southeastern Arizona. Paper presented to the 62nd annual meeting of the Society for American Archaeology, Nashville.
- NEELY, J.A. & J.S. CRARY. 1998. The Marijilda Canyon canal: a complex irrigation and domestic water system in the Safford Valley, southeastern Arizona. Paper presented to the 63rd annual meeting of the Society for American Archaeology. Seattle.
- NEELY, J.A. & W.E. DOOLITTLE. 1996. The Goat Hill irrigation system, southeastern Arizona. Paper presented to the 61st annual meeting of the Society for American Archaeology, New Orleans.
- RAMENOFSKY, E.L. 1984. From charcoal to banking: the I.E. Solomons of Arizona. Tucson (AZ): Westernlore Press.
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Figure 4: Undated checkdam showing double faced rubble core construction.