A major ancient human settlement possibly dating back 4,000 years - including pit houses, the likely remnants of an irrigation canal, and human burials - has been discovered under the site of a planned shopping center in southern Arizona (USA). The settlement is likely from the Early Agricultural Period, which predates even the Hohokam culture which existed in southern and central Arizona from 500 CE to around 1450 CE.
     About 145 archaeological features found so far, including 37 pit houses, the canal, 14 other architectural features, 87 features outside the settlement, and 6 burials. The remains make the site one of a half-dozen or so from that time discovered in this region since 1993.
     Hohokam-era remains have also been found at this site, near the ground surface. The earlier remains were found about 4 metres below ground, from a period between 2000 BCE and 200 CE. The apparent canal had a U-shaped channel containing a layer of burnt charcoal, which is common for these canals. Workers also recovered an aquatic bird bone.
     While there are no certain dates, the canal could come from the period 2500 to 1500 BCE, but probably isn't older than the region's earliest canals dating to 1500 to 1000 BCE, said independent geo-archaeological consultant Gary Huckleberry, who placed this canal's construction at 1000 BCE to 1 CE.
     Discovery of this and similar sites, all along the Santa Cruz River, represent an archaeological milestone for this region, said Linda Mayro, Pima County's director of conservation and sustainability. Archaeologists have only begun to understand in the last 15 years or so that communities lived along the river up to 4,000 or more years ago, she said. Particularly important is that these communities had irrigated agriculture, usually growing maize.
     "There has indeed been a revolution in archaeological perceptions of the beginnings of agriculture in the Sonoran Desert," added Suzanne Fish, a curator of archaeology at the Arizona State Museum. "We still know a limited amount about the early years of farming, however."

Edited from Arizona Daily Star (23 March 2014)