The three volumes of The Coronado Project present a wealth of information on the archaeology of the Puerco Valley of east-central Arizona. Excavations were performed at four prehistoric sites along the existing Salt River Project Coronado Coal Haul Railroad. All four sites were located on privately owned lands, and Salt River Project proceeded with this project in voluntary compliance with Section 106 of the National Historic Preservation Act as revised. Two of the sites, Cottonwood Seep and Cottonwood South, had been partially investigated prior to the original construction of the Coronado Railroad. These sites were affiliated with the Anasazi culture and had been established between the Basketmaker III and Pueblo II periods, A.D. 600-1150. An earlier Basketmaker III period, although indicated by some evidence, was not well supported by the current investigations. Sand accumulation, a particular problem in the Cottonwood Seep area along the escarpment of Hardscrabble Ridge, creates a safety hazard for the operation of the railroad with a potential for derailments. Widening of the railroad Corridor was undertaken to reduce the accumulation of sand in the road cuts and to provide areas where sand can be deposited after it has been removed from the tracks and adjacent road cuts.
