Abstract
Low ridges of sediments that mark the courses of prehistoric Hohokam canal systems in the Queen Creek Delta of Arizona have been independently mapped by the U.S. Soil Conservation Service as discrete soil phases. To determine whether soil phase maps might be useful for identifying prehistoric canal systems elsewhere, previously mapped Hohokam canals in the Salt River Valley were compared with government soil phase maps. Long, narrow bands of sediments identified in the maps as discrete soil phases were found to be strongly associated with the first 10 km of individual canals, but the association diminishes as distance from the river increases. The study suggests that sediments associated with canals were transported by the water in those canals and deposited as the water velocity slowed. The high sediment build-up in the canal intake areas has implications for social structure of people using irrigation technology and may have been a problem serious enough to lead to changes in Hohokam society.