We present the results of combined AMS-14C and single-grain luminescence dating of pre-Columbian irrigation canals that are part of the Racarumi Intervalley Canal System (RICS) in northern Peru. Archaeological and archival evidence suggest that the RICS was constructed during Middle Sican (A.D. 900–1100) rule and continued to operate during Chimu and Inka conquests in the A.D. 1300s and 1400s, respectively, until finally succumbing to Spanish control of the area in the early A.D. 1500s. Detrital charcoal (AMS-14C) and sand grains (OSL and IRSL) were collected from active, post-abandonment, and clean out deposits in six earthen canals located within three separate alignments of the RICS. Resulting ages confirm operation during Middle Sican, Late Sican, Chimu, and Inka control, and possibly into the early part of the Spanish period. Placed within their hydroclimatological context, RICS canal deposits document recurrent El Nino flooding ∼A.D. 1300–1600 but indicate that damage to the system was repaired and the canals continued to operate despite periodic disruptions. This study demonstrates that single-grain luminescence analysis conducted within a framework of geomorphology and formation processes has significant potential for detailed and accurate dating of ancient water-control systems.
