for storage are also found on the Peruvian south coast in the sites Quebrada de la Vaca (Andes 1960:252, 253) and at Tambo Colorado. Hundreds of stone-lined circular holes in rows have been found on a low ridge on the north side of the Pisco Valley (Shippee 1933:93; Wallace 1971:105–106). Although their role has not been determined, a hypothesis for investigation is that they were used for storage. They are between two important Inka sites (Tambo Colorado and Lima la Vieja), and very near the point where the Inka coastal road crosses the road to the highlands. They might be one of the empire's larger storage sites." In 2015, archaeologists from UCLA made a brief visit to the site, using photography from drone aircraft to create a detailed map. They speculate that the holes could have been used to measure produce given to the Inca state as tribute; the measurements might have been recorded on Incan khipus and reported to government officials. The archaeologists hope to do further studies to detect pollen or phytoliths that could tend to confirm this hypothesis. References Further reading Engel, Frederic. 2010. Arqueología Inédita de la Costa Peruana. Lima: Asamblea Nacional de Rectores. Shippee, Robert. 1933. Air Adventures in Peru. National Geographic 63(1):81–120. Silva Santisteban, Fernando. 2005. Las líneas de Nazca: otra interpretación. Lima: La Insignia. Electronic document. Urton, Gary, and Alejandro Chu. In press. The Inkawasi Khipus: An Inka State Storage Facility and Accounting Center on the South Coast of Peru. Latin American Antiquity. Wallace, Dwight T. 1971. Sitios arqueológicos del Perú (segunda entrega): valles de Chincha y de Pisco. Arqueológicas 13:4–131. External links Piotr Strzyzewski; Personal report of a 1998 trip Satellite Map Official webpage on the Peruvian Ministry of Foreign Commerce and Tourism website (in Spanish) Geology of Peru Archaeological sites in Peru