Oxygen isotopes in cellulose identify source water for archaeological maize in the American Southwest
Maize (Zea mays) was a primary food crop for aboriginal societies of the arid American Southwest. Water used for maize production in these arid zones could have come from precipitation and runoff during the summer monsoon, from perennial streams and springs, or from stored soil water fed by snowmelt. The oxygen stable isotope ratio (?18O) of summer and winter precipitation on the Colorado Plateau naturally differ by more than 10? providing a powerful tool for distinguishing winter- from summer-derived water sources used in cultivation of maize. We investigated whether variation in ?18O of potential source waters is preserved in the ?18O of cellulose (?18Ocellulose) of maize cobs by growing four aboriginal and one...