Phytoliths recovered from column sample. According to Piperno (1984:373) "correction for C12/C13 fractionation would probably push TEM-108 [this sample] date back 400 years."
Piperno, D. R. 1984 A Comparison and Differentiation of Phytoliths from Maize and Wild Grasses: Use of Morphological Criteria. American Antiquity 49(2):361-383.