Munoz et al. (1) present an argument for Cahokia's demise focusing on a massive flood event ca. A.D. 1200. Although we recognize that a flood event may have occurred, we do not agree with their hypothesis that this event (i) caused the collapse of the largest Pre-Columbian city north of Mexico and (ii) occurred ca. A.D. 1200. Cahokians did not vacate the floodplain until after the mid-14th century, preceded by new communities and social relationships during the 11th to 13th centuries. We suggest the authors reconsider their data in conjunction with the prolific evidence for community persistence and revitalization initiated during the mid-12th century. First is the problematic nature of using wood and wood-derived charcoal for radiocarbon dating, i.e., the "old wood" problem. These samples can only provide the earliest possible date when organic material stopped absorbing atmospheric carbon and are not reliable for determining when that material was deposited in the floodplain lakes. At Horseshoe Lake, the proposed A.D. 1200 flood was preceded by a post-1200 date (UGAMS-14454, A.D. 1212-1269) and then followed by a pre-1200 date (UGAMS-13418, A.D. 992-1155). [All dates are from table S1 in Munoz et al. (1) and were calibrated using Calib 7.1* and the IntCal13 calibration.] At Grassy Lake, the flood postdates A.D. 1031 (DAMS-005576, A.D. 1031-1156) and predates a 15th century date (DAMS-0005575, A.D. 1428-1495). The A.D. 1200 date provided is a midpoint and not statistically meaningful. These dates suggest a much later depositional event that
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