Palaeoenvironmental significance of grain-size distribution of river flood deposits: a study of the archaeological sites of the Apengjiang River Drainage, upper Yangtze region, Chongqing, China

► Grain-size of flood deposits of the archaeological sites has been discussed. ► The grain-size distribution of palaeofloods is similar to that of modern flood. ► We hypothesize the existence of seven high flood possibility layers in the QST4 unit. ► We hypothesize the existence of ten high flood possibility layers in the QST2 unit. ► The results are consistent with palaeoflood events inferred from Palynology analysis.