Grain-size Characteristics of Yu Cheng Soil Profile and Its Environmental Significance in the Liyang Plain,Hunan

According to field investigation,sample and grain-size analysis,optically stimulated luminescence (OSL) and AMS 14 C dating in Yu Cheng soil profile in Liyang plain,Hunan.The characteristics of sediments in YC soil profile and the environmental change were discussed from last glacial to earlier Holocene.The results showed that sediments of YC soil profile was the eolian deposits and not fluvial sediments based on the grain size and other characteristics.The changing process of particles of coarse-becoming fine-fine-coarse-fine of YC soil profile has been found,which shows sediments of YC soil profile have well recorded the climatic environmental change during 56.00 ka BP-6.96 ka BP in Liyang plain.Five stages of climatic change could be found in Liyang plain.Five stages of climate change were following:cold and dry period(56.00 ka BP-31.80 ka BP),relative warm and wet period (31.80 ka BP-23.80 ka BP),cold and wet period (23.80 ka BP-14.80 ka BP),intensively change period(14.80ka BP-10.60 ka BP and warm and wet period(10.60 ka BP-6.96 ka BP).