We sampled the palaeosol or buried soil of this section formed during the middle stage of last glacial at the interval of 10cm and totally we got 40 samples for spore - pollen analysis . we adopted the analytic procedure that is developed by mingjian wei ( personal communication ) to treat the spore - pollen samples 以10厘米为间距，在末次冰期中期发育的古土壤中采集孢粉样品40个，用魏明建等改进的孢粉分析方法进行样品的实验室分析，通过外加标志花粉的方法计算花粉浓度。
