花粉分析
Pollen analysis shows a temporary decrease in the pollen levels of trees and shrubs with a short-term increase of herbaceous pollen. The changed pollen pattern suggests an increased abundance of grass as well as a retreat of tree and shrubs. The change of vegetation distribution further indicates a colder and drier climate during this period. As for aquatic plant evidence, both aquatic and semi-aquatic botanical taxa show a sharp decrease, suggesting lower lake levels caused by drier climate. The drier climate is also reflected by increased salinity indicated by diatom analysis.