Palynology is widely used in paleoenvironmental reconstruction. Pollen have specific morphology and can be trace back to their parents. I used sediment samples collected from Thale Noi to assess the past environment in the study area. 16 sediment samples have been selected, extract pollen and analyze. Pollen assemblages can be divided into 3 zones followed their ecology, i.e. mangrove, back mangrove, and freshwater swamp. Mangrove, back mangrove, and freshwater swamp environment were dominated by environment Rhizophora, Acrostichum, and family Poaceae respectively. This area is possibly covered by the sea before 8,170 year BP. Then, pollen records indicate an occupy of mangrove environment at about 8,170 year BP. The mangrove was suddenly replaced by back mangrove at about 8,125 year BP. The back mangrove had prevailed and the environment returned to mangrove about 8,000 year BP. Finally, it was replaced by freshwater swamp environment.
