| Summary: | 博士 === 國立臺灣大學 === 地質科學研究所 === 92 === To detail fluctuations in climatic conditions during the late Holocene is one of the more challenging aspects of palynological study compared with conspicuous Pleistocene glacial interglacial changes. Here, pollen studies in a site of rapid sedimentation ought be useful in interpreting the climatic history of the last several millennia. The Ilan Plain, facing the Pacific in northeastern Taiwan with an area of ca. 330 km square is geologically situated near the west end of the offshore Okinawa Trough. This Plain is presently undergoing a serious subsidence and has an extremely high sedimentation rate due to the southwestward extension of the Okinawa Trough (Suppe 1984; Letouzey and Kimura 1986; Yeh et al. 1989; Liu 1995; Lai and Hsieh 2003). Twenty-meter thick sediments are found within the last 3000 years and the Holocene sediments reach 120 meters-thick based on drilling cores (Chen W. S. 2000; Central Geological Survey 2001). The existence of scattered wetlands and swamps in this deltaic plain provide good sites for studying climatic and environmental changes owing to the abundance of organic matter. In this paper, we present radiocarbon-dated pollen stratigraphy from a drilling core collected from Wuyuan, a former wetland marsh and mutually an archaeological site in Ilan Plain. The data has been interpreted in the context of climatic and environmental changes, and furthermore, we also discuss human impact, when it occurred, over the past 4200 years.
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