Environmental change and Neolithic settlement movement in the lower Yangtze wetlands of China

Previous studies have suggested that, over the course of the Neolithic period, settlements in the Yangtze coastal plain gradually moved seawards and concentrated to the east of Lake Taihu, probably responding to the effects of sea-level change during the middle to late Holocene. To test this hypothesis, sediment cores adjacent to six Neolithic settlement sites across the study area were collected and analyzed for pollen and other microfossils. These records reveal details of the environmental conditions before, during and after the Neolithic occupation at each site. Results show that a freshwater marsh environment became established before each human occupation and persisted throughout and after it. There is no evidence at any site of a sudden or drastic change in environmental conditions towards the end of human settlement. After c. 7000 cal. yr BP the study area had become a wetland enclosed by Chenier ridges on the east (the southern shore of the Yangtze) and the south (the northern shore of Hangzhou Bay). During the Neolithic period (c. 7000-3000 cal. yr BP) sea level rose slowly by c. 2 m, and elevated water-tables saw the inland Taihu area become lacustrine, while to seaward on slightly higher ground enhanced sedimentation maintained freshwater marshes, fens and swamp-woodland, particularly near the Chenier ridges. These wetland-fringed coastal areas provided resources, including shellfish, deer, boar and migratory birds, that might have attracted the Neolithic communities that were abandoning their former settlement sites in the lower-lying inland area, flooded by the expanded lakes around Taihu, after c. 4200 cal. BP.