MIDDLE HOLOCENE SEAWATER INTRUSION AND HUMAN’S RAPID RESPONSE IN THE YAOJIANG-NINGBO COASTAL PLAIN, CHINA

Yaojiang-Ningbo coastal plain (29°35'~30°10‘N, 120°55'~121°58‘E) is the core distribution area of Neolithic Hemudu culture. A large number of previous archaeological and paleoenvironmental researches are favorable for exploring the human-environment relationship over the past 7000 years, especially the causes of Neolithic cultural interruptions in this region. In this paper, we carried out the detailed studies on the stratigraphic records of a profile ca. 172 cm deep obtained from the Neolithic Yushan site (30°02‘N, 121°33‘E) and a spatial comparison of stratigraphic records in the region. Combined with the spatial and temporal migrations of ancient human settlements during the period from the first phase of Neolithic Hemudu culture to Shang and Zhou dynasties, we summarized the marine intrusion events and analyzed its linkage to the cultural interruptions in the evolution of Neolithic cultures in the Yaojiang-Ningbo coastal plain. The preliminary results are as follows. First, there are obvious variations in the stratigraphic records preserved in different profiles, which are distributed at the foothill and open plain at the Yushan site. It is thus necessary to compare profiles derived from different paleogeographic positions to obtain more informative paleoenvironmental evolution processes. Secondly, the Neolithic Yushan site has recorded two major seawater intrusion events, which occurred during 6300~6000 cal.a B. P. and 4500~3400 cal.a B. P., respectively. These two events had a good correspondence with the natural sedimentation layers formed between cultural layers or the absence of cultural layers at many Neolithic sites in the region. In addition, some other sites in the study area also show signs of seawater intrusion at 5400~5300 cal.a B. P. Thirdly, the spatial and temporal distributions of ancient human settlements changed at several stages. During the first and second phases of Hemudu culture, the number of sites was small and increased little, and the sites mainly distributed at the foothills, reflecting the limitations of land resources caused by seawater intrusion. The number of sites increased significantly and the sites spread to the open plain in the third and fourth phases of Hemudu culture, indicating the expansion of new lands and associated rapid human colonization due to the relatively stable sea level at this stage. At the terminal stage of Liangzhu culture, the number of sites reduced greatly and recovery didn’t occurred until the Shang and Zhou dynasties, reflecting that the long-lasting environmental deterioration induced by seawater intrusion restricted the intensity of human activities at that time. The spatiotemporal migration pattern of the sites mentioned above reflected the rapid response of the ancient human societies to the coastal environmental change.