Analysis of stratigraphy on multi-profiles in the Taihu Lake region and paleoenvironmental events in the Liangzhu culture epoch

Abstract

The Shahe profile in Dongling,Liyang,the Caoxieshan site in Weiting,Suzhou and Maqiao site in Maqiao town,Shanghai are chosen as the major research objects on stratigraphy,from which we analyze and study the paleo-corroding surface,deposit characteristics,sporo pollens,chemical elements,14C dating and climate transformation curve transformed by chemical composition from the stratum of the Maqiao site in Shanghai,combined with the analysis of the regional paleoenvironment and environmental archaeology as well as the research results of the temporal and spatial distribution of archaeological sites since the Neolithic Age in the Taihu Lake region.The research results indicate that the climate of Liangzhu epoch in the Taihu Lake region increasingly changed towards colder and drier than that of its former time in Holocene Megathermal period,however,much more time of it was still warmer and wetter than today.In the end of Liangzhu epoch,the climate was at the lowest position and showed rapid and violent fluctuation,which matched well a long time course of sea-level falling that was reflected by the paleo-corroding surface of Liangzhu epoch.The flood accumulation layers,the buried ancient trees,the buried archaeological sites and cultural interruption,etc.prove the existence of the ancient floods;the iron manganese concretion and the ancient wells under water such as the Taihu Lake,Chenghu Lake and the Taishidian in Zhouzhuang etc.today reflect on the dry periods or drought events.The background of Liangzhu cultural development was that the sea-level in the Taihu Lake region was slowly falling,the area of fresh-water lakes and marshes were increasingly decreasing,which made the land increasingly exposed;in the meantime,the climate was slightly better than that of today.In 4300-3800aB.P.,the low sea-level,the abnormal climate as well as the frequently occurred floods and droughts were the environmental background of Liangzhu culture towards the decline and fall.We think that the direct reason for the decline and fall of Liangzhu culture is more complicated than we have imagined ever,however,the frequently occurring floods and droughts as well as the abnormal climate should be seriously fatal hit for Liangzhu people living on the paddy growing,fishing and hunting.