Research On The Environmental Archaeology Of The Yujiashan Site In Hangjiahu Plain

Yujiashan ruins are located in Yuhang district, in the northeast of Hangzhou in Zhejiang province. Here for the first time discovered ring trench with clear settlement structure of Liangzhu period, and includes the sedimentary strata of all the Liangzhu culture period. So it has extremely important significance for studying the evolution of the climate and environment through the Liangzhu culture coupled with human activities. This paper mainly uses the AMS14C dating, quaternary geology, geomorphology and other analysis methods to reveal the climatic and environmental changes before and after the period of Liangzhu culture, and then through the changes discusses the causes of base level of life and climate evolution of Liangzhu period. It also discusses the disappearance of Liangzhu culture and many other questions. The conclusions are as follows:(1) Yujiashan ruins are situated in Hangzhou-Jiaxing-Huzhou plain, near the East China Sea and its terrain is relatively flat. The sediments layers from top to bottom is divided into:anthropogenic interference soil layer (0-1.2m), the Rhubarb soil (1.2-2m), Liangzhucultural layer (2-3m) and the immature layer (3m-). Though point elevation measurements of the hangjiahu plain ruins, we can find that the highest water level of east-shao creek is higher than plain surface about2-3m, which has some associations with the sudden disappearance of Liangzhu Culture.(2) Here the depth of Liangzhu culture layer is about2-3m, and in some places there will be deposited faults. In this layer, people discovered the Liangzhu cultural sites and typical ring trench structure. Explored cultural relics indicate that here include the complete history of Liangzhu culture. By dating and ancient environmental indicators, we can find that in terms of climate, Liangzhu ancestors experienced a process of cold and dry to warm and humid, then to cold and dry in 4800～4000years or so ago.(3) In the formation process of the raw soil of Yujiashan (about5000years ago), the type of climate experienced an evolution from cold and dry to wet. And through the analysis of the field bedding and the particle size clay minerals index, we can find it belongs to typical tidal flat deposits. This is different from the raw soil near Liangzhu ancient city.(4) In Yujiashan region, the yellow soil directly coated on the cultural layer and experienced a process of serious floods in early time (the same as the late Liangzhu culture climate type) to fade in the late time. In addition the average particle size in the cultural layer is thicker than that near the ancient city, and the particle size distribution and magnetic parameters and other indicators were different, indicating that the deposition power is relatively large and may be subject to the eastern sea water intrusion caused.