Research On Geomorphic And Sedimentary Basis For The Neolithic Liangzhu City Within The Hangjiahu Plain

The area of the Neolithic Liangzhu City is located in the south of Tai lake, Hangjiahu plain. The city site was founded in Town Pinyao, Yuhang district of Hangzhou city, the centre of which is the famous Mojiaoshan Site. According to previous field observation and researching, five layers of soil from the earth’s surface down exit widely in this area, in which the fourth layer of soil is named raw soil. The layer of raw soil is the "stage"of Liangzhu Culture because of underlaying the layer of Liangzhu Culture soil. The article will analyze culture development’s reason, the geomorphological information and evolution regulation of the raw soil, to discuss the results that natural geography conditions constraint culture development by multi-index such as AMS14C dating, Sedimentology, Environmental Magnetism, Mineralogy, Micropalecology. That researching method is currently rare. Researching holes were drilled in Mei Rendi, outer of the Neolithic Liangzhu City, and Gaoting in the eastsouth of the Neolithic Liangzhu city. Primary conclusions are as follows:(1) According to experiments’data of Mei Rendi Gaoting, associated with field observation, the fourth layer of soil in the holes can be divided in4sections:4a-4b-4c-4d. Foraminiferas found in section4d and4c in holes of Mei Rendi and Gaoting comfirm transgression reached maximum scale at7,000—6,500aBP. The area of Mei Rendi and Gaoting is the deadline of south and west Hangjiahu plain of transgression. Hence, the sea level never reached here.(2) Geomorphological change of Mei Rendi and Gaoting area during Mid-Holocene is as follows:transgression reached maximum scale at7,000—6,500aBP and the area was in estuary environment. Then the sea level declined to current level and kept stable, although slightly fluctuating. Large scale of terraces here were drawned by shallow sea water, the environment was tidal flat and shallow lagoon. From then on, the climate became warmer and warmer, wetter and wetter. The absolute sea level increased, but the sedimentary effect in this area was stronger than the degree of sea level’s increasing. Finally, the relative sea level still declined, this area never experienced large sale sea interruption again. The area evolved from tidal flat and shallow lagoon to limnetic plain.(3) In the early period of Liangzhu Culture, the ancient chose high terraces (for example Mei Rendi,4a:3.85Wusong Elevation) in this area, to inhabite, flourish, which are beneficial for the ancient to get used to transgression and regression environment. The sites of late period of Liangzhu Culture appear the trendency to low land. Meanwhile, the rice argriculture in Liangzhu period was also boomed rapidly, based on good geomorphology condition.