The Geomorphology And Environmental Factors Of The Rise And Fall Of Shijiahe Culture

The Neolithic civilization existed in the Yangtze River valley and the Yellow River valley,together they formed up the cradle of the Chinese culture and played an important role in the evolution of the Chinese civilization.As an important stage of early civilization evolution in the middle reaches of the Yangtze River,the study of Shijiahe culture also plays an important role in exploring the origin of Chinese civilization.In the early stage of data arrangement,this thesis has a certain understanding of the cultural evolution sequence of the whole Shijiahe culture development from Chengbeixi culture to Shijiahe culture,based on the preliminary statistics of the distribution of sites in different cultural periods,it is concluded that the Shijiahe culture distributed in a belt along the the hilly region of the Northern Jianghan Plain.Based on the field investigation in the early stage,the macro-geomorphologic features and micro-geomorphologic units of the Shijiahe site were comprehended in detail.The section of Tan Jialing site and the section of Sanfangwan site,which can cover the whole period of Shijiahe culture,are selected,to establish a more accurate absolute chronological framework of the Shijiahe culture,and to compare and analyze the grain size,sporopollen,magnetic susceptibility,phytolith and geochemistry of the sediments in the profile,by analyzing the paleosedimentary environment of the site,the paleoclimate change law revealed by the Climate Proxy Index is obtained,and the paleoclimate of Shijiahe culture period is reconstructed.This is of great help to the study of the interactive response relationship between environmental change and civilization evolution.In addition,the relationship between the water system around the remains of ancient Shijiahe city and Beigang Lake has been restored through detailed geological drilling of important nodes around the ancient city of Shijiahe,and a certain understanding of the water environment around the ancient city has been obtained.Through the analysis of the phytolith in the Shijiahe site area,the food composition model of the Shijiahe culture period,in which rice cultivation was the main form of agriculture,supplemented by wild food resources,was obtained,which made the relationship between the development of the Shijiahe civilization and climate change more closely.The results show that:The cultural relics between different cultural layers unearthed from the sections of Tanjialing and Sanfangwan Relics,as well as the overlapping relationship between different cultural layers,can reflect that the two sites have a complete sequence of Shijiahe culture;at 3.8-2.8 m for the late Qujialing culture,2.8-1.25 m for the Shijiahe period,and 1.25-0.45 m for the post-shijiahe period,it is reasonable to regard 3.8 m in Tan Jialing section as the time when Shijiahe culture began in this section,The results of four ages show that the absolute age frame of Shijiahe culture is between 4900-4100 cal.a BP;The Sanfangwan section is at 1.3m,which is equivalent to the early stage of Shijiahe culture.The results of three ages show that the absolute age frame of Shijiahe culture is 4850-4100 cal.a BP,so the absolute age frame of Shijiahe culture can be set at 4850-4100 cal.a BP.(2)Through the analysis of sporopollen,grain size and magnetic susceptibility of Tanjialing section and the comprehensive analysis of sporopollen and geochemical elements of Sanfangwan,5600 cal.a BP,woody plants were relatively prosperous.This period was dominated by coniferous and broad-leaved mixed forest and grassland landscape,but forest landscape accounted for a large proportion,indicating warm and humid climatic conditions,which was considered as the Holocene Great Warm Period.5600-4800 cal.a BP,herbs plant dominated,Gramineae and companion plants gradually increased the response to this phase gradually dry trend,human activities began to intensify,rice farming began to flourish.4800-4100 cal.a BP,the climate is relatively turbulent,and it is further dried.(3)A comparative analysis of the rice-type phytolith of Tan Jialing section and the rice-type phytolith that has been domesticated in the laboratory shows that the rice of the Shijiahe culture period has been domesticated by the ancients,the plant remains of Shijiahe site show that the main food in this period was mainly cereal grains and mainly rice-based agriculture,and the wild plant resources were not fully utilized,but also had some collecting activities,the records of rice phytolith indicate that the ancient people experienced the most prosperous period in the middle Shijiahe period,and then gradually made the culture decline because of the decline of rice farming caused by the drought.(4)Based on the analysis of the characteristics of the sediments from the Luoyang spade borehole,and combined with the ancient geomorphology recorded in the local county records,the northern part of the site consists of the slope of Jingshan,Huangjiashan and Yanjiashan,and the southern part of the ancient city,Shibanchong,forms the northern boundary of the ancient Beigang Lake,east and West Rivers pass through the ancient city respectively and pour into Beigang Lake.The outer wall and ring moat of the ancient city play a certain role in the irrigation of the land and the resistance to flood and foreign invasion.(5)Combined with the climatic proxy indexes of Tanjialing and Sanfangwan sites,stalagmites and peat in the surrounding areas of Jianghan Plain have revealed that4200 cal.a BP the civilization of Shijiahe Culture in the Jianghan Plain declined and left the ancient city abandoned.