The Impact Of Climate Change On The Evolution Of Civilization In The Ordos Plateau During The Mid-Late Holocene

The Ordos plateau is located in the monsoon marginal zone in north China,which is both influenced by the western inland arid climate,and also affected by the eastern monsoon humid climate;it presents the biological transition scene of the forest grasslands,semi-arid and arid grasslands,and arid desert grasslands.The desert within the plateau is inlaid with the sand land,and a good transition zone has been formed with the east loess plateau,this has given birth to the inlaid farming and animal husbandry occupational patterns in this area.The special geographical location has created a fragile ecological environment patterns,and this region has always been an ideal area for the ancient climate research.Ordos plateau is one of the cradles of human civilization,early humans are greatly influenced by the environment,the discovery channel and basis has been provided for the rise and fall of Ordos culture by the ancient climate study on the Ordos plateau,the information on the climate has been more provided for the environment evolution of Ordos,which is helpful for the in-depth understanding of the rise and fall of civilization,the impact of climate change on the evolution of the environment and the development of human civilization is explored.This study has systematically analyzed the environmental magnetic parameters,chroma,CaCO₃ content and grain size of the Zhaishan Shicheng section?ZS section?and Zhaimao section?ZM section?on the eastern edge of the Ordos plateau,and the sediment characteristic rules in this area are explored.Based on the AMS ¹⁴C dating method and previous studies,a chronological framework is established for the ZS section,so the climatic evolution history of Ordos plateau 7000-1500 a B.P.?B.P.is the era from now"1950 A.D."?has been reconstructed.This paper makes a detailed exploration of the Ordos plateau civilization evolution history,classifies and summarizes the relic sites,the influence of climate change on the evolution of civilization has been discussed by comparing the history of climate evolution,and the following conclusions have mainly been obtained:?1?The magnetic minerals in the sediments of Ordos plateau are mainly the ferrous magnetic minerals,and contain a certain amount of incomplete antiferromagnetic minerals,the magnetic minerals have a low concentration and a coarser particle size,and the magnetic minerals are mainly the multi-domain?MD?,pseudo-single-domain?PSD?and coarse-grained stable single-domain?SSD?.The variation of CaCO₃ content in this region follows the law of leaching-deposition.The grain size index indicates that the sediments in the east margin region of Ordos are coarser in particle size,and mainly consist of sand content components.?2?The ZS section has revealed that the climate evolution of 7000-1500 a B.P.in the Ordos region go through mainly the following five stages:The climate of7000-6000 a B.P.is humid,and the summer and winter monsoons change in the same phase,both of which tend to gradually weaken.The summer monsoons are still strong,and the climate is still suitable.The climate of 6000-5000 a B.P.is relatively dry,and the winter and summer monsoon indexes fluctuate steadily at low values,the wind dynamics,precipitation and soil vegetation development are weaker;the climate of5000-4500 a B.P.is relatively dry,and the whole winter and summer monsoon is at a high value,and is featured with strong fluctuations,the winter monsoon change more violently,having shown the dynamic effect of two strong winds;the climatic conditions of 4500-3500a B.P.are relatively humid,and the summer monsoon index is at a high level on the whole,while the winter monsoon index is at a low level on the whole;the climate of 3500-1700 a.B.P.is dry first and then wet,and the fluctuation of summer monsoon index is relatively stable,with a trend of decreasing first and then rising,the winter monsoon index has shown an increasing trend since 3500-1700a.B.P.?3?Within the research period,the evolution of human beings and human being social civilization is influenced by many factors,among which the climate change plays an indispensable role.During the Yangshao period?7000-5000 a B.P.?,the human civilization in the Ordos plateau region is influenced by various types of Yangshao culture in the central plains,resulting in a long period of cultural exchanges and integration,which is inseparable from the warm and humid climate;During the Longshan period?5000-4000 a B.P.?,the stone ancient town belt appears with the frequent wars and the changes in the occupational pattern,which are all related to the unstable climate,and cold and drying events in this period.During the bronze and iron age?4000-2171 a B.P.?,the nomad tribes occupy the Ordos plateau,many rock paintings and tombs have shown the occupational pattern of transformation from agriculture to animal husbandry,which correspond to the dry and cold climate change in this period.During the Qin and Han dynasties?2171-1730 a B.P.?,the central plains dynasty is able to successfully implement the system of prefectures and counties in Ordos and vigorously develops to open up wasteland,which is also supported by the warm and humid climate.