Hominid Ages And Behavior Based On The Analyses Of Pleistocene Loess Deposits And Geomorphology In Lantian(Shaanxi Province),central China

Lantian is located in the northern foot of the Qinling Mountains,and belongs to the convergence zone of northern subtropical evergreen broad-leaved forest and warm temperate deciduous broad-leaved forest.Lantian has four distinct seasons because the climate condition here is affected by the Asian monsoon circulation.Since the Quaternary,a large amount of loess deposits is accumulated,with a great amount of evidence for human settlement from Pleistocene had been found.The Homo erectus cranium,mandible and hundreds of associated lithic artifacts were found in Chenjiawo and Gongwanglin sites in the 1960s which is one of the most significant discoveries in the field of paleoanthropology and Paleolithic archaeology in East Asia,providing the key evidence of evolution of ancient people and the development of the Paleolithic industry.However,the region,which was not adequately researched until the early 2000s(except Chenjiawo and Gongwanglin),still poses several questions regarding hominin behavior and lithic technology development,such as lacking of stratigraphic record,corresponding age data.The chronological sequence of human settlement from Pleistocene and the whole picture of Lantian cannot be comprehended due to a shortage of the research.Through years of the field investigation,our group discoveried eight new Palaeolithic open-air sites in the Lantian area of the Bahe River valley.Artifacts were found from the paleosol layers in these sites.In this paper,we investigated four loess-paleosol sequences(the Jijiawan,Ganyu,Diaozhai and Jiangwan sites)by optically stimulated luminescence(OSL),magnetostratigraphy and stratigraphic correlation.The results demonstrate that the artifacts are located within paleosol layers S4,S3,S2,and S1;and within loess layer L2 and L1.The main stone-knapping technique used was direct hard hammer percussion.In addition,the technological features of the stone tools found at these sites exhibit little variation,indicating the presence of a long-established,stable technology in the Lantian area,also indicating that a long history of hominin occupation of the region since middle Pleistocene.According to the location of these four sections and the ages of the artifacts,we believe that since the Middle Pleistocene(0.4Ma),the hominins beings had the ability to move in the relative elevation of at least 400m,and live at an altitude of at least 1000 m.Furthermore,they had the ability to cross the Hengling plateau at/before penultimate glacial.It can be seen that the geomorphological conditions of this region had no binding effect on the range of ancient human activities since the Middle Pleistocene.Combined with the Paleolithic study around the Qinling Mountains,it is found that the Paleolithic technology in Lantian and Luonan basins have similarities as well as the time range of the ancient human activities.Therefore,we presumed that the ancient humans in these two regions belonged to the same ethnic group and there might be exchange or migration between these two regions since the Middle Pleistocene.The ArcGIS software is used to analyze the digital elevation and slope data of the East Qinling area between the two regions in this article.The results indicate that there are two potential "East Qinling Channel".One of the channels may have been closed by the uplift of the East Qinling since the early Pleistocene,and the other one had the suitable geomorphological conditions that allowed the ancient humans to pass throughout the Pleistocene.