Abstract: Danjingkou reservoir is the source of water for the Middle Route Project of the South- to-North Water Diversion in China. It is adjacent to the Qinling Mountain in the North and Daba Mountain in the South, with the reservoir fed by the Hanshui River. During the Pleistocene, this area had a stable subtropical environment with abundant plant and animal resources suitable for hominid subsistence. This is a pivotal area for human migration and cultural communication between south and north China. The discovery of hominid fossils, such as Xichuan Man, Yunyang Man, Meipu Man, Yunxian Man, and abundant Paleolithic sites in this area highlight its significant position in the Paleoanthropology and Paleolithic archaeology of China.
To cooperate with the construction of the national South-to-North Water Transfer Project, the field team of IVPP (Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences) conducted two surveys around the margin of the Danjiangkou reservoir in 1994 and 2004. Nine-one Paleolithic open-air sites were discovered, and some heavy-duty tools, like picks, handaxes and cleavers with Acheulean technological characteristics were also collected. In 2006, this team began excavations on some key sites, and Guochachang II was identified as an Early Paleolithic site. It was first discovered in 2004 and excavation conducted in April and May 2009. It is located on the left bank of Hanshui River’s third terrace. The excavation exposed an area of 500㎡ and uncovered 132 stone artifacts in situ. The typology and technological analysis of these stone artifacts reveals that:
1) Lithic raw materials exploited at the site were locally available from ancient river gravels. Four kinds of raw materials were utilized: quartz, siliceous limestone, tuff and sandstone. Quartz is dominant for hammerstones, cores, flakes and chunks (85.45%). For the various tools, scarpers were predominantly made on quartz (76.92%), but the heavy-duty tools mainly employed siliceous limestone and tuff (88.89%).
2) The excavated lithic assemblage includes hammerstones (9), cores (14), flakes (69), chunks (18), and stone tools (22). Stone tools include scrapers (13), choppers (5), picks (1), and handaxes (3).
3) The principal flaking techniques are direct hard hammer freehand percussion and bipolar percussion. Meanwhile, the anvil technique (struck against an anvil) was possibly used also. Flakes struck with the anvil technique are large in size, with heavier weights and large platform angles, compared with the bipolar and freehand flakes. Freehand cores (85.71%) and bipolar percussion cores are dominated by simple core reduction strategies (single and double-platform cores=75%), and the multi-platform cores comprise 25%.
4) Scrapers mainly employed small flake blanks (<50mm), with minimal unifacial retouch. For the heavy-duty tools, large cobbles were the predominant blank for choppers and picks. However, all the handaxes were made on large flakes with bifacial shaping.
5) There were three different methods for the tools making in the site: 1) a reduction sequence for small-sized flakes and light-duty tools; 2) a sequence of making heavy-duty tools based on large- sized cobbles; 3) and the production of large flake blanks for heavy-duty tools.
The cultural layer is a red clay which can be generally divided into two parts, a upper layer with calcareous nodules and a lower layer of grey-white vermiculated soil. The development of red clay in this region did not reach the stage of a laterite formed in the advanced weathering process of desiliceous and enriched bauxite, associated with the formation of gibbsite in Guangdong and Guangxi provinces. Instead, it corresponds roughly to the red soil weathering crust stage in southern China. The Middle Pleistocene was the optimum weathering period in southern China when the northern limit of the red soil weathering crust extended south of the Qinling Mountain. The survey area is located in the northern limit of the red soil weathering crust, its age should fall within the optimum period of the development of the red weathering crust and the study of the loess-paleosol sequence showed that paleosol S4-S5 was an intense humid-warm stage in the Middle Pleistocene correlated with MIS11-MIS15. Based on the geomorphology and the nature of the sediments, we suggest that the date of the site should be close to the S4-S5 in the loess- paleosol sequence, with a geological age belonging to the Middle Pleistocene.
The study on the Guochachang II site provides us very important material for understanding the early Paleolithic culture in the Danjiangkou reservoir area, and exploring the adaptive strategy and the behavioral pattern of the early humans who lived in the Danjiangkou reservoir area.

Key words: Danjiangkou Reservoir Region; Guochachang II site; Stone artifacts; Handaxes; Middle Pleistocene