Abstract: The Wulanmulun site, found in 2010, is the first important new Paleolithic site discovered in the Ordos Plateau since the 1920s when Salawusu (Sjara-osso-gol) and Shuidonggou (Choei-Tong -Keou) sites were discovered. After several excavations during 2010-2012, more than 13,000 stone artifacts and 15,000 mammalian fossils were discovered. Research involving multiple disciplines has been carried out and interesting results can be anticipated very soon. A recently dating result for the site is 65~50 ka BP by OSL and 14C-AMS (Personal communication with Zhang Jiafu). As part of the program, this paper reports on the refitting analysis of stone artifacts from different archaeological layers of the site, and what this implies for understanding the formation processes of the site. Among 11934 pieces of stone artifacts from the excavations of 2010~2012, 28 refitted groups have so far been identified from the 8 layers at the site, involving 64 stone artifacts, including 4 cores, 9 flakes, 49 broken flakes, 1 chunk, and 1 retouched flake from layers 6-8. This indicates a refitting success of 0.53% of the entire lithic assemblage. The raw materials of the refitted lithics were mostly colored quartzite (53), with fewer pieces of white quartz (4), grey-white flint (4) and red-white sandstone(3). Except for layer 7, examples of refitting occurred in each cultural layer. Most were from layer 2 with 16 groups of 35 pieces of stone artifacts. Four groups with 9 pieces were from layer 5, three groups with 6 pieces were from layer 4, two groups with 4 stone artifacts were from layers 3 and 8, and one group with 6 pieces were from layer 6. Two approaches were applied in the present study to studying different patterns of refitting. One is the pattern of conjoin, which indicates refitting relationships between cores and flakes (including modified flakes, debris and chunks), and between flakes and flakes (including debris and chunks). These conjoins mainly reflect activities involving the specimens before they were buried. The other approach examined refitting relationships between incomplete flakes and chunks that occurred after the burial of the specimens. With regard to site formation processes, the products of conjoined patterns resulted from different procedures of flaking in a definite sequence. However, the products of joins between incomplete flakes and chunks occurred at the point of fracture. Distinguishing these different patterns is not only significant for the studying site formation processes, but is also important for studying the technology for making artifacts, and the nature and function of the site. At the Wulanmulun site the join pattern of refitting forms the majority of refitting with 22 groups (78%). The other are 5 groups of conjoin pattern and 1 group of both. From analysis of the spatial distribution of material at the site, all horizontal and vertical data results indicate fast deposition without later disturbance. Because most refits result from individual flaking sequences, this suggests that this Middle Paleolithic industry was formed in situ.

Key words: Ordos; Wulanmulun site; Stone artifacts; Refitting; Middle Paleolithic