Abstract: The Sumiaoyuantou locality in Gansu Province was discovered during archaeological survey. Thousands of lithics are distributed in a lens of 1.3m long and 0.13m thick in the Malan loess on the first terrace of the Zhangma River. An assemblage of 2318 fragments of artifacts was obtained by collecting from the profile(2166) and surface(48) in 2002 and 2004, only 2214 of which are reported here. This assemblage is dominated by flakes, shatters and debitage with a few cores and tools. The stone tool technology employed in this locality is mainly bipolar percussion,plus little edge percussion. The main raw material is quartz cobbles from the modern riverbed or the bottom gravel layer. Radiocarbon dates and paleoenvironmental reconstruction shows that the climate changed much during the period 30-15ka BP in the study region. From 30ka to 24ka BP,the climate was warm and humid due to a strong summer monsoon. From 24ka to 18ka BP, it became dry and cold with a decrease in the summer monsoon and an increase in the winter monsoon. From 18ka to 15ka BP, the climate ameliorated a little with the slightly recovered summer monsoons. Sumiaoyuantou represents the late Paleolithic culture in this region, with human activity occurring at the coldest and driest time, the Last Glacial Maximum, 24-18ka BP, which may suggest the high adaptative ability of humans.

Key words: Sumiaoyuantou; Late Paleolithic Archaeology; Environmental change; Last Glacial Maximum(LGM)