Abstract: The Xujiacheng site, buried in the Malan Loess overlying the second terrace of the Shuiluo River in Zhuanglang County, Gansu Province, is a significant Paleolithic site yielding plenty of archaeological materials. AMS14C dating and climatic comparisons with other sites indicate that the entire suite of assemblages date roughly from 46,000 to 25,000 calibrated radiocarbon years BP. Site formation processes such as sediment movement and trampling in relation to the stratigraphic position of cultural materials are important to understand when dating multi-level sites such as Xujiacheng. The AMS14C method was used to date this site. The four cultural layers (4A, 4B, 4C and 5) provide the following dates: (22,925±426) - (28,160±342), (41,488±378) - (42,822±451), (45,167±524) - (46,222±714), and older than 46,222±714, respectively. Comparison with climatic events as indicated by magnetic susceptibility at Xujiacheng, Zhuanglang 5, and the Dadiwan site shows that they have similar ages of the same events (such as H4 and A4) that were well dated in Hulu Cave record. With these agreements, there is more confidence in our AMS14C dates for the Xujiacheng site.
A complete high-resolution chronology is vital for accurate archaeological dating, and the Longxi Basin where the Xujiacheng site is located in is an ideal area for using different dating methods and the loess-paleosol sequence analysis. Future Paleolithic work in this area with solid control of chronology will make a significant contribution to our understanding of the interaction between human behavior and environmental change in Late Pleistocene in North China.

Key words: Xujiacheng; Paleolithic; AMS 14C; Climate; Chronology