A Holocene loess palaeosol sequence at the Laoguantai site in the eastern part of the
Guanzhong Basin was studied for identifying
changes in surface hydrology during the last 11 500 years. The profile was dated with the prehistorical remains and optically stimulated luminescence techniques. Results of the studies in the field and the laboratory provide new insights into soil development and pattern of climatic changes in this area. The soil S 0 was a soil complex composed of the lower soil S 2 0 and the upper S 1 0. Two rainwash beds were
identified in the profile, whose presence in the aeolian loess in the southern Loess Plateau means that the climate was wet enough to cause active surface runoff during their deposition. They are regarded as the records of surface hydrological events during the rainy and wet phases. The first humid period identified at 9 000～8 500 a BP in the eastern
Guanzhong basin suggested that the rainfall change was evidently not in phase with the temperature change in the early Holocene. The increasing in rainfall took place later than that in the temperature. The second rainwash bed, identified at 4 000～ 3 600 a BP, was another rainy and wet period. The strength of the soil erosion and deposition was intensified by the human activities in the stage.