中文摘要：

武江在粤北坪石盆地保留有6级河流基座阶地，是目前广东省内发现级数最多的阶地。阶地基座受后期风化作用影响，发育了深厚的红色风化基座。已有的河流阶地TL年代数据显示，本区风化基座的发育年代符合中国南方红土期的时牢变化规律，但其形成机制与我国红土期相应的华南地貌风化壳有别。风化基座发育受到本区构造抬升和夏季风气候的共同影响。在我国南方红色风化壳广泛发育时期，西部地区的泥石流也出现多期活动。总体上看，泥石流发育期滞后于红土发育期，且不存在红土期内多次发育的特征，这说明夏季风气候对华南地区的影响大于西部地区。红色风化壳发育和泥石流发育共同反映出夏季风气候的加强，季风区内的水循环加快，风化侵蚀更加强烈。

英文摘要：

Total six classes of rock-based alluvial terraces are discovered in Pingshi Basin of the Wujiang River, Guangdong, which are the most classes of terraces in the province. The rock-bases of the terraces affected by the chemical weathering have developed into deep-thick red weathering bases, which are special weathering crust covered by alluvium. The alluvium, as the product of floodwater, reflects the intensity of the fluviation and the summer monsoon. The development of weathering base was influenced by the tectonic rise during the mid-Pleistocene and summer monsoon together. The TL data of the alluvial terraces, including （819±57） kaBP, （694±55）kaBP, （426±29）kaBP, （ 163±11 ）kaBP, show that the development time of the weathering rock-bases in Pingshi Basin accorded with the temporal-spatial characteristics of the Red Earth Period in South China, but its formation mechanism was different from that of the weathering crusts of corresponding terraces in the area, and it was mainly affected by the regional tectonic rise. The weathering rock-bases in Pingshi Basin developed one more class of terrace as compared with other places in South China during Q^12 and Q^22, and T1 in Pingshi Basin was formed during late mid-Pleistocene, earlier than that in other places of South China. When the red weathering crusts were developing in South China, the debris flow activation in western China also came forth many periods. As a whole, not only the development periods of debris flow were later than those of the red earth, but also its frequencies were less during the same period, indicating that the effect of summer monsoon on red earth development was more intense than that on the debris flow, when summer monsoon was intensified, and the hydro-cycle was quickened and chemical weathering reinforced. The climatic environment and tectonic movement offered the possibility to develop the double-layer planation surface in Pingshi Basin. The covered weathering rock-base may be a double-layer planation surface develop