Preliminary study on morphology features of karst in the lower reaches of Wujiang River — A case in Wulong, Chongqing and the surrounding area

The geomorphology is typical subtropical karst Middle Mountain and gorge with characteristics of large scale karst gorge, natural briddge, tiankang, cave and underground river as well as colorful second deposits at the lower reaches of the Wujiang River. The karst individual feature and feature complex on stratified relief plane are analyzed and the evolution of the karst morphology at the lower reaches of the Wujiang River is studied in the paper. It is believed that 1) the stratified relief plane can be divided into 2 grade planation surfaces, 1 grade corrosion surface, 5 grade horizon karst caves and 3 grade terraces; 2) there are obvious different karst feature among different period of planation surfaces, such as the surface is integrated with lower peak cluster and karst basin and depression on the Exi Surface, but the karst feature changes in different areas on the Shanyuan Surface, which is dominated by peak cluster and gorge above the knick point and cone karst peak cluster and deep depression landscape with relatively integrated surface below the knick point; yet on the Pendi Surface, the morphology is dominated by peak cluster and uvala as well as valley; 3) the karst morphology once experienced 3 period s of evolution as the Exi period, Shanyuan period and Pendi period as well Xiagu period, which leading to the formation of the Exi and Shanyuan karst planation surfaces and the Pendi corrosion surface as well as the Xiagu gorge.