Analysis on the Characteristics and Origin of the Erosional Riverbed Landforms in the Baiyun Mountain Area of Fujian Province, China

摘要

The Chanxi, Longting and Changyang Streams in the Baiyun Mountain area of Fu'an city,China,are the streams incised in granite valleys. Numerous huge rocky holes and troughs have been developed on the riverbeds of the streams and thus are reputed to be a wonder of geosciences. The investigation has shown that the rocky holes and troughs on the riverbeds and riverside cliffs are the potholes and vertical wall-curved troughs formed by long-term water erosion of different hydrodynamic currents and rainfalls since the Pleistocene. They are the erosional riverbed micro-landforms developed in alkali-feldspar miarolitic granites. The erosion of flowing water,along with the wearing of sands and pebbles carried in eddy flows are the main exogenetic geological processes contributing to the formation of the potholes. The vertical wall-curved erosional troughs on the riverside cliffs are the products of rainfalls. The riverbeds in the Baiyun Mountain area have plenty of potholes of various types. These systematically show the erosion processes of different hydrodynamic currents and the evolution of potholes and bedrock-composed riverbeds,and therefore are valuable geological heritages.