Dahua Gourd Cave Introduction
The valley terrain of the Keelung River features many smooth potholes, known as "potholes" in geology, located between Pingxi Station and Sandiaoling, in addition to waterfalls. The formation of potholes is due to the uneven structural hardness of geological rock layers, which are eroded by river water carrying fine sand, creating depressions. Subsequently, small whirlpools form inside these depressions, leading to further erosion and the development of pot-shaped small caves. Potholes typically appear in the concave, turbulent sections of meandering rivers where the riverbed consists of exposed hard rock. The Dahua Pothole Group, located below Dahua Station, is the most dense and observable area, showcasing almost all types of potholes due to the interaction between water flow and rock layers, making it a natural geographic classroom.
