Dahua Hot Spring Cave Introduction
The valley landscape of the Keelung River, apart from its waterfalls, features many smooth depressions known as "potholes" found on the riverbed between Pingxi Station and Sandiaoling. Potholes are formed due to uneven structural hardness of geological rock layers, which are eroded by river water carrying fine sand, creating depressions. Subsequently, small whirlpools form within these depressions leading to further erosion, resulting in pot-shaped cavities. Potholes typically appear in the concave bends of meandering rivers where there are numerous eddies and rapid flows, with the riverbed exposed to hard rock. The area below Dahua Station, known as the Dahua Pothole Group, is the most concentrated and observable location where almost all types of potholes can be seen as a natural geographic classroom resulting from the interaction of water flow and rock layers.
