Houtong Coal Mine探險洞穴 Introduction
The potholes of the Keelung River are a world-class geographical feature, generally found in the upper reaches of rivers. Potholes are formed by the drilling action of strong vortices carrying sand and gravel against the riverbed. Over time, as the water flow rotates these materials, circular holes known as potholes are created. Between Houdong Station and Sandiaoling Station on the Pingxi Railway branch line in Ruifang District, the riverbed of the Keelung River cuts into the hard Nuan Nuan sandstone layer, resulting in many smooth depressions on the rock surface, geomorphologically referred to as potholes, thus creating the scenery of the potholes in the Keelung River. Ruifang’s Houtong is the easiest place to appreciate these potholes. From the Wengzi Pond Bridge, located outside the Houtong Coal Mine Museum Visitor Center, visitors can walk approximately 1,700 meters upstream along the stepped embankment, taking about 30 minutes one way, to see the local potholes, known as “the dimple of stones” by the residents of Ruifang. Additionally, after exiting Houtong Station, visitors can also walk along Houtong Road upstream along the Keelung River to view the pothole scenery.
