Shimen Cave Introduction
Shimen Cave, standing along the coastal highway Provincial Highway 2, is a prominent landmark in the Shimen District of New Taipei City. The name comes from this cavern, which amazed the Japanese during the colonial period due to its unique coastal erosion landscape, leading them to name the area "Shimen Village," a name that has continued to be used in local township names to this day. In geological terms, it is formally known as a "sea arch," formed by erosion from seawater. Millions of years ago, the Datun Volcano Group erupted, accumulating thick layers of volcanic debris and lava. Over time, heavy rains washed these materials, forming layers of rock along the coastline and creating a small hill. With further geological pressure, vertical "joints" or fractures formed, and the northeast monsoon along with frequent summer typhoons generated strong wave action, providing substantial erosive energy. The seawater has progressively worn away the layers along the joints, causing pieces of rock to crumble into the sea. Over time, this transformed from an initial sea erosion gully into a sea cave, eventually evolving into the sea arch we see today. Although formed by erosion, Shimen Cave is notably elevated above sea level, due to recent tectonic movements that have uplifted the ground, making it over ten meters above sea level, a testament to geological changes. If you venture further into Shimen and observe closely, you can see clearly stacked layers of rock, each containing fine sand, volcanic debris, and gravel of varying sizes mixed together. This indicates that the initial accumulation of rock layers was likely due to landslides caused by heavy rains, where fast-moving debris carried down various sizes of stones and fine sand that piled up at the base of the mountains without settling individually, resulting in the mixed layers of fine sand and gravel seen today. In terms of natural ecology, upon entering Shimen Cave, you are greeted by stunning views of the sea and sky. Although there’s only a small beautiful shell beach here, it often reminds one of Kenting. In the shallow coastal waters among the reefs, there are numerous schools of fish and hermit crabs. The coastal rocks, adorned with seaweed, present a vibrant green view, and sometimes local residents can be seen collecting algae. Following the coastal path and observation platforms leads to even more expansive sea views. Between April and May each year, native species of lilies and stone vegetables bloom, decorating the top of Shimen Cave and creating a spectacular sight. A trip to Shimen Cave showcases diverse ecosystems and reveals the rich landscape along the Shimen coast.
