Taiwan is formed from the converging oceanic Pacific plate and oceanic Philippines plate. When the two oceanic plates converge, the denser plate subducted under the less dense one. A subduction zone was formed and created a deep oceanic trench. The friction between the two plates causes the crust and mantle to melt, rising through the mantle and crust to eventually form Taiwan. Due to this, a volcano (now dormant) was formed. In Yehliu park, there are traces where lava flowed and hardened, as well as many pieces of basalt rock lying around from the Pacific plate.
Yehliu park contains many unique geological formations, such as “Queen’s Head”. It is located along a cape stretching out from the town of Wanli. The cape stretches around 1,700 meters, formed as thousands of years of geological movement forced the mountains to change their shape, jutting out into the ocean. There are other popular formations such as Sea Candles, Fairy’s Shoe, Ginger Rocks and Princess’ Head.
Joints are a discontinuity where the rock can be more easily eroded by water and air as these natural elements can move more easily through these joints, thus increasing the rate of weathering. A joint is a fracture caused by compression or tension in those rocks. As certain rocks are densely jointed, the joint will be fragile. Joints present in the rocks are a significant part of Yehliu park, as they help form what it is today. These joints aid natural processes, as well as produce different landscapes such as sea caves, chessboard rocks, and weathering rings.
Sea-eroded caves and platforms are formed by wave erosion, where a constant wave attacks the same location over a long period of time, resulting in these marine platforms. Some of these marine platforms may be subjected to tectonic uplift that leaves them far above the beach after the sea level falls, giving us a good indicator of sea-level change.
Appearing on the wave-cut platforms, marine potholes are a large part of Yehliu park. . These potholes will become larger and deeper over time due to being continuously eroded and incised by pebbles brought by waves. Inside these potholes grow many seaweeds, small fossils and small crabs.
There are many fossils such as the sea urchin fossil, as well as fossils to show the trace of the crabs’ motion such as the sand pipe fossil, which is a type of trace fossil the presence of fossils show that Taiwan was once submerged in the ocean.
Composed mainly of sedimentary rocks, due to it being by the sea, the sea water eventually erodes away the softer rock layers while those hard and solid layers may therefore turn into sea capes eventually (Candle Rock)