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The Northern Coast Yehliu Geopark is famous with spectacular erosional features which can resemble the figures of people, plants and animals. Those landscapes can be easily imagined through their names such as Yehliu Cape, Cuesta, Weathering Ring, Honeycombed Rock, Mushroom Rock, Ginger Rock, Concretion, Candle Shaped rock, Sea Notch, Sea Cliff, Sea Cave, Ocean Erosion Pothole, Melting Erosion Panel, Joint, Bean Curd Rock, Sea Groove, Trace Fossil, Queen’s Head, Fairy’s Shoe, Marine Bird Rock, Ice Cream Rock, Peanut Rock, Pearl Rock, etc.
Strata revealed in Yehliu is mainly bedded sandstone in Miocene age and can be subdivided into 8 units based on their lithological and morphological characteristics. In which, many sandstone beds are calcareous and rich in concretions. These calcareous sandstones and rocks burying under the stratum are hard and solid in nature, making Yehliu a place full of stunning and amazing wonders. The first layer are mushroom rocks composed of the two-meter calcareous sandstone on the top with the ocher-yellow sandstone on the bottom. The mushroom rocks can be divided into three types based on the difference appearances as displayed on the head and neck of the rock: “Thin-neck rock”,” thick-neck rock” and “neckless rock”. Due to undertaking a heavier load on the top, many of the thin-neck mushroom rocks may be toppled down easily if striking by earthquake or violent winds and waves. The top part of mushroom rocks with the differential erosion caused by weathering make the surface of rock turns into the shape of honeycomb or window lattice; whereas the flat, level rocks are spreading across the land and covered with holes of different sizes. The most famous mushroom rock scene in Yehliu is the Queen’ Head formed due to the differential erosion caused by seawater during curst movement. When comparing the height of which with the crust’s rising rate, it is estimated that the age of the rock is about 4,000 years old. The “Queen’s Head” has been titled since 1962-1963 after the top of the rock being fallen apart the rock has its likely shape of the face of Queen Elizabeth I. However, with the constant devastation of sun, rain and wind as well as humankind’s activities, the Queen’s Head is narrowed down and at the brink of collapsing.
The second is the layer of ginger rock which is composed of irregular sandstone on the top with ocher-yellow sandstone on the bottom. The interweaving patterns as shown on the surface of ginger rock are the result of crust extrusion occurred underground. These patterns as shown are called “joints” in Geology. The name “Ginger Rock” titled because of their rough surface and the beige tint as appeared. The rock layer containing ginger rock in the area is about 50 cm of thickness. The ginger rock landscape spreads from North-East to South-West of the cape in a band distribution manner and is available on the sea cliff and the wave-cut platform.
The third is the layer of candle shaped layers consisted of globe lumps contained within the sandstone. The name of candle shaped rock is formed because of its shape like a conical rock standing erectly on the ground. It is about 0.5~1 cm in diameter with the top being narrower than the bottom. A round shape concretion containing lime is formed on the central top of the rock and being surrounded by circular grooves, just like a candle tray.
Yehliu is located in the subtropics zone with a temperate and humid climate. The annual influences of Northeast monsoon and wave erosion are for over a six-month period. This condition makes weathering can be detected apparently on the rocks, meanwhile the formation of strange rock landscapes is also due to the decomposition of the special rock layer as existed underground. Consequently, weathering and weathering rings are common landscapes found in Yehliu.
The coastal process on faults or joints is also presented with many other landscapes like Sea Groove which is formed as a result of sea wave’s splashing, eroding along the surface of the joint of the rock layer. Besides, close-type joint formed when the raindrop goes deep into the rock layer and dissolves part of the chemical or mineral substances inside the rock, while the rock is exposed to sunlight and thus leading to the formation of the weathering ring as the dissolved substances being settled around the concretions. Bean Curd Rocks formed by seawater flows and erodes along two groups of concretions interwoven vertical to each other are found commonly in the Northwest of Yehliu.