Acidic Volcanic Rocks, High Island

High Island is located in southeastern Hong Kong and features the “High Island Supervolcano,” which is the first ancient supervolcano discovered in Hong Kong and southeastern China. Over 100 million years ago, a massive amount of acidic lava, accompanied by scorching volcanic ash, erupted from deep underground, blotting out the sun and covering over 1,000 square kilometres of land in Hong Kong with an accumulated thickness exceeding 1.3 kilometres. As this vast expanse of volcanic lava slowly cooled, and through tens of millions of years of weathering, marine intrusion, and wave erosion, it ultimately shaped the peculiar geological landscapes seen today around Hong Kong’s Ninepin Group, High Island, and Sai Kung. The upper part of this extinct volcano consists of volcanic rocks, extending from High Island to the Ninepin Group and covering a large area of land within the Sai Kung Volcanic Rock Region. The volcanic ash erupted from the volcano solidified into magnificent rock columns, such as tilted hexagonal pillars and curved rock walls, allowing Hong Kong to rank among world-class geopark cities. The hexagonal rock columns were consequently chosen as the emblem for the Hong Kong National Geopark, and the High Island Scenic Area was voted by visitors as the top choice among the “Ten Scenic Spots of Hong Kong.”