High Island Reservoir's East Dam is one of the most popular sites at Hong Kong Geopark. It is home to some spectacular natural wonders: hexagonal and S-shaped columns, and sea caves.
Guide San Cheung Tit-sang gave nine Young Post junior reporters an exclusive tour, during which he talked about the reservoir's geological history, rocks and landforms. Here the junior reporters share their insights.
Amazingly, in the teeming metropolis of Hong Kong, an ultra-modern way of life coexists peacefully with nature's serene beauty. Almost half - 47 per cent - of the city is marked as national parkland, protecting many geographical heritage sites.
Vigorous volcanic activities shaped Hong Kong's landscape before the age of the dinosaurs. Of the six major types of volcano in the area, the most popular was the ash-cinder volcano, which released lots of magma (melted rock) and ash clouds into the sky.
This explains why we now have many igneous rocks (cooled magma) in our geoparks and other uncultivated lands. Various kinds of rocks - lava rock, volcanic ash tuff, granite and basalt - appeared.
At High Island, some 'younger' rocks formed between 165 million and 140 million years ago. The site boasts the world's largest hexagonal columns, lining up along the coast. They are mainly dark grey and pink and more than 100 metres tall.
Cheung directed our attention to folds, faults and unique geologic features. He described such phenomena as weathering, when rocks alter their colour, texture or composition.