The Hong Kong UNESCO Global Geopark was inaugurated on the 3rd of November, 2009 and is one of 169 UNESCO geoparks around the world.
By definition, a geopark is a UNESCO-designated area containing one or more sites of particular geological importance, intended to conserve the geological heritage and promote public awareness of it, typically through tourism.
The geopark offers a serene, natural contrast to the bustling finance and business city life within Hong Kong. Thus, it is commonly lauded as a ‘Geopark in the City’.
History
The Hong Kong government first came up with the idea of establishing a geopark in 2008. They commissioned a study to investigate and locate regions where a geopark could be feasibly installed.
Eventually, areas within the New Territories and Sai Kung were selected to represent Hong Kong’s first-ever recognized geopark.
The geopark had gone through a few different names prior to the current one. The Hong Kong Geopark was formerly designated the official name of ‘National Geopark of China’ when it was first instituted. In 2011, it changed its name to the Hong Kong Global Geopark of China, becoming accepted to the Global Geoparks Network. Finally, the Hong Kong Geopark was renamed to Hong Kong UNESCO Global Geopark in 2015 with the international formalisation of the ‘UNESCO Global Geopark’ label.
Main Geological Regions
This is a map of the geopark’s current layout. As can be observed, the geopark is impressively large relative to the rest of Hong Kong.
One of the geopark’s major geo attractions includes the Sai Kung Volcanic Rock Region, distributed over a land-and-sea area of approximately 100 km2. The region consists of a wide array of tuff volcanic rocks, a type of rock made of lithified volcanic ash ejected during volcanic eruptions. The rocks display a unique geological formation called prismatic columnar jointing, a regular structure of closely spaced fractures which form evenly spaced columns. The volcanic rock is 140 million years old - making it one of the most historically and geologically significant formations in not just Hong Kong, but across the world.
The rocks are unmatched elsewhere in the world in terms of scale and composition and contain a variety of interesting geological phenomena such as faults, folds, twisted columns and dyke intrusions.
The Sai Kung volcanic rock region is composed of four main geo areas - the High Island, the Ung Kong Island Group, the Ninepin Group, and Sharp Island. The columnar-jointed volcanic tuff is most prominent in High Island - the rock can be seen across the Sai Kung Peninsula in areas such as the High Island Reservoir and Tai Long Wan. These rocks have also led to the development of sea caves and sea arches in the Ung Kong Island Group, as well as cliffs and coastal scenery in the Ninepin Group.
Another geo attraction within the geopark is the Northeast New Territories Sedimentary Rock Region which includes a wide variety of sedimentary rocks from different geologic periods, including almost all of Hong Kong’s sedimentary rock exposures. The total area of this region is approximately 33km2. The region is composed of five main geo areas -Tung Ping Chau, Double Haven, Tolo Channel, Port Island and Bluff Head. The oldest rocks are from the Devonian geologic period, approximately 400 million years BP. (BP is a time scale used in archaeology, relative to the origin of practical radiocarbon dating in the 1950s.) These rocks are mainly sandstone and conglomerate rock, outcropped in Bluff Head. Permian (290 - 260 million years BP) and Early Jurassic (230 - 160 million years BP) rocks can be found along the coastal area of the Tolo Channel. The rock types include marine sandstone and siltstone, as well as mudstone outcrops. An interesting fact about these rocks is that they are generally dark in colour, a means of identifying whether a rock is of marine origin. Along the timeline, an assortment of reddish sandstone, siltstone, conglomerate and breccia can be found in Port Island and Double Haven. The type of rocks reflects the continental climate of aridity and high temperature during the Cretaceous Period (135 - 65 million years BP). Lastly, the region’s youngest rocks can be found in Tung Ping Chau, including mainly Paleogene (56 - 32 million years BP) siltstone and shale rocks. The diverse mixture of rocks is a testament to Hong Kong’s rich geological history and a perfect addition to the geopark.
The Hong Kong UNESCO Geopark has established itself as not only an area of historical significance, but also as a home to a heterogeneous variety of geological structures and unique landforms. Hong Kong Geopark organises many educational activities to spread awareness about geological heritage and promote ideas such as sustainable development - don’t hesitate to try them out!
In light of the latest developments of COVID-19, the visitor centres of the geopark have been temporarily closed - so remember to visit the geopark at a later time if possible.
Writing: Isaac Chow
Editing: Tisya Gupta
Graphics: Alicia Fok
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