The Early Cretaceous rhyolitic columnar rock formation, known as hexagonal volcanic rock columns, in the Hong Kong UNESCO Global Geopark has been selected as one of the First 100 International Union of Geological Sciences (IUGS) Geological Heritage Sites.

Making the announcement today, the Agriculture, Fisheries & Conservation Department said the hexagonal volcanic rock columns along the coast and on numerous islands in Sai Kung were named the High Island Formation and it has been incorporated in the geopark since 2009.

The formation comprises a great number of columns that are large, well preserved and widely distributed, making it a globally rare and iconic geological wonder.

The selection of the formation as one of the First 100 IUGS Geological Heritage Sites recognises its international importance, the department remarked.

The IUGS Geological Heritage Sites selection aims to recognise those of high international scientific significance around the world to promote their conservation, education and geotourism.

Announced in Zumaia, Spain, the first 100 sites include Shilin Karst in the Mainland, Uluru/Ayers Rock in Australia, the Grand Canyon in the US and Pamukkale Travertines in Turkey.

There were 181 sites in 56 countries nominated for the selection, all of which were evaluated by no less than three international experts.