PACRIM tour of Hong Kong Geopark

group shot of tour participants
  • By Tony Christie, GNS Science

This one day tour of the northern part of Hong Kong’s Geopark was held on Saturday 21 March and led by Rod Sewell and Denise Tang of the Hong Kong Geological Survey.

The Geopark was established in 2009 and is part of the 40 per cent area of Hong Kong designated as protected ‘green areas’. A variety of sedimentary rocks of Late Palaeozoic, Mesozoic and Cenozoic age are exposed in coastal outcrops, including the oldest and the youngest rocks found in Hong Kong.

A large amount of information on the Geopark including papers and the route map was distributed to participants about two weeks in advance of the tour.

Nineteen participants met the tour leaders at the Conrad Hotel at 8 am, and travelled by bus to the New Territories, and then on to the northeast coast and Tolo Harbour where we boarded a boat at the Ma Liu Shui Ferry Pier and cruised down Tolo Channel to the first stop at Lai Chi Chong (number 1 on map). Exposures here are Jurassic volcaniclastic bedded tuffs probably deposited within a lake that was close to a volcanic centre.

Co-leader Rod Sewell providing an introduction to the Jurassic volcaniclastic rocks at Lai Chi Chong.
Co-leader Rod Sewell (in horizontally striped polo shirt) providing an introduction to the Jurassic volcaniclastic rocks at Lai Chi Chong.

The strata exhibit many soft sediment slump structures and a major slump fold, indicating rapid emplacement of a mass flow onto unconsolidated sediments. We boarded the boat again for a cruise around Port Island, with exposures of Cretaceous volcanic rocks and overlying ‘redbed’ sedimentary rocks, and Bluff Head with folded Devonian sedimentary rocks (the oldest rocks in Hong Kong), to dock at the Tap Mun fishing village for a Chinese style seafood lunch (2 on map). We had time for a quick look around the village, most of us spending this time at a beautifully decorated temple featuring an image of the seafarers goddess. Apparently these temples are present in most of the fishing villages so that the locals can offer prayers for safe fishing.

Fold in Jurassic volcaniclastic rocks at Lai Chi Chong.
Fold in Jurassic volcaniclastic rocks at Lai Chi Chong.

Back on the boat and our next stop was the island of Ap Chau (3 on Figure 1) to look at Early to Late Cretaceous reddish sedimentary breccia. Ap Chau is also well known for an arch which makes a profile of the headland said to look like a giant duck drinking from the sea. The location has a spectacularly near view of the large port of Yantian in Mainland China on the opposite side of the channel.

Denise Tang (centre) explaining details of the Early to Late Cretaceous reddish sedimentary breccia on Ap Chau Island.
Co-leader Denise Tang (centre) explaining details of the Early to Late Cretaceous reddish sedimentary breccia on Ap Chau Island.

From Ap Chau we cruised back to port for the bus ride back to Hong Kong. The entrance to one of the tunnels under Hong Kong harbour gave us an introduction to Hong Kong’s traffic congestion, but nevertheless we got back to the hotel at around 5 pm. In addition to interesting geology, great company and discussions, the day demonstrated that there are large areas of mainland Hong Kong with forested hills and no high rise buildings or people. You can get away from it all in Hong Kong. Unfortunately for photography, the weather was murky and foggy, but on the plus side the temperatures were moderate and pleasant.

Many thanks to Rod and Denise for organising and conducting the tour, and to AusIMM for running it with the PACRIM Congress.

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