The Environment 1 295
of rare plants or animals, through exercising strict development controls. In all, 65 sites have been listed.
The Fisheries Protection Ordinance provides for the regulation of fishing practices and the prevention of destructive fishing activities such as using explosive or toxic substances for the purpose of fishing.
Protected Areas
There are 23 country parks and 17 special areas (six of which are located outside country parks) with a total area of 41 644 hectares (about 38 per cent of the total land area of Hong Kong). They cover scenic hills, woodlands, reservoirs, islands, indented coastlines, marshes and uplands. All are carefully protected for the purposes of nature conservation, education and scientific studies. Management measures include protection of woodland and vegetation against fire, control of development, tree planting, litter collection, the provision of educational and recreational facilities, and the promotion of a better understanding of the countryside.
There are four marine parks and one marine reserve covering 2 430 hectares of scenic coastal areas, seascapes and important biological habitats. Marine reserves are dedicated to conservation, education and scientific studies. Fishing in marine parks is controlled through a permit system confined to local villagers and bona fide fishermen, while such activity is totally banned in marine reserves. Publicity and educational activities are organised for students and members of the public.
Topography and Geology
Hong Kong's natural terrain is characterised by rugged uplands flanked by steep slopes. The highest point is Tai Mo Shan (957 metres above Principal Datum) in the central New Territories, and the lowest point (66 metres below Principal Datum) is in Lo Chau Mun (the Beaufort Channel) to the north of Po Toi Island. The mountains are predominantly formed of volcanic rocks, whereas the lower hills are mainly formed of granite. Low-lying areas are generally underlain by granite or sedimentary rocks. A layer of soft, weathered rock covers the bedrock in most places, slope debris mantles the natural hillsides, and alluvium fills many of the valleys. Offshore, the seabed is covered with marine mud, with sand sheets occurring near the coast and in channels.
The oldest exposed rocks in Hong Kong are composed of Devonian river sediments that were deposited approximately 400 million years ago. The region was subsequently inundated by a shallow sea, in which were deposited Carboniferous limestones, the parent material of the Yuen Long and Ma On Shan marble. Between 170 to 140 million years ago, during the Jurassic and Cretaceous periods, Hong Kong was the scene of violent volcanic activity that deposited thick accumulations of ash and lava. These eruptions were associated with the development of several calderas (giant craters). At deeper levels, molten magma was intruded and slowly crystallised to form granite. Igneous activity ceased 60 million years ago. Layered rocks now seen on the island of Ping Chau are younger sediments, laid down in a lake on the edge of a desert.