Suction effects on the dilatancy of recompacted CDG 456 9.8 Summary 457 References 458
9.1 GENERAL DESCRIPTIONS OF DECOMPOSED ROCKS IN HONG KONG
Formation and distribution of decomposed rocks
Hong Kong is a mountainous city subject to subtropical climate conditions. Figure 9.1 shows a geological map of Hong Kong that illustrates the distributions of rock types (Irfan, 1996). The predominant rock types in Hong Kong are Mesozoic volcanic rock and granite, which constitute about 85% of rock outcrop on the island (Sewell et al., 2000). The volcanic rocks include tuffs, tuffites, lavas and sedimentary rocks. They occupy about 50% of the surface area of Hong Kong. Intrusive igneous rocks, which comprise mainly granite and granodiorite, account for about 35% of the surface area of Hong Kong. A detailed classification and description of the volcanic and granitic rocks in Hong Kong is given by Sewell et al. (2000).