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The thickness of the marble is poorly constrained. On the basis of steep dips in the overlying,tightly folded Mai Po Member on The Brothers islands, it could be more than 1000 m thick. Ahigh gravity anomaly centred on the marble (Figure 6; Busby & Langford, 1994) also indicatesthat it is very thick. Frost (1992) estimated the marble as more than 500 m thick in the westernNew Territories, while regionally, across Guangdong Province, it is c.300 m thick..In the Yuen Long area, Frost (1992) divided the formation into two members. The lower LongPing Member is a dark grey marble, commonly with complex internal structure. The upper MaTin Member is a massively bedded, white marble, and probably forms most of the subcrop northof Lantau Island.No fossils have been found in the marble, either north of Lantau Island or in the northwest NewTerritories. Comparison with strata exposed in Shenzhen (Lai & Mui, 1985) suggests an earlyCarboniferous age, and the formation may be the equivalent of the Shidengzi Formation inGuangdong.Bouguer anomalycontour, mgal•Gravity stationYUE SHAN(LANTAU ISLAND)Figure 6 - Bouguer Gravity Anomaly Contour Map of the DistrictDetailsEast Brother island (prior to development). Between 1 and 2 km east of East Brother island, three boreholesintersected marble below thick superficial deposits. Borehole NS3/14460 (17050 22530) encountered white andg^y marble at -53.5 mPD. The top 1.5 m of the core contained small-scale solution features, but it was mainlywhite, with some hght grey streaks and areas of brown oxide staining or discolouration. As granite and28