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DetailsTai O. Extensive intertidal deposits occur in the sheltered creek at Tai O. They are almost 1 km wide to the southof the town, although the landward side has been bunded and ponds constructed (038 125) and reclamation fillplaced over the central area to construct an extension to the town (042 128). The creek is tidal and mangrovespersist in places, although many have been cleared. To the north of the town (041 132), the deposits are reclaimedfor agriculture and a pattern of fields has been established.Sham Wat Wan. The intertidal deposits of Sham Wat Wan are about 200 m wide. Numerous boulders andcobbles on the surface have been exhumed from the underlying slope deposits by wave action. The deposits arefringed by mangrove, particularly on the southeast side of the bay. Small sand bars have formed near the high tidelevel between the alluvium of the valley and the intertidal sediments.Tung Chung. Intertidal deposits in Tung Chung Bay are up to 400 m wide and form a fringing strip about 2400 mlong. They are characterized by extensive sandy splays and mangrove-lined channels.Chek Lap Kok (prior to development). There was an unusual development of intertidal deposits, an extensive,shallow fan, largely derived from excavations at the kaolin mine and adjacent test embankment (105 186). Thedeposit consisted of fine sand and silt, produced by washing of the kaolinized granite to the east.Yam O Wan. Prior to construction of the North Lantau Expressway, in Yam O Wan, a northeast-trending inlet,grey, silty intertidal mudflats, up to 300 m wide, fringed the seaward end of coastal slope deposits that extendedseawards into the bay.Shui Hau Wan. In this sheltered east-facing bay, very extensive intertidal mudflats, up to about 700 m wide, havedeveloped as a seaward extension of the low-lying, alluviated valley at Shui Hau, Mangrove-lined creeks are afeature of the flats. The deposits are relatively sandy.Tung Wan. A restricted development of intertidal deposits occurs in the southern bay at Tung Wan, south of theCountry Park Management Centre. The area has been modified by development,Yi O, Intertidal mudflats, up to 400 m wide, cover the floor of the shallow bay at Yi O. The deposits consist of agrey, sandy silt, with numerous cobbles on the surface, indicating they they are probably a winnowed slope deposit,being a seaward extension of the low gradient slope deposit from the adjacent valleys.Ngau Tau Wan - Tai Ho Wan. Tai Ho Wan consists of a tidal mud and sand flats, fringed by mangroves. Theclean sandy beach is marked by a sharp break in slope near high water mark.Offshore Superficial DepositsClassification and DistributionThe Hong Kong Geological Survey has previously subdivided the offshore superficial depositsinto the Hang Hau and Chek Lap Kok formations, based on lithological and palaeontologicalevidence from boreholes, and on interpretations of seismic characteristics (Strange & Shaw,1986; Langford etal, 1989; Strange*; al, 1990). The Hang Hau Formation is younger than theChek Lap Kok Formation. A new formation, the Sham Wat Formation, has been recognised onseismic profiles from the district. Stratigraphically, it lies below the Hang Hau Formation and,within the district, above the Chek Lap Kok Formation, It has a diagnostic seismic signature andappears, from limited borehole evidence, to have recognisable sedimentological andpalaeontological characteristics,A distinctive seismic sequence of very limited extent has been recognised above the rocWieadreflector in the Brothers - Ma Wan Channel This sequence is inteipreted as older than the ChekLap Kok Formation and has been designated as pre-Chek Lap Kok Formation deposits, but ithas not been given formational, or member status. In addition, Channel and TransgressiveDeposits118