SEDIMENTARY ENVIRONMENTS/Carbonate Shorelines and Shelves 509 prograded many kilometres westwards into the Florida Strait (Figure 3) The windward (eastern) side (not illustrated in Figure 3) has remained as a steep reef-rimmed escarpment for much of this time Unattached rimmed shelves or carbonate banks are known from many parts of the geological record Tertiary examples are best known from the subsurface studies of the foundations of the Bahama Banks, as discussed above and in Figure Mesozoic examples come from the ancient Tethys Ocean and now form extensive Jurassic limestones in the Betic– Alpine–Apennine mountain chains of Europe In particular, the Jurassic limestones of the Apennines of Italy once formed large unattached platforms that were isolated from the margins of the Tethys Ocean Palaeozoic examples come from the Silurian and Devonian inland seas of Canada Here, communities of corals and stromatoporoids helped to build reefrimmed margins to unattached platforms known locally as pinnacle reefs In the subsurface these platforms are encased in shales or evaporites and contain oil and gas reservoirs hosted in the porous and permeable carbonate rocks Attached Carbonate Ramp in an Arid Tropical Environment The southern coast of the Arabian Gulf offshore from the Gulf Coast States (Abu Dhabi, Dubai, and Qatar) is a fine example of a present-day carbonate ramp The shelf slopes gradually from the low-relief desert of the coastal plain through the coastal waters down to a maximum depth of about 100 m over a distance of a couple of hundred kilometres (Figure 9) This gently sloping shelf morphology is the distinctive feature of a carbonate ramp, and there are no major reef systems or rimmed shelf margins The prevailing winds (‘Shamal’) blow onshore from the north-west, which makes this a storm-wave dominated coastline (Figure 9) Owing to the restricted opening to the Indian Ocean through the Strait of Hormuz and the arid climate, salinities are elevated in the Gulf to 40–45% and are even higher in coastal areas, where evaporite minerals are precipitated from these waters The depth of the wave base, the water depth at which wave-generated currents affect the seafloor, has an important control on sediment texture in Figure The south eastern region of the Arabian Gulf, showing bathymetry and the distributions of the main carbonate sediment types (After Bosence DWJ and Wilson RCL (2003) Carbonate depositional systems In: Coe A (ed.) The Sedimentary Record of Sea level Change, pp 209 233 Milton Keynes and Cambridge: The Open University and Cambridge University Press.)