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Coastal Processes - CurrentsA current is generally taken to be a steady flow of water in a particular direction. There are different types of current, oceanic currents and inshore currents. The oceanic currents are divided into two categories, surface and deep ocean.The deep ocean currents are driven by differences in temperatures of the water. At the poles water cools rapidly and sinks to the bottom of the ocean where it flows towards the Equator. At the Equator it is forced upward to the surface where it is heated by the tropical sun. It then heads away from the equator back to the poles, where the process begins again. These oceanic currents are important in maintaining the global heat balance. The oceanic surface currents are driven by persistent winds. The movement of the air literally pushes the water along and over time a fairly stable current can be formed such as the Gulf Stream. The Gulf Stream carries warm waters from the Gulf of Mexico across the Atlantic to the Western shores of Europe. This current is important in maintaining warmer seas than our locality would otherwise allow. The inshore currents are generally more important to local coastal processes. Local inshore currents can be driven by tidal action and winds and affected by seabed topography and river discharge. They are important in the redistribution of sediments throughout coastal areas. Within the Liverpool Bay area the predominant bottom currents travel from west to east and are important for carrying sandy sediments to the Sefton Coast. Formby Point is a divergence point for some of these currents and as a result there is a net drift of sediment to the north and south along the Sefton Coast.
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