Tides are regular fluctuations in sea level caused by the gravitational forces of the sun and moon. Tides drive ebb and flood currents which redistribute fine sediments within bays and estuaries. Coastlines of submergence result from partial drowning of the coast by a rise in sea level or sinking of the land. They tend to be deeply embayed with bold relief. Coastlines of emergence , where submarine deposits become exposed, usually have gentle relief and slope gently toward the ocean.
Rapid emergence can produce raised shorelines and marine terraces .
Global sea level has fluctuated substantially in the past and is presently rising slowly. The present rise may be due to the melting of glacier ice and thermal expansion of the oceans caused by global warming. Wind action is capable of moving dry, fine sediments that are not protected by a vegetation cover and is an effective landforming agent in deserts, semiarid regions and along coasts. The removal of loose particles from the ground surface by wind is called deflation . It can produce blowouts, desert pavements and dust storms.