The set of mechanisms that operate along a coastline, bringing about various combinations of erosion and deposition. A cliffed coastline is affected by slope processes and by wave activity. Both agents give rise to distinctive land-forms, including the geo, the bevelled cliff, and the ‘blow-hole’ (a chamber with a relatively narrow exit at the top of the cliff, from which water and spray are forced when waves are driven against the coast). A low coastline is largely affected by processes in the surf zone, where most work is done by shoaling and breaking waves, and in the offshore zone, where tidal currents are the chief agents of sediment transfer.