What is longshore drift and what coastal defence mechanism is associated with it? Give examples.

The prevailing wind is the known common direction that the wind blows along a coast, whether that is east, south west etc. it is specific to each specific site. Longshore drift is the movement of sediments along a coast. The direction of the local prevailing winds dictate which direction the sediments will move. Longshore drift causes a zig zag movement of the sediment along the coast as the swash moves the sediments 45 degrees up the coast and the backwash pulls the sediments 90 degrees back towards the sea, see diagram.Groynes are wooden structures that help prevent the movement of sediment along a coast (see diagram); this may be desirable in areas that want to develop more sand along their coasts whether that be for tourism or as a further coastal defence system. The north wales coast shows a distinct longshore drift movement eastwards from Rhos to Rhyl. Groynes are present here.