Features formed by longshore drift are explained and illustrated. The formation of coastal sand dunes is also discussed. Longshore drift carries material along a beach in a zigzag fashion in the direction of the prevailing wind. The swash carries material both up and along the beach while the backwash only carries material down the beach. Longshore drift is the cause of a spit forming at the mouth of a river. Where a spit grows across a bay, a bar is formed. Where water flows in behind this, a lagoon is formed. A bar extending out to an island creates a feature called a tombolo. Onshore winds can also create depositional features. Where sand is blown inland, obstructions cause the sand to build up forming dunes.

First broadcast:
17 October 2007

This clip could be used to create a series of diagrams explaining the formation of various coastal landforms (spit, bar, lagoon, tombolo and sand dunes). A range of places where these features are found are mentioned, so these could be used as case studies. This clip could also be used to play ‘keyword bingo’. The class are told the topic areas featured in the clip, pupils then each come up with keywords likely to be said and put them in a 3 x 3 grid: the first person to get two lines wins.