GCSE lesson

14. Beaches develop when the supply of sediment exceeds any sediment lost through backwash and longshore drift. Beaches are usually distinguished as either … Shingle or Sand Shingle beaches are free draining so there is little backwash of material to sea. As a consequence, they are usually steeper.

15. Some features of a shingle beach .. ... The largest material is found furthest from the sea Successively lower berms You get ridges across the beach called berms

16. Sand beaches have a more gentle profile. This is because.... Wet sand compacts, so water doesn’t drain through it. This means that backwash, and the material it is carrying, is able to return to the sea. Sand is smoother than shingle.... so there is less friction to prevent the materials moving back down the beach

17. These get colonised by grasses and become ecosystems As on-shore winds blow across dry beach sand, it carries material inland to form sand dunes

18. Spits and Bars Where there is a change in the coastline e.g. a headland or an estuary mouth, longshore drift may continue to deposit sediments into the sea forming a spit.

19. Spurn Head at the mouth of the Humber estuary is a fine example of a spit.

20. Local currents and changes in wind direction may curve the end of the spit landwards creating a hooked tip. The presence of the estuary discharging river water into the sea prevents the spit from developing into a bar. Such a feature is known as a recurved spit wind

21. If a spit joins on to one part of the mainland to another it is called a bar .

22. For example, there is a bar at Slapton Sands in Devon.

23. Tombolo Where a spit joins the mainland to an island a tombolo may be created . The longest and best known tombolo in Britain is Chesil Beach .

24. Chesil Beach viewed from the Isle of Portland