Sometimes waves can pick the coast up with them as they roll in and out.
Waves can erode parts of cliffs made of pebbles and sand and spread it along the beach, for example during a high spring tide.
This broken down sediment is there to be rolled, pushed, dissolved and dumped into an ever changing mosaic of mobile landforms that can disappear, and re-appear overnight.
Shingle bars and spits
On the east coast of England shingle bars and spits have formed by coastal processes such as longshore drift.
Sediment is removed by waves and currents from or along the beach, and is deposited offshore when the waves or currents can't carry it any further.
A spit is formed of sand and shingle and is still attached to the coast. A shingle bar may appear at some distance from a beach and can be an offshore island at low tide for a few hours.
Blakeney Point and Scolt Head, Norfolk
© NTPL / Joe Cornish
In Norfolk the shingle has formed a large spit at Blakeney Point and an offshore island at Scolt Head. Over time, and with the right conditions, the offshore island could get higher through a series of cycles as material is deposited and vegetation starts to colonise the shingle and sand.
Orford Ness, Suffolk
© NTPL / Joe Cornish
In Suffolk the shingle has formed over hundreds of years to form the long spit at Orford Ness which is approximately 12 miles long and a mile wide. Here the spit has changed the course of the River Alde so the river reaches the sea many miles to the south.
Loe Pool, Cornwall, and Stackpole, Pembrokeshire
© NTPL / Joe Cornish
Where the sediment supply moving down the coast has managed to block the mouth of a river, freshwater barrier pools form. These pools are generally isolated from salty conditions except at extreme spring tides or during some winter storms when the waves can ‘over top’ the shingle. Loe Pool and Stackpole are examples of barrier pools.
Horsey Mere, Norfolk
| In the east of England freshwater meres like Horsey have formed, often from old flooded peat workings. Brackish lagoons, reedbeds and grazing marsh are often a feature of poorly drained areas like Salthouse Broad and Stiffkey Marshes in Norfolk, and marshes on Orford Ness and at Alnmouth in Northumberland. |
© NTPL / Jonathan Cass
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Sand dunes
Sand dunes can form where there is a great supply of sand that can be built up if the right conditions prevail.
At high spring tides debris like seaweed is left on the strandline of beaches. Seeds of specialist plants can germinate and start to colonise. These small plants form a small obstruction which slows wind down, drops the sand out of the wind stream and deposits it round the plant.
The plants can continue to grow and the dunes eventually become large once marram grass takes hold.
© National Trust
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There are many examples of sand dune systems owned by the National Trust. In Gower at Nicholston and Whiteford Burrows, at Formby in Merseyside, East Head in Hampshire and Woolacombe in Devon. At Portstewart Strand in Co Londonderry, Newton Links in Northumberland, and Pegwell Bay in Kent dunes form large areas on the coast. |
Mud flats
In more sheltered areas of coast and estuaries a sediment supply of mud material can create an extensive area of valuable habitat for a whole range of creatures.
At low tides the inter-tidal mud flats can become exposed and allow access for feeding birds on the animals that live in and on the mud.
Newtown Marshes, Isle of Wight
| At Newtown Marshes on the Isle of Wight there are good examples of inter-tidal mud flats. |
© National Trust
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Salt-marshes
Where the sediment material has collected at the top of the shore and on the edges of creeks, extensive areas of salt-marsh can form where salt and flood tolerant vegetation lives.
© NTPL / Joe Cornish
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Salt-marshes have formed at Brancaster in Norfolk, Llanrhidian Marshes in Gower, Orford Ness in Suffolk, and at Alnmouth in Northumberland, often with intricate tidal creeks. |
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