As sand, soil or rock is eroded (worn away) from one place it has to end up somewhere else! When it settles we call this Sediment - which is taken by the action of wind, water, or ice, and/or by the force of gravity to a new place.
You can see this at the coast. Sand is sometimes washed off the beach so a sandy beach becomes stony, and that sand is washed somewhere else. On some beaches it settles just out to sea, to form a sandbank. Coastlines can change quite dramatically over a period of time as this coastal erosion occurs.
The BBC Bitesize website explains this well, but it's in the Key Stage 3 section (but then all Dorothy's readers are pretty smart, right?) but this little diagram explains the process well. I've changed the information so you can understand what happens.
Erosion is usually a very slow process, it happens over hundreds of years, but sudden changes can happen if enough erosion happens underneath the surface!
To find out more, Dorothy and her friends went to visit the village of Dunwich, in Suffolk.
Dunwich - the City Under the SeaThe tiny village of Dunwich is on the Suffolk coast.
Over the centuries Dunwich has been a Roman fort, the capital of a Saxon Kingdom and the base from which St Felix, the first Bishop of Dunwich, converted East Anglia to Christianity. At the time of the Norman Conquest in 1066 it was the most important sea ports on the East Coast, and the tenth largest place in England!!
There is lots more information here about medieval Dunwich, which has nearly all been washed away into the North Sea. A full kilometre (1000m has been washed away - this map from Dunwich museum shows it well - the far right line was the coast in 1300.
(That was 200 years before the Tudors!)
About 1000m is lost every 1000 years, so that's 1 metre every year. Which is actually quite a lot - especially if you are staying 10 metres from the cliff edge!!!
The cliffs are still being eroded by the wind and the waves and Dunwich Heath is now owned by the National Trust to protect as much as possible, although fighting the weather and the tide is rather a difficult task!! All that remains today are the damaged walls of the Medieval Friary. There is a museum at the beach and you can follow an excellent trail available here.
There are many stories about Medieval Dunwich. People say that whilst you are on the beach, you should stop for a moment and listen. The ancient bells of Dunwich Church are said to be heard from beneath the waves.......