Beaches
- Form when constructive waves deposit sediment on the shore.
- Shingle beachesare steep and narrow; have large particles.
- Sand beachesare wide and flat; have small particles.
- Berms- ridges of sand and pebbles found at high tide marks.
- Runnels- grooves in the sand running parallel to the shore, formed by backwash draining to the sea.
- Cusps- crescent-shaped indentations that form on beaches of mixed sand and shingle.
Spits
- Longshore drift- deposits material across the river mouth, leaving a bank of sand and shingle sticking out into the sea.
- Simple spit- straight spit that grows out parallel to the coast.
- Occasional changes to the dominant wind and wave direction may lead to a spit having a curved end.
- Compound spit- a spit with multiple recurved ends.
- The area behind the spit is sheltered and so develops into mudflats and saltmarshes.
Offshore Bars and Tombolos
- Bars- formed when a spit joins two headlands together. This can occur across a bay or across a river mouth.
- A lagoonforms behind the bar.
- Bars can a form off the coast when material moves towards the coast. These may remain partly submerged by the sea – offshore bars.
- A bar that connects the shore to an island is a
Barrier Islands
- Long, narrow islands of sand that run parallel to the shore ad are detached from it.
- Form in areas with a good supply of sediment, a gentle slope offshore, powerful waves and a small tidal range.
- Formation: ice melt caused rapid sea level rise; flooding the land behind beaches; transported sand offshore; deposited in shallow water.
- A lagoon or marsh forms behind the barrier island, where the coast is sheltered.
Sand Dunes
- Formed when sand deposited by longshore drift is moved up the beach by the wind.
- Sand trapped by driftwood or berms is colonised by plants and grasses. The vegetation stabilises the sand and encourages more sand to accumulate there, forming embryo dunes.
- Over time, the oldest dunes migrate inland as newer embryo dunes are formed.
- Mature dunes can reach 10m in height.
Estuarine Mudflats and Saltmarshes
- Mudflatsand saltmarshes form in sheltered, low-energy environments.
- As silt and mud are deposited by the river or the tide, mudflats develop.
- Mudflats are colonised by vegetation that can survive the high salt levels and long periods of submergence by the tide.
- Plants trap more mud and silt, and gradually they build upwards to create an area of saltmarsh that remains exposed for longer and longer between tides.
- Erosion by tidal currents or streams forms channels in the surface of mudflats and saltmarshes. These may be permanently flooded or dry at low tide.