Beaches are formed by deposition on coasts between the high and low water mark and are formed when constructive waves deposit material like sand and shingle.
Sand beaches are flat and wide, this is because sand particles are small and a weak backwash can move them back down the beach- creating a long and gentle slope.
Shingle beaches are steep and narrow because shingle particles are large and the weak backwash can't move them so they build up and create a steep slope.
Spits and Bars
A spit is formed when a sharp bend occurs in the coastline, like at the mouth of a river, and the longshore drift continues depositing materal past the bend in the sea. Strong winds or waves curve the end of the spit. The sheltered area behind the spit is sheltered from waves so lots of material builds up there allowing plants to grow and forming a mud flat or salt marsh.
A bar is formed when a spit joins two headlands together. The bar cuts off the bay between the headlands from the sea, forming a lagoon behind the bar.
Case Study Revision
Coastal habitat- Essex Salt Marshes (the Thames Estuary)
Problems- the marsh is under threat because farmers have recently reclaimed land from the sea gradually therefore sea walls were constructed to allow grazing of animals, this then starved the marshes.
Importance of salt marshes- an important breeding site for birs it also acts as a feeding ground for waders and ducks and a stop-over area for migratory birds. They are also an important nursery for many fish and a natural coastal defence.
Management- managed retreat is used to manage the salt marshes, this means large areas which were previously protected by defences are allowed to flood naturally by making gaps in existing sea walls. The RSPB has proposed a…