can create caves, arches and stacks along a headland. Weathering can also help to create these landforms.
- Caves occur when the waves force their way into cracks in the cliff face. The water contains sand and other materials that help to grind away at the rock until the cracks become a cave.
- If the cave is formed in a headland, it may eventually break through forming an arch.
- The arch will gradually become bigger and bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
Spits are created through the process of deposition. A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end.
Spits are commonly formed where there is a prevailing wind and where there is a longshore drift. An example of a spit is Spurn Head, found along the Holderness Coast in Humberside.
The development of a spit is shown below:
Groyne on the East coast of England Groynes in the Waal river, part of the
Rhine in the Netherlands
Groynes in Sitges
The purpose of a groyne is to create and maintain a healthy beach on its updrift side, which in turn provides protection to the land behind. These effects are achieved through two main processes. First, groynes act as a barrier to physically stop sediment transport (sand) in the direction of longshore transport through the system. This causes a build-up of the beach on the groyne's updrift side. Secondly, groynes interrupt the tidal flow forcing the tidal current further offshore beyond the groyne end. This slows the tidal current inshore causing the deposition of heavier sediments and encouraging the beach to grow in size.
Seawall in production in Galveston, TX, USA,
Seawall in Poland
Seawall in Ventnor, UK
A seawall is a form of hard coastal defence constructed on the inland part of a coast to reduce the effects of strong waves and to defend the coast around a town or harbour from erosion. The walls can be sloping, vertical or curved to reflect wave power. The term is typically used to describe walls built on the land parallel to the coast, but may also apply to breakwaters and groynes which are built in the water.
Coastal management or coastal defense is used to throughout the world for many different purposes, but predominantly to reduce coastal erosion and flooding. There are many techniques of coastal management including "hard" and "soft" construction and planning approaches. Hard construction is the more traditional response to erosion and involves the construction of structures which stop wave energy reaching the shore, or absorb and reflect the energy. These have often caused problems themselves, such as increasing erosion elsewhere, and soft construction techniques have become more popular because of this. These techniques involve promoting natural systems such as beaches and salt marshes which protect the coast, and are usually cheaper to construct and maintain than hard construction techniques, and may be self-sustaining.
In some jurisdictions the terms sea defence and coastal protection are used to mean, respectively, defence against flooding and erosion. The term coastal defence is the more traditional term, but coastal management has become more popular as the field has expanded to include techniques that allow erosion to claim land.
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