2. Describe the processes of marine erosion. Using examples, explain how marine erosion can affect cliff coastlines. 3. Describe the processes of marine erosion and explain how these processes can influence the formation of a wave-cut platform. 4. Explain how waves can transport and deposit Sediment in coastal areas.
Using diagrams, explain formation of spits & coastal salt
marshes. Describe the effects of human activities can have
upon these landforms.
Describe the main features of spit and salt marshes and explain formation. Explain why spits and salt marshes are subject to change and are considered fragile environments. Suggest ways in which they can be protected. With the help of diagrams, describe the features of 3 different types of coastal depositional landform and explain the formation of each.
Spit is an accumulation of sand and shingle that is attached to a
2. Behind the spit are accumulations of silt and mud that are anchored
by vegetation to produce marsh and creek areas.
3. The laterals represent periods of growth of the spit are formed from
beach sediment transported by longshore drift which accumulates
where the coastline changes direction or where drift is held up by a
river mouth or estuary.
4. Accumulations of mud occur in the shelter of the spit and is
colonised by halophytes.
Fragile environments (spits and salt marshes) & ways in which they can be protected.
Spit and salt marshes are subject to change and are considered fragile environments because Spits can change shape due to both growth (laterals) or erosion.
Storms or removal of sediment supplies can have severe impacts such that these features can be considered fragile. Salt marshes are equally responsive if the shelter of the spit is removed or pollution affects the estuarine or river silts and mud.
Development or changes of sea level can also have severe consequences.
Protection can be afforded by trapping sediment (groynes) or guaranteeing continuous sediment supplies. * Case study: Breaching of spit during storm (Chesil Beach) & Dredging (Poole Harbour)
Coastal depositional landform and formation. Coastal depositional landforms: Spits, bars, dunes and salt marshes and beaches
Beaches Beaches are the main feature of deposition found at the coast,
these consist of all the material (sand, shingle etc.) that has built up between
the high and low tide mark. There are number of different sources of beach material
the main source being rivers, where fine muds and gravels are deposited
at the river mouth. Other sources of beach material include longshore drift
(bringing material from elsewhere along the coast); constructive waves
(bringing material up the beach from the sea) and from cliff erosion. As constructive waves build up beaches, they often form ridges in the beach
known as berms. The berm highest up the beach represents the extent
to which the water has reached during high tide.
Bars: These form in the same way as a spit initially but bars are created where a spit grows across a bay, joining two headlands. Behind the bar, a lagoon is created, where water has been trapped and the lagoon may gradually be infilled as a salt marsh develops due to it being a low energy zone, which encourages deposition. Example of a Bar: Slapton Sands - Devon.
TOMBOLOS Tombolos are formed where a spit continues to grow outwards joining land to an offshore island. Example of a Tombolo: - Chesil Beach - which joins the South Dorset coast to the Isle of Portland.
Cliff profiles owe their form to the geology (Lithology and structure), sub-aerial processes and wave energy along a given stretch of coastline. It takes thousands of years for the cliffs profile to form from complex processes, there are many complicated processes taking place on coasts that affect the profile of a cliff.
Wave action causes three erosional processes, abrasion, hydraulic action and corrosion. These processes are most effective when high energy waves, associated with storm conditions strike coast profiles made of less resistant rocks. Concentrated wave action on cliff leads to undercutting. The three types of wave erosion processes play an important part in forming cliff profile.
Changes in sea level affect the formation and continued existence of coral reefs and atolls Coral is sensitive to heat and light it is also sensitive to changes in sea level as reefs cannot survive long periods of sub-aerial exposure. Falls in sea level can lead to the death of coral and to the emergence of the reef above high water forming low lying land such as keys. The islands become colonized by vegetation. To a certain extent reefs can contend with sea level rise leading to the growth of thick reefs (Darwins model). However rapid rise consequent upon global warming may result in inundation and destruction.
Coastal management Explain how human activities have affected the physical environment in a coastal area or coastal areas you have studied. Explain the problems of the sustainable management of a stretch or stretches of coastline you have studied.
Problems of coastal management and evaluate the solution
Groynes are low walls built out into the sea, usually at right angles to the coastline. They help break the power of the incoming waves and slow down the process of longshore drift.
Steel and rock walls. Steel walls are sunk vertically into the beach to stop the sand moving. Rock walls stop waves removing sands and gravel from the beach.
Embankments. These are high walls that are situated where a beach meets the land or cliff. They are usually made of concrete or stone and bounce back storm waves.
Beach slopes are made shallower to keep the sand and shingle stable.
Dumping sand and shingle offshore to reduce the power and height of the incoming waves.
Building a barrier across an estuary of a river to reduce the risk of flooding (for example the Thames Barrier).
Setting up a storm tide early warning system which provides information about extra high tides.
Preventing building on high flood risk areas. This would minimise the loss of life and damage to property.
Human activities affecting coastal environment.
Sustainable management will be defined along the lines of encouraging Improvement of coasts but within the capacity of the supporting physical systems i.e. minimising environmental degeneration.
In coastal terms this can mean the preservation both of the coastal environment and its exploitation. Thus protection schemes that have severe knock on effects are of limited usefulness.
Similarly ado nothing approach may also have repercussions for the long term coastal environment (loss of fishing, tourism landforms etc). These aspects can be illustrated by reference to a particular case study or more disparate examples.