Coastal Landscapes

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Coastal land lies between the sea and the mainland. Strong winds, atmospheric agents, and sea actions such as tides and waves constantly shape the coast. Coastal landscapes lie within the coastline and have various depositional and erosional features. The range of coastal features help distinguish the different coastal landscapes.

Coastal Landscape

Coastal landscapes have an interaction with marine processes that work to produce depositional and erosional landforms and other features. Coastal landscapes also have an association with the following:

  • Energy and sediment input into the coastal zone.
  • Rock structure and nature or materials that make up the coastline.
  • The time taken to develop or interrupt the process of creating coastal features.
  • Climate and weather patterns that may affect the intensity of coastal processes.

Coastal processes are the main factors that drive the build-up or breakdown of these coastal landscapes. Processes such as erosion, deposition, and transportation affect the sediments and materials here. In any case, these processes tend to change the landscapes of these coastal areas, and can have positive or negative effects depending on the type of coastal process that occurs.

Erosional landforms consist of wave cut platforms, caves, arches, stacks, stumps, bays and headlands. On the other hand, depositional landforms include beaches, spits, bars, tombolos, and sand dunes. 

Beaches are found in low coasts and comprise of stones and sand. These stones are found on the internal areas of the landscape while sand is usually found closer to the seas. Materials that waves deposit on river mouth pile to form debris near the coast, creating barriers, borders, shores and banks. The deposition of these materials usually results in the development of different depositional landforms with unique characteristics.

With the onset of climate change and aggressive weather events, coastal landscapes are at risk of increased erosion, which could cause damaging effects to these coastlines. Communities and biodiversity that exist near these shores are threatened by the destructive waves that can cause loss of habitats.

Certain organisms such as algae and corals can also facilitate the development or destruction of coastal landscapes. Coasts can be sandy or rocky, high or low. High, rocky coasts feature steep cliffs excavated at the bottom by waves. The excavation process makes these structures unstable and prone to erosion. Such coastal landscapes feature creeks and bays that promote the development of ports in these areas.

The following are the four major types of coasts in coastal landscapes:

Rias Coasts 

When the sea invades old river valleys, rias coasts are formed. Their heights create capes and peninsulas. Western Corsica, Galicia and southern-central Greece are good examples of rias coasts. The coastal landscape features creeks, deep gulfs and ports. The sea invades glaciers in old valleys to form fjords while many small rocks and islands result in the formation of rock gardens, also known as skjar coasts. These are usually found in Sweden and Finland. 

High Coasts Featuring Cliffs 

High coasts with cliffs feature rocky, vertical slopes on the sea. They include the English Channel, Normandy, Scotland and Ireland coasts. Waves carve deep cracks at the bottom of the walls , creating unique features such as rocks, arches and caves. Deep cracks, however, are prone to erosion and can cause rocky walls to collapse, leading to withdrawal of cliff walls.  

Coastal Cliffs

Sea action and movements, and the earth’s tectonic movements within the crust are responsible for shaping high coasts. Whereas some caves are submerged in the sea, others are found several meters above the sea level. Capo Palinuro, Circeo, Otranto channel, Liguria, Sardinia and Capri sea caves are good examples of such sea caves. 

Low Coasts 

Weak destructive action of the sea allows materials and debris in the river to settle, leading to the formation of low coasts. Weak sea currents distribute the materials along the coast, depositing them on shallow waters in areas covered with promontories and headlands. The deposited materials are moved to form long piles beneath the waters by the action of waves. The piles eventually emerge from beneath the sea, creating beaches and sandbanks. 

The arrow-shaped beaches feature tongues that extend from the headlands. The beaches can stretch further to set bay borders, leading to the creation of lagoons. When the sea is completely separated from the coastal lagoon, it evolves into a coastal lake such as the Varano and Lesina Lakes in Puglia. 

However, when the mainland is connected to the island through sand strips, tombolos such as Orbetello ponds and the Argentario Mountain are formed. Deposits of materials in low coasts result in the formation of beaches. 

Lagoons 

A lagoon is an enclosed area that is several kilometers wide and typical of low, sandy coasts and shallow waters. Canals can connect lagoons to the open sea to allow exchange of wate., as this helps ensure that the the lagoons get cleaned. The canals close over time, leading to the formation of small coastal lakes. Materials in the river eventually fill up the coastal lakes. The Venice lagoon sandwiched between the Piave mouth and the Po delta is the most popular lagoon worldwide

Coastal Lagoon

When depositional landforms such as spits close off bays, these lagoons usually form. Because of the still waters and low energies found in lagoons, deposition is a common coastal process that occurs here.

Coastal Management 

Coastal management is a critical aspect of coastal landscapes, and involves hard and soft engineering. The former involves Groynes, which are built to protect cliffs from erosion. However, these can hinder deposition of materials further down beaches, thus exposing these areas to erosion. Sea walls reflect wave energy while gabions effectively absorb wave energy.  Rock armour, also known as Rip Rap, effectively and affordably absorb and disperse wave energy.

In general, hard engineering, despite their advantages, can sometimes change the landscapes of coastlines, and can damage coastlines if these are not well-managed and properly installed and monitored.

Soft engineering also helps with coastline management without noticeable effects on the environment. It involves beach nourishment, stabilization of cliffs, and management of retreats. In comparison to hard engineering methods, soft engineering is much more environmentally-friendly and affordable.

A Case Study of the Holderness Coastline 

Depletion of the beach areas and high rates of erosion are major threats to the Holderness coast. Biological and physical weathering and the immense energy of sea waves easily erode soft boulder clay cliffs. Within a century, the sea has claimed more than 29 villages. Valuable farmlands have collapsed into the sea, and the lack of enough sediment along the coast is a major issue in these coastlines. An example of a disaster that has occurred due to the weakening effects of erosion is when the Holbeck Hall Hotel drowned in June 1993. 

Holderness Coastline

Various solutions were developed to help mitigate and solve the problems mentioned above. The following are examples of the hard and soft engineering methods that were made in the Holderness Coast:

  • Erection of a seawall
  • Erection of two rock groynes
  • Erection of offshore reefs along the coastline using old tyres
  • Construction of a large rip rap using granite block that easily absorbs wave energy to reduce erosion

Reference 

  1. Bourman, R. P., Murray-Wallace, C. V., & Harvey, N. (2017). Coastal landscapes of South Australia.
  2. Aberg, F. A., Lewis, C., Nautical Archaeology Society, Society for Landscape Studies, & Joint conference of the Nautical Archaeology Society and the Society for Landscape Studies. (2000). The rising tide: Archaeology and coastal landscapes. Oxford: Oxbow Books.
  3. Bellamy, D. (2002). David Bellamy’s coastal landscapes. London: Collins.
  4. Balkwill, R. (2014). Coastal landscapes.
IMAGE SOURCES:
  1. Coastal Landscape – Colin Trainor, Remote coastal landscapes with tropical forest and strand vegetation growing down to the beach, Lore, Lautem, Timor-Leste, CC BY-SA 3.0
  2. Coastal Cliffs – David Stanley from Nanaimo, Canada, Coastal Cliffs (7108089789), CC BY 2.0
  3. Coastal Lagoon – VanniaAliaga, Llanganuco Lagoon, CC BY-SA 4.0
  4. Holderness Coastline – Harkey Lodger, Nahold, marked as public domain, more details on Wikimedia Commons