Coastal Landscapes

Summary

  • Coastal landscapes lie between the sea and the mainland
  • Coasts are divided into four types
  • Rias, high coasts with cliffs, low coasts and lagoons are typical of coastal landscapes
  • Coastal management is an important aspect of coastal landscapes
  • The Holderness coastline has faced various challenges such as increased rate of erosion over the years
  • Various solutions such as the erection of rock groynes have been developed to overcome challenges at the Holderness coastline

Coastal land lies between the sea and the mainland. Strong winds, agents in the atmosphere and sea actions such as tides and waves constantly shape the coast. Coastal landscape lies within the coastline and has various depositional and erosional coastal features. Coastline forms vary with prevailing features distinguishing one from another.

Coastal Landscape

Coastal landscape involves an interaction between the marine processes working to produce depositional and erosional features. It is also an association between:

  • Energy and sediment input into the coastal zone.
  • Rock structure and nature or materials making up the coastline.
  • The time taken to develop or interrupt the process of creating coastal features.
  • The climate element affecting weathering intensity and range.

Certain organisms such as algae and corals can 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 oceanic waves. The excavation process can cause higher walls to collapse and thus coastal withdrawal. Such coastal landscape feature creeks and bays responsible for the development of ports.

Beaches are found in low coasts and comprise of stones and sand; the former are found on the internal areas of the landscape while the latter becomes finer sea-ward. Materials that waves deposit on river mouth pile to form debris near the coast, creating barriers, borders, shores and banks.

Coastal landscapes feature four major types of coasts as follows:

1. 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 garden or skjar coasts. They are found in Sweden and Finland.

2. 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 the wall bottoms, creating cracks that develop unique features such as rocks, arches and caves. Deep cracks 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 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.

3. 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. The deposited materials are moved to form long piles beneath the waters by sea waves. The piles eventually emerge from beneath the sea, creating beaches and sandbanks.

The arrow-shaped beaches feature tongues with promontories extension. The beaches can stretch further to set bay borders, leading to 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.

4. Lagoons

A lagoon is a stretch of the sea. It 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 water. It also ensures 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 worldwide.

Coastal Lagoon

Coastal landscapes are also typical of landforms and processes. Erosional landforms comprise of wave cut platforms and caves; arches, caves, stacks and stumps; and bays and headlands. On the other hand, coastal processes involve erosional and transportation processes, waves and longshore drift.

Coastal Management

Coastal management is also a critical aspect of coastal landscapes. It involves hard and soft engineering. The former involves Groynes built to protect cliffs from erosion. However, it can lead to beach materials not being deposited further down the beach, exposing the 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. However, the large rocks are not aesthetically appealing. Soft engineering also helps with coastline management without noticeable effects on the environment. It involves beach nourishment, stabilization of cliffs, and management of retreats. As a pro, soft engineering is environmentally friendly and affordable.

A Case Study of the Holderness Coastline

Depletion of the beach areas and high rates of erosion are major threats at the Holderness coast. Biological and physical weathering and the power of sea waves easily erode soft boulder clay cliffs. Within a century, the sea has claimed more than 29 villages. Valuable farmland collapsed into the sea, lack of enough sediment along the coast are major issues at the coastline. Moreover, the Holbeck Hall Hotel drowned into the sea in June 1993.

Holderness Coastline

Various solutions were developed to solve the problems mentioned above as follows:

  • Erection of a seawall to protection a gas station
  • 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