"Coasts are very complex environments that are constantly being changed by the forces of nature. Waves pound the coastline, sometimes bringing sediments such as sand onto the beach and at other times striking the coast was so much force that they erode its landforms."
Coastal landforms are categorised into two main types:
- Erosional: Formed by powerful actions of waves and other forces that weather and erode rocks.
Write down a definition for both types of coastal landforms
Waves:
Waves are the most important process shaping coastlines as they play a role in both erosion and deposition. The sea's surface is constantly moving; when wind blows across the surface of the sea, energy is transferred from the wind to the water surface. A wave is energy travelling through the water (this explains why the waves are always bigger when it's windy!)
In the open sea, away from land, waves move as ocean swell in a circular motion. As the wave approaches the shallow shoreline it begins to interact with the seabed. The seabed disturbs the circular motion of the waves causing it to rise up and then gravity eventually causes it to break.
Waves are the most important process shaping coastlines as they play a role in both erosion and deposition. The sea's surface is constantly moving; when wind blows across the surface of the sea, energy is transferred from the wind to the water surface. A wave is energy travelling through the water (this explains why the waves are always bigger when it's windy!)
In the open sea, away from land, waves move as ocean swell in a circular motion. As the wave approaches the shallow shoreline it begins to interact with the seabed. The seabed disturbs the circular motion of the waves causing it to rise up and then gravity eventually causes it to break.
Explain why waves are always bigger when it's windy?
Swash and Backwash:
When a wave break it creates turbulence in the water called swash. As the swash water surges up the beach it carries sediment with it. As the wave energy is gradually lost, most of the water soaks into the sand but the remaining water, called backwash, flows back down the beach and into the sea.
Constructive and Destructive Waves:
When a wave break it creates turbulence in the water called swash. As the swash water surges up the beach it carries sediment with it. As the wave energy is gradually lost, most of the water soaks into the sand but the remaining water, called backwash, flows back down the beach and into the sea.
Constructive and Destructive Waves:
- Constructive: Low-energy waves, when these crash onto the beach it has less backwash and most of its sediment is dropped during the swash, adding to the coastline
- Destructive: High-energy waves, much of the energy will return to the sea during the backwash. Destructive waves can continue to pick up sand and sediment in the backwash and return it to the sea, destroy the coastline.
Are these waves constructive, destructive or both?
Explain some possible outcomes if these waves continued to hit the shore.
Explain some possible outcomes if these waves continued to hit the shore.
In Australia, waves are generally constructive during the summer months, and when the weather is more stormy during the winter months, the waves typically become more destructive.
Weathering:
Although waves are the most important agents of erosion, there are other agents that impact on the wearing down of a coast:
Although waves are the most important agents of erosion, there are other agents that impact on the wearing down of a coast:
- Salt-spray weather gradually breaks up the surface of rock because the salt particles expand and contract as they dry out in the sun.
- Plant weathering breaks up rocks, as plants sent tiny roots in gaps within rocks.
- Animal weathering occurs when sea creatures attach themselves to rock. The animals produce chemicals that attack minerals in the rock, breaking it down.
Produce a "Shaping Our Coastline" poster on WORD, explaining each of these processes in your own words (include an image of each):
- Erosional coastline
- Depositional coatline
- Destructive waves
- constructive waves
- Salt-spray weathering
- Plant weathering
- Animal weathering
Complete the interactive activity on page 141 of Pearson