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UNIT 1C - COASTAL PROCESSES (Waves (There are two different types of wave …
UNIT 1C - COASTAL PROCESSES
Waves
When the wind blows over the sea, it creates waves. The size and energy of the wave depends on certain factors:
the fetch - how far the wave has travelled
the strength of the wind
how long the wind has been blowing for
There are two different types of wave - constructive and destructive. They can affect the coastline in different ways. When a wave reaches the shore, the water that rushes up the beach is known as the swash. The water that flows back towards the sea is known as the backwash. The energy of the swash and backwash determine the type of wave.
Destructive waves
weak swash and strong backwash
the strong backwash removes sediment from the beach
the waves are steep and close together
Constructive waves
strong swash and weak backwash
the strong swash brings sediments to build up the beach
the backwash is not strong enough to remove the sediment
the waves are low and further apart
Biological weathering - Plants and animals can also have an effect on rocks. Roots burrow down, weakening the structure of the rock until it breaks away.
Plant roots can get into small cracks in the rock.
As the roots grow, the cracks become larger.
This causes small pieces of rock to break away.
Weathering - Exposed rocks along the coastline can be broken down by the processes of weathering.
Mechanical weathering - is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land. The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart
Chemical Weathering - the erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes.
Freeze-thaw weathering - Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable (allow water to pass through).
Water enters cracks in the rock.
When temperatures drop, the water freezes and expands causing the crack to widen.
The ice melts and water makes its way deeper into the cracks.
The process repeats itself until the rock splits entirely.
Mass movement - Another way material can be moved on the coastline is through mass movement. Mass movement is the downhill movement of sediment that moves because of gravity. There are four different types of mass movement:
