Coasts Flashcards
(26 cards)
What causes the formation of waves?
Wind blows over the sea, causing friction with the water surface which forms ripples that develop into waves.
The longer the fetch, the more powerful a wave can become.
What happens to waves when they reach the coast?
Waves break on the beach, causing forward movement as the seabed interrupts the circular movement of water, leading to a rise and collapse of the wave crest.
In open sea, there is little horizontal movement of water.
What is fetch?
The distance the wind blows across the water.
Fetch influences wave energy.
What are constructive waves?
Weak, wide waves that are further apart, created in calm weather, with strong swash and weak backwash, helping to build up beaches.
They have a long wavelength and low height.
What are destructive waves?
Strong, narrow waves that are close together, created in storm conditions, with weak swash and strong backwash, leading to beach erosion.
They have short wavelengths and tall heights.
Define swash.
The forward movement of water after a wave breaks.
Define backwash.
The water moving backwards into the sea.
What is mechanical weathering?
The breakdown of rock without changing its chemical composition.
What causes mass movement?
Shifting of rocks down slope when the force of gravity exceeds the supporting force.
This often leads to cliff retreat.
What are the main causes of cliff collapse?
- Different types of weathering
- Weakening or decay of rocks
- Weather factors such as rainfall and temperature changes.
What is the process that occurs during mechanical weathering?
Water freezes and expands in rock cracks, then melts and contracts, repeating this cycle which weakens the rock.
This can result in rockfalls.
True or False: Destructive waves are characterized by a strong swash and weak backwash.
False.
Destructive waves have weak swash and strong backwash.
Fill in the blank: The _____ of waves tends to erode the coast.
Destructive waves
What is chemical weathering?
Breakdown of rock by changing its chemical composition
Involves reactions such as carbonic acids attacking rocks containing calcium carbonate.
What causes rockfall?
Fragments of rock break away from cliff due to weathering
This occurs when rocks become weakened and detach from a cliff face.
Define landslide.
Blocks of rock slide down hill along a slide plane or bedding planes
Landslides can occur due to various factors including saturation of soil.
What is a mudslide?
Saturated soil flows down slope, containing soil, rock, debris, and bedrock
Often triggered by heavy rainfall or other forms of saturation.
Describe slumping.
Saturated soil slumps along a curved surface, known as a curved slip plane
This process typically occurs in areas with steep slopes.
What is biological weathering?
Weakening of rocks by plants, animals, and microbes
Organisms can exacerbate the weathering process through physical and chemical means.
How do animals contribute to biological weathering?
Animals can burrow into cracks of rocks, making cracks bigger and splitting rock
This activity increases the surface area of rocks exposed to weathering.
What role do plant roots play in biological weathering?
Plant roots grow in cracks, and as they grow bigger, they push open cracks causing the rock to break
This mechanical weathering can lead to significant structural changes in rocks.
List the four forms of coastal erosion.
- Hydraulic action
- Abrasion
- Attrition
- Solution
These processes collectively shape coastal landforms.
What is hydraulic action?
Force & power of waves crashing against the shoreline puts pressure on rock, causing it to break away
This process is significant in coastal erosion.
Define abrasion in the context of coastal erosion.
Pebbles & stones carried in water are hurled at cliffs when waves crash, knocking pieces off
This mechanical process can rapidly erode coastal features.
