12 Questions
What determines the size and energy of a wave?
Fetch and strength of the wind
Which type of wind will produce large powerful waves over a long fetch?
South-easterly
What are the characteristics of destructive waves?
Weak swash and backwash
What is the water that flows back towards the sea known as?
Backwash
What does a tall breaker do?
Breaks downwards with great force
How do constructive waves differ from destructive waves?
Destructive waves are high in proportion to their length
What are the characteristics of a constructive wave?
Strong swash and weak backwash
How does freeze-thaw weathering occur in rocks?
Water enters cracks, freezes, expands, and widens cracks
What is the primary impact of plants on rocks in biological weathering?
Roots burrow down, weakening the rock structure until it breaks
How can rainwater contribute to chemical weathering of rocks?
Rainwater acts as a weak acid that dissolves certain types of rock over time
What describes mudflow as a type of mass movement?
Saturated soil sliding down forming a lobe with a stream at the bottom
What happens during rotational slip mass movement?
Saturated soil collects at the head of the slope
Study Notes
Wave Types
- Wave size and energy depend on fetch, wind strength, and duration
- Long fetch (>8000 km) with south-westerly wind produces large, powerful waves
- Short fetch (<200 km) with south-easterly wind produces small waves
- Constructive waves: high in proportion to length, weak swash, strong backwash
- Destructive waves: low in proportion to height, strong swash, weak backwash
- Destructive waves: steep, close together, remove sediment from beach
- Constructive waves: low, far apart, bring sediments to build up beach
Weathering
- Freeze-thaw weathering: water enters rock cracks, freezes, expands, and widens cracks
- Biological weathering: plant roots burrow, weaken rock structure, and break away
- Chemical weathering: rainwater and seawater (weak acid) dissolve rocks like limestone and chalk
Mass Movement
- Mass movement: downhill movement of sediment due to gravity
- Types of mass movement:
- Rockfall: rocks fall off cliff face, forming scree at the bottom
- Mudflow: saturated soil flows down slope, forming a lobe at the bottom
- Landslide: large blocks of rock slide downhill
- Rotational slip: saturated soil slides down a curved slip plane
Learn about the two different types of waves created when wind blows over the sea: constructive waves that deposit materials and increase beach elevation, and destructive waves that erode materials and decrease beach elevation.
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