- Marine Erosion: Erosion caused by the action of the waves and the sea breaking which removes material.
- Fetch: Distance of the winds blowing across the water.
- Long fetch can create bigger waves coming across the Atlantic
- Storm winds create big waves
- Strong waves combined with high tides create problems like cliff erosion and coastal flooding.
- Waves create more sediment. Waves can also be constructive or destructive.
Types
of Waves #1: Constructive Waves:
- More deposition, occur in summer, flat and gentle waves, sand is carried and forms a berm, a smaller longshore, weak backwash. A Little sediment is carried back to the beach. Wave remains circular.
Types
of Waves #2: Destructive Waves:
- More erosion, occurs in winter, high and steep waves, large material = storm beach, larger longshore, gradient decreases down the beach. Water is directed forwards
Beach
Sediment Profiles.
- August shows a slight berm, September has a steeper backshore.
- Storm beaches are steeper, with boulders at the backshore area.
- Berms are smaller ridges of sand which are closer to the water.
- Beach profiles can change depending on time-courses such as Winter or Summer.
Erosion:
- Erosion is the breakdown and removal of material over time.
- Coastal erosion is mainly caused by waves known as marine erosion.
- Soft geology erodes more easily whereas harder geology is more resistant so erosion is slower.
Types
of Erosion:
- Corrasion (Abrasion): Waves throw rocks into cliffs where they smash and erode. Erodes any cliff that has a shingle.
- Hydraulic Action: Waves pounding cliffs forcing air into cracks with high pressure. Erodes any cliff that has a crack, join or fault. Most common type.
- Corrosion: The rock slowly dissolves. Erodes sediment which is weak. Does not erode igneous rocks.
- Attrition: Scrapes together as it is moved by the waves where they become smaller and rounder.
- Large waves = more erosion, destructive waves erode the most
- Soft geology = more erosion.
Landforms
of Coastal Erosion – Wave-Cut Notch:
- At high tide, destructive waves reach the base of a cliff where they break onto the clip via hydraulic action. Curved wave cut notch forms along the length of a cliff.
Wave-Cut
Platforms:
- Base of the cliff is eroded and the rock above is left unsupported and collapsed. Leaves a flat sloping area where land used to be. Can have rock pools or small ridges.
Cliffs:
- Vertical or near-vertical slopes caused by waves undercutting the land at high tide. Gravity is able to cause mass movement. Movement depends on the type of geology.
Cave-Arch-Stump-Stack
Sequence:
- Cracks open by hydraulic action
- Cracks grow into a cave by hydraulic action and abrasion.
- Cave becomes bigger
- Caves break through the headland forming a natural arch
- Arch erodes and collapses
- Leaves a tall rock stack
- The stack is eroded forming a stump such as the Old Harry Rocks.
- Large wave cut platforms are when erosion pushes the cliff back such as in the Philippians.
- In Cornwall, igneous rocks are eroding slowly by abrasion and hydraulic action.