1. Wave action and coastal landforms
PART TWO!

2. Yesterday, we learned about…
Waves  friction
Wave length, height, crest, trough
Wave action: constructive and destructive
Swash and backwash
Longshore drift
Wave refraction

3. Coastline Erosion Four types: 1) Corrosion 2) Corrasion/ Abrasion
3) Attrition
4) Hydraulic action

4. Corrosion (also sometimes called solution)
A type of chemical weathering where material is dissolved by seawater
There are weak acids in the sea which wear rock down (especially some types of rock such as chalk or limestone)

5. Corrasion/ Abrasion Scouring of the rock
Sand and rock particles in waves wear down rock surfaces (usually at the base of a cliff)
Leaves rock very smooth
Like sandpaper

6. Attrition Rock particles in suspension erode each other
Rock hits rock  particles break down
Hitting each other and getting smaller in size

7. Hydraulic Action
When waves hit the base of a cliff, air is compressed into cracks. When the wave retreats the air rushes out of the gap  cliff material breaks away.
Basically, water and air are compressed into rock fractures  water and air in and out of the rock breaks it apart

8. Undercutting (52-53) Rock eroded and removed at the base of a cliff
Creates a very steep, vertical cliff

9. Cliff erosion features
Caves
Bays
Headlands
Tunnels
Arches
Stacks
Wave-cut platforms

10. Caves, Bays, Headlands
CAVES: Indentation in the weakest rock surface of cliff caused by wave refraction and hydraulic action
BAYS: soft rock wears away faster  bay between headlands
HEADLANDS: Hard rock more resistant to erosion
 erodes into jagged shape that juts out from land

13. Erosion of cliffs caves  bays and headlands  caves tunnels  arch  stack  wave-cut platform
Arch: hole in headland caused by wave refraction
Stack: isolated rock pillar after arch caves
Wave-cut platform: undercutting creates a rock debris platform in water

18. Shoreline depositional features
Spits
Tombolos

19. Spit  Long ridge of sand created by longshore drift
Linear accumulation of sediment attached to land at one end.
Spits are typically elongate, narrow features built to several dozen feet by wind and waves.
Where there is an obstruction or the power of the waves is reduced the material is deposited. The sediment which is deposited usually builds up over the years to form a long ridge of material

21. Tombolo
When sand spit grows long enough that it joins an island to the mainland

23. Types of coasts (54)
Ria: lower part of V-shaped valley flooded with water
 A drowned river valley that remains open to the sea
Fjord: Lower part of U0shaped valley flooded with water
Estuary: lower part of a river valley filled with sediment and submerged by the sea depending on the tides; mix of salt and fresh water; funnel shape with gently sloping sides

24. Ria

25. Coastal Protection 1) Sea wall: man-made wall to prevent wave erosion
2) Groynes: artificial barriers built into ocean to stop movement of sand by longshore drift