Chapter 10 Coastal Flashcards
(35 cards)
Define contructive waves
Constructive waves deposit more then they take away, this usually happens when the swash is more powerful than the backwash
What are destructive waves?
Destructive waves erode more then they deposit, this usually happens when the backwash is stronger then the swash
What is a fetch?
I fetch is the length of water the wind can run over
What is hydraulic action
Hydraulic action is erosion carried out by the force of waves crashing and pouding against the coast line. Air is trapped in cracks and compressed and when the pressure is released it causes a mini explosion
What is abrasion
Abrasion is when the sea uses its load to wear away at the coast
Attrition
Attrition is when the sea load smashes against eachother to make smaller smoother rocks
How are bays and headlands formed
Bays and headlands are formed when the sea erodes a coastline with bands of soft and hard rock. The soft rock erodes faster and creates a bay
Define faults and joints
Faults and joints are weaknesses in the rock
How are cracks formed
Faults and joints widen into cracks by the power of the waves
How are caves formed
When cracks widen into caves
What are are blowholes and how are they formed
Blowholes are openings in the roof of a cave where sea spray is thrown up through in storms. Faults and joints are weakened to form a hole that reaches the surface
How are arches formed
When two caves join back to back
When does longshore drift occur?
Longshore drift occurs when waves hit the beach at an angle and retreat straight back down
How do people control longshore drift
Groynes, wooden barriers built straight across the beach, they trap sand as its being transported along the beach
e.g South Wexford coast
How does the sea help people?
- tourism: many people enjoy going to the seaside which has led to the development of seaside resorts, holiday homes and local shops
- recreation: used for halting, fishing, swimming and coastal walks
- ports such as Dublin are used to import and export goods and are also ferry services to Britain and France
- fishing industry: large fish catches by trawlers provide food and these trawlers are serviced by ports such as Killybegs
- oil and gas: deposits of oil and gas are under the sea floor
How do people harm the sea
Pollution: untreated sewage is pumped into the sea and oil spills from ships and pipelines pollute the water. These endanger wildlife and sea life
How does the sea harm people
- coastal flooding: huge waves may flood low-lying areas such as the Netherlands
- 1953 a storm surge flooded the Netherlands an 1800 people died and hundreds of thousands displaced
- erosion of the land: cliff collapses are dangerous
- tsunamis
What are sea walls
Concrete walls to help protect land and towns from flooding. There are often curved to throw the sea back at itself
What are the different ways of protecting against coastal erosion/defending the coast?
- sea walls
- gabions
- rock armour
- marram grass
- groynes
What are sea walls?
Concrete walls built to protect lands and towns from flooding and attack from the sea. They are often curved at the top to throw water back at the sea
Gabions
Wire cages filled with rocks to lessen the power of the sea
Rock armour
Massive rocks piled along a beach to protect sand dunes and the coast
Maram grass
Maram grass is grass grown in sandunes by the local council to catch the sand and stop it from going inland
What are the problems, with longshore drift?
- longshore drift carries silt from the mouths of rivers and sand into harbours and estuaries which can block them up
- it removes sand from beaches which can damage tourist industry
