Chapter 10 - The Work Of The Sea

Question 1

Describe the term ‘destructive wave’.

Answer 1

Destructive waves cause erosion during stormy weather.

Question 2

What is the ‘fetch’?

Answer 2

The length of sea over which the wind blows the waves.

Question 3

What are prevailing winds?

Answer 3

Winds that blow regularly from one direction.

Question 4

How does the sea erode?

Answer 4

He sea erodes by hydraulic action, attrition and abrasion.

Question 5

What is hydraulic action.

Answer 5

Hydraulic action is erosion carried out by the force of the waves against the coast. Air is in cracks and compressed by incoming waves. As pressure is released, this can cause a mini-explosion which can weaken and shatter the rock.

Question 6

What is abrasion?

Answer 6

Abrasion is when the sea uses its load of rocks and stones to erode the coast.

Question 7

What is attrition?

Answer 7

Attrition is when the seas load is worn down as the pieces smash against each other so that the stones are smoothed and made smaller.

Question 8

How are bays and headlands formed?

Answer 8

Bays and headlands: When the sea erodes a coastline with bands of hard and soft rock. Sea erodes soft rock faster then hard rock by hydraulic action and abrasion. Soft rock forms bays and hard rock forms headlands.

Question 9

Describe the term ‘constructive wave’.

Answer 9

Constructive waves deposit more material then is taken away.

Question 10

What is a bay?

Answer 10

A wide area of the coast where the land curves inward.

Question 11

What is a headland?

Answer 11

A high piece of land that just out into the sea.

Question 12

What is a sea cliff?

Answer 12

A vertical height of rock along the coast.

Question 13

How are sea cliffs formed?

Answer 13

1. The waves erode and undercut the base of the cliff using hydraulic action and abrasion.
2. Wave-cut notch forms at the base, between high and low water marks, which undermines the rock above.
3. Face of the cliff falls down.
4. A wave-cut platform formed as cliff retreats.
   e. g. Cliffs of Moher, Co. Clare

Question 14

How does the sea transport?

Answer 14

Swash and Backwash, Longshore Drift

Question 15

Explain slash and backwash.

Answer 15

Swash: Water running up the beach from an incoming wave. Transports sand and pebbles
Backwash: Water moves back down the beach
Swash stronger then Backwash: Constructive Waves (building beach)
Backwash stronger then Swash: Destructive Waves (removing beach)

Question 16

Explain longshore drift.

Answer 16

Longshore Drift: When waves hit at an angle, transporting material in zigzag

1. Swash runs up beach at and angle and deposits
2. Material is brought back by backwash
3. Swash moves material along beach making sand-spits, sandbars

Question 17

How is longshore drift controlled?

Answer 17

Damage such as blocked harbours and sand less beaches are controlled by groynes, which trap sand as it’s being transported along the beach.

Question 18

Name 5 features of sea deposition.

Answer 18

Beaches, sandspits, sandbars, lagoons, tombolos.

Question 19

Describe a beach.

Answer 19

-Composed of sand and deposited materials
Storm Beach: Bigger stones and rock deposited at the back of the beach above high water during a storm.
Sandy Beach: Between high and low water mark.
Sand Dunes: Formed when sand is blown and is trapped by plants or stones

Question 20

How does the sea help people?

Answer 20

• Tourism => Resorts and shops e.g. Tramore, Waterford
• Ports => Imports and exports, ferry services e.g. Dublin Port
• Fishing => Trawlers are services by ports e.g. Killybegs, Donegal

Question 21

How do people harm the sea?

Answer 21

Pollution: Oil spills and untreated sewage endanger wildlife

Question 22

How does the sea harm people?

Answer 22

• Flooding: Huge waves flood low-lying places e.g. Netherlands
• Erosion: Farmland and houses are worn away by the sea