Coasts 1

Question 1

What are constructive waves?

Answer 1

Constructive because they deposit sediments on the beach

Question 2

What are destructive waves?

Answer 2

Destructive as they erode coasts and transport rocks and beach material away

Question 3

differences between constructive and destructive

Answer 3

DE SBS GOLF

—->Deposition/Erosion
—->Size: small/large
—->Backwash vs swash: Swash>backwash /
backwash>swash
—->Gradient: low/high
—->Occurrence: gentle slopes/steep slopes
Sheltered coasts/open coasts
—->Length: long/short
—->Frequency: 6-8 min/10-14 min
—->Height: low/high

Question 4

Explain hydraulic action

Answer 4

• —> Waves strike against the surface and trap air
• —> Air is compressed, exerting pressure on joints
• —> Joints weaken and rocks shatter

Question 5

Explain abrasion/corrasion

Answer 5

• —> Sediments carried by waves ( sand and rocks ) are hurled against the coast
• —> Loosened sediments knock and scrape coastal cliffs
• —> Weakens surface and breaks down the coast
• —> Impact is powerful enough to undercut a cliff

Question 6

Explain attrition

Answer 6

• —> rock particles carried by waves (sand, rocks) rub against each other
• —> break down into smaller pieces
• —> become smoother and rounder

Question 7

Explain solution/corrosion

Answer 7

• —> Seawater reacts chemically with water-soluble minerals in coastal rocks and dissolves them
• —> Limestone rocks easily corroded by carbonic acid
• —> Rocks weakened and disintegrate

Question 8

Formation of cliff and shore platforms

Answer 8

• —> Hydraulic action,abrasion
• —> crack
• —> notch
• —> cave
• —> roof collapses to form steep cliff
• —> overhanging cliff
• —> overhanging cliff collapses
• —> materials deposited at foot of cliff
• —> materials thrown at base
• —> cliff retreats inland
• —> shore platform

1. Hydraulic action and abrasion may erode a crack on the rock surface, enlarging the crack to form a notch
2. Notch deepens to form cave
3. Further erosion cause roof of cave to collapse and form a steep cliff
4. Overhanging cliff is formed
5. Cliff collapses and materials deposited at the foot of the cliff
6. Some materials carried by waves and thrown against the base of cliff, causing further erosion
7. Cliff retreats inland and gently sloping platform appears at base where cliff used to be
8. Called the shore platform, which is submerged during high tides

Question 9

Formation of headlands and bays

Answer 9

• —> less resistant & more resistant rocks
• —> less resistant: eroded faster
• —> more resistant: eroded slower
• —> less resistant: bays
• —> more resistant: headlands

Question 10

Formation of caves, arches & stacks

Answer 10

• —> less resistant rocks @headland
• —> eroded more quickly
• —> hydraulic action and abrasion
• —> Waves attack lines of weakness
• —> Waves undercut it
• —> Forms cave
• —> Hollowed cave
• —> Cave develop on each side
• —> Join caves tgt
• —> arch
• —> roof of arch collapse
• —> Stack

Question 11

Formation of spits and tombolos

Answer 11

• —> longshore drift
• —> transport materials in the same direction
• —> materials deposited in the sea
• —> materials accumulate
• —> materials appear above surface of water
• —> Spit
• —> Wave refraction conc on a point
• —> A hook/curve
• —> Spit extends
• —> connects offshore island to mainland
• —> tombolo