Coastal Landforms

Question 1

what is the difference between a swash-aligned beach and a drift-aligned beach?

Answer 1

The waves break at different angles.
(On a drift-aligned beach, the waves break at an angle. On a swash, waves break perpendicular)
*link prevailing winds

Question 2

what are beach cusps and how are they formed?

Answer 2

definition: crescent-shaped indentations that form on beaches of sand/shingle

formation:
- appear in the swash zone at high tide line
- begins with straight beach face with small faults & depressions
- water enters depressions and accelerates, which erodes it and more water is attracted
- ridges on beach slow the water down and causes deposition, increasing size of ridge
- when depression grows, waves lose energy before reaching the end
- waves transport material away in backwash

Question 3

what are beach ripples and how are they formed?

Answer 3

• requires wet sand as the ridges would collapse if dry
• waves flow over the wet sand on a beach
• as waves travel over the beach, circular oscillations pick up sand and form ridges

Question 4

how are beaches formed?

Answer 4

• material is eroded from rocks and cliffs (hydraulic action)
• material is transported by waves (suspension)
• material is deposited on beaches due to energy loss

Question 5

what is wave refraction and how does it work?

Answer 5

definition: the change of direction of waves as they move from deep to shallow water

how it works:
- as a wave approaches a beach, the water gets shallower
- there is an increase in friction between waves and sea floor
- this causes a decrease in wave velocity and therefore wave energy
- the wave bends to be parallel with the shore

Question 6

how does wave refraction affect headlands and bays?

Answer 6

in headlands:
- as a wave approaches a headland, the water gets shallower
- the waves become steeper with a greater height and a lower velocity
- they bend towards the headland
- wave energy is concentrated on the headland, so it is eroded
in bays:
- wave energy is dissipated in bays
- waves are slower and smaller
- deposition in a bay

Question 7

What is the process of the erosion of a headland?

Answer 7

1. Crack (hydraulic action)
2. Small cave (hydraulic action + solution)
3. Larger cave
   (hydraulic action + abrasion)
4. Arch
   (hydraulic action, solution, abrasion)
5. Gap
   (biological weathering, rockfall, hydraulic action + abrasion)
6. Stack
   (hydraulic action, abrasion, solution if soft rock)
   (all weathering)
7. Stump
   (abrasion, solution, all weathering)

Question 8

What is a tombolo and how is it formed?

Answer 8

define: when a spit connects the mainland to an island

formation:
it has the formation of a spit, until:
offshore island changes wave conditions to promote deposition between island and mainland