Coasts: How do characteristic coastal landforms contribute to coastal landscapes EQ2 Flashcards
What are waves caused by?
Friction between wind & water with some energy from the wind being transferred into the water
What 3 factors does wave size/energy depend on?
- strength of wind - stronger wind= more powerful when they break on the shore
- duration - how long wind blows for
- wave fetch - distance of open water the wind blows over (further wave can travel uninterrupted= more powerful it will be when it reaches the shore)
What are the two types of waves?
Destructive & constructive waves
Constructive waves:
- what energy waves are they?
- what type of wave height do they have? (give an example)
- what type of wavelength do they have? (give an example)
- what type of swash do they have? and what does it do?
- what type of backwash do they have?
- How to describe the wave= wave ‘?’
- what type of beach is produced?
- low energy wave
- low, flat wave height (less than 1m)
- long wavelength (up to 100 m)
- strong swash= pushes sediment up beach depositing it as a ridge of sediment (berm) at top of beach
- weak backwash= deposition occurs on beach
- wave ‘spills’
- build up the beach with a gentle beach profile
Destructive waves:
- what energy waves are they?
- what type of wave height do they have? (give an example)
- what type of wavelength do they have? (give an example)
- what type of swash do they have? and what does it do?
- what type of backwash do they have?
- How to describe the wave= wave ‘?’
- what type of beach is produced?
- high energy wave
- large wave height (over 1 m)
- short wavelength (around 20 m)
- weak swash
- strong backwash= erodes beach material and carried it away from beach creating an offshore ridge or bar
- wave ‘plunges’
- beach is limited, with s teeper beach profile
What does beach morphology refer to?
- what things are included in this?
The shape of the beach
- width & slope (beach profile)
- features like berms and ridges
- type of sediment (single, sand, mud) found at different locations on the beach
Beach profiles:
- what does this refer to?
what can different wave conditions do?
- the pattern of distribution of different sized or shaped deposited material
- change the landforms of beaches
What are beaches formed from?
- and what do waves alter on a beach?
loose material
- waves alter morphology (form & shape) of the beach
what else is morphology affected by?
size & shape of beach material
What can the type of wave in an area depend on? (give an example)
- time of year
- coastal management
e.g.
beach profiles steeper in summer= fewer destructive waves (less backwash)
gentler in winter= more constructive waves (more swash)
What are the 4 marine erosion processes?
- Hydraulic action
- Corrosion
- Abrasion
- Attrition
What 3 factors can affect marine erosion?
- wave type (constructive/destructive)
- wave size (fetch & direction)
- lithology
How can wave type & wave size affect erosion?
- affects the seasonal changes in the amount of erosion
- erosion tends to happen more during winter= greater number of destructive waves
- size and type of waves affects amount of hydraulic action and abrasion
How can lithology affect erosion?
- lithology influences rate of erosion
- weaknesses in rocks= erode more quickly
- more resistant rocks= erode more slowly
What is hydraulic action?
the shear force of the waves force air at high pressure into cracks in the cliff, over time this weakens the rock and causes the joint to widen
What is corrosion?
weak acids in seawater dissolve the rock particles
What is Abrasion?
sediment and stones picked up by waves and wear away at cliffs/headland
What is attrition?
as rocks are moved around by the water they knock into each other gradually becoming smaller and rounder
What does a bigger beach mean?
More energy it can absorb before the waves reach the backshore/cliffs causing erosion
What rock types will lead to more erosion?
Sedimentary
What rock types will lead to less reosion?
Igneous & metamorphic
What is the effectiveness of marine erosion processes determined by?
(5 things)
- The type of wave (destructive or constructive)
- The size of wave (linked to energy)
- The tide level
- The shape of the coastline
- The lithology (characteristics of the rock)
How does the type of wave influence marine erosion processes?
Destructive= hurls material at a greater force into cliffs resulting in faster rates of erosion by abrasion
What marine erosion process is most effective? why?
- what rocks are eroded more quickly by abrasion?
Abrasion
- soft sedimentary rock such as chalk and clays
What does erosion create?
Distinctive coastal landforms
Give examples of 4 distinctive coastal landforms
- wave-cut notches
- wave-cut platforms
- cliffs
- cave-arch stack stump sequence
