3.7 – Landforms and Landscapes of coastal deposition
Beaches form when constructive waves deposit sediment on the shore – they are a temporary store
Deposition – occurs when waves no longer have enough energy to transport sediment
Beach accretion: coastal sediment being deposited on a beach making it wider
1. Swash aligned beaches:
- Waves arrive parallel to the shore
- Tend to form in low-energy environments (bays)
- Sediment moves up and down beach with little lateral transfer
2. Drift aligned beaches:
- Waves approach coast at an angle
- Sediment transferred along the coast by longshore drift
Beach forms
Berms – a ridge or plateau on the beach formed by the deposition of sediment by wave action
Cusps – crescent shaped beach formations with graded sediment (coarse sediment collects at the
‘horns’ and finer sediment collects in the ‘bay’ area)
Runnels – the dips in the foreshore area of a beach between ridges (they are drained down the
beach by channels that break the ridges)
Beach profiles
Beach profiles are steeper in summer – waves are
more constructive
Beach profile less steep in winter - destructive
waves occur so strong backwash transports
sediment offshore
Landforms
Spits
a long, narrow feature, made of sand or
shingle, that extends from the land into
the sea (or part way across and estuary)
form on drift aligned beaches when sand
or shingle is moved along the coast by
longshore drift
if coastline suddenly changes direction
(e.g. because of river estuary) sediment builds up – spit
the end of a spit will begin to curve round as wave refraction carries material to more sheltered
water – this is known as a recurved tip
the area behind the spit is sheltered so often develops mudflats and saltmarshes
Tombolo
a ridge of beach material that has formed between and
island and the mainland
deposition occurs where the wind lose their energy and tombolo
begins to build up
Beaches form when constructive waves deposit sediment on the shore – they are a temporary store
Deposition – occurs when waves no longer have enough energy to transport sediment
Beach accretion: coastal sediment being deposited on a beach making it wider
1. Swash aligned beaches:
- Waves arrive parallel to the shore
- Tend to form in low-energy environments (bays)
- Sediment moves up and down beach with little lateral transfer
2. Drift aligned beaches:
- Waves approach coast at an angle
- Sediment transferred along the coast by longshore drift
Beach forms
Berms – a ridge or plateau on the beach formed by the deposition of sediment by wave action
Cusps – crescent shaped beach formations with graded sediment (coarse sediment collects at the
‘horns’ and finer sediment collects in the ‘bay’ area)
Runnels – the dips in the foreshore area of a beach between ridges (they are drained down the
beach by channels that break the ridges)
Beach profiles
Beach profiles are steeper in summer – waves are
more constructive
Beach profile less steep in winter - destructive
waves occur so strong backwash transports
sediment offshore
Landforms
Spits
a long, narrow feature, made of sand or
shingle, that extends from the land into
the sea (or part way across and estuary)
form on drift aligned beaches when sand
or shingle is moved along the coast by
longshore drift
if coastline suddenly changes direction
(e.g. because of river estuary) sediment builds up – spit
the end of a spit will begin to curve round as wave refraction carries material to more sheltered
water – this is known as a recurved tip
the area behind the spit is sheltered so often develops mudflats and saltmarshes
Tombolo
a ridge of beach material that has formed between and
island and the mainland
deposition occurs where the wind lose their energy and tombolo
begins to build up
