coasts csec geography
DESCRIPTION
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RM ACCOUNTS ED
Geography notes
CSEC
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Coasts
Waves rm accounts ed ram@2013
Wave Formation
Frictional force between the wind and the
sea surface
Transfers circular motion to the water
In open water we get swells
As swells approach the shore waves are
formed
Waves break when the depth of the
water is less than the wave height
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rm accounts ed ram@2013
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Type of waves
Two types
Constructive – These build beaches by depositing sand, shingles and pebbles
Destructive – These remove material from the shore
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Destructive Waves These plunge against the shore
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Characteristics - destructive
Backwash is greater than the swash
Backwash > Swash
> 9 per minute
Short wave lengths
Plunge against the shore
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Constructive Waves
These spill onto the shore
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Characteristics - constructive
Swash is greater than the Backwash
Swash > Backwash
< 9 waves per minute
long wave lengths
Spill onto the shore
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Coasts Wave Processes
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Wave Processes
Erode
Transport
Deposit
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Wave Erosion Hydraulic Action – force of the water
alone
Attrition – Load knock against each other
Abrasion or Corrasion – Load erodes the shore
Solution – Sea water disolves minerals in the rock
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rm accounts ed ram@2013
Wave Transportation
The movement of material can be either
of three ways: in, out and along
In, deposition of material to form beaches
Out, removal of material from the shore out
to sea by the undertow
Along the shore is called longshore drift
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Longshore Drift
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The effect of Groynes /
Groines along a beach
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Wave Deposition
Deposition is the laying down of
transported material
Constructive waves and gently sloping
shorelines are associated with deposition
Where rivers discharge into the sea
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Coasts
Coastal Features
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Types of Coastal features
Erosional – those produced by erosion
Examples: cliff, notch, wave-cut platform, headland and bay, caves, arches, stacks and blowholes
Depositional – those produced by deposition
Examples: beaches, spit, tombolo and bars
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Cliff, Notch and Wave-cut
Platform
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Headland and Bay
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deposition
erosion
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Headland and Bay cont’d
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What happens next?
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Wave Refraction
The change in the direction of the waves as they approach the shore, converging on headlands and diverging as they approach the bay
Stronger on the headlands
Weaker in the bay
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Depositional Features
What are the two main conditions which
lead to the formation of depositional
features?
Constructive waves and gently sloping
shorelines are associated with deposition
Where rivers discharge into the sea
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rm accounts ed ram@2013
A Beach
A beach is a depositional feature. What
material is laid down to form a beach?
What is a bay-head beach?
Draw a diagram to illustrate a beach.
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Other Depositional features
Spit
Bar
Tombolo
Draw well labelled diagrams of the
features identified above.
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Borrowed from: http://imgcdn.geocaching.com/cache/large/23a79aff-4609-43ed-a383-011910ee6680.jpg
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A Spit
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A Tombolo
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A Bar – Baymouth Bar
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Borrowed from: greenfieldgeography.wikispaces.com -
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A Bar – Offshore Bar
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thanks
Physical Geography in Diagrams
– R B Bunnett
Dale Franklin – for the teaching concepts
and the initial powe-rpoint.
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