Shaping the Coast

How coastal landforms are formed by deposition and erosion

Processes of deposition and erosion, with diagrams

For GCSE AQA Geography (A) - Coastal Zone

Exam Monday 13th June

HideShow resource information
  • Created by: Patrick I
  • Created on: 09-06-11 14:08
Preview of Shaping the Coast

First 388 words of the document:

Coastal Zone Shaping the Coastal Zone Geography Revision
Coastal Weathering & Erosion
Rock is broken down through Mechanical and Chemical Weathering
Chemical Weathering: The breakdown of rock by changing its chemical composition.
Carbonation weathering is a type of chemical weathering which happens in warm and wet climates
Rainwater has carbon dioxide in it, which forms a weak carbonic acid
Carbonic acid reacts with rocks which contain calcium carbonate, and the rocks are partially
dissolved by the rainwater
Mechanical Weathering: The breakdown of rock without changing its chemical composition.
Freeze-thaw weathering is the main type of mechanical weathering which affects coasts
In areas where the temperature alternates above and below freezing point, water which
gets into cracks in the rock expands, and puts pressure on the rock
The water thaws and releases the pressure, but the crack may have widened ­ repeating this
process causes the rock to break up
Hydraulic Action: Waves crash against rock and compress the air, putting pressure on the rock.
Repeating this process with every wave widens the crack and causes the rock to break apart
Abrasion: Eroded particles in the water scrape against rock, removing small pieces
Attrition: Eroded particles in the water collide and break into smaller fragments. This rounds the
rocks, and makes them smaller
Corrosion: Weak carbonic acid in seawater dissolves soft rocks such as chalk and limestone
Destructive Waves
The waves which carry out erosional processes are called destructive waves
These have a high frequency (10-14 waves per minute)
They are high and steep
Their backwash (movement of water back down the beach) is more powerful than swash
(movement of water up the beach) ­ meaning material is removed from the coast
Two main factors affect size and power of destructive waves, and how much they erode the
coast as a result:
o Wind: The force of the wind on the water's surface is what creates waves. A strong
wind gives large, powerful waves
o Fetch: The fetch is the distance of water over which the wind has blown to produce a
wave. A greater fetch produces a bigger and more powerful wave

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Coastal Zone Shaping the Coastal Zone Geography Revision
Coastal Landforms Caused by Erosion
Cliff Retreat
Cliff retreat occurs at the foot of a cliff
The processes which cause cliff retreat are hydraulic action and abrasion
Initially, hydraulic action, quickened by corrosion, form cracks at the base of the cliff
These cracks become larger over time, as the waves continue to expand them and abrasion
breaks away more rock.…read more

Page 3

Preview of page 3

Here's a taster:

Coastal Zone Shaping the Coastal Zone Geography Revision
Headland Erosion
Headlands are made from resistant materials, which is why they stick out.…read more

Page 4

Preview of page 4

Here's a taster:

Coastal Zone Shaping the Coastal Zone Geography Revision
Coastal Transportation and Deposition
Transportation ­ The Movement of Material
Material is transported along coasts by the process of longshore drift:
o Waves follow the direction of the prevailing (most common) wind
o These usually hit the coast at an oblique angle (not a right angle)
o The swash carries material up the beach in the same direction as the waves
o The backwash then carries materials down the beach at right angles, back towards
the sea.…read more

Page 5

Preview of page 5

Here's a taster:

Coastal Zone Shaping the Coastal Zone Geography Revision
Coastal Landforms Caused by Deposition
Beaches are found on coasts between the high water and low water mark
They are formed by constructive waves depositing material such as sand and shingle
o Sand beaches are flat and wide ­ as sand particles are small and the weak backwash
is able to move them back down the beach, giving a long, gentle slope
o Shingle beaches are steep and narrow ­ as shingle particles are much larger…read more


No comments have yet been made

Similar Geography resources:

See all Geography resources »See all resources »