Shad Ahmad Geography
Topic 1 – Coastal Landscapes and Processes
Coastal Processes
Erosion – The action of waves wearing away rock.
Hydraulic Action – The force of waves crashing against the cliff.
Abrasion – Rocks picked up by waves and thrown against the cliff.
Attrition – Rocks collide together becoming smaller and rounder.
Solution – Chemical action on rocks by sea water causes them to dissolve.
Weathering – The breakdown of rocks at or near the surface of the ground.
Mechanical (Freeze Thaw) – Water enters cracks, freezes and expands – this process repeats.
Chemical (Acid Rain) – Slightly acidic rain falls on rocks e.g. Limestone, a chemical reaction takes
place and rocks weaken.
Biological – Roots of plants and burrowing animals cause rocks to weaken.
Mass Movement – The downslope movement of rocks under the influence of gravity.
Rock Falls – Rocks fall from a weathered cliff or one which has been undercut by waves.
Slumping – Following heavy, prolonged rain, where permeable and impermeable rock meet, rock
slumps and slides in a rotational movement.
Sliding – Similar to slumping but material moves along a flat surface such as a bedding plane.
Transportation – The movement of material within the water by waves.
Traction – Large boulders are rolled along the bed of the ocean.
Saltation – Smaller rocks are bounced along the bed of the ocean.
Suspension – Sand grains are carried within the water in suspension.
Solution – Lime from Limestone is dissolved and carried within the water.
Deposition – When water doesn’t have enough energy to carry material it is dropped.
,Shad Ahmad Geography
Waves
What causes waves to form?
Waves are created by the wind creating friction on the surface of the ocean.
Why are some waves larger than others?
The strength of the wind.
How long the wind has been blowing for.
The distance the wind has been blowing for (fetch).
What happens when the wave reaches the shore?
As the base of the wave is slowed by friction the top of the wave continues until it topples. The
water rushing up the beach is called swash with the water travelling back out to sea because of
gravity is called backwash.
What are the different types of waves?
Destructive waves – These waves are powerful and cause erosion. They are tall and steep, are
closely spaced and occur between 11-15 times per minute. Here the backwash is stronger than the
swash so material is taken away from the shore.
Constructive waves – These waves have less energy and cause deposition. They are low in height
and widely spaced and occur between 6-9 times per minute. Here the swash is stronger than the
backwash so material is added to the shore.
,Shad Ahmad Geography
Geological and erosional landforms
Discordant coast
Bands of rock run at right angles to the coastline.
Concordant coast
Bands of rock run parallel to the coastline.
Headlands and Bays
A discordant coastline is needed with alternating layers of harder (more resistant) and softer (less
resistant) rock. Softer rock erodes at a faster pace and therefore retreats inland forming a bay.
Harder rock erodes at a slower pace and therefore sticks out to sea forming a headland.
Wave cut notch
Waves attack the base of the cliff cutting out a notch. As this continues the cliff becomes undercut
and the unsupported cliff above will collapse.
Wave cut platform
As cliffs retreat they leave a gently sloping rocky area. This is covered at high tide but visible at low
tide.
Caves, arches, stacks and stumps
Lines of weakness increase in size due to erosion and weathering creating a cave. If 2 caves back into
each other in a headland an arch is formed. Gravity causes the roof of the arch to collapse leaving a
stack. Stacks are attacked by erosion and collapse leaving a stump. Stumps are attacked by erosion
and eventually erode below sea level.
, Shad Ahmad Geography
Depositional landforms
How is sediment moved along the coast?
Longshore drift moves sediment along the coastline. A prevailing wind hits the shore at a 45 degree
angle and waves (swash) follow this angle taking sediment with it. Waves then move back out to sea
at a 90 degree angle due to gravity (backwash) taking sediment with it. This process continues in a
zig zag motion moving sediment along the coastline.
Sand Spit
The process of longshore drift transports sediment along the coast until there is a change in direction
of land. Here the sand is deposited leaving a ridge which is the spit. When winds change direction so
too does the shape of the spit, often curving.
Bar
The process of longshore drift transports sediment along the coast until there is a bay or river
mouth. Sand is deposited leaving a ridge (the same as a spit) but this time it cuts off the bay/mouth
trapping fresh water behind it. Tombolo = Spit meets an island out in sea.
Topic 1 – Coastal Landscapes and Processes
Coastal Processes
Erosion – The action of waves wearing away rock.
Hydraulic Action – The force of waves crashing against the cliff.
Abrasion – Rocks picked up by waves and thrown against the cliff.
Attrition – Rocks collide together becoming smaller and rounder.
Solution – Chemical action on rocks by sea water causes them to dissolve.
Weathering – The breakdown of rocks at or near the surface of the ground.
Mechanical (Freeze Thaw) – Water enters cracks, freezes and expands – this process repeats.
Chemical (Acid Rain) – Slightly acidic rain falls on rocks e.g. Limestone, a chemical reaction takes
place and rocks weaken.
Biological – Roots of plants and burrowing animals cause rocks to weaken.
Mass Movement – The downslope movement of rocks under the influence of gravity.
Rock Falls – Rocks fall from a weathered cliff or one which has been undercut by waves.
Slumping – Following heavy, prolonged rain, where permeable and impermeable rock meet, rock
slumps and slides in a rotational movement.
Sliding – Similar to slumping but material moves along a flat surface such as a bedding plane.
Transportation – The movement of material within the water by waves.
Traction – Large boulders are rolled along the bed of the ocean.
Saltation – Smaller rocks are bounced along the bed of the ocean.
Suspension – Sand grains are carried within the water in suspension.
Solution – Lime from Limestone is dissolved and carried within the water.
Deposition – When water doesn’t have enough energy to carry material it is dropped.
,Shad Ahmad Geography
Waves
What causes waves to form?
Waves are created by the wind creating friction on the surface of the ocean.
Why are some waves larger than others?
The strength of the wind.
How long the wind has been blowing for.
The distance the wind has been blowing for (fetch).
What happens when the wave reaches the shore?
As the base of the wave is slowed by friction the top of the wave continues until it topples. The
water rushing up the beach is called swash with the water travelling back out to sea because of
gravity is called backwash.
What are the different types of waves?
Destructive waves – These waves are powerful and cause erosion. They are tall and steep, are
closely spaced and occur between 11-15 times per minute. Here the backwash is stronger than the
swash so material is taken away from the shore.
Constructive waves – These waves have less energy and cause deposition. They are low in height
and widely spaced and occur between 6-9 times per minute. Here the swash is stronger than the
backwash so material is added to the shore.
,Shad Ahmad Geography
Geological and erosional landforms
Discordant coast
Bands of rock run at right angles to the coastline.
Concordant coast
Bands of rock run parallel to the coastline.
Headlands and Bays
A discordant coastline is needed with alternating layers of harder (more resistant) and softer (less
resistant) rock. Softer rock erodes at a faster pace and therefore retreats inland forming a bay.
Harder rock erodes at a slower pace and therefore sticks out to sea forming a headland.
Wave cut notch
Waves attack the base of the cliff cutting out a notch. As this continues the cliff becomes undercut
and the unsupported cliff above will collapse.
Wave cut platform
As cliffs retreat they leave a gently sloping rocky area. This is covered at high tide but visible at low
tide.
Caves, arches, stacks and stumps
Lines of weakness increase in size due to erosion and weathering creating a cave. If 2 caves back into
each other in a headland an arch is formed. Gravity causes the roof of the arch to collapse leaving a
stack. Stacks are attacked by erosion and collapse leaving a stump. Stumps are attacked by erosion
and eventually erode below sea level.
, Shad Ahmad Geography
Depositional landforms
How is sediment moved along the coast?
Longshore drift moves sediment along the coastline. A prevailing wind hits the shore at a 45 degree
angle and waves (swash) follow this angle taking sediment with it. Waves then move back out to sea
at a 90 degree angle due to gravity (backwash) taking sediment with it. This process continues in a
zig zag motion moving sediment along the coastline.
Sand Spit
The process of longshore drift transports sediment along the coast until there is a change in direction
of land. Here the sand is deposited leaving a ridge which is the spit. When winds change direction so
too does the shape of the spit, often curving.
Bar
The process of longshore drift transports sediment along the coast until there is a bay or river
mouth. Sand is deposited leaving a ridge (the same as a spit) but this time it cuts off the bay/mouth
trapping fresh water behind it. Tombolo = Spit meets an island out in sea.
