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How are waterfalls formed?
There’s a horizontal band of more resistant rock positioned over exposed, less resistant rock.
Soft rock is eroded quicker than hard rock (hydraulic action) causing undercutting of the hard rock.
The hard rock overhangs until it can no longer support its own weight and collapses.
Abrasion and hydraulic action vertically erode the soft rock to create a plunge pool.
The process of undercutting and collapse is repeated, resulting in the waterfall’s retreat upstream and the plunge pool getting deeper.
A steep-sided valley known as a gorge is left where the waterfall once was before it retreated.
How are V-shaped valleys and interlocking spurs formed?
The upper course of a river doesn’t have enough energy for suspension of particle and instead transports it using traction or saltation.
This results in vertical erosion of the riverbed.
This creates a V-shaped valley.
If there are areas of hard rock which are harder then the river will bend around them, creating interlocking spurs.
How are meanders formed?
In the middle course, the river gains more water and therefore more energy.
Material can be carried in suspension and this material laterally erodes the river banks, widening the river.
When river flow is stronger on one side, most of the water is pushed to that side, causing increased speed due to less friction.
Lateral erosion via abrasion and hydraulic action on the outside bend causes undercutting of the river bank to form a river cliff.
The inside bend has less water and thus increased friction, so the water slows down, loses energy and deposits material. The build-up of deposited sediment is known as a slip-off slope.
How are oxbow lakes formed?
Due to continued erosion of the outside of a meander and deposition on the inside, the ‘neck’ of land within the meander is narrowed.
Over time, or if there’s a very high discharge (during a flood), the river will cut across the neck to take a new, straighter and shorter route.
Deposition occurs to cut of the original meander, leaving an oxbow lake.
How are floodplains formed?
In a wide, flat valley (interlocking spurs may have been removed by erosion), a river floods
The water which has flowed into the valley is fastest directly next to the river, but the further it travels, the more energy it loses due to friction with the ground and vegetation, so any sediment it was carrying is deposited.
This leaves a layer of sediment over the valley.
After multiple floods, the floodplain is created, which is wide, flat, and very fertile due to the nutrients contained in the deposited sediment.
How are levees formed?
Levees occur in the lower course of a river where there is an increase in volume of water flowing downstream and it floods.
The water which has overflowed loses more energy as it travels further away from the river.
This means that the largest material is deposited first on the sides of the river banks whereas smaller material is carried further.
The larger sediment builds up on the banks of the river over multiple floods
This creates a natural embankment on the bank of the river, meaning that the channel can carry more water.
What is an estuary?
Where the river meets the sea
The river here is tidal
When there is less water, the river deposits silt to form mudflats.
Where is the River Tees?
North England
Source is in the Pennines ~893m asl.
Flows east
Mouth joins the North Sea
Where is the River Parrett?
South west England
Source in hills in Dorset ~179m asl.
Flows through Dorset and Somerset
Mouth meets the Bristol Channel
Factors that have affected the River Tees
Geology: contributed to the formation of the High Force waterfall. Its source is in an area of limestone, which is soluble and has contributed to the formation of a gentle v-shaped valley. Downstream, the geology changes to be more resistant Whin Sill which is far more resistant and the valley becomes more vertical.
Topography: Source in Pennines, upland area, a lot of rainfall as the moorland is easily saturated
Humans: In 1810, Mondal loop cut off to straighten river for ships. Waste from ships narrowed river around Teesside.
Distinctive land area
Landscape
High land with steep relief
Upland
Low-lying land with gentle relief
Lowland
Landscapes formed by glaciers
Glacial
Landscapes shaped by sea erosion and weathering
Coastal
Landscapes shaped by rivers
Fluvial
Uncultivated grassland
Moorland
Northern and Western regions of the UK
Typical location of upland areas
Resistant rocks like slate, granite, and limestone
Rock composition of upland areas
Cool and wet climate with thin soils
Climate of upland areas
Sheep Farming, Quarrying, Tourism
Land Usage of Upland Areas
S and E of the UK
Location of Lowland Areas
Soft Rocks such as Chalk, Clay, Sandstone
Composition of Lowland Areas
Warmer, Drier Climate with Fertile Soil, Grasslands, Deciduous Forests
Climate in Lowland Areas
Quarrying, Tourism, Dairy, Arable Farming, Urban Areas
Land Use in Lowland Areas
Upland Areas in the N and W of England
Location of Glaciated Regions
Where a River Begins
Source
Where a River Meets the Sea or an Outlet
Mouth
Tributaries
Smaller Rivers Joining Larger River
Area of Land Draining into a Common Outlet
Drainage Basin
Boundary between two drainage basins
Watershed
Meeting point of two streams or rivers
Confluence
All streams/rivers in one drainage basin
Network
Power of waves causing rock cracks
Hydraulic action
Pebbles grinding on rock platform
Abrasion
Sea water dissolving rocks
Corrosion/solution
Rocks breaking apart by knocking
Attrition
Rolling of pebbles and material on seabed
Traction
Bouncing of shingle or sand grains on seabed
Saltation
Suspension of small particles in water
Suspension
Minerals dissolved in rock and carried in flow
Solution
Sea loses energy, drops material carried
Deposition
Distance wind blows to create sea waves
Fetch
Flow of water up beach as wave breaks
Swash
Flow of water back to sea after wave breaks
Backwash
Flat, low energy beach; Swash > Backwash
Constructive waves
High energy, breaks downwards; Strong backwash
Destructive waves
Conditions for creating waves
Constructive waves in calm, destructive in stormy
6-9 waves per minute
Frequency of constructive waves
10-14 waves per minute
Frequency of destructive waves
Waves approaching at an angle to the coast due to the prevailing winds. Swash carries material up at an angle. Backwash is perpendicular to the coast (gravity).
Long Shore Drift
Southwesternly winds (blowing northeast).
Prevailing Wind in the UK
Where and why does deposition occur along the coast?
Sheltered bays
Shallow water
Groynes on the beach.
A section of hard rock jutting out into the sea.
Headland
Bay
Areas where the soft rock has eroded away.
How are headlands and bays formed?
Sea attacks a section of coast with alternating bands of soft rock.
This leaves a section of land jutting out into the sea called a headland.
The areas where softer rock has eroded away are called bays.
How is a cave formed?
Caves occur when waves force their way into cracks in the cliff face. Hydraulic action and abrasion are the predominant erosion processes.
How is an arch formed?
If the cave is in a headland, it may eventually erode through to the other side.
How is a stack formed?
The base of the arch becomes wider through erosion until its roof collapses into the sea, leaving a stack.
How is a stump formed?
The stack will be attacked until it is undercut, collapses, and forms a stump.
Subaerial processes
Processes occurring above the waterline
Freeze thaw weathering
Water filling cracks in rock and expanding when it freezes
Salt cracking
Salt crystals accumulating in rock cracks and causing shattering
Biological weathering
Roots growing into cracks, spreading, and breaking rocks
Chemical weathering
Chalk and limestone reacting with acidic water, forming washable substance
Bedding planes
Horizontal cracks in rock
Joints
Vertical cracks in rock
Landslide
Sudden hillside collapse triggered by earthquake or erosion
Rock fall
Sudden rock collapse from cliff or steep slope
Slumping
Gradual hillside collapse due to saturation and soft rock sliding down
What type of rock are slumping cliffs made of?
Young sedimentary rock that is unconsolidated as the sediment is not 'glued' together well
What is a wave cut platform?
A wide gently sloping surface found at the foot of the cliff
How is a wave cut platform formed?
A wave cut notch first forms by erosion with abrasion and hydraulic action. This undercuts the cliff and the cliff overhangs the notch. The fallen rocks create a wave cut platform by attrition which smoothens it
How are meanders formed?
In a straight river, riffles (shallow with deposition) and channel pools (deep with erosion) will form.
This results in areas of slow and fast water movement.
Helicoidal flow
A corkscrew-like flow of water moves material from the outside of one meander bend to the inside of the next one
Slip-off slope
On the inside of a meander bend, where the river flow is slower, material is deposited and there is more friction, resulting in a slip-off slope
What is a floodplain?
A floodplain is a wide, flat area of land on either side of a river and is covered in times of a flood
How does the National Trust Centre impact Studland Bay?
Pros: Big social input to the area, lots of revenue. Cons: Affects the beauty of the area, considered an eyesore. However: Planting trees, color scheme decided on, uses hot oil to prevent cloud formation.
Describe the journey from precipitation to groundwater of a drainage basin
Precipitation - Interception - Surface storage - Infiltration - Soil moisture - Percolation - Groundwater.
What are the three methods of movement in a drainage basin
Surface runoff, transpiration, through flow, groundwater flow, evaporation.
Zone of saturation
The point at which no more water can fill the pores in the rock.
Water table
The top of the zone of saturation.
Features of the Dorset Coast
Old Harry Rocks: Collapsed arch, cave, stack. - Swanage: Discordant bay of limestone and clay, Swanage Bay, Ballard Point, Durlston Head. - Chesil Beach: Spit, The Fleet Lagoon.
What processes lead to the formation of a river?
Formation of a River
What is the term for a U-shaped body of water that forms when a meander is cut off from the main river flow?
Oxbow Lake
Flood management strategies
Hard engineering
Soft engineering
Forecasting and education
Planning and building design
Coastal Erosion
What is the process of land loss along coastlines due to natural forces like waves and currents?
What are long, narrow islands parallel to the mainland that protect the coast from the full force of storm waves?
Barrier Islands
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