1.2.1 How do processes work together to create landform features at different scales in river and coastal landscapes in the UK?

What is weathering?

Breakdown of rock in the landscape around the river

Where does weathering happen? [One term answer]

In-situ

What is freeze-thaw weathering?

Water, upon collecting in a crack in a rock, repeatedly freezes and thaws causing the rock to break into smaller ieces

What is exfoliation?

Repeated heating and cooling of the rock causes expansion and contraction, so the outer rock layer breaks into smaller pieces

What is chemical weathering?

Rocks disintegrate and dissolve in slightly acidic rainwater

What is carbonation (a type of chemical weathering)?

Rainwater absorbs CO2 from the air, becoming, becoming acidic, causing alkaline chalk and limestone rocks to slowly dissolve

What is biological weathering?

Rocks are broken apart by the roots of plants

What are the two main types of mass movement in river valleys?

Slumping and soil creep

What is slumping?

When slope is eroded by the river, undercutting the slope

Fill in the gap:

Slumping often occurs when a _, less resistant material overlies a _, more resistant material

Slumping often occurs when a softer, less resistant material overlies a harder, more resistant material

What is soil creep?

Influence of gravity causes weathered material to slowly move down the slope towards the river

What is abrasion?

Rocks carried in river smash into the bank/bed of the river, wearing it down

What is attrition?

Rocks crash together as they move along in the river, knocking bits off each other

What is hydraulic action?

When water is forced into cracks in the banks/bed of the river, forcing them to expand

What is solution?

Where chemicals in the river dissolve minerals in the bank/bed of the river

When does deposition occur?

1. Reduction in river _

2. _ is reduced due to dry weather

3. _ water

4. Increase in size of the _

5. River _

1. Reduction in river gradient

2. Discharge is reduced due to dry weather

3. Shallow water

4. Increase in size of the load

5. River flooding

What is solution (in terms of transportation)?

Dissolved minerals carried in the flow of the water

What is suspension (in terms of transportation)?

Fine particles, clay and silt, float in the river flow and carried long distances

What is saltation?

Rocks bouncing along the river bed

In what velocity rivers is saltation more frequent?

High velocity rivers

What is traction?

Larger gravels, cobbles and boulders roll over smaller rocks on the riverbed

What is alluvium?

Clay, silt, sand and gravel carried by a river

What is erosion?

Wearing away of the bed and banks of the river channel by AB, HA, solution and attrition

What landforms may typically be found in the upper course? [4 landforms]

1. V-shaped valleys

2. Waterfalls

3. Plunge pools

4. Gorges

Describe v-shaped valleys:

Steep sides and a narrow valley floor

How are v-shaped valleys formed?

1. River erodes downwards in a [ ] gradient through [ ] and [ ]

2. Loose material falls slowly down slope ( [ ] )

3. This material is [ ] away by the river

4. [ ] sides created, flow of water also swings [ ]

5. [ ] [ ], this process results in the valley cut into the hillside to form [ ] [ ]

1. River erodes downwards in a steep gradient through HA and AB

2. Loose material falls slowly down slope (slumping)

3. This material is transported away by the river

4. Steep sides created, flow of water also swings laterally

5. Over time, this process results in the valley cut into the hillside to form interlocking spurs

What are interlocking spurs?

Ridges of hard rock that project alternately from opposite sides of a steep, v-shaped valley

Which two types of weathering occur in v-shaped valleys?

Biological and freeze-thaw on the valley sides

How does a waterfall [and gorge] form?

1. River flows over layers of [ ] resistant rock overlying softer, [ ] [ ] rock

2. Softer rock at base of waterfall [ ] more quickly from [ ] and [ ] of the falling water and its load

3. A [ ] and overhang is created

4. Over [ ], the [ ] eventually collapses under its own [ ] into the plunge pool

5. This causes the waterfall to [ ] [ ], upstream

6. The retreat leaves behind a steep sided [ ] bottomed [ ] called a gorge

1. River flows over layers of more resistant rock overlying softer, less resistant rock

2. Softer rock at base of waterfall erodes more quickly from HA and AB of the falling water and its load

3. A notch and overhang is created

4. Over time, the overhang eventually collapses under its own weight into the plunge pool

5. This causes the waterfall to retreat backwards, upstream

6. The retreat leaves behind a steep sided narrow bottomed valley called a gorge

Where are meanders usually found in a river?

In the middle and lower courses

How are meanders [and slip off slopes] formed?

1. Water travels faster on the [ ] bend, [ ] erosion takes place

2. A [ ] [ ] is created on the outside bend as material falls into the river and gets [ ] downstream

3. [ ] continues on inside bends

4. Erosion [ ] away cliffs on the outside bend

5. Deposition creates [ ] [ ] [ ] on the inside bend

1. Water travels faster on the outside bend, lateral erosion takes place

2. A river cliff is created on the outside bend as material falls into the river and gets transported downstream

3. Deposition continues on inside bends

4. Erosion wears away cliffs on the outside bend

5. Deposition creates slip off slopes on the inside bend

What causes a meander to move across the river’s floodplain?

Continued erosion and deposition

What is the thalweg?

Path of fastest water (least resistance)

Why do slip off slopes form?

As a result of deposition on the meander’s inside bend

How is an oxbow lake formed?

1. Over time, erosion [ ] the river so that meanders travel [ ] each other

2. Perhaps in the event of a [ ], the meander [ ] breaks, creating a straight river and bend

3. [ ] occurs outside of the straight channel, old bend is cut off

1. Over time, erosion bends the river so that meanders travel towards each other

2. Perhaps in the event of a flood, the meander neck breaks, creating a straight river and bend

3. Deposition occurs outside of the straight channel, old bend is totally cut off

What are the only landforms formed due to both erosion and deposition combined?

Meanders and oxbow lakes

What are the depositional landforms in a river?

1. Floodplains

2. Levees

3. Estuaries

4. Point bars

What are the erosional landforms in a river?

1. Interlocking spurs

2. Waterfalls

3. Gorges

4. River cliffs

What essentially is a floodplain?

The deposition of finer, lighter alluvium

Why is a floodplain useful?

The silt makes the land fertile

How are levees formed?

1. [ ] deposited on river bank [ ]

2. Levees grow in [ ] over time

1. Sediment deposited on river bank tops

2. Levees grow in height over time

What does the upper course look like?

River starts as many tributaries, narrow and v-shaped

What does the middle course look like?

Tributaries merging to form a rounder and deeper channel, many meanders

What does the lower course look like?

Very wide and very deep channel, levees, lots of deposition

What is an estuary?

Large mudflats and saltmarshes exposed at low tide that build into permanent habitats on the river (the tidal mouth of a river)

What are distributaries?

Finger-like river chanels which branch away from a main river channel

What is a confluence?

Point where two rivers meet

What is a point bar?

A mound of deposited material found in a river bend

Where are point bars commonly found?

On the inside bend of a meandering river

What are bedding planes?

Natural breaks in the strata caused by gaps in time during periods of rock formation

What are joints?

Vertical fractures caused by either onctraction when sediment has dried out, or tectonic movement

What are folds?

Buckles and crumples of rocks pushed together

Why do folds form?

Formed by pressure during tectonic activity

How do headlands and bays form?

1. Waves erode a [ ] coastline by [ ] and [ ]

2. Soft rock is [ ] resistant, so it erodes quickly to form bays

3. Hard rock is more resistant, remaining [ ]

4. Waves become shallower approaching a headland, making waves steeper and more [ ], [ ] erosion

5. Waves [ ] [ ] where the water is deeper into a bay

6. [ ] [ ] creates a coastline with alternating headlands and bays

1. Waves erode a discordant coastline by HA and AB

2. Soft rock is less resistant, so it erodes quickly to form bays

3. Hard rock is more resistant, remaining headlands

4. Waves become shallower approaching a headland, making waves steeper and more destructive, increasing erosion

5. Waves lose energy where the water is deeper into a bay

6. Differential erosion creates a coastline with alternating headlands and bays

What is a wave cut notch?

A dent in the cliff usually at the level of high tide

How does a wave cut platform form?

1. Sea attacks [ ] of cliff between high and low water mark

2. A [ ] [ ] [ ] is formed by HA and AB

3. As the notch increases in size, the cliff becomes [ ] and [ ], leading to the retreat of the cliff [ ]

4. [ ] carries away the eroded material, leaving a wave-cut [ ]

5. Process repeats and cliff continues to [ ]

1. Sea attacks base of cliff between high and low water mark

2. A wave cut notch is formed by HA and AB

3. As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face

4. Backwash carries away the eroded material, leaving a wave-cut platform

5. Process repeats and cliff continues to retreat

Where are rock pools commonly found?

On wave-cut platforms

Why do rock pools form in wave-cut platforms?

Small depressions in the rock fill with seawater at high tide

How do caves/arches/stacks/stumps form?

1. [ ] widened in the headland through HA and AB

2. Waves continue to [ ] away at the crack, opening up to form a [ ]

3. Cave becomes larger and eventually [ ] through the [ ] to form an [ ]

4. [ ] [ ] [ ] continually widens through further erosion

5. Arch [ ] becomes too heavy and [ ] into the sea, leaving a [ ]

6. The stack is [ ] at the [ ] until it collapses to form a [ ]

1. Cracks widened in the headland through HA and AB

2. Waves continue to grind away at the crack, opening up to form a cave

3. Cave becomes larger and eventually breaks through the headland to form an arch

4. Base of arch continually widens through further erosion

5. Arch roof becomes too heavy and collapses into the sea, leaving a stack

6. The stack is undercut at the base until it collapses to form a stump

What is LSD?

Waves approaching at an angle, moving sediment along the beach in a ZIG ZAG pattern

What depositional landforms might involve LSD? [4]

1. Beaches

2. Tombolos

3. Bars

4. Spits

What is a tombolo?

A ridge of sand/shingle formed by deposition that links an island to the mainland

How does a tombolo form?

1. [ ] transports sediment along the coast

2. Wave [ ] creates an area of low energy in the sheltered water behind an island

3. [ ] builds up sand and [ ] until a ridge connects the island to the mainland

1. LSD transports sediment along the coast

2. Wave refraction creates an area of low energy in the sheltered water behind an island

3. Deposition builds up sand and shingle until a ridge connects the island to the mainland

How is a spit formed?

1. LSD transports sediments along the coast

2. Coastline changes [ ] or reaches an [ ], but LSD continues to carry sediment out to sea

3. [ ] occurs as waves lose energy, building up a ridge of sand/shingle [1 ] [2 ] [3 ] [4 ]

4. Spit [ ] [ ] as more sediment is deposited by LSD

5. End of the spit may [ ] due to changes in [ ] or [ ] direction

1. LSD transports sediments along the coast

2. Coastline changes direction or reaches an estuary, but LSD continues to carry sediment out to sea

3. Deposition occurs as waves lose energy, building up a ridge of sand/shingle attached to the mainland

4. Spit extends outwards as more sediment is deposited by LSD

5. End of the spit may hook due to changes in wind or wave direction

What often form behind spits in sheltered water?

Salt marshes

How does a bar form?

1. LSD transports sediment along the coastline

2. Sediment is [1 ] [2 ] [3 ] [4 ] [5 ] [6 ] [7 ] as waves lose energy

3. Continued [ ] extends ridge across the bay

4. Over time, the ridge eventually joins the two [ ], forming a [ ]

1. LSD transports sediment along the coastline

2. Sediment is deposited across the entrance to a bay as waves lose energy

3. Continued deposition extends ridge across the bay

4. Over time, the ridge eventually joins the two headlands, forming a bar

What is the water trapped behind the bar formed called?

A lagoon