Fluvial Landforms

• Fluvial landforms


  Landforms created by river processes
• Formation of waterfalls


  1. Hard rock overlies soft rock

  2. Hydraulic action and abrasion erode soft rock faster

  3. Undercutting creates overhang of hard rock

  4. Overhang collapses into plunge pool

  5. Abrasion deepens plunge pool
• Formation of v-shaped valleys

  1. Vertical erosion dominates in upper course

  2. Weathering and mass movement cause valley sides to collapse
• Interlocking spurs


  • Form in upper course where river channel starts to meander
  • Erosion on outside of bends creates interlocking spurs
• Landforms shown in Figure 1

  • Waterfall
  • Gorge
• Layers of soft and hard rock


  Soft rock erodes more easily than hard rock
• Hard rock breaking off and falling

  Increases abrasion and deepens plunge pool
• Erosion on outside of river bends

  Forms interlocking spurs
• Erosion


  Need to give the type of erosion and where it occurs
• This is a levelled answer, so marks are awarded for the answer overall rather than for individual points
• In a level 2 and 3 answer you are expected to use geographical terms and include examples of at least two landforms - waterfall and gorge
• An example of an answer for each level can be seen below
• These are just examples and there are many others which can be found in the mark scheme - see topic question 10
• Formation of a waterfall

  1. Soft rock erodes more easily than hard rock

  2. Hard rock falls into the plunge pool at the bottom

  3. Process is repeated and the waterfall moves backwards
• Formation of a waterfall (level 2)

  1. Soft rock erodes more quickly than hard rock leaving the hard rock unsupported

  2. Hard rock breaks off and falls to the bottom of the waterfall into the plunge pool leading to more erosion

  3. This process repeats over and over again causing the waterfall to retreat upstream
• Formation of a waterfall (level 3)

  1. River flows over hard rock with soft rock underneath

  2. Softer rock is eroded more rapidly than the harder rock by hydraulic action and abrasion leading to undercutting of the hard rock and the formation of a plunge pool

  3. Hard rock is no longer supported and breaks off falling into the plunge pool which then increases abrasion and further deepens the pool

  4. This process is repeated causing the waterfall to gradually retreat upstream leaving behind a steep sided gorge
• Landforms created through a combination of erosion and deposition


  • Meanders
  • Ox-bow lakes
• Formation of meanders


  1. Lateral erosion is dominant in lowland areas

  2. Meanders increase in size

  3. Fastest water flow (thalweg) is on the outside of the river bends, leading to erosion

  4. Slowest flow is on the inside of the river bends, leading to deposition

  5. Deposition on one side and erosion on the other leads to the meander migrating across the valley
• Formation of oxbow lakes

  1. With distance downstream the size of the meanders increase

  2. Erosion on outside bends can eventually lead to the formation of a meander neck

  3. At a time of the flood, the river may cut through the neck of the meander forming a straighter course for the water

  4. Flow of water at entry and exit from the meander will be slower, leading to deposition

  5. Meander becomes cut off from the main river channel, forming an oxbow lake
• Remember when describing the formation of oxbow lakes it is important to state that the river will break through the neck of the meander during a flood. At other times the river does not have enough power to break through.
• Formation of floodplains and levees

  1. Migration of meanders leads to the formation of the floodplain

  2. High discharge may cause the river to overflow the banks

  3. More of the water is in contact with the land surface as the water spreads across the floodplain

  4. Increased friction reduces velocity and material is deposited across the floodplain gradually increasing the floodplain height

  5. Heaviest material is deposited first nearest to the river channel forming natural embankments called levees
• Formation of estuaries


  1. Large deposits of sediment form mudflats and salt marshes

  2. Incoming tides bring in sediment which mixes with the sediment being carried by the river

  3. When the incoming tide of salt water meets the freshwater of the river, the river velocity drops and deposition occurs

  4. Deposited sediment builds up in layers to form mudflats which rise above the water surface, particularly at low tide

  5. Vegetation starts to grow on the mudflats and form salt marshes
• Formation of river levees

  1. Levees are long narrow ridges or raised embankments alongside the river

  2. Composed of gravel, stones and alluvium/ Steeper on channel side than land side

  3. Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs

  4. Sediment that has been eroded further upstream is transported downstream

  5. When the river floods, the sediment spreads out across the floodplain. Friction with the land reduces velocity and causes deposition

  6. Largest material (sand and gravel) is deposited first on the sides of the river banks and smaller material (finer silt and mud) further away

  7. After many floods, the sediment builds up to increase the height of the river banks, so the levées become higher than the surrounding floodplain

  8. If a severe flood event occurs, levées may burst and cause serious damage to surrounding land
• The River Tees is located in north-east England
• It is 85 miles from source to mouth
• It flows eastwards from the source in the Pennines to the mouth where it flows into the North Sea
• Formation of High Force waterfall

  1. Hard igneous rock (dolerite) lays over a softer sedimentary rock (limestone)

  2. Water erodes the limestone more rapidly, undercutting the hard dolerite

  3. Eventually the dolerite falls because it is unsupported and the process starts again

  4. The retreat of the waterfall upstream as a result of this process has left behind a steep sided gorge
• In the middle and lower sections of the River Tees the river flows over flat, low-lying land
• Meanders form such as in the area to the south-east of Darlington
• In the middle and lower sections floodplains and levées also form as a result of repeated flooding of the areas