river landscapes

Question 1

waterfall

Answer 1

sudden steep drop in a river.
formed:
1) the soft rock is eroded quicker than the hard rock and this creates a step
2) as erosion continues, the hard rock is undercut forming an overhang
3) abrasion and hydraulic action continue to erode the soft rock to create a plunge pool (small scale landform)
4) over time this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses
5) this process continues and the waterfall retreats upstream
6) a steep-sided valley is left where the waterfall once was. This is called a gorge

Question 2

abrasion

Answer 2

when rocks carried by the sea water wear away the landscape, eg cliff face/headland

Question 3

hydraulic action

Answer 3

erosion caused by the force of river water hitting cracks in the side of the river bank. the air in the cracks becomes compressed and then explodes outwards, breaking off bits of rock

Question 4

gorge

Answer 4

a deep, narrow passage that usually has a river running through it

Question 5

plunge pool

Answer 5

the pool of water found at the bottom of a waterfall. it is an erosional feature which has been created by a combination of hydraulic action and the abrasion of the plunging water

Question 6

v shaped valley

Answer 6

in the upper course there is more vertical erosion as the river is less powerful, so material cannot be moved in suspension and is instead moved along the river bed using traction or saltation. this erosion, together with the movement of weathered material at the sides of the river, creates the classic V-shaped valley. if there are areas of hard rock which are harder to erode, the river will bend around them

Question 7

suspension

Answer 7

a mixture of two substances, one of which is finely divided throughout the other

Question 8

meanders

Answer 8

the river gains more energy when it gets to the middle course, so material can be carried in suspension and is used to erode river banks. lateral erosion widens the river, when the river flows over flat land it develops a large bend called a meander.

Question 9

formation of meander

Answer 9

• as a river goes around a bend, most of the water is pushed to the outside which causes increased speed due to less friction, so erosion is increased
• lateral erosion on the outside of a bend causes undercutting of the river bank to form a river cliff
• there’s less water on the inside bend of a meander so friction causes the water to slow down, lose energy and deposit material the river was carrying to create a gentle slope
• the build-up of deposited sediment is known as a slip-off slope or river beach

Question 10

river cliff

Answer 10

a steep bank created on the outside of a river bend by the erosive effect of fast-flowing water undercutting the bank

Question 11

floodplain

Answer 11

a lower course landform. a flat area of land that is covered in water when a river bursts its banks, formed due to deposition and erosion.