TOPIC 1B: River landscapes and processes 🌊

Question 1

What type of gradient does the upper course of a river have?

Hint: begins with s

Answer 1

• the upper course of a river, has a steep gradient

Question 2

What type of gradient does the lower course of the river have ?

Hint: what letter begins with g?

Answer 2

Gentle gradient

Question 3

What type of gradient does the middle course of a river have?

Hint: M

Answer 3

• the middle course of a river, has a medium gradient

Question 4

What are the two types that erosion can be?

Hint: vertical + _______.

Answer 4

• vertical
• lateral

Question 5

Can you explain what lateral erosion does?

Hint: widens the _____ valley and

Answer 5

• lateral erosion, widens the river valley [and channel], during the formation of meanders.
• ; [it’s dominant in the middle and lower course].

Question 6

Can you explain what vertical erosion does?

Hint: deepens the … valley
Hint #2: what shape?

Answer 6

• deepens river valley (and channel) making it v-shaped.
• [dominant in the upper course of the river + high turbulence causes the rough, angular particles to be scraped along the river bed, which causes downwards erosion].

Question 7

Can weathering shape river valleys ?

Answer 7

Yes

Question 8

Suggest how mechanical weathering could shape a river in the valley course [4]

Hint: freeze-thaw, WIRE

Answer 8

• water in the cracks of rocks freezes and expands- which puts pressure on the rock.
• water thaws, and it contracts and releases pressure on the rock
• repeated freezing + thawing widens crack, and causes rock to break up.
• therefore this makes rockfall more likely, and this changes the shape of the valley side.

Question 9

What are two ways, that mass movement can influence river landscapes ? [3]

Hint: undercutting of a slope

Answer 9

• mass movement, is when gravity causes the movement of material down a slope
• a river could erode the base of a valley, and could cause undercutting of slope.
• mass movement can add large amounts of material to river’s load.

Question 10

What are four reasons, why rivers slow down and deposit material? [4]

Hint: shallower

Answer 10

• Any from:
• volume of water in the river falls
• amount of eroded material in the water increases.
• water is shallower [e.g- inside of a bend]
• the river reaches its mouth.

Question 11

Fill in the gaps:

Landscapes with more resistant rocks tend to have _______ valley sides.

Landscapes with less resistant rock tend to have gentle ______ valley sides.

Answer 11

• Landscapes with more resistant rocks tend to have steeper valley sides.
• Landscapes with less resistant rock tend to have gentle sloping valley sides.

Question 12

Explain how a waterfall is formed. 💧

Hint: quicker than, undercut, plunge, collaspes, retreats, gorge

Answer 12

• soft rock is eroded quicker than the hard rock and this creates a step.
• and as erosion continues, the hard rock is undercut- which forms an overhang.
• abrasion and hydraulic action then erode to create a plunge pool
• and over time, this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses.
• this process continues and the waterfall retreats upstream.
• and finally, a steep-sided valley is left where the waterfall once was. [a gorge]

Question 13

Explain how interlocking spurs are formed [3]

Hint: upper course, harder to erode and

Answer 13

• interlocking spurs are formed because:
• in the upper course, there is more vertical erosion
• the river cuts down into the valley, and if there are areas of hard rock which are harder to erode, the river will bend around it.
• This then creates interlocking spurs of land [which link the land together]

Question 14

Explain how meanders are formed. [5]

Hints: current of water, high-energy environment, low energy environment, eroded material deposited + material builds up.

Answer 14

• the current of the water is faster on the outside of the bend because the river channel is deeper
• this means the outside of the bend is a high-energy environment, which means more abrasion and hydraulic action take place. (This forms steep-sided river cliffs).:
• inside of bend is a low-energy environment + the current is slower because the river channel is shallower.
• So eroded material deposits on inside of bend
• over time, material builds up to form a point bar

Question 15

Explain how an oxbow lake is formed [3]

Hint: outside bends, breaks through, deposition cuts off…

Answer 15

• an oxbow lake is formed because:
• erosion causes outside bends to get closer, until there’s only a small bit of land left
• the river then breaks through this land (typically during a flood), and the river then flows along the shortest course
• ; deposition, now eventually cuts off the meander and this forms an oxbow lake.

Question 16

What is a floodplain ? [1]

Answer 16

• a floodplain, is a flat area of land that floods

Question 17

What are levees ?

Answer 17

• levees are natural embankments

Question 18

How are floodplains formed? [2]

Hint: deposition and…

Answer 18

• floodplains are formed, due to both erosion and deposition.

Question 19

How are levees formed ? [3]

Hint: flood, slows down and material builds up

Answer 19

• during a flood, eroded material is deposited over a whole flood plain
• the heaviest material is deposited closest to the river channel because, it gets dropped first when the river slows down
• ; over time, deposited material builds up and creates levees, along the edges of the river channel

Question 20

RECAP: How are igneous rocks formed?

Answer 20

• igneous rocks are formed, by magma from the [Earth’s] mantle, cooling down and then hardening.
• this rock also contains crystals as it cools.

Question 21

What’s another way, mass movement can influence landscapes ?

Hint: likely to occur- saturated with water

Answer 21

• mass movement is more likely to occur, when valley sides are saturated with water, after rain or flooding.
• This is because, water acts as a lubricant [making the valley sides slippery and material heavier]

Question 22

What’s another way, how mass movement can influence landscapes ?

Hint: loosened by…

Answer 22

• weathering can increase likelihood of mass movement.
• This is because, when material is loosened by weathering, it’s held together more weakly.