Water On The Land

Question 1

What is the long profile?

Answer 1

Shows how the gradient changes of the different courses of a river.

Question 2

What is the cross profile?

Answer 2

Shows what the cross section of a river looks like.

Question 3

Characteristics of the upper course?

Answer 3

Steep, v-shaped valley, steep sides, narrow, shallow channel.

Question 4

Characteristics of the middle course?

Answer 4

Medium gradient, gently sloping valley sides, wider, deeper channel.

Question 5

Characteristics of the lower course?

Answer 5

Gentle gradient, very wide, almost flat valley, deep channel.

Question 6

What do vertical and lateral erosion change?

Answer 6

The cross profile of a river.

Question 7

What does vertical erosion do to the cross profile of a river?

Answer 7

It deepens the river valley and channel, making it v-shaped. It’s dominant in the upper course of a river.

Question 8

What does lateral erosion do to the cross profile of a river?

Answer 8

It widens the river valley and channel. It’s dominant in the middle and lower courses.

Question 9

What are the four processes of erosion?

Answer 9

Hydraulic action
Abrasion
Attrition
Solution

Question 10

What is hydraulic action?

Answer 10

When the force of the water breaks rock particles away from the river channel.

Question 11

What is abrasion?

Answer 11

When eroded rocks picked up by the river scrape and rub against the channel, wearing it away. Most erosion happens by abrasion.

Question 12

What is attrition?

Answer 12

When eroded rocks picked up by the river smash into each other and break into smaller fragments. Their edges also get rounded off as the rub together.

Question 13

What is solution?

Answer 13

When river water dissolves some types of rock. E.g. Chalk and limestone.

Question 14

What are the four processes of transportation?

Answer 14

Traction
Saltation
Suspension
Solution

Question 15

What is traction?

Answer 15

When large particles like boulders are pushed along the river bed by the force of the water.

Question 16

What is saltation?

Answer 16

When pebble-sized particles are bouncing along the river bed by the force of the water.

Question 17

What is suspension?

Answer 17

When small particles like silt and clay are carried along by the water.

Question 18

What is solution?

Answer 18

When soluble materials dissolve in the water and are carried along.

Question 19

What is deposition?

Answer 19

When a river drops eroded material.

Question 20

Why does deposition occur?

Answer 20

When a river slows down.

Question 21

What are the reasons for a river slowing down?

Answer 21

The volume of water in it falls.
The amount of eroded material in the water increases.
The water is shallower - the inside of a bend.
The river reaches it’s mouth.

Question 22

How are channels and valleys formed?

Answer 22

Rivers form channels and valleys as they flow downhill. They erode the landscape, then transport the material to somewhere else as it is deposited.

Question 23

When a rivers eroding and depositing material it can form?

Answer 23

Meanders and ox-bow lakes.

Question 24

Where are meanders formed?

Answer 24

In the middle and lower courses.

Question 25

How and why material is deposited on the outside of a bend?

Answer 25

The current is faster on the outside of the bend because the river channel is deeper. Less friction to slow the water down. More erosion takes place on the outside of the bend forming river cliffs.

Question 26

How and why is material deposited on the inside of the bend?

Answer 26

The current is slower on the inside of the bend because the river channel is shallower. There’s more friction to slow the water down. Material is deposited on the inside, forming slip - off slopes.

Question 27

How are ox-bow lakes formed?

Answer 27

When meanders get larger.
Erosion causes the outside bends to get closer until there’s only a bit of small land left. The river breaks through this land during a flood so the river flows along the shortest course. Deposition eventually cuts off the meander forming and ox-bow lake.

Question 28

How are waterfalls formed?

Answer 28

Form where a river flows over an area of hard rock followed by an area of softer rock. The softer rock is eroded more creating a step in the river. The water goes over the step and erodes it more and more.

Question 29

How is the plunge pool formed?

Answer 29

When the hard rock is eventually undercut by erosion. It becomes unsupported and collapses. The collapsed rocks are swirled around at the foot of the waterfall where they erode the softer rock by abrasion. Therefore creating a plunge pool.

Question 30

How is a gorge formed?

Answer 30

Over time when the water fall retreats due to more undercutting of the rock and more collapses. This leaves a steep sided gorge.