1.3-River landscapes Flashcards Preview

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Flashcards in 1.3-River landscapes Deck (50)
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1

What are 2 physical processes that shape a river?

weathering and mass movement

2

What are the 3 types of weathering?

mechanical
chemical
biological

3

What is biological weathering?

Roots growing and animals burrowing into cracks in rocks causing them to split apart.

4

What is chemical weathering?

slightly acidic rainwater dissolves rocks

5

What is mechanical weathering?

freeze thaw action

6

What is the process of freeze thaw action?

water fills a crack
water freezes and the crack widens
repeated action increases the size of the crack
loose blocks if rocks are called scree

7

What are 2 processes of mass movement?

sliding and slumping

8

What is sliding?

where rock or material moves down a slope under the influence of gravity

9

what is slumping?

Where the river erodes the bottom of the valley slope causing the rock to become saturated and slump/collapse, making the slope steeper.

10

What does slumping cause?

material to slide downwards particularly if it's saturated with rainwater

11

What is hydraulic action?

where the force of the water of the bed and banks removes material

12

What is attrittion?

the load that is carried by the river bumps together and wears down into smoother pieces

13

what is solution?

some minerals dissolving in river water

14

What is abrasion?

material carried by the river rubs against the bed and banks

15

What are the 4 main types or river transportation?

traction
salatation
suspension
soloution

16

What is it when large boulders are rolled along the river bed?

traction

17

What is it when smaller pebbles are bounced along the river bed?

salatation

18

What is it when finer sand and silt particles are carried along in the flow?

suspension

19

What is it called when some minerals are dissolved in the water and carried along in the flow?

solution

20

What shows how a river changes from source to mouth?

The Bradshaw model

21

what are charectaristics of the upper course of rhe river?

steep gradient
small discharge
shallow depth
narrow steep sides
fast velocity

22

What are some charectaristics characteristics of the middle course?

shallower gradient
large discharge
deeper depth
flatter channel shape
fast velocity

23

What are some charectaristics of the lower course of a river?

shallow gradient
very large discharge
deep depth
fast velocity

24

What features are formed in the upper course?

waterfalls
interlocking spurs

25

What features are formed in the lower course?

meanders
floodplain
leeves
ox bow lakes

26

What features are formed in the middle course?

meanders
floodplains

27

What increases the frequency of storms?

more periods of heavy rain and overflowing rivers

28

What increases the risk of flooding?

frequency of storms
periods of hot dry weather
soil becoming inpermeable during cold conditions

29

how are waterfalls formed?

The soft rock erodes more quickly, undercutting the hard rock.

The hard rock is left overhanging and because it isn’t supported, it eventually collapses.

The fallen rocks crash into the plunge pool. They swirl around, causing more erosion.

Over time, this process is repeated and the waterfall moves upstream.

A steep-sided gorge is formed as the waterfall retreats.

30

how are gorges formed?

over time this undercutting process is repeated and the waterfall retreats