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rivers - physical geography > Waterfalls > Flashcards

Flashcards in Waterfalls Deck (16)
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1
Q

the formation of a waterfall

A

a river crosses a bed of more resistant rock

2
Q

the formation of a gorge

A
  • erosion of less resistant rock underneath undercuts the hard rock
  • this occurs by abrasion (water has lots of rock in it) and hydraulic action (from the force of falling water)
  • the rivers energy creates a hollow at the base of the waterfall - a plunge pool
  • erosion continues and creates a ledge of hard work which overhangs and collapses
  • the process is repeaters again and again and the gradual retreat of the waterfall forms a steep sided gorge or valley, which may retreat over time
3
Q

where is the fastest flow in a river

A

on the outside bend

4
Q

how would you describe the flow of a river

A

helical

5
Q

what is the fastest current called

A

thalweg

6
Q

define permeable rock

A

water can’t penetrate into the rock causing the river discharge to be lower

7
Q

define impermeable rock

A

water can penetrate into the rock causing the discharge to be higher

8
Q

rural

A

less discharge - nature soaking up the water

9
Q

deforestation

A

interception doesn’t happen - increases river discharge

10
Q

urban

A

lots of concrete - greater discharge

11
Q

antecedent rainfall

A

rain for a long time. increases river discharge

12
Q

heavy rain, melting snow

A

increases river discharge

13
Q

hot, dry weather

A

more evaporation - less river discharge. makes ground impermeable when rains. increases surface run off

14
Q

extreme cold

A

frozen ground - impermeable. increased run off

15
Q

steep slopes

A

steeper the ground increases run off and river discharge

16
Q

gentle slopes

A

decreases river discharge and run off - ground isn’t steep