Waterfalls

Question 1

the formation of a waterfall

Answer 1

a river crosses a bed of more resistant rock

Question 2

the formation of a gorge

Answer 2

• 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

Question 3

where is the fastest flow in a river

Answer 3

on the outside bend

Question 4

how would you describe the flow of a river

Answer 4

helical

Question 5

what is the fastest current called

Answer 5

thalweg

Question 6

define permeable rock

Answer 6

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

Question 7

define impermeable rock

Answer 7

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

Question 8

rural

Answer 8

less discharge - nature soaking up the water

Question 9

deforestation

Answer 9

interception doesn’t happen - increases river discharge

Question 10

urban

Answer 10

lots of concrete - greater discharge

Question 11

antecedent rainfall

Answer 11

rain for a long time. increases river discharge

Question 12

heavy rain, melting snow

Answer 12

increases river discharge

Question 13

hot, dry weather

Answer 13

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

Question 14

extreme cold

Answer 14

frozen ground - impermeable. increased run off

Question 15

steep slopes

Answer 15

steeper the ground increases run off and river discharge

Question 16

gentle slopes

Answer 16

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