Waterfalls and Gorges Flashcards
1
Q
How do rivers erode in the upper course?
A
Rivers erode mainly downwards - vertically
2
Q
When do Waterfalls occur? - Step 1
A
When a river crosses a bed of more resistant rock
3
Q
What happens after the river crosses this bed? - Step 2
A
- Erosion of the less resistant rock underneath undercuts the hard rock above it
- The river’s energy creates a hollow at the foot of the waterfall, known as plunge pool
4
Q
What happens in Step 3 of a waterfall forming?
A
- The LESS resistant rock beneath is eroded more rapidly by arbasion and hydraulic action
5
Q
When the less resistant rock is eroded what happens? - Still STEP 3
A
- A ledge is created which overhangs and eventually collapses
6
Q
How is a gorge then formed?
A
- As the waterfall takes up a new position, leaving a gorge
