Waterfalls and Gorges Flashcards

1
Q

How do rivers erode in the upper course?

A

Rivers erode mainly downwards - vertically

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2
Q

When do Waterfalls occur? - Step 1

A

When a river crosses a bed of more resistant rock

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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
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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
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5
Q

When the less resistant rock is eroded what happens? - Still STEP 3

A
  • A ledge is created which overhangs and eventually collapses
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6
Q

How is a gorge then formed?

A
  • As the waterfall takes up a new position, leaving a gorge
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