waterfalls and gorges

Question 1

What to waterfalls leave in their wake as they retreat back up the valley?

Answer 1

A gorge

Question 2

What is the first step in the formation of a waterfall?

Answer 2

The water of a river runs over a band of more resistant rock, which has a band of less resistant rock below it

Question 3

What is the second step in the formation of a waterfall?

Answer 3

The less resistant rock erodes quicker than the more resistant rock, which means undercutting and the formation of a plunge pool occur

Question 4

What is the third step in the formation of a waterfall?

Answer 4

The continued undercutting means that the more resistant rock overhangs the less resistant rock. This becomes two heavy to be supported, so the rock collapses into the plunge pool below

Question 5

What is the fourth step in the formation of a waterfall?

Answer 5

The water continues to undercut the more resistant rock (by eroding the less resistant rock) so the third step repeats. This means the waterfall retreats back up the valley, forming a gorge