formation of waterfalls and V shaped valleys

Question 1

What is a V-shaped valley?

Answer 1

• when a river is near its source, it often develops a v-shaped valley as the river erodes down (this is called a vertical erosion)
• at the same time, weathering breaks up material on the valley slopes
• weathered material from the valley sides gets deposited in the river
• this material is carried by the river and erodes the riverbed through abrasion

Question 2

What are waterfalls?

Answer 2

• waterfalls often form in the upper stages of a river where it flows over different bands of rocks
• it erodes soft rock more quickly than hard rock and this may lead to the creation of a waterfall

Question 3

Formation of a waterfall

Answer 3

• the soft rock erodes more quickly, undercutting the hard rock
• the hard rock is left overhanging and because it isn’t supported, it eventually collapses
• the fallen rocks crash into the plunge pool. They swirl around causing more erosion
• over time, this process is repeated and the waterfall moves upstream
• a steel-sided gorge is formed as the waterfall retreats

Question 4

Meander Bend

Answer 4

• a meander is a bend in the river
  meanders usually occur in the middle or lower course and are formed y erosion and deposition
• as the river flows around a meander, centrifugal forces cause the water to flow fastest around the outside of the bend