11.3 Changing cross-profiles of a river

Question 1

What is a cross profile

Answer 1

Shows a cross-section of a river’s channel and valley at a certain point along the river’s course

Question 2

W

Question 3

What is the river’s cross profile like in the middle course

Answer 3

There is some vertical erosion but more lateral erosion. The channel is wider and deeper as a result

Question 4

What is the river’s cross profile like in the lower course

Answer 4

There is a lot less erosion, with only some lateral erosion. The channel is at its widest and deepest

Question 5

What is the valley like in the upper course

Answer 5

Steep sided, narrow and deep V-shaped vary. River channel takes up most of the valley floor

Question 6

What is the valley like in the middle course

Answer 6

Valley broadens out. It now has a small flood plain. Valley sides are not as deep

Question 7

What is the valley like in the lower course

Answer 7

Large expanse of flat flood plain either side of the river

Question 8

How do the characteristics of a river and its valley change?

Answer 8

Upper course:
- in an upland area, it has the power to erode downward as it is way a.s.l. and forms a V-shaped valley
- as the gradient of the valley decreases, the river uses its energy to transport the material it has eroded
Middle course:
- due to the lack of gradient, it begins to erode laterally. As it moves closer to sea level, the gradient decreases further
Lower course:
- although the river is still eroding sideways, deposition is the most important process and the valley becomes wider and flatter