Johnpeters
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Vertical erosion is dominant here as the river is trying to get to its base level due to gravity and so the abrasion and hydraulic action that occurs is predominantly on the bed rather than the banks

Vertical erosion is dominant here as the rocks here are too large to be carried in a suspended load and so bedload is transported by traction and saltation which therefore erodes the bed more than the banks. Coupled with this, as the river has a lower velocity this further exaggerates the traction and saltation.

Are both these statements correct for the upper course? (AS geog)
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tgwktm
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(Original post by Johnpeters)
Vertical erosion is dominant here as the river is trying to get to its base level due to gravity and so the abrasion and hydraulic action that occurs is predominantly on the bed rather than the banks

Vertical erosion is dominant here as the rocks here are too large to be carried in a suspended load and so bedload is transported by traction and saltation which therefore erodes the bed more than the banks. Coupled with this, as the river has a lower velocity this further exaggerates the traction and saltation.

Are both these statements correct for the upper course? (AS geog)
i would say the first one is correct, but i am unsure on the second one, what you have said about how larger rocks are transported in the upper course is correct, but i don't think it relates to vertical erosion
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TheStudent18
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(Original post by Johnpeters)
Vertical erosion is dominant here as the river is trying to get to its base level due to gravity and so the abrasion and hydraulic action that occurs is predominantly on the bed rather than the banks

Vertical erosion is dominant here as the rocks here are too large to be carried in a suspended load and so bedload is transported by traction and saltation which therefore erodes the bed more than the banks. Coupled with this, as the river has a lower velocity this further exaggerates the traction and saltation.

Are both these statements correct for the upper course? (AS geog)
The first statement is correct, but I am unsure about the second statement. The rule is that rivers in their upper course have more vertical erosive power due to gravity (as you said) and as they progress downstream, the discharge of the river increases as does its lateral erosive power resulting in the river becoming wider.

Also, you have said "as the river has a lower velocity this further exaggerates the traction and saltation". What do you mean by this? Remember that traction is the sliding movement of sediment (normally rudaceous/coarse in size exceeding 2mm in diamter) and so a relatively high energy is required and whilst low velocities generally means less energy, enough energy is generated for the movement of this load. However, in the upper course you can also assume that the transport medium of gravity is acting here so whilst low energy conditions could result from the low water velocities, the gradient of the river is likely to be steep (as its upper course) so gravity is likely to be a factor here also aiding the movement of the load.

You are however correct in saying that traction and saltation erodes the river bed due to abrasion. But again, I am not entirely certain about the second statement so maybe someone else may be able to help you further or maybe have a look at online geographical related websites?
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