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Why is there more vertical erosion in the upper course of a river?

Hi, I've just started AS geography, and was just reading the textbook and wasn't sure to why this happened.

Why is there more vertical erosion in the upper course, and more lateral erosion in the lower course?

Thanks :smile:

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Isn't it because the gradient is Steeper in the upper course, and the velocity of the river is slower? Then vice versa for the lower course.
Reply 2
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MedicalMayhem
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Original post by Chicharito14
Isn't it because the gradient is Steeper in the upper course, and the velocity of the river is slower? Then vice versa for the lower course.


And how does that explain my question? :confused:
Original post by MedicalMayhem
And how does that explain my question? :confused:


The sediment is larger and heavier, which erodes the river bed, hence why you get features like waterfalls etc.

Then with the lower course of the river, the sediment erodes to smaller particles, meaning the particles are lighter, and instead of eroding the river bed, they erode the sides.

This is because the velocity of the river is higher in the lower course, and the fastest flow of a river is on the outer bend of a river. This is why you get meanders etc.

This is the best answer i could give you lol.
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Original post by Chicharito14
The sediment is larger and heavier, which erodes the river bed, hence why you get features like waterfalls etc.

Then with the lower course of the river, the sediment erodes to smaller particles, meaning the particles are lighter, and instead of eroding the river bed, they erode the sides.

This is because the velocity of the river is higher in the lower course, and the fastest flow of a river is on the outer bend of a river. This is why you get meanders etc.

This is the best answer i could give you lol.


Erm okay. And also, I've read (like you said) that there is a faster flow at the outer bend of a meander, hence more deposition on the inside bend. And so there is meander migration, etc.. But why is there a faster flow at the outer bend of a meander?
Original post by MedicalMayhem
Erm okay. And also, I've read (like you said) that there is a faster flow at the outer bend of a meander, hence more deposition on the inside bend. And so there is meander migration, etc.. But why is there a faster flow at the outer bend of a meander?


Because that is is the fastest flow of a river.

I can't really explain it to you lol.

Oh yeah, due to erosion, if you look at a cross action of a river, the inside of a bend, is far shallower, than the outside of a bend, meaning more water (and sediment) can pass through the outside of the bend which will cause further erosion.

Its all to do with the depth of the riverbed; if you can find a cross section of a river, it will help explain that to you, if not, have a look online to see if there is any other explanations.
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Original post by Chicharito14
Because that is is the fastest flow of a river.

I can't really explain it to you lol.

Oh yeah, due to erosion, if you look at a cross action of a river, the inside of a bend, is far shallower, than the outside of a bend, meaning more water (and sediment) can pass through the outside of the bend which will cause further erosion.

Its all to do with the depth of the riverbed; if you can find a cross section of a river, it will help explain that to you, if not, have a look online to see if there is any other explanations.


Okay, meander bit makes sense, but I'll just take it as a given then (for the vertical erosion bit) :/
Reply 7
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I think I know the vertical erosion bit, it's because the rocks haven't been eroded yet, they fall to the bottom of the river and get all churned up by the flow, grinding away at the river bed and eroding vertically through abrasion or whatever it's called.
Original post by MedicalMayhem
Okay, meander bit makes sense, but I'll just take it as a given then (for the vertical erosion bit) :/


Sorry about the help, wasn't the greatest aha, got rid of my geography textbooks last month.
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Original post by Chicharito14
Sorry about the help, wasn't the greatest aha, got rid of my geography textbooks last month.


Haha :smile: So you dropped Geography after your AS? If you don't mind, but how did you do in it?
Reply 10
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Original post by MedicalMayhem
Erm okay. And also, I've read (like you said) that there is a faster flow at the outer bend of a meander, hence more deposition on the inside bend. And so there is meander migration, etc.. But why is there a faster flow at the outer bend of a meander?


Because there is more water, a large wetted perimeter (compared to the inside) which means less friction.. also it's a v shaped valley because the water cuts through the rock as it is continuously pounding against it if that makes sense lol, I'm taking as geo too, how to you find it?
Original post by MedicalMayhem
Haha :smile: So you dropped Geography after your AS? If you don't mind, but how did you do in it?


No I've just started uni haha. Erm i got an A at Geography A level.

I've literally forgotten a lot of stuff to do with geography over the summer haha.

In my AS, i got an A in geography, then for A levels, i was literally like 10 UMS marks over the boundary required for an A, so I'm not complaining :colone:
Original post by V95
Because there is more water, a large wetted perimeter (compared to the inside) which means less friction.. also it's a v shaped valley because the water cuts through the rock as it is continuously pounding against it if that makes sense lol, I'm taking as geo too, how to you find it?


It's alright, I prefer my other 'sciency' subjects though. I'm taking Biology, Chemistry, Maths and Geography, what about you?

I find that the AQA textbook for Geography is not very thorough, and though it may well get you through the course with a good grade, it's frustrating for me as often it just wants you to 'learn that something happens' rather than to understand why something happens.
Reply 13
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Original post by MedicalMayhem
It's alright, I prefer my other 'sciency' subjects though. I'm taking Biology, Chemistry, Maths and Geography, what about you?

I find that the AQA textbook for Geography is not very thorough, and though it may well get you through the course with a good grade, it's frustrating for me as often it just wants you to 'learn that something happens' rather than to understand why something happens.


Im taking the same subjects as you!! lol, I have the same problem too, my school doesn't use the aqa specific as our main text, we use one by a dude called Skinner - i prefer it soo much, its easier to understand, then we just quickly go through the aqa one to make sure we haven't missed anything out!
Original post by MedicalMayhem
It's alright, I prefer my other 'sciency' subjects though. I'm taking Biology, Chemistry, Maths and Geography, what about you?

I find that the AQA textbook for Geography is not very thorough, and though it may well get you through the course with a good grade, it's frustrating for me as often it just wants you to 'learn that something happens' rather than to understand why something happens.


Ah, you are taking AQA geography...

If you want to get an A grade for geog, you need the Barker (brown covered book) book, which helps massively.

costs around £20
Original post by V95
Im taking the same subjects as you!! lol, I have the same problem too, my school doesn't use the aqa specific as our main text, we use one by a dude called Skinner - i prefer it soo much, its easier to understand, then we just quickly go through the aqa one to make sure we haven't missed anything out!


Are you talking about this book? http://www.amazon.co.uk/AQA-AS-Geography-Students-Guide/dp/0340946113/ref=sr_1_1?ie=UTF8&qid=1317573006&sr=8-1 (just searched it up on Amazon :tongue:) As if it is, I may well invest in it :smile: So are there more diagrams, and more well-explained key terms?

Which boards are you taking for your subjects? I'm doing Edexcel Biology, AQA Geography + Chemistry, OCR Maths + Critical Thinking :smile: Critical Thinking + Biology on the Wednesday, and Maths + Chemistry on the Friday (January exams) :s-smilie: How are you finding the workload in general?
Reply 16
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Original post by Chicharito14
Ah, you are taking AQA geography...

If you want to get an A grade for geog, you need the Barker (brown covered book) book, which helps massively.

costs around £20


I have that one!! just mentioned in haha, its by skinner too ;]
Original post by Chicharito14
Ah, you are taking AQA geography...

If you want to get an A grade for geog, you need the Barker (brown covered book) book, which helps massively.

costs around £20


This one, http://www.amazon.co.uk/AQA-AS-Geography-Students-Guide/dp/0340946113/ref=sr_1_1?ie=UTF8&qid=1317573006&sr=8-1 ?
Reply 18
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Original post by MedicalMayhem
Are you talking about this book? http://www.amazon.co.uk/AQA-AS-Geography-Students-Guide/dp/0340946113/ref=sr_1_1?ie=UTF8&qid=1317573006&sr=8-1 (just searched it up on Amazon :tongue:) As if it is, I may well invest in it :smile: So are there more diagrams, and more well-explained key terms?

Which boards are you taking for your subjects? I'm doing Edexcel Biology, AQA Geography + Chemistry, OCR Maths + Critical Thinking :smile: Critical Thinking + Biology on the Wednesday, and Maths + Chemistry on the Friday (January exams) :s-smilie: How are you finding the workload in general?


Yes it is that one!! Yep, i find it much easier to understand, even the diagrams, the aqa one i feel includes things which aren't too necessary to learn!

I'm doing maths with edexcel and geo chem and maths with aqa! I'm finding the workload quite heavy, i think its just my etcher though, he's rather extra :P how out you? what career do you wanna go into?
Original post by V95
Yes it is that one!! Yep, i find it much easier to understand, even the diagrams, the aqa one i feel includes things which aren't too necessary to learn!

I'm doing maths with edexcel and geo chem and maths with aqa! I'm finding the workload quite heavy, i think its just my etcher though, he's rather extra :P how out you? what career do you wanna go into?


Ah thanks for that recommendation, so you'd say it's much more complicated to understand? What do you mean by things that are not necessary to learn?

I'm finding the workload heavy as well as I do extra reading for each subject :/ Wait, you've done a typo I suspect, maths with edexcel or aqa? :redface: But chemistry was slightly difficult with the concept of electronegativity, but it seems alright now. Where are you up to? We're just starting molecular calculations (having done subshells and most of bonding/electronegativity :smile: ) But the biochemistry in biology looks quite difficult, and especially how one of my teachers just goes off topic in every lesson :/

Does my username not give it away? :rolleyes: ...Medicine :d

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