Geology and rivers

Zerkalo

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I always liked Geology as part of Geography at school as I was already into fishing and so found the bits about rivers interesting.

What I've learned recently from fishing the Severn is that sometimes you don't get what you expect. Yesterday I fished a peg that was wider AND deeper than other pegs on the same stretch. Basic geology tells me the ground must be softer here and so it has cut out a hole. Is that a fair assessment?

It is still strange though, how the river goes fast, slow, wide, narrow, deep, shallow, and variations of that all within a few miles.

On canoeing from Bridgnorth to Arley I noticed it, but I think I'm more tuned into it when fishing.

When I told my brother in law I was fishing Quatford, he said "oh yeah, that's where the sandstone cliffs are" and it turns out he's right although I haven't seen them in two meadows there when fishing so presume you have to walk further for those.

Sandstone_cliff_at_Quatford_-_geograph.org.uk_-_1547211.jpg

That kind of sandstone is pretty common in the area with loads of it around my village of Kinver, but I think the geology of the middle Severn Valley is quite varied so that's why you get a river with so many features.

I presume a lot of other rivers in their upper and middle reaches do the same as the Severn?
 

MarkW

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I've never heard a satisfactory explanation for Cromwell's Hole on the Arley stretch, one of the deepest river spots I've seen.

My local Dorset Stour is clay vale in the upper reaches, fed by chalkstreams further downstream and tends to be deeper upstream, often with a clay river bed, than the mostly shallower lower reaches which are more gravelly. There is Ham stone near the river up near Marnhull though I've rarely encountered it on the river.

Down on the tidal Dorset Frome there is a sandstone cliff just below Wareham which used to be prominent but now hidden behind trees and bushes.

I have come across Cotswold stone in the bed of the upper Thames just above Newbridge although again that area is mostly clay bedded. A lot of the river gravel on the upper Thames is limestone (Cotswold stone) rather than the flint that we get in Dorset (Bagshot Beds).
 

Zerkalo

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Other than Cromwell's Hole, Arley is renowned for having nice fast shallow runs as well, so it's even more remarkable how quickly it changes all within the same stretch! That's what I find remarkable, as the only explanation I can think of is having a different bottom, as there must be a great difference in volume of water that goes through there, which is not always apparent by the speed of the flow or the width of the river.

Interesting to hear about the other rivers too.
 

Zerkalo

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Geology can be a bit nerdy but I find it interesting. I have a mate who is still at university in his 30s having not finished about 3 different courses, he's settled on Geology and is already working for a Geology department of some firm. My brother in law is full of facts about the history of places too. When I mentioned The Danery on the Severn he told me that it gets its name because of something to do with being invaded and settled by Denmark, I forget the exact story, something to do with Vikings. And just looking that up, I saw on the Wiki page for Quatford, it's in the video game Assassin's Creed 'Valhalla' - I might have to play that. :LOL:
 

Blanks

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I fish two rivers the Bristol Avon and the Hampshire Avon and they are as different as chalk and cheese apart from a couple of areas like Lacock Abbey fields and Limpley Stoke.
 

Sam Vimes

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The river I fish most (in the areas I fish it) is a combination of bedrock (mostly limestone), boulders, cobbles and gravel in varying amounts. Barring the bits where bedrock is particularly prevalent, you can't rely on the river staying the same from year to year. Regular spate flooding can alter depths very quickly. In areas that aren't constrained (by bedrock or artificially), it's not remotely unusual for the course of the river to alter overnight. Even in parts of the river that do sit between artificial course constraints, it regularly breaches them and occasionally destroys them completely.
 

tunna

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that photo of the cliffs looks like the ones opposite Knowle sands No 3 meadow, just below white house bend
 

Zerkalo

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I remember seeing some cliffs when I went canoeing but couldn't remember where I saw them, haven't seen them when fishing yet.
 

Silverfisher

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Quite an interesting subject that. All I know about the Thames is that above Oxford it’s mostly quite gravelly bottomed then once you get to Oxford it goes mostly quite sandy bottomed.
 

Zerkalo

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Quite an interesting subject that. All I know about the Thames is that above Oxford it’s mostly quite gravelly bottomed then once you get to Oxford it goes mostly quite sandy bottomed.
I've always had the Thames in your area down as a slow paced river, is that about right?

This part of the Severn I was on yesterday evening, so slow and wide I could have been forgiven for thinking I was much further down. But further below that you have fast stretches, so I think a lot is down to geology.
 

Silverfisher

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I've always had the Thames in your area down as a slow paced river, is that about right?

This part of the Severn I was on yesterday evening, so slow and wide I could have been forgiven for thinking I was much further down. But further below that you have fast stretches, so I think a lot is down to geology.
Yep is indeed pretty slow. Most places are a nice trotting pace but others hardly move.

I should think flow is a combination of geology and gradient plus how many locks and marinas you’ve got for the water to spread into.
 

smiffy

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I remember seeing some cliffs when I went canoeing but couldn't remember where I saw them, haven't seen them when fishing yet.
Golf course at Bridgenorth? I may well be wrong but I’m sure I was sitting opposite some cliffs there.
 

Zerkalo

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Golf course at Bridgenorth? I may well be wrong but I’m sure I was sitting opposite some cliffs there.
I think this time canoeing is the only time I've been out of the car at Bridgnorth, it's where we set off from. I should explore both Bewdley and Bridgnorth a bit more as they seem nice places but just not had reason to in the time I've lived round here.
 

smiffy

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I think this time canoeing is the only time I've been out of the car at Bridgnorth, it's where we set off from. I should explore both Bewdley and Bridgnorth a bit more as they seem nice places but just not had reason to in the time I've lived round here.
I used to like staying in Bridgenorth. Bewdley? Dodgy after the boozers had opened😉😂
 
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