Author Topic: Longest Cave in Britain?  (Read 3557 times)

Offline oldboy

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Longest Cave in Britain?
« on: April 20, 2011, 08:12:53 pm »
The recently published BCRA Caves & Karst Science (Vol. 38 N0.1) describes Ogof Draenan as the longest cave in Britain.  Is this a true statement?

The Three Counties System must surely be a serious contender.

Offline JasonC

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Re: Longest Cave in Britain?
« Reply #1 on: April 20, 2011, 08:31:22 pm »
I've often wondered how caves are measured - is every little poxy dead-end counted ?  What about the common situation where there's a stream passage with a little oxbow as an alternative route - are both sections counted ?
And is the length of a passage taken from a centre line (whatever that is), or along side walls ?

I'm just curious - it's a bit like the question of how long is the coastline of Britain - which depends significantly on the size of 'ruler' you use to measure it.  Presumably similar considerations apply to caves....  :-\

Offline paul

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Re: Longest Cave in Britain?
« Reply #2 on: April 20, 2011, 08:53:46 pm »
Is it not simply surveyed length? Add up all survey legs and that gives you the length.
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Offline mmilner

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Re: Longest Cave in Britain?
« Reply #3 on: April 20, 2011, 09:19:32 pm »
Is it not simply surveyed length? Add up all survey legs and that gives you the length.

Yes, absolutely. An oxbow is a separate passage to the main stream passage. How short should a 'dead end' passage be before it becomes 'poxy' in your opinion? There are very few 'dead end' passages in natural caves, (only mines), the passages normally either get too small to negotiate or end in boulder chokes. (Which might be passed by future digging anyway.)

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Offline TheBitterEnd

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Re: Longest Cave in Britain?
« Reply #4 on: April 21, 2011, 07:28:56 am »
The same measurement problem occurs with any rough surface, the finer the detail of the measurements the longer the length, consider measuring the coastline...

Anyway this whole "longest cave" seems a bit daft to me in the way it is presently done. I can't help but think that Britain can only claim cave systems in the longest 20 or 30 in the world because they are amongst the most diligently explored. Obviously the extent of the system is of interest scientifically and gives some idea of whether it will fill an evening or a weekend but would some measure based on the longest route* be most useful?

Do capped/blasted passages count as cave or mine :-\


*by "longest route" I suppose I have in mind traversable passage that doesn't involve back-tracking except on the way out, so dead-ends and branches do not count.
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Offline Alex

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Re: Longest Cave in Britain?
« Reply #5 on: April 21, 2011, 11:55:31 am »
Provided the capping and blasting is not making an entirely new passage and only enlarging a passage then I would class it as part of the cave, as it is still part of the cave only now it is large enough for a human to fit in.

As for you longest trip idea, I do not think that would work because conceivably a trip could take in every side passage and oxbow making it the total length of a cave. I know you said only trips that go from one point to another but a place like Ease gill could have 100s of these so it would be too complicated to work out. In some caves however maybe a main route length would be useful.

One thing I do think they should change is to change the total lengths to NOT include passage behind none free dive-able sumps, which have no dry access route. This is not part of a cave us normal people could set foot in.

Those lengths still be mentioned but along side the total length maybe in brackets or something.
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Offline TheBitterEnd

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Re: Longest Cave in Britain?
« Reply #6 on: April 21, 2011, 12:03:15 pm »

"normal people" ... that's a whole new can of worms ;D
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Offline Alex

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Re: Longest Cave in Britain?
« Reply #7 on: April 21, 2011, 12:05:46 pm »
Bad choice of words perhaps, by normal I mean those without 1000s of quid to spend on diving equiptment and perhaps who are a little bit mad lol.

I would not dive underground, but hats off to those that do. But that does not stop me thinking you are quite mad lol.
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Offline graham

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Re: Longest Cave in Britain?
« Reply #8 on: April 21, 2011, 01:15:51 pm »
The argument as to how to measure the length of a cave has been going on for years and will probably never have a final resolution BUT it is important that every single oxbow and side passage is included as this should ensure that the surveyors don't skimp on the job.

Alex, with very few exceptions, cave divers are actually perfectly normal people.
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Offline JasonC

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Re: Longest Cave in Britain?
« Reply #9 on: April 21, 2011, 02:43:57 pm »
Is it not simply surveyed length? Add up all survey legs and that gives you the length.

Yes, absolutely. An oxbow is a separate passage to the main stream passage. How short should a 'dead end' passage be before it becomes 'poxy' in your opinion? There are very few 'dead end' passages in natural caves, (only mines), the passages normally either get too small to negotiate or end in boulder chokes. (Which might be passed by future digging anyway.)
Well, 'too small to negotiate' equates to 'dead end' in my book.  Ok, a passage might be passed in future, but if it's only passable by an underfed rat now, is it right to add its length to the cave total ?

Likewise, imagine the not uncommon situation where a passage is split in two by some obstruction.  Does the fact that you can go round either side mean you can count that section of passage twice ?  If the surveyor can be bothered to record both parts separately, then apparently you can - although it doesn't make the passage any longer when you actually negotiate it.

I just wonder what statements like 'Easegill has 30km of passage' (or whatever the current figure is) actually mean ?

TBE's suggestion of 'longest traversible route' seems better, but as Alex says in a complex system, that would be tricky to calculate.  Perhaps 'longest sensible traversible route' ?  Oh, forget it....  :'(

Offline JohnMCooper

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Re: Longest Cave in Britain?
« Reply #10 on: April 21, 2011, 03:56:41 pm »
I found the following statement made by John Stevens in 1996 with relation to the Ogof Draenen surveying:

I have now calculated the true length of Ogof Draenen using the international criteria for cave length.
 

To calculate the length, I created a table with each row representing either 1 page of the grade 5 note or a grade 2 file.  For each row several figures needed to be calculated:-

a)   Centreline length from the figures page of the notes (frequently done over several pages, i.e. 1 trip)

b)   Extra centreline length from diagram page, if added to centreline.(Note.  a+b = centreline length normally quoted. i.e. survex length.)

c) & d)  Number of legs in the same manner as a) & b).

e)   Extra passage length from diagram page not already accounted for.

f)   Grade 1 noted in the diagram page but not drawn.

g)   Duplicate centreline lengths.  Mainly extra traverses around chambers or along far sides of wide passages, spokes on a chamber survey, extra distances at acute bends etc.

h)   Junction widths.  The spur to a side passage does not count as length as set by the international criteria.

i)   Grade 2 centreline length from the grade 2 files.

j)   Grade 2 length already accounted for in a) to h).

The length is then calculated by a+b+e+f+i-g-h-j.


The current length of Draenen(25.11.1996) is about 53.75km., vertical range 148m.  This includes 2km. for the new OUCC find, Dollimore Series, which goes off The Last Sandwich.  More is expected from this area.

Not sure what/if there is a current figure.

Offline graham

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Re: Longest Cave in Britain?
« Reply #11 on: April 21, 2011, 04:15:07 pm »
Not sure what/if there is a current figure.

The Cambrian Cave Registry gives a length of 80000 m but no depth. It is clear that this figure has measured with a great deal of precision. ;)

The ukcaves database gives 70 km. This is the current top ten on that list:

1   Ogof Draenen   length 70 km depth   151 m   South Wales
2   Lancaster - Easegill - Pippikin - Lost John's   60   211   Northern Dales   
3   Ogof Ffynnon Ddu   50   308   South Wales   
4   Agen Allwedd   32.5   160   South Wales
5   Ogof Daren Cilau System   28   232   South Wales
6   Kingsdale Master Cave   27   165   Northern Dales   
7   Clearwell Caves   24   107   Forest Of Dean   
8   Ireby Fell Cavern - Notts Pot - Large Pot - Rift Pot   23.4   183
9   Peak Cavern - Speedwell Cavern   17.59   248   Peak District
10   Gaping Gill System   16.9   197.5   Northern Dales   
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Offline Ed W

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Re: Longest Cave in Britain?
« Reply #12 on: April 21, 2011, 04:39:47 pm »
In truth the length of a cave is whatever the surveyor says it is!  That is to say that, as has already been mentioned, as the cave is not regular then the surveyed length will depend to some degree on the individual surveyor's methods.  Even following the above rigorous methods adopted for Ogof Draenen I am sure that if it was re-surveyed by another team that the length they arrived at would be different due to different selection of stations etc - the question is how different I guess.  Perhaps a subject for a dissertation...

To my mind, with the surveys I have done, my attitude is that the length is a far from precise figure (though my "guidelines" are pretty close to those described for Ogof Draenen, though I suspect that there is a little more "artistic license" in the way I use them).  At best it is a useful guide to the approximate extent of a cave system.  Finally, if anyone wants to argue with my stated surveyed length, they are more than welcome to go and measure the cave themselves - I am sure they will do a better job of it than I can!
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Offline paul

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Re: Longest Cave in Britain?
« Reply #13 on: April 21, 2011, 04:42:12 pm »
Is it not simply surveyed length? Add up all survey legs and that gives you the length.


Yes, absolutely. An oxbow is a separate passage to the main stream passage. How short should a 'dead end' passage be before it becomes 'poxy' in your opinion? There are very few 'dead end' passages in natural caves, (only mines), the passages normally either get too small to negotiate or end in boulder chokes. (Which might be passed by future digging anyway.)

Well, 'too small to negotiate' equates to 'dead end' in my book.  Ok, a passage might be passed in future, but if it's only passable by an underfed rat now, is it right to add its length to the cave total ?

Likewise, imagine the not uncommon situation where a passage is split in two by some obstruction.  Does the fact that you can go round either side mean you can count that section of passage twice ?  If the surveyor can be bothered to record both parts separately, then apparently you can - although it doesn't make the passage any longer when you actually negotiate it.

I just wonder what statements like 'Easegill has 30km of passage' (or whatever the current figure is) actually mean ?

TBE's suggestion of 'longest traversible route' seems better, but as Alex says in a complex system, that would be tricky to calculate.  Perhaps 'longest sensible traversible route' ?  Oh, forget it....  :'(


What does it matter if there is or isn't 'longest traversible route' available? The 'longest length' figures are surveyed length and give an indication of the total size of a system. A very complicated system with lots and lots of passages and junctions might have a very long surveyed length yet only be a short distance across. Another simpler system might only have one or two long passages and the distance covered by the system would be very large.

Compare Knock Fell Caverns: the scale on the survey shown suggests that the cave is a few hundred metres from one end to the other yet the length is given as 4.5 Kilometres.


I'm not a complete idiot: some parts are missing!

Offline Pitlamp

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Re: Longest Cave in Britain?
« Reply #14 on: April 21, 2011, 05:52:55 pm »
I get people telling me I'm mad for being an underwater potholer - whilst they're smoking a fag.

Who's mad? No offence to all the smokers out there; just kind of suggesting that before people imply something is dangerous they might usefully do a realistic risk assessment instead of requoting popular myths.  ;)


If passages beyond sumps don't "exist", why was there such interest when the Shuttleworth Pot dig broke into Witches Cave in October last year?

Offline Alex

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Re: Longest Cave in Britain?
« Reply #15 on: April 21, 2011, 06:26:07 pm »
I think smokers are mad too.

And cavers, I am living proof of that one!

I take it when you venture into Knock Fell Caverns a ball of string is handy? I take it that place is more mine then cave?
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Offline JasonC

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Re: Longest Cave in Britain?
« Reply #16 on: April 21, 2011, 07:34:00 pm »
John MC - thanks for that post - if all the cave length calculations are carried out as conscientiously as that, then I can see they do give a fair measure.

Paul - fair comment!  Hard to know what would be a sensible figure to give for something like KFC.  Hats off to the poor sods who surveyed it!

Offline Anon

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Re: Longest Cave in Britain?
« Reply #17 on: April 21, 2011, 07:45:31 pm »
I take it when you venture into Knock Fell Caverns a ball of string is handy? I take it that place is more mine then cave?
Most certainly not! The proper survey is actually very good and can be used to navigate round without too many problems. And it's all cave. Good fun, crap walk up though lol.

Offline Alex

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Re: Longest Cave in Britain?
« Reply #18 on: April 21, 2011, 10:26:27 pm »
Seems like good fun and its in Yorkshire too. Did not realize that. That reminds lattice configuration reminds me of Storrs cave, only Storrs is a lot smaller (for now at least)

Anyway I digress and will stop going off topic now.
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Offline AndyF

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Re: Longest Cave in Britain?
« Reply #19 on: April 22, 2011, 10:48:30 am »
Does it really matter...?

I know people get very territotial about deepest/longest etc. but the cave is the same irrespective of measurement method.

Visit it, enjoy it, explore it ...but don't do it just because of a place on a list... ;D
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Offline Alex

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Re: Longest Cave in Britain?
« Reply #20 on: April 22, 2011, 01:07:50 pm »
It only matters on shorter caves bit pointless to drive 50 miles to a cave and find its 20m long lol.
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Offline Peter Burgess

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Re: Longest Cave in Britain?
« Reply #21 on: April 22, 2011, 05:19:36 pm »
It only matters on shorter caves bit pointless to drive 50 miles to a cave and find its 20m long lol.
It never stopped JRat, judging by what he logged in his diaries. But then he was always on the lookout for a good dig.
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Offline TheBitterEnd

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Re: Longest Cave in Britain?
« Reply #22 on: April 22, 2011, 06:22:37 pm »
Seems like good fun and its in Yorkshire too. Did not realize that. That reminds lattice configuration reminds me of Storrs cave, only Storrs is a lot smaller (for now at least)

Anyway I digress and will stop going off topic now.

It's in WESTMORLAND (like all the best caves)  :tease:
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