Mossdale Beck

[Antwan]

Excellently put 'Pitlamp' 

Interesting...only 30 minutes for a flood pulse to pass through the waterway of such a hugely extensive cave system as Gaping Gill - Ingleborough Cave......

would that mean, given the speed of sound reference there is only just over 300m of passage between the two, or that there must be a significant sink closer than fall beck give that I think it has gotta be more than that distance accross the surface. 

 

[TheBitterEnd]

Not necessarily because it may not be phreatic and hydraulically locked all the way. There may be air bells and joints etc that allow the pulse to travel at slower speeds for some of the distance. Also remember that that length and volume of water will not be the ideal incompressible fluid.

 

[Pitlamp]

Excellently put 'Pitlamp' 

Interesting...only 30 minutes for a flood pulse to pass through the waterway of such a hugely extensive cave system as Gaping Gill - Ingleborough Cave......

would that mean, given the speed of sound reference there is only just over 300m of passage between the two, or that there must be a significant sink closer than fall beck give that I think it has gotta be more than that distance accross the surface.

Sorry Antwan - I've read this a couple of times and I'm not entirely sure what you're asking.

Keep things simple - assume that the pulse is transmitted through a sump instantaneously and that it travels along vadose passages pretty slowly. Yes, the reality is more complex but keeping things simple is probably more useful than getting bogged down in minutiae.

I'm not sure how well you know the GG system but, in a nutshell, here's what probably happens. Fell Beck hurls itself down Main Shaft then continues steeply or vertically down through the sediment floor and enters the phreas as soon as it leaves the Main Chamber fault. It then probably flows in deeply submerged fault guided passages passing below the downstream sump in Stream Passage Pot, passing close by the base of the South East Pot sump, then at or close to the bottom of the very deep sumps in Lost River Chamber (plumbed to -37 m). I think it then enters the deep tunnel in the upstream section of the Deep Well sump (at over -40 m in places), then flows into the downstream section of Deep Well and is lost in chokes.

It then emerges from the massive breakdown on the floor of Ingleborough Cave's Sump 4 before rising to surface (for a few metres only) then passing through Sumps 3, 2 and 1 to surface properly for the first time at Terminal Lake. So virtually the whole of its journey from GG Main Chamber to Ingleborough Cave is phreatic - and often deeply phreatic. It then flows as a short streamway between Terminal Lake and the Wallows where it sumps again. This sump ends where the stream surfaces in the Secret Stream Passage from where another short section of streamway conveys the water to the next phreatic section between Lake Pluto and Beck Head Stream Cave. There is then a final short streamway leading to the resurgence at Clapham Beck Head.

Cavers who aren't really familiar with the off the beaten track parts of both GG and Ingleborough Cave may not easily have followed the above! The point I'm making is that there's only three short sections of streamway between Gaping Gill Main Chamber and Clapham Beck Head and the rest is deep phreas in very large passages. This is why dye can take a fortnight to pass through in dry conditions whereas a sudden flood pulse can emerge from Clapham Beck Head in as little as 30 minutes after the pulse hit GG.

Does that help?

 

[peterk]

I think there is some confusion about "pulse" - visible water movement .v. a pressure wave as in Sonar, water hammer in plumbing.

 

[richardg]

Hey "Pitlamp". That's a great price of writing there.... Your description of the Fell Beck river's journey makes me think I'd like to be a diver too... Wow! what a journey you've taken us on there...

 

[Antwan]

I was bored at the other half's parents and started bashing numbers into a calculator. (and I got my numbers slightly wrong)

This quote from langcliff: Transmission of a pressure pulse through a phreatic tube is almost instantaneous (at the speed of sound), by ford and williams is what I was number crunching.

If the fastest transmission is (to keep it simple) 1500ms-1, and a flood pulse takes 1800 seconds then there is a minimum of 1200meters  of passage. and given that GG main shaft is just over a mile away then that all works out well.

where I went wrong was calculating 300m of passage,  already knowing (but in no where near as much detail as you!) most of it is flooded passage started musing about an undiscovered major sink!

Sorry for been a bit bored  and getting my sums wrong

 

[Pitlamp]

Antwan's comment about an "undiscovered major sink" is relevant because of course Clapham Beck Head is fed by other medium sized sinks (P5, Stream Passage Pot) and umpteen minor ones. So the model I gave above (relating just to Fell Beck) is obviously an over-simplification. Really I was just trying to illustrate the principle of pulse transmission speed in phreatic & vadose situations, to help readers understand the significance of Richard's original post.

Here's another thought to cogitate on; is "flooded" the best choice of word to describe the long GG sumps? We all do it - but have these sumps ever not been underwater passages? The reason I mention this is because I'm involved in helping to proof read the fantastic new Part 2 of the Dales book by Tony Waltham et al. and this point has led to some interesting discussions! (My argument is that "flooded" implies a passage was once dry but has since become water-filled. I think it's worth making the distinction because there are certain cases where sumps actually are flooded passages - the classic example being large areas of the KMC to Keld Head phreas where the water level was once at least 7.2 m lower than today - as indicated by underwater flowstones down to that depth.) Maybe I should get today's pedant award?  :-\

 

[Badlad]

By co-incidence there is a piece in the forthcoming Descent Magazine on Ken Ashton's hydrological experiments.  He reported two tests between Marble Steps Pot and Keld Head in different flow conditions.  The pulse travelled at different speeds through the cave in the different conditions.  His results led him to conclude that in wet conditions around '400 yards' of passage was flooded which in drier conditions had airspace.  It is a conclusion which has given hope to diggers and divers in the area for 40 years.

 

[Pitlamp]

Absolutely right Badlad.

It's perhaps worth noting that it was only just over a decade before Ken Ashton's mid 60's pulse tests that cavers finally sorted out the true destination of the Marble Steps stream. Many cavers even after the war believed that MSP drained to Leck Beck Head, a reasonable assumption as LBH is lower that Keld Head. This was in the days when folk weren't quite so sensitive about colouring streams. So the miscreants concerned lobbed 5.45 kilograms (!) of fluorescein into MSP. Apparently the result was reasonably convincing!

The reference for this test is in the Cave Research Group Newsletter (July / October 1954 edition).

 

[Antwan]

Pitlamp, You are a mine of information. Or at least where to get it!

I wish I could say thanks by guarding the Malham sump or something similar one day but working full time and studying for a degree has reduced my free time some what.

Thanks 

 

[langcliffe]

Nor should we forget that Ashton predicted the presence of vadose passage between the base of Rowten Pot and Keld Head...

An artificial flood pulse was used by the YGS as early as 1879 to confirm a flood connection between Tarn Sinks and Malham Cove. The flood pulse took 85 minutes to reach Aire Head, but 130 minutes to emerge from the Cove which is less than half the distance. Presumable the delay in arrival at  Maham Cove is due to the water having to back up from the start of the phreas before being able spill over into a conduit which emerges at the base.

 

[andys]

An artificial flood pulse was used by the YGS as early as 1879 to confirm a flood connection between Tarn Sinks and Malham Cove. The flood pulse took 85 minutes to reach Aire Head, but 130 minutes to emerge from the Cove which is less than half the distance. Presumable the delay in arrival at  Maham Cove is due to the water having to back up from the start of the phreas before being able spill over into a conduit which emerges at the base.

Which - though absolutely nothing to do with the original post! - suggests the presence of vadose cave above the eventually phreas which resurges at Aire Heads, with a connection to a higher level passage which leads through to the Cove Rising. Now, if memory serves, this upper passage is also fed from the Smelt Mill sinks (which water only emerges at the cove I think) suggesting this higher level passage is also vadose and flows downhill from its connection point which the main Tarn Sinks to Aire Heads route? An interesting test would be to set off a pair of flood pulses - the first to "fill" the cave, and then the second to test if there is still a delay in arrival at both the two risings - but I don't know how practical that might be! Just a thought 

 

[martinm]

some great posts in this thread by some very knowledgeable people.  May help me with some of my intended water tracing this winter... 

 

[richardg]

Mel....... We hope your use of the flood pulse will lead you to proving the Hamps - Manifold Master Cave with miles of vadose river passages 

Richard

 

[martinm]

Mel....... We hope your use of the flood pulse will lead you to proving the Hamps - Manifold Master Cave with miles of vadose river passages 

Richard

Ta Richard. Difficult to dam the rivers to create a flood pulse, but am thinking Pepper Inn sink (Back of Ecton) and Gateham & Plantation to Ilam. (Pretty sure the last one goes to Ilam already. Just need to test it properly.) An artificial flood pulse with a bit of dye (Fluorescein) would do the job nicely I think! The flood pulse would help the dye get through a lot quicker, will get my BCRA research grant application in quick and might be able to get the research done this winter...

 

[braveduck]

To create a flood pulse in those conditions,get one or more one ton  builders bags line with polythene and fill with water.
Then collapse or cut open quickly .That should do the job !You will need enough people to hold the bags up while they are
being filled .

 

[Bottlebank]

To create a flood pulse in those conditions,get one or more one ton  builders bags line with polythene and fill with water.
Then collapse or cut open quickly .That should do the job !You will need enough people to hold the bags up while they are
being filled .

... whilst exercising a little care as to where you stand presumably?

 

[Fulk]

... whilst exercising a little care as to where you stand presumably?

Definitely!

I once set out to do a combined fluoroscein-cum-flood pulse test in Short Gill Cave, Barbondale, and we made a dam using huge sheets of polythene.

The plan was that we should synchronize watches and I would dash (!; insofar dashing is possible in SGC) out to get to the putative resurgence before the others released the dam.

I got to the resurgence just in time to see a flood-pulse come through several minutes before the appointed time. Some time later, I was accosted by a very irate bunch of cavers who had had to cope when the dam burst prematurely; they claimed they were all almost dragged into the sump, but I think that they were exaggerating. One of them had the presence of mind to add the fluoroscein as he was clinging on with one hand to a stall (well, so he said), so we then hung around fort the dye to appear . . . . which it did, with a vengeance, an hour or two later. When it had reached the bridge just below the big house in the tress and coloured the whole beck green for hundreds of metres, we decided it was time to beat a hasty retreat.

Still, we showed that the flood-pulse was transmitted pretty well instantaneously, while the dye took a bit longer to come through.

 

[droid]

I seem to vaguely recall several fluoricine/rhodamine related mishaps in the late '70s.....

Plus a rather embarassing sump removal exercise that shook the Drum and Monkey in Swales.....

 

[grahams]

Back at Mossdale Beck, I have questions, questions, questions:

Back in the 60s/70s I have a vague memory that Mossdale Beck sank for a while some distance upstream of Mossdale Scar. Has anyone attempted to re-discover this old sink and was the water seen within the Caverns, possibly in the Far North? Is it possible that the water went not to MC but into the far reaches of Langcliffe Pot? Looking at Cavemaps, it seems possible that the latter was the case - there's even a line of miner's scratchings running in a line from the end of Langcliffe to the area near the shooting hut upstream of Mossdale.

Has the water in Stream End Cave, Black Edge Pot, Black Edge Shakehole and How Gill been dye tested and if so what were the results? I seem to remember speculation that the water might go to Low Mill giving a depth potential of almost 1300 feet for the Langcliffe/Mossdale system.

Where does Spring Trap Cave/White Keld fit into all this?