Where goes rift off GG main chamber ?

[JasonC]

If you enter GG main chamber from the direction of Bar Pot (say) and cross directly to the far side, you come to a large boulder slope. About two-thirds up this, against the right-hand wall is a an attractive rift passage heading steeply down. I had a look down there yesterday, but got to a point where the descent was nearly vertical.
I stopped here, but the passage clearly went on, and I could hear water below. There also looked to be a possible way much higher up the rift.
A pile of bang wire(?) was in evidence, but it's been there some time.

Does anyone know where this leads, if anywhere?

 

[Lankyman]

It's a while since I was in there but I have poked my face into a few pretty obvious passages on the northern side of Main Chamber. Do you have a copy of the old Northern Caves Vol 3 (Ingleborough)? It sounds like you could have been in West Fissure which leads to a hundred foot pitch. Or possibly West Pot (described as at the top of West Slope).

 

[JasonC]

Thanks Lankyman. I have the 1996 NC2, but the description of West Fissure does match what I saw, so I think you're right. Is there really a hundred foot pitch down from there, though? I must have already got to the level of the main chamber floor.
One fine day, I'll have to revisit with some rope...

 

[Ian Ball]

I thought West Fissure and West Pot were different

 

[ChrisB]

enter GG main chamber from the direction of Bar Pot (say) and cross directly to the far side

Just checking for possible confusion. I read that as meaning coming out of South Passage and across the chamber to East Slope. To reach West Slope you'd go to the far end, not the far side.

 

[alanw]

Is there really a hundred foot pitch down from there, though? I must have already got to the level of the main chamber floor.

Ground penetrating radar has been used in the main chamber. See Investigating the nature and origins of Gaping Gill Main Chamber, North Yorkshire, UK, using ground penetrating radar and lidar
There is strong evidence for sedimentary structures down to at least 30m below the floor of GGMC.

 

[alanw]

Above is a thumbnail survey of the main chamber, taken from Ind Meredith(1975) Gaping Gill. North is to the top. To the east is East Slope, leading to Mud Hall. The passage in the middle bottom is South Passage. north-west of it are the waterfall and the landing of the winch, with North Passage to their right. To the left is West Slope, note the "p26" to the north of its end.

 

[Pitlamp]

JasonC - you said: "If you enter GG main chamber from the direction of Bar Pot (say) and cross directly to the far side, you come to a large boulder slope."

When I first read this I assumed you were referring to North Passage, which is straight across from where you emerge from South Passage (the usual entry point if you're en route from Bar Pot). I was briefly quite excited as it had me wondering if recent floods had opened up something new!

The useful survey which alanw provided above makes all clear. I think the "P26" is West Pot and the fissure immediately to the right (east) of this is West Fissure. West Fissure is an obvious fissure but the passage leading to West Pot starts as a very short bedding plane with a small drop into a bigger area, soon leading to the pitch. (From memory there is also a way on over West Pot; I think NCC members climbed into it many years ago but it didn't go.) The pitch at West Pot is very wide (and a bit loose, incidentally), whereas West Fissure is tight. (There is an account of its discovery in a BPC publication).

The water at the bottom of West Fissure flows into a sump and then emerges shortly after at the base of the West Pot pitch. So both would have the sound of falling water (depending to some extent on the conditions) The short sump was first passed by BPC / CDG members.

It does sound as if you were at either West Pot or West Fissure - if so you'd have walked ALONG Main Chamber from South Passage, rather than going across it.

 

[Lankyman]

When I first read this I assumed you were referring to North Passage, which is straight across from where you emerge from South Passage (the usual entry point if you're en route from Bar Pot). I was briefly quite excited as it had me wondering if recent floods had opened up something new!

Has North Passage ever been pushed any further than what's described in my 1981 Ingleborough guide? It seems to be heading under the surface course of Fell Beck.

 

[Alex]

I went down that P26 in the top left corner of that survey about 12~ months ago, I think it had anchors, I can't remember what kind maybe petzl. I only just reached the bottom thinking it was only 20m deep for some reason. It seems to go on at the bottom, I scrambled down a slope at the bottom, but there was too much water falling down. I think on a drier day it might go somewhere...? Worth digging if it don't though, it's a just a dry weather dig I would guess.

 

[alanw]

JasonC - you said: "If you enter GG main chamber from the direction of Bar Pot (say) and cross directly to the far side, you come to a large boulder slope."

When I first read this I assumed you were referring to North Passage, which is straight across from where you emerge from South Passage (the usual entry point if you're en route from Bar Pot). I was briefly quite excited as it had me wondering if recent floods had opened up something new!

There is a fissure straight across from South Passage, between the waterfall and North Passage. It's just beyond where the coral fossil is in the short length of wall running north/south (ish). It's seen some investigation/digging, but I don't know how deep it goes.

 

[Pitlamp]

Has North Passage ever been pushed any further than what's described in my 1981 Ingleborough guide? It seems to be heading under the surface course of Fell Beck.

There are various surveys in CPC publications which may help answer your question. (I'm not sure which publication you're referring to which has your 1981 description; could you please tell us?)

A rudimentary one (CPC Journal 6 [6]) here:

http://cavemaps.org/surveys/cpc/full/CPC%20J6-6%20North%20Passage%20GG.png

. . . and a much better one (CPC Record 20) here:

http://cavemaps.org/surveys/cpc/full/CPC%20R20%20Gaping%20Gill%20-%20North%20Passage.png

There is also this useful drawing (from CPC Record 4) which pre-dates your 1981 guide:

http://cavemaps.org/surveys/cpc/full/CPC%20R4%20Gaping%20Gill%20-%20North%20Passage.png

 

[Pitlamp]

I went down that P26 in the top left corner of that survey about 12~ months ago, I think it had anchors, I can't remember what kind maybe petzl. I only just reached the bottom thinking it was only 20m deep for some reason. It seems to go on at the bottom, I scrambled down a slope at the bottom, but there was too much water falling down. I think on a drier day it might go somewhere...? Worth digging if it don't though, it's a just a dry weather dig I would guess.

Assuming this is West Pot, here's a quick description. My memory is that the pitch is 27 m deep. It slopes slightly and the wall you (used to) go down (on ladders) is loose, due to a lot of fault breccia. Immediately at the bottom a lot of water gushes in on the right (originating from West Fissure) - this assumes you have your back towards the sloping wall of the pitch you've just descended.

To the immediate left some of the water disappears into a badly choked vertical rift. In normal to wetter conditions the rest of the water enters a rift in the far left corner of the pitch base. This descends steeply via several easily climbed but loose drops and eventually ends at a small sump pool (which is static in dry conditions). Underwater the passage descends steeply to -6 m where it meets a restriction. Just beyond there is a minor enlargement and then the underwater passage becomes too small. (Somewhere in a caving diary I have a sketch elevation on this sump; PM me if you want me to copy it for you but I doubt it's help much unless you plan on diving it again.)

We did consider digging the choked rift on the left of the pitch base where all of the water sinks in dry conditions. Several aspects led to our pursuing projects elsewhere though:

1. It's only be workable in dry conditions (although it might be possible to send the water down the sloping rift leading to the sump described above.

2. It seemed likely that flooding woulod simply fill it in again between digging trips.

3. Perhaps most importantly - it's on the opposite side of the Main Chamber from where the water goes (Mud Pot phreas and then South East Pot / South East Pot Extension sumps). So a breakthrough at West Pot would probably just lead to a pitch down to a sump pool, soon blocked by the massive chokes forming the floor of the Main Chamber.

But . . . as they say "Caves is where you find 'em".
So don't hold back purely on the above less than encouraging information!

 

[Lankyman]

There are various surveys in CPC publications which may help answer your question. (I'm not sure which publication you're referring to which has your 1981 description; could you please tell us?)

A rudimentary one (CPC Journal 6 [6]) here:

http://cavemaps.org/surveys/cpc/full/CPC%20J6-6%20North%20Passage%20GG.png

. . . and a much better one (CPC Record 20) here:

http://cavemaps.org/surveys/cpc/full/CPC%20R20%20Gaping%20Gill%20-%20North%20Passage.png

There is also this useful drawing (from CPC Record 4) which pre-dates your 1981 guide:

http://cavemaps.org/surveys/cpc/full/CPC%20R4%20Gaping%20Gill%20-%20North%20Passage.png

Thanks, Pitlamp. It looks as though North Passage has seen a fair bit of attention. Unsurprising, given its location and ease of access? The 1981 guide I have is the NC Vol 3 Ingleborough (2nd edition) which is the most up-to-date version I have. Do you have any ideas where the passage is heading? Would it have been a sink further up Fell Beck perhaps?

 

[Pitlamp]

North Passage has traditionally been a winch meet job, when the access is very easy!

Where's it heading? Now there's a question. It's clearly very old (possibly even pre-Anglian). So unlikely to be related to sinks in what we currently know as Fell Beck as this is very near the top of the Great Scar Limestone and Main Shaft / Lateral Shaft / Rat Hole are relatively recently formed.

There is this intriguing idea that it goes right under Ingleborough to some long inactive and planed off ancient sink, somewhere in an early version of Chapel-le-Dale . . . . (Other contenders for this are the North West Extension beyond Stream Chamber and the blocked "upstream" end of the mega tunnel in Hurnell Moss Pot; both also clearly very old.)

The GG system still holds a great many secrets!

 

[Lankyman]

North Passage has traditionally been a winch meet job, when the access is very easy!

Where's it heading? Now there's a question. It's clearly very old (possibly even pre-Anglian). So unlikely to be related to sinks in what we currently know as Fell Beck as this is very near the top of the Great Scar Limestone and Main Shaft / Lateral Shaft / Rat Hole are relatively recently formed.

There is this intriguing idea that it goes right under Ingleborough to some long inactive and planed off ancient sink, somewhere in an early version of Chapel-le-Dale . . . . (Other contenders for this are the North West Extension beyond Stream Chamber and the blocked "upstream" end of the mega tunnel in Hurnell Moss Pot; both also clearly very old.)

The GG system still holds a great many secrets!

Now a through trip from GG to Chapel-le-Dale would be an order greater than Dowbergill! I've also wondered about Hurnel Moss since seeing its black line survey on the same page as GG/Ingleborough Cave and well away from everything else.

 

[Pitlamp]

I forgot to mention - the average trend of many of the faults / joints in the limestone is NW/SE.

The same trend is known to exist in the ridges and valleys at the top of the pre-Carboniferous basement below the limestone (although this is not necesarily too relevant when considering ancient passages).

These facts make the suggestion of an ancient route under the mountain a reasonable possibility, at least.

 

[JasonC]

JasonC - you said: "If you enter GG main chamber from the direction of Bar Pot (say) and cross directly to the far side, you come to a large boulder slope."

When I first read this I assumed you were referring to North Passage, which is straight across from where you emerge from South Passage (the usual entry point if you're en route from Bar Pot). I was briefly quite excited as it had me wondering if recent floods had opened up something new!

The useful survey which alanw provided above makes all clear. I think the "P26" is West Pot and the fissure immediately to the right (east) of this is West Fissure. West Fissure is an obvious fissure but the passage leading to West Pot starts as a very short bedding plane with a small drop into a bigger area, soon leading to the pitch.

Thanks for all the comments, and apologies for any confusion. In my mind, when you get down into main chamber from SE Passage, you're looking along the length of the chamber, so the far side is the far end, towards the West.
Anyway, I'm now sure I was in West Fissure, as the entrance was right against the right wall of the slope going up, and it was a very tall, narrow rift, not a bedding plane, so presumably not heading to the P26 in West Pot. So, what's at the bottom of that?

 

[Pitlamp]

Thanks for confirming.

One of my posts above says: "The water at the bottom of West Fissure flows into a sump and then emerges shortly after at the base of the West Pot pitch.". Does that answer the question immediately above?

Anyway, it looks like we've got to the bottom of this one between us.

 

[Alex]

Thanks for the info Pitlamp, I presume I was trying to climb down those loose climbs but the amount of water stopped me descending to see the sump.