Draenen New Entrances
- Thread starter rhychydwr1
- Start date
Graigwen
Active member
Dudley Bug has drawn attention on another thread to the new 3D geology viewer from the BGS and reminded us that borehole details are available via the viewer. The I'r de o Draenen project has made extensive use of this information over the past two years but others interested in Ogof Draenen may not be aware of what is available.
On this site you can see the borehole log for the Pen Ffordd Goch borehole which entered unexplored cave passage in the Gilwern Oolite at a depth of -116m.http://scans.bgs.ac.uk/sobi_scans/boreholes/264325/images/10528274.html It is interesting to reflect that this borehole is close to a prominent depression on the roadside going up to Huntsman's car park. This depression looks just like a caprock collapse doline and lies above a straight line projection of the Big Country stream...but perhaps there is another explanation.
My favourite image from the borehole records of this area is one that shows Blaenavon looking like a Swiss cheese - how have we failed to enter these caves? http://scans.bgs.ac.uk/sobi_scans/boreholes/263697/images/10526498.html
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On this site you can see the borehole log for the Pen Ffordd Goch borehole which entered unexplored cave passage in the Gilwern Oolite at a depth of -116m.http://scans.bgs.ac.uk/sobi_scans/boreholes/264325/images/10528274.html It is interesting to reflect that this borehole is close to a prominent depression on the roadside going up to Huntsman's car park. This depression looks just like a caprock collapse doline and lies above a straight line projection of the Big Country stream...but perhaps there is another explanation.
My favourite image from the borehole records of this area is one that shows Blaenavon looking like a Swiss cheese - how have we failed to enter these caves? http://scans.bgs.ac.uk/sobi_scans/boreholes/263697/images/10526498.html
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alastairgott
Well-known member
Baker Street (page 19 of Borehole scan below) seems to have disappeared on modern maps, best I can find is James Street and William Street. https://goo.gl/maps/qnJVwccJnVR2
Graigwen said:
Graigwen
Active member
alastairgott said:
Yes, Baker Street has disappeared as a result of the development. It used to run NNE from approximately the middle point of Old William Street (i.e. halfway between Broad Street and Lower Hill Street) to James Street just beyond the point where the you can no longer drive a car (i.e. again halfway between Broad Street and Lower Hill Street. Capel Ebenezer stood on James Street facing down the northern end of Baker Street, the site is now a car park.
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Stuart France
Active member
Bore holes that are in downtown Blaenavon?
Surely the really interesting bore hole is the one that penetrated big passages roughly a hundred metres south west of the massive boulder choke at the southern end of Big Country and that's also reasonably well in line with the Into The Black choke?
Anyone know who owns all this open land on the Blaenavon side of the Fox Hunter Car Park road?
Surely the really interesting bore hole is the one that penetrated big passages roughly a hundred metres south west of the massive boulder choke at the southern end of Big Country and that's also reasonably well in line with the Into The Black choke?
Anyone know who owns all this open land on the Blaenavon side of the Fox Hunter Car Park road?
Graigwen
Active member
Stuart France said:
My former employers Norwest Holst drilled a load of shallow holes in Blaenavon as part of site investigation for new buildings etc. In my opinion none were very interesting to cavers. It is true that before paving a lot of water went into the ground, but this seems to to have been mainly down very narrow cracks in the Llanelli Formation.
The " really interesting bore hole" is the one I gave a link to earlier:-
"On this site you can see the borehole log for the Pen Ffordd Goch borehole which entered unexplored cave passage in the Gilwern Oolite at a depth of -116m.http://scans.bgs.ac.uk/sobi_scans/boreholes/264325/images/10528274.html It is interesting to reflect that this borehole is close to a prominent depression on the roadside going up to Huntsman's car park. This depression looks just like a caprock collapse doline and lies above a straight line projection of the Big Country stream...but perhaps there is another explanation."
The land ownership south of the road is a bit tricky. Some on the Torfaen side of the Gwent border is owned by Torfaen CB Council. Some land in an interesting position is apparently unregistered. I would guess further north Pwll Du Conservation Ltd own some. (I have written this from memory and will check my records tomorrow.)
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Stuart France
Active member
Not sure about this. The late Bill Gascoine told me that the "interesting" bore hole hit cave passage with air space some metres in height and sediment under that - but the BGS records here seem to show solid rock all the way to -140 metres, unless I'm missing something. If the surface is at 478m then this bore hole ends at 338m as it is 140m deep, which puts it into the right ballpark for Big Country / Into the Black. Perhaps Bill was talking about somewhere else.
Has anyone any explanation as to why Big Country is so flat? I mean, not on much of a gradient, when MS&D by contrast has got huge drops in it eventually ending up at Into the Black, which is also pretty flat by that stage. I suppose Big Country could drop dramatically where the south choke blocks the way on, giving a reason for why it is there.
To pass under the present river in Downtown Blaenavon, the cave would have to go well below 300m, assuming Big Country continues pretty much south, over a distance of approaching 2kms. It would need to lose another 50m (at least) in altitude relative to the bottom of the Pen Ffordd-Goch bore hole to do a "proper job" of tunneling underneath what is now the Afon Lwyd, which sounds feasible considering how much MS&D has managed to drop over only a 500m stretch.
Has anyone any explanation as to why Big Country is so flat? I mean, not on much of a gradient, when MS&D by contrast has got huge drops in it eventually ending up at Into the Black, which is also pretty flat by that stage. I suppose Big Country could drop dramatically where the south choke blocks the way on, giving a reason for why it is there.
To pass under the present river in Downtown Blaenavon, the cave would have to go well below 300m, assuming Big Country continues pretty much south, over a distance of approaching 2kms. It would need to lose another 50m (at least) in altitude relative to the bottom of the Pen Ffordd-Goch bore hole to do a "proper job" of tunneling underneath what is now the Afon Lwyd, which sounds feasible considering how much MS&D has managed to drop over only a 500m stretch.
Andy Farrant
Active member
Stuart
The BGS records for the Pen-fford-goch borehole show a 3.47 m high cavity at c. 120 m depth, which is at a level at or just below the base of the Gilwern Oolite at c. 360 m OD. Another sand-filled cavity 0.47 m high occurs a few metres lower at 122 m depth. This is at about the same elevation as the Elliptic-Nunnery-Squirrel Rifts series of passages. If memory serves me correct (?), the location of the borehole is probably just south of the squirrel rifts area (its on the survey I think, which I don't have to hand), so it is likely that the BH hit a passage associated with this maze network. The borehole is also written up in the Bulletin of the Geological Survey of Great Britain No. 67 1978 (Barclay and Jones) which is available online on the BGS website. http://pubs.bgs.ac.uk/publications.html?pubID=B04524. I recall some talk (heresay?) of a gamma logger being lost in this borehole, so it may be in the cave!
As for Big County - it's not totally clear how this bit of passage relates to the rest of the cave; I very much doubt the main conduit will continue south, but it probably fed into the Score-Gilwern Conduit at around 310 m OD link, a drop of around 30 m. Alternatively it may have joined the Indana Highway conduit at c. 340 m. THowever, the water in this bit of passage has since been captured down dip, like the Agent Blorenge streamway from Haggis Basher, and is probably a similar steeply descending vadose streamway - the 'Mystery streamway'. This will join the Beyond a choke stream somewhere downstream of the Riflemans choke, together with the stream in MS&D which is captured south in the Yellow Van area. The main MSD passage is a down-dip vadose passage graded to the Score-Gilwern Conduit at around 310 m OD.
The present Beyond a choke streamway will continue south beyond Riflemans, and may have led to a former resurgence at an elevation of c. 270 m in the Blaenavon area. The stream has since been captured into a lower level streamway which then flows beneath the Lwyd to the springs further downvalley.
Still huge potential in Draenen for lots more passage!
The BGS records for the Pen-fford-goch borehole show a 3.47 m high cavity at c. 120 m depth, which is at a level at or just below the base of the Gilwern Oolite at c. 360 m OD. Another sand-filled cavity 0.47 m high occurs a few metres lower at 122 m depth. This is at about the same elevation as the Elliptic-Nunnery-Squirrel Rifts series of passages. If memory serves me correct (?), the location of the borehole is probably just south of the squirrel rifts area (its on the survey I think, which I don't have to hand), so it is likely that the BH hit a passage associated with this maze network. The borehole is also written up in the Bulletin of the Geological Survey of Great Britain No. 67 1978 (Barclay and Jones) which is available online on the BGS website. http://pubs.bgs.ac.uk/publications.html?pubID=B04524. I recall some talk (heresay?) of a gamma logger being lost in this borehole, so it may be in the cave!
As for Big County - it's not totally clear how this bit of passage relates to the rest of the cave; I very much doubt the main conduit will continue south, but it probably fed into the Score-Gilwern Conduit at around 310 m OD link, a drop of around 30 m. Alternatively it may have joined the Indana Highway conduit at c. 340 m. THowever, the water in this bit of passage has since been captured down dip, like the Agent Blorenge streamway from Haggis Basher, and is probably a similar steeply descending vadose streamway - the 'Mystery streamway'. This will join the Beyond a choke stream somewhere downstream of the Riflemans choke, together with the stream in MS&D which is captured south in the Yellow Van area. The main MSD passage is a down-dip vadose passage graded to the Score-Gilwern Conduit at around 310 m OD.
The present Beyond a choke streamway will continue south beyond Riflemans, and may have led to a former resurgence at an elevation of c. 270 m in the Blaenavon area. The stream has since been captured into a lower level streamway which then flows beneath the Lwyd to the springs further downvalley.
Still huge potential in Draenen for lots more passage!
JohnMCooper
Member
There is more information in Chelsea Spelaeological Society Newsletter Volume 37 Number 12 December 1995 pp 133 and 134. The lost probe is described:
Graigwen
Active member
If Ogof Draenen water is to pass through limestone/dolomite from the east bank to the west bank under the surface river it must do so north of SO 26807 07277 where the surface river comes onto Devonian rocks at an altitude of almost 260m. If the Cwmyniscoy Mudstone is regarded as a completely effective aquiclude then we should ignore the Castell Coch Limestone and expect Ogof Draenen water to pass beneath the surface river north of SO 26178 07989 where the surface river comes onto the Cwmyniscoy Mudstone at an altitude of about 277m. As Andy has pointed out before, "a simple straight-line projection of the Beyond a Choke streamway... passes exactly through Pontnewynydd Rising!". This would imply passing beneath the river at about SO 25659 08293 where the surface is at an altitude of about 290m, the surface rock is Gilwern Oolite but the Beyond a Choke stream would be significantly lower, presumably in the Lower Clydach Valley Formation.
As water at Rifleman's Chamber is at about 260m this poses no problem as far as altitude is concerned. If you believe water from Big Country and MSD flow in the Mystery Streamway to join the Beyond a Choke stream near Rifleman's Chamber similarly there is no altitude problem and the Mystery Streamway has little option other than to be a "...steeply descending vadose streamway".
As water at Rifleman's Chamber is at about 260m this poses no problem as far as altitude is concerned. If you believe water from Big Country and MSD flow in the Mystery Streamway to join the Beyond a Choke stream near Rifleman's Chamber similarly there is no altitude problem and the Mystery Streamway has little option other than to be a "...steeply descending vadose streamway".
Graigwen
Active member
Graigwen said:
On the south side of the road leading to the Foxhunter car park, for about 400m from the junction with the Abergavenny Road, the land belongs to Torfaen Council who acquired it from the Coal Authority. Beyond that the land appears to be unregistered.
On the north side of the road, including the borehole site, the collapse feature to the east of it, Foxhunters car park and the land covered with old mine waste up towards Keepers Pond car park. the land seems to be unregistered but I guess the local council is likely to have an interest as well. The gliding clubs land does come fairly close to the east end of Keepers Pond but at Foxhunter's car park it lies east of the path going north/south and north of the path going to the summit of the Blorenge.
Martin Laverty
Member
The PDCMG having been notably quiet on this topic, their Secretary has now submitted a report to their forthcoming General meeting on 15th October (available via http://pdcmg.org.uk/minsmenu.htm ) saying of the rumours of further entrances that she "can report no further facts at this time". However, she also reports the "unilateral enlargement of the Last Sandwich U-bend and exit squeeze...a piece of passage that while without doubt had been an obstacle, had already been passed by many larger chested gentlemen"
This meeting (postponed from June) is the one where the (postponed) bi-annual elections are to take place - and the Secretary is not making herself available for re-election: an opportunity for some new ideas?
This meeting (postponed from June) is the one where the (postponed) bi-annual elections are to take place - and the Secretary is not making herself available for re-election: an opportunity for some new ideas?
Interesting to note that in her final report the retiring PDCMG Secretary states that she has been in office for "over six years". Well, I can only assume that she must have been enjoying herself so much that she has completely lost track of the passage of time! She was first elected in July 2009, hence making it a little over eight years that she has been at the head of this wretched organisation. On a personal level, I would like to wish Fleur well and I am certain she will have a far happier time caving up in Yorkshire than she has had down here in South Wales over the last few years. I have never for a moment doubted her deep rooted love for Ogof Draenen (my only issues have been with its warped and misguided application) and I genuinely do hope she will be able to find the time to enjoy its delights on many future occasions (via the original entrance of course!).
So, in the final analysis, is the PDCMG in a stronger or weaker position than it was back in 2009? I will leave this for others to decide but it is worth reminding ourselves that the cornerstone of the PDCMG's access policy has always been unyielding adherence to the totally unrealistic, completely unenforceable ideal of Ogof Draenen being a single entrance system. As anyone with open eyes can see, this is now totally dead in the water and the sooner the remaining hardliners accept this, the better it will be for all concerned. Whilst not wishing to add to the speculation regarding how many entrances may or may not now exist, I can say two things for certain: the figure is greater than one and there are most definitely more entrances open today than there were in July 2009.
So, in the final analysis, is the PDCMG in a stronger or weaker position than it was back in 2009? I will leave this for others to decide but it is worth reminding ourselves that the cornerstone of the PDCMG's access policy has always been unyielding adherence to the totally unrealistic, completely unenforceable ideal of Ogof Draenen being a single entrance system. As anyone with open eyes can see, this is now totally dead in the water and the sooner the remaining hardliners accept this, the better it will be for all concerned. Whilst not wishing to add to the speculation regarding how many entrances may or may not now exist, I can say two things for certain: the figure is greater than one and there are most definitely more entrances open today than there were in July 2009.
OK, for Ian's benefit (and anyone else who might, quite possibly understandably, be somewhat out of synch with the precise chronology of events):
Drws Cefn was connected to Ogof Draenen in August 2009 to give the third entrance into the system, less than two months after the last change of PDCMG Secretary.
As to precisely how many entrances might exist today, that is indeed a matter of speculation which, as I have already said, I have no desire to add to at the present time.
Drws Cefn was connected to Ogof Draenen in August 2009 to give the third entrance into the system, less than two months after the last change of PDCMG Secretary.
As to precisely how many entrances might exist today, that is indeed a matter of speculation which, as I have already said, I have no desire to add to at the present time.
cavemanmike
Well-known member
If i guess the correct amount of entrance's
Can I have a blue peter badge.
Popcorn time
Can I have a blue peter badge.
Popcorn time
Martin Laverty said:
It would indeed be nice to think that now might be the time for a concerted effort to be made towards a more viable solution to the question of further entrances than has previously been the case (simply fill them in!), particularly with the change in both Secretary and Chairman. However, having witnessed the vagaries of the PDCMG's electoral system at first hand, I fear such progress may be far more difficult to achieve than at first appears. For example, John Stevens (by far the best qualified man for the job by whatever yardstick you might care to use) has yet to be successful in his quest to be elected as Survey Officer, despite standing on three previous occasions. His last two defeats have been by relatively narrow margins (7-6 and 7-5, I think) and as these were a marked improvement upon his previous result (lost 14-0!), I suppose you could sway on the side of optimism and say things are at least heading in the right direction.
Any volunteers anyone?!
