The Exploration of Pant Mawr Pot
by Peter I. W. Harvey contents
Aubrey Glennie mentions a trip to Pant Mawr in his obituary to Platten,
but does not give a date:
Gerard Platten is perhaps
best known to post war cavers as the author and compiler of the British
Caver, but he was also an active and proficient caver, until ill
health made caving impossible. A notable example was the early
descent of Pant Mawr Pothole. The party was a large one; Gerard
was the leader and he kept the whole operation of laddering, lifelining
and exploration closely under his control. At all times in his caving
days he did much to help beginners without making things too easy. . .
Neither Gerard nor Aubrey kept diaries but Platten mentions in a note
in the British caver (vol 25 p 29) that he, in company with E. E. Roberts,
Gowring and Bill Doyle, descended during Easter 1937. It is probable
that there were several more on this trip, including Aubrey Glennie.
It appears that Jim Braithwaite, Austin Wadsworth and Hywel Murrell were
the first to descend; they visited the pot on 18th October 1936, taking
up so much gear that they had to hire a horse from a local farmer.
Both Jim and Hywel wrote up their experiences of the exploration.
Murrell wrote, I believe to Gordon Warwick, as follows:
What was, I believe, the
first organised examination of the caves in the valleys of the tributaries
of the Neath River had been started in Sept. 1936 by members of the Wessex
Cave Club. During the first visit a useful local contact had been
made with Jenkin Lloyd, an ex miner, with authiscosis (?) and then a handyman
and part time poacher, who made extensive enquiries about possible caves.
Thus we heard about Pant Mawr from a shepherd, and a party consisting
of Jim Braithwaite, Austin Wadsworth and H. Murrell visited it on Sunday
October 18th. 1936. Since no cavers had been active locally and
the shepherd, an elderly man, had never heard of anyone having gone down,
it was I believe the first exploration. There was no evidence of
anyone having been there before.
We hired a pony to carry
the ladders (of course we took far too much) and on that occasion explored
as far as we could get above the waterfall and found that the “duck”
in the first boulder choke was passable.
Our second visit was made
on Sunday Nov 15th 1936. It was a day of driving misty rain and
not only did we lose part of the party (Braithwaite, Wadsworth, Murrell,
Puch? and some helpers) but we could not for some time find the hole.
Braithwaite and Murrell went through the “duck”, passed another
roof fall but were unable to find a way through a third. We had
to return to Somerset that night and gave up when no obvious way on could
be found. We never visited the cave again. . . . .
They probably did not know the depth of the pitch so carried up more
ladder than they needed. There was nowhere round the hole to belay
the ladder to so they had to include some form of earth anchor to be driven
into the moor. At that time they were able to pass through the boulder
choke and after a few feet were stopped by a further choke. Jim
writes in ‘Caves and Caving’ Vol 1, No 3, page 97, entitled
‘Porth yr Ogof and its neighbours’: back
to the top
Pant Mawr is the high
ground to the west of the Little Neath Valley, and it is here that we
have made one of our most important finds. A sink was dicovered
on the edge of a boggy saucer-shaped area of moorland, and the hole itself
is situated in the centre of this conical depression. It has been
given the name Pwll Pant Mawr. Being two miles from the nearest
track we hired a horse to take the tackle up to it.
On descending, it was
found that a 60ft ladder climb brought us to a scree of boulders sloping
down to the streamway some 30ft below. The hole opens out into the eastern
side of a large chamber. The stream runs in a N-S direction on the
western side. Going northwards, a passage on the right leads up
to a small chamber with a sandy floor, the walls of which are beautifully
decorated with stalactite and from here another rift, with shelves of
harder rock left projecting along the sides; this leads to the foot of
a magnificent 25ft waterfall coming in on the left, a rift leads straight
on, and this, after a climb of 40ft, gives access to a low bedding chamber.
A way on was found from here back to the top of the waterfall, and from
here there was one of the most inspiring sights I have ever seen.
It is imposible to get upstream any further, as it splits into several
small feeders, all too small to permit progress.
Downstream from the main
chamber is very easy going. The chamber opens into a spacious passage.
The stream was followed for some distance before a blockage was reached
in the form of a fall from the roof. There was no way over the fall,
but we found a way through the boulders following the course of the stream,
although this necessitated total immersion. The passage resumed
its original dimensions again only to continue for a short distance to
another fall from the roof - which has not yet been passed.
Lionel Dingle and Greenwood visited the cave later on and were unable
to go any further. It was in 1939 that Dingle, during the B.S.A.
Conference in Swansea, led a party down the known part of the cave.
At the Easter meet in the Swansea Valley, beginning Friday 15th April
1949, the SWCC made its first visit to the moors east of the valley, when
a large party went up to explore Pwll Pant Mawr. This was a pothole
about a mile to the east of Pwll Byfre, with a 60 ft pitch at the bottom
of a 20ft roughly conical depression. A large party had to be assembled
in those days in order to carry all the equipment needed for the descent
of the entrance pitch. We needed about 200ft of rope to tether the
ladder, crowbars to provide an anchor, a sledge hammer to drive the crowbars
in, 150ft lifeline and 75ft of rope ladder. All this to descend
a 60ft pitch. The cave at the bottom of the pitch consisted of a
main passage, of quite large dimensions, going in a south-easterly direction,
approximately 30ft wide and 20ft high. After about 1000ft, progress
was stopped by an impressive boulder collapse. To the north of the
entrance pitch some narrow passages could be followed in the direction
of the swallet, which was not far away. back
to the top
I drilled two rawlbolt holes at the head of the pitch. This allowed
for a 50ft ladder and a lifeline, considerably reducing the weight of
tackle required for the climb. Later on, the Severn Valley Caving
Club drove a 10ft railway line into the moor on the level at the top of
the depression. As the passage of cavers increased, the path down
the side of the depression to the top of the pitch suffered considerable
erosion, which began to indicate that the solid rock I had drilled the
bolt holes in seemed to be two boulders resting on others at the top of
During these visits I introduced some fluorescein into the swallet
which was about 100 yds from the pothole. It was assumed that the
dye would resurface somewhere in the Neath Valley to the east, but although
we kept watch at the likely spots for several days we were unlucky.
I tried again the following Easter with the same result. It was
not until the following year, 1951, when we spent a fortnight in Wales,
that we had success and saw the dye coming out at all the risings in the
Neath Valley just above Pwll Ddu. It took five days to traverse
the cave. I had been using ever increasing quantities of the dye
and, for the final test, 5lb was used. I heard later that there
was nearly a religious revival at Pont Nedd Fechan on account of the river
Neath turning green every Easter.
the summer of 1953 John Alexander, with the help of David Hunt and Clive
Jones, surveyed the known parts of the cave. I was in the cave on
the 12th September with Bill Clark and Edward Aslett and we had a good
look at the boulder choke without finding a reasonable way through.
The whole place consisted of large slabs of fallen limestone interspersed
with shale, which did not look at all encouraging. Bill Little
writes in the SWCC Newsletter (No. 7, Jan.’54), summarised
The following day Clarke
went through, this time with Edward Aslett. Beyond the wet crawl
they crossed a fair sized chamber decorated with straws and some strange
stalagmites, and climbed upwards through the second choke. An Oxbow
passage on the left bypassed the next constriction, after passing some
eccentrics and a gour pool swung back into large passage again.
The stream re-appeared
in the floor and high up they passed a cross passage with curtains well
out of reach of muddy fingers, finally coming to a third choke.
Clarke and Aslett came back wet and tired but they had found the way on.
It was September 20th after a week of heavy rain that Clarke, Leyman and
I went down. We crawled into the Braithwaite/Murrell route to find only
2ins of airspace in the tightest spot. Discretion, we decided, was
a good excuse for not getting wet. We retraced our steps and climbed
over the boulders under the sagging roof and carefully searched every
cranny. A hole beneath a crumbly shaleband, whilst looking most
unnattactive, proved to lead to the shattered zone between the first and
second boulder chokes. After some adjustment, this new route looked
a lot safer and was unnaffected by the level of the water.
We pushed on down to the
third choke and scrambled up an opening behind the calcite flow on the
right. It went easily, avoiding any loose blocks. Before us
stretched a large chamber, the end of which we were unable to see (Great
Hall). We carried on, meeting the stream again. Further on,
a spout of water issued from a 6in hole in the wall (Fire Hydrant).
We carried on until everything became covered in a sticky mud, the passage
became narrower and the stream finally disappeared in a most unattractive
The main passage in Pant Mawr is quite large, 30ft wide and 20ft high
or more. The stream at the end disappears down a miserable little
crack filled with mud. I have long held a theory that the water
that enters Pant Mawr Pot originally flowed underground towards the Swansea
Valley and possibly there was a connection with Ogof Ffynnon Ddu.
Having read Dr. North’s book ‘The River Scenery at the head
of the Vale of Neath’, I wondered if the Neath Valley which, he
says, was cut down very quickly in recent geological times, captured
this water underground and changed its flow towards the Neath Valley.
It was this theory that set me wondering if the water that went to ground
into Bridge Cave, higher up the Neath Valley might actually resurge in
the Mellte Valley somewhere near Porth yr Ogof. There is no natural
law which requires an underground river to stay in its own valley.
In dry weather the Neath Valley is dry between Bridge Cave and the Pant
Mawr risings. It was this thought that prompted me to put some fluorescein
in the water flowing into Bridge Cave. In the end, my theory was
proved wrong; the fluorescein came out in the same valley in the same
risings as the stream from Pant Mawr, proving that the Bridge Cave
water stayed in the Neath Valley. In actual fact there are still
people who say that that Bridge Cave water divides underground, some staying
in the Neath and some resurging just north of Porth y Ogof. This
could possibly happen in flood conditions. When I did my test, I
saw the dyed water coming out in the Neath but omitted to see if it was
also coming out in the Mellte. I think it would be most unlikely
for an underground river to divide in this way, but it could be possible
that there are two resurgences in time of flood.
Edited by Jem Rowland back
to the top
23 March, 2009