CHANTOIR DES FAGNOULES
One of the most exciting Belgian explorations of the past years...
and the discovery
In the Spring
of 2002 we started digging in this interesting sinkhole near Awagne
(Dinant). The entrance was totally blocked by debris and mud,
but after a couple of days of work, we had cleared this and we could
see a very narrow (only 10 centimetres wide) fissure that exhaled a
fresh breeze of air. Because the average Avalon-caver doesn’t
stop for this kind of “small problem” we soon attacked with all heavy
stuff we dispose off. The fissure was progressively made wide enough
(50 cm). However after having progressed 3 metres horizontally, the
fissure, still only 10 cm wide, became vertical. Despite this
complication we continued and turned the narrow crack into an artificial
pity of 4 metres deep. Only 5 weekends later, we made a break-through
into a chamber. Big piles of unstable boulders were carefully
avoided and that same day, we discovered a big new cave. Highlights
were a big room and an active streamway. This river was
most surprising: it was a real “collector” (main drain) despite the
fact that we were only at a depth of -30 m.
Click here for a “live” report of the big breakthrough on April 13th,
2002 (in Dutch)
The next day,
another team continued the exploration. Downstream they were soon
stopped by a sump. But upstream, the cave offered them a lot of caving
pleasure. They explored a few hundreds of metres of galleries, mostly
active (with a pretty river) and they found a second big room in which
a new and deep sump could be seen.
In only two
days time, we explored +/- 500 m. of galleries.
Click here for a “live” report of the big breakthrough on April 28th,
In the following
months we dug at many other places in the cave, without however discovering
“the” big continuation. We surveyed the cave entirely and
reached nearly 800 metres of total length which is not bad at all for
a Belgian cave. But it became clear that the only way on was through
the sumps. The cave was still 3 km away from the supposed resurgence
and 135m higher. We performed a fluoresceine dye test and proved
the relation between the cave and the resurgence.
May 2002: the
Lucienne Golenvaux, the most famous Belgian female cave diver ever,
dived the final sump in May 2002. The expectations were low, because
the sump was very narrow and we had tried in vain (even with a mini
underwater video camera) to penetrate it. But, Lucienne disappeared
into the muddy water without any hesitation and stayed away for quite
a while. But when she re-surfaced, we could see the disappointment
in her eyes. At first it went well, the sump was narrow, but not
too narrow and descended regularly keeping the same section. Then, after
7 metres, she hit an obstacle which she believed to be a pile of boulders.
Yet the roof of the sump went up again, however she could not get through.
That day, Lucienne also dived in another (upstream) sump, but
there she was also stopped by a passage that was much too narrow.
tries to shunt the final sump
Since the sump
wasn’t diveable at all, our only option was a serious attempt to “eliminate”
it. During many weekends we worked in the sump. This was very difficult
work, we had to lay down in the deep water, with a heavy 220 volt hammer
drill in our hands. After a while we already realized that we had started
something that would take many months of work, without any guarantee
for success. After all we didn’t even known the real length of the sump!
We considered other possibilities, such as pumping the sump dry.
But the depth of the cave (-35m) and the regular and high flow rate
of the river (8 litres/second) made this undertaking also quite impossible.
So, the only thing that we could think of, was to have a diver investigate
the other sumps in the cave…
second dive, upstream
Michel Pauwels dived in the most upstream sump, situated in “Salle Goelasnuf”.
It is a double sump, in two parallel rifts (about 70 cm wide and 4 m
long). Michel went down 3,3 metres where the passage become horizontal.
Unfortunately it was too low to continue.
That same day,
Michel took a look at the downstream sump in which we were still working.
He felt that a “second opinion” was necessary and expressed the desire
to dive again this sump, in which Lucienne had failed to find the way
third dive... sensation: the downstream sump is passed!
”Coup de théatre:” exactly one year after Lucienne Golenvaux,
Michel dives in the narrow sump. After 7 metres he meets the same restriction
that had stopped her. But after having cleared some mud and gravel,
and after three (!) attempts, he manages to pass a technically difficult
narrow slot. Five metres further he surfaces on the other side of the
sump, and meets a second shorter sump that he also passes!
A bigger gallery (two by two metres) goes on, in which he walks for
about 30 metres. The gallery continues, but Michel prefers to come back
later for a detailed exploration. Everybody is very happy,
and even if we, non-divers, might never see what’s behind the sump,
we sincerely hope that next time Michel will explore many hundreds of
metres of new cave passage.
Click here for a “live” report of this sensational dive on June 29th,
2003 (in Dutch)
2003: fourth dive... a big continuation is found
During several months we are dreaming of those virgin galleries behind
the sump. Could there be a big streamway, continuing over more
then 2 kilometres towards the resurgence? But we know that we
should better not expect too much, too soon. It is more likely
that a new sump will quickly block the way onwards.
Sunday 30/11. An Avalon-team, assisted by Lucienne Golenvaux ,
carries 8 kitbags of equipment to the sump. This time Michel Pauwels
will not dive alone, he has brought his friend Jacques Petit who is
also an expert when it comes to dive in narrow sumps.
They both have two 6 litre bottles. Michel first dives the sump
alone, and puts a solid rope through it.
For 15 minutes
we can hear him hammering a spit into the rock (the sound is being transmitted
through the rock), then he fixes the rope and returns. Meanwhile
Jacques has prepared all of his gear as well and with a 10 minute interval
they both disappear into the sump. Michel goes head first this time,
but not without difficulties. The entrance of the sumps is narrow and
it takes at least two minutes before his legs and boots finally disappear
under water! Ten minutes later; bubbles stop arriving at
our side of the sump: they must both be through. For us
a long wait starts, we keep busy and warm with some digging work in
another part of the cave. When we have finished this, we return
to the sump: still nobody. So we just sit and chat (quite easy
with Lucienne in the party!).
and a half hours later, we suddenly hear bubbles again. Soon we
see the familiar yellow glow of halogen torches in muddy water, and
then Jacques surfaces. He is really excited and all smiling, and
tells us what they have found. A third sump, which they could
by-pass by another gallery. A few inlets too, but the most exciting
discovery was a big fossil gallery, sometimes up to 10 metres wide, with
decorations, helectites and gour pools. Through deep holes in
the floor they could see the river. Finally the gallery was blocked
by a boulder collapse, but they were able to descent between the boulders
and to reach a lower level. There a spectacular 8 metre high waterfall
crashes down, it is probably the main river again. The water
disappears a bit further in a fourth sump. A narrow one, but nevertheless
it will be one of their objectives when they come to dive again (within
two weeks). They estimate to have explored about 200 metres
in length. Several possibilities and climbs remain unexplored.
half an hour later, he has surveyed the two sumps, quite difficult with
zero visibility. He also tells us that he has made many photos while
exploring behind the sump, so within a couple of weeks I hope to post
a few of them here on the website.
we are very happy with the results, and so are the two divers. The caves
reaches +/- 1000 metres in length now. But for us, non-divers,
we can only dream of the cave behind the sump, and hope that one day
we’ll find a way to get there. Other sinkholes are known downstream,
but all situated in a private forest. We hope to start negotiating on
with the owner soon.
2003: fifth dive... survey job
One of the divers had a serious cold and so they decided not to continue
the exploration behind the sump. Nevertheless, Michel did dive,
just to do a few hours of surveywork of the gallery that comes immediately
after the sump. Important survey work for us, because we are
working on a "cunning" plan (like Baldrick?) that will - if all works out
well - permit us to pass the sump... dry! No big demolition
works this time... just some pure hydraulics.
16 February 2004: 7 Avalon members
go through the sump... dry!
Today we finally passed the sump! The whole gang
(7 people strong!) went through in groups of 2 to take a quick look
of the new part that had been discovered by cave-divers Jacques en Michel
a few months ago.
It was fantastic. It is really so big, one would say a "French cave":
rooms up to 10 metres wide, interconnected by big galleries of 3 to
4 metres wide. And it goes on and on and on, over several hundreds
of metres in a nearly straight line. Some nice formations and
beautiful virgin mud floors can be admired on the way. The biggest
thrill is the 6 meter high waterfall, that can be reached by going down
a fantastic fossil phreatic tube (2 metres in diameter). You can hear
the waterfall roar over a long distance, as it tumbles down in a big
and deep pool of water. Finally the river disappears into a black sump.
the diver's estimation of 200 m in total length is way underestimated,
I would say there is at least 500 m! Time being, we will
suspend further explorations until the dry season. We have proven our
And so, HOW did we do it, going dry though a 20 metre long DOWNSTREAM
sump in which +/- 50 cubic metres of water per hour flows in?
Pumping the sump dry was impossible, because a) downstream sump b) narrow
sump and c) too much water. A deadly combination.
In very short: the river has been dammed upstream (see
photo right) and is then diverted into a flexible tube of 15
cm of diameter. The tube runs for 110 metres in length (!) and even
passes the 20 metre long sump (thank you, dear divers!) and finally
ends way behind the sump. Since the river no longer flows through
the sump itself, but through the tube, all we have to do is pump the
water out of the sump and go through it!
photo left shows the sump and the big red tube in which the river flows
(15 litres/second). The grey tubes are used for pumping the sump
dry. Simple comme bonjour. And exciting too, isn't
But, this project that started as a crazy idea of mine, has occupied
our club for many, many weekends now, and believe me: Avalon at full
speed, is like a locomotive running on nitro-methane. We have dragged
and carried hundreds of kilos of equipment into the cave, we have invented
and tried out one solution after the other in order to cope with the
many technical problems that we met. But we did it!
And as promised, you will find very soon on these pages a more detailed
description of our unique project.
May 2004: a new sump passed and many new discoveries
the weekend of 8 and 9 May, we planned to pump dry the "Ex-Terminal"
sump again, in order to assist the divers in their attempt to dive
the new downstream sump at the end of "Réseau Jacques &
Michel". But Saturday, the river was in flood and both divers
had to go on without us. Yet their expedition was successful,
because Michel managed to dive that new and narrow sump? He surfaced
after 10 meters, had to follow a low "duck" ("voûte-mouillante") for
as much as 20 m., and then walked for about 30 m. in the river
again. Then he was stopped by... yes it's getting boring... a new
sump. This sump looks very diveable. So, a success, 60 m of
progression and good perspectives.
Sunday it was a lot dryer so we managed to pump the
sump. Behind it, we started surveying and totalled several hundreds
of meters of survey, which is only a fraction of what is really
there to survey and to explore still. Meanwhile, I made a lot of
pictures so everyone can see for himself what it is all about.
A few weeks later, 20/21/23 May, we went there for
three days in a row. Dry weather, so we "pumped the sump" again.
Exciting and exhausting work it was. Once empty, the sump refills
and the passage is closed off again after only 15 minutes, because
of a water inlet somewhere in the sump itself. On one moment,
the pump broke down for half an hour, while 3 of our members where
behind the sump!
But we surveyed again, and we also discovered at least 100 m of new
passages. The most beautiful part was a long and spectacular river
part, in fact the active lower level which ends at the top of the
waterfall. Beautiful passage!
After this long weekend, the survey figure of the
cave has reached the 1100 m mark. But there remains at least another
400 m to survey, so we can safely assume that the cave totals 1,5 km
in length. So we can add the Fagnoules to our list of
"major" discoveries. And it isn't finished yet there, believe me!
At the end of the cave, we are now at -55 m while the resurgence is
Stay tuned, for more hot news about one
of the most exciting explorations of the moment.
Incomplete Survey ( screenprint)