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Système Weron-Dellieux - Mont (No. 25)


Province: NAMUR
Locality: Mont-sur-Meuse
Coordinates: Trou Weron: X=188,465   Y=116,108   Z=206,6m
                    Chantoir Dellieux:  X=188,210  Y=116,054  Z=202,2m
Map: 53/4

The access is the same as for Trou de l'Eglise; but (coming from the river Meuse) turn left on the crossing just after the church and take right after 50 m.  Both caves are at the right of the road, about 75 m away behind the prairies.  They are both large sinkholes. The Chantoir Dellieux is located behind the garden of the last house.   It is situated on private land and you have to cross the prairie to reach it.  Trou Weron can be reached via a narrow path that starts between the prairies, about 200 m further on that same road.

Trou Weron was discovered and dug open in 1938-39 by Dr. Cardeyn and explored to the bottom (-106m) by Lecomte, Cosyns and others.  Between 1960-1970 the CRS, a local club, scaled some chimneys near the bottom.  In 1989 the SC de Belgique (SCB) explored some new galleries in the "Réseau du Ruisseau", also near the bottom of the cave.  At that time the cave totals about 600 m of galleries. But for the big discoveries one has to wait until the Nineties...
In 1993 a local caver "Bibiche" and SC Avalon start a dig at -65m and discover the "Réseau Noir", almost 300 m long.  In 1995 SC Avalon nearly doubles the cave by finding the "Réseau Nord", 567m long.  Freeclimbing a 13 m pitch in R?eau de la Topo Foutue

The sinkhole of Chantoir Dellieux had been the scene of many a dig in the '50ties and '80ties (both by SCB).  In 1992 "Bibiche" and some SCB-members finally got through and the Dellieux now has been explored over 1 kilometre and is 96 m deep.   

In 1995 after a  lot of work, SC Avalon makes a junction between the two caves, thus creating one of the biggest cave systems in the country.  Finally, in 1997, SC Avalon finds a big continuation in Chantoir Dellieux; the Réseau de la topo Foutue, 615m long.  At the end of 1997, the cave systems totals over 3600m of galleries. 

Trou Weron is still a "free" cave, not gated.  Chantoir Dellieux is on private land, and is situated nearly in the backyard of the landowner's house.

Length: 3600m,  Depth: -110 m

Unfortunately it is not possible to give a detailed or useful description because of the extremely complex nature of the cave.  Indeed, the survey of the cave looks like a tray of spaghetti!  There are dozens of crossings and junctions, and sometimes as much as 7 superposing levels  So, only a very brief description of the through-trip is given here (which is insufficient to actually undertake the trip, you will have to study the publications and surveys; or find yourself a guide!).Passage des kits, a 4 m long squeeze

Through-trip Weron - Dellieux:  go down the Weron until you are at the end of the "Banquettes Horizontales" at -65m.  Empty a temporary sump that closes off the access of the Réseau Noir.  Try to get through one of the most difficult squeezes, the "Ventilateur".  At the end of the "Galerie du Far West", pass another difficult squeeze ("Klotepassage").  You reach a collapse area, follow some scotchlites that lead you to "The Danger Zone" where the junction with Chantoir Dellieux begins.  The junction, 7 m long, is one long squeeze. After this passage, two more squeezes and a free climb down some chimneys, you reach the big room of the "Système Z".  Down another squeeze, you are in the Dellieux now.  Follow the "Galerie Zéphyr" downstream.  Half way, climb up a 10 m high chimney at the left.  You'll reach a complex crossing, "Carrefour des Petits Jus" where you must take a meander that goes up (very narrow): "le Beau Meandre".  Halfway the meander, take right (if you continue, you'll arrive in "Réseau de la Topo Foutue", very big and complex).  Climb up a series of narrow and slippery pitches; the "Chicanes".  You'll arrive at the foot of a 6 m pitch,  and another 4 m pitch. Free-climb them both.  Then it gets very complex... at the head of the P4, keep left.  Then climb up a wide and steep gallery (Escalier Presidentiel).  Climb through a hole in the ceiling.  Again, a series of small rooms, connected through narrow rifts that finally lead you to a small and unstable room, just below the entrance... 


Since this through-trip is only to be done by very experienced cavers, there is no need to take a lot of gear: everything except for the Puits de la Bouteille in Trou Weron can be free climbed.  You will meet these obstacles:

P6 (Puits de la Chauve Souris)
P8 (Puits de la Bouteille): rope 10 m or ladder 5 m
R10 (in Galerie Zephyr)

This cave system is absolutely not suited for debutants.  The classic part of Trou Weron is relatively easy, but the new parts (Réseau Noir, Réseau Nord)  heading towards Chantoir Dellieux; and Chantoir Dellieux itself of course, are THE most complex and difficult in the country.  Also, there are about a dozen of severe "squeezes" of whom two are quite extreme.  So not suited for tall or heavy cavers neither. 

The through-trip takes a lot of preparation, such as studying the description and survey, and preliminary trips in Chantoir Dellieux or the far parts of Weron.   It can be done in 3 hours time, but then you must know every inch of the cave by heart.  8 hours is more realistic.  

A monography of 52 pages (Dutch language), including very detailed and large-scale surveys, was published in the review of the Flemish Caving Federation"Spelerpes Special Nr. 86, February 1999", by Paul De Bie, Yves Dubois and Richard Grebeude

This same monography, translated in French language, was also published in the review of the Walloon Caving Federation : "Regards nrs 35 & 36, 1999",

MORE INFORMATION: You can also find a long publication in the "Discoveries" part of our website, with some surveys and pictures, but this is only in Dutch.  Click here.


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