2013 SUI Literary Award Winner

 

The winner of the 2013 SUI Literary Award is Petie Barry who has contributed extensively to Irish caving publications throughout the year.  Petie has had a number of articles in print including

The Caves of Tipperary (Irish Speleology)

The Caves of Largy, Co Leitrim (Irish Speleology, with Al Kennedy)

Irish Depth Potential (Underground)

 

but it was the depth potential article  which caught the judges eye so congratulations and well deserved!  The article is printed below

 

 

Depth Potential

By Petie Barry

 

 

The purpose of this article is to identify where the caves with the greatest depth potential in Ireland exist, and how likely they are to be explored to their full potential. Currently in Ireland there is no cave deeper than 200m – hopefully this list will spur people on in the search for “mega-deep” caves in Ireland.

This is an armchair survey, and I make no great claims on its accuracy. Several small sites have been omitted because the details were a bit hazy, or the prospects too preposterous.

Reyfad Plateau – 220m max

Depth Potentials:

– Rattle Hole – 210m

– Murphy’s Hole – 215m

– Ivy Hole – 175m

– Reyfad (Polltullybrack) – 220m

Altitudes:

– Carrickbeg – OD 85

– Polltullbrack – OD 305

– Rattle Hole – OD 295

– Ivy Hole – OD 260

– Murphy’s Hole – OD 300

At 193m deep Reyfad is the deepest cave in the country. A huge 80m shaft drops into huge passage, and the Aghnahoo Extension, discovered in the late ‘70s, extends the cave’s depth massively, with Martyn Farr finally diving Sump 3 to -9m. Reyfad’s depth is only an estimate, a potentially dodgy one at that (caused by a lack of accurate survey data for the far end and controversy surrounding the tie-in of Polltullybrack, among other things), so no-one really can say for sure how deep it is.

What we do know however is the elevation of Carrickbeg, the rising for effectively the whole Reyfad Plateau. The highest sink above this is Polltullybrack which is also the highest point of the Reyfad System. It is 230m above Carrickbeg.

The possibilities of making a connection from Reyfad to Carrickbeg are slight. There are no easy leads left in Reyfad. Aghnahoo Extension is very remote and ends in a constricted sump. Reyfadhoo Passage is silted up. Pollnacrom sump contains David Wood’s earthly remains. The New River choke is huge and going in the wrong direction entirely. Carrickbeg is no better. After a 1km tramp upstream in fine passage the terminal Sump 3 is met. Here the rock changes from the good solid stuff to the crappy Boho stuff. The sump is unpleasantly small and bouldery and foiled Artur Kozłowski’s dogged attempts to pass it. It is not likely to go easily, or even at all.

What then of the other sinks above Carrickbeg? These have not been extensively looked at. The most promising is Rattle Hole, a 30m deep shaft ending in a drafting gravel filled fissure. This has been dug sporadically, most recently in the early 90’s but the cave edge conspired to collapse, undoing much of the digging work at the bottom and attempting to pull one of the diggers into it’s earthly embrace. Perhaps the time is ripe to have another go? The pot has the potential to drop 210m to resurgence level, and if the famously strong draft is anything to go by, potentially find a whole load of cave while you are down there.

The neighbouring caves to Rattle hole may too have potential, though I’ve not been up there personally to inspect the prospects.

Will it go?

Reyfad isn’t going deeper any time soon, and the access issue is only part of the problem. Rattle Hole is a good prospect, but the digging might be tough and required a concerted effort.

Shannon Cave System – 206m

– Shannon Pot OD: 109m

– Shannon Cave Depth: 134m (Tullyard to Terminal Sump)

– Depth of Shannon Pot: 14m

– Highest sink: Badger Pot OD: 301m

– Potential Depth of Shannon System: 206m

The water sinking on East Cuilcagh covers a great distance horizontally on its journey to Shannon Pot. Shannon Cave itself is 134m deep from Tullyard to the nadir of the terminal sump. Possibilities to make the cave deeper are limited. The sump is unpleasant and remote, making extensions here hard won. The portion between the terminal sump and Shannon Pot is also unforgiving, probably with some long sumped sections. More daunting is the fact that the stream passes through a bed of loose shaley limestone which is unlikely to be easily passed.

Shannon Pot probably has been dived as much as it ever will be, with the divers entering a desperately unstable “washing machine” of boulders 14m down. The sink end is equally hopeless. The friable rock of East Cuilcagh is unlikely to sustain a passable passage westward to Shannon.

Will it go?

Probably not. Though it may happen that the continuation of the Shannon stream is encountered west of Shannon via a sink in the Pollboy area, potentially adding 20-30m onto Shannon’s depth if it could be connected back by diving. Also, the great unknown of Mistake Passage remains largely unpushed, heading into a vast unknown area. Watch that space.

Belmore – 220m

Hypothetical rising at Holywell (OD: 80m), several possible sinks at the 300m contour on the hill. Say 220m?

Most people will have caved on the northern slopes of Belmore via Coolarkan, the most notable cave on the mountain. Few however will have been along the southern slopes of Belmore where there is a great multitude of small sinks and a few unexciting caves. It is with good reason that few people go here – the sinks are tiny and the few caves short and unpleasant. This is down to geology. The southern slopes of the hill are heavily faulted and fractured, the limestone not being of the sort capable of holding its own weight. Also, the long shape of the mountain means that catchment is small and fails to form streams that could create sinks of consequence.

The rising for all the water sinking on the hill is presumed to be Holywell – a curious rising just north of Belcoo that’s apparently in sandstone. I’m guessing that all the Belmore water sinks down and travels west in some kind of main drain, though given the poor quality of the limestone it would probably be like Shannon on steroids. In any case such a hypothetical main drain is probably inaccessible.

Will it go?

As Ian Paisley says; NEVER. NEVER. NEVER. Never.

 

Clare –

 

North-West Sliabh Elva – 270m max

– Poll na gCeim – 242m

– Faunarooska – 263m

– Pollapooka – 268m

It is potentially along the western flank of Sliabh Elva and Knockauns’ mountain where the deepest cave in Ireland will be found. Here, a line of caves from Pollapooka to Poll na gCeim all have the potential to break the 200m mark. The caves are located most dramatically overlooking Connemara and the Aran islands. The water sinking in the caves rises beneath the waves of the Atlantic Ocean only a few kilometres away. Unfortunately, at a certain depth the caves end. Both Faunarooska and Pollballyelly pinch off dramatically at about the same horizon, indicating that there is a layer of rock not very conductive to cave formation. Poll na gCeim manages to pass this by being situated on a fault, though this also makes the cave loose and bouldery. Any hope of extension in these caves depends on being able to pass this horizon. The potential is vast. Anyone who has witnessed the terminal passage of Pollbalinny will wonder what the continuation must look like. It is postulated that a huge depression at Balinny is the infilled remains of a huge ancient sink network that must have produced some massive cave passage further down in the mountain. It was this postulation that drove the Burren Crawlers to dig at Poll na gCeim. Let it drive you.

The contenders:

Poll na gCeim is considered the second deepest cave in Ireland, though like Reyfad this is an estimate, the remoteness of the far end of the cave leaving it unsurveyed. It may even be the deepest… Poll na gCeim, originally a small unassuming sink, was dug open by Colin Bunce and Brian Judd in the late 80’s and concerted diving and engineering saw six sumps passed down to the bottom of the cave. The end of the cave was last visited in 1992, a solo trip by Judd who found himself backing out of a loose boulder choke. It needs revisiting. Unfortunately, this would require sorting out the access dispute, recruiting divers, recruiting sherpas and repairing the pumps. A lot of work and high risk, given the looseness and remoteness of the lower reaches of the cave.

Further up the hillside is

Faunarooska. Oft visited by caving parties it is 97m deep, ending in pitches dropping to two sumps, both dived and neither passed. The sumps are the only way on essentially. The tight wet pitch sump is effectively a write off. The dry pitch sump may benefit from underwater digging, or investigation towards the end of a prolonged dry spell.

Further up still is

Pollapooka, a large surface shaft ending at a boulder floor. Not quite 30m deep it is a most promising site. In the late 80’s a British crew dug here for a day or two and removed enough boulders to view a canyon passage taking all the water. Unfortunately this collapsed before they could enter it. As far as I can tell this site has the greatest depth potential in Ireland. Digging could be challenging, though the rewards could equally be vast.

Will it go?

I dunno. Maybe. Whatever.

Largy – 235m

– Rooney’s Rising – OD 70m

– Deep Pot – 112m deep, OD 300m

– Pollrúnda – 66m, OD 305m

Over the past few years the Shannon Group has been doing much work in the previously neglected Sligo-Leitrim area. We have discovered that:

1. There is a huge amount of unrecorded potholes up there.

2. These potholes generally don’t go far before choking with rock; peat; dead sheep etc.

3. Every once in a while one goes deep, usually on a fault or similar.

The case in point is Deep Pot on Largy. While it is not a new discovery, the ease with which we were able to push it over the 100m depth line shows the possibilities of the area. Further diligent fieldwork is likely to identify more such pots, though the geology is unforgiving

While we haven’t actually traced a rising for the Largy potholes, a likely spot is a Rooney’s Rising, where a medium-sized stream appears in the middle of a field. It is impenetrable. 230m above this is the entrance to Deep Pot, which, assisted by a large fault, drops down 112m before ending in minuscule crawls. Slightly higher up the hill is Pollrúnda, 66m deep and ending reasonably definitively at a gravel floor. It’s entrance is 305m above the lowest rising attributed to it.

Will it go?

Nope. That limestone is almost half chert. The fact that Deep Pot went so deep at all is down to it’s being aided by the fault which provided a useful conduit for the water to eke out a cave passage. Alas, such depths are rare in cherty limestones. In any case, Deep Pot is unlikely to get any deeper in our lifetime…

Truskmore – c.200m

Close to the summit of Truskmore, Co. Sligo lie the highest caves in Ireland, the largest of which is Pollnacrioc, a standard Northern cherty rift pot, though unusually it ends in a sump. While on the face of it this would appear to be a good spot for a deep cave, sitting at an altitude of 510m or thereabouts, the cherty limestone engenders little confidence that this is the case. Additionally the sump backs up dramatically in flood, a sure sign of a constricted outflow.

The risings are unclear. In flood the cliffs beneath Truskmore sprout numerous risings at various levels of the cliff face, the lowest being situated around the 300m mark. This indicates that the lower reaches of the water’s course through the mountain are quite constricted and can back up to considerable heights.

Truskmore’s is a story repeated across much of Sligo-Leitrim – that of a great height difference between sink and rising that cannot be followed due to the inhospitable chertiness of rock. Had nature not conspired to make the north-west’s limestone so cherty we might have had an area of caves to rival that of Yorkshire, but alas, t’was not to be.

Will it go?

No.

Closing remarks

It is the opinion of the author that the caves most likely to first break the 200m depth mark in Ireland are, in no particular order…

– Rattle Hole (or nearby cave)

– Poll na gCeim

– Pollapooka

None is likely to go easy. Poll na gCeim has it’s access problems and would require a daunting amount of effort even to regain the end. Rattle hole has instability to deal with and an awkward dig. Pollapooka is a great unknown. Even if the boulder floor could be dug past there is no guarantee that the cave is passable beyond the stymying horizon. You won’t know until you start digging.