Hidden in a cliff face on the high Marlbank, Pollasumera is where the Owenbrean sinks after journeying down the plains of Cuilcagh mountain. Despite the massive entrance, set in dramatic 20 meter high cliffs, the cave regularly floods to the roof and passageways become logged with washed-in debris such as dead wood, fence posts and some more unusual items.
Beyond the great entrance the passageway continues north but soon changes west as it begins to stoop to crawling size. The river sinks and makes its way south to Marble Arch via Pollnagollum Of the Boats. A similarity shared between ‘Sumera and those grander caves can be seen in the same quality of dense and pure limestone laid down in massive beds. There are few chert bands and the solid walls are well scalloped from a millenia of bearing large torrents.
After the stream sumps there are some dry passages that continue south. Around this area the way on becomes more difficult, becoming very tight and blocked with calcite barriers. However eventually one reaches Leeds Hall, the last relatively big chamber.
There is a feeling here of the ‘route’ being constantly open to change with many once ‘obvious’ passages becoming choked up with mud and and washed-in debris. This highlights the ability of the cave to flood quite rapidly and aggressively. On my last visit signs of such recent flooding could be seen clearly, when high walls and the ceiling were still covered in a thick layer of foam that light up prettily under a caver’s lamp.
The cave survey was a highly variable one in which multiple side passage surveys of varying degrees of quality were attached to the main ‘spinal’ survey. Fortunately, a new survey has been drawn up by Petie Barry and cohorts (Barry, 2019) and is now available in Irish Speleology No. 24, with an accompanying article generously decorated with the photos on this page.
Barry, P. , 2019. Pollasumera, Co. Fermanagh, Irish Speleology, 24, 65-71.