|Boho; Pollnagollum Coolarkan||Fermanagh|
|Site Type: ||Cave|
|Site Status: ||PASSI|
|District: ||Fermanagh District Council|
|Grid Reference: ||H12214311|
|Rock Age: ||Quaternary, Carboniferous (Asbian, Holocene, Visean)|
|Rock Name: ||Dartry Limestone Formation|
|Rock Type: ||Chert, Limestone|
|Other interest: ||bedding, No Data, breakdown, cave, doline, gour pool, sinkhole, stalactite, straw|
Summary of site:
Pollnagollum Coolarkan is entered by a passage from the base of a doline (a crater formed when the roof of a large cavern became unstable and collapsed). A 12m high waterfall pours over its rim and enters a passage 5m wide, 3m high and 85m long. The stream runs along the floor of the passage, swinging from side to side; it passes through one navigable boulder choke but terminates at the next which has so far proved impenetrable. The water in the cave emerges 1.8km to the west north west, on the valley floor of the Aghanaglack River.
There is a suggestion that the cave was formed when an ice sheet that filled the Aghanaglack Valley in the late Pleistocene (the end of the last Ice Age) began to melt. The meltwater run off was concentrated at this point, first thawing the bedrock which was then subjected to concentrated weathering. There is, however, little direct evidence to support this thesis.