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Earth Science Conservation Review

Summary Full report
Marble Arch Karst; PollnagollumFermanagh
Site number:349File Number:H13
ESCC:IC
Locality Type:Cave, Doline Status: ASSI
Grid Reference: H12783386
Google maps: 54.25338,-7.80513
County: FermanaghCouncil area:Fermanagh & Omagh District Council
Period:Quaternary
Stages:Holocene
Site Description
image: 0349a.jpg Fenced shaft, Pollthanacarra (collapsed subsidiary entrance to Pollnagollum).
Fenced shaft, Pollthanacarra (collapsed subsidiary entrance to Pollnagollum).
Description:
Caves associated with the underground course of the Owenbrean River but not directly connected to Marble Arch Cave comprise:

Pollasumera (see Key Site 348 - Pollasumera)

Polldownlong - a collapse feature associated with the Pollnagollum Fault.

Pollnagollum of the Boats - Pollthanacarra

Pollnagollum of the Boats is a large (30m x 70m) collapse doline directly overlying the underground course of the Owenbrean River and gives access to the river in Pollnagollum cave. Pollnagollum cave is a large active stream passage which has been explored for 640m upstream from the collapse doline. The cave passages are formed along a major N-S oriented fault zone, termed the Pollnagollum Fault. Intense brecciation and dolomitization are associated with this fault. Pollnagollum contains extensive calcite and clastic deposits, including excellent stalactites and flowstone canopies.
image: 0349b.jpg Pollnagollum: Main Chamber.
Pollnagollum: Main Chamber.
image: 0349c.jpg Pollnagollum: speleothems, Main Chamber.
Pollnagollum: speleothems, Main Chamber.
image: 0349d.jpg Pollnagollum: flowstone.
Pollnagollum: flowstone.
image: 0349e.jpg Pollnagollum: flowstone.
Pollnagollum: flowstone.
image: 0349f.jpg Pollnagollum: stalactites and flowstone.
Pollnagollum: stalactites and flowstone.
image: 0349g.jpg Pollnagollum: stalactite.
Pollnagollum: stalactite.
In the upstream part of the cave sandstone boulders approximately 3m by 2m by 1m (~16 tonnes) are deposited within one of the passages.

Pollthanacarra is a subsidiary entrance to Pollnagollum cave, which has collapsed. It is notable for an Ulster Museum pal‘ontological dig which recovered a large quantity of animal and human remains from scree slopes associated with the Pollthanacarra collapse.
Notes:
Pollnagollum, Pollthanacarra and Polldownlong are features of the Marble Arch Karst of the Marlbank-Cuilcagh Mountain Region. For general information on the features and systems of the Marble Arch Karst, including this one, and a reference list, see site description 'Marlbank-Cuilcagh Mountain Region; Marble Arch Karst'.
Keywords
Minerals:Calcite, Dolomite
Rocks:Breccia, Limestone
Structures:fault
Geomorph:cave, clastic sediments, doline, flowstone, speleothem, stalactite
Measurements
Length:640 mWidth:Height:
Depth:Area:  
Record type: ESCR report    
Entered by: Doughty, P.J.
Last updated:24 Dec 2003
 Enlander, I., Dempster, M. & Doughty, P., 2026. Marble Arch Karst; Pollnagollum, County Fermanagh, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=349. Accessed on 2026-11-06.

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