The cave is located some 7.5km southwest of Ballaghaderreen in the extreme northwest of Co. Roscommon and approximately 1.5km southwest of Lisacul village; NGR M 157317 289238, (50,000 map No. 32); Townland Carrownaknockaun; Altitude 94m O.D; Surveyed length 45.5m. The entrance is located part way up the southern flank of an 11m high east-west ridge just north of the point at which a small stream sinks. The cave entrance was noted by Donal Daly of the Geological Survey of Ireland some years ago and was explored and surveyed in September 2000 by the authors.

The original cave entrance was spacious - some 3m wide and 2m high but the farmer has walled in much of the opening and culverted the stream at the sink and entry is now via an easy squeeze and a 1m drop into a boulder-strewn chamber. The stream, small except following heavy rain, flows across the chamber and into a tunnel some 1m wide and 0.4m high trending almost due north. This streamway then bends to the right and has not been followed to a conclusion. The main route on is up a 1m climb into a dry passage which averages 1m x 1m for most of the remainder of the cave. The passage is floored by mud or degraded flowstone and the passage dimensions prior to infilling were probably at least 2m high and 3m wide. After 3m a low crawl is followed by roomier passage and then by a 1.5m muddy squeeze which was dug open. Beyond the squeeze the passage changes direction to run just south of east. A second even muddier excavated squeeze follows into a chamber and a cross-rift in which it is possible to stand. The passage ahead is blocked and the way to the left is sediment filled after 6m. The right hand passage leads through boulders to a rift which continues the original passage orientation of east-southeast before becoming blocked after 7m. A small stream crosses the passage at the beginning of this rift but it is not known whether it is the same stream as sinks at the entrance to the cave. The directions of almost all of the passages in the cave are controlled by one of two sets of joints as is apparent from the survey. However, the passages also seem to exhibit considerable lateral development (in the bedding?) though this part of the passage is largely infilled.

With a total surveyed length of 45.5m Pollawaddy becomes Roscommon’s longest reported cave system, just ahead of Oweynagat near Rathcroghan to the southeast (Coleman 1965, Fenwick and Parkes 1997). Roscommon has an abundance of karstic features other than caves and the fact that only two caves are known within the county may be more a reflection of the lack of investigations rather than the true situation.

The cave is located in the Oakport Limestone Formation. This formation first outcrops to the east of Lough Key and takes its name from Oakport Townland, 7km to the east of Boyle. The outcrop then runs southwestwards in a band about 1.7km wide which is bounded to the northwest by the Kilbryan Limestone Formation and to the southeast by undifferentiated Visean limestones. Dips in the area are generally less than 10 degrees and the most significant structural feature affecting the Oakport Limestone Formation is a series of major faults with northeast-southwest or east-west trends. The Oakport Limestone Formation is a massive pale grey peloidal wackestone and grainstone limestone, generally shale-free, except for minor intervals of calcilutite and dark shale.

The resurgence of the cave stream is unknown but two major springs are known in the area. Some 2.5km to the northeast there is a spring on the banks of the Lung river near Bellanaheltia Bridge, whilst some 4.5km to the northeast is the spring of Pollaneghbrick close to the Roosky River. The water from a swallowhole at Corracoggil, 1km north of Pollawaddy, has been traced to both of these springs by the Geological Survey of Ireland.

Figure 1 Plan survey of Pollawaddy Cave, Lisacul, Co. Roscommon. Surveyed by D. Drew and C. Hickey, September 2000.

References:
Coleman, J.C. 1965 The Caves of Ireland. Anvil Books Tralee.
J. Fenwick and M. Parkes 1997 ‘Oweynagat’, Rathcroghan, Co. Roscommon and associated karst features. Irish Speleology, 16, 11-14

(Source: Article reproduced with permission from Irish Speleology 17*, November 2000.)

David Drew and Caoimhe Hickey, Department of Geography, TCD