Summary of site:
Pollkerran (sometimes written Pollkeeran) is a large collapse crater (a doline) in the Carn Limestone that formed when the roof of a large cavern below became unstable and fell in. It is now a sink hole, taking the flow of a small stream. The unstable boulders from the collapse form a choke and, although digging has penetrated 15m, bedrock was not reached.
The stream sinking here emerges 2km to the north in Carrickbeg Rising Cave.
The Carn Limestone is exposed in the walls of this doline.
This is an extremely dangerous descent, not to be undertaken without considerable caving experience.