This souterrain is located in the centre of an unusual cashel or stone fort. The whole of the roof over the passage is missing and just one lintel remains over the small terminating chamber remains in place.
The plan of the souterrain is rather cute. It starts with a 1m long section of passage that it entered from the east. The passage then turns 90 degrees to the south and continues for 5m leading to an off-centre circular chamber that is about 1.5m in diameter. This makes it quaver-shaped.
This is an explanation of (and a bit of a disclaimer for) the coordinates I provide.
Where a GPS figure is given this is the master for all other coordinates. According to my Garmin these are quite accurate.
Where there is no GPS figure the 6 figure grid reference is master for the others. This may not be very accurate as it could have come from the OS maps and could have been read by eye. Consequently, all other cordinates are going to have inaccuracies.
The calculation of Longitude and Latitude uses an algorithm that is not 100% accurate. The long/lat figures are used as a basis for calculating the UTM & ITM coordinates. Consequently, UTM & ITM coordinates are slightly out.
UTM is a global coordinate system - Universal Transverse Mercator - that is at the core of the GPS system.
ITM is the new coordinate system - Irish Transverse Mercator - that is more accurate and more GPS friendly than the Irish Grid Reference system. This will be used on the next generation of Irish OS maps.