This site is not on the OS maps and I only learned of it via a book. The fact that it is close to a portal tomb I know very well meant I had to try to find it. The only clue I had was it's height (48cm) and the fact that it is in a field in Onagh.
After climbing to see the quartz outcrop above Onagh portal tomb I scoured the slopes below and saw, an equal distance past the portal tomb, a low lump of rock in a field so off I set.
Mission successful! The large outcrop with these markings is badly weathered and only the large cup mark would really alert you to the presence of the other markings. There are several small cup marks, one of which has two rings.
Its location, on a small promontory of land below the portal tomb pointing towards The Great Sugar Loaf, combined with its low table like shape gives the impression of an altar. The face with the carvings is nearly horizontal, sloping slightly toward The Great Sugar Loaf.
Portal tombs are what most people wrongly refer to as dolmens. They are, to me at least, the most strikingly designed of the megalithic tombs. They are called portal tombs because they have two large upright stones, usually very well matched, in front of the chamber that seem to form a doorway.
Resting upon the portal stones and the chamber a large capstone rests (sometimes there are two capstones - see Knockeen (County Waterford)), usually at an angle of around 22 degrees from the horizontal. Although these were originally incorporated into one end of a long cairn there are none left in this state today, although traces of the cairn can sometimes be seen upon the ground. The portal stones can be up to 3.5m tall, which combined with a thick capstone can produce an imposing monument over 5m tall. Capstones can reach in excess of 70 tonnes, with that of Browne's Hill (County Carlow) being estimated at over 120 tonnes.
Often betwen the portal stones there is a door slab, blocking the width of the entrance, but not always the full height. Door slabs are either half height, three quarter height or full height, describing the amount of the portal that they obstruct. All portal tombs would have had door slab, but this has often been removed to facilitate entry into the chamber.
Quite rarely the portal stones are the same height as the chamber and the characteristic slope of the capstone is created by the profile of the capstone (see Glendruid (County Dublin)).
Another trip to see that I could re-locate this stone again. Nearly.
The markings are now very badly eroded. In the direct sunlight I struggled to see anything apart from the large cup (or small basin, depending on how you think of it.)
If this stone was discovered today it would be classed as a bullaun stone, as none of the rock art is visible to the naked eye.
From Enniskerry take the Glencree Road and take the first left. Turn right at the next junction.Follow this road around for about 900m until you see the tomb on you left (80m into a field in the hedge). The rock art lies two fields beyond the tomb away from the road.
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.