This passage tomb is large! The kerb on the southern side is very well defined. The stones from the kerb are enormous. They are all set on edge and up to 2m long.
The cairn covering the central chamber is very low. So low that the roofstone and part of the chamber and passage are exposed. It's hard to be certain, but the passage may have aligned to the northwest. The mound is 2m high and 20m in diameter.
Passage tombs are perhaps the most celebrated style of tombs, mainly due to the fantastic examples at Newgrange (County Meath), Knowth (County Meath) and Dowth (County Meath) in the Boyne Valley as well as those at Loughcrew (County Meath), which is by far the best place to experience these wonders.
The classical form of passage tomb is the cruciform style, where a long passage leads to a main chamber with 3 small chambers off, forming a cross when viewed from above. However, there are many other styles, some don't even have a passage! These other forms are with a round chamber (see Fourknocks (County Meath)), a polygonal chamber or in the form of a cross of Lorraine, which can be found at Seefin Hill (County Wicklow).
There is one form known as an undifferentiated passage tomb wherein the chamber is simply a broadening of the passage, such as at Matthewstown (County Waterford).
The passage and chamber was, once constructed, covered in a mound of earth or a stone cairn, which was in turn held in place with a kerb around its perimeter.
Perhaps what Irish passage tombs are most known for is the form of rock art more commonly called passage grave art, which can be seen in abundance along the Boyne Valley in the many cemeteries.
A kerb is a ring of stones placed around the perimeter of a burial mound or cairn. It basically serves the purpose of a retaining wall to keep the cairn or earth in place. Kerbs are usually associated with passage tombs, but do occur on court tombs and wedge tombs too.
Sometimes on passage tombs the stones can bear decoration, such as at Newgrange (County Meath).
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.