Knocknalower : Portal Tomb

CountyMayo
Grid RefF 814 345
GPSF 81391 34474 (3m)
Longitude9° 49' 10.99" W
Latitude54° 14' 43.04" N
ITM east480366
ITM north584435
Nearest TownBellmullet (11.2 Km)
OS Sheet22
UTM zone29U
UTM x449041
UTM y5761192
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Visit Notes

Sunday, 13th September 2009

There are no tracks leading into this valley, so reaching this site is a bit of a hike. I approached over the hill from Knocknalower (County Mayo) stone circle.

It looks as if every stone is still present here, but the capstone has been displaced. It is uncertain whether this monument had a double capstone or the capstone has broken in two.

The site is in a very boggy area near to the head of the valley. The views are thus restricted to being down the valley, which heads southwest. The monument is aligned roughly along the valley with its entrance facing up the valley.

The portal stones stand about 1m proud of the surrounding bog and are nicely pointed. The chamber has two stones forming either side and a single backstone. There is a nearly-full-height doorstone between the portals that now leans backwards into the chamber. One part of the capstone is in the chamber, while the other part is behind it.

Due to the monument looking so complete it is difficult to determine the purpose of the several large stones lying around the structure. These extra stones added to the fact that the capstone fills the chamber makes the site look very untidy, but this is a well preserved portal tomb.

The large rock used to form the roof of a portal tomb or kist.

Portal stones are a pair of upright stones that form the 'entrance' to a portal tomb. They are usually well matched, being of even dimensions. As well as forming this doorway they also act as the front support for the capstone and are usually taller than the stones that form the chamber.

Often there is a door stone in between them blocking off access to the chamber within.

Like this monument

Marked Sites

Random Gazetteer

A Selection of Other Portal Tombs

About Coordinates Displayed

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.

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