Maen llia is directly aligned, along with other nearby markers, with three of the four lunar standstills; major north set, major south rise, minor north set. The minor south set is referenced by the same markers.
This is the major south rising moon, june 11th 2025.
Plan of the “Triangle”, in feet. The triangle is defined by the North West corners of the three stones.
This the same “Garsalian” triangle I have been investigating at Maen Llia. These sizes are the same as found there at Rhyd Uchaf cairn, and they also define the relationship between the mid point of the sarsen ring at Stonehenge and it’s bluestone horseshoe.
Another alignment. Apex stone, Pillar stone, Bwlch y Cerrig Duon barrow, and beyond, over the ridge, Bwlch y Cerrig Duon cist (East)
Probably the most telling alignment of all; Corner stone, Apex stone, Maen Mawr, Cerrig Duon stone circle.
The swathe cut through the reeds is a modern addition.
Corner stone, Pillar stone, Maen Leuci. Another fine alignment.
Pillar stone, Corner stone, Bannau Brycheiniog. Quite an alignment.
Pillar stone, looking towards the Apex stone.
The Pillar stone. It’s a big block about 2 feet tall with flat parallel ends, pointing about 210 degrees South West.
The corner stone from above, pointing about 150 degrees South East. The Northern edge has been shaped to fit the angle of the triangle.
The corner stone. This sits directly North of the apex stone, about 50 feet away. The top left portion looks like it may been broken off at some point. There is no sign of it now.
The apex stone. It’s an isosceles triangle, with proportions to match the main triangle. Looking South.
This is the “Triangle”. It’s a right angled triangle, with a 3d triangular stone as it’s apex. All the sides are in alignment with other monuments within the valley.
Looking South.
There is a suspected stone circle nearby but I was unable to find it.
Westernmost cairn, looking South, towards Cribarth.
The Westernmost cairn, now a shelter. Looking North towards Moel Feity.
The other overgrown cairn, looking West towards the summit cairn.
Eastermost cairn, looking East, towards the Brecon Beacons.
Eastermost cairn, looking East, towards the Brecon Beacons.
This is an A1 fibreboard cut out to match the Llia valley geometry. As can be seen its a very good match for this stone.
This stone can be found not far from Maen Llia. It is a 3 dimensional representation of the same triangle that defines the layout of Maen Llia, the Henge and Rhyd Uchaf cairn.
The North/South alignment, looking up the Tawe valley.
These are the Compass stones. A group of sizeable boulders that sit about 300 feet from Cerrig Duon stone circle.
I call them the Compass stones because bearings taken from between the high points on each stone correspond to the Cardinal points.
Summer solstice sunrise 2011. The same sunrise at the time of the stone’s construction would have been further to the left, and neatly framed by the opposing leans of the two stones.
Early April sunrise, when the shadow reaches Datum stone 1 as here. This is also the time of year when the sunset shadow first enters the stream for a drink!
Early April sunrise shadow. At this time of year the shadows cast by Fan Llia and Maen Llia meet at Datum stone 1, as indicated by this alignment megalithic.co.uk/modules.php?op=modload&name=a312&file=index&do=showpic&pid=209954.
When viewed from this direction fan Llia’s shadow crawls down the eastern flank of Fan Nedd at a snails pace (the hill beyond the shadow here) towards Datum 1. When the shadow meets the flatter level of the platform it disappears in seconds, leaving the full shadow of Maen Llia in its wake, as though it had appeared out of thin air.
This is an optical illusion that has to be seen to be believed.
Field report from “Archaeology in Wales, 1969”. Mr W E Griffiths discovered the Henge monument during a field walking trip for the RCAMW. The only other local monuments known before this were Maen Llia and Rhyd Uchaf cairn.
The three of them form a precise isosceles triangle.
Maps from 1804 and 1885. The road that runs by Maen Llia (Llech Llai on the older map) is absent on the 1804 map. It is almost certainly a toll road built around 1840 or so. There must have been a track there before then to connect the now abandoned Llechllia farm, which has no inroads on the 1804 map.
I suspect this track was originally ancient for a few reasons, but mainly because there are several significant stones on its wide verges.
The Datum stone triangular set up with the Maen Llia/henge/cairn/working platform isosceles triangle superimposed.
All these are visible on Google Earth but you may need to toggle between the different dates to find them.
The triangular arrangement of the Datum stones. The right angle formed at Datum 1 by the N/S and E/W lines is true to the cardinals at an accuracy that’s less than 2 minutes of a degree. Put another way it’s better than I could measure it and better than the accuracy assigned to the Great Pyramid of Gizah.
Datum 3 looking East, after I had pulled back the turf around the base and found no signs of packing stones or tooling.
This is the image that really made me realise that Datum 3 was possibly a genuine part of an example of prehistoric surveying and setting out.
I pulled back the thick moss on Datum 3’s North West side and revealed a flattish face that pointed at Datum stone 2. This then linked all 3 Datum stones into 1 coherent plan.
A curious observation of Datum 3 is that, although datum 3 is much flatter on its top when viewed side on, when viewed along the E/W axis the profile of Datum 3 matches the top of Maen Llia to some degree.
Another example of the artistry I have come to find in these monuments.
Datum 3 to Datum 1 close up of alignment, looking along the precise East to West line. The right hand base of Datum 3; the Southernmost corner of Maen Llia and the centre line base of Datum 1 lie along this E/W line and they also share the same level.
This could well be surviving evidence of prehistoric surveying and setting out of a baseline.
A closer view of the alignment to Maen Llia from Datum 3.
The third and final Datum stone in the Llia valley set up. This is the view looking precisely true West towards Maen Llia and Datum stone 1.
The stone here is in its original overgrown state before I pulled back the turf to see what was underneath.
I believe this may be a natural stone in its natural state, untouched in any way, with no discernible signs of packing or tooling, but used as possibly the original Datum stone that the other stones are aligned with. It’s position would seem to be too coincidental to be an accident.
Datum stone 2 from the East, showing the platform it sits upon.
