Archaeoastronomy at megalithic sites

Ring-ditch KD023-038 (below) sits atop a prominent knoll on the plains of the Curragh, and lies less than 3 kilometres NE of Kildare town. This ring-ditch has a west-facing causewayed entrance which may be aligned to a place on the horizon where the sun sets at or close to the equinoxes.



I had a notion that it may also be possible to observe the sun setting at the site of St.Brigid's cathedral and round tower on the November and February cross-quarter days from this very same ring-ditch. Yesterday was the November cross-quarter day (7th. November - a day that escaped the attention of the vast majority of humanity no doubt), and what you're seeing in the series of images below is the sun setting at the site of St.Brigid's cathedral; this also means that come the next February cross-quarter day (4th. February, 2016) the sun will set in very much the same place. For those wondering what the significance of the site of St.Brigid's is, I'd recommend reading post #139 in this thread. By the way, the black dots in the amber sky are Rooks returning to their evening roost in the Curragh.









Could it be that those who constructed these ancient monuments chose the site of the monuments because it was possible to observe the sun rising and setting from/at prominent positions on the horizon, on not just one or two significant days of the year but several, i.e. at the solstices, equinoxes and cross-quarter days? My investigation of monuments in close proximity to KD023-038 (within one square kilometre) would suggest that that's a distinct possibility (see post #139 in this thread; Plate 2). My next mission is to hopefully observe the Winter solstice sun rising from the summit of Slievemaan from this same ring-ditch. I'm also very confident that from KD023-038 I will see the Summer solstice sun set between the hills of Dunmurry and Grange to the NW, at a spot known as Carrickanearla ('cathaoir/carraig an Íarla', 'the chair/rock of the Earl) that was believed to be the royal inauguration site of the kings of the Uí Failghe.

The image below was taken on Friday evening (6th. Nov.) from the centre of ring-barrow KD022-046, which appears to have its causewayed entrance aligned to the horizon where the sun sets at the November and February cross-quarter days. On the following day the sun would set 0.5° further south (one full sun width), so it looks like the alignment is very close. I also discovered that it's possible to see the Winter solstice sun setting at the site of St.Brigid's cathedral from this ring-barrow too (it's on the same solstice alignment as KD022-043, a ring-barrow discussed at length in post #139).



Ring-ditch KD023-038 can be seen in the right-hand corner of this Google Earth image, while KD022-046 lies 800 metres to the W-NW:

slowburner wrote: »

You were right to put a watermark on your photos. I would be tempted to steal them.

Here is an outside the box thought. Some of these solar movements appear to be happening on comparatively featureless horizons. If the openings in the monuments are indeed aligned on solar events, what was being used as a 'target' feature?

The large timber post that may have pre-dated the passage tomb at Fourknocks, was quite possibly a monument in itself, perhaps a form of totem pole. Timber post as monuments are only just beginning to be recognised in Mesolithic sites.
Is it possible that the monument builders on these flat plains may have erected timber posts somewhere outside the enclosure as a focus for solar alignments?

Post-hole arrangements in later Neolithic monuments (henges , causewayed enclosures) frequently echo the interior cruciform arrangement of passage tombs and this may have been sufficient architecture to see the alignments. We can only guess what was supported by the posts. There may have been timber light box equivalents in these structures. Timber, of course, would allow easier construction of more complex structures and if such structures existed, they may also have been decorated. They may have been a kind of budget version of earlier, stone built monuments. However, the possibility that there was an imposing post somewhere outside the enclosure, has a certain appeal. Finding evidence would be another matter all together.

My belief, without evidence to back it up, is that wooden posts were sited outside the barrows and ring-ditches on the Curragh to help mark specific days of the year. I created the illustration below many moons ago, which shows how this could work. In reality I think the posts should be to the left of the actual alignments shown (if that makes sense) for it to work effectively.




The possibility that there may even have been timber roofed structures within the barrows did cross my mind on many an occasion too. There's a barrow on the Curragh which appears to have a south-facing entrance, but why? The sun and moon won't ever rise or set due south. One tantalising possibility I've been mulling over is that it may have been constructed to help mark solar noon on the day of the Winter solstice. At solar noon the sun is at its highest in the sky and is also due south. Shadows cast at mid-winter are typically longer than at any other time of year (the sun is at its lowest in the sky at midday on the Winter solstice), so by using posts, one outside the causewayed entrance and another at the centre of the barrow, the shadow cast by the outer post would fall onto the post in the centre where it can then be marked. Another alternative is a wooden structure within the barrow with, as you say, something akin to a timber light box incorporated into it. It's a whacky theory I know, but Martin Brennan suggests in 'The Stones of Time' that the south-facing passage of a satellite mound at Newgrange may have helped marked solar noon on the Winter solstice, so there may have been a precedence? I was going to upload a post setting out this theory, but thought better of it, thinking you guys would consider me mad!:)

P.S. - I recall seeing a Time Team programme many years ago that was filmed at a place called Loch Migdale (or was it Loch Tay?) in Scotland, where the team excavated a henge-like monument and discovered a wooden structure at the centre of the monument. They also found a large recumbent stone just inside the causewayed entrance. A theory proposed was that the wooden posts/structure and the stone were aligned to a v-shaped notch in a mountain on the opposite side of the Loch where the sun was seen to rise/set on a certain day, so using wooden posts/structures within these monuments might not be as far fetched a theory as we think.

baaba maal wrote: »

Seriously, Bonedigger- much and all as I really, really enjoy your posts here, you should definitely be putting this together as a book. Not only is it a really well thought out theory, but you have even done the diagrams and you have knockout photos to boot!
Great stuff (and keep posting it up until you do decide to publish!!)

Thanks very much baaba - your comments are most kind!
I hope I don't sound too disingenuous but, I'm not sure that the work I've done is worthy of being published to be brutally honest.
It's really just a pet project and something that helps keep my brain ticking over.
Certainly some of my findings look more than curious, but those who've studied and explored the subject of alignments relating to ancient monuments far longer than I have will need more convincing (and certainly more evidence). I'll continue to do the research of course, and have no doubt I'll find more curiosities relating to these ancient monuments on the Curragh. How far can I take it, who knows?
If someone more learned and distinguished than I hits on the same curious alignments (whether they be deliberate or just coincidental) in the future, you can at least tell them you heard it here first!

In late November, I visited the prehistoric standing stone at Punchestown in Co.Kildare. Despite being from Kildare myself, it was the first time I set eyes on it. The monolith has been dubbed the 'Punchestown longstone', and is Ireland's tallest prehistoric standing stone (7.1 m tall). It fell in the year 1931, and when it was re-erected in 1934, a small cist was discovered at its base. The cist was found to be empty. The longstone at the centre of the henge at Forenaughts Great four kilometres northeast of Punchestown also had a cist associated with it, and along with cremated human remains, pottery, and a flint blade, a wrist-guard was also found in the cist which is a typical Beaker find. It's conceivable the Punchestown longstone and cist date to the same period, that is the EBA c. 2500 - 1800 B.C.E.

*All the images and illustrations below are my creations, except the Google Earth and Photographer's Ephemeris imagery of course.

Punchestown longstone




The presence of the cist at its base would lead one to believe that the standing stone was nothing more than a grave marker (and it's hard to argue against that), but something in my gut was telling me there may have been something else going on here. I subsequently discovered a winter solstice sunset alignment (with help from the Photographer's Ephemeris) between Punchestown longstone and Knockaulin, the ancient royal ceremonial site of Dún Ailinne. The illustration below shows the alignment from the longstone to Knockaulin with some rather curious features falling along the same alignment in between:



I had to investigate the alignment on the ground, so I visited Punchestown once again to see if Knockaulin is visible from the site of the longstone. Although the view southwest is obscured by trees today, beyond the trees is the not so insignificant hill of Mullacash. The summit of Mullacash is at a higher elevation than the longstone at Punchestown, so it was never possible to see Knockaulin from there.

This image of the Punchestown longstone was taken several days before the official winter solstice, and shows the setting sun shortly before it disappeared behind the hill of Mullacash (now obscured by the trees several hundred metres away):



Below is an image I took of the setting sun descending behind Mullacash hill on the 19th of December (standing along the alignment just downhill of the longstone). The sun set at an azimuth of 230° that evening, a mere 0.1° north of where it would 2 days later on the solstice (229.9°). What this invariably means is what you're seeing in the image below is more or less what one would see at sunset on the winter solstice. If our prehistoric ancestors were standing at the longstone just before sundown on the winter solstice, would they have seen the same thing? We must first take into account the angle of the Earth's axial tilt (obliquity of the ecliptic) which in the Late Neolithic/EBA was ~24°, but today is closer to ~23.4°. This in effect means that at winter solstice in the Neolithic/EBA the sun would have risen and set 1° further south than it does today; this 1° is equivalent to roughly two solar diameters. I believe (on rough calculation) that the full sun would have appeared to sit just above the summit of the hill briefly before setting just to the right of it.

Mullacash hill sunset two days prior to the winter solstice:




A noteworthy feature along the alignment between the longstone and Mullacash hill is a ring-barrow (KD024-008) situated 1 kilometre downslope in the townland of Swordlestown North. The alignment passes directly through the centre of the barrow. Investigations by archaeologist Seán P. Ó Ríordáin (Ó Ríordáin 1950, 273) suggested an Early Iron Age date for this barrow (and several others in its vicinity) given its similarities to barrows excavated on Carbery hill to the northwest. The ring-barrow is smothered in scrub today, and trees surrounding it make it difficult to see Mullacash, but it's feasible the winter solstice sunset was observed from here too. One tantalising possibility is that this barrow may have been a focal point for the observation of both the winter solstice sunset and the summer solstice sunrise. Although a kilometre uphill from the ring-barrow, the longstone's profile may have been visible above the horizon (hedgerows and trees along the road verges block any view now) marking where the sun would rise on the morning of the summer solstice. This will need further investigation next summer.

Swordlestown North Ring-barrow:



Summer solstice sunrise alignment from Swordlestown North ring-barrow to Punchestown longstone:




Mullacash hill is 4 kilometres southwest of the Punchestown longstone, so I took a trip up there to see if it was possible to view Knockaulin hill from there. The solstice sunset alignment passes over the hill some 250 metres north of the summit, so I needed to be somewhere close to the alignment lower down its slope. I first sought permission from a local farmer to walk onto his land where the alignment passed through. Using a handheld GPS device, I found a spot along the alignment where I hoped it would be possible to see Knockaulin, but unfortunately the view SW was obscured by trees. Moving 80 metres south of the alignment (and closer to the summit), I saw the unmistakable profile of Knockaulin on the far horizon - bingo! I took the images below 6 days before the solstice. On this evening the sun would set at an azimuth of 230.2°, 0.3° further north than it would at the solstice - this would amount to about 3/5 of a solar diameter in the difference. Taking this into account, and the Earth's axial tilt in the Late Neolithic/EBA, by my reckoning the sun's upper limb would be seen to disappear at the summit or very close to it at the winter solstice in prehistory. Excavations carried out on Knockaulin in the 1970s revealed evidence of Neolithic and Bronze Age burial activities. Linkardstown-type pottery was recovered suggesting there may have been a burial mound at the summit, but we know that ritual activities reached a peak in the Iron Age when postholes of massive circular wooden structures were uncovered during excavation.

Mullacash hill:



Sunset on Knockaulin on the evening of the 15th December:



The sun's upper limb about to disappear north of the summit:



Before leaving Mullacash, I think it's worth mentioning that while looking at satellite imagery of the hill, I spotted some curious circular cropmarks in tillage not far from the summit. One of the cropmarks falls directly on the alignment. They could be just the underlying geology, but I think they're archaeological features, and perhaps ring-ditches or ring-barrows (the largest being approximately 50m. in diameter). They don't appear on any OSI historical maps, nor are they recorded on the NMS Historic Environment Viewer.

The circular cropmarks on Mullacash which may be unrecorded archaeological features:




The very last place to investigate along the alignment was an enclosure 600 metres from the summit of Knockaulin. This feature (KD028-036) was discovered on Cambridge University aerial photography in the 1960s, and it is believed to be a ring-ditch or barrow.



Rather than trespass on land and take the shot from the site of the ring-ditch/barrow, I took the image below from the road some 300 metres further back on the same alignment.
Winter solstice sunset on Knockaulin (3:26 p.m., 21 December, 2016):



Is the Punchestown longstone to Knockaulin winter solstice sunset alignment just a random orientation?

My last post here (#174) showed the Spring Equinox sunset from the west-facing entrance of a ring-barrow on the Curragh. The sun set behind a hill known as Knocknagalliagh (Cnoc na gCailleach). I was curious if there were any other archaeological features falling along this Equinox alignment beyond Knocknagalliagh. I didn't have to look far! Just over the hill, on its lower slopes I spotted a circular crop mark in a field. I checked the SMR database and the Historic Environment Viewer, but there was no record of any archaeological feature at that particular site. It needed further investigation, so I paid a visit in September of 2017.






Anyway, to cut a long story short, this circular feature has since been recorded on the SMR database, and is classified as an Enclosure (KD022-122----). The record can be viewed on the Historic Environment Viewer here:

http://webgis.archaeology.ie/historicenvironment/


When at the site in September last, I noticed a curious looking hill on the northwest horizon through some very large trees. I knew this hill very well having visited it several times over the years. It was Croghan hill in Co. Offaly:


https://en.wikipedia.org/wiki/Croghan_Hill





Its position on the northwest horizon got me very excited indeed! There was a distinct possibility that the setting sun at summer solstice would descend behind Croghan hill itself when watching on from this enclosure. Well, on the evening of the 18th. June (Monday), I witnessed the following:







The sun (on the 18th. June) is setting on the local horizon at an azimuth of 313°, and on the solstice (21st. June) it will set at an azimuth of 313.1°. This 0.1° difference is miniscule and invariably means what you're seeing in the above images is what one would see on the actual solstice. Due to the shift in the earth's axial tilt over the millennia, it's most likely the sun would have set at least one solar disc in diameter further north (over to the right of the summit) in prehistory than it does today. I think this would have looked even more impressive!

I read recently that when on the Hill of Uisneach on the morning of the Winter solstice, the sun will rise up from behind Croghan hill. Uisneach we know was an extremely important sacred site in prehistory, but was this newly discovered enclosure a place of great sacredness too?!!

In a follow-on from post #176 above, I hope to outline the significance of the sunset I captured on the evening of the summer solstice when I witnessed the sun descend behind Dunmurry hill from the Curragh plains in Co. Kildare.
Ring-barrow KD028-074 is situated on the southeastern extremities of the Curragh plains. I discovered several years ago that it is possible to observe the setting sun descend behind the summit of Redhill (situated 10 kilometres away on the W-NW horizon) on the May and August cross-quarter days - these days would have coincided with the ancient festivals of Bealtaine and Lughnasadh.

A view of ring-barrow KD028-074 with the Wicklow mountains visible due east on the far horizon (note the position of the knoll in the background):




The May cross-quarter day sunset of 2017 on Redhill observed from the centre of KD028-074:




The August cross-quarter day sunset of 2015 on Redhill as observed from KD028-074:




On one of my first visits to KD028-074, I noticed Dunmurry hill on the northwest horizon (it has a telecommunications mast at its summit). The position of this hill on the NW horizon suggested to me that there may be a possibility that the summer solstice sun would descend somewhere close to this hill when watching on from KD028-074.
A view of Dunmurry hill from KD028-074 is now blocked by a very large tree, so I had to find another vantage point where I could take the images of the sunset, and a knoll 120 metres SE of KD028-074 seemed a most appropriate place to do so. The curious thing is the knoll, KD028-074 and another ring-barrow KD028-003 several hundred metres away fall along a summer solstice sunset alignment.

The orange line in the image below (from The Photographer's Ephemeris) represents a summer solstice sunset alignment:




The knoll is a most curious feature in that area; it has been quarried quite extensively at the SE-S, but there is what looks like the remnants of a barrow/ring-barrow at the top on its northern side. The image below shows what looks like an outer bank and shallow inner fosse:




On Friday evening (22nd June), I approached the top of the knoll from the east with the sun above me in the western sky:




Reaching the top of the knoll, I was met with the following sight:



The rise in the foreground just behind the sheep is the ring-barrow KD028-074. Note where the large tree is to the left of the summit of Dunmurry hill; when standing in the centre of KD028-074 you can't see Dunmurry. Standing outside the 'bank' and 'fosse' on the northern side of the knoll, I took the following images of the sun as it approached and then set behind Dunmurry (although the official solstice fell the evening before, the sun set in exactly the same place on the local horizon i.e., azimuth 313.1°):








So when standing at ring-barrow KD028-074 on the evening of the May cross-quarter day, the sun will set behind Redhill. The sun will travel slowly northwards (from left to right on the horizon) over the following month and a half reaching the summit of Dunmurry hill at summer solstice, and following several days of 'standstill' will then begin to travel back southwards where it will set behind the summit of Redhill once again on the evening of the August cross-quarter day.

Incidentally, I discovered a new monument in the course of this research. I spotted a circular feature on satellite imagery which is sited just west of the summer solstice alignment outlined above. It has been added to the SMR database as a ring-barrow (KD022-119). When standing at this ring-barrow, one can also see the sun descend behind Dunmurry hill at summer solstice. The image below was taken looking from east to west across the newly discovered ring-barrow KD022-119, as the solstice sun is about to set behind Dunmurry hill to the right:



One final intriguing observation made is that the summer solstice alignment from KD028-074 to Dunmurry hill also passes through the northwest end of a linear feature on Long hill (now the Curragh military camp) which is recorded on the OS 1838 6-inch historic map. Although marked on the map as an encampment, it has been suggested that this linear feature may have been a cursus-like monument, but alas, we shall never know for certain.

baaba maal wrote: »

Outstanding stuff- well done Hotei.

Thanks a million, baaba maal!

cfuserkildare wrote: »

Excellent work there,

Wish I had the time to do this as I cannot find any information about anyone having done this level of work at Loughcrew.
Has anyone found any more than Basic stories surrounding the Loughcrew cairns?

I would suggest getting a copy of Martin Brennan's 'The Stones of Time':

https://books.google.ie/books?id=AS7hpfq8K1YC&redir_esc=y

Is it possible that druids would have been consulted prior to the construction of a new settlement, and they might choose sites with certain alignments to bring "luck" or good fortune to the future occupants?
Like a sort of feng shui, to please the gods or the ancestors.

A big bonfire lighting up just as the sun set in that exact spot would have been quite an impressive sight alright.