The Newgrange glacial erratics

Map of ice movement directions in and around Ireland, discerned from striae, landforms and 

glacial erratic transport evidence.

Thanks to Philip for raising this matter.  I just want to cement some of the points already raised in discussion.

The large stones found at Newgrange, in the standing stone setting, inside the passage (sidestones and roof stones) and on the outside of the mound (the kerbstones) are highly variable geologically, and there has been much discussion about how they were brought to the site.  Some archaeologists who are fond of heroic deeds and jolly narratives, think that many of them were carried up the River Boyne on skin boats.  Others think they were carried by the builders of Newgrange from sites that were deemed to be significant or sacred. 

However, those who have even a basic knowledge of geology and geomorphology have different ideas:

Quote: "It is not known with any certainty how the larger stones which form the kerb and passage and chamber of Newgrange were brought to the site. Many of these stone slabs, 550 in number, were collected from where they had been lying in the landscape. Because many of the stones were found to be weathered, it is believed they were not quarried, so there would have been a huge logistical task in finding suitable boulders dotted throughout the landscape............  Most of the kerb stones are made of grit (greywacke) or slate, and according to the archaeologists they were collected rather than quarried."

So the Newgrange story seems to be one of "stone or monolith gathering" -- not quarrying and long-distance transport -- in contrast to the Stonehenge story, in which a weird quarrying and long-distance transport hypothesis has been done to death for the best part of a century........

https://mythicalireland.com/ancient-sites/101-facts-about-newgrange/

http://thelanguageofstone.blogspot.com/2015/05/co-meath-newgrange.html

The glacial history of the Boyne valley - Newgrange area is well known.  Ice movements (and hence erratic transport routes) were very complex across several glaciations -- sometimes, local Irish Ice was dominant, flowing broadly NW >> SE, but in phases when the Irish Sea Glacier was dominant, ice flow was broadly NE >> SW.   There was an oscillating zone of confluence or conflict more or less in the position of the present coast.   Ice directions ranged across a quadrant of about 90 degrees, and maybe more. Some believe that there was at one time a northwards flow of ice from a Wicklow Hills ice dome. I doubt that -- the Wicklows are too small in scale and too far away.  Anyway,  erratics of granite, basalt, greywacke, gabbro, granidiorite, volcanic breccia, limestone, sandstone and other rock types were inevitably  moved across the Newgrange site from the NW, N or NE. At times the ice flow seems to have been more or less W >> E, and that is the direction of the most recent streamlining.

The main ice domes in Ireland, and main directions of ice movement.  Source:

https://archive.org/details/boynevalleyinice0000meeh/page/n99/mode/2up

This is a simple study (now somewhat out of date) of the glaciation of the Boyne area:

https://nanopdf.com/download/for-the-microsoft-word-version-of-this-case-study-5ad1684b600bf_pdf

Quotes from: "Glacial and fluvioglacial deposits in the Boyne Valley, Ireland" -- “All of the erratics suggest a former ice movement from NW to SE”.   Clearly not all of them.  "The Boyne Valley was influenced by ice from two sources: the north central midlands and the Irish Sea Basin ... Erratics from the Irish Sea Basin have been found as far inland as Slane” (west of Newgrange).  

More information on ice movements has come from the BRITICE-CHRONO work published in the past three years -- but nothing departs significantly from the map at the head of this post.

Some of the glacial erratics used as standing stones at Newgrange

Thanks to Philip for mentioning the work of MPP and his merry gang of quarry hunters.  This is what they said about Newgrange, last year in a book chapter:

Mike Parker Pearson, Richard Bevins, Rob Ixer, Joshua Pollard, Colin Richards & Kate Welham. Long-distance landscapes: from quarries to monument at Stonehenge. Chapter in:
MEGALITHS AND GEOLOGY. Boaventura, Mataloto & Pereira, eds. (2020). pp. 151-169

http://eprints.bournemouth.ac.uk/34408/1/Long-distance%20landscapes_megaliths_geology_portugal_2015.pdf

Extract:

Stonehenge was by no means the first megalithic monument in the British Isles to incorporate a solstice alignment. Newgrange passage tomb in Ireland was built a few centuries earlier (c. 3300-2900 BC) and the rays of the midwinter-solstice sunrise famously shine down its long entrance passage (O’Kelly, 1982; Hensey, 2015). Newgrange and its neighbouring passage tomb at Knowth incorporate rocks that are not from their immediate environs. Whilst the large kerb stones, passage stones and roof stones of greywacke come from Clogher Head, some 5 km away on the coast, other raw materials were gathered from further afield. Quartz blocks were brought from the Wicklow Mountains, some 70 km to the south, whilst granodiorite, gabbro, siltstone and granite stones probably came from up to 80 km to the north (Cooney, 2000: 136-138). The greywacke kerb stones weigh generally less than a ton, and the other rock types must have been brought in as basket-loads of cobbles and small blocks.

There was no shortage of stone materials within 5 km - 10 km to build the large, complex passage tombs of the Bend in the Boyne from local materials, so the importation of stones from long distances is likely to have been a deliberate and symbolic act. The various types of stone, especially quartz, may well have had a significance and colour that the builders sought. They may also have embodied a sense of place from their different origins, literally and metaphorically constructing the tombs out of the substance of far-off domains brought together into a single home for the ancestors whose cremated remains were placed inside.

I find this extraordinary and irresponsible.  Parker Pearson and his colleagues knew, when they wrote this, that the Boyne Valley has been heavily glaciated, and that there are erratics, drumlins, meltwater channels, eskers, glacial and fluvioglacial deposits in abundance across the landscape.  And yet they cannot bring themselves to even consider the possibility that the large weathered and abraded stones at Newgrange might be glacial erratics, and might have been gathered up from the neighbourhood. So they avoid the words "glacial" and "erratic" like the plague, and talk of the importation of stones from a long way off as "a deliberate and symbolic act".   To make matters worse, the words of the text were signed off by the geologists Rob Ixer and Richard Bevins, who were apparently unaware (as in Pembrokeshire) they they were looking at a glaciated landscape.

To summarise, the "gathered" large stones used in the passage and as kerbstones at Newgrange are most likely to have been picked up from the litter of glacial erratics scattered across the landscape.  The evidence is that they are heavily abraded and weathered -- just like the bluestones in the bluestone circle at Stonehenge. 

In continues to amaze me that MPP and the other archaeologists working at Stonehenge absolutely refuse to acknowledge that weathering crusts and abraded and faceted surfaces are characteristics of most of the bluestones. Do the Stonehenge bluestones look like quarried stones? The answer is a simple "NO"......... and that will be proved when cosmogenic dating is done on them.