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Monday, 9 May 2011

L'Ile Carn, Brittany -- wow!!

 The stone-faced facade of the whole burial mound, on the highest part of the island.  You can see the semi-circular mound which might have contained a courtyard in front of the facade.  A ceremonial / ritual feature?  We won't go there........

 Entrance to passage 1 -- very low, and a bit of a scramble on one's stomach

Entrance to passage 2 -- no public access.  But note the stepped facade.  It's
reminiscent of a stepped pyramid 

Entrance 3 -- to the double vaulted chamber.  it's quite easy to get into this one.....
Entrance 3 -- note the high quality of the dry stone walling

Just returned from a very jolly twinning visit to our twin town of Plouguin in Brittany, and our hosts were kind enough to take us, on a beautiful spring day, to the little island called L'Ile Carn, near Portsall, Ploudalmezeau (Finisterre).  It's only accessible at low tide, after a scramble across the rocks.  But it is amazing -- on the summit of the island there is a stone-built burial mound which looks from a distance as it it is a rocky knoll or a granite tor -- but it is entirely man-made.

It's one of the best Early Neolithic passage graves in Brittany, made of dry-stone walling, with megalithic lintels over the chamber entrances and over the tunnels (passages, if we want to call them passage graves) but with corbelled vaulting in 4 chambers.  Charcoal from one of the chambers is dated to c 3270 BC.  Other published dates suggest 4350 BC - 3800 BC (6350 BP - 5800 BP).

At Carn (excavated 1954) the dating upset at a stroke the views of Piggott, Daniel and many others on the dating and significance of Armorican passage tombs; at Barnenez (even more spectacular, with a sort of stepped pyramid shape and no less than 11 passages and chambers) the scale of the monument attracted a visit in September 1955 by Sir Mortimer Wheeler with Glyn and Ruth Daniel, Paul Johnstone and BBC television, and the results of radiocarbon dating confirmed the pioneering result from Carn.  The similar mound at Guennoc, though perhaps less spectacular, corroborated the dating and confirmed and extended knowledge of the distinctive architecture and the material remains from Armorican passage tombs.

What I found particularly impressive at Carn was the skill of the builders in dry-stone walling techniques, and the manner in which big slabs were used for the roofing of the passages but were then replaced by corbel vaulting techniques for the creation of the four spacious chambers.  They are incredibly impressive -- the biggest is in the central tunnel, but it is now collapsing, so no public access is allowed.  But one can crawl into the other 3 -- and each one is very spacious, with the top of the vault at least 4m above floor level.  The chamber reached via entrance 1 is a bit of a struggle, but when you get in through entrance 3 you find a double chamber, with corbelling and arching and a dividing wall which is as stable today as the day it was made, around 6,000 years ago.  There was clearly a ceremonial facade, and there might have been a sort of courtyard as well, since the front of the mound (where the finest stone walling and the entrances are located) is protected by a semi-circular embankment which might have been a stone wall originally -- now thoroughly collapsed.

 The dry-stone corbelling technique -- looking straight up at the top of one of the chambers

The interesting thing from my point of view is that this mightily impressive engineering feat depended upon stones that are all locally sourced -- from the big storm beaches that surround the island, and from the granite outcrops of which there are many.  The builders put a massive amount of effort -- and no little skill -- into their project -- but why would they want to make matters complicated by bringing in stone from somewhere else?


Flo Fflach said...

reminding me of a big chambered "tomb" somewhere in uk....or was it in ireland... and also some later constructions in menorca - talyot

BRIAN JOHN said...

Hi Maura -- you mean Newgrange? The one that has been controversially "restored"??

Hope you have slept well!

Constantinos Ragazas said...


Very impressive indeed. I am truly amazed that 6000 years ago primitive men were able to built high vaults with just dry-stone wall techniques. I am even more amazed that these could last 6000 years of geological exposure to natural elements, weather and earthquakes. And I thought the vault was invented by the Romans!

Could these have been fortifications rather than tombs? I say this because of the very low and difficult entrance. This would give defenders inside the upper hand against hostile intruders. The charcoal found inside makes this even more probable. So does the several tunnel entrances. The inaccessibility of this small island except during low tides fits this view as well. These remind me of the stone caves found at Easter Island along the beach.

Were these chamber tombs dated exclusively by the carbon dating of charcoal found inside? What was the source of the charcoal? Could it have been from coal rather than tree? Where there human or animal remains found inside these that could yield some dates too? I feel much more confident dating animals and humans than dating charcoal.



BRIAN JOHN said...

Kostas -- my knowledge of French megalithic sites is very limited! But just a few points in response. I too am amazed that features as old as 6,000 years could have survived in this way. I too thought that the Romans and the early Celtic saints (with their beehive houses or cells made with drystone corbelled vaulting techniques) were the pioneers in this sort of construction........ so some mental adjustments required on that score.

These small chambers could not be fortifications or dwellings -- why would one choose to be trapped in a small chamber with no retreat if attacked by enemies? No -- they have to be associated with burials. The entrances to the passages are very low today, but I suspect that is because a lot of debris has fallen down the front face of the mound and has raised the ground surface . The collapse of the semi-circular mound in front of the tomb has also contributed to this accumulation of debris. It might have been possible to walk -- rather than crawl -- into the passages when the site was in perfect condition.

I don´t know much about what was found inside the chambers. All I know is that the archaeologists were convinced that the debris was associated with burial ceremonies.

Of course, when this site was built and used, sea-level would have been much lower than it is today. So this would not have been an island, and the terrain around Carn would have looked very different.

Constantinos Ragazas said...


'Fortifications' may be the wrong word for this. A place of 'refuge', like a cave, is closer to what I had in mind.

Were portions of the interior of these chambers part of caves? Or the entire structure was built by men using stones and slabs. I just can't bring myself to believe that such 'stand-alone' vault structure built by men using stones could have survived for 6000 years.

While in Greece one summer as a student I was shown what was claimed by locals to have been stone fortifications dating back to a period before the Doric migration southward. Later it turned out that these were army outposts made during the communist uprising following WWII. I question everything since then!

If the charcoal found inside was from coal or petrified wood, the carbon date so obtained may have nothing to do with the date of the chambers.

I am very skeptical about this!


BRIAN JOHN said...

I'm pretty happy with the dating -- and there are other corbelled vaults of the same sort of age elsewhere in Brittany. Barnenez is by all accounts even more amazing. But dated to the same period.

I too have been fooled by WW11 lookout sites hollowed out in Bronze Age burial mounds -- so I agree care must be taken...... Remember that Skara Brae is also Neolithic, and that's pretty amazing too. But I don't think there is any corbelled vaulting there.....

BRIAN JOHN said...

There are no caves here -- the structure is entirely man-made on the highest point on the island.