|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|
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 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?