Wednesday, 18 April 2012

Limpets and the stone age rock shelter

Above Pont Garreg Hylldrem, where the road from Llanfrothen turns a leftwards right angle towards Beddgelert, there’s an overhanging cliff popular with climbers. It was popular with stone age hunters too, not for climbing but for the welcome shelter of the overhang on a platform about ten metres up from the sea or estuary below.

Local resident Clive Hudson was climbing there on Christmas Day 2007 (I didn’t ask why or whether it was before or after lunch) when he spotted a limpet shell wedged within a crevice. How had it got there?

Subsequent excavation, under the supervision of Bangor University, has uncovered several hearths and many shells: oysters, cockles and winkles as well as limpets. Mixed in were pieces of bone, probably deer, and so far 42 pieces of worked flint. Three limpets from different parts of the site have been carbon dated as being from 7379, 9281 and 9349 years ago.

Under normal soil conditions the high levels of acidity in north Wales would have caused the shells and bones to disintegrate but lime, seeping out of the overhanging rocks, has altered the chemistry thereby preserving these relics. Just a short distance beyond the overhang and normal acidity returns. 

Dr Gary Robinson, lecturer in archaeology at Bangor, describes the site as a hunting camp used on a regular basis for a few days at a time before returning to the home base. ‘It might have been for three or four hunters out on an expedition, maybe pursuing deer or spawning salmon on their way upstream. ‘

The low volume of shellfish remains suggest that these were snacks as opposed to the main diet of the hunters. Strangely one of the mussel shells is a species never before found in Wales but present in the Mediterranean. Was the sea warmer all those years ago?

Towards the end of the dig, in April 2012, a flint arrowhead was discovered, probably dating back to the bronze age. If that's the case, then this rock shelter was used for 5000 years. 


  1. The ‘Mediterranean mussel’, which has a hooked shell, is Mytilus galloprovincialis.

    Ivor Rees has pointed out that the mussel we are used to, Mytilus edulis, can also have hooked shells if they grow closely packed together so other characters have to be looked at as well.

    He also says that the National Biodiversity Network Gateway website has records of Mytilus galloprovincialis in Pembrokeshire and in Tremadog Bay.

  2. And of course the best place to start if you want to identify mussels is the brilliant website developed by the National Museum of Wales