Mollusca

Snails at Snail Cave, and elsewhere in Wales

This post has been published on behalf of Dr. Ben Rowson, Senior Curator: Mollusca at Amgueddfa Cymru – National Museum Wales.  

I am not an archaeologist. Instead, I am a specialist in non-marine molluscs (slugs and snails) at Amgueddfa Cymru – National Museum Wales, Cardiff. Nonetheless I have the occasional privilege of working on molluscs from archaeological sites, and today is one of those “inter-disciplinary” days.

My usual role is to sort and identify any molluscs from the excavations (which can range from easy to very difficult) and to comment upon their possible significance. In this brief blog I can only give a flavour, but a great new book now exists for anyone keen to learn more (http://www.oxbowbooks.com/oxbow/molluscs-in-archaeology.html).

There are three main roles of molluscs in archaeology. Two are as old as humanity itself.

Snail Cave, North Wales (photo by George Smith)

Firstly, food. Barring religious taboos, inexplicable cultural preferences, and indelible experiences of food poisoning, edible shellfish have been important since prehistory, as attested by shell middens at countless occupied sites. When archaeologists first excavated Snail Cave, a prehistoric rock shelter near Llandudno, North Wales, they found it dominated by shells of the edible winkle Littorina littorea and other edible rocky shore molluscs. Many of the shells were intact, suggesting that they were “winkled out” with an implement, something almost impossible without first cooking the snails. Seasonal shellfish harvesting was a likely function of the shelter, perhaps in the autumn. Did some Mesolithic months have an “r” in them too?!

The Mesolithic cowrie bead from Snail Cave

Snail Cave also yielded evidence of a second ancient use of molluscs: the manufacture of artefacts. A single perforated bead made from a shell of a northern cowrie Trivia cf. arctica was present in the deposits. This was only the second such bead yet found in Wales, probably dating to the Later Mesolithic age like others found the Britain and Atlantic Europe. The holes appear to have been pierced deliberately to string the bead. Cowrie beads, of course, can still be seen adorning necks, wrists or ankles in the seaside towns of Britain today. And cowries are catnip to shell collectors of all ages.

A snail community in situ, preserved in marl near Monmouth (photo by Stephen Clarke)

In south Wales, my young daughter and I find that Trivia is just rare enough to be worth hunting for, yet common enough to be confident of finding at least one during a summer’s day down the beach. Their eye-like shape gives them a mystic air; in Welsh they are the Cragen Fair (“Mary Shell”), perhaps denoting a more religious power; and in much of the world cowries were literally what wealth was made of. For me personally, there are few better examples of archaeology’s ability to connect us to the past than to imagine that prehistoric beachcomber, feeling just as I do when a cowrie winks up from the sand.

Another snail community characteristic of its habitat (in this case, sand dunes)

The third role of molluscs in archaeology requires shells not touched by human hand. Terrestrial molluscs – most of which are small – can live and die in tiny patches of the right habitat, yet their shells can persist for millennia. This can make them excellent indicators of past environmental conditions. The reconstructive use of land snails in archaeology was pioneered by John Gwynne “Snails” Evans (1941-2005), whose collection now resides at Amgueddfa Cymru. From time to time I have identified snails in the same vein, most recently from excavations near Monmouth, where a rich mollusc fauna thrived beside what is thought to have been a large post-glacial lake. Currently, I am working on material from far earlier in our prehistory – from hominin sites in Africa –– but that will merit a blog of its own another time.

I would like to thank Elizabeth Walker for introducing me to the work at Snail Cave and in Monmouth and Matt Knight for inviting me to contribute a DoA blog.

A Lab Full of Shells

In the archaeology lab at the Virginia Museum of Natural History (VMNH), I am continuing work on an assemblage from a site that I posted about for Day of Archaeology 2011 (http://www.dayofarchaeology.com/a-quiet-day-at-the-lab/), the Barton Village site. Located in western Maryland on the Potomac River, this multicomponent village site has been the subject of excavations for over twenty years by Dr. Bob Wall at the Towson University. The Barton site has yielded a large quantity of faunal remains – the boxes of bones fill an entire industrial shelving unit. When working with an assemblage this large, I generally sort, identify, photograph and capture data one bag at a time, with each bag from a separate provenience. This site has some interesting materials though that are worth removing from the rest and looking at separately. Specifically, this site has a fairly large number of mollusks.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

When a site has a lot of mollusks, I find it useful to pull out all of them and identify them all at once. When working with a lot of the same thing, I find my identifications are more accurate and consistent if I do a lot at once instead of one this week, two next week, and so on. It also reduces the number of times I have to pull out specimens from the reference collection and is more efficient with my time.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

In this photo you can see some reference material on the back of the counter and the archaeological specimens toward the front. This is a small portion of the mollusk reference material at VMNH. We have over 50 species of bivalves just from Virginia in our collection.

The mollusks from the Barton site make an interesting sample. So far we have identified almost 20 species of bivalves and gastropods – mussels and snails.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

Shells at the Virginia Museum of Natural History in the lab of Dr. Elizabeth Moore.

The stack of plastic boxes in the photo is just the shells that have been sorted and identified and rehoused so they don’t get crushed. There is another entire box of shells yet to be identified. One of the specimens we have identified is from the genus Marginella, a sea snail whose closest source would be from the Atlantic coast almost 150 miles to the east. Marginella were frequently traded by Native American tribes in the east and can be found at many sites. The rest of the specimens identified so far are freshwater species and were probably gathered locally for eating or for bead and tool making. Two of the larger specimens of freshwater mussel were modified into scrapers with serrated edges. One of the species identified was thought to have been introduced to the Potomac in the late 19th century, but its context here is 17th century. I’m withholding the name here because while I have had the identification reviewed and confirmed, the publication extending the range of this species is not yet out.

If you want to learn more about eastern mollusks, you can find some great information, identification keys, and manuals at http://naturalsciences.org/research-collections/research-specialties/invertebrates/arthur-bogan.