Something fishy this way comes...

It's been a very strange and difficult year for everyone and we hope that you and yours are in good health and coping with the current situation. Since our 2020 excavation was cancelled, along with all other Orkney excavations, the Orkney branch of Team Swandro has been using the time to catch up with the processing of the environmental samples and the soul-destroying task of residue sorting. I'm pleased to report that we have now cleared the backlog and sorted all the residues, and have only gone slightly insane in the process:


In case you're wondering that's hammer scale (the stuff that flies off when you whack very hot metal really hard, and indicative of high-status metalworking) from a sample from our smithy, extracted by magnet rather than by hand thankfully. The magnet makes life much easier although you do have to remember to wrap a piece of card around your magnet before you start, otherwise you have the much more difficult task of picking hammer scale off a magnet. The hammer scale will go off to be analysed by our archaeometalurgist Dr Gerry McDonnell, seen here in the smithy itself:


All I can say is that it's a real pity that fishbone isn't magnetic too, that you have to do it all by hand with tweezers & sieves. That doesn't sound so bad but considering the biggest of the fish bones are all pretty much the size you'd get in a tin of sardines and a lot are much smaller it can take several days work to pick them all out from a big pile of shale - the bigger bones in the photo are rodents, the fish is all the tiny brown bits:


You know that you've sorted too many fish bones when you're dreaming about them too and yes sanity is definitely beginning to crumble by the end of it, but you have to keep telling yourself that you'll make the fish bone specialist very happy:


Seriously it is worth the effort as the only way you're going to get recovery of the tiny fish bone is from sample residues, although you can hand collect the larger ones during the excavation. We do have an awful lot of small fish bones in very concentrated Iron Age deposits, some of which are associated with hearths, and we've been wondering just what's going on here. With the larger fish bones it seems obvious that they're eating fish for their tea, but why are we getting loads of tiny bones? You'd think that if they were eating these little fish then they'd be crunching up the bones and eating them too (like you do with sardines and sprats for instance), but the way we're getting large discrete deposits suggests possible fish processing, for something where you didn't want the bones - maybe fish sauce?

It's not as daft as it sound since fish sauce has been around for millennia and our old friends the Romans were very into their garum (although apparently I've been getting this wrong for years as I just assumed that garum equalled fish sauce, but it's specifically fish sauce made from fermented blood and guts). Sauces were made from whole small fish, notably liquamen, which was fermented and then strained, and so would give you a residue of small fish bones like the ones we've got at Swandro. There's a very good paper free to download 'Roman Fish Sauce: Fish Bones Residues and the Practicalities of Supply' by Sally Grainger who spent three years fermenting fish in her greenhouse and documenting the results - there's dedication for you. She used her greenhouse to get the temperature right - it's mostly too cold to naturally ferment fish sauce in Britain, so locally produced fish sauce would need to be done somewhere warm, and in the absence of any evidence for Iron Age greenhouse close to the hearth would work fine.

Fish sauces were produced in the Mediterranean areas and exported all over the Roman Empire but they could be made locally and there is archaeological evidence for this (e.g. in northern Gaul). Although we don't have evidence for a Roman presence in Orkney we do have evidence for Roman finds at high status sites, such as Swandro's piece of prismatic Roman glass bottle from the 2019 excavation:


I know next to nothing about Roman glass, but I do have a copy of Dominic Ingemark's excellent book 'Glass, Alcohol and Power in Roman Iron Age Scotland' and he suggests that prismatic bottles were used for defrutum, wine or olive oil, more for serving & local storage rather than long distance transport. What's defrutum I hear you ask? Well, here the plot thickens - just across Eynhallow Sound from our site at Swandro lies the Broch of Gurness, where, during the 1930s excavation, a couple of pieces of Roman amphora were recovered:


The amphora was identified as a Camulodunum 185A, better known as Haltern 70 a type known (from surviving inscriptions) to used up to AD70 for export of defrutum, or of olives preserved in defrutum. Opinions on defrutum (as in just about everything to do with archaeology) differ - it's generally thought to be a sweet boiled down grape syrup, used in cooking and preserving, or as a wine additive, but it may also be that defrutum was itself a sweet wine. In any case the slightly mind-blowing implications are that an amphora full of a a Roman luxury product was shipped out to the Broch of Gurness sometime before AD70. One of the uses for defrutum in cooking was to make oenagarum, which could be made in various ways involved mixing fish sauce with defrutum or wine and adding other flavourings and using it as a dipping sauce. I now have a picture in my head of Iron Age dinner parties where the folk from Gurness rowed across the sound to Swandro clutching a present of a prismatic bottle full of defrutum and the hosts providing the fish sauce. You probably got more brownie points for having the real Roman defrutum as opposed to homemade fish sauce - or would it be the other way round? Maybe it was like serving home made (probably sourdough) bread rather than stuff from the supermarket, you got extra points for the effort, so home made fish sauce beats ready made defrutum? OK maybe this is one digression too far, but you do have a lot of time to think when you're mindlessly picking out little bits of fish bone from shale.

There have been a few star finds breaking up the fishy monotony though, my favourite is this little pendant:

It's from the Iron Age levels and is made of some kind of tooth, probably from a small sea mammal but that awaits specialist identification. Julie (Bond, site director & animal bones specialist) has only seen the photos so far and wants to see it for real before she commits to a formal ID. You may remember our seal's tooth pendant from the 2019 season, this one came from a closely related context so maybe was part of the same necklace? The photos don't really do it justice, it's beautifully polished and shiny in the flesh, and, more to the point, it definitely isn't a fish bone:

Usually at this time of year our thoughts would be turning to next year's excavation, we'd be finalising dates, recruiting volunteers and generally planning ahead, but at the moment everything's on hold due to you know what. We're hoping to get a longer season in 2021 to compensate for missing out on the 2020 dig, but it all depends on the situation and any government restrictions that may or may not be in place. All of the Orkney excavations are in the same boat, and we're all keeping our fingers crossed that 2021 turns out to be a better year for everyone than 2020.

Of course now that all the flot residue's sorted and lovingly bagged and packed ready for the specialists the Orkney members of Team Swandro need to do something else to while away the long Orkney winter - apparently there's lots of things you can do with limpets these days (apart from chuck them away and pretend you never found any - only joking Julie!) starting with measuring them and working out their conicity - apparently limpets that grow in the upper areas of the beach are pointier than those that grow lower down because they have to hang on harder as they're out of the water longer & that affects shell shape - who knew? I think that might be a subject for another newsletter, meanwhile here's some of them to whet your appetite - bon appetit!


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Swandro - Orkney Coastal Archaeology Trust 

Scottish Charitable Incorporated Organisation No: SC047002 

Patron: His Royal Highness The Prince Charles, the Duke of Rothesay

Registered office: Bayview Birsay Orkney KW17 2LR   email: info@swandro.co.uk