Iron was a valuable and
coveted product in medieval and pre-medieval Scotland; by way of illustration, there
is a classic ‘dog-in-a-manger’ anecdote from the end of the first century A.D.,
when the Romans were grappling with the issue of what to do with the
recalcitrant peoples of the Highlands. In the wake of the famous battle at
Mons Graupius, Agricola and his troops
built a 22-hectare legionary fortress at
Inchtuthil, near present-day
Blairgowrie, on the hinge between Strathmore and Strath Tay. But the site was
abandoned a few years later, seemingly in a hurry, and ten tons of iron,
including over a million nails, were buried in a deep pit inside the fort.
Clearly the departing troops lacked the time or the means to transport such an
impressive stockpile away with them, but were under strict instructions not to
let any of it fall into the wrong hands.
But then the natives were
also quite capable of making the stuff for themselves, and had been doing so for
many centuries. At Beechwood Farm to the east of Inverness, where new buildings
for the University of the Highlands and Islands are under construction, archaeologists
have come across the remains of an ironworking hearth, an early form of the
‘bloomery’ used to smelt iron before the invention of the blast-furnace. The
structure is surrounded by deposits of slag, the waste-product formed at
various stages of smelting and smithing. Its discovery marks another
contribution to our understanding of how society and economy operated around
the Moray Firth, one of the crucibles of Scotland’s pre-history.
Map of the Moray Firth, © Wikipedia Commons
Power was visibly
concentrated in this corner of Scotland in the early-historic period: forts
like the massive enclosed promontory at Burghead, and later monasteries such as
the celebrated foundation at
Portmahomack
on Tarbat Ness, speak of a society ruled over by potentates with extensive
command of resources and populations. This ‘landscape of power’ can be traced
in various manifestations until the onset of the Viking Age: the lands around
the Moray Firth have one of the highest concentrations of Pictish sculpture in
the whole country, and if we take Adomnán’s
Life
of Columba at face-value, it was from here that king Bridei ruled over a
wide hegemony in the mid-sixth century. Bridei’s ‘capital’ may have been
located at the hillfort on Craig Phadrig, just to the west of modern Inverness.
When the region finally emerges in the slight documentary evidence for the
seventh and eighth centuries, it is under the name of
Fortriu – of all the divisions in the murky political landscape of
Pictland, it is by far the best attested.
All this must have
entailed resource control, principally in terms of agricultural produce and
livestock. But over the last decade or so it has become increasingly clear that
the lands at the north-eastern end of the Great Glen were also home to a number
of centres for proto-industrial activity. There was a major hub for iron
production at Culduthel, to the south of the city, where among a cluster of
roundhouses many of the structures were found to contain hearths similar to
that unearthed at Beechwood, their floors fused with a crust of iron slag. Nearly two hundred finished iron artefacts –
mostly weapons and tools for working wood, leather or metal – were recovered from the
site, along with a quarter metric tonne of iron slag.
At another site at
Dornoch, thirty or so miles to the north, similar activity continued into the
viking period and beyond (a new forge was erected there as late as the
fifteenth century). But the sequence is now being extended further back as well.
There is a bloomery furnace near Forres dated to between 400 B.C. and 100 A.D. Carbon-dates
provided so far at Beechwood Farm suggest that smelting activity took place
between 400 and 100 B.C. – that is, in the pre-Roman Iron Age. In this respect, the cumulative impression is one
of considerable economic continuity in the region.
All of this begs the
question of where the iron ore came from (the only other raw ingredients needed
for ‘bloomery’ smelting are wood to burn, and a good water supply). The Romans
had plenty of iron mines in Britain, and most of their ore came from the Weald
of Kent and the Forest of Dean. As for Scotland beyond the limits of empire, there
are (or were) rich deposits of iron ore – on the island of
Raasay, for instance, over on
the west coast. Haematite and magnetite is found in small concentrations in the
older schist and gneiss rocks of Skye, Shetland and Kishorn. None of these are
known to have been mined before the seventeenth century, however, and it is
thought that virtually all of the iron smelted in earlier times was produced
from a regenerative source called ‘bog iron’. This typically forms where
iron-bearing ground water rises to the surface, where (possibly aided by
bacteria) an oxidised crust of iron ore forms. After ‘harvesting’ the crust can
reform within as little as two decades – a superb example of a renewable
resource being exploited in a proto-industrial context.
Formation of Bog Iron, photograph © United States Geological Survey Commons
Elsewhere in Scotland,
there is a definite link between metal-working and aristocratic (or even royal)
status in the early historic period, for example at
Dunadd, in Argyll, or at
Whithorn and the Mote of Mark in far-off Galloway. Jewellery manufacture, at
any rate, and other forms of advanced metal work, were the preserve of the
elite (including the clergy) and the craftsmen they controlled. Smelting
presumably took place
in situ, with
the traces usually found nearby.
The
earlier examples in Moray are in some respects no different: the Culduthel
furnaces surround one of the largest roundhouses ever found in Scotland, twenty
meters in diameter, and there is evidence at the site for prestige activities
like glass production and bronze-working. But there are also signs, at Dornoch,
that iron smelting sometimes took place in a rather cosy domestic context,
perhaps little separated from the supply and preparation of food. How the
Beechwood furnace fits into this wider picture remains to be seen.
