BEDROCKS ANDBULLAUNS: more thanone use for a morta r?Brian Dolan wonders whether complacency has affected the

interoretat ion of bul launs.

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lntroductionBullaun stones are one of those classic Irish

archaeological monuments that everyoneknows about, many have seen, but few have

really thought about in any serious way,

largely because of their seemingly enigmatic

function. They are basically scoops or

hollows in large stones, tlpically lacking

any fill or context that might betray their

functions.My interest in the role-or multiple

roles-of bullauns in the past was piqued

when reading a recent article in ArchaeologyIreland (Autumn 2008) by Matt Kelleher and

Caimin O'Brien which discussed some stone

basins, cut into bedrock underlying peat in

Meelaghan, Co. Offaly, that look very

similar to stone mortars used for grindinggrain in a number of Native American

cultures. The authors suggested that these

features do not fit into the traditional

understanding of bullauns as 'a single

depression found in association with an

ecclesiastical site' and should be classifiedseparately as 'bedrock mortars', implying a

use in food production.What struck me, howevet, was how

similar these stones also are to mortars forgrinding iron ores that I have seen in the

archaeological literature. The idea of

bullaun stones being used for the crushingof metallic ores is not new but it has beenoverlooked by Irish archaeologists in favourof interpretations focusing on theprocessing of grains, nuts and seeds or on

religious/ritual explanations. Further

research made clear that associations with

early metalworking may be significant for atleast a subset of bullaun stones and, moreimportantly, that this could be testedthrough both excavation and survey.

Previous researchThe seemingly intractable nature of bullaunstones has meant that few have thought to

study them, let alone define orsystematically analyse them. Hypothesesregarding their function have changed little

since they were first identified in the late

nineteenth century, and the last maior

article on the topic, published by Liam Price

exactly 50 years ago, still awaits an update(although significant work has been carriedout recentlyby David McGuinness as part ofa doctoral project in UCD). There is ageneral acceptance, based on their

Archaeology lreland Spring 2009

Opposite page: Bullaun stone fromGlendalough, Co. Wicklow (photo: TerryO'Hagan).

Right: Conical ore-crushing hollows fromMugharet al Warda, Jordan (photo: Yosha Al-Amri).

consistent association with earlyecclesiastical sites, that the stones date fromthe early medieval period, but problems ofdefinition, classification and dating stillremain.

Possibly the most crucial issue in thestudy of bullaun stones has been theunverifiable nature of the most populartheories about their use. This is due to a lackof relevant historical sources and theephemeral nature of many of the activitiesthat have been associated with them. Owingto this lack of evidence, interpretations ofbullaun stones have relied heavily onfolklore as well as ethnographic andhistorical analogy.

The use of 'knocking stones' in Scotlandand Ulster in the early modern period forpounding barley and oats, combined withethnographic and historical examples ofsimilar stone-cut basins from across theworld being used for food production, haveprovided the best argument for bullaunstones having a similar use in lreland.

Peter Harbison has convincingly linkedsome bullaun stones in the Dingle Peninsulawith pilgdmage as part of a package ofremains associated with early pilgrim routes.The association of many bullaun stoneswith ecclesiastical sites certainly appears topoint to some form of religious context fortheir use, but evidence of metalworking onmany church sites, such as Clonfad, Co.Westmeath, or Clonmacnoise, Co. Offaly,may point to an underlying industrial causefor the association. This might also explainthe occurrence of bullauns in isolatedlocations and in association with secularsites. Other interpretations of the bullaunsas cursing stones, as having curativeassociations or as baptismal fonts have beenbased on a mixture of conjecture andfolklore. Little or no direct evidence for theiruse, or indeed their date, has been found,and this has forced a reliance on analogyand speculation.

Archaeology lreland Spring 2009

Bullauns and metallurgyVery little is knorrm about the extraction orprocessing of metallic ores in early medievalIreland. It is clear, both from thearchaeological evidence and the texts, that avariety of metals, particularly iron andcopper, were mined, processed and smeltedon a fairly regular basis. No mines from theperiod have been identified archaeologicallybut they are mentioned in the law-tracts.Ore, once extracted, is usually processed, i.e.broken up into smaller pieces, sorted and,depending on the ore, roasted prior tosmelting. A verse in tl:te Dindsenchas of AillnCobthaig specifically mentions the crushingof ore by the Sil mBuinne of Bantry after itwas quarried; unfortunately it is not clearwhether this took place at the site ofextraction or elsewhere.

The crushing and sorting of ore, termedbeneficiation, is necessary in almost all casesprior to smelting. Methods of crushing varyfrom the use of simple stone hammers tothe rolling of hear,y boulders over ore spreadon a flat rock. Two methods known fromIndia result in stone basins or depressionsvery similar to those classified as bullaunstones in lreland. Crushing ore on flatboulders or rock outcrops using hand-heldhammers or pestles produces a shallowdepression which, upon reaching a depth ofc. 10cm, begins to abrade fingertips as wellas ore, resulting in stones with multiple

B U L L A U N S

depressions on their surface. Anothermethod, used in Rajasthan, involves thecreation of large mortars, c. 5Ocm indiameter and 50cm deep, for the crushing ofsilver-lead ores with large iron or iron-shodpestles. Similar mortars, in an outcrop ofbedrock associated with a Byzantine ormedieval iron-mine, have recently beenidentified in Jordan.

Normally, beneficiation is carried out inor close to a mine or extraction site,although in the case of bog ore waterloggedconditions may have necessitatedprocessing elsewhere. The smelting site,which could sometimes have been adjacentto the ore source, may have seen furthergrinding of ore, depending on the metalbeing extracted and the smelting techniqueused. Smelting sites are also often locatedclose to sources of fuel, population centresor in socially prescribed areas.

Superficially at least, an obviousanalogy can be dranrn between Irish bullaunstones and the ore-crushing mortarsdiscussed, but, crucially, there is alsoarchaeological evidence to support thecomparison. Some of the most convincingevidence comes from Gallen Priory, whereKendrick found an ironworking area withdeep pits of iron slag and burnt earth and ahuge stone slab over 2mIong. The slab hada 'basin' 50cm in diameter 'scooped' out ofit, which the excavator presumed was for

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which was interpreted as a potential bullaun

owing to an artificial depression on its

surface. Cut into the fill of the pit was a

possible furnace or hearth bottom lined

with a dense layer of charcoal and slag.

Less direct evidence for the association

of stone mortars with metalworking comes

from the hut site of Glannafeen, Co. Cork,

likely to date from the Iron Age or the early

medieval period. A spur of bedrock running

through the hut, which contained a stone-

lined iron-smelting furnace, had a circular

bullaun-like hollow shown on the plan but

not discussed in the text. At Drumnakill, Co.

Antrim, an early church site, E. E. Evans

noted a large bullaun cut into a flat dolerite

block and surrounded by large amounts of

iron slag. More circumstantial evidence

comes from sites like St Gobnet's House,

Balllwourney, or Clonmacnoise, Co. Offaly,

where both metalworking and bullaun

stones are recorded but with no direct

associations.

Testing the theoryThe evidence outlined above is very

suggestive but not conclusive. The obvious

next step is to identify a representative

group of bullaun stones in a landscape for a

systematic suwey, involving geophysics and

test-pit excavation. The group at

Glendalough, Co. Wicklow, Iocated in a

mineral-rich area, is an obvious candidate.

For example, a magnetometry suwey carried

out in the vicinity of the bullauns, but also

critically further away as a control, could

Archaeology lreland Spring 2009

detect the remains of smelting operations:

ores, roasting pits, slag, hearths and

furnaces. This could be followed up by

excavation to investigate the character of

any anomalies. Further studies could extend

the scope of such investigations to other

sites, such as those not associated with

ecclesiastical or monastic complexes.

If there is a spatial link between bullaun

stones and extraction sites then these stones

may provide signposts for locating

previously unknown mines-and, in the

case of bog ore deposits, long-destroyed

bogs. This would be particularly true of

bullauns in primary locations, such as the'bedrock mortars' proposed by Kelleher and

O'Brien.

Conclusion

Bullaun stones have been known and

researched since the nineteenth century and

it is perhaps this long history that has led to

complacency in their study. In reality, the

term 'bullaun', as used by Irish

archaeologists, is a generic one,

incorporating any hemispherical hollow in

a large stone not demonstrably prehistoric

or natural. It is very likely that the various

depressions we characterise as bullauns

include monuments that do not share a

single chronology or function.

It is hoped that this article has offered

not only a potential use for some bullauns

but also some plausible evidence and a

direction for future study. Further work on

the classification and definition of bullauns

Above left: Possible bullaun stone from theCarrick, Loch Lomond, Scotland (photo

courtesy of David Sneddon).

Above: Ore-crushing mortar fromBofeenaun, Co. Mayo.

and sub-types such as bedrock mortars, as

well as characterisation according to their

location, may provide new insights into

their place in early medieval society and

economy. There is clearly potential to

progress from arguments relying on

folklore, analogy and conjecture to

explanations based on archaeological

real i t ies and methodologies.

AcknowledgementsThanks to Dr Aidan O'Sullivan and Maureen

Doyle for advice and comments on previous

drafts. Thanks also to David Sneddon, TErry

O'Hagan, Conor McDermott and Dr Yosha

Al-Amri for providing images. Finally,

thanks to the IRCHSS and the National

University of Ireland for funding my Ph.D

research. I

ReferencesCraddock, P.T. 1995 Early metal mining and

production. Edinburgh University Press.Kendrick, T.D. 1939 Gallen Priory

excavations, 1934-5. loumal ofthe RoyalSociety of Antiquaries of lreland 69, I-20.

Price, L. 1959 Rock-basins, or'bullauns', atGlendalough and elsewhere. loumal ofthe Royal Society of Antiquaries of Ireland89, 161-88.

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