EMAP_2012_Report_6_1.pdf (7.3 MB) - The Heritage Council

superstructure (ibid. 117). A few ambiguous fragments of possible clay superstructures have
been noted by Comber (ibid.) at Garryduff, Letterkeen and Rathgurreen. A growing number
of smelting furnace sites also contained tuyères for example at Carrigoran and Dunlo and this
may suggest they were used in primary smelting or that bloom smithing occurred alongside
(Young 2010, 3).
Site No. F. Iron
waste
Smelting
furnace
Context Other activity Site
date
Ref.
Johnstown 11 558 2000kg 0.6
x 0.63
x 0.11
Cemetery
settlement
Bloomsmithing/
blacksmithing
C5th-
C17th
Photos
-Jones
2008a
Killickaweeney 6 561 86kg 0.4m
x 0.19m
Univallate
enclosure
Bloomsmithing/
blacksmithing
C7th-
C10th
Photos
-Jones
2008b
Derrinsallagh
3
4 819 60kg 0.45
x 0.40
x 0.22m
Univallate
enclosure
Bloom refining
C7th-
C10th
Young
2008a
Gortnahown 2 3 548 158kg 0.48m
x 0.46
x 0.26
Univallate
enclosure -
Smithing,
bell manufacture
C5th-
C7th
Young
2009b
Carrigoran 2 767 30.4kg 0.5m
x 0.11
stone
enclosures
Blacksmithing
C9th-
C11th
Young
2006c
Dunlo 2 5 12.3kg 0.56
x 0.53
Lisanisk 2 537 827.8kg 0.94
x 0.79
x 0.39m
Isolated Bloomsmithing C10th-
C11th
Bivallate
enclosure
Bloomsmithing
C7th-
C10th
Young
2010
Photos
-Jones
2010
Table 2.1: Recently excavated sites with smelting furnaces, number of furnaces,
example of furnace dimensions and context.
There is also significant evidence of smelting from analysis of metallurgical debris on sites
which do not have excavated furnaces. A good example of an isolated smelting site including
a very large dump of slag was found at Cloonafinneala, County Kerry (up to 520kg of
metallurgical remains of which approximately 5% was sampled). It had no evidence for
bloom refining and appears to be related to primary smelting which appears to be fifth/sixth
century A.D. in date (Young 2012, 4). This site was close to woodland and sources of ore and
included a charcoal production pit. At a range of other sites which did not have excavated
furnaces the smelting slag was a small component of the overall metallurgical remains which
otherwise related to smithing for example at the univallate settlement at Sallymount (Clark &
Long 2009). Frequently sites without excavated furnaces or specialist metallurgical reports
indicate the presence of furnace bottoms for example the cemetery and settlement at
Knoxpark which records eight (Mount 2010, 208). Without indications of size and further
analysis it is difficult to say if these resulted from smelting.
Carlin (2008, 93, 107) has suggested that there may have been a progressive shift from slagpit
furnaces (low-shaft furnaces) to slag-tapping furnaces in places where smelting was
reliant on solid rock ores. Slag-tapping furnaces were much more efficient as they allowed
the slag to flow outside the structure and were the dominant form in Roman Britain and for
much of the early medieval period in both Britain and Europe. However, they never appear to
have been built in early medieval Ireland where bog ore was the dominant source of iron and
this might suggest a link between the smelting of bog ores and the non-slag tapping furnace
types (ibid. 93). The earliest definitive Irish evidence for tapping slag furnaces seemed to be
a number of sites dating to between the eleventh and thirteenth century (Dowd and Fairburn
2005, 115-21). Photos-Jones (2008a, 233) has noted that despite the intensity of iron-ore
processing (2,000kg of early bloomer slag) at Johnstown 1, there was no attempt to progress
from bowl furnace to tapped shaft-furnace technology. Indeed, up until 2006 there was no
published unequivocal evidence for the use of shaft furnaces in early medieval Ireland
(Photos-Jones 2011, cxxi). Some recent excavations do suggest more complex structures
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