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MHG62067 - Late medieval/early post-medieval iron bloomery - Craggie, Glen Oykel

Summary

A late medieval/early post-medieval iron bloomery at Craggie, Glen Oykel, Sutherland.

Type and Period (1)

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Full Description

A late medieval/early post-medieval iron bloomery at Craggie, Glen Oykel, Sutherland.

Spreads of iron slag were found at Craggie, Glen Oykel, Sutherland in 2010 by J Wombell of NoSAS during fieldwalking being undertaken as part of Historic Assynt's 'Assynt's Hidden Lives' project. The slag was found in an area recently mounded for tree planting by Forestry Commission Scotland. <1>

GUARD Archaeology were commissioned by Forestry Commssion Scotland to evaluate the area in September 2010. Prior to excavation, a phase of artefact recovery and survey was conducted to remove all of the slag from the exposed mounds and pits. Two trenches were subsequently laid out, each approximately 5m × 3m. Trench 1 was located over a block of slag evident in pit 34 and oriented north-west/south-east. The second trench was positioned at right angles from this, with a small baulk (c 200mm) separating them. Excavation of trench 1 revealed the remains of an oval furnace bowl founded upon an old ground surface, sitting over the natural sand and gravels of the terrace. The furnace bowl was 0.9m × 0.6m and oriented north/south. Constructed mainly of friable slag material, which sat over a thin band of heat-affected red clay, it had a profile that included a distinct overhang along the eastern interior. No visible sign of a tuyere hole was evident, however, the most likely position for this and the associated bellows was on the higher ground to the west. This side had been badly damaged by pit mounding operations. The bowl contained traces of the final firing in the form of a charcoal and slag-rich layer. Analysis of the charcoal revealed that birch dominated the fill, with small traces of alder present. A sample of birch round wood was selected for dating and returned a date range of cal AD 1470– 1650 (SUERC-32846, 2σ). A further discrete sample of birch charcoal was also recovered from beneath the furnace bowl. This was also dated and returned a range of cal AD 1490–1670 (SUERC-32845, 2σ). Excavation of trench 2 revealed two linear features running broadly north-west/south-east across the trench. One was narrow and shallow and could be the base of a furrow associated with post-medieval cultivation of the terrace. In contrast, the other was kidney-shaped in plan and had a lower deposit of charcoal-rich silt, capped by a silting layer. The lower deposit also contained slag fragments in great numbers and the cut of the pit showed a distinct variation in colour, which may imply burning within the pit. Within Scotland, Craggie is notable as a rare example of a previously unrecorded bloomery scatter and especially important given the identification and excavation of a furnace at the site. The furnace is also exceptional in terms of its scale and construction. The two dates recovered from Craggie were statistically identical and seem to suggest that the furnace was only used for a short period of time between the late 15th and early 17th centuries. <2>

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Map

Location

Grid reference	Centred NC 3361 0516 (4m by 4m) (2 map features)
Map sheet	NC30NW
Geographical Area	SUTHERLAND
Civil Parish	KINCARDINE

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