MDE13172 - Iron Age or Roman iron smelting bloomery at Sherracombe Ford (Monument)

There is an openworking immediately adjoining the slag heap at SS 7210 3670, but it does not look big enough to have furnished enough ore for all the slag on site. Another large slag heap at SS71903665. Iron smelting site observed at Sherracombe Ford on High Bray/North Molton parish boundary. Large heaps of scoria or slag. No iron mine known in the immediate vicinity, though numerous ones lie further south in North Molton parish. Late 16th or early 17th Century date suggested. [1] The slag is from a bloomery, dating from between 500 BC and 1700 AD. A medieval date is most probable. [2] Most probable source of iron ore was Roman Lode workings, part of Cornam Ford Mine in Somerset, SS749383. [3] A calibrated radiocarbon date from slag at this site gives dates of 1st century AD/BC. Exmoor National Park. [4] There are two principal slag heaps, one beside track at Sherracombe, the other about 100 meters upstream. At this latter site considerable amounts of iron slag are eroding into the stream along a circa 35 meter frontage. There are probable working platforms above and between the heaps and also earthwork terraces on the slopes southwest of Sherracombe Ford. A single sherd of probable Romano-British imitation Samian has been recovered from a molehill on one of the main platforms by Exmoor National Park Authority archaeologists. The site has been surveyed by the Royal Commission on Historical Monuments in England. [5] Radiocarbon date obtained from roundwood charcoal from primary smelting deposit of heap beside Sherracombe Ford. Date of 2000+/-50BP, calibrated to 160BC-AD90. [6] SS 7200 3665 The remains of an iron smelting site, or bloomery, evidenced by slag heaps, working platforms and building stances all situated along the northern bank of the stream at Sherracombe Ford. There are three slag heaps, all turf covered but showing clear evidence of slag. The main heap, about 50 metres long by 20 metres wide, northeast by southwest, and about 4 metres high, is to the immediate north of the track at about SS 7197 3663. To the south of the track at SS 7193 3662 is a probable extension of the main heap about the same size and further east some 150 metres up the stream at SS 7208 3667 is another slightly smaller one. The access to the site from Sherracombe Lane, i.e. the old Sherracombe Ford, has been built over by an embankment and the stream culverted. Centred about SS 7199 3668 and running up the northern slope is a long narrow wet gulley which is densely overgrown. A stream issues from its lower end. On first appearances it is reminiscent of a costean trench, a linear openwork or collapsed adit but there is no associated spoil heap at the lower end to support this assumption so it is probably a natural spring. There are about five small levelled areas, each about 15 metres square, three centred about SS 7193 3664 and two about SS 7205 3669, which could be openworkings but are more probably stances for buildings. A smaller platform area up the slope about SS 7191 3668 appears to be formed by small trial pit with its spoil on the lower side. Claughton [8] suggests the site is an early tap slag bloomery and reports that dowsing on the site, which highlighted sites of buildings, suggested 15th century date. Claughton says the site could date from any period from early to late medieval but is probably 15/16th century. There are not enough workings on this site to support the amount of slag and it has been suggested that the ore may come from the "Roman" workings at Burcombe some 3.5 kilometres to the northeast as there is no trace of slag there, but as yet there is no definite proof to support this. Note: This site is extremely important due to the sparsity of other bloomery sites on Exmoor. The National Grid References given are provisional only and are based on a 1:10000 sketch transferred to the 1889 Ordnance Survey 1:2500 map enhanced with superimposed grid for clarification. [7,8] Surveyed at 1:1000 scale, March 1996. [9-11,44] A slide of slag from this site showed a large piece of tap slag of the type associated with Roman dates in the Blackdowns. Earthworks suggestive of structures also visible (on slide shown by Rob Wilson-North at 'Archaeology of Mining in South West Britain' Conference, April 1996). [15] A charcoal sample taken from slag heap A, close to the track has provided has been radiocarbon dated, producing a calibrated range of BC 160 - AD 90, dating the earliest evidence for smelting to the Late Iron Age or Roman periods. [16] A second sample was taken from slag heap B. During the sampling process a sherd of Samian pottery was also recovered, from a sealed primary waste deposit, confirming the probable Roman date of this site. The charcoal sample from slag heap B returned a date of BC 170 – AD 75. [17,18] Magnetometer scanning provided a rapid and non-interventionist means of determining how far slag extended beyond the visible features of the site. [19] Charcoal analysis indicates the use of oak and hazel, ash, birch, alder, willow and the hawthorn/rowan group during metal-working on-site. However, oak and hazel were predominantly being exploited for fuel, bothas roundwood and largewood, probably from both coppiced and non-copiced sources. Evidence from secure contexts within slag heaps A and B indicates that oak and hazel were being specifically selected for the smelting process. The evidence supports an interpretation of a stable contemporary local environment throughout the 300 years of iron-working, of a predominantly oak and hazel wooded valley and hillslope with birch on the higher, poorer soils. Alder and willow may have been more common on the lower damper soils. [23,24] An excavation was undertaken at Sherracombe Ford at SS 7198 3664 in 2002 to investigate the nature, scale and chronology of iron production on one of the larger double platforms and the adjacent slag heap. The platform contained the remains of three furnaces with a smithing floor producing finished iron. The platform was created by a succession of clearing, re-cutting and levelling events and the footings of several mortared stone walls were excavated. Geochemical surveys identified metal working areas and slag heaps. Excavation of the slag heap exposed stratified layers of charcoal and slag. [25] Gradiometer and resistance prospection surveys took place in March 2002, highlighting possible areas of ironworking activity for excavation. Further high-definition surveys were completed during the subsequent excavation in August and September 2002. [26] A significant find at Sherracombe Ford was the discovery of a compacted smith workshop floor, the presence of which was initially indicated by geophysical and geochemical survey. The floor and its surrounding area were intensively sampled. [29] The retrieved ceramic assemblage, the majority of which was retrieved during the 2002 and 2003 excavations, identifies a period of activity dating from the early 2nd century possibly into the early 4th. Preliminary assessment indicates that the assemblage is dominated by local or regional coarsewares, with finewares and amphorae present in smaller numbers. [30-32] Excavation took place as part of the Exmoor Iron project in 2002 (4 weeks), 2003 (6 weeks) and 2005 (3 weeks). Stratigraphic analysis in conjunction with the ceramic dating evidence divides the occupation of the site into four main phases: Phase 1: late 1st – early 2nd century AD Phase 2: early second – mid 2nd century AD Phase 3: mid 2nd – mid 3rd century AD Phase 4: mid 3rd century onwards. AD A further 20 radiocarbon dates were obtained from contexts of technological debris sampled throughout the site. These suggest that slag heaps A and B are contemporary, arising from smelting occurring between the late Iron Age and the late 3rd and early 4th centuries AD. The discrepancy between the earliest radiocarbon dates and earliest ceramic evidence is yet to be resolved. It is possible that the earlier dates indicate the real situation, or may have arisen from differing laboratory procedures or may indicate a degree of lateral stratigraphy on the site, arising as they do from samples taken during the preliminary survey some 20 metres from the location of the later trenches. To complicate matters, archaeomagnetic dating of a well preserved furnace setting from trench 2 on platform A returned a date within the mid-late Iron Age, contradicting the radiocarbon and ceramic evidence placing this feature in Phase 3 (mid 2nd – mid 3rd century AD). Nonetheless, the main activity on site began in phase 2 and ended with phase 3. [28,29,31] During 2003 the peat deposits within the flush running through Sherracombe Ford were assessed with the aims of identifying the age of the flush, its relation to the iron working activity in this area and whether or not it could provide environmental context for the Romano-British industrial activity at Sherracombe Ford. The results indicate that the Sherracombe Ford flush correlates with the highest pollen zone at the nearby site at North Twitchen Springs, probably dating to circa AD 1750 or later. The flush therefore post-dates the Romano-British period and has little potential for research into the iron production working at Sherracombe Ford. [34] The gradiometer survey results from Sherracombe Ford [26] were integrated with geochemical prospection data and the results assessed using a GIS. The results show a high degree of correlation between the two techniques, suggesting possible value in application of this method on other possible iron-working sites. [35-36] Samples from two clay deposits from the excavated furnace at Sherracombe Ford were submitted for archaeomagnetic dating. The samples were taken from the upper and lowermost identified layers, i.e. those identified as the youngest and oldest layers. The samples returned dates (i.e. most-likely last-heating dates) of circa 40 BC and circa 350 BC. Although the actual dates are significantly older than those returned by radiocarbon dating, the span of activity indicated is comparable. [37] SS 719 366. Sherracombe Ford is an example of a site with an abundance of charcoal present where direct processing of iron ore took place. It was identified by the late John Rottenbury. [43] This record was enhanced as part of the National Record of the Historic Environment to Exmoor National Park Historic Environment Record data transfer project. [45] A discussion of geochemical survey at the site was published in 2013. [46] Radiocarbon dates from samples from the site submitted between 2002-3 have been published by Historic England. [47]