Pendragon lime kiln excavation part 2 – the final results

Back in September 2019 a team of archaeological volunteers led by Dr David Johnson and supported by Yorkshire Dales National Park Authority (YDNPA) staff assembled in a field near Pendragon Castle in Cumbria. Their mission was to investigate a suspected lime kiln as part of the Westmorland Dales Landscape Partnership’s Monuments at Risk project, which is being delivered by the YDNPA.

My role in all this was to help organise the excavation and manage orders, contractors, permissions, logistics, site facilities, volunteers and health and safety, as well as assist on site with the excavation and site visitors. The sort of things that go unseen, but are needed to make a project happen.

Regular readers might recall the blog post published shortly afterwards, “Excavation of sow (lime) kiln at Pendragon Castle” which discussed the thinking behind the project and the work that was undertaken. You may wish to read this earlier post before continuing on to the final results below.

Summer 2019 excavation

Very briefly, field observation and earthwork survey had previously pointed to the existence of a semi-circular, c-shaped earthwork, comprising a raised bank surrounding a hollow interior. This was located on a slope in the field immediately north of Pendragon Castle. Its situation and character suggested it was a lime kiln. The well preserved and prominent nature of the earthwork led to the idea that it might be associated with the 17^th century restoration of Pendragon Castle by Lady Anne Clifford, in 1660-1661.

The idea behind the project was to investigate the earthwork to establish the true identify of the feature and to discover when it was constructed or used. If it was a lime kiln, was it connected to Lady Anne Clifford’s 17^th century restoration, to earlier phases of construction, or something else entirely?

Prior to the excavation, geophysical surveys were conducted by an external contractor and by Lunesdale Archaeology Society. None of this provided any evidence to counter the suggestion that the feature was potentially a type of lime kiln known as a sow kiln (See: previous blog and http://www.outofoblivion.org.uk/record.asp?id=370).  

The excavation, led by Dr David Johnson for the YNDPA, targeted a little over half the feature and quickly established that it was a lime kiln. Carefully, the volunteers gradually excavated and revealed the kiln, recording as things progressed, and culminating in the excavation of the deposits in sequence which had partially filled in the bowl of kiln and the area of the former flue. A very small assemblage of finds was recovered and a small number of samples of charcoal obtained.

Ideas about the possible date of the kiln gradually evolved during the work, moving away from a 17^th century date towards an earlier origin. It was hoped that the post excavation analysis of the finds and the charcoal (which might produce suitable material for radiocarbon dating) would provide a definite conclusion to this key question. A reminder that you can read more about the excavation and what was previously known about the history of the castle in our two earlier blog posts (excavation, Pendragon Castle). This blog will focus on the final results of the post-excavation work.

Results

The kiln at Pendragon was found to be of a simple construction and crude form, essentially comprising a bowl dug into the hillside, with the up-cast material then built up around it, forming a c-shaped earthwork comprising a simple structure with an earth and rubble bank (Johnson 2020: 25).

Evidence was found on top of the banks of a working surface created from the spreading of up-cast sandstone cobbles and angular pieces, providing a solid surface to aid loading and emptying the kiln (Johnson 2020: 23). There was no evidence of any internal stone lining around the inside surface of the bowl, but there was evidence a layer of sandy silt had been spread around the lower bowl, providing a firm watertight surface (Johnson 2020: 25-26). Nothing remained of the upper structure of the flue passage but the lower remnants of simple coursed flanking walls was evident on both sides, backed by rubble deposits at the ends of the banks (Johnson 2020: 26).

One unusual discovery that defied explanation was that the western flue wall turned outwards around the end of rubble bank, whilst the other side appeared to have been a straight wall, something that has no apparent parallel in locally known sow kilns (Johnson 2020: 26).

The deposits excavated from within the kiln and flue largely related to backfilling events, which postdate the active use of the kiln itself. However, some evidence of the remnants of the fuels used in previous firings was located – for example, fragments of coal, charcoal and carbonaceous shale, with a concentration of this material found on the base of the bowl (Johnson 2020: 24). This is thought to be the last remnants of fuel from previous firing events and the lack of any significant quicklime residue suggests it was very thoroughly cleaned out (Johnson 2020: 24).  

All of these characteristics, the crude rubble and earth construction, the lack of coursed walling, clay or stone lining of the bowl, the use of poor quality fuel, the lack of any evidence for an internal stokehole and unusual flue arrangement, all pointed towards an earlier and certainly pre-17^th century date (Johnson 2020: 37-38). You can explore the kiln for yourself by viewing a 3D photogrammetric model here.

Analysis of the finds was carried out by relevant specialists. These finds comprised four Medieval pottery sherds, two from primary fill layers (i.e. the earlier, lower layers) within the kiln bowl, and two from the subsoil and stone spread on and around the bank top, along with an iron pony horseshoe, plus a single sherd of glass from a secondary fill layer in the kiln bowl (i.e. a later, higher up layer) (Howard-Davis in Johnson 2020: 26; Bradley in Johnson 2020: 28; Johnson 2020: 3). 

The finds provided some intrigue but also potential confusion in terms of understanding the site. The pottery sherds were small and abraded, suggesting they were lying around on the ground for some time where they could be damaged and rolled around before being deposited; they were not freshly broken when deposited in the kiln (Blenkinship in Johnson 2020: 27; Bradley in Johnson 2020: 29). Only one sherd was diagnostic and the sherds were ascribed to a broad date range of the 13^th to 16^th centuries (with one of 12^th to 13^th century), whilst a second specialist argued for a 13^th to 14^th century range (Blenkinship in Johnson 2020: 27-28; Bradley in Johnson 2020: 29).  

The glass item was a rim sherd from a high quality façon de venise vessel, perhaps a bowl of late 16^th of early mid 17^th century date found in elite or high status contexts, which could have found its way to Pendragon as part of Lady Anne Clifford’s household in 1660-61 (Howard-Davis in Johnson 2020: 27). The two pottery sherds from the secure contexts of the primary backfill layers in the kiln bowl do however provide a TPQ (time after which) for these events, suggesting these were deposited no later than the 14^th century (Johnson 2020: 32).

All this provided a potential conundrum, however, as, if the pottery was actually residual (i.e. old abraded material lying around, incorporated into a later deposit), then it was difficult to interpret with which phase of building at Pendragon the kiln might be associated, although its character suggested it was likely of pre-17^th century origin.  There was also no evidence (remembering these finds were from later backfilling events) to suggest how long before these backfilling events the last firing took place (Johnson 2020: 33). Disentangling this all depended on the radiocarbon dating results.

Analysis of the charcoal suggested this was the remnants of kindling used to light the fire and that wood was not the primary fuel (Johnson 2020: 32). Radiocarbon dates were obtained on three samples and these give a range between two dates that the actual date falls within; they do not produce a single specific date. They also reflect the date of death of the parent tree, not the specific moment of the kiln firing event itself. The dates obtained also likely relate to multiple kiln firing episodes. Two samples from the basal fill layer of the bowl and flue relate to an early event in the kilns life between 1033 and 1188 CalAD*, whilst a sample from mid way up the bowl from a deposit plastered around its surface dated to 1161-1256 CalAD, most likely from a later firing event (Johnson 2020: 33-36).

The results, taking the widest date ranges, suggest the kiln was in use between the second quarter of the 11^th century and the mid to later 12^th century, with the later date range possibly taking this into the first half of the 13^th century. But the differences are small and the ranges overlap. They may actually reflect use and re-use events within a few decades of each other (Johnson 2020: 36).

This dating evidence rules out any association with the 17^th century restoration works or the two documented 14^th century building phases associated with the 1309 licence to crenellate, or the repairs and addition of the south-west tower in the 1360s following damage in 1341 (Johnson 2020: 33). The kiln most likely relates to the lime needed in the initial construction of the castle and episodes of building in the 11^thor 12^th century.

The results may also offer support to the idea of an earlier pre-1200 small tower house or castellet having preceded the present castle structure (Clark 1883: 49; Johnson 2020: 33). It has been claimed the castle originated as a Norman structure with Ranulph de Meschines and also asserted it was built circa 1180 for Sir Hugh de Morville, while the radiocarbon dating evidence could be used to imply use of the kiln in either or both of these periods  (Whitaker 1805: 308; Curwen 1913: 66 Johnson 2020: 34-36).

*Cal AD, abbreviation meaning this is a calibrated radiocarbon date.

Conclusion

The project has successfully answered its key questions, proving that this feature was a lime kiln likely relating to the 11-12^th century building phases of the castle and not the 17^th century restoration. It just goes to show that you never know what you are going to discover and archaeology is always full of surprises.

The project also provided training for the volunteers and an opportunity to educate many visitors on lime kilns and the history of the castle. In addition to the excavation itself, Dr David Johnson has conducted extensive historical research, and examined in detail the field walls at the site, to place the results into their wider historic context, which is detailed in the report available below and also intended for future publication. Finally David has recently given a talk on the results of the project for the Westmorland Dales webinar series.

Acknowledgements

Both Dr Johnson and I would like to extend our thanks to the owner John Bucknall and tenant Bob Akrigg for kindly accommodating and supporting the project. Thanks also goes to all of the fantastic volunteers who took part: Lunesdale Archaeology Society, Ingleborough Archaeology Group, Hannah Kingsbury (WDLP Cultural Heritage Officer), and Miles Johnson and Luke Bassnett Barker (YDNPA). Thanks must also go to Denise Druce (OAN, charcoal analysis), Jeremy Bradley and Barbara Blenkinship (ceramics analysis), Chris Howard-David (glass analysis) and SUERC (Scottish Universities Environmental Research Centre). Finally, thanks to all the attendees of our guided walks, as well as the many visitors to the castle that were given a site tour of the excavation.    

Bibliography

Blenkinship, B. 2020. Ceramics. In Johnson, D.S., with contributions by Blenkinship, B., Bradley, J., Hicks, J., Mitcham, D. and Worthington, T. 2020. Archaeological Investigation of a Sow Kiln at Pendragon Castle, Mallerstang, Cumbria. Unpublished report for Yorkshire Dales National Park Authority and the Westmorland Dales Landscape Partnership. 27-28.

Bradley, J. 2020. Medieval Pottery. In Johnson, D.S., with contributions by Blenkinship, B., Bradley, J., Hicks, J., Mitcham, D. and Worthington, T. 2020. Archaeological Investigation of a Sow Kiln at Pendragon Castle, Mallerstang, Cumbria. Unpublished report for Yorkshire Dales National Park Authority and the Westmorland Dales Landscape Partnership. 28-30.

Clark, G.T. 1883. On the Medieval defences of the English border. Transactions of the Cumberland and Westmorland Antiquarian and Archaeological Society Vol. 6: 38-49.

Curwen, J.F. 1913. The Castles and Fortified Towers of Cumberland, Westmorland, and Lancashire North-of-the-Sands. CWAAS Extra Series 13. Kendal: Titus Wilson.

Howard-Davis, C. 2020. Glass from Pendragon Castle. In Johnson, D.S., with contributions by Blenkinship, B., Bradley, J., Hicks, J., Mitcham, D. and Worthington, T. 2020. Archaeological Investigation of a Sow Kiln at Pendragon Castle, Mallerstang, Cumbria. Unpublished report for Yorkshire Dales National Park Authority and the Westmorland Dales Landscape Partnership. 26-27.

Johnson, D.S., with contributions by Blenkinship, B., Bradley, J., Hicks, J., Mitcham, D. and Worthington, T. 2020. Archaeological Investigation of a Sow Kiln at Pendragon Castle, Mallerstang, Cumbria. Unpublished report for Yorkshire Dales National Park Authority and the Westmorland Dales Landscape Partnership.

Whitaker, T.D. 1805. The History and Antiquities of the Deanery of Craven in the County of York. London: Nichol.