A recent excavation of a suspected sow kiln at Pendragon Castle, Mallerstang, was an exciting start to the Westmorland Dales Landscape Partnership’s Monuments at Risk project. Dr David Johnson led the excavation with a total of 14 volunteers during the first two weeks of September. 


Pictured: Pendragon Castle excavation site

So what is a sow kiln? Sow (or clamp or sod) kilns date from the Anglo-Saxon period (450-1066) and remained in use until the 19th century. These kilns converted limestone into quick lime for lime mortar. The earthwork consists of a curving bank which is penannular in shape. The bank is roughly circular, with an opening at the front. This opening would have been closed by large stone lintels when the sow kiln was in use, removed after abandonment to be recycled as building material.

The sow kiln at Pendragon Castle is on the larger size for this type of kiln and as such was clearly designed for a major building project. It would have taken about a week to 10 days for each episode of lime burning, with a capacity of about 17m3 of stone and fuel. Within the bowl of the kiln the fuel (at Pendragon they were mainly using carbonaceous shale and coal) was layered with the limestone until a flattened dome level with the banks. This was then sealed with turves. Once finished they dismantled the kiln by taking the turves off, the lime out, and cleaning the bowl. It would then have been used again, for the number of times needed to complete the job. 

Before the excavation started the working hypothesis was that the kiln most likely dated to the Lady Anne Clifford restoration in the 1660s, due to its size and preservation. However, the construction of the banks was “cruder” than expected and may point to an earlier date. It could have been connected to building phases of the 14th or 15th century or even the castle’s construction in the late 12th century.

During the course of the excavation a number of finds were recovered.  These have been sent to experts to be analysed. They will hopefully be able to provide dates for the kiln’s use and will help to add to our understanding of the site.

Would you like to help us uncover more about a beautiful area of upland landscape in the Westmorland Dales? We are currently running Season One of the Great Asby Archaeology Survey on weekdays from Monday 23rd September until Friday 11th October (15 days in total). More information is available at this link