THE discovery of a large medieval limekiln in Ripon has caused great excitement among local historians and archaeologists.
The circular structure, which is believed to be more than 500 years old, was unearthed behind Ripon House, on Residence Lane, by Leeds-based Archaeology Services WYAS – a company carrying out exploratory excavations as part of development work on a new housing project.
Project officer Phil Weston said: "As a piece of industrial history the kiln is quite an important find."
The remains of the excavated kiln consist of a 2.2 metre deep tapered pit measuring nearly six metres in diameter at the top and four metres wide at its stone-flagged base, making it one of the largest medieval lime kilns ever discovered in the UK.
Mr Weston said: "Generally, these kilns are around three metres in diameter but this is 5.7m-wide. I have read of only one other example which was bigger."
As shown in the pictures, the kiln has two opposing flues with stone lintels over their openings which would have been used to control how much air entered the structure.
The kiln would have been used for burning limestone to make quicklime, a product that can be used in agriculture and for making mortar.
Mr Weston said: "Given the fact it is close to the historic town, the kiln is likely to have been involved with medieval building projects."
Pottery recovered from the kiln dates its abandonment to the mid-16th century but Mr Weston said it was difficult to establish how long it had been in use – he guessed it was around 50 years.
Dr David Rivers, of Ripon Community Archaeology Project, said one possible use for the kiln was in the re-building of Ripon Cathedral's central tower which took place in the late-15th century following its collapse in 1454, as well as expansion works relating to the nave and side-aisles which were completed in the 1500s.
"The work at the cathedral is one thing we know did take place around the time the kiln was in use that would have needed lime mortar," he said.
Archaeological interest in the site at Ripon House was generated by 18th and 19th century records which indicate it is the possible location of a seventh century monastery. Previous finds in the area have included old walls, sculpted stones and ninth century Anglo-Saxon coins.
Mr Weston said other finds from the kiln include masonry, ceramic tiles, decorated window glass and a selection of lead and iron roof fittings. A small amount of animal and human bone was also recovered.
He said: "Although no definite evidence of any monastic buildings was found, the kiln's in-fill seems to represent a sample of residual material possibly associated with earlier medieval uses of the site, the glass being typically ecclesiastical and the human remains possibly originating from a disturbed nearby burial ground."
Further archaeological investigations are expected to be carried out at the site in the summer after the Ripon House building has been demolished.