The Touraine has large deposits of limestone across the region. This is highly visible in its use of light tuffeau stone used in so many local buildings such as the one at Chêdigny, left.
Below is a map from 1948 showing the sites of Fours à chaud or Lime Kilns and their spread across the Touraine. A lime kiln is an insulated chamber or oven used to produce quicklime through the calcination of limestone. It is a process that has been used for many hundreds of yeas to produce lime to use in mortars and as a stabilising agent in mud rendering and floors. It also has long history of agricultural use as a means of increasing pH levels in acidic soils and improving the uptake of plant nutrients such as Nitrogen. Take a look at the Fours à chaud marked as:…..it’s also an interesting sketch map for other reasons, enjoy: