The tufa stone galleries
The cliffs of Bourré
The numbers are impressive: 580 km of galleries in the belly of the cliffs of Bourré, a small valley near Montrichard in the south of the Loir-et-Cher. The old quarries where tufa stone was extracted to build the châteaux are like castles themselves, hewn into the rock.
Known as the "stone of light" or the "stone of the kings," tufa is the emblematic mineral of the Loire valley. Châteaux, churches, abbeys, lodges, walls, bridges, monuments... for many centuries, any new building was made of this stone, dug from under the ground by quarrymen, called "Perriers."
The Cave des Roches
The Cave des Roches is the most notable example, a veritable underground city with towering facades. It contains 120 km of galleries, belonging to the Delalande family. The first traces of stone cutting date back to the eleventh century, and the last block was taken in 1920, due to the rising price of extraction.
The famous stone of "Bourré" is the most noble tufa stone, formed from marine sedimentation (organisms deposited at the bottom of the sea) and fragments of rocks brought by the rivers in the form of alluvium. These sediments bleached and hardened over time, taking 90 million years to attain their current form!
Life after the quarry
After extraction stopped, the constant temperature of the galleries (between 10 and 12 °) and the humidity of 80% made the galleries a perfect place for storing wine and growing mushrooms.
Button mushrooms, oyster mushrooms and even Japanese shiitake all grow in abundance in an underground city cut into the tufa by Christian Lhermite.
Lhermite carved the facades of famous buildings above ground into the underground cliffs between 1998 and 2001, in order to keep a copy of the architecture for posterity. Tufa is highly friable becoming damaged with time and bad weather, and especially air pollution.
