Clunch is a term for traditional building material used mainly in eastern England and Normandy. It is a term which encompasses a wide variety of materials, often locally variable.
It often comes as irregular lumps of rock either picked up from the fields, or quarried and hewn from the ground in more regular-shaped building blocks. It is predominantly chalk/clay based and is bedded in mortar to form walls. It is a particularly soft building material. Some people comment that it could be cut by a saw.[1]
The stone is a chalk from the Lower Chalk of the Cretaceous age, the period of geological time approximately 143-65 million years ago. It is a greyish white colour often with a greenish tinge. The latter is due to the presence of glauconite, the potassium and iron aluminium silicate mineral also found in Kentish Ragstone.[2] The stone has a gritty texture due to the frequent presence of shell fossils.
It is often a very soft limestone. It can be rich in iron-bearing clays or be very fine and white — in effect just chalk. It is used in various parts of East Anglia, where more durable stone is uncommon, and can be seen quite a lot in and around Thetford — mostly now for property boundary walls as it is not a long-lasting material, but it is also used for some building walls, especially in traditional agricultural buildings. In Ely Cathedral it can be seen in some interior locations. The nearby village of Burwell has a Parish magazine named after the building material.[3] It is found in the village of Seale in Surrey and in Farnham.[4]
The term is sometimes used more generically in other parts of England for any soft and aggregate-based vernacular building material which is used as a poor substitute for stone.