Carpenters Wood – Chalk Pits

Chalk is a soft white limestone made up of incredibly tiny calcareous shells – these are the remains of plankton that lived in massive abundance in the warm tropical seas that flowed over what is now Britain between 95 and 65 million years ago, during a period geologists call the Upper Cretaceous.

Chalk has been used by people for many reasons – some of them rather surprising, such as adding to foods for bulk and for whitening in toothpaste. The sort of chalk in this part of the Chilterns is occasionally suitable for building; chalk ‘clunch’ can be seen in some older buildings, and a special type of chalk in the northern parts of the Chilterns, called ‘Totternhoe Rag’, was even quarried to build parts of Windsor Castle!

The large chalk pits in front of you were a product of 19th and early 20th century industry. The extraction process would have initially involved hand tools, such as picks and shovels, before mechanised processes took over in the late 19th century. The chalk would have been dug out and transported, often by horse-drawn wagons, to nearby markets or processing facilities.

The uses for the extracted chalk were varied. In agriculture, lime was widely used as a soil conditioner, particularly in arable farming, to neutralise acidic soils and improve crop yields. For building, chalk was used both in its raw form for mortar and as a key ingredient in the production of lime, which was in turn used in construction and as a binder in bricks and other materials. By the early 20th century, as demand for cement rose, the use of chalk for this purpose became more pronounced, and local ‘smaller scale’ sites like this were abandoned in favour of places where massive scale operations could be conducted, such as the Chinnor Quarries.