(Previously published in The Countryman, January 2010).
An interesting man-made feature of the landscape of South Cambridgeshire is the cluster of clunch pits dug into the sides of the low chalk ridges bordering the upper Cam valley and along the Fen edge towards the Suffolk border. These quarries were hewn by hand from the chalk outcrops. The extracted ‘clunch’ was used as a building material from medieval times up to the end of the Nineteenth century. ‘Clunch’ is in fact the traditional local term for a hardened chalk, a band of white cretaceous limestone found in the Lower Chalk, known as Totternhoe Stone, after the quarry of that place in Bedfordshire, where the seam is at its thickest and was originally quarried by the Romans. This band of hardened chalk was formed when the tropical sea that covered these parts in the Cretaceous period was reduced to a channel, some nine metres deep, between Buckinghamshire and south Norfolk. The channel filled with chalky material from higher ground, which became compacted and then chemically altered by the cementing of the silica to produce its relative hardness.
Today it forms a distinctive band out-cropping in the Chiltern Hills from Buckinghamshire in the west through to south east Cambridgeshire. Being underlain by the impermeable marly chalk it forms an acquifer. Water percolates down from the upper chalk levels to the Totternhoe Stone to emerge as hillside springs. Consequently, as a dual source of fresh water and building material the outcropping of Totternhoe Stone, or clunch, was an important determinant in the location of village settlements.
In South Cambridgeshire a cluster of these clunch pits occur on either side of the low chalk elevation that borders the Wimpole (NT) estate, continuing across the A603 to finish above Haslingfield. This ridge is the route of the ancient track known as the Mare Way. On either side of the ridge there are quarries or ‘pits’ near the villages of Eversden, Orwell (see photo), Harlton, Barrington (now a cement works recently closed) and Haslingfield. Chalk outcrops on the other side of the upper Cam valley, for example near Foxton and Newton, also show the remains of old pits. The largest clunch pits lie in an arc from Cherry Hinton on the south eastern outskirts of Cambridge through Reach, Burwell and Isleham, the furthest point east in the county. The latter three ‘fen edge’ pits were connected by canals or lodes to the fen waterway system, enabling large quantities of clunch to be supplied to more distant markets, including Ely (for the building of the cathedral) and King’s Lynn.
In medieval times clunch was widely used as a building material in the county, despite its porosity and susceptibility to weathering, because of its ready availability and the absence of local sources of stronger building stone. This continued to be the case until the late nineteenth century and the wider adoption of clay bricks using the local Gault clay, with its distinctive yellow-grey colour.
From the twelth century clunch was widely used as a building material in the construction of local churches. Being suitable for fine carving the clunch was much valued for decorative work in church interiors. The best examples of this use can be seen in Lady Chapel in Ely Cathedral and St. John’s College Chapel in Cambridge. Clunch was also used for structural work in church columns and arches, for example the chancel arch and the panelled ceiling of the tower room in St. Mary the Great in Cambridge. It was also used for external walls.
The freshly quarried clunch (see photo) was capable of being cut or hewn by hand into masonry blocks (ashlar) with squared edges and even faces, allowing it to be laid in regular courses with fine joints of lime mortar. Once dry the clunch turns from grey to almost completely white. It also becomes brittle and cannot be worked without shattering. Traditionally, the external surface of the clunch ashlar was protected from the elements with a coat of lime wash, renewed at intervals. The parish churches of Eversden, Harlton, Barrington and Haslingfield all used clunch from local pits in this manner as well as clunch rubble as a ‘core’ material with lime mortar.
What of secular buildings? Clunch masonry was widely used in the initial building of the medieval Cambridge colleges as a facing material with clunch rubble behind. Cauis, Trinity and Queen’s college records show large quantities of clunch taken from the pits at Barrington, Haslingfield, Cherry Hinton, Reach and Burwell. Later, clunch was superseded by brick as the main building material.
Clunch was not widely used as a primary building material in medieval village houses, which were typically timber-framed with wattle and daub and lime wash plastering. However clunch was used for footings, chimneys, small outbuildings such as granaries and brew houses, and boundary walls. There are a few instances of the partial use of clunch ashlar in larger timber framed or brick buildings. Church farm in Barrington is a good example. Interestingly, clunch ashlar was more widely used as a primary building material in the early to mid nineteenth century; examples being Church House in Gt. Eversden and some small dwellings in Harlton and Haslingfield.
(Reader’s seeking more information on the use of clunch in local buildings should consult the ‘Inventory of the Royal Commission on Historical Monuments for West Cambridgeshire,’ (Royston Library), which provides a detailed survey. Information is also provided by the relevant volume of Pevsner on the buildings of the county).
The adoption of brick as the main building material by the second half of the nineteenth century led to the gradual disuse of the clunch pits, which have slowly been reclaimed by nature; their edges now softened by trees and hedgerows of blackthorne and elder. They remain important today as a wildlife habitat and for the open spaces they provide for local villagers and walkers. The footpath from the village hall car park in Orwell up to the top of the clunch pit affords a fine view of the Rhee or upper Cam valley across to the high ground on the far side, upon whose lower slopes runs the prehistoric Icknield Way (see photo). Similarly the pit at Harlton forms part of a pleasant circular walk from the village up onto the Mare Way. The clunch pit itself has a dense covering of trees and is now a place of tranquillity and some beauty (see photo). Several of these pits have been designated ‘Sites of Special Scientific Interest’ including Orwell pit, noted for its rich chalk grassland flora, a habitat now scarce in Eastern England. More than this, the pits are a reminder of times past, the product of physical labour by generations of local people over the centuries. As such they should be valued as an important part of the archaeological record of human activity for the past millennia.