Stone as a local resource
Much of what people notice when they walk through a Cornish village is stone. Walls, chapels, bridges, farmhouses, quays and gateposts are often made from rock that was dug or gathered within a few miles. Before good roads and railways, moving heavy building material was expensive, so builders generally used what lay close at hand, and the result is a strong local character that varies from district to district.
Two rocks stand out in this story: granite and slate. They behave very differently, which is why they were used differently.
Granite
Granite is a hard, coarse-grained igneous rock that forms large masses underground. In Cornwall, several of these masses have been exposed at the surface and form the high ground of the moors and some western headlands. Their weathered outcrops are the tors that dominate such places as Bodmin Moor. The same granite gave rise to the metal-bearing zones around its edges and to the china clay that is worked in the St Austell area.
Because granite is very durable, it makes excellent building stone, but it is also hard to cut, and that shaped its history in several ways:
- Moorstone. Before large-scale quarrying, builders used loose surface boulders called moorstone. These could be split by hand using wedges, a method that left characteristic marks in old stone.
- Quarried granite. In the nineteenth century, quarrying expanded as transport improved and better tools and techniques became available. Large blocks could be cut for engineering works, public buildings and monuments, and in some cases shipped away from the county.
- Finishing. Cut granite can be dressed to a fairly smooth face by skilled masons, though carving fine detail is laborious. This is why granite buildings are often plain and solid in appearance.
Granite shows up in many places, from the simple granite cottages of upland villages to chapels, farmhouses and gate stoops. Large cut stones were also used in harbors and sea defenses, where strength matters. A well-built granite wall can last for centuries, though salt and weather slowly wear any stone.
Slate
Slate is a fine-grained rock that splits into thin, flat sheets, which makes it suitable for roofing, floors, window sills and monuments. Cornwall has slate-bearing rocks in several areas, and the quarry at Delabole in north Cornwall is the best known. Slate was cut, split and trimmed by hand into roofing pieces, with different sizes and grades. Workers who split slate developed special skills for reading the grain of the rock.
Slate has a role beyond roofs. Thin slabs were set on edge to form field boundaries in some districts, used as gravestones, and cut for house steps and flagstones. Its dark, slightly blue-gray look is common in the north of the county. Because slate is lightweight compared with thick granite blocks, it could also be transported more easily.
The workforce and working conditions
Quarry work was heavy and dangerous. Before modern equipment, men used hand tools, wedges, drills and black powder. Falls of rock, accidents with explosives and dust-related illness were hazards. Quarry workers were often neighbors of miners and farmers, and some men moved between these trades or worked a smallholding alongside, though the detail depended on time and place. Records of numbers and wages exist in places but vary, and it is best to avoid quoting exact figures without a source.
Some quarries built their own transport links, such as tramways down to quays or railways, to move stone to ports. Where harbors were built or improved, stone for the walls often came from nearby, which ties quarrying to the history of harbor design.
Reading a building
A few general clues can help interpret what you see:
- Large, rough or roughly squared blocks with thick mortar joints often indicate local moorstone or field stone.
- Neat, finely dressed granite suggests later work or a more expensive building.
- Slate roofs, slate-hung walls (where slates are fixed on the outside of a wall as protection from weather) and slate sills are typical of areas where the rock is local.
- Mixed walls, with granite quoins at corners and rubble stone between, are common.
Not every stone building in Cornwall is made of granite or slate. Other local stones, such as various sandstones and greenstones, were used in different districts, and later buildings often used brick or imported materials. Care is needed when generalizing.
Decline and reuse
Many small quarries closed as demand fell, competition grew and cheaper materials became available. The pits left behind are now often flooded or overgrown and may be important for wildlife. Some are used for recreation or as sites for study, and a few remain in production. Old quarries can be dangerous, with sheer drops, deep cold water and unstable edges, so they should never be entered casually. The same caution that applies to mine site safety applies to them.
Stone-built heritage also needs ongoing care. Repairs generally work best when they use matching local material and traditional methods, a point often raised by conservation specialists. Anyone interested in the use of stone is best served by looking carefully at the buildings themselves, with respect for the people who live and work in them.