It used to be said with some pride that Delabole slate quarry was so big it could be seen from space. Nowadays, given the state of satellite surveillance technology, that’s not saying much. But it’s still a big hole in the ground by any standards – the largest open work in a region where open workings for granite, china clay and tin are not exactly rare.
The pit at Delabole is over 425 feet, or 130 metres, deep and a mile and a half in circumference. Slate has been quarried there from at least the mid-1200s. Over the centuries a number of separate small quarries gradually linked up and eventually the Old Delabole Slate Company brought these together in one concern in the 1840s. This was a decade when granite quarries were also being opened up in Cornwall. Incidentally, unlike the mining industry but like the granite quarries, this company was at first owned by a group of non-Cornish investors – from Plymouth.
The quarry would have been a hive of industry in the mid-1800s. At that time, it employed around 700 people, a quarter of them boys, and including 70 women. Most of the women drove the donkeys that carried the slate away from the quarry edge, but some were employed as splitters. This was a very skilled task, splitting the blocks of slate that had been blasted out of the rock face by the rockmen. After the 1850s, women were not employed.
In 1913 there were still over 400 men working at Delabole, although numbers shrank over the course of the twentieth century. Growing competition from cheaper roofing materials could not all be offset by new uses for associated products. Slate waste was used to produce concrete blocks while a filler from slate powder became an important element in the booming production of gramophone records from the 1930s.
That market disappeared in the 1960s. By 1958 the workforce had fallen to 150 and a series of redundancies then reduced this figure to around 60 by 1975. Nonetheless, the quarry still produces a variety of quality slate products.
For more detail, see the history of Delabole and its slate quarry by Catherine Lorigan, Delabole: the history of the slate quarry and the making of its village community, Reading, 2007.