Holme Bank Chert Mine - Alan Brentnall
After my brief interlude in Mallorca, I was pleasantly surprised to find that a trip into Holme Bank had been organised by Alan Walker for tonight. It's quite a while since any of us have been to this particular mine, and there were a few amongst us for whom it was a first trip, so it was no surprise that the trip was popular - with no less than twelve joining in. Unlocking the entrance gate, we headed first for the dive base before venturing further into the mine and even, at one point, testing the still working rolling stock - and a nearby cable winch.
Holme Bank was, up until the 1960s, a mine providing large lumps of chert for the slip mills of the potteries, until Eastern European countries were found to produce the material at a lower cost. Chert, like flint, is silica - a very hard substance which is thought to derive from beds of silicate sponges which were laid down in the same period as the limestone. As well as providing the grinding tool in the slip mills, it was also used as a building material (look at some of the older houses in Bakewell) and, latterly, as a test bed for drill bits! The method of extraction of this hard material involved removing the limestone from beneath the chert layer, and allowing the heavy chert to break off in blocks. This was done in a "pillar and stall" fashion, and packwalls were also used to support the roof as the mining face advanced, and this has produced quite a maze of fairly large passages which require some careful navigation. Holme Bank is a good place to practise your survey reading skills.
With such roomy passages, it is very easy caving, and Holme Bank is popular with Outdoor Centres. But there are hidden dangers, as the huge roof is forever pressing down on the packwalls, and there is evidence of some quite severe bulging and even collapses. Because of this, "tell tales" (wooden pegs jammed into roof cracks which will indicate movement) abound, and, because some people (instructors) still earn a living in the mine, it has, by law, to be regularly inspected on behalf of HM Mine Inspectorate. These inspections are organised and paid for by PICA, an organisation comprising local outdoor centres and freelance instructors and cave leaders. The last such inspection was done by Les Riley in 2013, when he recommended that a certain passage in the mine should cease to be used, because of the state of the roof and packwalls. It was the annotated survey produced for PICA by Les in 2013 which we were using last night to guide our route.
So, an easy but very interesting trip last night, covering most of the regularly used passageways, and giving a good insight into an industry which is no longer with us. This was followed by a pleasant chat over a beer in The Castle in Bakewell.