This is my first-ever blog. I hope somebody sees it. It follows one-to-one meetings with two ex-ICI men, both now retired, one of whom is a civil engineer who studied subsidence in detail over a long period and is regarded as particularly knowledgable about it. Their information overlapped and so this is a combined report following both interviews.
I got a lot of detailed information and I am uncertain as to how much of it I should put here, especially as you probably know a lot from other sources
. Anyway, here goes.There are two layers of salt under Northwich (top bed and bottom bed), so perhaps Emma could fall to one level and then fall further. If she were to fall down the shaft all she would see would be the brick lining (and if not a brick lining it would be wood). If she were to fall into a big hole (not the shaft) and go all the way down, which would not happen in real life, she would pass first through about 22 metres of glacial marl (general detritus deposited there by glaciers) and then through black mudstone to about 42 metres below the surface. This would bring her to the top of the top bed of salt, the Wet Rock Head. It was at this level that water which had permeated down from the surface started to dissolve the salt, creating wild brine. Companies then pumped this out which resulted in more water coming in. The instability caused by the constant flow of water caused a lot of the subsidence.If Emma then fell to the floor of the top salt bed she would then be about 71 metres below the surface and there she would find a lot of small domed caverns. From about the 1750s shafts were sunk to this level and salt was cut from around each shaft. The resulting caverns were numerous, small and soon abandoned, unsupported to begin with. Later some were supported but the pillars were not thick enough and when water got in it dissolved the supporting pillars of salt and caused some of the subsidence.Below this bed is a layer of marl, claylike and probably grey but not always. Below this again is the bottom bed of salt, the floor of which is about 97 metres below the surface and with a ceiling of about 8 metres. The supporting pillars of salt again were not thick enough and collapsed after erosion through being dissolved in water. More subsidence. One solution was to pump in saturated brine so that no more salt would be dissolved. However, some owners pumped out the saturated brine in order to sell it and so precipitated more mine collapses.I have in my mind a pantomime villain Victorian mine owner rubbing his hands and ordering the saturated brine to be pumped out knowing that it will result in a collapse and subsidence at the surface.At Winsford they left much thicker pillars. There they took only 70-75% of the salt whereas at Northwich they took up to 95%. Hence no mine collapses at Winsford.It strikes me that water is central to all of this. So, while we don't want to drown any children, perhaps water/boats could be the way Emma gets down to Underwych and moves around while she is there, from chamber to chamber. There was a canal collapse, caused by subsidence, at Marston (lost the date for the moment but I believe it's well known) and boats were washed into the breach. Perhaps Emma could be on a boat which goes with a a rush of water over the newly created edge and down into Underwych. Would it be possible to simulate something like that? (Sorry Caroline, canals again.) In any case, even if Emma simply falls down a hole she would probably see water bursting through the walls of earth as she fell. Also miners sometimes drilled through from a dry mine to a wet mine in order to get brine into the dry mine. In other words there are horizontal shafts for Emma to move through, too.During the nineteenth century dinner parties were given down salt mines, presumably at the bottom bed where there was most space and headroom. Guests went down in the miners' cage.(Another possibility for Emma.) It is believed that on one occasion the Russian ambassador attended. Another possibly useful fact is that donkeys were used underground, and kept in underground stables, until about 1920. Another mode of transport!According to my information most of the earliest chamber mines (spheres) were under the town. These were in the top bed, from about the 1750s. The first subsidence occurred in about 1770. The last collapse (Adelaide mine) was in 1928. Buildings were often on jacks, as I think is well known, but a canal bridge at Marston was actually raised on jacks.I have more but I think you have suffered enough for the moment .
I should welcome advice on copyright law from anyone who knows. Where do I stand if I put a quote from a book on this blog?
I have looked at the preview and it seems that the font size changed for some reason after the first few lines. Anyway it makes it easier to read.
More bits and pieces to follow.
Arthur Williams
Labels: creative writing, Northwich, subsidence
Hello everyone,