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Phil Raynes wrote:For those who might be interested, the following two links will take you to a couple of sites where spelunkers have been exploring Welsh Slate mines once served by the Welsh Highland Rwy. These mines were closed in the late 1930's, but used during WW2 for storage of High Explosives. They were very deep in areas, up to 240' or more deep, with bridges (wood or steel) across the opening where different levels needed to cross. Since many of these bridges are collapsing, travel through them is highly dangerous - but from what the reports say, highly exhilerating! However, I don't think I will be trying it any time soon! These two mines actually had a connecting shaft, which improved ventilation. However, they have been filling with water, so the lower levels are inaccessible (unless you are a SCUBA diver, I suppose!).
While these mines are normally off limits, Blaenau Ffestiniog does have a mine open for tourists, and can be visited when visiting the Ffestiniog Rwy.
http://www.mine-explorer.co.uk/mines/Croesor_195/Croesor.asp
http://www.mine-explorer.co.uk/mines/Rhosydd_539/Rhosydd.asp
Phil
jlancasterd replied:Croesor was also used as an explosives store for many years after WW2. The explosives came from the Cookes Explosives factory (latterly part of ICI) in Penrhryndeudraeth, close to the Ffestiniog Railway.
There was a major panic (in the late 1970s?) after the Tanygrisiau pumped storage power station had been built - the upper dam is sited on the opposite side of the mountain from Croesor. The authorities suddenly 'discovered' that Croesor contained hundreds of tons of explosive, some of in delicate condition, and went headless chicken about what would happen if it exploded... The upper dam was drained and the power station taken off-grid whilst the explosives were removed and destroyed.
John Dobson
