The open pit and underground workings have remain flooded since the mine closed in the 1970s.
The coalmine, unlike those in other regions, also had underground workings.
In 1900, a large section of the underground workings collapsed, in what was known as the "great fall".
The technique was very dangerous in underground workings without adequate ventilation.
The underground workings themselves are of great speleological and historical interest.
In 1917 a major fire caused extensive damage including the underground workings.
It had not surprised me, therefore, to find the underground workings of an old mine being used in this way.
By 1840 underground working had begun and a large steam-driven cutting mill was opened around 1860.
Another source of contamination was water leaking from older underground workings.
However, profits were tempered by the temperature of the underground workings.