I'm planning a visit to the WW1 sites and my route takes us through Lens/Sallaumines (where Europe's worst mine disaster took place in 1906 at Courrieres). As there could be some interesting surface remnants to visit I searched on line for info and came upon this:
http://fresques.ina.fr/memoires-de-mines/geolocalisation The clips are a great record of events good and bad in the region immortalised by Emile Zola in his book (and film) "Germinal". It is in French but the terminology soon becomes clear. A fosse is a shaft, puits are pits, chevalements are headstocks and terrils are tips, some of which are still in existence. There are some excellent films showing underground scenes from the 50's and the same social upheaval and deprivation as the UK with closures during the 70;s, 80's and 90's