The collieries listed here are chiefly those mentioned in Hunt's "Mineral Statistics" and the "List of Mines". Two problems arise when using these sources:-
i) It is often unclear exactly where a mine was situated. Since the intention in compiling these tables was, wherever possible, to list the parish in which the pit lay rather than the general area, many have no location given, although their approximate positions may be obvious from their names.
ii) Although some dates of closure are given, it is often uncertain whether these represent the date on which the pit stopped working or the date on which it was abandoned.
Due to changes of name, re-openings, etc, it is likely that some pits are listed here more than once.