1. Features associated with early mining north of Jeffreyston, portrayed on OS County series (Pembroke. XXXV.9 1865), further, similar features occurring elsewhere about the village (see nprn 268020).
J.Wiles, RCAHMW, 21.04.2004

2. A complex of earthworks typical of the early anthracite industry in Pembrokeshire and documented as having operated from the sixteenth to nineteenth centuries. It includes opencasts, bell pits and subsidence features.
(Source: Collieries of Wales, RCAHMW)
B.A.Malaws, RCAHMW, 01 June 2011.