Engine house (?) associated with shaft at Nantle Vale Slate Quarry (Nprn400633), shown in-use on OS County series 1st ed. (Caernarvon. XXI.9 1889), but not subsequently (1900, 1916); by 1916 site falls within area of Ty Mawr E Slate Quarry (Nprn400634).
RCAHMW AP945127/49-50
J.Wiles 16.06.04