In order to provide an outlet for slate from Fron Boeth Mill (NPRN 408879), a 450 metre-long tunnel was cut through thr ridge separating the quarry from Cwm Croesor. The 1st edition of the 25-inch O. S. map, 1889, shows the tunnel under conbstruction from the south-east end. Slate was hauled by horses through the tunnel and along a contour tramway to the head of the lower pitch of the inclines from Pant Mawr Quarry (NPRN 408873). The incline (NPRN 408878) had to be extended at its head by some 40 metres, and a new drum house built, to connect with the new tramway. The 3rd edition of 1919 shows the quarry as disused, though the tramway appears to be still in place. A small building adjacent to the south-east portal may have been a dressing area for Cefn y Braich Quarry (NPRN 408884).
W J Crompton, RCAHMW, 1 April 2009.