To the East of the twll is a finger tip of waste and scant remains of a caban/waliau. The original shallow access incline provides easy access to the twll itself where there is a lot of loose waste rock and the entrance to an adit. This is flooded and leads to a collapse. The other end of this is also blocked but can be seen below the Rhiwbach Tramway to the North.

There are references to slate from Blaen-y-cwm Farm, Penmachno but it isn’t known exactly where these were.
It is more certain that that this is one of the earliest recognisable slate quarries that make up what is now known as Blaen-y-cwm. Slate was taken out via carts up a gentle slope to the West. This initial period of working around 1818 was almost certainly very short.
It was however worked again later, via a tunnel, after the Rhiwbach Tramway tramway had been built. At ths time the slate was most likley taken out via the internal tramway, down Watson’s incline, through another tunnel and into the main mill as the earlier Gatty’s Mill had been removed.

CROW. Open