The vein which Moelwyn worked continued dipping to the west, and the Pant-Mawr quarry worked it lower down. In order to prevent the collapse of the Moelwyn workings, the Pant-Mawr chambers were located beneath Moelwyn chambers, and there were some connections between the two quarries to ensure that this was the case. In addition, the Pant-Mawr chambers were numbered sequentially with those of the Moelwyn Quarry. Finished slates were initially transported to the Ffestiniog Railway at Penrhyndeudraeth by pack animals, using Moelwyn's traditional route, but subsequently, two inclines were built to connect to the Croesor Tramway.