Above Brynglas, the line crosses the Cwm Pandy stream and enters a shallow cutting, climbing as it goes. The cutting ends at a road overbridge after which the line runs through open countryside as it starts to ascend the valley side on a ledge. After approximately it enters woodlands west of , climbing steadily, then curves to the south east and crosses the Dolgoch gorge on the Dolgoch viaduct, which carries the line above the Dolgoch ravine. Dolgoch station is immediately east of the viaduct, situated on a left-hand curve at above sea level, and is the main intermediate station on the line, being popular with tourists visiting the nearby falls. The railway continues in a north easterly direction, curving through the woods and climbing the valley side. It shortly passes Quarry Siding, where a halt and passing loop are located; this is the site of a small old shale quarry, the rock from which was used for ballasting on the railway. A large permanent way and storage shed opened on the site in 2013. The line continues its ascent towards Abergynolwyn station, situated on a ledge cut into the hillside.