After leaving Beddgelert Station trains heading north on the Welsh Highland Railway (nprn 91420) followed what appears to be a somewhat devious route on the map but which in effect was designed to gain height whilst avoiding a steep gradient. The course of this loop survives at a point near to the farm of Cwm Cloch Isaf. Most of the course is still visible where it cuts through the area and the concrete stanchions of the river and road crossings survive. A substantial embankment remains at the S part of the loop where the track is up to 12m above the surrounding land for a distance of 130m. The embankment was built out of the waste from nearby quarries. The average width of the trackbed is about 2m. There are no surviving iron structures or track.
This observation made in 1987 since when the track has been reinstated. The railway was officialy first opened on June 1st 1922 joining two pre-existing lengths of slate carrying tramways. It continued until 1937 but the track was requisitioned for scrap during WW2, before being finally wound-up in 1944.

John Latham, RCAHMW, 23 Aug 2011.