A section of the short-lived but invaluable Elan Valley Railway, which was built to carry construction material used for the remarkable Birmingham Corporation water-works scheme of dams and reservoirs. This photograph shows the locomotive 'Elan' hauling a ballast train southwards down the valley between the sites of the Pen-y-Gareg and Careg-ddu dams, just across the river from the mansion of Cwm Elan. The valley below the track was later to be submerged as the dams were completed.