 It was built in 1872, partly as a conversion of the earlier Gorseddau Tramway, which in itself had incorporated the even earlier gauge Tremadoc Tramway.It opened to mineral and goods traffic in 1875.The main line followed the route of the original Gorseddau Tramway from Porthmadog through Tremadoc, "Penmorfa" and "Ynys-y-Pandy" to Gorseddau quarry.