The Cob, (partly in Penrhyndeudraeth)

A substantial rubble-built embankment approximately 1.5 km long, consisting of a lower (road) section and a higher (rail) section. The higher part of the embankment is approximately 6m tall with single-track railway and flanking footpath. The later and much lower 1836 embankment has a narrow double carriageway. The seaward (S) side is heavily buttressed by boulders gradually sloping down to the water. The buttressing on the (N) landward side is less substantial and is predominantly a grassed bank. Parapets are of rubble slate-stone, approximately 0.5m to 1m high (except to the seaward side where it is concrete). The parapet between roadway and cycle track is of stone from Dyffryn Nantlle, replacing a wall of stone from Blaenau Ffestiniog. Masonry breaks and changes in the coping indicated that the wall between the higher and lower sections has been heavily repaired. At the Porthmadog end the parapet of the higher embankment terminates opposite No 6 Tros Y Bont and beside the curve into the railway station. On both sides of the higher embankment at the E end are steps down to the shore and the road. Beyond, the railway tracks curve NE or continue into the Boston Lodge Workshops. Beneath the curve is a semicircular arched recess, now blocked but originally serving as a passage beneath the railway. It has a portal-like entrance with coursed masonry and voussoirs. At the Boston Lodge end the Cob terminates at the gated steps between the railway line and the road.