Mynydd Gartheiniog is a mountain in southern Snowdonia, Wales. It is a long ridge running south from the cliff of Craig Portas above Dinas Mawddwy and parallel to Mynydd Dolgoed which lies to the west.

Mynydd Gartheiniog
The slopes of Mynydd Gartheiniog, looking east towards the Dyfi valley
Highest point
Elevation	640 m (2,100 ft)[1]
Naming
Language of name	Welsh
Geography
Location	Gwynedd, UK
Parent range	Snowdonia

The Gartheiniog slate quarry sits on its eastern flank, and was served by the Hendre-Ddu Tramway.[2]

It is one of the Dyfi hills.

References