6 - Eyri ( Snowdon National Park ) - Misc
Cwmorthin Quarry
View of Cwmorthin Quarry from Foel Ddu
Quarrying began around 1810, and the site evolved into a massive underground mine with five levels and 60 miles of passages.
It was connected to the Ffestiniog Railway to transport slate and was eventually acquired by Oakeley Quarry in 1900.
The Cwmorthin slate waste tips extend fan like out into the lake - Llyn Cwmorthin.
-----------------------------------
Foel Ddu is to the north of Moel-yr-hydd (648m) - a child summit of Moelwyn Mawr (770m).
A steep hill walk to Foel Ddu with boggy moorland in places.
Ref: NW 4866
Date: 22/10/2025
Location: SH 6702 4585
