Moelwyn Slate Quarry

Moelwyn Slate Quarry is a quarry in Tanygrisiau, Wales, with seven inclines carved into the mountainside across multiple levels of the rock face. A processing mill at lower elevation between inclines 4 and 5 used water from Llyn Stwlan reservoir to power the slate cutting and finishing operations.

Initial exploration began in the 1820s, but the Great Moelwyn Slate Company only started formal operations in 1860, running intermittently until final closure in 1897. The construction of Ffestiniog Power Station in 1960 altered the site, removing sections of the seventh incline while leaving other structures intact.

Workers and their families lived in simple barracks on the site, with schooling for children beginning in the 1860s to provide basic education in this remote location. These facilities show how the quarry community was structured and the commitment to learning even in isolated working conditions.

The site sits at elevation in Tanygrisiau and requires sturdy footwear to explore the various levels and paths around the old working areas. Access is best in dry weather since the terrain becomes slippery when wet.

The water from Llyn Stwlan reservoir powered not only the quarry mill but also fed the Ffestiniog Power Station built in 1960, which partly reshaped the site. This water source connects the quarry's past to modern energy generation in the region.

Location: Gwynedd

GPS coordinates: 52.97880,-3.99500

Latest update: December 14, 2025 17:41