Underground workings into side of cliff on 6 levels. Various remains including cut & cover tunnel.***

The ruins of the quarry are spread across the six levels of the scarp. A general working area includes a small building and a chamber accessed via a cut-and-cover tunnel.

• Level 2 shows evidence of only a tiny, non-productive working.
• Level 3 consists of a twisting strike tunnel that leads into pillared chambering, which provides a connection up to Level 4.
• Level 4 is extensively chambered for approximately 300 feet. Notably, it still retains footboards for a roofing tunnel and features a small underground forge.
• Level 5, chambered from Level 4, has surface remains including the circular base of a powder house with an adjacent rock bench, and evidence of a possible slideway down to Level 4.
• Level 6 features traces of small buildings and was chambered from the workings below.

On the surface, structures include dressing sheds, a small smithy, and the remains of a remote-type drum house situated at the head of the incline. All the surviving buildings on the site are noted to be in poor condition.

Clogwyn y Fuwch was a fully unmechanised underground quarry, likely dating back to the 18th century. It operated across six levels, rising about 400 feet up a near-vertical rock face. In its early years, slate was hauled down the incline on sleds, with a more organized table incline introduced around the 1820s. Despite the quarry’s difficult terrain and the fragile nature of its small slates, work continued until unexpectedly late. Records from 1890 show that a crew of just three men, led by O.E. Hughes, produced 155 tons of slate. The quarry eventually ceased operations in the early 1900s. Most of its output was used locally, although Trefriw served as a possible shipping point for export.