A large quarry at the north end of the Grwyne Fawr reservoir. The quarry area covered at least 200m north-south by 60m, and was associated with the construction of the reservoir in the early 20th century. Source: Rev DA Tipper in his 1975 book "Stones and Steam in the Black Mountains. The quarry was partially grassed over with trees growing on it in October 2007. J.J.Hall, Trysor, 10 December 2007