The Slate Landscape of Northwest Wales

Slate from northwest Wales was used in Roman times, on the roofs of the fort of Segontium at Caernarfon. The first record of quarrying near the later Penrhyn Quarry dates from 1413, when tenants were paid for working 5,000 slates. Until the late 18th century slate was dug by small local partnerships who paid a royalty to the landowner.

From the late 18th century landowners began quarrying on a large scale themselves, and after the slate duty was abolished in 1831 narrow-gauge railways were built to carry slate to the ports. Penrhyn and Dinorwic became the largest slate quarries in the world, and the Oakeley mine at Blaenau Ffestiniog the largest slate mine. By the late 19th century the region produced about a third of the world's roofing slate; in 1898, 17,000 men produced half a million tons.

A bitter dispute at Penrhyn from 1900 to 1903 marked the start of decline, and most of the large quarries closed in the 1960s and 1970s. Skills and workers from the region carried the industry to the United States and continental Europe, and its narrow-gauge railways became models for lines around the world. The landscape was inscribed in 2021.