 The nearby Marchlyn quarry was opened in the 1930s to provide access to the main slate vein higher up the mountain.The quarry closed in July 1969, the result of industry decline and difficult slate removal.During the 1950s/60s extraction had become difficult, because after 170 years of extraction many of the unsystematically dumped tips were beginning to slide into some of the major pit workings, and after an enormous fall in the Garret area of the quarry in 1966, production had ceased almost permanently.