Pwerwyd y Chwyldro Diwydiannol gan lo o gymoedd y De, ond llechi oedd ar doeau cartrefi'r bobl a'r ffatrïoedd lle roeddent yn gweithio. Cloddiwyd y llechi hyn gan ddynion gweithgar a medrus bro’r chwareli.
The Industrial Revolution was powered by coal from the South Wales Valleys, but the homes people lived in and the factories where they worked were covered with slate, which was quarried by hard-working and skilled men in the mountains of Northwest Wales.