Rottenstone has been extensively worked in South Wales along the outcrop of the Carboniferous Limestone, particularly within the Brecon Beacons National Park. It occurs at the top of the sequence where the Upper Limestone Shales have been weathered. Innumerable workings were initiated and later abandoned during the course of the nineteenth century, leaving a characteristic terrain of humps and hollows. A notable example is that on the flanks of Cribarth exploited by industrial entrepreneur John Christie.