THE LEAD MINES OF THE ALYN VALLEY By C. J. WILLIAMS The river Alyn, after rising a few miles south of Llandegla, flows in a northerly direction to Loggerheads, on the boundary of the former counties of Denbigh and Flint. Here it enters a narrow valley with steep limestone cliffs on its eastern side. Near Cilcain the river turns across the limestone outcrop and flows through a gorge to Rhydymwyn, and again turns sharply to follow a south-eastward course to Mold. Between Loggerheads and Rhydymwyn, in the Carboniferous Limestone on the eastern' side of the river in the manor and parish of Mold, are some half dozen major mineral veins, running roughly from west to east, from which great quantities of lead ore have been extracted over the last three centuries. From the late seventeenth century onwards, travellers have commented on the fact that downstream of Loggerheads the bed of the river is dry during the summer months,1 for the limestone is extensively fractured and water sinks through a series of swallow-holes into a cave system. This feature was to affect mining operations crucially, because of the problems the miners encountered in pumping water from their workings. Despite the use of steam pumping engines from the early eighteenth century, these water problems were finally solved only in the present century when two deep drainage levels were driven into the area, resulting in the lowering of the water level in the mines by some four hundred feet. Published work on the area has concentrated on its geology and the technical aspects of mining. During the First World War the urgent need for minerals led to the Flintshire and Denbighshire orefield, in common with other mining areas, being surveyed to assess its potential, and this work was published after the war by the Geological Survey. The volume on Flintshire and Denbighshire, by Bernard Smith, describes the geology and mine workings of the Mold area in some detail. It draws on much information gleaned from the local mining industry, which would 1 In the 1690s Edward Lhuyd noted that the river flowed underground for between three quarters of a mile and a mile to emerge at Hesp Alyn (SJ 192655) (R. H. Morris (ed.), Parochialia, i (1909), 92). 2 P. J. Appleton, 'Subterranean Courses of the River Alyn, including Ogof Hesp Alyn, North Wales', Trans. British Cave Research Association, i (1974), 29-42. B. Smith, 'Lead and Zinc Ores in the Carboniferous Rocks of North Wales', Special Reports on the Mineral Resources of Great Britain, xix (1921), 80-92. Mines in the Cathole area are also described in J. R. Earp, 'Mineral Veins of the Minera-Maeshafn District of North Wales', Bulletin of the Geological Survey of Great Britain, xiv (1958), 44-69.