Welsh Journals

THE RECLAMATION OF SLATE WASTE JOHN C. SHELDON INTRODUCTION Welsh slate originated from consolidated clays and shales which were subjected to long continuous pressures during mountain building movements. The loss of water from the sediments and the re-crystallisation of the minerals during compaction produced a rock with perfect cleavage planes. Slate is chemically inert, very hard, durable and waterproof. These characteristics, together with the ease of splitting the rock, were the reasons for the important development of the slate tile industry during the nineteenth century. The great movements of populations during the Industrial Revolution meant an increase in house building and the consequent demand for roofing materials. To cope with the insatiable demand for slate tiles, thousands of men were recruited to the small mountain villages of North Wales to quarry slate; at the peak of the industry's rise, over 4,000 men were employed in the quarries at Blaenau Ffestiniog. However, because of rising costs and the import and development of cheaper alternatives to the slate tile, the industry of tile making has slumped (Fig. 1). Yet, the quarries within the county of Gwynedd still produce about 75% of all the slate quarried in this country. New outlets for the rock are being found, abandoned quarries are being re- opened and once more slate quarrying is becoming an important industry in North Wales. The environmental effect of slate quarrying is devastating, no matter whether it is extracted from underground beds as at Blaenau Ffestiniog or Fig. 1 Production of slate between 1913-1970 (from the "Report of the Commission on Mining and the Environment", 1972).