Lithograph by Alfred Sumners after his own drawing, of a monumental open cast mining landscape. Slate has been mined here since the 16th century and is still used as a roofing material. At the start of the 21st century this slate quarry was still the largest in the world and being used. Published by T Catherall, Eastern Row, Chester and Bangor, on 12 July 1862.
© Science Museum / Science & Society Picture Library