Washing is one of the processes used in dressing metal ores. The mixed ore and rock which has been mined has by this stage already been broken up. This mixture is then shaken in water on a sieve, so that the heavier ore sank to form a bottom layer and the lighter top layer of rock could be removed. Washing was done in areas known as buddles. Early buddles were sloped areas covered in stone with stone sides. In the 19th century buddles were made of wood and from the mid 19th century circular stone buddles were also used. Although earlier the washing was done by hand, in the 19th century water power, horse power and steam power were all used to drive the sieves.