No 1 and No 2 pits started to be sunk in 1776 and by the 1790s the colliery was in production.[lower-alpha 1] The colliery used a number of pits over its life, Nos 1-9 were simply numbered, in addition there were the George, Stobbs Hill and West pits. Seven different seams were worked over the years ranging from around 100 feet (30 m) to nearly 850 feet (260 m).[9]