Winsford rock-salt mine is Britain's oldest working mine and lies 200 metres under the Cheshire coutryside. It is the UK’s largest salt mine, providing rock salt for de-icing roads during cold winter weather.Salt beds were formed back in the Triassic period, when the UK was still attached to Europe. The combination of inland seas and desert envrionments led to a slow evaporation over many millions of years, resulting in the formation of salt beds which lie under Cheshire and the surrounding areas. Although the salt bed is fragmented it can be found from Carrick Fergus, Northern Ireland, under the Irish Sea, reappearing in central England. It then dips under the North Sea, with the final part of the salt bed lying across Europe.Towns around Winsford like: Northwich, Middlewich and Nantwich, all take their names from salt production with ‘Wych’ often meaning ‘brine town’. Salt was first found in Northwich in 1670 and in Winsford in 1844. Two shafts were installed at Winsford, with miners being lowered into the shafts by bucket. In 1928 the last mine in Northwich was flooded which resulted in the rapid expansion of Winsford Mine which now consists of three shafts.