This the second of two articles on the Wieliczka Salt Mine in Poland. The first appeared in Issue  and covered some of the highlights that can be seen there. This one covers some more of these features, but also deals with the geology of the site.
The journey began in the Miocene period, which was about 13.5mya, when the crystallisation of salt dissolved in sea water occurred. These salt deposits combined with rocks that normally accompany salt that occupied what was known as the Pre-Carpathian Sink. Subjected intensively to the tectonic process, these salt deposits shifted and folded. About 6,000 years ago, the local people of Wieliczka in Poland started to produce salt by evaporating salty water.
In the thirteenth century, when the sources of the salty water were almost exhausted, they began to sink wells hoping to find salty water under the ground. In 1289, at the bottom of one of the wells, the first lump of the grey rock salt was found and that was the beginning of the Wieliczka Salt Mine. Today, the mine is divided into two portions. While its upper stratum is the block type, its lower stratum is of the stratified type; and visitors learn about salt, its excavation and types as they walk with their designated guides across chambers, pathways, tunnels, chapels and lakes.
In the olden days, the equipment to transport salt from one level to another included wooden carts and trolleys. At Wieliczka, these are well conserved because salt has preserved the wood by coating it. However, salt corrodes metal and, to slow the corrosion down, the wheels of the trolleys have been coated with tar. In fact, the salt mine has a unique collection of original miner’s equipment.