History of salt beds

All salt deposits are of sea-origin and were formed around  250 mln years ago. Rock salt occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas and seas. Salt beds may be up to 350 m thick and underlie broad areas.

In Poland salt deposits were formed around 225-210 mln years ago and are located at the depth of 3-6 km underground. The oldest signs of salt extraction were discovered in Inowrocław, they come from the 7th-8th century B.C.