Formation of potash and magnesium deposits –
Potash deposits were formed more than 230 million years ago through the evaporation of seawater during the Zechstein period.
According to Ochsenius’ “bar theory”, the salty sea water flooded across shallow barres into lagoons, where it evaporated. Specific conditions during the solar evaporation phase resulted in the formation of deposits not only rich in potash minerals but also containing magnesium sulphate. This process repeated itself over the centuries so that two or more potash deposits were formed on top of each other.
Over millions of years, the original deposits were covered by non-saline sediments, mainly variegated sandstone, shell limestone and Keuper.