The Wieliczka salt deposit was formed approximately 13.5 million years ago, in the middle Miocene period . Its creation was closely linked to the formation of the Carpathian Mountains.

In the Tertiary, especially during the Miocene flysch, the Carpathians range was elevated and shifted a considerable distance towards the north. The Upper Jurassic limestone formations in the foreground yielded to the tectonic pressure, and a large trench called the Carpathian Depression was created in front of the elevated mountain range. The basin was filled by a long and narrow sea, whose southern shore was formed by the pre-Carpathians, elevated and folded in the lower Miocene, from which mountain rivers brought various minerals and rock fragments to the sea.

In the middle Miocene, the climatic conditions facilitated the evaporation of water and the sedimentation of rock salt. In some parts of the sea, rich organic life developed, and on the land, Mediterranean-type plants like magnolias, olives, redwoods, firs and pines grew. This is testified to by the carbonised remains of these plants, and traces of corals, snails and mussels, which are now found in the salt deposit.

Later tectonic movements caused the rocks to shift and previously formed salt deposits to be destroyed and broken into smaller fragments in the form of blocks of different sizes. This material, along with other rocks, was pushed onto previously formed layers of salt. It is also possible that the formation of deposits was influenced by sizeable undersea landslides. As a result of a number of processes, a rock formation, referred to as a blocky deposit, was formed. The lower part of the salt deposits found in the Mine preserved its continuity and layering, and is referred to as the layered deposit.

The upper part of the salt bed, the blocky deposit, is composed mostly of blocks of marl claystone, among which different-size salt cubes are located. It was in these blocks that the oldest and most beautiful chambers in the Wieliczka Salt Mine were carved.

The lower part, the layered deposit, is a complex of rock salt layers of different types. Due to the tectonic movements of the rock mass, these are formed into a series of folds.

The creation of the whole Wieliczka rock salt deposit was a short episode in the history of the Miocene sea and it lasted about 20,000 years.

The Wieliczka salt deposit contains exclusively rock salts. It extends from West to East along the nor the Carpathians, and it has so far been discovered to extend over approximately 10 kilometres. The deposit varies in width and ranges from 0.5 to 1.5 kilometres, and it also largely varies in thickness, which ranges from 1 to about 350 meters.
(info from webside http://www.kopalnia.pl/)

The Wieliczka Salt Mine, located in the town of Wieliczka in southern Poland, lies within the Kraków metropolitan area. The mine continuously produced table salt from the 13th century until 2007 as one of the world's oldest operating salt mines. It is believed to be the world's 14th-oldest company still in operation.

One of the most surreal tours ever... worth going to stand in the dark in a two-story ballroom carved by blind miners out of a giant block of salt 300 meters underground.

wenn man schon in krakau ist muss man auch das salzbergwerk anschauen. Sehr beeindruckend, vor allem die riesigen aus dem Salz gehauenen unterirdischen Kathedralen

900 steps down and you were in 135m under the ground. Awsome place!