Messinic Salinity Crisis

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The Messinian Salinity Crisis (also Messinian Salinity Crisis, abbreviated to MSC) is a period of Earth history in which the Mediterranean Sea was partially or completely dried up. Here, up to three kilometres of powerful evaporative rocks (evaporite) deposited in the deepest sea basins. This happened about six million years ago until about five million years ago at the end of Messin, the last stage of the Miocene.

History of discovery
Already around 1833, the British geologist Charles Lyell had noticed a striking faunal section in various fossil sites in Italy, from which many creatures that had previously inhabited the Mediterranean Sea disappeared and were displaced by other organisms. The latter should then largely give rise to today's fauna. With this striking event, Lyell defined the boundary between the geological epochs of the Miocene and the Pliocene.

First indications
In the plain of Valence in southern France, towards the end of the 19th century, In the 19th century, during the construction of drinking water wells, a gorge was discovered hidden under quaternary gravel, which was inexplicably cut deep into the crystalline underground. Later, it was possible to detect this gorge throughout the Rhone valley between Lyon and the Camargue, where it was filled with marine sediments of the Pliocene. Some French and Italian paleontologists even then considered a temporary dehydration of the Mediterranean Sea to explain this phenomenon. At the beginning of the 20th century. In the 20th century, such ideas were widespread, but were considered highly speculative. For example, science fiction author H. G. Wells, who had studied geology in his youth with Vincent Illing in London, used the idea in his short story The Grisly Folk.

In 1958, seismic measurements by North American oceanographer Brackett Hersey revealed a previously unknown geological structure that was always about 100 to 200 meters below the bottom of the Mediterranean Sea. Since this area, the so-called “M-reflector”, closely followed the current profile of the seabed, it was obvious that it was a hard rock layer that had deposited uniformly and coherently throughout the Mediterranean at a certain time. In addition, the seismic profiles featured structures reminiscent of salt stocks rising from the depths and permeating the overlapping sediments. Many geologists then suspected that the salt must have come from the time of the Permian or Triassic period, because during these geological ages, more than 200 million years ago, rich salt deposits were formed in many parts of the world, including those of the Zechstein series of Central Europe. However, since the previously known Permian and Triassic salt deposits are located in a relatively flat epicontinental sea, i.e., over a continental crust