The Mediterranean Sea dried up 5.5 million years ago and offers today's humanity a sobering lesson

Since the 1970s, several generations of marine geologists and geophysicists have confirmed the existence of a one to three kilometer thick layer of salt buried in most of the deeper parts of the Mediterranean Sea. That's nearly a million cubic kilometers of salt, indicating a brief period when the Mediterranean Sea was isolated from the rest of the world's oceans—brief in geological terms, as the episode lasted about 190,000 years. The Mediterranean basin, trapped between two continents that are now moving closer by up to two centimeters each year, was cut off from the Atlantic. Due to the dry climate in the region, its waters quickly evaporated, leaving behind a huge amount of salt. This episode, known as the Messinian Salinity Crisis (Messian is the last period of the Miocene), is the largest extinction event to hit the Earth since the meteorite that wiped out the flightless dinosaurs 65 million years ago and ended the Mesozoic Era. (Daniel García-Castellanos and Konstantin Agiadi, more at phys.org)