December 23, 2024 at 9:47 am

How The Mediterranean Sea Once Ceased To Exist, Leaving A Salty Basin In Its Wake

by Kyra Piperides

Source: Pexels/Luciann Photography

Beloved amongst fisherman, holiday makers, and retired expats, the Mediterranean Sea is a firm favorite ocean for many.

With the historic city of Athens, the beautiful white walls and blue domes of Santorini, the iconic seaside metropolis of Barcelona, and the home of Game of Thrones, Dubrovnik, all sitting alongside this temperate sea, you can understand why it is so beloved.

But did you know that it hasn’t always comprised the salty blue depths that it does now?

In fact, the Mediterranean Sea was, at one time, not even a sea at all. In fact, this now firmly aquatic areas once became a large, salty desert.

This is all because of the Messinian Salinity Crisis. Between 5.5 and 6 million years ago, the Atlantic Ocean became unable to flow into the area that is now known as the Mediterranean Sea.

Source: Pexels/veeterzy

Why? Well it is all down to the earth’s tectonic plages.

As you may already know, our planet’s continents did not always look the same way they do now. In fact, billions of years of tectonic shift have caused our continents to form in the way that we are familiar with, but this only happened through a whole lot of seismic action.

As tectonic plates rub on or crash into one another, land masses move and mountain ranges are formed. At the same time, as the plates move away from one another on their other sides, earthquakes happen and magma from the earth’s core rises up to form fresh crust.

This ultimately ends in changes in the shapes and flow of oceans too, with mountain ranges and newly formed areas of land becoming obstacles to the movement of water.

So, millions of years ago, the movement of the African and Eurasian tectonic plates caused a ridge to form, blocking the Atlantic Ocean from flowing into the Mediterranean Sea. At the same time, scientists believe that a huge ice sheet was forming in the Antarctic, lowering the planet’s water levels and worsening the situation between the Atlantic and the Mediterranean.

Source: Pexels/Michael Giugliano

Since the Mediterranean is located in a warmer part of the world, it evaporates faster than the water in many other oceans. This causes its water to be more salty, since salt compounds are left behind to dissolve into a reducing volume of water.

As the Mediterranean Sea evaporated over time, salt was left behind. Since the Atlantic Ocean was no longer able to refill it, a deep layer of salt was left behind once all the water had evaporated, with scientists predicting this layer to have been 3,500 meters thick.

So how did this salty basin become the Mediterranean Sea once again?

Well the situation reversed in exactly the same way that it was caused.

The African and Eurasian tectonic plates continued to move. After an extremely long drought (lasting somewhere up to two million years) the rocky formations at the Strait of Gibralter that had prevented the Atlantic Ocean from accessing the Mediterranean sea broke down.

The resulting flood, the Zanclean megaflood, was unimaginably powerful, causing the Atlantic waters to rush back into the basin where the Mediterranean Sea had once been. This extreme flooding event re-created the Mediterranean Sea that we all know and love.

Still extremely salty, thanks to the high levels of evaporation, human settlers made the most of this sea by building the settlements that we now vacation in. These spots were ideal for fishing (a food source) and transportation and trade by boat. They were also very beautiful, though this was probably less of a consideration.

Source: Pexels/Nilina

So will it happen again? Well probably not in our lifetime. But the factors contributing to the Mediterranean’s quick evaporation rates haven’t changed – if anything, they’ve got worst. There is always a chance that with continued continental drift and tectonic activity, the Mediterranean Sea could fully evaporate once again.

If you thought that was interesting, you might like to read about why we should be worried about the leak in the bottom of the ocean.