If we travel to the past and stand in the Strait of Gibraltar 5.96 million years ago, we would see how it was closed and not open as is the case right now. This is something that left a Mediterranean isolated from the Atlantic, causing its water to begin to evaporate and leaving only a kilometer of salt on the bottom in an event known as the ‘Messinian salinity crisis‘. But now, the method by which it was ‘opened’ to give rise to the Mediterranean that we know today has undergone different nuances.
What we knew. Until now it was thought that hundreds of thousands of years after this closure of the strait, a tectonic collapse occurred that reopened the passage, causing what is known as ‘Zanclian Megaflood‘. This was nothing more than a large waterfall in Gibraltar which supposedly filled the entire sea in a matter of months or a few years.
In anyone’s mind this may be something great and like a real Hollywood movie, but the reality is that science is beginning to show many doubts that this exists.
The origin of the myth. This mental image of the Strait of Gibraltar did not come out of nowhere, but in 2009 the magazine Nature public a study that modeled how the Atlantic would have breached the Gibraltar barrier, carving a deep canyon and pouring water at great speed. Without a doubt this was the perfect scenario to explain the erosive scars on the seabed.
Although he was not alone, since later studies were added to this that, although they clarified how the salinity was stabilized after the event, they continued to find clear evidence in the geology that pointed to yes there were flooding episodes very abrupt and a violent flow of water that would make sense with this large waterfall. The problem is that this great phenomenon was oversimplified when complexity is its great characteristic.
There are changes. Fifty years after the first hypotheses were raised, a large study published in 2025 pointed out that the connection between the Atlantic and the Mediterranean could have continued to exist for much of this period of time. But this is something that makes us raise another question: how is it possible then that kilometers of salt accumulated on the bottom if the sea did not dry completely?
This is where the ‘‘paradox of the Mediterranean’ which suggests that changes in precipitation and the immense contribution of fresh water and sediment from European and African rivers allowed certain water levels to be maintained. That is why that scene of a completely dry Mediterranean is not so true, since only a little water was lost and it effectively made the water very salty.
And more tests. Besides, studies on the Arch of Gibraltar demonstrate that the reduction in connectivity was due to a constant tectonic tug-of-war. That is why the pass never became a hermetic wall of solid rock that would break overnight, but rather a system of thresholds that allowed continuous leaks.
The reality. After all, the question we must ask ourselves is whether there really was a flood or not, and here science suggests that the truth is somewhere in the middle. The latest evidence tells us that the total disconnection was real, but very brief in geological terms, since when the Atlantic finally regained definitive control over the Mediterranean basin, the filling was undoubtedly rapid and spectacularly rapid, although not necessarily through a single and apocalyptic cataract in Gibraltar. A scene that in the end can be much more boring for many.
Images | wirestock
GIPHY App Key not set. Please check settings