I definitely prefer the catastrophic interpretation of events. How boring if it had taken 10,000 years to re-fill the Mediterranean Sea!!
About 5.9 million years ago (mya) a tectonic shift occurred. The African Plate and the European Plate moved towards each other and closed the Strait of Gibraltar, cutting off the Mediterranean Sea from the Atlantic Ocean. The Mediterranean Basin, over the next 1,000 years, dried up (called the “Messinian Salinity Crisis”), leaving a thick layer of salt at the bottom. With a depth ranging from 3 to 5 km (2 to 3 mi), the waterless Mediterranean must have dwarfed today’s Grand Canyon. It was a hot desert landscape that reached temperatures of up to 80 C (175 F) at the bottom. The few remaining hypersaline pockets of water were unable to support any life. Rivers that drained into the basin, such as the Nile, cut deep canyons as they cascaded into the abyss. It must have been a dramatic sight!
Elsewhere on earth, the drying of the Mediterranean meant a rise in global sea levels by 10 m (33 ft), also making the world’s oceans less saline and more prone to freezing. During the next 630,000 years, moving subduction zones caused the periodic opening and closing of the Gibraltar Strait, but the longest and last time the Strait was closed was between 5.59 and 5.33 mya (260,000 years).
The eventual opening of the access to the Atlantic Ocean must have been quite an event. The Mediterranean was almost completely empty when the barrier broke and water rushed in. The event, called the “Zanclean Flood” is a widely accepted scientific theory, but the length of time it took to re-fill the Mediterranean Basin is still being debated.
As I stand at Europa Point in Gibraltar and look across the 14 km (9 mi) wide Strait towards Africa, I try to imagine the scene from my vantage point. At a flow rate 1,000 times greater than the flow of today’s Amazon River (which is 80 km [50 miles] wide at its mouth during the dry season), the roar is deafening, the spray is obstructing my view and the ground is moving under my feet. At this rate it will take 2 years for the Mediterranean Basin to reach global sea levels.
Not all scientists agree with this interpretation of events. Some believe the opening in the flooding channel was shallow, the water flow slow and the filling a gradual process. In that case the filling of the Basin would have taken 10,000 years.
I close with some real estate investment advice: don’t buy waterfront at the Mediterranean. If the Strait of Gibraltar closes again, you’ll be looking into a gaping hole just 1,000 years later.