Geologists studying the Strait of Gibraltar have proposed a variation on an older hypothesis about how the Mediterranean Sea was filled in: a trickle of water from the Atlantic turned into a “gigantic flood” that filled in most of the sea in as little as a few months.
The sea had been emptied by evaporation when the Strait of Gibraltar closed up.
According to some scientists (whose timescale for the flooding is more than five million years ago), the sea had been emptied by evaporation when the Strait of Gibraltar closed up, blocking the inflow of water from the Atlantic Ocean and creating a land bridge between Europe and Africa. But while previous ideas suggested a sudden collapse of the land bridge (resulting in the hypothesized “Gibraltar Falls”), a Spanish team suggests a fast-flowing river carved out the land bridge instead, eventually flooding the sea in a matter of months.
The researchers believe a trickle of water began to erode the land bridge over thousands of years. But the rate of erosion and the water flow increased exponentially, until the inflow of water from the Atlantic Ocean was perhaps one thousand times that of the Amazon River. The team estimates that ninety percent of the sea was filled in as little as a few months’ time, raising the level of the Mediterranean Sea by more than 33 feet (10 m) per day while the Strait of Gibraltar deepened by more than a foot (0.4 m) per day.
“As soon as the first trickle of Atlantic water found the way through it, the feedback between erosion and water flow led to [that] enormous discharge in a short period,” said geophysicist Daniel Garcia-Castellanos of the Institute of Earth Sciences Jaume Almera in Barcelona.
University of Cambridge geologist Philip Gibbard calls the research “very convincing” and “perfectly reasonable.” We agree (though not with the timeline) in that the research illustrates the power of water. Just as a little water over a long time can have a substantial geological impact, so can much water over a short period of time. During the catastrophic events of the Flood year, a potent combination of tectonic, volcanic, and hydrodynamic forces could have reshaped the earth in a short time frame. Even old-earth researchers implicitly agree with the possibility when they posit alternative catastrophic models to explain earth’s geologic history.
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