This was discovered by a singular man named Ivan Sergeevich Chumakov , a Soviet engineer who participated in the construction of one of the largest dams in the world: the Aswan High Dam in Egypt . Chumakov was tasked with drilling a series of holes in the bedrock from one side of the Nile to the other. The objective was very clear: to locate a safe base on which to lay the foundations for the dam.
When he started digging in the middle of the river in the second half of the 1950s he cut through the usual ten to thirty feet of silt and sand. Chumakov continued another 270 meters until finally he found a granite substratum: he had just discovered an incredibly deep and narrow canyon belonging to what seemed to be an ancient buried river . In the analysis of the mud, the Soviet technicians found tiny shells of marine plankton and shark teeth with an age of five million years. Marine plankton and sharks upstream, hundreds of kilometers from the coast? That couldn’t be. The only possible explanation was to suppose that this mysterious ancient river was not such, but a very narrow arm of the Mediterranean . Of course that was much more incredible.
To find an explanation for the fact that salt water had invaded the course of a river up to 700 kilometers inland, Chumakov ventured an explanation that, even within the canons of the best scientific heterodoxy, it would be convenient to label as risky: he concluded that the surface of the Mediterranean had sunk more than 1,500 meters below its current level.
Thus, while the Mediterranean was drying up, the Nile was cutting a deep valley to adjust its slope as the coast sank. And when the Mediterranean finally filled with water again, the gorge was flooded and the river became an estuary. The advance of sea water was so rapid that the Nile could not prevent the Mediterranean from reaching Aswan.
However, Chumakov’s discovery went completely unnoticed for years , and was not recovered until the oceanographic ship of the University of California and the US National Science Foundation, the Glomar Challenger, decided to study the sediments of the bottom of the Mediterranean.
The sedimentary layer of the seabed is an important library of information. The sediments are composed of mud, calcareous mud, sand and rocks, following a scrupulous script written, fundamentally, by the climate. The erosion of the mountains, the transport of desert dust by the wind, the movement of the waters, the freezing and melting of the polar ice caps and the existence of a multitude of living beings that colonized the land long ago, whether it was or not covered by the waters, and that left their fossilized skeletons as an imperishable remnant of their presence.
In this way, the history of the Earth is inexorably deposited with sedimentary particles over millions of years, slowly building the surface of the seabed, with thicknesses that reach several hundred meters.
Now, sometimes storms happen in the ocean basins that stir up the accumulated sediments and get them suspended in the water again. In this way, entire pages in the history of an ocean can be erased. For this reason, oceanographers must carefully look for those areas where the sedimentary record is best preserved. Only in this way can they obtain reliable records in their drilling on the sea floor.
This was the objective of the Glomar Challenger in a scientific expedition that began in August 1968 and lasted for 15 years, the Deep Sea Drilling Program. He crossed the Mid-Atlantic Ridge between South America and Africa and took soil samples at specific locations . Thanks to paleontological and isotopic dating studies, it was possible to determine the age of the sediments collected in the drilling cores, and thereby prove a theory that had been formulated a year earlier, in 1967, by Dan McKenzie and RL Parker in the journal Nature . In a valiant effort at synthesis, these geologists showed that geophysical accidents were explained if it was assumed that the earth’s crust was similar to a soccer ball, composed of rigid plates floating in the magma sea of the mantle and colliding with each other: it had just been born plate tectonics, the central theory of modern geology. The samples obtained by the Glomar Challenger demonstrated without any doubt the expansion of the seafloor and, consequently, the veracity of plate tectonics.
But his discoveries did not stop there. During 1970 the ship’s geologists directed their efforts to the Mediterranean, in particular 70 kilometers from Barcelona, along with the Balearic Islands under the supervision of Kenneth Hsu. The drill cores they extracted contained gypsum, anhydrite, rock salt and evaporites, sedimentary rocks that form by crystallization of dissolved salts in coastal lakes and seas. This was the first solid evidence that the Mediterranean Sea was once a desert, with drying lakes and muddy coastal plains evaporating under a scorching sun.
