The Salt of the Earth - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 78

The true story—and the huge scale—of the Mediterranean desicca-
tion puts all of these fictional and legendary accounts in the shade. 51
It was yet another of the succession of ocean wonders revealed by the
carefully manipulated drill-strings of the Glomar Challenger , as it sailed
in 1970 to discover what lay beneath the floor of the Mediterranean
Sea. On board were three scientists, Kenneth Hsü, Bill Ryan, and
Maria Bianca Cita—all of them on the track of the oldest stories of
this most history-packed of seas. What they found, as core after bore-
hole core was pulled out, was salt—prodigious thicknesses of salt.
The salt layers beneath the Mediterranean—once the borehole evi-
dence was integrated with seismic images of the strata—were shown
to be up to 3 kilometres thick. This was not some minor drying event.
This was wholesale destruction of an enormous inland sea, with
repercussions that were literally worldwide.
Meticulous analysis of the strata over the succeeding years has
revealed the sequence of events. A little under 6 million years ago,
connection of the Mediterranean with the Atlantic Ocean was broken
off, as tectonic changes led to a barrier forming at the Straits of Gibral-
tar. Given the dry climate, and the small river inflow, it may have taken
only a few millennia or so to reduce the beautiful blue Mediterranean
Sea to a blindingly white salt desert— quite unlike Conan the Barbarian's
sylvan Hyborian landscapes—with scattered lakes of concentrated
brine. The bakingly hot, devastated landscape lay up to 5 kilometres
below the level of the global ocean (which had been raised by about
10 metres as a result—because all that water had to go somewhere ). The
rivers flowing in, adjusting to the new geography, carved deep Grand
Canyon-like gorges into the freshly exposed landscape.
There is something to explain here, which is that even total desic-
cation of the Mediterranean Sea would only give rise to salt a few
tens of metres thick, and not up to three kilometres. What clearly
must have happened is that Atlantic waters periodically flooded in to