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1 Geology of the Mediterranean
The geology of the Mediterranean is quite complex, involving multiple periods of drying and re-flooding from the Atlantic Ocean. Sediment samples from the bottom of the Mediterranean Sea that include evaporite minerals, soils, and fossil plants show that about 7.2 million years ago in the late Miocene period the Strait of Gibraltar was blocked and the Mediterranean Sea evaporated into a deep basin with a bottom over two miles below the world ocean level. The Sea was reduced to a couple of lakes with varying salinity and probably even dried up, leaving for quite some time a desolate salt basin.
The first solid evidence for this came in the summer of 1970, when geologists aboard the deep sea research and drilling ship Glomar Challenger brought up drill cores containing gypsum, anhydrite, rock salt, and various other evaporite minerals that only form from drying of brine or seawater. One drill core contained a wind-blown cross-bedded deposit of deep-sea foraminiferal ooze which had dried into dust and been blown about by a sandstorm and ended up in a brine lake. These layers were alternated with layers containing marine fossils, indicating the different drying and flooding periods. Other evidence of drying comes from the remains of many (now submerged) canyons that were cut into the sides of the Mediterranean basin by river action when it was dry. The area underwent repeated flooding and dessication over a 700,000 year span. About 5.4 million years ago at the start of the Pliocene period the barrier at the Strait of Gibraltar broke, premanently reflooding the basin.
In the last few centuries, humankind has done much to alter Mediterranean geology. Structures have been built all along the coastlines, exacerbating and rerouting erosional patterns. Many pollution-producing boats travel the sea that unbalance the natural chemical ratios of the region. Beaches have been mismanaged, and the overuse of the sea's natural and marine resources continues to be a problem. This misuse speeds along and/or confounds natural processes. The actual geography has also been altered by the building of dams and canals. The perfect little Sea that geology gave Western history is, in many ways, in great jeopardy.
The Mediterranean was once thought to be the remnant of the Tethys Sea, which formerly girdled the Eastern Hemisphere. It is now known to be a structurally younger basin.
Though the flooding of the Mediterranean happened long before any human being could observe it, it is sometimes referred as a possible basis for the Biblical story of Noah, or even the myth of Atlantis.
2 See also
3 External links
Mediterranean
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