PLANET EARTH
Scientists have discovered a giant underwater canyon in the eastern Mediterranean Sea that likely formed just before the sea transformed into a mile-high salt field. The canyon formed around 6 million years ago at the onset of the Messinian salinity crisis (MSC), when the Gibraltar gateway between the Atlantic Ocean and Mediterranean Sea narrowed and eventually pinched shut due to shifts in tectonic plates. The Mediterranean Sea became isolated from the world’s oceans and dried up for roughly 700,000 years, leaving behind a vast expanse of salt up to two miles thick in some places.
As sea levels dropped, increasingly salty currents eroded the seabed and incised gullies several hundred metres deep along the steepest edges of the Mediterranean Sea. In a new study, researchers describe a giant U-shaped canyon located 75 miles south of Cyprus, in the depths of the Mediterranean’s Levant Basin. The 500-metre ‐deep and 6.2-mile-wide canyon, which the researchers named after the nearby Eratosthenes seamount, likely formed underwater shortly before salt piled onto the seabed. Unlike the more coastal gullies, the canyon had no older ‘pre-salt’ roots. “To explain the submarine formation of the Eratosthenes Canyon, we suggest incision by dense gravity currents scratching and carving the deep-water seafloor,” the researchers wrote in the study.
Weighed down with salt and sediment, these currents rushed along faster than the surrounding water and gradually scooped out enough of the seabed to form the colossal canyon. Precisely when this occu
