Submarine Channels

The natural world is a display case of wonders!:

To find out more about what's going on under the waves, Dan Parsons, a research fellow at Leeds' School of Earth and Environment, and his international colleagues sent a (bright yellow) robot sub down to the bottom of the Black Sea to carry out the first in-depth examination of a submarine channel.

...The scientists found that the channel is filled with fast-moving salty water spilling from the Mediterranean into the less salty Black Sea at the two bodies' meeting point: the Bosphorus Strait. "The Mediterranean-derived water flows as a result of gravity, acting on the density difference that's produced by higher concentrations of salt," Parsons told AOL News. "It's essentially the same process that takes place when you pour bubble bath into water and it sinks and flows along the bottom of the tub toward the plug hole."

Except the Black Sea is a very big bathtub: Some 22,000 cubic meters of water pass through the submarine channel every second. That's 350 times more than the flow of England's Thames, or roughly that of the Missouri River where it flows into the Mississippi. This torrent moves along at around four miles per hour for some 37 miles, then it hits the edge of the sea shelf and dissipates into the depths.

Parsons says that this channel -- which, if located on land, would be the world's sixth largest river based on the amount of water flowing through it -- would likely have started to form at the end of the last ice age some 8,000 years ago. As melting glaciers pushed global sea levels close to their current high point, the Mediterranean would have breached through the Bosphorus -- then a thin strip of dry land -- and splashed into the Black Sea. (Which at the time was just an isolated freshwater lake.)