Prehistoric Atlantic Ocean was twice as salty

Adam Khor

http://blogs.discovermagazine.com/d-brief/2013/11/13/prehistoric-atlantic-ocean-was-twice-as-salty-as-today/#.UofixSckIYI

Capt'n Midnight

the Mediterranean was very salty 6 million years ago, before it fully dried out

Adam Khor

It dried up?? :eek:

Capt'n Midnight

if you remember that it gets cooler with altitude then it also gets hotter when you go below sea level, very hot desert




https://en.wikipedia.org/wiki/Messinian_salinity_crisis#Several_cycles


http://phys.org/news179598629.html

Capt'n Midnight

http://www.clas.ufl.edu/users/pciesiel/gly3150/med_story.html

During the late Miocene (~6 million years ago) compressional tectonic forces and lower sea level combined to bring the Gibraltar sill above sea level. As the last Atlantic waters dripped over into the Mediterranean, this body of water began to become a hypersaline lake as evaporation exceeded precipitation. Over the next 1000 years, this lake became lower and progressively saltier. Finally deep basins thousands of feet deep became little more than salt flats surrounded by the exposed marginal walls of the European and African continental slopes. Surrounding rivers flowed outover the exposed continental shelves and then cascaded in enormous braided waterfalls into the deep basin. The Mediterranean had become a deep hole, dwarfing the Grand Canyon. The surrounding climate of the region became cooler and drier as an important moisture source disappeared.

A single drying up of the Mediterranean would only form salts or evaporites 100 meters thick, however, thicknesses of 1000 to 2000 meters floor parts of the basins. This tells usthat over 2 million years, the Mediterranean was not continually dry. Periodically, waters would cascade of the sill, partially filling the basin only to evaporite again. Such occurrences may have occurred as many as 40 times.