EARTH × CLIMATE

The Messinian Salinity Crisis

~5.96 to 5.33 million years ago

Phanerozoic · Cenozoic · Neogene · Miocene

The Mediterranean lost its link to the Atlantic and largely dried out between 5.96 and 5.33 million years ago, leaving salt flats a kilometre below sea level and up to two kilometres of evaporites, the minerals left when seawater dries.

The Messinian salinity crisis is the interval in which the Mediterranean lost its link to the Atlantic and largely evaporated. It is named after the Messinian, the geological age during which it occurred. The evaporation left salt flats a kilometre below sea level. It also left up to two kilometres of evaporites on the floor of the Mediterranean basin. The Atlantic then broke through again at Gibraltar. A channel is cut across the strait, two hundred kilometres long and more than two hundred and fifty metres deep. From that channel, researchers estimate the scale of the refilling: a discharge, the volume of water flowing in a given time, of perhaps a thousand times that of the Amazon.

Why it matters

An entire sea disappeared and was refilled within less than a million years. The channel cut by the flood of Atlantic water persists beneath the Strait of Gibraltar. Researchers estimate from that channel and from models whether the refilling took months or centuries. Either duration is very short for the filling of a sea.

Dating & uncertainty

The salt on the floor of the Mediterranean basin, up to two kilometres thick, is not disputed. Researchers still debate two points: the depth to which the level of the sea fell, and whether the refilling was a flood of months or a rise of centuries. They argue from erosional channels, which are channels carved by flowing water, and from models.

Earth history as one day

23:58:061 min 53 s before midnight

if Earth’s 4.54 billion years were compressed into a single day