Seas: Where Oceans Meet Land
What makes a sea, and how the Mediterranean once dried out and refilled.
Artist’s interpretation — SI render made for Before Saving Planets; science per cited sources (not a photo).
Ocean or sea?
Seas are smaller than oceans and are usually found where the land and ocean meet, often partly enclosed by land.
The Mediterranean dried up
About 6 million years ago, during the Messinian Salinity Crisis, the Mediterranean was cut off from the Atlantic and largely evaporated, leaving thick salt layers.
…and refilled
About 5.33 million years ago, Atlantic water broke through at the Strait of Gibraltar and refilled the basin, possibly within a few years — the Zanclean flood.
A sea being born
The Red Sea is a young sea forming as Africa and Arabia pull apart — part of the same rift system as the East African Rift.
Sources
Keep digging: Continents on the MoveOceans: Earth’s Blue EngineThe Dead Sea: Lowest Place on Land · Back to the Dig Quest