c. 3 Million BCE

The Dead Sea

The breakup of continental landmasses creates enormous valleys or rifts in the crust. The effects of the East African rift extend much farther than just the African plate. A complex zone of interactions among the African, Arabian, Indian, and Eurasian plates extends to the north of the East African rift zone, along the Red Sea and into the Middle East and beyond.

In particular, continuing compression between the African and Eurasian plates to the west and extension of the African plate in the major rift zone to the south have produced a region of roughly north–south valleys within parts of the Arabian Peninsula, especially regions encompassing modern-day Israel, Jordan, and Saudi Arabia. The Dead Sea, the lowest elevation lake (not really a “sea”) anywhere on Earth, lies within one of these extensional valleys, the full extent of which runs from the Sea of Aqaba to the south and up to the Sea of Galilee to the north.

The surface waters of the Dead Sea are currently at about 1,400 feet (430 meters) below sea level, and the deepest parts of the sea are about 1,000 feet (300 meters) below that. The volume of water in the Dead Sea is about the same as that in Lake Tahoe in the western United States, but the Dead Sea is hypersaline—extremely salty—compared to most other inland lakes or seas on Earth. With a salinity of about 34 percent (nearly 10 times saltier than ocean water), very few plants and animals can thrive in and around the Dead Sea.

How did the Dead Sea get so salty? A leading hypothesis is that the Arabian Peninsula has been undergoing multiple cycles of uplift and subsidence over the past tens of millions of years and has occasionally been inundated with seawater. The region apparently underwent a last major episode of uplift around 3 million years ago, cutting off the basin from the rest of the Mediterranean and creating a true large inland sea that was the precursor to the Dead Sea. As those waters evaporated, enormous salt deposits were formed and the salt concentration of the remaining waters increased dramatically—earning the shrinking lake its unfortunate but relatively accurate “dead” moniker.

SEE ALSO Pangea (c. 300 Million BCE), The Atlantic Ocean (c. 140 Million BCE), East African Rift Zone (c. 30 Million BCE), The Mediterranean Sea (c. 6–5 Million BCE), The Caspian and Black Seas (c. 5.5 Million BCE), Death Valley (c. 2 Million BCE)

Salt-encrusted rocks line the shore of the slowly evaporating Dead Sea.