Geology is more than just studying rocks. With advancing technology, scientists are reconstructing Earth's makeup in greater detail, uncovering how landscapes and oceans looked millions of years ago.
A fascinating geological event is the desiccation of seas, where bodies of water are cut off from the open ocean and slowly evaporate, leaving behind vast salt deserts. Famously, the Mediterranean Sea dried up about 6 million years ago and only refilled during the dramatic Zanclean flood, after remaining mostly dry for nearly 700,000 years.
Now, researchers at King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia, have found evidence that the same phenomenon occurred in the Red Sea around 6.2 million years ago. Initially connected to the Mediterranean near today's Suez Canal, the Red Sea rejoined the world's oceans through a catastrophic southern flood that carved out the Bab el-Mandab Strait we know today.
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Massive Flood Revived the Red Sea
Once tectonic shifts cut off the Red Sea's connection to the Mediterranean, the basin became a vast enclosed water body bordered by what is now Egypt and Saudi Arabia. In their study, published in Nature Communications Earth & Environment, the KAUST team used seismic imaging, microfossil analysis, and geochemical dating techniques to show that the Red Sea completely dried out for roughly 100,000 years.
Blocked from the Indian Ocean by a volcanic ridge to the south, the basin remained desiccated until an enormous flood about 6.2 million years ago refilled it with seawater -- and life.
"Our findings show that the Red Sea basin records one of the most extreme environmental events on Earth, when it dried out completely and was then suddenly reflooded about 6.2 million years ago," said lead author Tihana Pensa of KAUST in a press statement. "The flood transformed the basin, restored marine conditions, and established the Red Sea's lasting connection to the Indian Ocean."
Marine Life Flourishes In the Red Sea Today
The Red Sea was born around 30 million years ago when the African Plate began separating from the Arabian Plate. What started as a chain of lakes along a narrow valley eventually connected to the Mediterranean about 7 million years later. Fossils from that period reveal flourishing marine life, until rising salinity and evaporation once again left the basin dry after the Mediterranean connection was severed.
Today, coral reefs line the Red Sea's coastlines, supported by its link to the Indian Ocean, which continuously replenishes it with seawater. Traces of the flood that revived the Red Sea remain visible: a 200-mile-long underwater canyon carved by torrents of water rushing into the basin 6.2 million years ago.
Earth's Oceans Are Resilient
The Red Sea's desiccation actually ended almost a million years before the Mediterranean's Messinian Salinity Crisis came to a close, highlighting how these extreme events unfolded on different timelines.
"This paper adds to our knowledge about the processes that form and expand oceans on Earth. It also maintains KAUST's leading position in Red Sea research," said co-author and KAUST professor Abdulkader Al Afifi.
According to the press statement, the Red Sea serves as a living laboratory for studying how oceans form, how massive salt deposits accumulate, and how climate and tectonics shape marine environments over millions of years. Its history underscores the resilience of Earth's oceans: even after experiencing extreme desiccation, the basin returned as a thriving ecosystem, offering scientists key insights into global ocean change.
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