Red Sea dried out and reflooded in catastrophic event 6.2 million years ago
Scientists at King Abdullah University of Science and Technology have confirmed that the Red Sea completely dried up about 6.2 million years ago, turning into a barren salt desert. A sudden flood from the Indian Ocean then refilled the basin in less than 100,000 years, carving deep channels and restoring marine life. This event, detailed through seismic imaging and other evidence, highlights the Red Sea's dramatic geological history.
The Red Sea's formation began with the separation of the Arabian Plate from the African Plate around 30 million years ago, initially creating a narrow rift valley filled with lakes. About 23 million years ago, it connected to the Mediterranean Sea through a shallow sill, allowing marine life to thrive, as evidenced by fossil reefs near Duba and Umluj. However, between 15 and 6 million years ago, increased evaporation and poor circulation led to high salinity, causing the extinction of marine life and filling the basin with layers of salt and gypsum. This culminated in the complete desiccation of the Red Sea around 6.2 million years ago, severing its northern connection and leaving a salt-filled basin.
A volcanic ridge near the Hanish Islands blocked the southern connection to the Indian Ocean via the Bab el-Mandab strait. Then, approximately 6.2 million years ago, seawater surged across this barrier in a catastrophic flood. The torrent carved a 320-kilometer-long submarine canyon, still visible on the seafloor today, and rapidly refilled the basin, drowning salt flats and restoring marine conditions in under 100,000 years. This reflooding occurred nearly a million years before the Zanclean flood that refilled the Mediterranean Sea.
"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 Dr. Tihana Pensa of KAUST. "The flood transformed the basin, restored marine conditions, and established the Red Sea's lasting connection to the Indian Ocean."
The study, published in Communications Earth, used seismic imaging, microfossil evidence, and geochemical dating to pinpoint the timeline. "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 Professor Abdulkader Al Afifi.
The Red Sea now serves as a natural laboratory for studying ocean formation, salt accumulation, and the interplay of climate and tectonics over millions of years, underscoring its links to global ocean changes and past environmental extremes.