Around 6.2 million years ago, the Red Sea experienced a dramatic shift back to its marine identity, demonstrating Earth's ecosystems' resilience. A new study reports on a catastrophic influx of seawater from the Indian Ocean, refilling the desiccated Red Sea basin in less than 100,000 years. This event was notable in geological history for its suddenness and the profound changes it ushered in, transforming a once barren salt desert into a thriving ecosystem.
The transition occurred due to a massive flood that surged across the Hanish Sill, a natural barrier near the southern end of the Red Sea. This pivotal moment saw the recovery from complete desiccation, where layers of salt and gypsum had been deposited. Marine conditions returned suddenly, allowing the salt flats to be submerged again under seawater, fostering a back-to-life ecosystem.
"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 Dr. Tihana Pensa, a researcher at King Abdullah University of Science and Technology, as reported by Science Daily. The research explains how tectonic and climatic interactions could catalyze environmental changes.
Originally, the Red Sea was a narrow rift valley, filled with lakes and connected to the Mediterranean Sea to the north via a shallow strait. About 23 million years ago, the Mediterranean Sea poured into the Red Sea basin, transforming it into a wider gulf. However, this connection ceased, turning the Red Sea into an isolated saline basin marked by extreme desiccation and environmental stress.
The Red Sea experienced a salinity crisis over the years, where salt content continuously rose due to evaporation and minimal inflow. Geological records indicate that the desiccation lasted roughly 100,000 years. During this period, the sea level fell drastically, and the entire body of water disappeared, leaving a lifeless salt desert, similar to events in the Mediterranean Sea during similar times.
The violent flood ending the drought was so powerful that it cut a 320-kilometer-long and 8-kilometer-wide canyon into the seafloor, a geographical marker still visible today. This reconnection with the Indian Ocean not only refilled the basin but also allowed for the resurgence of marine life. Fossils of marine creatures such as sea snails and bivalves soon returned, underscoring nature's ability to recover. The transformation effectively reestablished a permanent connection between the Red Sea and global oceans. The study was published in the journal Communications Earth & Environment.
Written with the help of a news-analysis system.