The Euphrates… before it became the Euphrates. The river’s origins explained

How did the modern Euphrates River form, and what did its earlier, Miocene systems look like? Although this river is closely linked to the history of civilization, its geological origins have remained unclear. An international team of scientists has shed light on the history of the Euphrates’ formation in a study published in the journal *Nature Geoscience*.

Two rivers instead of one

Previous hypotheses have suggested various directions for the flow of the ancient Euphrates: toward the inland lakes of Anatolia, toward the Mediterranean Sea, or southeastward, toward the regions of Arabia. What was the reality?

The most important conclusion of the study is that the modern Euphrates was not always a single river. The authors propose the theory that it originated as two separate river systems: the Paleo-Karasu and the Paleo-Murat, corresponding to today’s main tributaries of the Euphrates—the Karasu and Murat rivers. In the late Miocene, both systems flowed generally from the northeast to the southwest, unlike the modern Euphrates, which flows toward the Persian Gulf.

Reconstructions indicate that the Paleo-Karasu was over 1,370 km long and had a sinuosity greater than 1.75, while the Paleo-Murat was even longer—exceeding 1,990 km—and had a sinuosity of no more than 1.65. These were vast, active river systems capable of transporting enormous amounts of water. The authors linked their traces to two previously known sedimentary deposits: Handere and Nahr Menashe.

The Mediterranean Sea as a partially dried-up trap

The key backdrop to the entire story was the Messinian salinity crisis, which occurred approximately 5.97–5.33 million years ago. During this period, the Mediterranean Sea was partially cut off from the ocean, leading to a sharp drop in its water level, the drying up of basins, and the accumulation of vast amounts of evaporites and sediments. The authors indicate that the drop in the erosion base could have been as much as 1.7–2.1 km.

It was during this period that the Paleo-Karasu and Paleo-Murat were thought to have supplied sediments to the partially dried-up eastern part of the Mediterranean Sea. The Paleo-Karasu fed the Handere deposit, while the Paleo-Murat fed the Nahr Menashe deposit. The Handere deposit was estimated at 8,313^km³, and the Nahr Menashe deposit at 3,372^km³. Both are believed to have formed over approximately 120,000 years, between 5.45 and 5.33 million years ago.

Rivers smaller than the Nile, but surprisingly productive

Sedimentation models yielded one of the most interesting results. Although the reconstructed Paleo-Karasu and Paleo-Murat river basins were roughly an order of magnitude smaller than the modern Tigris-Euphrates and Nile river basins, sediment transport within them was comparatively high. The median area of the Paleo-Karasu basin was approximately 2.5 ×^10⁵km², and that of the Paleo-Murat basin was approximately 9.9 ×^10⁴km². The sediment delivery rate for the Handere was calculated at 139.2 million metric tons per year, and for the Nahr Menashe at 56.2 million metric tons per year.

The authors also compare these values with those of the Rhône during the Messinian Salinity Crisis. The Paleo-Karasu is thought to have transported approximately 2.5 times more sediment than the Rhône, while the Paleo-Murat was comparable to it in this regard. Furthermore, the modeled water flows for the Paleo-Karasu exceeded those of the modern Nile, and in the case of the Paleo-Murat, only the lower end of the estimates was lower than that of today’s Tigris-Euphrates system. This is surprising, as this period is considered one of the driest in the region’s history. The authors suggest that local precipitation patterns, temperature, or episodes of intense rainfall may have been much more variable than general climate models indicate.

Tectonics as the Primary Driver of Change

The study showed that the history of the Euphrates was strongly influenced by tectonic movements. The authors point to the impact of the long-term uplift of Anatolia and fault activity, including that of the North Anatolian and East Anatolian faults. The reconstructed chronology reveals several stages of river capture and course changes. The Paleo-Murat is thought to have been directed toward the Persian Gulf in the early Pliocene, and the Paleo-Karasu joined it in the late Pliocene.

According to the presented model, the Paleo-Murat may have begun to form approximately 16.55 million years ago, while the Paleo-Karasu formed between 8.6 and 5.9 million years ago. About 3.6 million years ago, the reactivation of the East Anatolian Fault is thought to have redirected the Paleo-Murat to the southeast, forming the early Euphrates on the Arabian Plate. About 2.8 million years ago, the Paleo-Karasu merged with this system. Ultimately, the modern Euphrates is thought to have taken its present form around 1.6 million years ago.

When the Euphrates Almost Touched the Nile

One of the most vivid elements of the article is the reconstruction of the Late Messinian geography of the eastern Mediterranean. About 5.35 million years ago, the Paleo-Murat—the predecessor of the Euphrates—is thought to have ended its course in the region of today’s Levant, near areas associated with the Paleo-Nile. The authors estimate that the northern boundary of the Paleo-Nile and the southern boundary of the Paleo-Murat may have been less than 25 km apart. This may have been the shortest distance separating these two great river systems in Earth’s history.

The most important conclusion

The authors propose a new model explaining the origin of the Euphrates: the river was formed by the convergence of two ancient systems that initially drained into the partially dried-up Mediterranean Sea, were subsequently transformed by uplift and faults, and finally redirected their flow toward the Persian Gulf. In this interpretation, the Euphrates is therefore not a simple, ancient river with a constant course, but rather the result of a series of climatic, tectonic, and sedimentary changes.

The article’s final conclusion goes beyond the history of a single river. The reconstruction shows that geological processes occurring millions of years before the emergence of civilization created a river system that later became one of the foundations for settlement and the development of the world’s oldest known cities.

---

Source:

Madof, A.S., Laugier, F.J., Baumgardner, S.E. , et al. The Euphrates River in the Late Miocene drained into a partially desiccated eastern Mediterranean. Nat. Geosci. 19, 723–731 (2026). https://doi.org/10.1038/s41561-026-01962-x