Scientists may have just solved the Euphrates River’s mysterious origins
New research has revealed insight into the evolution of this influential waterway, which may have been created when two ancient rivers coalesced.
Nestled near the Euphrates River and its sister, the Tigris, in the fertile terrain of Mesopotamia, humans developed some of the earliest forms of civilization. The Euphrates powered profound innovations. Its flooding waters produced rich farmland, from which ancient cities emerged, paving the way for the development of writing, centralized power, and the law.
These breakthroughs happened less than 6,000 years ago, a historical blip. The Euphrates—which spans 1,740 miles between modern-day Türkiye and Iraq—was created more than a million years earlier. Certain details about its formation, however, have long remained a mystery to scientists.
New research published in Nature Geoscience on Monday may finally reveal its origin. Namely, that a separate pair of rivers flowing from Türkiye to the then-dry Mediterranean Basin converged and eventually formed the Euphrates between approximately 3.6 million and 1.6 million years ago—setting the stage for the eventual rise of the Fertile Crescent.
The research project began in 2014, when Andrew Madof, a geologist at Chevron, was examining data about marine sites off the coast of Lebanon while searching for natural gas. The data was assembled using seismic imaging, which created a picture of subterranean materials similar to an ultrasound. “Sound waves [bounce] off of individual layers underneath the seafloor,” Madof explains. “Depending on how long they take back, you can basically reconstruct [things] in three dimensions.”
Madof saw something unusual in the imaging. Scientists already knew about huge underwater salt deposits in the area—up to four kilometers thick in some parts— that had formed more than five million years ago during a period known as the Messinian Salinity Crisis, in which the Mediterranean Sea partially or fully dried out. Madof realized that sediment on top of the salt resembled river deposits. He wanted to understand what those waterways were, and where they had come from: “That basically started a 12-year-long journey for me,” he says.
After examining the seismic data, Madof and his co-authors reviewed on-shore geologic maps from the region, which showed that there were two rivers—a northern branch known as the Paleo-Karasu, and a southern branch called the Paleo-Murat—which spilled into the Mediterranean basin. Both waterways are named for their present-day counterparts, tributaries of the modern-day Euphrates.
The team also used computer modeling to estimate the size of the two rivers, which Madof says were enormous compared to the region’s modern-day waterways. Measured by flow and sediment output, the Paleo-Karasu was “larger than the Nile River,” while the Paleo-Murat was “larger than the modern Tigris and Euphrates combined,” he says. The rivers, he adds, only flowed onto the site of the dried-out Mediterranean for “about 120,000 years, which is geologically a very short interval of time.”
The team’s data suggests tectonic events—such as an earthquake or the formation of a mountain range—eventually pushed the water southeast and away from the Mediterranean, where they merged into one river before ultimately emptying into the Persian Gulf.
The paper provides crucial new insight into the Messinian Salinity Crisis, says Angelo Camerlenghi, a researcher at the National Institute of Oceanography and Applied Geophysics (OGS) in Italy. While “most scientists agree the Mediterranean Sea completely dried up during this period,” he notes, there has been a heated debate over how far sea level dropped and how freshwater eventually filled the Mediterranean Basin. (A small subset of researchers believe the Mediterranean didn’t fully dry out.) Madof’s research offers a new source of freshwater.
“I think this may be the end of a discussion that has lasted decades,” says Camerlenghi, who was part of a National Geographic Society-funded project studying a megaflood that likely ended the Messinian Salinity Crisis.
Because Madof’s research was based on computer modeling and remote seismic analysis, “rather than direct field evidence,” he admits there’s still some level of uncertainty about the path of these ancient rivers. Analyzing field samples would further corroborate his results, he says, and could ensure his estimates of the rivers’ paths are accurate. Camerlenghi says that these uncertainties “do not decrease the significance of the work.”
It would be difficult to overstate the degree to which the Euphrates may have influenced natural history—and human history, too. “When we look at modern landscape, or think about rivers, they're so ephemeral,” Madof says. Yet even small events in the context of planetary development, like an earthquake or mountain formation, can be impactful enough to potentially shape the development of great civilizations.
In the case of the Paleo-Karasu and Paleo-Murat, “if the rivers would not have changed direction and merged, there may have not been a Fertile Crescent,” he continues. The ongoing movement of the Euphrates also likely impacted human migration patterns for millennia, at Eridu and Ur, some of civilization’s first cities, which were abandoned after the Euphrates changed course.
It may be a series of intricately choreographed geologic processes that ultimately allowed modern society to exist. This discovery, then, helps us “understand the material and the environmental context that gave rise to the most important innovations in human civilization,” says Faisal Husain, a historian at Penn State University. “All aspects of what we call modern civilization were born in that place.”
