Geoscientists have shed light on the enduring mystery of how the modern Euphrates River – central to the origins of human civilisation – came to exist.
Together with the Tigris, the Euphrates is one of the most historically significant river systems in West Asia, with its establishment around 1.6 million years ago thought to have played a key role in the development of the Fertile Crescent, or 'cradle of civilisation', in the Middle East.
Little has been known about the early history of the river, which stretches 3,000km from Turkey to the Persian Gulf.
Now, an international team including Professor Simon Lang from The University of Western Australia has concluded the Euphrates originated from two ancient river systems that once flowed across what is now Turkey and Syria into a partially dried out Mediterranean Sea.
In findings published in Nature Geoscience, the researchers report the two rivers merged to form the Euphrates as a result of millions of years of tectonic activity that redirected them away from the Mediterranean, towards the Arabian Plate.
Led by Dr Andrew Madof – a senior geologist with Chevron and Adjunct Senior Research Fellow with the UWA School of Earth and Oceans – the team examined seismic images of buried sediments, maps of ancient sediment deposits and river sediment-transport models to reconstruct the evolution of river systems in the area.
Their models suggest the two separate rivers – the Palaeo-Karasu and Palaeo-Murat – emptied vast quantities of water and sediment into a Mediterranean Sea basin that had partially dried out about 5.4 million years ago. At the time, the eastern Mediterranean was a vast salt desert.
The researchers describe how progressive tectonic activity including earthquakes in the Taurus Mountains caused the Palaeo-Murat to shift southwards around 3.6 million years ago, with the Palaeo-Karasu joining it around 2.8 million years ago.
"These diversions eventually created a single river network that evolved into today's Euphrates River about 1.6 million years ago and now flows into the Persian Gulf," Dr Madof said.
"The findings highlight the key role of tectonic processes – mountain building and earthquakes – in reorganising river systems over geological time scales."
Professor Lang, also from UWA's School of Earth and Oceans, said the study resolved longstanding uncertainty about the origin and development of one of the region's most important river systems, which had played a central role in shaping surrounding landscapes and environments.
"Understanding the evolution of this significant waterway is important for charting the later development of human societies that flourished in its floodplains," Professor Lang said.
The study was a collaboration between Chevron, UWA, the University of Oxford, the University of Texas at Austin and Utah State University.
Preview image:
5.4 million years ago the Palaeo-Karasu and Palaeo-Murat rivers — the precursor branches of the Euphrates — flowed into a partially dried out eastern Mediterranean, then characterised by a vast salt desert. At its southernmost extent, the Palaeo-Murat River approached the Palaeo-Nile, possibly marking the shortest distance between them in Earth's history. Reconstruction by Lina Jakaitė and Andrew S. Madof
Above: The modern Euphrates River
