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Dutch researchers have identified the largest lake ever

Dutch researchers have identified the largest lake ever

The lake, which no longer exists, must have contained ten times more water than all modern lakes combined.

The lake was located in the heart of Eurasia. It has been known for some time that an enormous body of water could be found here about 12 million years ago. Researchers have even given it an earlier name: Paratethys. However, it was not clear whether the sea was inland (such as the Black Sea) or an inland lake (such as the Caspian Sea). Because although many marine organisms lived in the water, they all evolved slightly differently from the species that lived in the seas at the same time. New study – published in the journal Scientific Reports – Now reveals that Paratethys was indeed a lake – and with that it goes straight to the books as the largest lake ever. In addition, in the study, researchers – including scientists from Utrecht University – determined more precisely the size of this lake and how it has deteriorated over time.

huge lake
For example, the researchers wrote that the lake covered about 2.8 million square kilometers at its peak. “This is bigger than the modern Mediterranean,” researcher Dan Palko said. The lake was home to an estimated 1.77 million cubic kilometers of brackish water at the time. “More than ten times the fresh and salt water currently stored in lakes.”

Stretching all the way from the eastern border of modern Austria beyond the borders of Uzbekistan, the lake was formed about 12 million years ago. A huge sea separated from the ocean and became a lake. Sea animals, as they are, became trapped in the lake and went their own way, evolutionarily speaking, gradually having less in common with their counterparts on the high seas. For example, marine animals in a closed lake are getting smaller and smaller.

Comparing the size of Lake Paratheis, among other things, to the Greenland ice sheet. Photo: UU.

they change
Smaller sea creatures – including the smallest whales in Earth’s history – initially thrived in Lake Paratheis. But the lake did not have eternal life. In their study, the scientists described how the lake went through several periods of partial drought, with the loss of up to a third of its water. “The water level in the lake is related to three factors: the amount of evaporation, the amount of precipitation, and the supply of the rivers,” says researcher Wout Krijgsman. Scientias. nl. “As it became drier in Europe, less water was likely supplied from rivers.” Because the water continued to evaporate as usual, the water level dropped dramatically. up to 250 metres.

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Toxic environment
It must have had a major impact on the animals that lived in the lake. “The lake was filled with salt water,” says Krijgsman. “As it evaporates, the volume decreases and the salinity increases, creating a bad or even toxic environment for much of the life in that lake.” Researchers believe that most life forms became extinct and that the survivors were sick and disfigured. “It must have been a horrific prehistoric world, a wet, wasteland version of Mad Max.”

Although all this happened millions of years ago, researchers are still able to describe it quite accurately. It’s because of the sediment, says Krijgsman. We have examined the sediment bundles that were deposited on the ancient lake bed. This ancient soil was pushed up by the formation of mountains (eg the Caucasus and Crimea) so that all the sediments of the lake are now at the surface and form the coasts of the beautiful cliffs of the Black Sea. Using magnetic reflections and the fossils found, we were able to date the ancient lake sediments and determine how deep the sediments were deposited.” For example, the researchers first found fossils indicating a depth of 200-250 meters, not far from the fossils of organisms that lived near the coast “From that, we can conclude that the lake has fallen by about 200-250 meters in the water level.”

Where did all this water go?
If the water level in such a large lake drops between 200 and 250 meters, then a huge amount of water will be lost. Where did that water go? Krijgsman believes: “It would have become wetter elsewhere in the world, so that lakes grew there.” “Otherwise you could also dump that water into the sea. If you divide that volume by the global surface of seas and oceans, that could give you a difference of less than an inch.”

It is not clear what was the driving force behind the major and drastic changes in Lake Paratheis. It requires more insight into temperatures and their effect on the lake and the rivers that supply it. The fact that the enormous lake covered many climatic zones does not help. But Krijgsman hopes that in the future it will become clear why the lake has shrunk so much. “We are working on it now. Our next story will be about rebuilding the temperature of both the water and the land.”

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Problematic inland lakes
Thus, Lake Paratheis has not yet been left to researchers. There is a reason; It is important, according to Kriegsman, to explain how this lake—and all who lived in it—succeeded. “For example, it tells us what happens to aquatic life when conditions deteriorate,” he says. This is something that still happens today. “The most extreme examples of problematic inland lakes today are the Dead Sea in Israel which is now extremely saline and uninhabitable (because the waters of the Jordan River are mainly used for irrigation) and arlzy In Kazakhstan, it has almost completely disappeared.

In addition, sediments from the huge lake can be used to reconstruct a crucial period in the history of Europe. “During the same period, drastic changes occurred in the vegetation cover: forests disappear from Europe and with these forests also great apes disappear. There is a fairly new theory that due to the drought in Europe (about 8 million years ago), these monkeys all migrated to Africa where they evolved into the first humans who returned to Eurasia much later (the oldest hominin fossil outside Africa is dated ~1.8 million years ago in Georgia (Dmanisi), and thus lived on the edge of Lake Parathetis’). Thus the sediments left by this huge inland lake do not It can only tell us more about this lake and the animals that lived in it, perhaps even giving us more insight into our evolutionary history.