A giant river system tens of millions of years old was discovered under the Antarctic ice. Photo.

In the middle of the Late Eocene, 44-34 million years ago, much of Antarctica was free of ice, creating space for river systems that are now long frozen. Sediments from the Amundsen Sea have traveled all the way from the mountain range that covers the continent, confirming the theory that there was no inland sea.

Scientists have determined that when part of Antarctica was free of ice, rivers should have existed there, but now the size and time of one of them has been determined. In general, 40 million years ago, the world was a hotter place, but in this location, the temperature difference was significant. The research results were published in Science Advances.

Large ocean currents carried warm water away from the equator until the formation of the Antarctic Circumpolar Current blocked their path. The highlands were covered with glaciers, and the lowlands were covered with snow in winter, so nothing prevented the spread of forests.

Forests need rain, and regular rain means rivers, but it's difficult to determine where they flow. Since the onset of the Ice Age, there has been enough time for the landscape to change. So, you can just look at the current topography of the land and assume that the water flowed to what is now the lowest point.

Drilling through all this ice to find out what it was like once is a daunting task, but Professor Cornelia Spiegel of the University of Bremen and her colleagues have found an easier way to identify Antarctica's lost rivers. They drilled through sediments around the coast using the icebreaker Polarstern.

In the Amundsen Sea, the team found 17-24 meters of sediments consisting of minerals that do not match those of neighboring West Antarctica. Instead, they come from the Transantarctic Mountains, which separate West and East Antarctica. No fossils have been found in these sediments that would indicate the ecosystem of that era.

These mountains cross the continent, but this crossing is at right angles to the line from the South Pole to the Amundsen Sea. For the minerals to have gotten there in the Eocene, they would have had to have been brought by a river 1,500 kilometers (932 miles) long, or more if it was winding. Such a length could have dominated West Antarctica, which then, as now, was much smaller than its eastern part.

"The existence of such a transcontinental river system shows that - unlike today - large parts of West Antarctica must have been located above sea level as large flat coastal plains," said Cornelia Spiegel.

The experts concluded that a series of events, including the deposition of sedimentary rocks in the Amundsen Sea, a combination of magma formation, seabed formation, and the rise of the Transantarctic Mountains, began at about the same time: 44-40 million years ago. After that, the region was relatively tectonically calm for about 40 million years. Sedimentary rock deposition could have stopped 34 million years ago with the onset of permanent glaciation or with the appearance of the sea closer to the mountains.

Only verified information is available on the OBOZ.UA Telegram channel and Viber. Do not fall for fakes!