In our time, Antarctica is a continent completely covered with ice with extremely low temperatures. However, it was not always so cold – tens of millions of years ago the temperature on the planet was much warmer than it is now. At that time, the continent was covered with forests, dinosaurs, various birds and other animals lived on it. And even in the mid-late Eocene era, that is, 44-34 million years ago, the continent was not completely covered with ice. Moreover, the rivers passed through the entire continent, which means it did not have an internal sea.
Millions of years ago, Antarctica was covered with forests and had many rivers
Why was it warm in Antarctica
As mentioned above, despite the current global warming, there have been much warmer periods on Earth. The difference was especially noticeable in Antarctica. For example, 90 million years ago, conifers, ferns, flowering plants and other flora and fauna grew on the continent. Also, earlier scientists found that 50 million years ago, giant birds lived in Antarctica, which scientists called “terror birds.”
One of the reasons for the warm climate in Antarctica was that ocean currents carried warm water from the equator and washed the perimeter of the continent with it. Subsequently, these currents were blocked by the Antarctic Circumpolar Current, which is also called the Western Wind Current. This is a cold surface ocean current with a length of up to 30 thousand kilometers and a width of up to 2.5 thousand kilometers.
Before warm water stopped washing Antarctica, the highlands of the continent had an ice cap, and lush forests grew in the lowlands, which were covered with snow in winter. The presence of forests on ancient Antarctica indirectly suggests that the continent had an abundance of large rivers, since they needed rain, which comes from rivers.
Research vessel Polarstern in the Amundsen Sea. Photo source: iflscience.com
Antarctica had mountain rivers
Drilling through the ice that has accumulated in Antarctica for millions of years to take soil samples is a difficult task. Therefore, researchers from the University of Bremen decided to do something different. They drilled into sedimentary rocks near the coast, namely — in the Amundsen Sea. The icebreaker Polarstern was used to remove the ice.
As a result, scientists discovered a layer of mineral deposits up to 24 meters thick, as the authors of the work report in the journal Science Advances. The mineral composition is very different from those found in nearby areas of West Antarctica. According to researchers, they were transported from the Transantarctic Mountains, which divide Antarctica into two parts. That is, the ancient river flowed from the mountains and flowed into the Amundsen Sea. This means that its length was about 1,500 kilometers or even more if it meandered.
I must say that this is not such a big figure in modern times. For example, the length of the Amazon is 7100 km, and the Nile is 6670 km. The Lena River, the longest river in Russia, is 4,400 km long.
The most likely route of an ancient river in Antarctica
As the researchers themselves say, the existence of such a large river system is evidence that forty million years ago the west of Antarctica, or at least most of it, was above sea level. The landscape was predominantly large and flat plains, otherwise the river would not have been so long.
It should be taken into account that at that time the sea level was much higher, since there were no such massive glaciers as today. This means that at that time West Antarctica was higher than it is now. But at the same time, they were low enough that glaciers did not form on them.
Soon Antarctica will again get rid of glaciers
When in Rivers stopped existing in Antarctica
As researchers report, sediments stopped accumulating in the Amundsen Sea 34 million years ago. Most likely, this happened due to the constant glaciation of the continent. The processes as a result of which Antarctica acquired its current appearance began 44-40 million years ago.
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It must be said that Antarctica is currently actively losing glaciers, and sooner or later it will completely get rid of them. Moreover, this will happen regardless of greenhouse gas emissions. However, there will never be such a river in Antarctica again, given the changes in the landscape that have occurred.