Exploring the massive ice sheet in West Antarctica, a team of geologists has discovered the remains of an ancient river system that flowed millions of years ago for approximately 1,500 km.
The discovery offers a glimpse into Earth's history and hints at how extreme climate change could change the planet.
According to their findings, which were published in the journal Science Advances, a team of researchers on a research expedition led by the Alfred Wegener Institute revealed a hidden secret lurking under the ice of Antarctica, where they found evidence of the existence of an ancient river system by studying sediment samples. From the Amundsen Sea.
This suggests that Antarctica had a temperate climate about 34 million years ago, where dense forests flourished and a vast network of rivers wound their way across the landscape.
The Earth went through a dramatic cooling period between 34 and 44 million years ago. This period, the mid-to-late Eocene, saw a sharp decline in carbon dioxide levels, leading to the formation of the first glaciers on ice-free Earth.
Scientists have long wondered how this event occurred in Antarctica, a continent now dominated by ice.
Antarctica was not a single continent at that time. Until about 100 million years ago, it was part of a huge continent known as Gondwana. As Gondwana broke up, Antarctica moved south and created its own continent.
Although it moved to the Antarctic, Antarctica experienced moderate climatic conditions until the end of the Eocene era, about 34 million years ago.
The new study included an international team of researchers studying minerals and rock fragments found in sediment samples from the Amundsen Sea off the west coast of Antarctica.
The samples were collected during an expedition aboard the research icebreaker Polarstern.
Surprisingly, most of these metals and fragments came from somewhere other than West Antarctica, where they were found.
Instead, the samples point to a distant source: the Trans-Antarctic Mountains on the other side of the continent, thousands of kilometers away.
According to a press release, this mountain range was not always so tall. However, it has been growing gradually since the late Eocene.
This rise is linked to a geological feature called the West Antarctic Rift System. This division separates the continent of Antarctica into two geographical blocs: East and West.
So, how does all this relate to the ancient river?
The uplift of the Trans-Antarctic Mountains has created a huge amount of erosion debris, which consists of impacted and moved rocks and minerals.
The newly discovered river system likely transported this debris a long distance (about 1,500 km) across the West Antarctic Rift System before it was deposited in the Amundsen Sea.
Professor Cornelia Spiegel from the University of Bremen said: “The existence of such a transcontinental river system shows that, unlike today, large parts of West Antarctica must lie above sea level as broad, flat coastal plains.”
According to the press release, West Antarctica had low terrain at the end of the Eocene. Although located in Antarctica, West Antarctica was not cold enough for permanent ice sheets to form due to its low elevations.
In contrast, the mountainous regions of East Antarctica, which had higher elevations and lower temperatures, were already witnessing the beginnings of glaciers at that time.
Wonderful!
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