Traces of Ancient River That Once Dominated Antarctica 34 Million Years Ago
Scientists have discovered that a river similar in size to the Rio Grande once dominated West Antarctica, offering a rare glimpse of the continent's land mass that is now covered in ice.
It is believed that the river flowed about 44-34 million years ago, just before the thick ice sheets of the continent began to form. At that time, after the dinosaurs and long before human life, Antarctica had a mild climate and likely hosted giant penguins.
This implies that at that time, West Antarctica was above sea level as before West Antarctica was covered by ice, it was dominated by a large river system, had a temperate climate (with surface water temperatures of about 19°C in summer), and a swampy environment. The river presumably meandered through a vast coastal plain with marshy wetlands along its banks.
The river was discovered after analyzing sandstone samples from beneath the Amundsen Sea Embayment, where the West Antarctic Ice Sheet meets the ocean. In this rock, dating back to the Eocene—a geological period that lasted from about 56 million to 34 million years ago—scientists found evidence of sediments originating from the Transantarctic Mountains, indicating that they had been washed there by an ancient river. Traces of organic chemicals associated with freshwater bacteria were also found, further supporting the presence of a large river delta in the region. The river extended between the Transantarctic Mountains and the West Antarctic Ice Sheet, flowing into the Amundsen Sea.
The great Antarctic glaciation began during the Eocene-Oligocene transition [when the planet experienced a period of intense cooling] 34 million years ago, marking one of the most pronounced climate transitions of the Phanerozoic [from 538.8 million years ago to the present].
