How do you know the composition of the Earth’s atmosphere millions of years ago, if we can’t actually go back to the exact period? Scientists have found a way to do this some time ago.
The answer lies in the ice core, in this case from Antarctica’s Aung Valley. The authors of the studies who used these samples described their achievements in Pages cryosphere. They explained why they chose to dig in this area and what they hope to learn from studying ice cores.
How does this approach work? It’s about air bubbles trapped in the ice. Caged in such sterile conditions for millions of years, they could be a perfect opportunity to learn about Earth’s atmosphere at that time. So far, most of the core parts have been taken from sites in the eastern part of Antarctica, but now scientists have decided to change tactics a bit.
They focused their attention on the regions within the Aung Valley in the trans-Antarctic mountains. These separate East and West Antarctica. The ice in the Aung Valley was deposited there due to the glaciers that slipped from the mountains. When its upper layers melted, protection was provided by the layers of rock that protected the ice below. Earlier, researchers suggested that the ice beneath it may have been 5 million years ago. This means that they are not only older than those in the east, but also thinner, which makes drilling and extracting cores easier.
Drilling was carried out in 2017 and 2018 and resulted in the extraction of a 9.5-meter core. Preliminary studies of the contained isotopes indicate that the ice ages range from 3 million to just over 5 million years old. These include isotopes of neon, aluminum and beryllium, which can be used to test their age because they were formed by cosmic rays colliding with the rocks above. In addition, the study authors concluded that the ice sheet under the rocks consists of two plates stacked on top of each other. So the two icebergs were in the same place, separated by millions of years.
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