In 2015, the Copenhagen University geochemistry, Kurt Kjær, discovered a strange depression under the Hiawatha Greenland glacier. A further study shows that what was just discovered was grater more than 30 kilometers wide. Its origin: asteroid.
The crater is only historic through its dimensions, which is one of the largest 25 on Earth. However, the history and origin of what is of interest to science. When and how do we assume a huge impact on the continental ice leaflet in the Groenland?
It seems that it is not so long ago, not at least in terms of the history of our planet since creating a meteorite at least a kilometer in width. As explained by Kjær:
Amazing finds require exceptional evidence. We have more than a decade of radar survey data, a technique to look through the ice, and we build a map of the topography on the glacier. That's how in 2015 we came across the great cyclical depression beneath the tier. We immediately know that this was something special, but at the same time it was clear that it would be difficult to confirm the origin of depression.
Since then, the last three years have been working and studying the area, taking photos and using a new radar developed by the University of Kansas. According to engineer John Paden:
You can see the round structure on the edge of the ice sheet, especially when flying high enough. In general, the crater can not be seen through the plane's window. It's funny that no-one thinks so far: & hey, what is that semi-ambient feature there? & # 39; From the plane it's hard and difficult to see, unless you already know it's there.
Using satellite images taken by a low-angle sun cancellation of the hills and valleys on the ground on the ice sheet, you can actually see the entire crater circle in these images.
Kjær has also explained that the stranger reminds him of the start of an accident in Cape York's feteor in the Groenland about 10,000 years ago, which would be the same thing that left large pieces of iron that was spread out the same region with the glacier, could it be a link to it? event impact?
Recent published works do not conclude that this is the case, but they present multiple multiple evidence lines that suggest the crater is likely during the last 100,000 years.
Geochemical analysis of sediments near the glacier also showed evidence of impact processes, identifying the presence of iron. These included quartz, commonly found in effect zones, and glass, created from silica in the reservoir through the intensive heat effect.
In terms of age, researchers believe that the evidence they provide is strong enough to think it has happened before Iceland covers itself. It's hard to be wrong if we believe that the range covers 3 million years ago to just 12 thousand years ago, towards the end of the last ice age. According to Kjær:
I think it happened when Greenland had been covered in ice and so it would have melted a great deal of water. This melting water will go to the south towards a sensitive point in the climate system.
However, they are currently trying to drill through the ice to obtain samples of the bed that can be used for dating and the exact date of the effect. A crater is as big as the window that it has opened to science. His study raises all sorts of questions, such as the possibility of asteroids or the fact that the effect causes a global cooling event that could have a great impact on older people's populations. [Science, EurekaAlert]