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The lakes of Dalarna from space, the largest of them is the Siljan
Photo: NASA
It doesn't get much more Swedish: In the rolling hills of Dalarna, the forests are repeatedly interrupted by agricultural areas and comparatively small towns.
The typical red shade of Swedish wooden houses, the Falun red, comes from here.
The Dala horses, beautifully painted wooden horse figures, which are also made in the region, are also world-famous.
And then there are the lakes.
The largest of them is the Siljan.
With an area of around 290 square kilometers, it is more than twice the size of the Müritz, for example, the largest lake located entirely in Germany.
Fun fact: On the ranking list in Sweden it is still only enough for the Siljan for seventh place.
What is remarkable, however, is its depth of up to 134 meters - although that is not enough for the top spot, as the northern Swedish Hornavan occupies.
The area was heavily glaciated
Its history is special on Siljan: the landscape of the lake and its surroundings were not always so calm.
They were shaped by a gigantic meteorite impact a long time ago.
Exactly how big the body was that crashed onto our earth at that time cannot be clearly stated.
But it must have been several kilometers in diameter.
If you know about the impact, then you can clearly see the area where the impact occurred around 370 million years ago on the image of the US satellite "Landsat 8".
The round, water-filled structure is not directly the crater.
The forces of erosion have actually made it disappear over the course of millions of years.
The hole created by the impact was filled with sedimentary rock, and the mountains at the edges were gradually removed by wind and water.
However, the region was massively glaciated during the last ice age, which ended around 10,000 years ago.
And these glaciers simply planed away the soft rock that had filled the crater for a long time.
When they disappeared, the Dalarna Lakes formed.
In addition to the Siljan, these included the small bodies of water Orsasjön, Skattungen and Ljugaren.
Traces of life at a depth of 500 meters
The Vredefort Crater in South Africa is considered to be the largest unequivocally proven impact crater on earth.
It was once 320 kilometers long and 180 kilometers wide.
Because the catastrophe that led to its formation was probably two to three billion years ago, it has also become significantly smaller due to erosion processes.
Today it measures around 50 kilometers, which is comparable to the remains of the Siljan crater.
In the 1980s, natural gas had been drilled on the Siljan.
But the hole, which is almost seven kilometers deep, did not bring any spectacular finds.
Nothing was found in a further 6500 meter borehole that was sunk later.
In contrast, large deposits of lead and zinc are known in the region.
Research is still going on in the Dalarna underground.
It is about fundamental questions.
Investigations into how attractive the conditions in the crater were for the reintroduction of microorganisms could have implications for the search for life on other celestial bodies.
Another specialist article published this year with data from a borehole on the Siljan shows the extreme conditions under which life can - or could - thrive on our own planet.
In it, researchers reported fossilized remains of mushrooms that they found in the drill core - at a depth of 500 meters.
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