One of the five largest known floods in the history of the world occurred in the Suwaji region thousands of years ago. Its impact is still visible today. The breakthrough discovery made by scientists from Nicolaus Copernicus University changed the way people think about the landscape of Central Europe and explained in particular: the origin of Lake Hancha.
15-17 000 years ago, during the ice age, one of the five largest floods known in the history of the earth crossed the Suwałki region today. The source of this water is melting ice sheets. The flood transported 2 million cubic meters of water every second. The average flow of the Biamasun River is 10 times more than the average flow of the Vistula River into the Baltic Sea by 2,000 times. Such floods may have only lasted for a dozen days or so, but their effects are still visible in Central Europe, including northeastern Poland.
Researchers from Nicholas Copernicus University in Torun announced this fact to the world on the page of “Earth Science Review” (https://www.sciencedirect.com/science/article/pii/S0012825219300479): Therefore, we can observe certain geological structures in the Central European landscape in a completely different way.
“This research provides new ideas for the establishment of the Polish valley system”-told Dr. PAP. Professor Piotr Weckwerth UMK, the first author of the publication. As he added, the study also explained the origin of other issues Hańcza-Poland’s deepest lake.
Thousands of years ago, the Scandinavian icefields retreated from today’s Poland. The amount of accumulated ice is unimaginable: in its central part, the thickness of the ice layer is 2-3 km, and at the edge, the thickness of the ice layer is 250-300 meters.
The unique landscape location of Suwałki area was affected by the huge glacial flood. Source: Piotr Weckwerth, Wojciech Wysota
It can be assumed that the ice covers a large area north of Poznan, Szczyno and Suvac. When this ice sheet melts, sometimes lakes are formed under or on the ice, which accumulate for a long time.
The floods in Suwałki area today may have occurred when the bottom of one of the huge lakes on the glacier was blocked. Water began to flow from him at an extremely fast speed. “Such a lake may be about 30 kilometers in diameter”-said the professor. Piotr Weckwerth (Piotr Weckwerth).
According to the findings of Nicolaus Copernicus University scientists, the place where water flows from the surface of the ice sheet to its bottom and further into the foreground is Hańcza Lake-the deepest lake in Europe. Another author of the study, the professor, said: “Here, you can see traces of strong erosion under the ice caused by water, which forcefully cut the ground and eject materials out of the ice sheet.” Wojciech Wysota.
During the flood, the area was submerged by floods with a depth of more than 20 meters and a speed of more than 55 kilometers per hour. The scientists explained that the water stretched southwest along the iceberg system-first to Biebrza in Naie today, then to Germany, the North Sea, the English Channel, and the Bay of Biscay. (Then the North Sea and the English Channel are not hidden underwater, but land).
Wrinkles in front of the glacier
This huge flood thousands of years ago was discovered by accident. “I was browsing Geoportal, and elsewhere, the relief lidar images. The Suwaki area caught my attention. Suddenly I learned something: I saw a form similar to the familiar form-Wysota.
As he explained, at the bottom of the river, sometimes-for example in the sand-characteristic ripples of a few centimeters-so-called maturity marks. When he checked the lidar images of the area south of Lake Vigri, he saw similar shapes in the reliefs, but the shapes were much larger: each wrinkle was as high as 8 meters. This means that a lot of water used to flow in this way.
Professor Wysota knows how to explain the existence of such huge ripples based on the latest research: similar forms have been observed in Washington State or Altai in the United States. There, they were described in detail and it was shown that they were caused by huge glacial floods. This means that we are also experiencing similar floods in parts of Europe.
By analyzing the parameters of these wrinkles, scientists were able to determine how much water must flow in this way and how the flooding in the area proceeded. The confusion began to merge.
Dr. Hab, Piotr Weckwerth (Piotr Weckwerth) said that until now, the origins of the Warsaw-Berlin and Torun-Eberswartzka ice margins—the latitude depressions of Poland and Germany—have been a secret. “The iceberg system must be caused by a large amount of water flow. But no one knows its source. The evidence we provided shows that this is a large-scale catastrophic glacial flood, and the water collected in the lake on the surface of the glacial lake flows into it. They gave it. A lot of water forms a network of valleys and ice valleys.”-He said.
Examples of large parks in southern Suwałki and the Wigry Lake area. Source: Piotr Weckwerth, Wojciech Wysota
He added that there is evidence that this type of flooding from ice sheets also reoccurs and reoccurs in other parts of northern Poland in a cyclical manner.
As part of the NCN OPUS 16 grant, Dr. Hab. Piotr Weckwerth and his team will conduct a more detailed study of this glacial flood that occurred during the Pleistocene.
PAP-Polish Science, Ludwika Tomala
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