Bratislava, 30 August 2023: Millions of years ago, the Turiec valley was a lake a few dozens of metres deep, surrounded by rolling hills which were significantly different from today's Malá and Veľká Fatra mountain ranges. The disappearance of the lake led to the formation of the Váh river catchment. A new method was used for the first time to establish the age of this ancient lake. The research paper whose lead author is geologist Michal Šujan from Comenius University, was published in the Palaeography, Palaeoloclimatology, Palaeoecology journal.

30. 08. 2023 09.39 hod.
By: CU External Relations Office

The lake that filled the Turiec valley in the Tertiary was land-locked and far from the ancient Pannonian Basin System. It had no significant rivers flowing out of it and its banks included wetlands, humid forests and low hills. The past existence of a lake in the valley is evidenced by sediments which include fossils of molluscs and water plants that have intrigued geologists for decades. So far, however, traditional methods were unable to prove the existence of a lake in the Turiec basin. "We applied a novel dating method using cosmogenic beryllium from the atmosphere, which ends up in rivers and seas as a result of rain and is deposited on the surface of grains in sediments. Knowing its radioactive half-life, we can calculate the age of the deposits. The method has great potential, because it can be used to analyse silt mud, the most common sediment on Earth," says Michal Šujan from the Faculty of Natural Sciences of Comenius University, where the relatively new dating method is being developed.

The authors of the research paper estimate that Lake Turiec existed between 10.7 and 6.7 million years ago. It disappeared about 6.7 million years ago when the Malá Fatra mountains lifted up. Sand and gravel washed from the mountains filled the lake and led to the creation of the Váh river catchment as we know it. The study of sediments in the valley also allowed a glimpse into the development of the Western Carpathians.  "The sediments deposited in the paleo-lake document the landscape character of the Western Carpathians and their gradual uplift. Between 10.7 and 6.7 million years ago, when the Turiec Lake was in existence, the Tatry mountains and Nízke Tatry mountains did not yet exist as significantly elevated mountain ranges. If that was the case, sediments from them would fill up the lake earlier, hastening its disappearance," adds Michal Šujan. 

The research was carried out by an international team of researchers from the Faculty of Natural Sciences of Comenius University, the Slovak Academy of Sciences, the Slovak National Museum, France and Croatia. It is unique because the subject is not studied by any other research labs in the world.

The research was supported by the Slovak Research and Development Agency through grants APVV-16-0121 and APVV-20-0120 and the Research Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and the Slovak Academy of Sciences (VEGA) under grant 1/ 0346/20.