Southeast Siberia is home to the world’s oldest lake, with scientists estimating that the massive body of water dates back 25 million years. As well as being the world’s oldest, Lake Baikal , which stretches 31,700 square kilometres, is also the deepest lake in the world, with a water depth of around 1.6 kilometres. However, according to Ted Ozersky, an associate professor of biological limnology at the University of Minnesota, the lake’s basin is “much more than a mile deep,” Live Science reports.
The lake has between five and seven kilometres of sediment that is built up at the bottom, which researchers have used to date the formation of the lake. A lake’s age is measured through isotopic dating – a technique where the ratios of radioactive isotopes are measured. Regarding Lake Baikal, the limnologists analyse lake sediments for radioactive versions of cesium, lead and carbon, which reveals how old the different layers of sediment are and how fast the sediment builds up, as per Ted Ozersky.
With this improved understanding of lake formation and the world’s oldest one specifically, the researchers can get a better idea of how it managed to sustain for millions of years. Lakes usually form as glacial features, but “in the grand scheme, they’re very short-lived systems,” senior scientist and the director of aquatic research and collections at the Science Museum of Minnesota, Mark Edlund explained to Live Science.
However, this incredible lake, in particular, is a rift lake. This means that Lake Baikal formed as a result of two continental plates started moving away from each other, creating a chasm called a graben.
As the plates continue to move apart, they continue to deepen and “as a result, that site never fills in,” which is how the world ends up with rift lakes that can last so long. Other examples of rift lakes include Lake Malawi, which is up to five million years old, and Lake Tanganyika, which is up to 12 million years old.
Another feature that makes it special is its biological diversity. The lake’s ecosystem houses plates and animals that aren’t found anywhere else in the world, including the Baikal seal – the only freshwater seal species. Although other seal species may inhabit lakes, those seals have “invaded” them through streams, Ted Ozersky explained.
It also hosts hundreds of species of freshwater shrimp, which gives researchers the opportunity to study speciation and diversification. “Trying to understand how evolution works is one thing that is really interesting about Baikal,” Ozersky said.
The lake is open to visitors. However, it isn’t a great spot for swimming as for five months out of the year, it gets covered with ice as well as the fact that the average temperature is 4C, so anyone who does must brave the bitter cold.
