The Earth has only 20 ancient lakes more than one million years old, of which the oldest lake formed 25 million years ago.
It was Baikal, a giant freshwater lake in Southeast Siberia, according to Ted Ozersky, Associate Professor of Research Lake and other domestic waters at the University of Minnesota. The second ancient lake on the planet is Issyk-Kul in Kyrgyzstan, forming about 20 million years ago.
Baikal is the oldest and deepest lake in the world. Image: Janitor
Lake Baikal has an area of 31,700 km2, is the largest lake in the world. This is not only the oldest lake but also the deepest lake with a depth of about 1.6 km. But that is only the depth of water. The area of the pan is much deeper, including 5 – 7 km of sediment on the bottom, according to Ozersky. In the case of Lake Baikal, the researchers surveyed the seismic to estimate the average sediment formation rate.
This sediment is the key to determining the lake date. Researchers are chronic thanks to the method of intentional age of radioactive isotopes – measuring the ratio of radioactive isotopes. In this case, they analyze lake sediments to find radioactive versions of cesium, lead and carbon. The analysis results help reveal the dating of different layers of sediment and sediment accumulation speed.
When understanding the formation of the lake, researchers can better understand how it exists for millions of years. Many lakes formed by glaciers, according to senior scientist Mark Edlund, director of aquatic research and collection at the Minnesota Science Museum. The glacier creates an empty hole in the landscape and leaves ice blocks. This amount of ice then melted, filling the low -lying holes. “In a big context, they are short -lived systems,” Edlund said.
Baikal is a stretchy lake, formed when the two continents began to move separately, creating deep cracks. When these two pieces continue to split, the crack also continues to deepen. “As a result, that area was never filled,” Edlund said. That is why the separation lakes can last for so long.
Ozersky said that Ho Baikal expanded 2.5 cm per year. Some other ancient lakes in the world, such as Malawi lake (5 million years old) and Tanganyika lake (12 million years old) – both in Southeast Africa – also formed from cracks.
Baikal is considered the most biodiversity lake on the planet. “The evolution has had a lot of time taking place in the lake ecosystem without interruption,” Ozersky explained.
The lake also has the highest percentage of endemic plants and animals – species that do not live anywhere else on Earth. The most prominent among them is probably the baikal seal (Capica Box), the only freshwater seal. Some other seals can live in lakes, but they have “invaded” lakes from rivers and streams, Ozersky noted. Lake Baikal is also the residence of hundreds of freshwater shrimp species, giving scientists the opportunity to study the formation of species and diversify.
Edlund studied sand algae, a single algae. These organisms take silica dissolved from water and turn into biological glass, surrounding them. Sand algae usually has a diameter of 10 – 50 micrometers (about half of the width of human hair), but the sand algae in the abnormal large baikal, about 50 – 150 micrometers. “When observing algae in Lake Baikal, they really surprised you,” Edlund commented.
The average surface temperature of the Baikal lake is only 4 degrees C. “It is a cold lake. If you want to swim in it, you must prepare mentally,” Edlund said.