Unexplained 'ice circles' appear on remote Russian lake

A couple of mysterious circles have appeared in the ice covering Russia's remarkable Lake Baikal. (Wired) Were the circles made by alien spacecraft studying the lake? Baikal would make an interesting study.

Lake Baikal is the world's largest lake by volume (it's not that big around, but it's a mile deep), holding 20 percent of the world's fresh water (more than all the Great Lakes combined). Of the 2,000 species of life in Lake Baikal, two-thirds can't be found anyplace else on Earth. (World Wildlife Fund) And at 25 million years old, Baikal is one of the planet's oldest lakes.

According to the Wired article, the likely cause of the circles isn't extraterrestrial, but geothermal. Perhaps an "upwelling of warmer water in the lake." But what has scientists stumped is that the southern circle appears over the deepest, coldest part of the lake.

Here's a close up of one of the circles…

And a wider shot of both…