Quirky ice platforms on Lake Baikal

In our regions you sometimes come across stones, leaves and branches on frozen water that are in a hollow, as if they had sunk under your own weight. The impression is deceptive. Rather, they absorb direct solar radiation and therefore warm up to above freezing point. If the temperatures are not too low, meltwater is created first and then, with its evaporation, a perfectly fitting trough is created, which becomes deeper and deeper with prolonged exposure to the sun. The ice itself is largely transparent and absorbs little solar energy. So it is hardly attacked on unspoiled areas in the area.

Sometimes, however, the opposite can be observed, for example with long-lasting low temperatures on snow-free, frozen lakes such as Lake Baikal in Siberia. There stones are also surrounded by a hollow, but instead of lying in it, they rather seem to float above it. In fact, they are supported by a narrow ice platform that protrudes from the depression. Because of the visual similarity to stone towers used for meditation, such finds are sometimes referred to as Zen stones.

The contour of the Zen stones is reminiscent of mushroom-like rock formations, such as can be admired in Turkish Cappadocia. Such “fairy chimneys” are created when the harder rock lying on the softer shields in some places and thus delays the erosion caused by water and wind.

It was already known that erosion also played an essential role in the formation of the Zen stones. So far, however, it has not been possible to explain which mechanism erodes the ice so much at such low temperatures. Because, on the one hand, the direct sunlight is very weak due to the season and, on the other hand, the structure of the Zen stones takes place regardless of whether and from which direction the sun is shining.