Intricate-shaped black lichens destroy the rocks. Behind the growing front of a lichen the stone surface become jaged and a certain layer of the stone gets removed together with the lichen itself, and so a light-coloured free stone surface becomes exposed again and can be again occupied by lichens of the same species.
An ancient moraine closing the cirque of the sources of the rivulet descending southward from the the Yuzhno-Chuiskii mountain range between the Chikty and Akbul Rivulet, 2600 m above sea level, the upper Dzhazator River basin, Kosh-Agach District, Altai Republic, West Siberia, Russia. 11th July 1998. O. Kosterin.