The Kuznetsov bros.’ expedition to the Polar Urals

The article is dedicated to the geological results of a comprehensive expedition to the Polar Urals, sponsored by brothers N. G. and G. G. Kuznetsov and organized by the Imperial Academy of Sciences, Geological Committee, and Russian Geographical Society from May 22 to September 9 (old style) of 1909, as well as to the 140th anniversary of the head of the expedition, the outstanding petrographer O. O. Backlund. The expedition faced the wide distribution of metamorphic rocks. The guiding ideas and methods of reconstructing their primary (sedimentary or magmatic) nature used by O. O. Backlund are of great historical interest. Besides, the article draws attention to the problem of rational classification of rocks, which has not been solved so far.