In 1949 geologist Vadim Kolpakov discovered a large mound of limestone in the north of the Irkutsk region in Siberia. The cone is curiously shaped with a crater at the top and a small mound in the center.
Since the discovery of the crater, there have been many theories as to what could have created it. For a long time it was believed to be a meteorite impact structure. But the Patomskiy crater does not resemble any other known meteorite site. Later, some geologists suggested that it could be a nascent volcano, but no volcanic material has ever been found either.