Unusual (ice?) formations in the area of the Vneshniye ostrova of Finnish bay

Abstract

When carrying out complex expeditions of the Russian Geographical Society within the archipelago of the Vneshniye Ostrova (Outer Islands) of the Gulf of Finland, fundamentally new geological objects were found, that were not previously known, some of them were identified as secondary quartzites, others whose nature is debatable are discussed in this article. On the island of Moshchnyj greeted boulders with a destroyed upper hemisphere. The nature of the destruction resembles the structures known as the Cone of Destruction or Shatter Cone, which in some cases are the only indicators of a meteorite nature for some ring structures. Three options for the formation of destroyed boulders are discussed: external meteorite impact similar to the structures of the Shatter Cone type, as a result of an endogenous explosion followed by coffered collapse of fragments of deep rocks and the main version is the fall of large boulders from a vertical glacier cliff and their impact on the underlying boulder, which under the influence of impact cracks. A similar situation is possible within the regional part of the cover glacier, which was located in the area of the future Island of Moshchnyj and known as the Neva end moraine with age of the 12000 years.