The Russian Part of the Baltic Crystalline Shield: Recent Uplift of One of the Earth’s Most Ancient Massives

A general overview of the landforms of the Baltic crystalline shield was made; geologic, tectonic and geomorphological processes which created the modern landscapes were analyzed. The Baltic crystalline shield, composed by Archaean and Proterozoic rocks, is among the most ancient massives on Earth. It has seen numerous periods of tectonic activation, folding and faulting since the Precambrian time, which left numerous veins and intrusions with extreme diversity of minerals. In the Neotectonic time, the existing faults were re-activated and new ones were set, resulting in intense movements of crustal blocks. During the Quaternary, the Baltic shield was covered by ice sheets for several times. The ice left numerous moraines, glacial striae and fluvioglacial landforms. The last glaciation ended by 10–11 ka, and uplift of the Earth’s crust driven by glacioisostatic adjustment (GIA) started. The rates of this uplift exceeded the eustatic rise of the World Ocean from meltwater input. Because of this, the eastern part of the Russian territory within the Baltic Shield experience a relative sea level (RSL) fall in the Holocene. Although the general uplift of the Earth-s crust in the last millennia was GIA-driven, local tectonic block movements of the Earth’s crust were imposed on this general uplift, creating scatter in the RSL data. Such movements along major faults left numerous traces of ancient earthquakes. The combination of ancient resistant intrusive and metamorphic rocks, long-term uplift, past glaciations and high tides of the White Sea created the unique landscapes of the Baltic Shield with its rocky benches, skerries and sheepback rocks, meromictic lakes in former sea gulf which will later become isolation basins, series of uplifted coastal bars of well-rounded boulders and large tidal flats with boulders displaced by sea ice.