Baltic Shield

The Baltic Shield, sometimes referred to as the Fennoscandian Shield, is located in Fennoscandia (Norway, Sweden and Finland), northwest Russia, northern Denmark and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton. It is composed mostly of Archean and Proterozoic gneisses and greenstones which have undergone numerous deformations through tectonic activity (see Geology of Fennoscandia map [1]). The Baltic Shield contains the oldest rocks of the European continent. The lithospheric thickness is about 200-300 km. During the epoch, great continental ice sheets scoured and depressed the shield's surface, leaving a thin covering of glacial material and innumerable lakes and streams. The Baltic Shield is still rebounding today following the melting of the thick glaciers during the Quaternary Period.

The Baltic Shield is divided into five provinces: the Svecofennian and Sveconorwegian (or Southwestern gneiss) provinces in Fennoscandia, and the Karelian, Belomorian and Kola provinces/cratons in Russia. The latter three are divided further into several blocks and complexes and contain the oldest of the rocks, at 2.5–3.4 Ga (billion years). The Vodlozero block in south-eastern Karelia has been dated to 3.4 Ga. The youngest rocks belong to the Sveconorwegian province, at 900–1700 Ma old. Sometimes included as part of the Baltic Shield is the East European Platform (or Russian Platform), an area of western Russia covered by 3 km of sedimentary rock.

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