Baltica

The continent of Baltica (green) existed from the Late Proterozoic to the Early Palaeozoic and included what is now the East European craton of Northwestern Eurasia. Baltica was created as an entity not earlier than 1.8 Ga. Before this time, the three segments/continents that now make up the East European craton were in different places on the globe.

Laurentia is shown in red, Siberia in peach, embryonic Gondwana is yellow, Australia-East Antarctica grey.

The Baltic Shield (Fennoscandian Shield) now forms the continental core of Europe. The shield is composed of the oldest Precambrian crystalline rock in Europe (Archaean and Proterozoic gneisses and greenstone deformed by rounds of ancient tectonic activity.)

The tectonically stable shield region was unaffected by the Caledonian, Hercynian, and Alpine orogenies, though mountains rose at shield margins. The Baltic Shield is exposed in Finland, Sweden, and Norway as a result of scouring by continental ice sheets during the Pleistocene epoch.

[ more on Baltic Shield ]

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Laurentia

Laurentia, or the Laurentian Shield, or the Canadian Shield is the geological term for the North American Craton.

The North American Craton (brown) has comprised a portion of a series of supercontinents, and has remained stable for about 600 million years. This cratonic region comprises a basement of Precambrian metamorphic and igneous rock, exposed in the north as the Canadian Shield, and covered by a relatively thin cover of younger sedimentary rock on the Interior Platform.

The geologically stable rocks of the cratonic core are surrounded by deformed rocks (purple) and more recently deposited sedimentary material (green). Compare to bedrock of North America.

Maps of North American rock types : rock types - metamorphic, plutonic, sedimentary, volcanic; tapestry of time and terrain, terrain.

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