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  2. Shield (geology) - Wikipedia

    en.wikipedia.org/wiki/Shield_(Geology)

    A shield is that part of the continental crust in which these usually Precambrian basement rocks crop out extensively at the surface. Shields can be very complex: they consist of vast areas of granitic or granodioritic gneisses , usually of tonalitic composition, and they also contain belts of sedimentary rocks, often surrounded by low-grade ...

  3. List of shields and cratons - Wikipedia

    en.wikipedia.org/wiki/List_of_shields_and_cratons

    A craton is an ancient part of the Earth's continental crust which has been more or less stable since Precambrian times. Cratons whose ancient rocks are widely exposed at the surface, often with relatively subdued relief, are known as shields.

  4. Canadian Shield - Wikipedia

    en.wikipedia.org/wiki/Canadian_Shield

    The Canadian Shield (French: Bouclier canadien [buklje kanadjɛ̃]), also called the Laurentian Shield or the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the ancient geologic core of the North American continent.

  5. Continental crust - Wikipedia

    en.wikipedia.org/wiki/Continental_crust

    Continental crust is the layer of igneous, ... There was relatively rapid development on shield areas consisting of continental crust between 3.0 and 2.5 Ga. ...

  6. Continent - Wikipedia

    en.wikipedia.org/wiki/Continent

    A craton typically consists of a continental shield surrounded by a continental platform. The shield is a region where ancient crystalline basement rock (typically 1.5 to 3.8 billion years old) is widely exposed at the surface. The platform surrounding the shield is also composed of ancient basement rock, but with a cover of younger sedimentary ...

  7. Geology of North America - Wikipedia

    en.wikipedia.org/wiki/Geology_of_North_America

    The earliest part of the shield is metamorphosed Archean rocks, originally volcanic in origin. Numerous terranes were accreted onto this Archean core during the Proterozoic to form the Canadian Shield. [4] The southern Archean province is the Superior Craton, it is formed by the combination of a greenstone-granite and a gneiss terrane. [5]

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  9. Baltic Shield - Wikipedia

    en.wikipedia.org/wiki/Baltic_Shield

    The Baltic Shield (or Fennoscandian Shield) is a segment of the Earth's crust belonging to the East European Craton, representing a large part of Fennoscandia, northwestern Russia and the northern Baltic Sea. It is composed mostly of Archean and Proterozoic gneisses and greenstone which have undergone numerous deformations through tectonic ...