Platform Basement
The most distinguishable physiographic aspect of the East European craton is the extensive 3-km and more-thick Riphean (middle to late Proterozoic) sedimentary cover over its 3000-km-wide platform area (East European Platform, EEP, also formerly known as the Russian Platform) . This is in sharp contrast to the exposed northwest portion of the Baltic Shield, and the Ukrainian Shield in the southwest. The lithospheric thickness also varies widely from 150–200 km in Ukraine to 120 km in southern Russia to over 250 km thick in the NE Baltic Shield, with extremely wide thickness fluctuations of the crustal layers. A shield in any craton is the area of exposed crystalline crust while the other part of the craton is the “platform” where the crystalline crust or basement is overlaid by younger sedimentary cover. Thus the crustal segments of the East European craton comprise both the Baltic Shield and the Ukrainian shield, and the sedimentary platform basement.
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—Henry David Thoreau (1817–1862)