It is clear from Baltic endemic fossils in Novaya Zemlya that the islands have been part of Baltica since the Early Palaeozoic, whereas the Taymyr Peninsula farther east was part of the passive margin of Siberia in the Early Palaeozoic. Northern Taymyr, together with Severnaya Zemlya and parts of the crust of the Arctic Ocean, formed the Kara Terrane. The Urals Mountains formed in the mid and late Palaeozoic when Laurussia collided with Kazakhstania, a series of terranes. The eastern margin, however, originally extended farther east to an active margin bordered by island arcs, but those parts have been compressed, fractured, and distorted especially in the eastern Urals. The early Palaeozoic eastern margin is better preserved south of the polar region (65 °N) where shallow-water sediments can be found in the western Urals whilst the eastern Urals are characterised by deep-water deposits. The oldest known mid-ocean hydrothermal vent in the south-central part of the Urals clearly delimits the eastern extent. The straightness of the mountain chain is the result of continuous strike-slip movements during the Late Carboniferous to Early Permian (300–290 Ma). Baltic endemic faunas from the Early Ordovician have been found in Kazakhstan near the southern end of the eastern margin, or the triple junction between Baltica, the Mangyshlak Terrane, and the accretionary Altaids. Here the Early Palaeozoic rocks are buried under the Caspian Depression. See also References Notes Sources Historical continents Plate tectonics Proterozoic Paleozoic Natural history of Europe