The Lower Palaeozoic margins of Baltica

The palaeocontinent of Baltica was palaeobiologically and geographically is olated in the early Ordovician, but drew closer to other palaeocontinents a s the Ordovician progressed, colliding firstly with Avalonia in the latest Ordovician and then Laurentia to form Laurussia in the middle to late Silur ian. Key faunas, particularly from the Baltic craton, chart this early isol ation and subsequent changes. The Lower Palaeozoic margins of Baltica vary; much of the western margin was subducted during the Caledonian orogeny, th e northern margin is poorly known and much of the eastern margin is preserv ed but heavily tectonised in the Urals. The south and south-eastern margins are the best preserved, despite Caledonian, Hercynian and later tectonism; with craton-margin sequences developed in the central Baltic to Denmark, n orthern Germany and Poland.