acadian orogeny africa antarctica armorica armorican massif atlantic ocean australia austria avalonia back-arc basin baltica british isles caledonia cambrian carboniferous continental collision continental crust denmark devonian ediacaran eduard suess england epoch era euramerica eurasia france geological society of america geological society of london geological history germany gondwana greenland hans stille iapetus ocean ireland latin laurentia metamorphism new brunswick new england newfoundland north america north sea nova scotia ordovician orogeny paleozoic pangaea poland portugal rheic ocean rhenohercynian basin royal dutch shell scandinavia scotland siberia silurian south america subduction supercontinent svalbard taconic orogeny tectonics terrane wales