Acadian Orogeny
The Acadian orogeny occurred in the Lower Devonian period (Paleozoic era), about 500 Ma. The continents of Laurentia and Baltica collided. The Iapetus Ocean disappeared under this continental collision. These plate tectonic forces built up a mountain range extending from what is now termed the Adirondacks north through Nova Scotia, the British Isles, Norway and the eastern margin of Greenland. Greenland and Scandinavia were situated at the amid the equator and mid tropics (20 to 20 degrees north). The area now comprising Greenland-Scandinavia-British Isles began drifting northward in the Late Carboniferous-Early Permian period. A high amount of volatile magmatism caused dikes parallel to the Tornquist Margin which were formative areas of the North Sea - British Isles -Germany - southwest Sweden area.
Read more about this topic: Geology Of The North Sea