Caledonian System is a mountain system formed during the Caledonian orogeny, caused by the collision of the continents Laurentia, Baltica, and Avalonia in the Paleozoic era (Cambrian and Devonian, 520-400 Ma). The mountain ranges formed by the Caledonian orogeny lie on both sides of the Atlantic Ocean, which formed later and separated them into two parts. In Europe, this includes the mountains of the British Isles (excluding England and southern Ireland), the Scandinavian Mountains, and Svalbard. Most of these ancient European mountains gained height during later orogenies, but their material surfaced during the Caledonian period. The highest peak is the Norwegian Galdhøpiggen (2469 m).