Caledonian Orogeny

The closure of the Iapetus Ocean drove the collision of Laurentia, Baltica, and the Avalonia microcontinent across roughly 100 million years. This mountain-building event occurred in distinct phases: the Grampian Event (480-460 Ma), the Scandian Event (440 Ma), and the docking of Avalonia (425 Ma). The resulting Caledonian Mountains left metamorphic rocks, thrust belts, and granite intrusions across Scotland, Scandinavia, and Greenland.