Caledonian orogeny

The Caledonian orogeny was a mountain building era. It left its mark in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland, northern Europe and the eastern United States.
The events occurred from the Ordovician to early Devonian, roughly 490390 million years ago (mya). It was caused by the closure of the Iapetus Ocean when the continents and lands of Laurentia, Baltica and Avalonia collided.
The Caledonian orogeny is named after Caledonia, the Latin name for Scotland. The name is not used for an absolute period of time: it applies only to the series of mountain-building events.
Part of the mountain chain ended up in modern North America, where it is called the Acadian orogeny (see Appalachian Mountains).
Stages.
The Caledonian orogeny was one of several orogenies that would eventually form the supercontinent Pangaea later in the Palaeozoic era. The main phase of the Caledonian orogeny happened from about 425 to 395 million years ago.
Continental collision started in the mid Silurian, and mountain building took place in the early Devonian (from 407 million years ago onward).