Caledonian orogeny

The Caledonian orogeny is the second phase of mountain building ( orogeny ) within the Acadischen Gebirgsbildungsära. She began in the Ordovician and reached its peak during the Silurian. " Caledonian " comes from the Latin and Celtic name Caledonia for Scotland.

In the broader sense - - In this Paleozoic orogeny today's hull Mountains of the British Isles, Scandinavia and created the Appalachian Mountains in eastern North America. The east coast of Greenland, Bear Island, the Orkney and Shetland Islands and West Spitsbergen are Caledonian origin.

During the Ordovician - about 450 mya - the earth's continents Laurentia, Baltica and Avalonia were drifted from high southern latitudes towards the equator. They collided in several phases with each other. The Tornquist Ocean between Baltica and Avalonia and the Iapetus Ocean were closed here. The formed during the subduction and closure of the Iapetus Ocean - island arcs and mountain today as the Caledonian mountains, mountain building associated or underlying Caledonian orogeny as.

Development

The exact sequence of these collisions in the period is not known in detail. As is probably true, the following sequence:

• In the Supreme Ordovician Avalonia collided with Baltica first. Probably formed Avalonia a volcanic island arc before it collided with Baltica.
• Off the east coast Laurentias an island arc formed from among the Iapetus was subducted.
• In the Silurian Iapetus was completely closed. It emerged in several phases, the Irish- Scottish Caledonides and the Scandinavian Caledonides. The island arc off the east coast Laurentias was folded into the Appalachians. This branch also continues on the east coast of Greenland to Spitzbergen and Bear Island. In North America, the Appalachians formed. A new super continent - Laurussia or Old Red continent - was born.