Scandinavian CaledonidesMountain belts are a source of all sorts of exciting and significant fossil

Scandinavian CaledonidesMountain belts are a source of all sorts of exciting and significant fossil assemblages. The Scandinavian Caledonides are no exception. This mountain belt stretches for some 1118 miles (1800km) from north to southwest Norway, never exceeding a width of 300km.It developed during a so-called Wilson cycle (the opening, closing and subsequent destruction of an ancient ocean, named after J. Tuzo Wilson) culminating in the collision of the Baltic plate with those of Avalonia (England, Wales and parts of eastern North America and north central Europe) and then Laurentia (cratonic North America).During its transit from high to low latitudes in the Early Paleozoic, Baltica rotated anti-clockwise and first captured terranes adjacent to the craton itself with Baltic faunas, followed by island terranes from within the Iapetus Ocean, with endemic taxa (unique species defined to a geographic zone), and finally island complexes that were marginal to the Laurentian plate with North American faunas.The mountain belt in its pile of thrust sheets stores much of the biogeographic history of the Iapetus Ocean and its marginal terranes. Moreover during the Late Silurian-Devonian, as the mountain belt continued to rise, marginal basins contained remarkable marine marginal biotas with spectacular eurypterid faunas (Eurypterids are an extinct group of arthropods that are related to arachnids and include the largest known arthropods to have ever lived). Adjacent basins, for example in Scotland, contain some of the earliest land arthropods and plants.So the collision of plates and the generation of a huge mountain belt was not entirely a destructive process. It has helped preserve key evidence for an ancient ocean with diverse and endemic faunas that helped contribute to the great Ordovician biodiversification event while its later non-marine basins hold critical information on the early development of life on land.~ JMImage Credit: Scandinavian Mountains: Labelled for re-use. http://bit.ly/1H03TYKCaledonian orogeny: Labelled for re-use. http://bit.ly/1UotlAcMore Info:Harper, D.A.T. 2001. Fossils in mountain belts. Geology Today 17, 148-52.Roberts, D. (2003). The Scandinavian Caledonides: event chronology, palaeogeographic settings and likely modern analogues. Tectonophysics, 365(1), 283-299. http://bit.ly/1LQDyD2Rey, P., Burg, J. P., & Casey, M. (1997). The Scandinavian Caledonides and their relationship to the Variscan belt. Geological Society, London, Special Publications, 121(1), 179-200. http://bit.ly/1CdOPtL -- source link

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