CALEDONIAN OROGENIC BELT

range of mountains situated in northwestern Europe, developed as a result of the opening, closure, and destruction of the Iapetus Ocean in the period from the start of the Cambrian (540 million years ago) to the end of the Silurian (about 408 million years ago). The final collision was between a northwestern European and a North AmericanGreenland continent, and it gave rise to a prominent mountain range the remnants of which now extend in a southwest-northeast direction (present coordinates) from Ireland, Wales, northern England, through eastern Greenland and Norway, to Spitsbergen. The main suture zone, which passes across central Ireland and along the England-Scotland border, separates the two continental blocks that have different sedimentary, igneous, and metamorphic rocks, fossils, and mineralization and different stages of evolution. Uplift, erosion, and extensional collapse of the thickened crust of the mountain range led to the exposure of deep crustal rocks and to deposition of sandstones and conglomerates in basins in the Devonian Period (408 to 360 million years ago).