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Encyclopedia > Caledonian orogeny

The Caledonian orogeny is a hypothetical series of events in geologic history explaining a group of highland formations that are very similar in composition, stratigraphy and fossils: the mountains and hills of northern England, Wales, Scotland, Ireland and west Norway. In this theory, those ranges were thrust up together primarily in the Silurian Period of the Palaeozoic Era, roughly 444-416 MYBP in the Geologic Time Scale. This orogeny has been given the adjectival form of the ancient name of the Scottish highlands, Caledonia. The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 439 million years ago (mega years ago, mya), to the beginning of the Devonian period, about 408. ... The Palaeozoic is a major division of the geologic timescale, one of four geologic eras. ... The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... Caledonia is primarily a Roman Latin name for a region corresponding approximately to that part of Scotland which is north of a line between the mouths of the Forth and the Clyde. ...

Prior to the acceptance of the theory of Continental Drift and the subsequent science of Plate tectonics, the reasons for the orogeny and its timing remained obscure. Continental drift was verified as a result of data collected in the IGY of 1957/1958. Since then scientists have developed a more precise conceptual structure of geologic time, into which the Caledonian Orogeny fits as follows. Portrayal of shifting continents The concept of continental drift was first proposed by Alfred Wagner. ... Plate tectonics (from the Greek word for one who constructs, τεκτων, tekton) is a theory of geology developed to explain the phenomenon of continental drift, and is currently the theory accepted by the vast majority of scientists working in this area. ... The International Geophysical Year or IGY was an international scientific effort that lasted from July 1, 1957, to December 31, 1958. ...

The Mesozoic Era is marked by the existence of a supercontinent, Pangaea, in which most of the land mass was conjoined into a single large continent surrounded by a single large ocean, Panthalassa. The Caledonian range already existed and was contiguous to the ancestor of the Appalachian Mountains of the eastern United States. The Mesozoic is one of three geologic eras of Phanerozoic eon. ... Map of Pangaea Pangaea (Greek for all lands) is the supercontinent that existed during the Mesozoic era, before the process of plate tectonics separated the component continents. ... Panthalassa (Greek for all seas) was the vast ocean that surrounded the supercontinent Pangaea during the late Paleozoic era and the early Mesozoic era. ... The Appalachian Mountains are a system of North American mountains running from Newfoundland and Labrador, Canada to Alabama in the United States, although the northernmost mainland portion ends at the Gaspé Peninsula of Quebec. ...

The origin of the Caledonian range occurred earlier, during the assembly of Pangaea by the convergence of more ancient plates. In the preceding Ordovician Period, ca. 488-444 MYBP, the largest continent, Gondwana, containing the plates of the future Africa, South America, and Antarctica, was located between the South Pole and the Equator. A second land mass, Laurentia, containing the future northeast section of North America, straddled the equator. To the northeast was the Siberian Plate, separated from Gondwana by the Palaeotethys Ocean; to the southeast, the Baltic Plate, or Baltica, separated from Gondwana by Iapetus Ocean. In the Iapetus Ocean was a long archipelago, Avalonia, containing New England, Nova Scotia and the British Isles. It was divided from Gondwana by an oceanic rift. The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... Pangea broke into the two supercontinents, Laurasia and Gondwana The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America, Africa, Madagascar, India, Arabia, Australia-New Guinea and New Zealand. ... Africa is the worlds second-largest continent and 3rd most populous. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... Location of the South Pole in the Antarctic continent. ... The equator is an imaginary line drawn around a planet, halfway between the poles. ... Laurentia is the craton at the heart of North America. ... World map showing location of North America A satellite composite image of North America North America is a continent in the northern hemisphere, bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west... Baltica is the craton beneath northwestern Eurasia. ... The Iapetus Ocean was an Ocean that existed in the Southern Hemisphere between Scotland, England and Scandinavia between 400 and 600 million years ago. ... An archipelago is a landform which consists of a chain or cluster of islands. ... Avalonia was a paleomicrocontinent also known as a Terrane. ... While the states marked in red show the core of New England, the regions cultural influence may cover a greater or lesser area than shown. ... Motto: Munit Haec et Altera Vincit (One defends and the other conquers) Other Canadian provinces and territories Capital Halifax Largest city Halifax Lieutenant Governor Myra A. Freeman Premier John Hamm (PC) Area 55,283 km² (12th)  - Land 53,338 km²  - Water 1,946 km² (3. ... The British Isles consist of Great Britain, Ireland and a number of much smaller surrounding islands. ... In geology, a rift is a place where the Earths lithosphere is expanding. ...

In the Ordovician Period, the rift began to open, pushing Baltica and Avalonia in the direction of Laurentia by sea-floor spreading. Baltica and northern Avalonia collided first, causing the Caledonian Origeny of the Silurian. At the end of the Silurian and in the subsequent Devonian, the rest of Avalonia collided, causing the Acadian Orogeny of North America, which raised the Appalachian Mountains. The Devonian is a major division of the geologic timescale that extends from the end of the Silurian period (360 million years ago (mya)) to the beginning of the Mississippian subperiod of the Carboniferous (408. ... The Acadian orogeny is a middle Paleozoic deformation, especially in the northern Appalachians, between Alabama and Newfoundland. ... The Appalachian Mountains are a system of North American mountains running from Newfoundland and Labrador, Canada to Alabama in the United States, although the northernmost mainland portion ends at the Gaspé Peninsula of Quebec. ...

External Links

  Results from FactBites:
Caledonian Orogeny redefined, The Journal of the Geological Society - Find Articles (901 words)
The Caledonian Orogeny is here redefined to include all the Cambrian, Ordovician, Silurian and Devonian tectonic events associated with the development and closure of those parts of the Iapetus Ocean, which were situated between Laurentia (to the NW) and Baltica and Avalonia (to the SE and east).
We suggest that the term `Caledonian Orogeny' be restricted in this geographic sense, but that (as in modern usage) it continues to encompass a series of tectonic, or orogenic, phases (related to arc-arc, arc-continent and continent-continent collisions as Iapetus was closing).
The term 'Caledonian' is derived from the Latin word for Scotland and was commonly employed in British nineteenth century literature to refer to the Scottish Highlands.
Caledonian Orogeny (141 words)
During the Lower Palaeozoic the continents of Baltica, Avalonia and Laurentia were separated by the Iapetus Ocean.
The Caledonian Orogeny marks the closure of the Iapetus Ocean.
The Caledonide mountain belt associated with this orogeny stretched from present day Scandinavia, across the British Isles, to the east coast of America.
  More results at FactBites »



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