The Caledonian orogeny was a mountain-building era recorded in the northern parts of Ireland and Britain, the Scandinavian Mountains, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian 490–390 million years ago, it was caused by the closure of the Iapetus Ocean when the continents and terranes of Laurentia and Avalonia collided. The Caledonian orogeny is named for the Latin name for Scotland; the name was first used in 1885 by Austrian geologist Eduard Suess for an episode of mountain building in northern Europe that predated the Devonian period. Geologists like Émile Haug and Hans Stille saw the Caledonian orogeny as one of several episodic phases of mountain building that had occurred during Earth's history. Current understanding has it that the Caledonian orogeny encompasses a number of tectonic phases that can laterally be diachronous; the name "Caledonian" can therefore not be used for an absolute period of geological time, it applies only to a series of tectonically related events.
The Caledonian orogeny was one of several orogenies that would form the supercontinent Pangaea in the Late Paleozoic era. In the Early Paleozoic the majority of all continental landmasses were united in the paleocontinent of Gondwana, containing the crust of future Africa, South America, southern Eurasia and Antarctica, which lay centered on the South Pole. Between 650 and 550 million years ago the smaller continents of Laurentia and Siberia had separated from Gondwana to move northward towards the equator. In the process, the Iapetus Ocean between Gondwana and Laurentia closed. In the Early Ordovician period the microcontinent Avalonia began to separate from the northern margin of Gondwana; some early phases of deformation and/or metamorphism are recognized in the Scandinavian Caledonides. The first phase, included in the Caledonian orogeny is the Finnmarkian phase at 505 million years ago. Another phase was the Jämtlandian phase at 455 million years ago; these phases are explained by the assumption that the western edge of Baltica collided with an island arc or microcontinent.
In a similar way, the eastern edge of Laurentia collided with an island arc during the Taconic orogeny. During the Ordovician, the small continent of Avalonia moved independently in a northeastern direction towards Baltica; this motion was accommodated by the subduction of the southeastern Iapetus Ocean beneath eastern Avalonia. In the Late Ordovician continental collision started between Baltica; the Tornquist Sea disappeared in the process, the remaining suture is the Tornquist line, which runs under the North Sea, southern Denmark and northern Germany and Poland. The main phase of the Caledonian orogeny is called the Scandian phase in Scandinavia and the Grampian phase in Britain, it was caused by the collision between Baltica. The Iapetus Ocean first closed in the north in the south. Therefore, the collision between Baltica and Laurentia took place a little earlier than that between Avalonia and Laurentia. Continental collision started in the Mid Silurian and mountain building took place in the Early Devonian.
In North America, the collision between Avalonia and Laurentia is called the Acadian orogeny. According to some authors, the Caledonian continental collisions involved another microcontinent, Armorica smaller than Avalonia; this microcontinent did not form one consistent unit, but was instead a series of fragments, of which the current Armorican and Bohemian Massifs are the most important. The ocean between the combined continental mass of Laurentia and Avalonia and Armorica is called the Rheic Ocean; the paleogeographic position of the Armorica crustal fragments between the Ordovician and Carboniferous is disputed though. There are indications that the Bohemian Massif started moving northward from the Ordovician onward, but many authors place the accretion of the Armorican terranes with the southern margin of Laurussia in the Carboniferous Hercynian orogeny; the Rhenohercynian basin, a back-arc basin, formed at the southern margin of Euramerica just after the Caledonian orogeny. According to these authors, a small rim from Euramerica rifted off.
The basin closed when these Caledonian deformed terranes were accreted again to Laurussia during the Hercynian orogeny. Scandinavian Mountains Świętokrzyskie Mountains Geological structure of Great Britain Central Pangean Mountains Iapetus Suture Queen Louise Land Trans-European Suture Zone Cocks, L. R. M. & Torsvik, T. H.. G. & Stephenson, R. A.: European Lithosphere Dynamics, Geological Society of London Memoirs 32, pp. 83–95. Cocks, L. R. M.. S. & Staal, C. R. van. Fossen, H. & Dunlap, J. W..
Holocene climatic optimum
The Holocene Climate Optimum was a warm period during the interval 9,000 to 5,000 years BP, with a thermal maximum around 8000 years BP. It has been known by many other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum and Mid-Holocene Warm Period; this warm period was followed by a gradual decline until about two millennia ago. For other temperature fluctuations, see temperature record. For other past climate fluctuation, see paleoclimatology. For the pollen zone and Blytt-Sernander period, associated with the climate optimum, see Atlantic; the Holocene Climate Optimum warm event consisted of increases of up to 4 °C near the North Pole. Northwestern Europe experienced warming; the average temperature change appears to have declined with latitude and so no change in mean temperature is reported at low and middle latitudes. Tropical reefs tend to show temperature increases of less than 1 °C. In terms of the global average, temperatures were warmer than now.
While temperatures in the Northern Hemisphere were warmer than average during the summers, the Tropics and parts of the Southern Hemisphere were colder than average. Out of 140 sites across the western Arctic, there is clear evidence for conditions warmer than now at 120 sites. At 16 sites, where quantitative estimates have been obtained, local HTM temperatures were on average 1.6±0.8 °C higher than now. Northwestern North America had peak warmth first, from 11,000 to 9,000 years ago, the Laurentide ice sheet still chilled the continent. Northeastern North America experienced peak warming 4,000 years later. Along the Arctic Coastal Plain in Alaska, there are indications of summer temperatures 2–3 °C warmer than present. Research indicates. Current desert regions of Central Asia were extensively forested due to higher rainfall, the warm temperate forest belts in China and Japan were extended northwards. West African sediments additionally record the African Humid Period, an interval, between 16,000 and 6,000 years ago, when Africa was much wetter.
This was caused by a strengthening of the African monsoon by changes in summer radiation, resulting from long-term variations in the Earth's orbit around the Sun. The "Green Sahara" was dotted with numerous lakes, containing typical African lake crocodile and hippopotamus fauna. A curious discovery from the marine sediments is that the transitions into and out of the wet period occurred within decades, not the previously-thought extended periods, it is hypothesized that humans played a role in altering the vegetation structure of North Africa at some point after 8,000 years ago, when they introduced domesticated animals. This introduction contributed to the rapid transition to the arid conditions found in many locations in the Sahara. In the far Southern Hemisphere, the warmest period during the Holocene appears to have been 8,000 to 10,500 years ago following the end of the last ice age. By 6,000 years ago, the time associated with the Holocene Climatic Optimum in the Northern Hemisphere, they had reached temperatures similar to present ones, they did not participate in the temperature changes of the north.
However, some authors have used the term "Holocene Climatic Optimum" to describe the earlier southern warm period, as well. A comparison of the delta profiles at Byrd Station, West Antarctica and Camp Century, Northwest Greenland, shows the post glacial climatic optimum. Points of correlation indicate that in these two locations the Holocene climatic optimum occurred at the same time. A similar comparison is evident between the Dye 3 1979 and Camp Century 1963 cores regarding this period; the Hans Tausen Iskappe in Peary Land was drilled in 1977 with a new deep drill to 325 m. The ice core contained distinct melt layers all the way to bedrock indicating that Hans Tausen Iskappe contains no ice from the last glaciation. From the delta-profile, the Renland ice cap in the Scoresby Sound has always been separated from the inland ice, yet all the delta-leaps revealed in the Camp Century 1963 core recurred in the Renland 1985 ice core; the Renland ice core from East Greenland covers a full glacial cycle from the Holocene into the previous Eemian interglacial.
The Renland ice core is 325 m long. Although the depths are different, the GRIP and NGRIP cores contain this climatic optimum at similar times; the climatic event was a result of predictable changes in the Earth's orbit and a continuation of changes that caused the end of the last glacial period. The effect would have had maximum Northern Hemisphere heating 9,000 years ago, when the axial tilt was 24° and the nearest approach to the Sun was during the Northern Hemisphere's summer; the calculated Milankovitch Forcing would have provided 0.2% more solar radiation to the Northern Hemisphere in summer, tending to cause greater heating. There seems to have been the predicted southward shift in the global band of thunderstorms, the Intertropical Convergence Zone. However, orbital forcing would pre
The Paleozoic Era is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, is subdivided into six geologic periods: the Cambrian, Silurian, Devonian and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era; the Paleozoic was a time of dramatic geological and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, fish, amphibians and diapsids all evolved during the Paleozoic. Life began in the ocean but transitioned onto land, by the late Paleozoic, it was dominated by various forms of organisms. Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, sophisticated diapsids and synapsids were dominant and the first modern plants appeared.
The Paleozoic Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover. Recovery of life in the sea may have been much faster; the Paleozoic era began and ended with supercontinents and in between were the rise of mountains along the continental margins, flooding and draining of shallow seas between the mountain ranges, in the interior of the continents. At its start, the supercontinent Pannotia broke up. Paleoclimatic studies and evidence of glaciers indicate that central Africa was most in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwana was forming. By mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, a subduction plate uplifted eastern Australia. By the late Paleozoic, continental collisions formed the supercontinent of Pangaea and resulted in some of the great mountain chains, including the Appalachians, Ural Mountains, mountains of Tasmania.
There are six periods in the Paleozoic Era: Cambrian, Silurian, Devonian and the Permian. The Cambrian spans from 541 million years to 485 million years and is the first period of the Paleozoic era of the Phanerozoic; the Cambrian marked a boom in evolution in an event known as the Cambrian explosion in which the largest number of creatures evolved in any single period of the history of the Earth. Creatures like algae evolved, but the most ubiquitous of that period were the armored arthropods, like trilobites. All marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, most of which became the supercontinent Gondwana; the Ordovician spanned from 485 million years to 443 million years ago. The Ordovician was a time in Earth's history in which many of the biological classes still prevalent today evolved, such as primitive fish and coral; the most common forms of life, were trilobites and shellfish. More the first arthropods went ashore to colonize the empty continent of Gondwana.
By the end of the Ordovician, Gondwana was at the south pole, early North America had collided with Europe, closing the Atlantic Ocean. Glaciation of Africa resulted in a major drop in sea level, killing off all life that had established along coastal Gondwana. Glaciation may have caused the Ordovician–Silurian extinction events, in which 60% of marine invertebrates and 25% of families became extinct, is considered the first mass extinction event and the second deadliest; the Silurian spanned from 443 to 416 million years ago. The Silurian saw the rejuvenation of life; this period saw the mass evolution of fish, as jawless fish became more numerous, jawed fish evolved, the first freshwater fish evolved, though arthropods, such as sea scorpions, were still apex predators. Terrestrial life evolved, including early arachnids and centipedes; the evolution of vascular plants allowed plants to gain a foothold on land. These early plants were the forerunners of all plant life on land. During this time, there were four continents: Gondwana, Laurentia and Avalonia.
The recent rise in sea levels allowed many new species to thrive in water. The Devonian spanned from 416 million years to 359 million years ago. Known as "The Age of the Fish", the Devonian featured a huge diversification of fish, including armored fish like Dunkleosteus and lobe-finned fish which evolved into the first tetrapods. On land, plant groups diversified in an event known as the Devonian Explosion when plants made lignin allowing taller growth and vascular tissue: the first trees evolved, as well as seeds; this event diversified arthropod life, by providing them new habitats. The first amphibians evolved, the fish were now at the top of the food chain. Near the end of the Devonian, 70% of all species became extinct in an event known as the Late Devonian extinction, the Earth's second mass extinction event; the Carboniferous spanned from 359 million to 299 million years ago. During this time, average global temperatures were exc
Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
The Hardangervidda Natursenter is a museum and visitor center of the Hardangervidda National Park in Norway. This centre is located in the village of Øvre Eidfjord in the municipality of Eidfjord in Hordaland county. Official site Eidfjord Hardangervidda Natursente Eidfjord Hardangervidda Natursente Tinn
A national park is a park in use for conservation purposes. It is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently, there is a common idea: the conservation of'wild nature' for posterity and as a symbol of national pride. An international organization, the International Union for Conservation of Nature, its World Commission on Protected Areas, has defined "National Park" as its Category II type of protected areas. While this type of national park had been proposed the United States established the first "public park or pleasuring-ground for the benefit and enjoyment of the people", Yellowstone National Park, in 1872. Although Yellowstone was not termed a "national park" in its establishing law, it was always termed such in practice and is held to be the first and oldest national park in the world. However, the Tobago Main Ridge Forest Reserve, the area surrounding Bogd Khan Uul Mountain are seen as the oldest protected areas, predating Yellowstone by nearly a century.
The first area to use "national park" in its creation legislation was the U. S.'s Mackinac, in 1875. Australia's Royal National Park, established in 1879, was the world's third official national park. In 1895 ownership of Mackinac National Park was transferred to the State of Michigan as a state park and national park status was lost; as a result, Australia's Royal National Park is by some considerations the second oldest national park now in existence. Canada established Parks Canada in 1911, becoming the world's first national service dedicated to protecting and presenting natural and historical treasures; the largest national park in the world meeting the IUCN definition is the Northeast Greenland National Park, established in 1974. According to the IUCN, 6,555 national parks worldwide met its criteria in 2006. IUCN is still discussing the parameters of defining a national park. National parks are always open to visitors. Most national parks provide outdoor recreation and camping opportunities as well as classes designed to educate the public on the importance of conservation and the natural wonders of the land in which the national park is located.
In 1969, the IUCN declared a national park to be a large area with the following defining characteristics: One or several ecosystems not materially altered by human exploitation and occupation, where plant and animal species, geomorphological sites and habitats are of special scientific and recreational interest or which contain a natural landscape of great beauty. In 1971, these criteria were further expanded upon leading to more clear and defined benchmarks to evaluate a national park; these include: Minimum size of 1,000 hectares within zones in which protection of nature takes precedence Statutory legal protection Budget and staff sufficient to provide sufficient effective protection Prohibition of exploitation of natural resources qualified by such activities as sport, fishing, the need for management, etc. While the term national park is now defined by the IUCN, many protected areas in many countries are called national park when they correspond to other categories of the IUCN Protected Area Management Definition, for example: Swiss National Park, Switzerland: IUCN Ia - Strict Nature Reserve Everglades National Park, United States: IUCN Ib - Wilderness Area Victoria Falls National Park, Zimbabwe: IUCN III - National Monument Vitosha National Park, Bulgaria: IUCN IV - Habitat Management Area New Forest National Park, United Kingdom: IUCN V - Protected Landscape Etniko Ygrotopiko Parko Delta Evrou, Greece: IUCN VI - Managed Resource Protected AreaWhile national parks are understood to be administered by national governments, in Australia national parks are run by state governments and predate the Federation of Australia.
In Canada, there are both national parks operated by the federal government and provincial or territorial parks operated by the provincial and territorial governments, although nearly all are still national parks by the IUCN definition. In many countries, including Indonesia, the Netherlands, the United Kingdom, national parks do not adhere to the IUCN definition, while some areas which adhere to the IUCN definition are not designated as national parks. In 1810, the English poet William Wordsworth described the Lake District as a sort of national property, in which every man has a right and interest who has an eye to perceive and a heart to enjoy; the painter George Catlin, in his travels through the American West, wrote during the 1830s that the Native Americans in the United States might be preserved...in a magnificent park... A nation's Park, containing man and beast, in all the wild and freshness of their nature's beauty! The first effort by the U. S. Federal government to set aside such protected lands was on 20 April 1832, when President Andrew Jackson signed legislation that the 22nd United States Congress had enacted to set aside four sections of land around what is now Hot Springs, Arkansas, to protect the natural, thermal springs and adjoining mountainsides for the futur