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162-534: Pangaea or Pangea ( / p æ n ˈ dʒ iː ə / pan- JEE -ə ) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana , Euramerica and Siberia during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of

324-538: A preservation bias . During the late Ordovician (~458.4 Ma), the particular configuration of Gondwana may have allowed for glaciation and high CO 2 levels to occur at the same time. However, some geologists disagree and think that there was a temperature increase at this time. This increase may have been strongly influenced by the movement of Gondwana across the South Pole, which may have prevented lengthy snow accumulation. Although late Ordovician temperatures at

486-472: A fragile ecosystem known as the Southern Appalachian spruce–fir forest . Fraser fir rarely occurs below 5,500 ft (1,700 m), and becomes the dominant tree type at 6,200 ft (1,900 m). By contrast, balsam fir is found from near sea level to the tree line in the northern Appalachians, but ranges only as far south as Virginia and West Virginia in the central Appalachians, where it

648-735: A great thickness of sediment accumulated. Eventually, the tectonic forces pulling the two continents apart became so strong that an ocean formed off the eastern coast of the Laurentian margin. This was called the Iapetus Ocean and was the precursor of the modern Atlantic Ocean. The rocks of the Valley and Ridge province formed over millions of years, in the Iapetus. Shells and other hard parts of ancient marine plants and animals accumulated to form limey deposits that later became limestone. This

810-550: A low number of passive margins during 336 to 275 Ma, and its break-up is indicated accurately by an increase in passive margins. Orogenic belts can form during the assembly of continents and supercontinents. The orogenic belts present on continental blocks are classified into three different categories and have implications for interpreting geologic bodies. Intercratonic orogenic belts are characteristic of ocean basin closure. Clear indicators of intracratonic activity contain ophiolites and other oceanic materials that are present in

972-502: A name for the tribe and region spreading well inland to the north. Pánfilo de Narváez 's expedition first entered Apalachee territory on June 15, 1528, and applied the name. Now spelled "Appalachian", it is the fourth-oldest surviving European place-name in the US. After the 1540 expedition of Hernando de Soto , Spanish cartographers began to apply the name of the tribe to the mountains themselves. The first cartographic appearance of Apalchen

1134-672: A new ocean opened up, the Rheic Ocean , during the Middle to Late Devonian, and subsequently its closure would result in the formation of the Alleghanian orogeny . As the continental plates moved closer together, fragments of oceanic crust, islands, and other continental masses collided with the eastern margin of ancestral North America. By this time, plants had appeared on land, followed by scorpions, insects, and amphibians. The ocean continued to shrink until, about 270 million years ago,

1296-407: A northward direction, separating it from Antarctica and allowing complete oceanic circulation around Antarctica for the first time. This motion, together with decreasing atmospheric carbon dioxide concentrations, caused a rapid cooling of Antarctica and allowed glaciers to form. This glaciation eventually coalesced into the kilometers-thick ice sheets seen today. Other major events took place during

1458-504: A number of deciduous rhododendrons (azaleas), and smaller heaths such as teaberry ( Gaultheria procumbens ) and trailing arbutus ( Epigaea repens ). The evergreen great rhododendron ( Rhododendron maximum ) is characteristic of moist stream valleys. These occurrences are in line with the prevailing acidic character of most oak forest soils. In contrast, the much rarer chinquapin oak ( Quercus muehlenbergii ) demands alkaline soils and generally grows where limestone rock

1620-444: A number of serious insect and disease outbreaks. Among the most conspicuous is that of the introduced spongy moth ( Lymantria dispar ), which infests primarily oaks, causing severe defoliation and tree mortality. But it also has the benefit of eliminating weak individuals, and thus improving the genetic stock, as well as creating rich habitat of a type through accumulation of dead wood. Because hardwoods sprout so readily, this moth

1782-578: A single lava flow is also undetermined. These are important factors on how flood basalts influenced paleoclimate . Global palaeogeography and plate interactions as far back as Pangaea are relatively well understood today. However, the evidence becomes more sparse further back in geologic history. Marine magnetic anomalies, passive margin match-ups, geologic interpretation of orogenic belts , paleomagnetism, paleobiogeography of fossils, and distribution of climatically sensitive strata are all methods to obtain evidence for continent locality and indicators of

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1944-401: A slab of the subducted crust is denser than the surrounding mantle, it sinks to discontinuity. Once the slabs build up, they will sink through to the lower mantle in what is known as a "slab avalanche". This displacement at the discontinuity will cause the lower mantle to compensate and rise elsewhere. The rising mantle can form a plume or superplume. Besides having compositional effects on

2106-529: A supercontinent would have to show intracratonic orogenic belts. However, interpretation of orogenic belts can be difficult. The collision of Gondwana and Laurasia occurred in the late Palaeozoic. By this collision, the Variscan mountain range was created, along the equator. This 6000-km-long mountain range is usually referred to in two parts: the Hercynian mountain range of the late Carboniferous makes up

2268-544: A variety of oaks ( Quercus spp.), hickories ( Carya spp.) and, in the past, by the American chestnut ( Castanea dentata ). The American chestnut was virtually eliminated as a canopy species by the introduced fungal chestnut blight ( Cryphonectaria parasitica ), but lives on as sapling-sized sprouts that originate from roots, which are not killed by the fungus. In present-day forest canopies, chestnut has been largely replaced by oaks. The oak forests of

2430-483: Is a boreal species that forms a few high elevation outliers as far south as West Virginia. All of these species except white pine tend to occupy sandy, rocky, poor soil sites, which are mostly acidic in character. White pine, a large species valued for its timber, tends to do best in rich, moist soil, either acidic or alkaline in character. Pitch pine is also at home in acidic, boggy soil, and Table Mountain pine may occasionally be found in this habitat as well. Shortleaf pine

2592-569: Is an association between the rifting and breakup of continents and supercontinents and glacial epochs. According to the model for Precambrian supercontinent series, the breakup of Kenorland and Rodinia was associated with the Paleoproterozoic and Neoproterozoic glacial epochs, respectively. In contrast, the Protopangea–Paleopangea theory shows that these glaciations correlated with periods of low continental velocity, and it

2754-503: Is based on both palaeomagnetic and geological evidence and proposes that the continental crust comprised a single supercontinent from ~2.72 Ga until break-up during the Ediacaran period after ~0.573 Ga . The reconstruction is derived from the observation that palaeomagnetic poles converge to quasi-static positions for long intervals between ~2.72–2.115 Ga; 1.35–1.13 Ga; and 0.75–0.573 Ga with only small peripheral modifications to

2916-448: Is concluded that a fall in tectonic and corresponding volcanic activity was responsible for these intervals of global frigidity. During the accumulation of supercontinents with times of regional uplift, glacial epochs seem to be rare with little supporting evidence. However, the lack of evidence does not allow for the conclusion that glacial epochs are not associated with the collisional assembly of supercontinents. This could just represent

3078-652: Is currently on a collision course with eastern Asia . Both Australia and India are currently moving northeast at 5–6 centimeters (2–3 in) per year. Antarctica has been near or at the South Pole since the formation of Pangaea about 280 Ma. India started to collide with Asia beginning about 35 Ma, forming the Himalayan orogeny and closing the Tethys Ocean; this collision continues today. The African Plate started to change directions, from west to northwest toward Europe, and South America began to move in

3240-546: Is evidence for a large orographic barrier within the interior of Pangaea during the late Paleozoic (~251.9 Ma). The possibility of the southwest–northeast trending Appalachian-Hercynian Mountains makes the region's monsoonal circulations potentially relatable to present-day monsoonal circulations surrounding the Tibetan Plateau, which is known to positively influence the magnitude of monsoonal periods within Eurasia. It

3402-403: Is found at high elevations in the northern Appalachians, and in bogs as far south as Pennsylvania. The Appalachians are also home to two species of fir, the boreal balsam fir ( Abies balsamea ), and the southern high elevation endemic, Fraser fir ( Abies fraseri ). Fraser fir is endemic to the highest parts of the southern Appalachian Mountains, where along with red spruce it forms

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3564-479: Is found in the geology of adjacent continents, including matching geological trends between the eastern coast of South America and the western coast of Africa . The polar ice cap of the Carboniferous covered the southern end of Pangaea. Glacial deposits, specifically till , of the same age and structure are found on many separate continents that would have been together in the continent of Pangaea. The continuity of mountain chains provides further evidence, such as

3726-533: Is generally found in warmer habitats and at lower elevations than the other species. All the species listed do best in open or lightly shaded habitats, although white pine also thrives in shady coves, valleys, and on floodplains. The Appalachians are characterized by a wealth of large, beautiful deciduous broadleaf (hardwood) trees. Their occurrences are best summarized and described in E. Lucy Braun 's 1950 classic, Deciduous Forests of Eastern North America (Macmillan, New York). The most diverse and richest forests are

3888-533: Is identical for all contemporaneous samples, can be subtracted, leaving the portion that shows continental drift and can be used to help reconstruct earlier continental latitudes and orientations. Pangaea is the most recent supercontinent reconstructed from the geologic record and therefore is by far the best understood. The formation of supercontinents and their breakup appears to be cyclical through Earth's history. There may have been several others before Pangaea. Paleomagnetic measurements help geologists determine

4050-414: Is near the surface. Hence no ericaceous shrubs are associated with it. The Appalachian flora also include a diverse assemblage of bryophytes (mosses and liverworts), as well as fungi . Some species are rare and/or endemic. As with vascular plants , these tend to be closely related to the character of the soils and the thermal environment in which they are found. Eastern deciduous forests are subject to

4212-525: Is not as harmful as the hemlock woolly adelgid . Perhaps more serious is the introduced beech bark disease complex, which includes both a scale insect ( Cryptococcus fagisuga ) and fungal components. During the 19th and early 20th centuries, the Appalachian forests were subject to severe and destructive logging and land clearing, which resulted in the designation of the national forests and parks as well many state-protected areas. However, these and

4374-527: Is now the southern United States, the Ococee Basin was formed. Seawater filled the basin. Rivers from the surrounding countryside carried clay, silt, sand, and gravel to the basin, much as rivers today carry sediment from the midcontinent region to the Gulf of Mexico. The sediment spread out in layers on the basin floor. The basin continued to subside, and over a long period of time, probably millions of years,

4536-532: Is on Diego Gutiérrez 's map of 1562; the first use for the mountain range is the map of Jacques le Moyne de Morgues in 1565. The name was not commonly used for the whole mountain range until the late 19th century. A competing and often more popular name was the "Allegheny Mountains", "Alleghenies", and even "Alleghania". In the early 19th century, Washington Irving proposed renaming the United States either Appalachia or Alleghania. In U.S. dialects in

4698-552: Is possible that the cratons of Kalahari , and Rio Plato , were also part of that early collision since they were present as Rodinia broke up). Mountain-building referred to as the Grenville Orogeny occurred along the boundaries of the cratons. The present Appalachian Mountains have at least two areas which are made from rock formations that were formed during this orogeny - the Blue Ridge Mountains and

4860-477: Is seen today in Eurasia , and rock record shows evidence of continentality in the middle of Pangaea. The term glacial-epoch refers to a long episode of glaciation on Earth over millions of years. Glaciers have major implications on the climate, particularly through sea level change . Changes in the position and elevation of the continents, the paleolatitude and ocean circulation affect the glacial epochs. There

5022-659: Is sometimes termed the Appalachian orogeny , writing communities struggle to agree on an encyclopedic definition of the mountain range. However, each of the governments has an agency that informs the public about the major landforms that make up the countries, the United States Geological Survey (USGS) and the Geological Survey of Canada (GSC). The landforms are referred to as physiographic regions. The regions create precise boundaries from which maps can be drawn. The Appalachian Highlands

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5184-706: Is subject to the hemlock woolly adelgid ( Adelges tsugae ), an introduced insect, that is rapidly extirpating it as a forest tree. Less abundant, and restricted to the southern Appalachians, is Carolina hemlock ( Tsuga caroliniana ). Like Canada hemlock, this tree suffers severely from the hemlock woolly adelgid. Several species of pines characteristic of the Appalachians are eastern white pine ( Pinus strobus ), Virginia pine ( Pinus virginiana ), pitch pine ( Pinus rigida ), Table Mountain pine ( Pinus pungens ) and shortleaf pine ( Pinus echinata ). Red pine ( Pinus resinosa )

5346-477: Is the fifth oxygenation stage. One of the reasons indicating this period to be an oxygenation event is the increase in redox -sensitive molybdenum in black shales . The sixth event occurred between 360 and 260 Ma and was identified by models suggesting shifts in the balance of S in sulfates and C in carbonates , which were strongly influenced by an increase in atmospheric oxygen. Granites and detrital zircons have notably similar and episodic appearances in

5508-460: Is the name of one of the eight physiographic regions of the contiguous 48 United States. The Appalachian Uplands is the name of one of seven physiographic regions of Canada. The second level in the physiographic classification schema for the USGS is "province", the same word as Canada uses to divide its political subdivisions, meaning that the terminology used by the two countries do not match below

5670-439: Is the opening and closing of an individual oceanic basin . The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle. However, supercontinent cycles and Wilson cycles were both involved in the creation of Pangaea and Rodinia. Secular trends such as carbonatites , granulites , eclogites , and greenstone belt deformation events are all possible indicators of Precambrian supercontinent cyclicity, although

5832-506: Is the same process by which limestone forms in modern oceans. The weathering of limestone, now exposed at the land surface, produces the lime-rich soils that are so prevalent in the fertile farmland of the Valley and Ridge province. During this continental break-up, around 600 million to 560 million years ago, volcanic activity was present along the tectonic margins. There is evidence of this activity in today's Blue Ridge Mountains. Mount Rogers , Whitetop Mountain , and Pine Mountain are all

5994-466: Is therefore somewhat expected that lower topography in other regions of the supercontinent during the Jurassic would negatively influence precipitation variations. The breakup of supercontinents may have affected local precipitation. When any supercontinent breaks up, there will be an increase in precipitation runoff over the surface of the continental landmasses, increasing silicate weathering and

6156-504: Is thought that the Earth's oxygen content has risen in stages: six or seven steps that are timed very closely to the development of Earth's supercontinents. The process of Earth's increase in atmospheric oxygen content is theorized to have started with the continent-continent collision of huge landmasses forming supercontinents, and therefore possibly supercontinent mountain ranges (super-mountains). These super-mountains would have eroded, and

6318-474: Is thought to have been approximately 10 degrees Celsius warmer along 90 degrees East paleolongitude compared to the present temperature of today's central Eurasia. Many studies of the Milankovitch cycles during supercontinent time periods have focused on the mid-Cretaceous. Present amplitudes of Milankovitch cycles over present-day Eurasia may be mirrored in both the southern and northern hemispheres of

6480-464: Is usually confined above 3,900 ft (1,200 m) asl, except in cold valleys. Curiously, it is associated with oaks in Virginia. The balsam fir of Virginia and West Virginia is thought by some to be a natural hybrid between the more northern variety and Fraser fir. While red spruce is common in both upland and bog habitats, balsam fir, as well as black spruce and tamarack, are more characteristic of

6642-516: The Glossopteris flora, whose distribution would have ranged from the polar circle to the equator if the continents had been in their present position; similarly, the freshwater reptile Mesosaurus has been found in only localized regions of the coasts of Brazil and West Africa . Geologists can also determine the movement of continental plates by examining the orientation of magnetic minerals in rocks . When rocks are formed, they take on

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6804-628: The Adirondacks . After the Grenville orogeny, the direction of the continental drift reversed, and the single supercontinent Rodinia began to break up. The mountains formed during the Grenvillian era underwent erosion due to weathering, glaciation, and other natural processes, resulting in the leveling of the landscape. The eroded sediments from these mountains contributed to the formation of sedimentary basins and valleys. For example, in what

6966-518: The Alps and the Rockies before natural erosion occurred over the last 240 million years leading to what is present today. The Appalachian Mountains are a barrier to east–west travel, as they form a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west. This barrier was extremely important in shaping the expansion of the United States in

7128-776: The Appalachian Mountains chain extending from the southeastern United States to the Scandinavian Caledonides of Europe; these are now believed to have formed a single chain, the Central Pangean Mountains . Fossil evidence for Pangaea includes the presence of similar and identical species on continents that are now great distances apart. For example, fossils of the therapsid Lystrosaurus have been found in South Africa , India and Antarctica , alongside members of

7290-471: The Appalachians , are a mountain range in eastern to northeastern North America . The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain. The general definition used is one followed by the United States Geological Survey and the Geological Survey of Canada to describe the respective countries' physiographic regions. The U.S. uses

7452-680: The Caledonian orogeny . As Avalonia inched towards Laurentia, the seaway between them, a remnant of the Iapetus Ocean, was slowly shrinking. Meanwhile, southern Europe broke off from Gondwana and began to move towards Euramerica across the Rheic Ocean . It collided with southern Baltica in the Devonian. By the late Silurian, Annamia ( Indochina ) and the South China Craton split from Gondwana and moved northward, shrinking

7614-596: The Coal Region of northeastern Pennsylvania . The bituminous coal fields of western Pennsylvania , western Maryland , southeastern Ohio, eastern Kentucky, southwestern Virginia , and West Virginia contain the sedimentary form of coal. The mountain top removal method of coal mining , in which entire mountain tops are removed, is currently threatening vast areas and ecosystems of the Appalachian Mountain region. The surface coal mining that started in

7776-469: The Early Cretaceous . The opening of the Tethys Ocean also contributed to the warming of the climate. The very active mid-ocean ridges associated with the breakup of Pangaea raised sea levels to the highest in the geological record, flooding much of the continents. The expansion of the temperate climate zones that accompanied the breakup of Pangaea may have contributed to the diversification of

7938-758: The Gulf of Mexico . In the central section, north of the New River, the rivers, rising in or just beyond the Valley Ridges, flow through great gorges to the Great Valley, and then across the Blue Ridge to tidal estuaries penetrating the coastal plain via the Roanoke River, James River , Potomac River , and Susquehanna River . In the northern section the height of land lies on the inland side of

8100-464: The Iapetus Ocean and Paleoasian Ocean. Most of these landmasses coalesced again to form the relatively short-lived supercontinent Pannotia, which included large areas of land near the poles and a small strip connecting the polar masses near the equator. Pannotia lasted until 540  Ma , near the beginning of the Cambrian and then broke up, giving rise to the continents of Laurentia, Baltica, and

8262-734: The Iapetus Ocean , from the North America/Europe collision (See Caledonian orogeny ). By the end of the Mesozoic Era , the Appalachian Mountains had been eroded to an almost flat plain. It was not until the region was uplifted during the Cenozoic Era that the distinctive topography of the present formed. Uplift rejuvenated the streams, which rapidly responded by cutting downward into the ancient bedrock. Some streams flowed along weak layers that define

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8424-785: The Jurassic , completely closing the Proto-Tethys Ocean. By the Early Permian , the Cimmerian plate split from Gondwana and moved towards Laurasia, thus closing the Paleo-Tethys Ocean and forming the Tethys Ocean in its southern end. Most of the landmasses were all in one. By the Triassic , Pangaea rotated a little, and the Cimmerian plate was still travelling across the shrinking Paleo-Tethys until

8586-577: The Jurassic . Pangaea was C-shaped, with the bulk of its mass stretching between Earth 's northern and southern polar regions and surrounded by the superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans . Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists . The name "Pangaea" is derived from Ancient Greek pan ( πᾶν , "all, entire, whole") and Gaia or Gaea ( Γαῖα , " Mother Earth , land"). The first to suggest that

8748-530: The Mesoproterozoic , primarily by lateral accretion of juvenile arcs, and in ~1000 Ma Nuna collided with other land masses, forming Rodinia . Between ~825 and 750 Ma Rodinia broke apart. However, before completely breaking up, some fragments of Rodinia had already come together to form Gondwana by ~608 Ma . Pangaea formed through the collision of Gondwana, Laurasia ( Laurentia and Baltica ), and Siberia . The second model (Kenorland-Arctica)

8910-757: The Middle Jurassic . By the Late Triassic , the Paleo-Tethys had closed from west to east, creating the Cimmerian Orogeny . Pangaea, which looked like a C , with the Tethys Ocean inside the C , had rifted by the Middle Jurassic. Pangaea existed as a supercontinent for 160 million years, from its assembly around 335 Ma (Early Carboniferous) to its breakup 175 Ma (Middle Jurassic). During this interval, important developments in

9072-491: The North American craton . Volcanoes grew along the continental margin coincident with the initiation of subduction . Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. As the mountains rose, erosion began to wear them down over time. Streams carried rock debris downslope to be deposited in nearby lowlands. The Taconic orogeny ended after about 60 million years, but built much of

9234-556: The Rocky Mountains of the west. Some of the outcrops in the Appalachians contain rocks formed during the Precambrian era. The geologic processes that led to the formation of the Appalachian Mountains started 1.1 billion years ago. The first mountain range in the region was created when the continents of Laurentia and Amazonia collided, creating a supercontinent called Rodinia . The collision of these continents caused

9396-570: The Triassic–Jurassic extinction event . These events resulted in disaster fauna showing little diversity and high cosmopolitanism, including Lystrosaurus , which opportunistically spread to every corner of Pangaea following the Permian–Triassic extinction event. On the other hand, there is evidence that many Pangaean species were provincial , with a limited geographical range, despite the absence of geographical barriers. This may be due to

9558-723: The eastern seaboard of the United States and the Midwest region of the country. The Eastern Continental Divide follows the Appalachian Mountains from Pennsylvania to Georgia. The Appalachians, particularly the Central and Southern regions, is one of the most biodiverse places in North America. The north–south orientation of the long ridges and valleys contributes to the high number of plant and animal species. Species were able to migrate through these from either direction during alternating periods of warming and cooling, settling in

9720-1552: The mixed-mesophytic or medium-moisture types, which are largely confined to rich, moist montane soils of the southern and central Appalachians, particularly in the Cumberland and Allegheny Mountains, but also thrive in the southern Appalachian coves. Characteristic canopy species are white basswood ( Tilia heterophylla ), yellow buckeye ( Aesculus octandra ), sugar maple ( Acer saccharum ), American beech ( Fagus grandifolia ), tuliptree ( Liriodendron tulipifera ), white ash ( Fraxinus americana ) and yellow birch ( Betula alleganiensis ). Other common trees are red maple ( Acer rubrum ), shagbark and bitternut hickories ( Carya ovata and C. cordiformis ) and black or sweet birch ( Betula lenta ). Small understory trees and shrubs include paw paw ( Asimina tribola ), flowering dogwood ( Cornus florida ), hophornbeam ( Ostrya virginiana ), witch-hazel ( Hamamelis virginiana ) and spicebush ( Lindera benzoin ). There are also hundreds of perennial and annual herbs, among them such herbal and medicinal plants as American ginseng ( Panax quinquefolius ), goldenseal ( Hydrastis canadensis ), bloodroot ( Sanguinaria canadensis ) and black cohosh ( Cimicifuga racemosa ). The foregoing trees, shrubs, and herbs are also more widely distributed in less rich mesic forests that generally occupy coves, stream valleys and flood plains throughout

9882-403: The upper mantle by replenishing the large-ion lithophile elements , volcanism affects plate movement. The plates will be moved towards a geoidal low perhaps where the slab avalanche occurred and pushed away from the geoidal high that can be caused by the plumes or superplumes. This causes the continents to push together to form supercontinents and was evidently the process that operated to cause

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10044-596: The 1940s has significantly impacted the central Appalachian Mountains in Kentucky , Tennessee , Virginia and West Virginia. Early mining methods were unregulated and mined land reclamation research, including acid base reaction , was led by the West Virginia University in the 1960s and 1970s. West Virginia developed rigorous mine reclamation standards for state coal mines in the late 1960s. Regulations were introduced by most federal states to protect

10206-568: The 96-square-mile (248.6 km ) archipelago of Saint Pierre and Miquelon , an overseas collectivity of France , meaning it is technically in three countries. The highest peak of the mountain range is Mount Mitchell in North Carolina at 6,684 feet (2,037 m), which is also the highest point in the United States east of the Mississippi River . The range is older than the other major mountain range in North America,

10368-564: The Appalachian Basin. Some plateaus of the Appalachian Mountains contain metallic minerals such as iron and zinc . There are many geological issues concerning the rivers and streams of the Appalachians. In spite of the existence of the Great Appalachian Valley, many of the main rivers are transverse to the mountain system axis. The drainage divide of the Appalachians follows a tortuous course that crosses

10530-627: The Appalachian Mountains by the late 1960s. Social and political activism brought about the Surface Mining Control and Reclamation Act of 1977 . The 1859 discovery of commercial quantities of petroleum in the Appalachian Mountains of western Pennsylvania started the modern United States petroleum industry . Recent discoveries of commercial natural gas deposits in the Marcellus Shale formation and Utica Shale formations have once again focused oil industry attention on

10692-605: The Appalachian range in New Brunswick and Quebec . While exploring inland along the northern coast of Florida in 1528, the members of the Narváez expedition , including Álvar Núñez Cabeza de Vaca , found a Native American village near present-day Tallahassee, Florida whose name they transcribed as Apalchen or Apalachen [a.paˈla.tʃɛn] . The name was soon altered by the Spanish to Apalachee and used as

10854-552: The Blue Ridge again reaches 2,000 ft (600 m) and higher. In the Virginia Blue Ridge, the following are some of the highest peaks north of the Roanoke River : Stony Man 4,031 ft (1,229 m), Hawksbill Mountain 4,066 ft (1,239 m), Apple Orchard Mountain 4,225 ft (1,288 m) and Peaks of Otter 4,001 and 3,875 ft (1,220 and 1,181 m). South of the Roanoke River, along

11016-439: The Blue Ridge, are Virginia's highest peaks including Whitetop Mountain 5,520 ft (1,680 m) and Mount Rogers 5,729 ft (1,746 m), the highest point in the Commonwealth. Chief summits in the southern section of the Blue Ridge are located along two main crests, the Western or Unaka Front along the Tennessee - North Carolina border and the Eastern Front in North Carolina, or one of several "cross ridges" between

11178-416: The Cenozoic, including the opening of the Gulf of California , the uplift of the Alps , and the opening of the Sea of Japan . The break-up of Pangaea continues today in the Red Sea Rift and East African Rift . The breakup of Pangaea was accompanied by outgassing of large quantities of carbon dioxide from continental rifts. This produced a Mesozoic CO 2 high that contributed to the very warm climate of

11340-441: The Cretaceous when Laurasia started to rotate clockwise and moved northward with North America to the north, and Eurasia to the south. The clockwise motion of Laurasia led much later to the closing of the Tethys Ocean and the widening of the "Sinus Borealis", which later became the Arctic Ocean . Meanwhile, on the other side of Africa and along the adjacent margins of east Africa, Antarctica and Madagascar , rifts formed that led to

11502-456: The Early Cretaceous, Atlantica , today's South America and Africa, separated from eastern Gondwana. Then in the Middle Cretaceous, Gondwana fragmented to open up the South Atlantic Ocean as South America started to move westward away from Africa. The South Atlantic did not develop uniformly; rather, it rifted from south to north. Also, at the same time, Madagascar and Insular India began to separate from Antarctica and moved northward, opening up

11664-931: The Great Balsams. The Western Blue Ridge Front is subdivided into the Unaka Range , the Bald Mountains , the Great Smoky Mountains , and the Unicoi Mountains , and its major peaks include Roan Mountain 6,285 ft (1,916 m) in the Unakas, Big Bald 5,516 ft (1,681 m) and Max Patch 4,616 ft (1,407 m) in the Bald Mountains, Kuwohi 6,643 ft (2,025 m), Mount Le Conte 6,593 feet (2,010 m), and Mount Guyot 6,621 ft (2,018 m) in

11826-749: The Great Smokies, and Big Frog Mountain 4,224 ft (1,287 m) near the Tennessee- Georgia -North Carolina border. Prominent summits in the cross ridges include Waterrock Knob (6,292 ft (1,918 m)) in the Plott Balsams . Across northern Georgia, numerous peaks exceed 4,000 ft (1,200 m), including Brasstown Bald , the state's highest, at 4,784-and-4,696 ft (1,458-and-1,431 m) Rabun Bald . In north-central Alabama , Mount Cheaha rises prominently to 1,445 feet (440 m) over its surroundings, as part of

11988-623: The Indian Ocean. Madagascar and India separated from each other 100–90 Ma in the Late Cretaceous. India continued to move northward toward Eurasia at 15 centimeters (6 in) per year (a plate tectonic record), closing the eastern Tethys Ocean, while Madagascar stopped and became locked to the African Plate . New Zealand , New Caledonia and the rest of Zealandia began to separate from Australia, moving eastward toward

12150-664: The Latinized form Pangaea , especially during a symposium of the American Association of Petroleum Geologists in November 1926. Wegener originally proposed that the breakup of Pangaea was caused by centripetal forces from Earth's rotation acting on the high continents. However, this mechanism was easily shown to be physically implausible, which delayed acceptance of the Pangaea hypothesis. Arthur Holmes proposed

12312-671: The Pacific and opening the Coral Sea and Tasman Sea . The third major and final phase of the break-up of Pangaea occurred in the early Cenozoic ( Paleocene to Oligocene ). Laurasia split when Laurentia broke from Eurasia, opening the Norwegian Sea about 60–55 Ma. The Atlantic and Indian Oceans continued to expand, closing the Tethys Ocean. Meanwhile, Australia split from Antarctica and moved quickly northward, just as India had done more than 40 million years before. Australia

12474-878: The Proto-Tethys Ocean and opening the Paleo-Tethys Ocean to the south. In the Devonian Gondwana moved towards Euramerica, causing the Rheic Ocean to shrink. In the Early Carboniferous , northwest Africa had touched the southeastern coast of Euramerica, creating the southern portion of the Appalachian Mountains, the Meseta Mountains , and the Mauritanide Mountains , an event called the Variscan orogeny . South America moved northward to southern Euramerica, while

12636-402: The Protopangea–Paleopangea solution implies that Phanerozoic style of supercontinent cycles did not operate during these times. Also, there are instances where these secular trends have a weak, uneven, or absent imprint on the supercontinent cycle; secular methods for supercontinent reconstruction will produce results that have only one explanation, and each explanation for a trend must fit in with

12798-481: The South Pole may have reached freezing, there were no ice sheets during the early Silurian (~443.8 Ma) through the late Mississippian (~330.9 Ma). Agreement can be met with the theory that continental snow can occur when the edge of a continent is near the pole. Therefore Gondwana, although located tangent to the South Pole, may have experienced glaciation along its coasts. Though precipitation rates during monsoonal circulations are difficult to predict, there

12960-594: The U.S./Canadian border, the St. Lawrence Valley area is handled differently in the physiographic classification schemas. The part of the St. Lawrence Valley in the United States is one of the second-level classifications, part of the Appalachian Highlands. In Canada, the area is part of the first-level classification, the St. Lawrence Lowlands . This includes the area around the city of Montreal, Anticosti Island , and

13122-399: The accretion and dispersion of supercontinents is seen in the geological rock record. The influence of known volcanic eruptions does not compare to that of flood basalts . The timing of flood basalts has corresponded with a large-scale continental break-up. However, due to a lack of data on the time required to produce flood basalts, the climatic impact is difficult to quantify. The timing of

13284-415: The angiosperms. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Supercontinent Moving under

13446-400: The break-up of supercontinents and die during supercontinent assembly. Pangaea's supercontinent cycle is a good example of the efficiency of using the presence or lack of these entities to record the development, tenure, and break-up of supercontinents. There is a sharp decrease in passive margins between 500 and 350 Ma during the timing of Pangaea's assembly. The tenure of Pangaea is marked by

13608-414: The breakup of Precambrian supercontinents and the lack of land plants as a carbon sink . During the late Permian, it is expected that seasonal Pangaean temperatures varied drastically. Subtropic summer temperatures were warmer than that of today by as much as 6–10 degrees, and mid-latitudes in the winter were less than −30 degrees Celsius. These seasonal changes within the supercontinent were influenced by

13770-422: The climate of the planet drastically, with supercontinents having a larger, more prevalent influence. Continents modify global wind patterns, control ocean current paths, and have a higher albedo than the oceans. Winds are redirected by mountains, and albedo differences cause shifts in onshore winds. Higher elevation in continental interiors produces a cooler, drier climate, the phenomenon of continentality . This

13932-641: The colonial era. The range is the home of a very popular recreational feature, the Appalachian Trail . This is a 2,175-mile (3,500 km) hiking trail that runs all the way from Mount Katahdin in Maine to Springer Mountain in Georgia , passing over or past a large part of the Appalachian range. The International Appalachian Trail is an extension of this hiking trail into the Canadian portion of

14094-684: The consumption of CO 2 . Even though during the Archaean solar radiation was reduced by 30 percent and the Cambrian - Precambrian boundary by 6 percent, the Earth has only experienced three ice ages throughout the Precambrian. Erroneous conclusions are more likely to be made when models are limited to one climatic configuration (which is usually present-day). Cold winters in continental interiors are due to rate ratios of radiative cooling (greater) and heat transport from continental rims. To raise winter temperatures within continental interiors,

14256-456: The contemporary Earth became dominant only during the latter part of geological times. This approach was widely criticized by many researchers as it uses incorrect application of paleomagnetic data. A supercontinent cycle is the break-up of one supercontinent and the development of another, which takes place on a global scale. Supercontinent cycles are not the same as the Wilson cycle , which

14418-457: The continent that are now exposed. The first mountain-building tectonic plate collision that initiated the construction of what are today the Appalachians occurred at least a billion years ago when the pre-North American craton called Laurentia collided with at least one other craton - Amazonia . All the other cratons of the earth also collided at about this time to form the supercontinent Rodinia and were surrounded by one single ocean. (It

14580-591: The continents that were ancestral to North America and Africa collided during the formation of the supercontinent Pangea . Because North America and Africa were once geographically connected, the Appalachians formed part of the same mountain chain as the Little Atlas in Morocco . This mountain range, known as the Central Pangean Mountains , extended into Scotland , before the Mesozoic Era opening of

14742-526: The continents were once joined and later separated may have been Abraham Ortelius in 1596. The concept that the continents once formed a contiguous land mass was hypothesised, with corroborating evidence, by Alfred Wegener , the originator of the scientific theory of continental drift , in three 1912 academic journal articles written in German titled Die Entstehung der Kontinente ( The Origin of Continents ). He expanded upon his hypothesis in his 1915 book of

14904-412: The deciduous needle-leaf conifer, the tamarack , or eastern larch ( Larix laricina ). The dominant northern and high elevation conifer is the red spruce ( Picea rubens ), which grows from near sea level to above 4,000 ft (1,200 m) above sea level (asl) in northern New England and southeastern Canada. It also grows southward along the Appalachian crest to the highest elevations of

15066-529: The driest sites are dominated by chestnut oak, or sometimes by scarlet or northern red oaks. In the northern Appalachians the oaks, except for white and northern red, drop out, while the latter extends farthest north. The oak forests generally lack the diverse small tree, shrub and herb layers of mesic forests. Shrubs are generally ericaceous , and include the evergreen mountain laurel ( Kalmia latifolia ), various species of blueberries ( Vaccinium spp.), black huckleberry ( Gaylussacia baccata ),

15228-416: The early continental crust to aggregate into Protopangea. Dispersal of supercontinents is caused by the accumulation of heat underneath the crust due to the rising of very large convection cells or plumes, and a massive heat release resulted in the final break-up of Paleopangea. Accretion occurs over geoidal lows that can be caused by avalanche slabs or the downgoing limbs of convection cells. Evidence of

15390-523: The eastern part, and the western part is the Appalachian Mountains , uplifted in the early Permian . (The existence of a flat elevated plateau like the Tibetan Plateau is under debate.) The locality of the Variscan range made it influential to both the northern and southern hemispheres. The elevation of the Appalachians would greatly influence global atmospheric circulation. Continents affect

15552-494: The eastern portion of Gondwana ( India , Antarctica , and Australia ) headed toward the South Pole from the equator. North and South China were on independent continents. The Kazakhstania microcontinent had collided with Siberia. (Siberia had been a separate continent for millions of years since the breakup of Pannotia.) The Variscan orogeny raised the Central Pangaean Mountains, which were comparable to

15714-440: The environment throughout time. Phanerozoic (541 Ma to present) and Precambrian ( 4.6 Ga to 541 Ma ) had primarily passive margins and detrital zircons (and orogenic granites ), whereas the tenure of Pangaea contained few. Matching edges of continents are where passive margins form. The edges of these continents may rift . At this point, seafloor spreading becomes the driving force. Passive margins are therefore born during

15876-621: The equator. The assembly of Pangaea disrupted the Intertropical Convergence Zone and created an extreme monsoon climate that reduced the deposition of coal to its lowest level in the last 300 million years. During the Permian , coal deposition was largely restricted to the North and South China microcontinents, which were among the few areas of continental crust that had not joined with Pangaea. The extremes of climate in

16038-514: The evolution of life took place. The seas of the Early Carboniferous were dominated by rugose corals , brachiopods , bryozoans , sharks , and the first bony fish . Life on land was dominated by lycopsid forests inhabited by insects and other arthropods and the first tetrapods . By the time Pangaea broke up, in the Middle Jurassic, the seas swarmed with molluscs (particularly ammonites ), ichthyosaurs , sharks and rays, and

16200-435: The existence of Pangaea. The seemingly close fit of the coastlines of North and South America with Europe and Africa was remarked on almost as soon as these coasts were charted. Careful reconstructions showed that the mismatch at the 500 fathoms (3,000 feet; 910 meters) contour was less than 130 km (81 mi), and it was argued that this was much too similar to be attributed to coincidence. Additional evidence for Pangaea

16362-418: The few continental areas not merged with Pangaea, as a refugium. There were three major phases in the break-up of Pangaea. The Atlantic Ocean did not open uniformly; rifting began in the north-central Atlantic. The first breakup of Pangaea is proposed for the late Ladinian (230 Ma) with initial spreading in the opening central Atlantic. Then the rifting proceeded along the eastern margin of North America,

16524-443: The first ray-finned bony fishes, while life on land was dominated by forests of cycads and conifers in which dinosaurs flourished and in which the first true mammals had appeared. The evolution of life in this time reflected the conditions created by the assembly of Pangaea. The union of most of the continental crust into one landmass reduced the extent of sea coasts. Increased erosion from uplifted continental crust increased

16686-425: The folds and faults created many millions of years earlier. Other streams downcut so rapidly that they cut right across the resistant folded rocks of the mountain core, carving canyons across rock layers and geologic structures. The Appalachian Mountains contain major deposits of anthracite coal as well as bituminous coal . In the folded mountains the coal is in metamorphosed form as anthracite , represented by

16848-419: The forces of plate tectonics , supercontinents have assembled and dispersed multiple times in the geologic past. According to modern definitions, a supercontinent does not exist today; the closest is the current Afro-Eurasian landmass, which covers approximately 57% of Earth's total land area. The last period in which the continental landmasses were near to one another was 336 to 175 million years ago, forming

17010-693: The formation of the Ural Mountains and Laurasia . This was the last step of the formation of Pangaea. Meanwhile, South America had collided with southern Laurentia, closing the Rheic Ocean and completing the Variscian orogeny with the formation the southernmost part of the Appalachians and Ouachita Mountains . By this time, Gondwana was positioned near the South Pole, and glaciers formed in Antarctica, India, Australia, southern Africa, and South America. The North China Craton collided with Siberia by

17172-550: The formation of the southwestern Indian Ocean in the Cretaceous. The second major phase in the break-up of Pangaea began in the Early Cretaceous (150–140 Ma), when Gondwana separated into multiple continents (Africa, South America, India, Antarctica, and Australia). The subduction at Tethyan Trench probably caused Africa, India and Australia to move northward, causing the opening of a "South Indian Ocean". In

17334-712: The gaps. These detrital zircons are taken from the sands of major modern rivers and their drainage basins . Oceanic magnetic anomalies and paleomagnetic data are the primary resources used for reconstructing continent and supercontinent locations back to roughly 150 Ma. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Appalachian Mountains The Appalachian Mountains , often called

17496-495: The importance of floodplain and delta environments relative to shallow marine environments. Continental assembly and uplift also meant increasingly arid land climates, favoring the evolution of amniote animals and seed plants , whose eggs and seeds were better adapted to dry climates. The early drying trend was most pronounced in western Pangaea, which became a center of the evolution and geographical spread of amniotes. Coal swamps typically form in perpetually wet regions close to

17658-483: The interior of Pangaea are reflected in bone growth patterns of pareiasaurs and the growth patterns in gymnosperm forests. The lack of oceanic barriers is thought to have favored cosmopolitanism , in which successful species attain wide geographical distribution. Cosmopolitanism was also driven by mass extinctions , including the Permian–Triassic extinction event , the most severe in the fossil record, and also

17820-474: The lack of iron formations may have been the result of an increase in oxygen. The fourth oxygenation event, roughly 0.6 Ga, is based on modeled rates of sulfur isotopes from marine carbonate-associated sulfates . An increase (near doubled concentration) of sulfur isotopes, which is suggested by these models, would require an increase in the oxygen content of the deep oceans. Between 650 and 550 Ma there were three increases in ocean oxygen levels, this period

17982-485: The land mass that is now New England and southwestward to Pennsylvania. The Taconic Orogeny was the second of four mountain building plate collisions that contributed to the formation of the Appalachians, culminating in the collision of North America and Africa (see Alleghanian orogeny ). The third mountain-building event was the Acadian orogeny which occurred between 375 and 359 million years ago. The Acadian orogeny

18144-467: The large size of Pangaea. And, just like today, coastal regions experienced much less variation. During the Jurassic, summer temperatures did not rise above zero degrees Celsius along the northern rim of Laurasia, which was the northernmost part of Pangaea (the southernmost portion of Pangaea was Gondwana). Ice-rafted dropstones sourced from Russia are indicators of this northern boundary. The Jurassic

18306-552: The later supercontinents, Pannotia and Pangaea. According to one reconstruction, when Rodinia broke up, it split into three pieces: proto- Laurasia , proto-Gondwana, and the smaller Congo Craton . Proto-Laurasia and proto-Gondwana were separated by the Proto-Tethys Ocean . Proto-Laurasia split apart to form the continents of Laurentia , Siberia , and Baltica . Baltica moved to the east of Laurentia, and Siberia moved northeast of Laurentia. The split created two oceans,

18468-436: The latitude and orientation of ancient continental blocks, and newer techniques may help determine longitudes. Paleontology helps determine ancient climates, confirming latitude estimates from paleomagnetic measurements, and the distribution of ancient forms of life provides clues on which continental blocks were close to each other at particular geological moments. However, reconstructions of continents prior to Pangaea, including

18630-469: The latter. However, balsam fir also does well in soils with a pH as high as 6. Eastern or Canada hemlock ( Tsuga canadensis ) is another important evergreen needle-leaf conifer that grows along the Appalachian chain from north to south but is confined to lower elevations than red spruce and the firs. It generally occupies richer and less acidic soils than the spruce and firs and is characteristic of deep, shaded and moist mountain valleys and coves . It

18792-466: The magnetic orientation of the Earth, showing which direction the poles lie relative to the rock; this determines latitudes and orientations (though not longitudes). Magnetic differences between samples of sedimentary and intrusive igneous rock whose age varies by millions of years is due to a combination of magnetic polar wander (with a cycle of a few thousand years) and the drifting of continents over millions of years. The polar wander component, which

18954-433: The mass amounts of nutrients, including iron and phosphorus , would have washed into oceans, just as is seen happening today. The oceans would then be rich in nutrients essential to photosynthetic organisms, which would then be able to respire mass amounts of oxygen. There is an apparent direct relationship between orogeny and the atmospheric oxygen content. There is also evidence for increased sedimentation concurrent with

19116-540: The microclimates that best suited them. The flora of the Appalachians are diverse and vary primarily in response to geology, latitude, elevation and moisture availability. Geobotanically, they constitute a floristic province of the North American Atlantic Region . The Appalachians consist primarily of deciduous broad-leaf trees and evergreen needle-leaf conifers, but also contain the evergreen broad-leaf American holly ( Ilex opaca ), and

19278-544: The modern Himalayas in scale. With Pangaea stretching from the South Pole across the equator and well into the Northern Hemisphere, an intense megamonsoon climate was established, except for a perpetually wet zone immediately around the central mountains. Western Kazakhstania collided with Baltica in the late Carboniferous, closing the Ural Ocean and the western Proto-Tethys ( Uralian orogeny ), causing

19440-788: The more notable peaks in West Virginia. The Blue Ridge Mountains , rising in southern Pennsylvania and there known as South Mountain , attain elevations of about 2,000 ft (600 m) in Pennsylvania. South Mountain achieves its highest point just below the Mason-Dixon line in Maryland at Quirauk Mountain 2,145 ft (654 m) and then diminishes in height southward to the Potomac River . Once in Virginia ,

19602-555: The more plausible mechanism of mantle convection , which, together with evidence provided by the mapping of the ocean floor following the Second World War , led to the development and acceptance of the theory of plate tectonics . This theory provides the widely-accepted explanation for the existence and breakup of Pangaea. The geography of the continents bordering the Atlantic Ocean was the first evidence suggesting

19764-787: The mountainous belt just north of the New River in Virginia. South of the New River, rivers head into the Blue Ridge, cross the higher Unakas, receive important tributaries from the Great Valley, and traversing the Cumberland Plateau in spreading gorges ( water gaps ), escape by way of the Cumberland River and the Tennessee River rivers to the Ohio River and the Mississippi River, and thence to

19926-550: The mountainous belt, and thus the main lines of drainage run from north to south, exemplified by the Hudson River . However, the valley through which the Hudson River flows was cut by the gigantic glaciers of the ice ages —the same glaciers that deposited their terminal moraines in southern New York and formed the east–west Long Island . The Appalachian region is generally considered the geographical divide between

20088-484: The next 250 million years. The Phanerozoic supercontinent Pangaea began to break up 215 Ma and this distancing continues today. Because Pangaea is the most recent of Earth's supercontinents, it is the best known and understood. Contributing to Pangaea's popularity in the classroom, its reconstruction is almost as simple as fitting together the present continents bordering the Atlantic ocean like puzzle pieces. For

20250-572: The northern Appalachians. Siberia sat near Euramerica, with the Khanty Ocean between the two continents. While all this was happening, Gondwana drifted slowly towards the South Pole. This was the first step of the formation of Pangaea. The second step in the formation of Pangaea was the collision of Gondwana with Euramerica. By the middle of the Silurian , 430 Ma, Baltica had already collided with Laurentia, forming Euramerica, an event called

20412-690: The northwest African margin and the High , Saharan and Tunisian Atlas Mountains . Another phase began in the Early-Middle Jurassic (about 175 Ma), when Pangaea began to rift from the Tethys Ocean in the east to the Pacific Ocean in the west. The rifting that took place between North America and Africa produced multiple failed rifts . One rift resulted in the North Atlantic Ocean. The South Atlantic did not open until

20574-531: The northwest coastline of Newfoundland. The dissected plateau area, while not actually made up of geological mountains, is popularly called "mountains", especially in eastern Kentucky and West Virginia, and while the ridges are not high, the terrain is extremely rugged. In Ohio and New York, some of the plateau has been glaciated , which has rounded off the sharp ridges and filled the valleys to some extent. The glaciated regions are usually referred to as hill country rather than mountains. The Appalachian belt includes

20736-513: The number of islands that could have served as refugia for marine species. Species diversity may have already been reduced prior to mass extinction events due to mingling of species possible when formerly separate continents were merged. However, there is strong evidence that climate barriers continued to separate ecological communities in different parts of Pangaea. The eruptions of the Emeishan Traps may have eliminated South China, one of

20898-424: The oceans, but there were no plants or animals on land. Then, during the middle Ordovician Period about 500 to 470 million years ago, the motion of the crustal plates changed, and the continents began to move back toward each other. The once-quiet Appalachian passive margin changed to a very active plate boundary when a neighboring Iapetus oceanic plate containing a volcanic arc collided with and began sinking beneath

21060-546: The ones in this section, remain partially speculative, and different reconstructions will differ in some details. The fourth-last supercontinent, called Columbia or Nuna, appears to have assembled in the period 2.0–1.8 billion years ago (Ga) . Columbia/Nuna broke up, and the next supercontinent, Rodinia , formed from the accretion and assembly of its fragments. Rodinia lasted from about 1.3 billion years ago until about 750 million years ago, but its configuration and geodynamic history are not nearly as well understood as those of

21222-472: The period before Pangaea, there are two contrasting models for supercontinent evolution through geological time . The first model theorizes that at least two separate supercontinents existed comprising Vaalbara and Kenorland , with Kenorland comprising Superia and Sclavia . These parts of Neoarchean age broke off at ~2480 and 2312 Ma , and portions of them later collided to form Nuna (Northern Europe and North America). Nuna continued to develop during

21384-738: The plateaus sloping southward to the Atlantic Ocean in New England , and southeastward to the border of the coastal plain through the central and southern Atlantic states; and on the northwest, the Allegheny and Cumberland plateaus declining toward the Great Lakes and the interior plains. A remarkable feature of the belt is the longitudinal chain of broad valleys, including the Great Appalachian Valley , which in

21546-479: The rate of heat transport must increase to become greater than the rate of radiative cooling. Through climate models, alterations in atmospheric CO 2 content and ocean heat transport are not comparatively effective. CO 2 models suggest that values were low in the late Cenozoic and Carboniferous-Permian glaciations. Although early Paleozoic values are much larger (more than 10 percent higher than that of today). This may be due to high seafloor spreading rates after

21708-527: The reconstruction. During the intervening periods, the poles conform to a unified apparent polar wander path. Although it contrasts the first model, the first phase (Protopangea) essentially incorporates Vaalbara and Kenorland of the first model. The explanation for the prolonged duration of the Protopangea–Paleopangea supercontinent appears to be that lid tectonics (comparable to the tectonics operating on Mars and Venus) prevailed during Precambrian times. According to this theory, plate tectonics as seen on

21870-417: The reduced area of continental shelf environments may have left marine species vulnerable to extinction. However, no evidence for a species-area effect has been found in more recent and better characterized portions of the geologic record. Another possibility is that reduced seafloor spreading associated with the formation of Pangaea, and the resulting cooling and subsidence of oceanic crust , may have reduced

22032-601: The region level. The lowest level of classification is "section". The Appalachian Uplands are one of the seven physiographic divisions in Canada . Canada's GSC does not use the same classification system as the USGS below the division level. The agency does break the divisions of the Appalachian Uplands into 13 subsections that are in four different political provinces of Canada. While the Appalachian Highlands and Appalachian Uplands are generally continuous across

22194-454: The residents of the regions regarding the correct pronunciation. Elsewhere, a commonly accepted pronunciation for the adjective Appalachian is / ˌ æ p ə ˈ l æ tʃ i ə n / , with the last two syllables "-ian" pronounced as in the word "Romanian". Perhaps partly because the range runs through large portions of both the United States and Canada, and partly because the range was formed over numerous geologic time periods, one of which

22356-557: The rest. The following table names reconstructed ancient supercontinents, using Bradley's 2011 looser definition, with an approximate timescale of millions of years ago (Ma). The causes of supercontinent assembly and dispersal are thought to be driven by convection processes in Earth's mantle . Approximately 660 km into the mantle, a discontinuity occurs, affecting the surface crust through processes involving plumes and superplumes (aka large low-shear-velocity provinces ). When

22518-488: The result of volcanic activity that occurred around this time. Evidence of subsurface activity, dikes and sills intruding into the overlying rock, is present in the Blue Ridge as well. For instance, mafic rocks have been found along the Fries Fault in the central Blue Ridge area of Montgomery County, VA. The Iapetus continued to expand and during that time bacteria, algae, and many species of invertebrates flourished in

22680-471: The rock record. Their fluctuations correlate with Precambrian supercontinent cycles. The U–Pb zircon dates from orogenic granites are among the most reliable aging determinants. Some issues exist with relying on granite sourced zircons, such as a lack of evenly globally sourced data and the loss of granite zircons by sedimentary coverage or plutonic consumption. Where granite zircons are less adequate, detrital zircons from sandstones appear and make up for

22842-466: The rocks to be folded and faulted, creating the first mountains in the region. Many of the rocks and minerals that were formed during that event can currently be seen at the surface of the present Appalachian range. Around 480 million years ago, geologic processes began that led to three distinct orogenic eras that created much of the surface structure seen in today's Appalachians. During this period, mountains once reached elevations similar to those of

23004-725: The same side of the Great Valley, south of the Potomac, are the Pinnacle 3,007 feet (917 m) and Pidgeon Roost 3,400 ft (1,000 m). In West Virginia, more than 150 peaks rise above 4,000 ft (1,200 m), including Spruce Knob 4,863 ft (1,482 m), the highest point in the Allegheny Mountains . A number of other points in the state rise above 4,800 ft (1,500 m). Cheat Mountain ( Snowshoe Mountain ) at Thorny Flat 4,848 ft (1,478 m) and Bald Knob 4,842 ft (1,476 m) are among

23166-662: The same title, in which he postulated that, before breaking up and drifting to their present locations, all the continents had formed a single supercontinent that he called the Urkontinent . Wegener used the name "Pangaea" once in the 1920 edition of his book, referring to the ancient supercontinent as "the Pangaea of the Carboniferous". He used the Germanized form Pangäa , but the name entered German and English scientific literature (in 1922 and 1926, respectively) in

23328-409: The same trend as the system itself. None of the summits reaches the region of perpetual snow. In Pennsylvania , there are over sixty summits that rise over 2,500 ft (800 m); the summits of Mount Davis and Blue Knob rise over 3,000 ft (900 m). In Maryland, Eagle Rock and Dans Mountain are conspicuous points reaching 3,162 and 2,882 ft (964 and 878 m) respectively. On

23490-591: The second period of oxygenation occurred, which has been called the 'great oxygenation event.' Evidence supporting this event includes red beds appearance 2.3 Ga (meaning that Fe was being produced and became an important component in soils). The third oxygenation stage approximately 1.8 Ga is indicated by the disappearance of iron formations. Neodymium isotopic studies suggest that iron formations are usually from continental sources, meaning that dissolved Fe and Fe had to be transported during continental erosion. A rise in atmospheric oxygen prevents Fe transport, so

23652-487: The southerly sections divides the mountain system into two unequal portions, but in the northernmost lies west of all the ranges possessing typical Appalachian features, and separates them from the Adirondack group. The mountain system has no axis of dominating altitudes, but in every portion, the summits rise to rather uniform heights, and, especially in the central section, the various ridges and intermontane valleys have

23814-462: The southern British Isles , and parts of Belgium , northern France , Nova Scotia , New England , South Iberia , and northwest Africa—broke free from Gondwana and began its journey to Laurentia. Baltica, Laurentia, and Avalonia all came together by the end of the Ordovician to form a landmass called Euramerica or Laurussia, closing the Iapetus Ocean. The collision resulted in the formation of

23976-416: The southern Appalachians, as in North Carolina and Tennessee . In the central Appalachians it is usually confined above 3,000 ft (900 m) asl, except for a few cold valleys in which it reaches lower elevations. In the southern Appalachians, it is restricted to higher elevations. Another species is the black spruce ( Picea mariana ), which extends farthest north of any conifer in North America,

24138-413: The southern and central Appalachians consist largely of black , northern red , white , chestnut and scarlet oaks ( Quercus velutina, Q. rubra, Q. alba, Q. prinus and Q. coccinea ) and hickories, such as the pignut ( Carya glabra ) in particular. The richest forests, which grade into mesic types, usually in coves and on gentle slopes, have predominantly white and northern red oaks, while

24300-511: The southern and central Appalachians at low and intermediate elevations. In the northern Appalachians and at higher elevations of the central and southern Appalachians these diverse mesic forests give way to less diverse northern hardwood forests with canopies dominated only by American beech, sugar maple, American basswood ( Tilia americana ) and yellow birch and with far fewer species of shrubs and herbs. Drier and rockier uplands and ridges are occupied by oak–chestnut forests dominated by

24462-410: The southern regions of the Appalachians, the word is pronounced / ˌ æ p ə ˈ l æ tʃ ɪ n z / , with the third syllable sounding like "latch". In northern parts of the mountain range, it is pronounced / ˌ æ p ə ˈ l eɪ tʃ ɪ n z / or / ˌ æ p ə ˈ l eɪ ʃ ɪ n z / ; the third syllable is like "lay", and the fourth "chins" or "shins". There is often great debate between

24624-432: The southern supercontinent Gondwana . In the Cambrian, Laurentia—which would later become North America —sat on the equator with three bordering oceans: the Panthalassic Ocean to the north and west, the Iapetus Ocean to the south, and the Khanty Ocean to the east. In the early Ordovician , around 480 Ma, the microcontinent Avalonia —a landmass incorporating fragments of what would become eastern Newfoundland ,

24786-472: The southernmost spur of the Blue Ridge Mountains. Sources written prior to the recognition of the concept of physiographic regions divided the Appalachian Mountains into three major sections: Plate tectonics over the period dating back at least 1 billion years led to geological creation of the land that is now the Appalachian Mountain range. The continental movement led to collisions that built mountains and they later pulled apart creating oceans over parts of

24948-454: The strong variations in climate by latitude and season produced by the extreme monsoon climate. For example, cold-adapted pteridosperms (early seed plants) of Gondwana were blocked from spreading throughout Pangaea by the equatorial climate, and northern pteridosperms ended up dominating Gondwana in the Triassic. The tectonics and geography of Pangaea may have worsened the Permian–Triassic extinction event or other mass extinctions. For example,

25110-427: The supercontinent Pangaea . The positions of continents have been accurately determined back to the early Jurassic , shortly before the breakup of Pangaea. Pangaea's predecessor Gondwana is not considered a supercontinent under the first definition since the landmasses of Baltica , Laurentia and Siberia were separate at the time. A future supercontinent, termed Pangaea Proxima , is hypothesized to form within

25272-445: The supercontinent Pangaea. Climate modeling shows that summer fluctuations varied 14–16 degrees Celsius on Pangaea, which is similar or slightly higher than summer temperatures of Eurasia during the Pleistocene. The largest-amplitude Milankovitch cycles are expected to have been at mid-to high-latitudes during the Triassic and Jurassic. Plate tectonics and the chemical composition of the atmosphere (specifically greenhouse gases ) are

25434-403: The suture zone. Intracratonic orogenic belts occur as thrust belts and do not contain any oceanic material. However, the absence of ophiolites is not strong evidence for intracratonic belts, because the oceanic material can be squeezed out and eroded away in an intracratonic environment. The third kind of orogenic belt is a confined orogenic belt which is the closure of small basins. The assembly of

25596-415: The term Appalachian Highlands and Canada uses the term Appalachian Uplands ; the Appalachian Mountains are not synonymous with the Appalachian Plateau , which is one of the provinces of the Appalachian Highlands. The Appalachian range runs from the Island of Newfoundland in Canada, 2,050 mi (3,300 km) southwestward to Central Alabama in the United States; south of Newfoundland, it crosses

25758-485: The timing of these mass oxygenation events, meaning that the organic carbon and pyrite at these times were more likely to be buried beneath sediment and therefore unable to react with the free oxygen. This sustained the atmospheric oxygen increases. At 2.65 Ga there was an increase in molybdenum isotope fractionation. It was temporary but supports the increase in atmospheric oxygen because molybdenum isotopes require free oxygen to fractionate. Between 2.45 and 2.32 Ga,

25920-434: The two main crests. Major subranges of the Eastern Front include the Black Mountains , Great Craggy Mountains , and Great Balsam Mountains , and its chief summits include Grandfather Mountain 5,964 ft (1,818 m) near the Tennessee-North Carolina border, Mount Mitchell 6,684 ft (2,037 m) in the Blacks, and Black Balsam Knob 6,214 ft (1,894 m) and Cold Mountain 6,030 ft (1,840 m) in

26082-422: The two most prevailing factors present within the geologic time scale. Continental drift influences both cold and warm climatic episodes. Atmospheric circulation and climate are strongly influenced by the location and formation of continents and supercontinents. Therefore, continental drift influences mean global temperature. Oxygen levels of the Archaean were negligible, and today they are roughly 21 percent. It

26244-467: Was caused by a series of collisions of pieces of crust from the Avalonia Terrane, sections broken off from continent of Gondwana , with the North American Plate. The collision initiating this orogeny resulted in the closing of the southern Iapetus Ocean and the formation of a high mountain belt. After the Acadian collision took place, Gondwana began to retreat from Laurentia with the newly accreted Avalonian terranes left behind. As Gondwana moved away,

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