Mountain chain

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The Karavanks, a single, long mountain chain. This is the Koschuta ridge near Zell, Carinthia Zell-Pfarre Peiner Kobla 01.jpg
The Karavanks, a single, long mountain chain. This is the Koschuta ridge near Zell, Carinthia

A mountain chain is a row of high mountain summits, a linear sequence of interconnected or related mountains, [1] or a contiguous ridge of mountains within a larger mountain range. The term is also used for elongated fold mountains with several parallel chains ("chain mountains").

Mountain range A geographic area containing several geologically related mountains

A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

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While in mountain ranges, the term mountain chain is common, in hill ranges a sequence of hills tends to be referred to a ridge or hill chain.

Hill Landform that extends above the surrounding terrain

A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, although in areas with scarp/dip topography a hill may refer to the particular section of flat terrain without a massive summit.

Ridge A geological feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance

A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. The sides of the ridge slope away from narrow top on either side. The lines along the crest formed by the highest points, with the terrain dropping down on either sides, are called the ridgelines. Ridges are usually termed hills or mountains as well, depending on size.

Hill chain elongated line of hills

A hill chain, sometimes also hill ridge, is an elongated line of hills that usually includes a succession of more or less prominent hilltops, domed summits or kuppen, hill ridges and saddles and which, together with its associated lateral ridges and branches, may form a complex topographic structure. It may occur within a hill range, within an area of low rolling hill country or on a plain. It may link two or more otherwise distinct hill ranges. The transition from a hill chain to a mountain chain is blurred and depends on regional definitions of a hill or mountain. For example, in the UK and Ireland a mountain must officially be 600 m (2,000 ft) or higher, whereas in North America mountains are often (unofficially) taken as being 1,000 ft (300 m) high or more.

Elongated mountain chains occur most frequently in the orogeny of fold mountains, (that are folded by lateral pressure), and nappe belts (where a sheetlike body of rock has been pushed over another rock mass). Other types of range such as horst ranges, fault block mountain or truncated uplands rarely form parallel mountain chains. However, if a truncated upland is eroded into a high table land, the incision of valleys can lead to the formations of mountain or hill chains.

Orogeny The formation of mountain ranges

An orogeny is an event that leads to both structural deformation and compositional differentiation of the Earth's lithosphere at convergent plate margins. An orogen or orogenic belt develops when a continental plate crumples and is pushed upwards to form one or more mountain ranges; this involves a series of geological processes collectively called orogenesis.

Nappe A large sheetlike body of rock that has been moved a considerable distance above a thrust fault

In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than 2 km (1.2 mi) or 5 km (3.1 mi) above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones. Nappes form when a mass of rock is forced over another rock mass, typically on a low angle fault plane. The resulting structure may include large-scale recumbent folds, shearing along the fault plane, imbricate thrust stacks, fensters and klippe.

Horst (geology) A raised fault block bounded by normal faults

In physical geography and geology, a horst is a raised fault block bounded by normal faults. A horst is a raised block of the Earth's crust that has lifted, or has remained stationary, while the land on either side (graben) has subsided. The word Horst in Dutch and German means heap – cognate with English "hurst".

Formation of parallel mountain chains

In this satellite image of the Alps, the snow limit picks out the individual mountain chains Satellitenaufnahme der Alpen.jpg
In this satellite image of the Alps, the snow limit picks out the individual mountain chains
A view of the Balkan Mountains chain Tsentralen Balkan.jpg
A view of the Balkan Mountains chain

The chain-like arrangement of summits and the formation of long, jagged mountain crests – known in Spanish as sierras ("saws") – is a consequence of their collective formation by mountain building forces. The often linear structure is linked to the direction of these thrust forces and the resulting mountain folding which in turn relates to the fault lines in the upper part of the earth's crust, that run between the individual mountain chains. In these fault zones, the rock, which has sometimes been pulverised, is easily eroded, so that large river valleys are carved out. These, so called longitudinal valleys reinforce the trend, during the early mountain building phase, towards the formation of parallel chains of mountains.

Earths crust crust

The Earth's crust is a thin shell on the outside of the Earth, accounting for less than 1% of Earth's volume. It is the top component of lithosphere: a division of Earth's layers that includes the crust and the upper part of the mantle. The lithosphere is broken into tectonic plates that move, allowing heat to escape from the interior of the Earth into space.

River Natural flowing watercourse

A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek, but not always: the language is vague.

Longitudinal valley

A longitudinal valley is an elongated valley found between two almost parallel mountain chains in geologically young fold mountains such as the Alps, Carpathians, Andes or the highlands of Central Asia. They are often occupied and shaped by a subsequent stream. The term is frequently used if a mountain range also has prominent transverse valleys, where rivers cut through the mountain chains in so-called water gaps.

The tendency, especially of fold mountains (e. g. the Cordilleras) to produce roughly parallel chains is due to their rock structure and the propulsive forces of plate tectonics. The uplifted rock masses are either magmatic plutonic rocks, easily shaped because of their higher temperature, or sediments or metamorphic rocks, which have a less robust structure, that are deposited in the synclines. As a result of orogenic movements, strata of folded rock are formed that are crumpled out of their original horizontal plane and thrust against one another. The longitudinal stretching of the folds takes place at right angles to the direction of the lateral thrusting. The overthrust folds of a nappe belt (e.g. the Central Alps) are formed in a similar way.

Plate tectonics The scientific theory that describes the large-scale motions of Earths lithosphere

Plate tectonics is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere, since tectonic processes began on Earth between 3.3 and 3.5 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s.

Sediment Particulate solid matter that is deposited on the surface of land

Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation. If buried, they may eventually become sandstone and siltstone through lithification.

Metamorphic rock Rock which was subjected to heat and pressure causing profound physical or chemical change

Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat and pressure, causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock.

Although the fold mountains, chain mountains and nappe belts around the world were formed at different times in the earth's history, all during their initial mountain building phases, they are nevertheless morphologically similar. Harder rock forms continuous arêtes or ridges that follow the strike of the beds and folds. The mountain chains or ridges therefore run approximately parallel to one another. They are only interrupted by short, usually narrow, transverse valleys, which often form water gaps. During the course of earth history, erosion by water, ice and wind carried away the highest points of the mountain crests and carved out individual summits or summit chains. Between them, notches were formed that, depending on altitude and rock-type, form knife-edged cols or gentler mountain passes and saddles.

Arête A narrow ridge of rock which separates two valleys

An arête is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequently this results in a saddle-shaped pass, called a col. The edge is then sharpened by freeze-thaw weathering, and the slope on either side of the arete steepened through mass wasting events and the erosion of exposed, unstable rock. The word ‘arête’ is actually French for edge or ridge; similar features in the Alps are described with the German equivalent term Grat.

Transverse valley

A transverse valley is a valley which cuts at right angles across a ridge or, in mountainous terrain a valley that generally runs at right angles to the line of the main mountain chain or crest. Its geomorphological counterpart is the longitudinal valley.

Water gap opening or notch which flowing water has carved through a mountain range

A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a practical route for road and rail transport to cross the mountain barrier.

Dominant rocks and mountain forms

The remains of an old mountain chain in the Laramie Mountains, Colorado Vedauwoo Rocks in winter.jpg
The remains of an old mountain chain in the Laramie Mountains, Colorado

Nappe or fold mountains, with their roughly parallel mountain chains, generally have a common geological age, but may consist of various types of rock. For example, in the Central Alps, granitic rocks, gneisses and metamorphic slate are found, while to the north and south, are the Limestone Alps. The Northern Limestone Alps are, in turn, followed by soft flysch mountains and the molasse zone.

The type of rock influences the appearance of the mountain ranges very markedly, because erosion leads to very different topography depending on the hardness of the rock and its petrological structure. In addition to height and climate, other factors are the layering of the rock, its gradient and aspect, the types of waterbody and the lines of dislocation. For hard rock massifs, rugged rock faces (e.g. in the Dolomites) and mighty scree slopes are typical. By contrast, flysch or slate forms gentler mountain shapes and kuppen or domed mountaintops, because the rock is not porous, but easily shaped.

See also

Related Research Articles

The Alps form part of a Cenozoic orogenic belt of mountain chains, called the Alpide belt, that stretches through southern Europe and Asia from the Atlantic all the way to the Himalayas. This belt of mountain chains was formed during the Alpine orogeny. A gap in these mountain chains in central Europe separates the Alps from the Carpathians to the east. Orogeny took place continuously and tectonic subsidence has produced the gaps in between.

Geology of the Appalachians

The geology of the Appalachians dates back to more than 480 million years ago. A look at rocks exposed in today's Appalachian Mountains reveals elongate belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ancient ocean floor – strong evidence that these rocks were deformed during plate collision. The birth of the Appalachian ranges marks the first of several mountain building plate collisions that culminated in the construction of the supercontinent Pangaea with the Appalachians and neighboring Little Atlas near the center. These mountain ranges likely once reached elevations similar to those of the Alps and the Rocky Mountains before they were eroded.

Alleghanian orogeny

The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 1957.

Flysch type of sedimentary rock

Flysch is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building episode. Examples are found near the North American Cordillera, the Alps, the Pyrenees and the Carpathians.

Moine Thrust Belt fault in Highland, Scotland, UK

The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast 190 kilometres (120 mi) south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of thrust faults that branch off the Moine Thrust itself. Topographically, the belt marks a change from rugged, terraced mountains with steep sides sculptured from weathered igneous, sedimentary and metamorphic rocks in the west to an extensive landscape of rolling hills over a metamorphic rock base to the east. Mountains within the belt display complexly folded and faulted layers and the width of the main part of the zone varies up to 10 kilometres (6.2 mi), although it is significantly wider on Skye.

Austroalpine nappes

The Austroalpine nappes are a geological nappe stack in the European Alps. The Alps contain three such stacks, of which the Austroalpine nappes are structurally on top of the other two. The name Austroalpine means Southern Alpine, because these nappes crop out mainly in the Eastern Alps.

Décollement

Décollement is a gliding plane between two rock masses, also known as a basal detachment fault. Décollements are a deformational structure, resulting in independent styles of deformation in the rocks above and below the fault. They are associated with both compressional settings and extensional settings.

Western Carpathians Mountain range along the border between Poland, the Czech Republic, and Slovakia

The Western Carpathians are a mountain range and geomorphological province that forms the western part of the Carpathian Mountains.

Allgäu Alps mountain range in the Northern Limestone Alps

The Allgäu Alps are a mountain range in the Northern Limestone Alps, located in Bavaria in Germany and Tyrol and Vorarlberg in Austria. The range lies directly east of Lake Constance.

Fatra-Tatra Area

The Fatra-Tatra Area or the Tatra-Fatra Belt of core mountains is a part of the Inner Western Carpathians, a subprovince of the Western Carpathians. Most of the area lies in Slovakia with small parts reaching into Austria and Poland. The highest summit of the whole Carpathians, the Gerlachovský štít at 2,655 m (8,711 ft), lies in the High Tatras range which belongs to this area.

Fold mountains Mountains formed by compressive crumpling of the layers of rock

Fold mountains are mountains that form mainly by the effects of folding on layers within the upper part of the Earth's crust. Before either plate tectonic theory developed, or the internal architecture of thrust belts became well understood, the term was used for most mountain belts, such as the Himalayas. The term is still fairly common in physical geography literature but has otherwise generally fallen out of use except as described below. The forces responsible for formation of fold mountains are called orogenic movements. The term orogenic has derived from a Greek word meaning mountain building. These forces act at tangent to the surface of the earth and are primarily a result of plate tectonics.

Geology of the Western Carpathians

The Western Carpathians are an arc-shaped mountain range, the northern branch of the Alpine-Himalayan fold and thrust system called the Alpide belt, which evolved during the Alpine orogeny. In particular, their pre-Cenozoic evolution is very similar to that of the Eastern Alps, and they constitute a transition between the Eastern Alps and the Eastern Carpathians.

Geology of the Pyrenees

The Pyrenees are a 430-kilometre-long, roughly east–west striking, intracontinental mountain chain that divide France, Spain, and Andorra. The belt has an extended, polycyclic geological evolution dating back to the Precambrian. The chain's present configuration is due to the collision between the microcontinent Iberia and the southwestern promontory of the European Plate. The two continents were approaching each other since the onset of the Upper Cretaceous (Albian/Cenomanian) about 100 million years ago and were consequently colliding during the Paleogene (Eocene/Oligocene) 55 to 25 million years ago. After its uplift, the chain experienced intense erosion and isostatic readjustments. A cross-section through the chain shows an asymmetric flower-like structure with steeper dips on the French side. The Pyrenees are not solely the result of compressional forces, but also show an important sinistral shearing.

Carpathian Flysch Belt Tectonic zone in the Carpathian Mountains

The Carpathian Flysch Belt is an arcuate tectonic zone included in the megastructural elevation of the Carpathians on the external periphery of the mountain chain. Geomorphologically it is a portion of Outer Carpathians. Geologically it is a thin-skinned thrust belt or accretionary wedge, formed by rootles nappes consisting of so-called flysch - alternating marine deposits of claystones, shales and sandstones which were detached from their substratum and moved tens of kilometers to the north (generally). The Flysch Belt is together with Neogene volcanic complexes only tectonic zone occurring along the whole Carpathian arc.

The main points that are discussed in the geology of Iran include the study of the geological and structural units or zones; stratigraphy; magmatism and igneous rocks; ophiolite series and ultramafic rocks; and orogenic events in Iran.

Geology of Germany

The geology of Germany is heavily influenced by several phases of orogeny in the Paleozoic and the Cenozoic, by sedimentation in shelf seas and epicontinental seas and on plains in the Permian and Mesozoic as well as by the Quaternary glaciations.

The geology of Slovakia is structurally complex, with a highly varied array of mountain ranges and belts largely formed during the Paleozoic through the Cenozoic.

Geology of Italy

The Geology of Italy includes mountain ranges such as the Alps, the Dolomites and the Apennines formed from the uplift of igneous and primarily marine sedimentary rocks all formed since the Paleozoic.. Some active volcanoes are located in Insular Italy.

References

  1. Whittow, John (1984). Dictionary of Physical Geography. London: Penguin, p 87. ISBN   0-14-051094-X.

Literature