V-shaped valley

V-shaped valleys ( called because of their frequent simplified symmetric valley slopes and V - valleys ) are valleys which are located primarily in medium-and high mountains. Often they are so narrow that they can be considered narrow valley at its sole. The genesis same notched sole valleys are, however, associated with the sole valleys. V-shaped valleys occur with strongly predominant vertical erosion and denudation of simultaneously occurring on the valley slopes.

• 2.1 valley bottom
• 2.2 suspension

• 3.1 Basics
• 3.2 Wind Systems
• 3.3 Precipitation

• 4.1 Geobotany
• 4.2 phytogeography
• 4.3 Geozoologie

• 5.1 settlement
• 5.2 management
• 5.3 transport
• 5.4 Geomorphological overmolding
• 5.5 Biogeographical overmolding

Geomorphology

Precursor

The especially in headwaters of rivers due to large disparities strongly flowing water, partly in the form of waterfalls, erosive cuts into the rock and leads to the formation of a ravine. Depending on the nature of the rock it follows a V-shaped valley or gorge ( canyon). These are mainly found in the high mountains. The depth of erosion is so strong that a weathering of slopes and their removal can not follow. The rock walls of the ravines are thus nearly perpendicular and only as wide as its riverbed. The maximum depth of a gorge is determined by the critical height of the cliffs.

Formation

When the critical height of the cliffs is exceeded, due to the instability rockfalls and landslides. The slopes are shifted back and flatten the vertical valley sides. This has an intense lateral erosion of slopes result.

Did the valley now mostly a V-shape, so it is called a V-shaped valley. A distinction is still in ideal-typical symmetric and asymmetric V-shaped valleys, which is mainly made ​​out of the homogeneous slope of the valley slopes. The shift back is characterized by a strong material removal on the slopes, which can withstand the deep erosion of the river. The flatter the valley slopes are, the more discontinuous acts denudation. If there is initially in a deep gorge still regularly rockfalls, lateral erosion occurs later only with appropriate meteorological events. This Denudationen shall then be monitored by slip or glide as well as in the form of debris flows and other Fließungen.

Notched sole valleys are characterized by a smaller depth of erosion and a small but real side erosion. Some of these can mark sections of a Kerbtals due to impenetrable layers in the geological structure of the rock. A special form of V-shaped valleys are the canyons. The transition from the V-shaped valley to Sohlental is fluid. Erosion on the slopes, the water is forced to move the removed material. Is the slope of the valley low, the water begins to meander. At the undercut slope it is true then often on the side of the valley and picks up this intensely. How strong is the effect against the slope at those points can be observed at high water. Deposits of material occur simultaneously in the slip, which widens the sole of the valley.

In its form V-shaped valleys can the rift valleys of large rivers the same, but penetrate in contrast to these not the attacked Mountains. Therefore they are steeper in its entire length.

Successor

V-shaped valleys are not the last valley shape that can form in the erosion of mountains. In high mountains with glaciers shaped valleys lead the expanding ice ages when glaciers. This leads to intense lateral glacial erosion, while the vertical erosion almost completely ceases. The ice grinds the valley walls further on ( Deterministic Sion) and blasts rock material by the enormous pressure partially out. This happens especially in the narrowest part of the valley, shortly above the bottom, as there is the equilibrium pressure of the glacier at its highest. At the edge of the glacier further material is entrained and Detraktion itself erosive effect. The resulting valley forms are shaped valleys and fjords ( U-shaped valleys ).

The notched mountains is completely eroded with time and leveled it; the difference in elevation between valley floor and mountain peaks decreases again. In the ever flattening the mountains anyway wide Kerbsohlental becomes a Sohlental. The reason for the reduction of the level difference between the valley floor and mountains must not be due to erosion. It can also be caused by plate tectonics or Schollentektonik. In particular, plaice, it is possible that they sink and so even the V-shaped valley continues sedimented waters, so filling. If there is an enormous lowering of the soil, the rivers developed in the shallow valley to a steppe. Later, the V-shaped valley is completely leveled in a sedimentary basin.

Soil Science

Valley floor

The soils in a V-shaped valley are strongly marked by the deposition and erosion of the flowing body of water. Is it possible to assign almost all soils large trough valleys still in the sole area the alluvial soils, that is more severe in V-shaped valleys. The floor in the V-shaped valley is quite different structures by sedimentation. In shallower passages as well as in the slip it comes to deposits, which can be very humus and lößhaltig depending on the procurement of the mountain. In Kerbsohlental in which the sole is wider and thus at high water much more normal dry surfaces to sediment exist, are already pronounced and comprehensive alluvial soils.

Especially in Kerbsohlental are the old arms of the watercourse. The soils are marked by the dirt and gravel of the ancient bed and can evolve over time to Auengleyen. On the other hand, these patterns of an old riverbed are also marked in floods caused by flood with flow and erosion.

The type of soil on slopes is generally strongly influenced by rocks, some large areas interrupted by rocks. Interestingly, to occur on the flanks slope in the course and also in the cross section of a valley within a few hundred yards wide variety of soils. Depending on the type of soil on the slope resulting from various factors, especially the orientation in the wind system ( registration of loess and dust ) and the slope of the hill include (thickness of erosion and vegetation density ). Where the slope is torn over a large area due to erosion, especially the virgin soils of Syroseme occur. They consist of massive gravel and loose rock layers with low humus horizon mighty.

In the temperate climate zones formed on the upper slopes along the valley brown soils. Strong from the bedrock of the mountains dependent, these are usually Kalkbraunerden. Compared to brown soils on level ground, these are still very flat.

Climate and Weather

In V-shaped valleys, there is another local climate than the surrounding mountains. The reason for this is of course the lower position, but also the other irradiation by the sun. This causes various phenomena.

Basics

Depending on the direction of a valley of sunshine in the valley is very different. Valleys, pointing to the north and south are, tend to be disadvantaged because in the morning and evening hours, a shadow is cast by the valley slopes. Valleys, which run in an east-west direction, thus illuminated longer if their northern slope is not too steep. It also plays a role, therefore, on which latitude the valley lies.

A climatic determination of the Valley takes place - of course in addition to the prevailing macro climate - even by the location in the mountains. For the micro-climate is crucial if the valley is located on the windward or leeward side.

Wind systems

The valley is dominated by two wind systems that are interrelated and used in their creation. On the valley walls it comes to the slope wind circulation and in the valley floor to valley wind itself. Together, these form the mountain - valley wind system. Cause of wind is always a pressure difference between air masses of two areas. With V-shaped valleys, this pressure difference is caused by the varying intensity radiation from the sun.

Since this engräumige wind effect requires intense sunlight, it is mainly observed in summer at high pressure weather conditions. But even in winter can lead to sub-processes of the phenomenon due to the almost exclusive irradiation of the mountains. However, the effect is also overlaid by the winds of weather situations.

The slope wind circulation occurs when the upper valley slopes in the morning are heated by intense sunshine. The warm air rises there and draws air from the valley to. Since a few meters is still cool air over the slope, the slope wind does not rise straight up on, but remains roughly on a slope, so as wind felt. The cold air above it drops out and moves to compensate back to the valley. The slow but steady upswing is used for example when paragliding.

In the afternoon the up-draft is on a slope transverse to the direction of the valley almost completely, since now the bottom is heated and returns in the evening and during the night hours to completely, falling into the cold air on the mountain side. At the bottom but the night is sometimes emitted through heat, which is why it is there for the vertical ascent of the air.

The valley wind blowing in direction of the valley follows the vertical directions of the slope wind time lag. In the morning it blows down the valley, bringing in the cool air of the high altitudes in the foothills of the valley. Its direction is not determined by the temperature differences between the bottom and upper slope but by the pressure difference between the foothills and the altitude at the top of Kerbtals. But cause of the valley wind are mainly Ungleichnisse the slope wind circulation. Around noon hours around are no longer sufficient, the falling air masses, to compensate for the rising slope: It comes out to a wind from the foothills of the valley, blowing up the valley. In the mid- night hours again fall larger air masses into the valley, as the center yet started to rise, causing the sloping wind is formed in the valley floor that lasts until sunrise.

The lowest temperatures in the valley are therefore reached just before sunrise ( in the valley). The wind system will also impact on the local formation of precipitation.

Precipitation

In the type of precipitation formation shaped valleys are dominated by specific fog phenomena. The fog is thereby substantially affected by the wind system of valleys. Called the Valley fog fog caused by the low temperatures in the lowland valley terrain. As the temperature is lowest through the air mass balance in the last hours of the night, only then, nebulae and talk until the wee hours of the day. Fog itself is no precipitation, but consists mainly on the vegetation of the slopes as dew from.

The local rainfall is influenced not only by the orientation of the valley and the valley wind. Suppresses back that flows into the valley of humid air masses, thus increasing the amount of precipitation. The updraft carries rain areas out of the valley and so reduces the amount of precipitation.

Biogeography

Geobotany

Due to the geological, hydrological, meteorological but also small scale of the cross- sectional shape of the Kerbtals is also formed in the vegetation engräumig a different plant community. The ideal type of companies can also penetrate Just because of the small space available and can not be so clearly anywhere diffuse.

The bottom of a Kerbtals is naturally covered by riparian forests, which are divided into only a few meters wide softwood forest close to the waters and the Hartholzaue especially in the temperate latitudes. Can actually spread a lowland forest but because of the higher places on offer water level almost exclusively in notched sole valleys. Depending on the gradient of the valley but there is also the softwood entirely absent, since it is destroyed by regular floods with Eisversatz and sediment effect in the spring. At such points, shallow waters slopes are populated only by shallow shrubs and perennials such as Vorwaldgehölzen.

The character of the valley sides of a Kerbtals is still intermittent and very different shape so often especially in the lower part of the slope typical ravine forests that have the extreme slope and Gesteinshaltigkeit adjusted, the shape of the settlement. Ravine forests belong to Central Europe to the book mixed forests and also tolerate the soil type of hardwood alluvial forest in the valley bottom, so that especially towards waters penetrate both forest types at the transition. Often the gorge-like character of a valley side through the cut bank of the water body is formed which extends into the slope until immediately. At these points there is no riparian forest, the ravine forest reaches there until closer to the waters, and often over it.

In the higher or flatter slopes are formed as a natural habitat more mixed beech forests. Essential for the formation of specific forest communities of the Book ( in Central Europe) are mainly the predominant soil types. Due to the rocky subsoil of possible brown earth soils, especially dry - slope limestone beech occur in the V-shaped valleys. At appropriate southern slopes oak dry forests form. In dry air the slopes of Kerbtals offer particularly unfavorable conditions compared to the sole, as there is then no groundwater available. Exposed slope south-facing slopes are then often freely colonized by vegetation or small sclerophylls is reflected especially if through stony ground heat and light.

The occurring in the V-shaped valleys in the northern hemisphere most common tree species are among the beech and birch plants. In general it can be stated also that trees in the valley bottoms rather shallow roots, on the flanks, however, are rather deep roots. In the ravine forests even occur frequently only those species that can be handed over taproots sufficient support.

The rivers have a high flow rate, making the river beds are covered with coarse gravel and stones. With these serious conditions grow in the waters of V-shaped valleys hardly aquatic plants. Especially protected locations in stone columns, but also tree trunks or roots type plants in the flowing waters hold, and thus any possibility for sedimentation of fine material.

In some places the water can be dammed or slowed down to pond or swamp -like interruptions in natural notched sole valleys. At these points are obtained by sedimentation in the water and on the banks particularly good conditions for vegetation. Due to the deep valley and the surrounding forest vegetation are higher in such places no tall grasses, which are common in lowland to lowland.

Phytogeography

The interaction between plants and spatial form of the Kerbtals primarily affects the geomorphic process of material transfer. Plants take up on the slopes to water and thus ensure a natural retention. This leads immediately to the fact that the soil on the slope is protected from erosion. By flattening the peak discharge of the water in the valley is indirectly protected the soil from erosion of the valley floor through the vegetation on the slope and supports the sedimentation.

Loose -surface-area material of the slopes, especially leaves and branches is, however, very easily removed and deposited on the valley floor. In particular, water- organic material is thus shifted from the slope to the valley floor. This explains why the slope often thin humus layer despite vegetation.

Because despite vegetation comes in V-shaped valley to denudation of the valley sides, the river carries fluviatile sediments. In addition to geomorphological factors especially the waters near vegetation to sedimentation helps by slowing the obstacle as flooded waters.

Geozoologie

The V-shaped valley also offers wildlife engräumig different habitats, the combined use of many types and between which such a strong relationship. The south-facing slopes with stony surface spread mainly provide cold-blooded animals shelter, warmth and light. The ravine forest is so especially for reptiles and amphibians, a habitat with better living conditions than a flat and dense forest. Many species also need the high temperature differences on a slope, prevailing at a between day and night and on the other between exposed and shaded places.

The northern exposed slope with much cooler living conditions and is not nearly as dry. These conditions are more ideal for nocturnal animals homoiotherme. In stony ground also this slope cut into rock crevices, caves and overhangs, providing hiding places.

The cooler and low-light bottom is not far lighter and warmer valley slopes, but in comparison to the side of the valley that spreads more humid habitat. For insects and amphibians, the wet room plays an important role in the propagation of larvae. Because they need most fish are low in or free water for their larvae, they played the high dynamics of the watercourse to the emergence of small-scale Gewässeraltarmen. The character of concrete V-shaped valleys as habitat depends therefore also on how rich in water is the river.

The river offers all sufficiently warm biomes an abundance of fish. The habitat of mountain is usually directly connected to other waters such as large rivers and eventually the sea. As a very oxygen-rich waters it is even some marine fish from reproducing. The reason for the oxygen abundance is the steep valley shape of Kerbtals and the associated movement and turbulence of the water.

Human Geography

V-shaped valleys provide for the people as a place to live and economies, as well as for infrastructure development benefits such as protection from wind and sun. They also form - apart from exceptions in the subtropics - a fresh water supply. Problems they prepare the people by floods that cause the formation of the valleys, essentially, but threaten the people in the form of flash floods.

Colonization

In contrast to the gorge or steep rift valleys, the V-shaped valley is habitable by adapted forms of colonization for humans. Because of their narrowness colonization is possible in the form of villages and towns almost exclusively in the valley floor. In such valleys were therefore forms the series village. Be limited human settlements in V-shaped valleys next to the historical and political divisions very clearly by natural events ( narrow and steep passages). In the system of settlements is to be noted that in a V-shaped valley is always the danger of floods. This can especially in the curves of the body of water, forming very strong impact and Gleithänge in the V-shaped valley, strong shifts of the shore waters cause, and thus endanger the settlements.

Especially at places where short side valleys resulted in a larger V-shaped valley and allowed a lateral ascent over the ridge or at least high levels, is developed villages in V-shaped valleys to cities. Roads, streets and modern transport connections are led by V-shaped valleys. Important places developed here where developed in valleys crossing points. This is, for example, at larger branches of a valley of the case, but also possible where side valleys provide a convenient crossing of the valley.

Small and medium-sized cities could well develop in V-shaped valleys, but offers a V-shaped valley in the strict sense is not enough space for large cities, but is (which then lie in adjacent basin-like valleys ) in the expansion of the cities taken. Examples of such large cities in Germany that could penetrate through incorporation and growth in V-shaped valleys are Freiburg at about 1000 meters altitude difference in the urban area and in some parts even Dresden, Wiesbaden and Würzburg.

A special form of urban settlement is a Kerbtals Wuppertal, which is located in Kerbsohlental the Wupper and was able to develop and expand in this. In places the bottom has been extended beck -like, partially populated the valley is only about 300 meters wide. The lateral side valleys are part of the traffic engineering and development are reshaped urban usually.

In the Alps, where large-scale colonization exclusively in the valleys is possible to major cities developed in the hollows of which were inferred from V-shaped valleys urban. Innsbruck is an example of the colonization of a glaciated valley out.

Management

V-shaped valleys can manage in a variety of ways:

Steep V-shaped valleys have at their flanks mostly to forestry. The hard part is the removal of the harvested timber. The slope forest is deducible not everywhere by forest roads, so that sooner skidding horses were used. As the development has not improved (especially on skid tracks ) for large technical equipment such as forwarders, the use of draft horses (apart from organic farms ) is hardly economically. That's why more and more forests are no longer used on the valley slopes for timber. Forestry in the V-shaped valley means in particular conservation today.

Agricultural often offer through the waters fertile soils. Basically, V-shaped valleys can use agriculturally in the valley in every way that allows the air in the valley. However, a V-shaped valley in its sunshine duration and thus the growing season (see flora and fauna) limited by the steep slope. Besides the pure width of the valley floor and the water and its old river beds limit the usable land in the valley. A high proportion of the valley floor can therefore be characterized by difficulty of arable gravel and gravel layers.

Narrow valleys in Europe are currently used primarily on the valley floor through pasture and meadow economy. Especially when keeping livestock on pastures they offer over plateaus advantage of the water supply. Only at wider points they can to agriculture in small plots.

The beneficiary in the sunlight slope can be in temperate latitudes often the fruit and partially also use for viticulture. Fruit growing is often operated in the higher ridge lines in the form of orchards, which allow a more efficient utilization of soil.

Another use of the valley takes place for water management. In the present, this is limited almost exclusively to the operation of reservoirs whose dams complete V-shaped valleys to narrow and thus damming the rivers of the valley. The purpose of the reservoirs can be seen in the power generation and flood control. The fast-flowing waters of the Kerbtals is however used for energy for many centuries. The original technology is the waterwheel with the mills were operated. Since the V-shaped valley is steeper, thus it has a higher density of potential and kinetic energy of the water. This is a list of water mills with favorable " overshot waterwheel " possible. The slope of the water of the valley (or a forked course ) is to artificially reduce the kinetic energy to be selectively act on the waterwheel.

The largest spread in Central Europe had the water mills in the Frühindustrialierung. In the time next to cereals and raw materials of glass and color production as well as spices and coffee were ground. Water was used for the production of paper and wood boards. By water-powered sawmills in the valleys had the particular advantage that they are very close to the wood mining area, the forests were on the mountain side (see above). Particular importance due to the proximity to the mining area had also held hydroelectric power for grinding ore in the V-shaped valleys.

In mining, V-shaped valleys often form the access to mines that are driven vertically through a tunnel into the mountain. In such places, they also need to provide enough space for the outsourcing of lined material adjacent the respective slopes. A special form of this tunnel is the " water drainage gallery ", drained the mines. The V-shaped valley is used as the exit point of the tunnel having to dewatering. When creating large areas with appropriate depth, such a tunnel must have a partly considerable length to a sufficiently deep V-shaped valley. The Rothschönberger Stolln in the Ore Mountains is more than 50 miles long, crosses under the insufficiently deep valley of the Freiberger Mulde and therefore drains into the V-shaped valley of Triebisch.

Transport

V-shaped valleys are the starting point of passports that lead through the mountains. For V-shaped valley as a useful transport mainly contribute the protective roles of the valley. Both the man and transport animals are better protected in the valley from the wind and sun. Were transported mainly as goods still very much with animals, played the distributed and secure water supply in the valley a major role. Thus, V-shaped valleys have been in subtropical regions often the only alternative for traffic routes, where their waters consistently led water.

The role of Kerbtals as promoters of infrastructure increased again with the construction of the railroad in the 19th century. The low pitch capability of the first railways were decisive factor to create routes in the valleys. At the upper end of such a passage was provided by a voltage applied to the ramp slope, the rise in the higher elevations of the mountain. In high mountain tunnel and passes lead from a V-shaped valley to another. Depending on the height of the tunnels is called base tunnel when it crosses the mountain at its "base" or from the summit tunnel, if only done a climb ramps. Is the V-shaped valley is too steep or the area on a slope is not sufficient for a ramp, circle spiral tunnels have been used to the valley to gain height in a spiral ascent "next ". A well-known example of this is on the Wutachtalbahn in the Black Forest.

The biggest problem of roads in V-shaped valleys are strong flood. Especially railroad tracks that existed long wooden sleepers were bloated and washed out. The sub- structures of roads and rail systems are also prone to erosion to total annihilation. Distance railway lines of which are threatened to the present day.

With the construction of high-speed lines, the role of Kerbtals has changed for the railroad. With more powerful engines of the trains but also through cost-effective tunnel and bridge modes of the V-shaped valley is become more of an obstacle. Newly built railway lines are similar in course of construction of highways. In the German low mountain ranges highways are almost since the beginning created so that they cross the V-shaped valleys to run straight. Since highways remained may have stronger gradients in them is the curve with direct transitions from bridges to tunnels in the central mountain region rather rare. With many new lines this design but is applied over long distances.

Urtypisch for the course of modern railway lines is 1869 finished Sachsen- Franken- Magistrale, which runs on the flat panel of the Ore Mountains from east to west. The route crosses a lot of V-shaped valleys of the Ore Mountains on large buildings, to which the Göltzschtalbrücke or Hetzdorfer Viaduct (1992 decommissioned) belong. The course of this railway line was rather because due to the parallel course to Erzgebirgskamm achieving high speeds.

Geomorphological overmolding

The use of the V-shaped valleys by humans has not gone without a trace in numerous places. To improve the usability of the man changed the shapes of valleys partly considerably. The most pronounced changes evoke dams that contribute to a to an artificial sedimentation, on the other valley slopes erode much more homogeneous than a river.

Man has also attacked even targeted the valley slopes. In mountains with particularly usable or precious stones like sandstone, basalt, granite or marble he reached most likely to Talflanken by quarries the rock strata. In tunnels outputs of the man in the vicinity tried - so in the valley - deposit mined rock. He thus contributed in some places artificially to sediment at. Once a mining area had reached a certain size, has begun to transport material already in the mine upwards, as the deposition space is very limited in the valley.

In the construction of wider roads, the valley slopes were attacked. Especially railway lines have limited turn radius and thus forced to widen the valley floor. In order to broaden the valley, valley slopes were blown open, and so original V-shaped valleys in ravines or valleys notched sole turns in some places. The resulted ledges must be secured after the bursting particularly against erosion and rockfall. Alternatively, tunnels are built, running parallel to the valley and are not intended to leave the valley.

Ultimately, the man also has an effect on its water control on the form-building processes in the valley. Artificially secured bank, especially when they are defined by fixed walls that prevent a uniform denudation in the valley. Usually breaking a valley slope at those points where a curve is sufficient water directly to the slope, away evenly. Due to security measures of the people it comes in such places only during floods to significant erosion on slopes. Purpose of the protection is in addition to the protection of residential buildings, especially the protection of transport routes in the valley.

Biogeographic overmolding

In the agricultural development of the Kerbtals especially the habitats of the valley floor were changed in notched sole valleys by the activities of man. The extensive riparian forests (see above) were cleared there in favor of pasture and forage meadows. In many places the man also eliminated local and small -scale wetlands in order to manage them better. Depending on the deepening of the water body and associated depth of groundwater form in the valley fen meadows or wet meadows. Both habitats are dependent on the management, otherwise they would quickly overgrown by tall herbaceous corridor and later recaptured by forests.

On the slopes of forests were displaced in favor of the orchards and especially on the south side in favor of viticulture.

The interrupted by hedges pastures are now considered worth protecting cultural landscape, as they are very rich in species, especially if they are supplemented by permanently flooded meadow parts and natural hedges and embankments.