Marsh

As march (country) ( v. niederdt. , Altsächs. Mersc ), also known as mash, Mersch or alluvium, is defined as the Holocene area of ​​north-west German coasts and rivers, and similar landforms around the world.

Landscape

Marshes are generally flat land with no natural elevations. They are located roughly at sea level inland of Watts and the salt marshes and extend to the Geest, the Pleistocene origin. Development History they are among the youngest geological formations: You are Holocene in origin, having a beautiful post.

Extensive marshes in Germany there are not only directly on the North Sea, but also for example as a river marshes in tidal zone of influence of the tidal rivers, particularly the Elbe, Weser, Eider, Oste and Ems. The marshland of the German North Sea coast, together with the subsequent on the Dutch and Danish side faces the largest marshland world. The longitudinal extent of the marshes between Den Helder (NL) and Esbjerg ( DK ) is roughly 550 km. Although even further inland lowland landscapes are located often colloquially referred to as " march " (or variations thereof, such as Leinemasch in Hanover with the Maschsee ) pedological and hydrological it has absolutely precise to floodplains.

• Seemarschen
• Transitional and brackish marshes
• River Marsh
• Organo - and peat marshes
• Jung march and Altmarsch

Formation

Output of all marshes is the watt. The marshes caused by the gradual silting up of the salt marshes by sedimentation of pioneer plants. This natural process was used by the coastal people in the past for land reclamation. The sedimentation rate is at its highest when the marshes are not yet grown too high above the sea level. When storm and spring tides the salt marshes flood, the carried material falls out at the end of the surf zone, as the transport force becomes smaller due to the reduced velocity of the waves.

So a slightly elevated zone is formed directly on the coast or on the river bank; the so-called highlands of mine geneous sediments. Inland, there will be no sedimentation, which is why here the deeper Sietland arises. The slow rise in sea level, the height difference between the highlands and Sietland grows and can be several meters. The surface can drop to below the level of the Tiede low water and has to be continuously drained. In Sietland leaking groundwater and precipitation can develop extensive fens, which are liable to subsidence in drainage through from the Geest.

For land reclamation and flood protection, the marshes were diked earlier ( no longer practiced ). These protected by river and sea dikes areas are recognized as polder ( in Schleswig -Holstein), Groden ( in Lower Saxony) or polder ( in the Netherlands) referred. Where no protection is provided by dikes, for example, holms, farmsteads and settlements because of the risk of flooding to several meters high are piled mounds or mounds ( Dutch: terpene ) built.

The marshland is kept dry by a drainage system consisting of ditches, bettors or Wedderungen, pumping stations and sluices. Without this constant drainage, the march would be an uninhabitable marshland. By draining the land is ( partially below sea level ) bagged. The lowest land point in Germany is 3.54 meters below sea level and is located on the outskirts of New Village Sachsenbande in Wilstermarsch west of Itzehoe in Schleswig -Holstein.

Marsh soils

The marshes form according to the German Soil Mapping the class M in the Department of the semi-terrestrial soils ( groundwater soils ). The German soil classification is one of the few world rankings, appeals to them as a separate class. Most systems - such as the WRB - see in them only parts of other classes. This feature may be due to the fact that marshes in north-west Germany occupy a large area.

All marsh soils have as Gleye on the leveling A / Go / Gr. To distinguish gley march are but above three features, all of which must be met:

• Regional assignment in the marshes
• Starting material are littoral sediments of the brackish water zone (starting point watts). These are very schluffreich (rarely even pure silt is present), are due to battered shells very rich in lime and usually have the entire sediment body to the Pleistocene reason a high percentage of organic matter on. Typical of littoral sediments are numerous very fine layers, which are due to storm surges.
• Young bottom of the Holocene.

Immediately after the deposition of the sediments is a soil formation. Thus, from the Wadden a march, then the surface must be above the average but tidal range.

The seven distinct soil types in Germany the marsh soils form a logical, chronological order starting with the Watts. The stages of the young marshes are getting through. The Altmarschen one of the four possible types is achieved.

• Rohmarsch ( just created, salt meadow)
• Kalkmarsch ( diked today; maximum of 300 years)
• Klei march (about 300 to 600 years)

From about 1000 years ago. In Germany, more than 2500 years.

• Dwogmarsch
• Kink march
• Detention wet march
• Organomarsch

Subtypes, or other common designations, which represent not have its own soil type, are bog marsh and Geest march. It also transitions between young marshes and Altmarschen are possible, which are activated as subtypes of the more pronounced soil type.

In the Wadden occur under anaerobic conditions, large amounts of iron sulfide ( FeS ). This is coloring the ground intensely black and is also in the young marshes currently. Grow out the sediments from the daily flood area, it comes to aeration of the soil and the beginning of the sulfide oxidation. In this chemical reaction, sulfuric acid is released and the black iron sulfide is converted to brownish FeOOH, which is why the ground color changes rapidly. This process continues until all of the iron sulphide is oxidized. Thus the entering in all soils Kalkauswaschung is greatly accelerated in young marshes, because the sulfuric acid destroys the primary sedimented carbonates.

Alongside, a further processes such as sagging and Aussüßung in soil development. Later in the beginning very salt- rich soils of Rohmarsch be desalted, that is, magnesium and especially sodium ions are washed out. Due to the increasing ventilation could also intensify the oxidative processes, resulting in the degradation of organic matter and structure formation. These processes lead to the formation of Kalkmarschen and finally after decalcification for clothes march.

Use

The marshes of northwest Germany are almost completely in use. Here, depending on the soil type is either grassland or arable predominant (see also the different soil types of the marshes ). The marshes of the young march are very fruitful in the rule. In addition to the livestock they are also used for farming. So Dithmar is primarily known for the cabbage. The Old Country is one of the largest fruit growing in Central Europe, the Vierlande and Marschlande in Hamburg are among the most important growing areas for vegetables and flowers. Due to the problematic drainage, however, is on the Sietland mostly grassland management ( meadow, pasture ) to find.

The fertility of the marshes is based on several factors: the clay soils are heavy and fine-grained due to solids and nutrient- rich. Due to the coastal location, the climate is more balanced than in the interior, especially frosts are rare. Of particular importance for the microclimate are the numerous drainage ditches that provide both protection from frost in spring as well as from strong heat in summer. In addition, the marsh soils have a high water table, so that the water supply of plants is far better than on the Geest.

The fertile soils are a major reason for distinct cultural and historical developments in the marshes, for example, for the long period of independence of Dithmar. In many cases, the marsh dwellers confined to the 20th century by the poorer inhabitants of the Geest from, for example, in the politics of marriage. It was considered improper to marry a resident of the Geest, partly it came to the disinheritance or for violation of the family or the village.