An ''urstromtal'' (plural: ''Urstromtäler'') is a type of broad glacial

valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ov ...

, for example, in northern

Central Europe Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the ar ...

, that appeared during the

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

s, or individual

glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

s of an ice age, at the edge of the Scandinavian

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at L ...

and was formed by meltwaters that flowed more or less parallel to the ice margin. ''Urstromtäler'' are an element of the

glacial series The glacial series refers to a particular sequence of landforms in Central Europe that were formed during the Pleistocene glaciation beneath the ice sheets, along their margins and on their forelands during each glacial advance.

Emergence and structure

Important for the emergence of the ''Urstromtäler'' is the fact that the general lie of the land on the

North German Plain The North German Plain or Northern Lowland (german: Norddeutsches Tiefland) is one of the major geographical regions of Germany. It is the German part of the North European Plain. The region is bounded by the coasts of the North Sea and the Bal ...

and in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

slopes down from south to north. Thus the ice sheet that advanced from Scandinavia flowed into a rising terrain. The meltwaters could therefore only flow for a short distance southwards over the sandurs (outwash plains) before having to find a way to the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian ...

basin that was parallel to the ice margin. At that time, the area that is now the North Sea was dry as a result of the low level of the sea. As elements of the glacial series, ''Urstromtäler'' are intermeshed with sandur areas for long stretches along their northern perimeters. It was over these outwash plains that the meltwaters poured into them. ''Urstromtäler'' are relatively uniformly composed of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of ...

s and

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

s; the grain size can vary considerably, however. Fine sand dominates especially in the upper sections of the ''Urstromtal'' sediments. The thickness of the ''Urstromtal'' sediments also varies a great deal, but is mostly well over ten metres. ''Urstromtäler'' have wide and very flat valley bottoms that are between 1.5 and 20 kilometres wide. The valley sides, by contrast are only a few to a few dozen metres high. The bottom and the edges of an ''Urstromtal'' may have been significantly altered by more recent processes, especially the thawing of dead ice blocks or the accumulation of

sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

s. In the post-glacial period, many ''Urstromtäler'' became bogs due to their low lying situation and the high water table.

''Urstromtäler'' in Central Europe

In Central Europe there are several ''Urstromtäler'' from various periods. * Breslau-Magdeburg-Bremen ''Urstromtal''; (

, Germany); formed during the Saale glaciation * Glogau-Baruth ''Urstromtal''; (Poland, Germany); formed during the

Weichselian The Weichselian glaciation was the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet (the Fenno-Scandian ice sheet ...

* Warsaw-Berlin ''Urstromtal''; (Poland, Germany); formed during the Weichselian * Thorn-Eberswalde ''Urstromtal''; (Poland, Germany); formed during the Weichselian * The term Elbe ''Urstromtal'' refers to the Elbe valley roughly at the height of

Genthin Genthin () is a town in Jerichower Land district, in Saxony-Anhalt, Germany. Geography Genthin is situated east of the Elbe river on the Elbe-Havel Canal, approx. northeast of Magdeburg and west of Brandenburg. The municipal area consists ...

to the Elbe estuary at

Cuxhaven Cuxhaven (; ) is an independent town and seat of the Cuxhaven district, in Lower Saxony, Germany. The town includes the northernmost point of Lower Saxony. It is situated on the shore of the North Sea at the mouth of the Elbe River. Cuxhaven has ...

. The meltwaters of the three above-mentioned Weichselian ''Urstromtäler'' flowed successively through this valley towards the North Sea basin. * The term Rhine ''Urstromtal'' for the

Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , sour ...

valley from

Düsseldorf Düsseldorf ( , , ; often in English sources; Low Franconian and Ripuarian language, Ripuarian: ''Düsseldörp'' ; archaic nl, Dusseldorp ) is the capital city of North Rhine-Westphalia, the most populous state of Germany. It is the second- ...

to its mouth on the North Sea is disputed. The Rhine was certainly a route for meltwaters during the Saale glaciation. The structure of the valley is however clearly older and was formed by recent

tectonics Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

. * In the Alpine glaciation zone of Central Europe the term ''Urstromtal'' is not used. In this region, the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , pa ...

and, periodically, the

carried the meltwaters away. Some sections of the aforementioned main valleys have been given their own names. The Lusatian ''Urstromtal'' and the Aller ''Urstromtal'' are parts of the Breslau-Magdeburg-Bremen ''Urstromtal''. The Baruth, Berlin and Eberswalde ''Urstromtäler'' are common short names for the associated sections of the ''Urstromtal'' in

Brandenburg Brandenburg (; nds, Brannenborg; dsb, Bramborska ) is a state in the northeast of Germany bordering the states of Mecklenburg-Vorpommern, Lower Saxony, Saxony-Anhalt, and Saxony, as well as the country of Poland. With an area of 29,480 square ...

. In addition to the large main valleys there are also numerous smaller meltwater valleys (''Urstromtalungen''). Their appearance is similar to that of the great ''Urstromtäler'', but they are considerably shorter. They are also not linked to a sandur and a

terminal moraine A terminal moraine, also called end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge ...

. ''Urstromtäler'' of Central Europe (Poland, Germany and Denmark especially) were directly connected to the North Atlantic Ocean, via the

Channel River The Channel River was a prehistoric river flowing between England and France during periods of low sea level during the ice ages. Its tributaries included the river Rhine in modern-day Netherlands, the River Thames in modern-day England and other r ...

, during Pleistocene maximum glaciations, i.e. at times of confluence of the British and Fennoscandian ice-sheets in the intervening North Sea.

Features

''Urstromtäler'' should not be confused with

tunnel valley A tunnel valley is a U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. They can be as l ...

s. The latter are formed beneath, not in front of, the ice mass. In addition most tunnel valleys run from north to south. The principal direction of ''Urstromtäler'' is from east to west. Today ''Urstromtäler'' are only partly used by rivers, because the majority have found shorter routes to the sea (like the

Oder The Oder ( , ; Czech, Lower Sorbian and ; ) is a river in Central Europe. It is Poland's second-longest river in total length and third-longest within its borders after the Vistula and Warta. The Oder rises in the Czech Republic and flows th ...

and

Vistula The Vistula (; pl, Wisła, ) is the longest river in Poland and the ninth-longest river in Europe, at in length. The drainage basin, reaching into three other nations, covers , of which is in Poland. The Vistula rises at Barania Góra in t ...

). The straight troughs of the ''Urstromtäler'' between the rivers were used for canal routes due to their low gradient, for example for the Elbe–Havel Canal or the Oder–Havel Canal. Because the land in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the C ...

and on the

Russian Plain The East European Plain (also called the Russian Plain, "Extending from eastern Poland through the entire European Russia to the Ural Mountaina, the ''East European Plain'' encompasses all of the Baltic states and Belarus, nearly all of Ukraine, a ...

tilts towards the south, the formation of ''Urstromtäler'' there during the ice age did not take place. The

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, ...

and its tributaries carried the meltwaters of the North American ice sheet away. In Eastern Europe the meltwaters flowed down the river basins of the

Dnieper } The Dnieper () or Dnipro (); , ; . is one of the major transboundary rivers of Europe, rising in the Valdai Hills near Smolensk, Russia, before flowing through Belarus and Ukraine to the Black Sea. It is the longest river of Ukraine an ...

Don Don, don or DON and variants may refer to: Places *County Donegal, Ireland, Chapman code DON *Don (river), a river in European Russia * Don River (disambiguation), several other rivers with the name * Don, Benin, a town in Benin * Don, Dang, a v ...

and

Volga The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchm ...

. ''Urstromtäler'', whether sandy or boggy, posed considerable obstacles to movement in the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

. As a result, the

trade routes A trade route is a logistical network identified as a series of pathways and stoppages used for the commercial transport of cargo. The term can also be used to refer to trade over bodies of water. Allowing goods to reach distant markets, a sin ...

converged on points where the valley could be crossed comparatively easily. These hubs thus became favourite sites for the founding of towns or castles. Examples from the German state of Brandenburg include Berlin,

Fürstenwalde Fürstenwalde/Spree (; Lower Sorbian: ''Pśibor pśi Sprjewje'') is the most populous town in the Oder-Spree District of Brandenburg, Germany. Geography The town is situated in the glacial valley ('' Urstromtal'') of the Spree river north of the ...

Luckenwalde Luckenwalde (; Upper and dsb, Łukowc) is the capital of the Teltow-Fläming district in the German state of Brandenburg. It is situated on the Nuthe river north of the Fläming Heath, at the eastern rim of the Nuthe-Nieplitz Nature Park, a ...

and

Baruth/Mark Baruth/Mark is a town in the Teltow-Fläming district of Brandenburg, Germany. It is situated 24 km east of Luckenwalde, and 53 km south of Berlin. Geography Baruth/Mark is structured in the following parts of town,Main constitution ...

, and from Lower Saxony the town of Vorsfelde and Wolfsburg Castle.

References

Literature

* H. Liedtke: ''Die nordischen Vereisungen in Mitteleuropa''. 2nd ed., Trier 1981, , 307 p. * H. Liedtke, J. Marcinek (ed.): ''Physische Geographie Germanys''. 3rd ed., Gotha 2002, , 786 p. * Johannes H. Schroeder (ed.): ''Führer zur Geologie von Berlin und Brandenburg, No. 2, Bad Freienwalde – Parsteiner See''. 2nd improved edition. Geowissenschaftler in Berlin und Brandenburg e. V., Selbstverlag, Berlin 1994, , * Johannes H. Schroeder (ed.): ''Führer zur Geologie von Berlin und Brandenburg, No. 5, Nordwestlicher Barnim – Eberswalder Urstromtal''. Geowissenschaftler in Berlin und Brandenburg e. V., Selbstverlag, Berlin 2004, , * Johannes H. Schroeder (ed.): ''Führer zur Geologie von Berlin und Brandenburg, No. 9, Oderbruch – Märkische Schweiz – Östlicher Barnim''. Geowissenschaftler in Berlin und Brandenburg e. V., Selbstverlag, Berlin 2003, , {{Authority control Glaciology

''Urstromtäler'' in Central Europe

Features

See also

References

Literature