Urstromtal

Glacial valleys are broad lowlands in northern Central Europe, which were formed in the Ice Age, or in the various stages of an ice age on the edge of the Scandinavian ice sheet and are caused by the more or less eisrandparallele drainage of melt water. They belong to the Glacial series.

Structure and Formation

It is important in the formation of glacial valleys that the general slope of the landscape in the northern German lowlands and in Poland was directed from south to north. So this coming from Scandinavia ice pushed against a rising terrain ahead. The meltwater could therefore flow only a short distance to the Sandern south and then looked for a way parallel to the edge of the ice in the North Sea basin. The territory of the North Sea at that time was due to the significantly lower sea dry terrain.

As part of the glacial series, glacial valleys dovetail at its northern edge over long distances with outwash plains over which the melting glacial valley water was supplied. Glacial valleys are of relatively uniform of sands and gravels; the grain size can also vary greatly. Especially in the upper portions of the Urstromtalsedimente dominate fine sands. The thickness of the Urstromtalsedimente also highly variable but is usually far more than ten meters.

Glacial valleys have a broad, flat valley bottom table, which is between 1.5 and 20 km wide. The valley slopes, however, are only a few to a few tens of meters high. The sole or the edges of a glacial valley may be customized extensively by younger, in particular through the Austauen of dead ice blocks or Aufwehen of dunes. In the post-Pleistocene glacial valleys are many vermoort due to their deep location and the high ground water level associated with it.

Glacial valleys in Central Europe

In Central Europe, there are several glacial valleys from different periods.

• Breslau -Magdeburg - Bremen glacial valley; (Poland, Germany ); originated in the Saale ice age
• Glogau - Baruth glacial valley; (Poland, Germany ); originated in the Weichseleiszeit
• Warsaw-Berlin glacial valley; (Poland, Germany ); originated in the Weichseleiszeit
• Thorn- Eberswalde glacial valley; (Poland, Germany ); originated in the Weichseleiszeit
• As same - glacial valley of the Elbe Valley is known approximately from the height of Genthin to the Elbe estuary at Cuxhaven. The meltwater of the three mentioned Weichselian glacial valleys flowed successively through the valley towards the North Sea basin.
• Controversial is the name Rheinurstromtal for the Rhine Valley from Dusseldorf to its mouth in the North Sea. Although the Rhine served there as drainage of meltwater during the Saale ice age. However, the unit of the valley is much older and fueled by young tectonics.
• In alpine glaciation in Central Europe one does not speak of glacial valleys. The Danube and the Rhine partly led there from the meltwater.

Sections of said main valleys have given their own names to some extent. The Lusatian glacial valley and the all- glacial valley are sections of the Breslau -Magdeburg - Bremen glacial valley. Baruth, Berlin and Eberswalde glacial valley are common abbreviations for the respective Urstromtalabschnitte in Brandenburg.

In addition to the large main valleys are numerous smaller Urstromtalungen. Its appearance is similar to the first large glacial valleys. However, they are considerably shorter. Also, the reference to a sander and a terminal moraine is missing.

Special features of glacial valleys

Glacial valleys should not be confused with the glacial troughs ( subglacial ). The latter arise under and not in front of the ice. In addition, most glacial troughs extend from north to south. The main direction of the glacial valleys is directed from east to west. Glacial valleys are now used only in sections of rivers, as most of today a shorter route back to reach the sea (such as the Oder and Vistula ). The line-like lowering of the glacial valleys between the rivers were used because of their low gradient for the pipe laying, for example for the Elbe- Havel Canal and the Oder- Havel Canal.

Since the slope of the landscape is addressed in North America and on the Russian platform to the south, it was there during the ice age not to the formation of glacial valleys. The Mississippi River and its tributaries have discharged meltwater of the North American ice sheet. In Eastern Europe the meltwater of the river basins of the Dnieper, Don and Volga flowed from.

Glacial valleys, whether sandy or vermoort, set in the Middle Ages considerable traffic obstructions dar. Therefore, the trade routes bundled in tight spaces where you could cross the valley comparatively comfortable. The constrictions were therefore a preferred location for city foundations and castles. Examples of Brandenburg Berlin, Fiirstenwalde, Luckenwalde and Baruth / Mark, and from Lower Saxony Vorsfelde and the Wolfsburg Castle.