Glacial series

The glacial deposits (Latin glacies " ice " ) called in Central Europe, trained in a specific order landforms that are formed during the Pleistocene glaciations through each glacial advance under the glaciers, at the edge positions and their foreland.

Definition

The term glacial deposits in 1882 was first coined by Albrecht Penck for the northern Alpine foreland. Later the term was expanded and extended to the Scandinavian glaciation area.

Components of the ideal, full glacial series are:

• A ground moraine with a tongue basin
• A Endmoränenkette, the arc- shape around the tongue basin
• A gravel field or outwash plain in front of the Endmoränenkette
• A glacial valley in which abflossen meltwater of glaciers

It borders the arranged with the term glacial series by geomorphological rules and formed by the glacier forms on the geological characteristics after the glaciers associated with glacial sediments. A full glacial series arises when the ice edge (not the ice ) remains stable over time and is not destroyed again and again by the further advance of glacial ice.

Glacial deposits in the foothills

The Alpine glaciers, who trained a Eisstromnetz during the highlights of the ice ages, repeatedly exceeded the border of the Alps and pushed forward into the foothills of the Alps. There they were from geographically extensive foreland glaciers. Penck differed in this alpine Vorlandvergletscherung the landforms of the tongue basin with the ground moraine, the terminal moraine and the ballast box in front of it.

The trough- shaped basin, which resulted from the Ausschürfen the ground by the glacial ice are called tongue basin, as was once the glacier tongue here. In these basins form, if no drainage is possible in a glacier retreat, the so-called glacial lakes edge or tongue Beck reservoirs, such as a number of lakes in the Salzkammergut. Typical forms within the tongue basins in the Alpine foothills are drumlins. Glacial troughs are rare. To the tongue basins lie at the edge of the ice deposited, referred to as the terminal moraine ridges of glacial till.

Glacial till is also the substance of reason, side, and not always present, medial. The ground moraine is the material that was once transported under and in the glacier and has been deposited in terms of area in the former glacier bed. The lateral moraine refers to the material which deposits on the edge of a glacier. A lateral moraine, which is no longer actively fed by a glacier with material because this has withdrawn from climatic reasons is called a lateral moraine. In the Alps are often found lateral moraines, which were formed in the Little Ice Age, there are several meters higher than the present glacier surface and extend down too far before the current glacier tongue. Medial arise from lateral moraines in the union of two glaciers.

Beyond the Moränenzone is the gravel plain, which was filled by the melt waters of the ice. They got their water mostly from glacier gates, their former location on the dips Endmoränenzüge be seen even today. Often the gravel surfaces are significantly terraced; younger outflows have cut so-called Trompetentälchen in the older gravel surfaces. The material of the gravel plains can be seen from the glacial till. The transport capacity of the melt water is much lower than that of the glacier, so that larger stones can not be carried out of the tongue basin. Components with smaller grain size as clay and sand can be transported very much, so they are hardly to be found in the gravel plains.

Glacial valleys caused by eisrandparalleles drainage of melt water. Generated by the meltwater subglacial stream as in northern Germany do not occur in the Alpine foothills, its function was taken over by the existing large rivers Danube, Rhine, Rhone and Po or its tributaries, which deliver the melt water of the glaciers.

Glacial deposits in northern Central Europe

The northern part of Central Europe was repeatedly reached or passed over by the Scandinavian ice sheet. The forms of glacial series therefore follow in the northern central Europe from north to south on each other:

The ground moraine consists mostly of flat to undulating flat areas where the ice was deposited the boulder clay. Tongue basin in which the Ausschürfen of material played a significant role come before only subordinate and are in the Scandinavian glaciation area a part of the ground moraine. Since the advancing end of the ice, the existing landscape completely buried among themselves, the glacial forms and deposits in northern Germany are widely disseminated. Glacial grooves, however, are in the northern central Europe a widespread phenomenon.

The Endmoränenzüge limit the moraine to the south. The moraines are often trained patchy and not as high as in the Alpine foothills, but occur in the low mountain ranges in relief landscape as much in appearance. Due to the incompleteness of the neutral term ice stage has prevailed for the Endmoränenzüge in Northern Germany.

More or less extensive Sander adjoin the terminal moraines. You are alluvial fan formed by meltwater. Even their water they received from glacier gates that cut the Endmoränenzüge.

The meltwater that abflossen on the outwash plains, gathered in the glacial valley and flowed parallel to the ice margin mostly to the northwest from. Glacial valleys are a special form for the northern central Europe.

Glacial deposits as a model of landscape development

Like all models are also the model of the glacial series the real conditions only simplifies again. In particular, is often overlooked, that the shapes of glacial series almost simultaneously formed side by side during the ice margin remains at the terminal moraine. Furthermore, the ice must once advance to the later moraines and on the other hand also melt again. The processes which occur in the process of the model of the glacial series change significantly. A common variation is for example spillage of ground moraine by younger meltwater.

In addition, repeated advance of the glaciers for interleaving different forms of the old glacial series lead. So, for example, dehydrated closely consecutive Endmoränenzüge in Brandenburg on the same outwash plains and the same glacial valley.