Esker

An Os ( Wallenberg or Esker ) is a bahndamm similar embankment of layered melt -water sands and gravels, which was formed during the ice under the glacier ice. Oser are a part of the ground moraine.

Formation

Oser caused by subglacial meltwater. The ice contains as any glacier moraine also ( fine clay to coarse blocks). The melt streams on the ice who are looking for more or less short- track their way to the glacier base ( water has a higher density than ice) take on the moraine and store it along its subglacial ( under the glacier ) run again. Therefore Oser are glazifluviale forms. They usually consist of coarse sand, gravel and boulders. As the meltwater flowing parallel to Eisbewegungsrichtung, run Oszüge in Northern Germany usually from north to south. Often, they are neighborhood or even within a glacial trough. The creation or maintenance of Oser is connected to the standstill or the melting of the ice sheet during the ice ages.

Form

Oser rise like irregularly shaped embankments in the landscape, as they were surrounded left and right by ice. You reach in Northern Germany rarely more than 20 m in height, but can be several tens of kilometers long.

Due to the glacier continues to flow from the surface of the water, the water is often below the ice under high pressure and can therefore also flow upwards. This explains the highly variable amount of eskers and the breaks in the Oszügen, which are the rule rather than the exception.

Oser and drumlins

Oser see at first glance the drumlins similar, but have a different genesis. They may therefore not be confused. Drumlins formed during the active flow of the glacier under the ice and therefore show a streamlined shape.