Scribbling

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A scratch , better known as glacier scrapes , is a typical surface structure of the rock caused by glacial abrasion.

Scratched debris from the Münsterländer gravel sand train in Neuenkirchen / Offlum
Glacier scrapes on a rock in the Baltic Sea, northern Sweden
Glacial scars on Kelleys Island, Ohio
Close up of the ground surface with scratches that run almost horizontally. Many stress cracks can be seen vertically.

Glaciers are not standing ice masses, rather they represent a viscous mass with an extremely slow flow movement. The glacier moves away from the origin of the ice (glaciated mountain regions or Scandinavian inland ice during the Ice Age). Stones that, depending on the shape of the terrain, are picked up and carried along at the bottom or on the sides of the glacier, “scratch” the surrounding rock . The direction of movement of the ice at that time can be seen from the scratches or grooves.

This geological peculiarity is often found on the southern Scandinavian coasts and also in the northern Alpine foothills (e.g. at Fischbach near Flintsbach am Inn , where the Inn glacier was located during the Würm Ice Age ).

Occasional glacier scrapes can also be found on ice age debris in northern Germany. On small stones there is sometimes an almost mirror-smooth surface. In these cases, no rubble was embedded in the ice, the grinding was done by embedded sand or by glacial flour, which is created by the mutual grinding of debris and the subsoil. Attachments that have been scratched several times are rare. The so-called ice canters , in which at least two grinding surfaces touch each other, are very rare .

Web links

Commons : Glacial striation  - album with pictures, videos and audio files

Individual evidence

  1. ↑ Glacier scrapes . In: Spectrum Lexicon of Geosciences. Retrieved December 12, 2017 .
  2. ↑ Jürgen Ehlers : The Ice Age . Spektrum Akademischer Verlag, Heidelberg 2011, ISBN 978-3-8274-2326-9 , box "Gletscherschrammen", p. 72 .