Diffluence

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Diffluence of the Theodul Glacier above Zermatt , which branches southwest of the Klein Matterhorn (left) into the Lower Theodul Glacier (center) and the Upper Theodul Glacier (right).

Diffluenz (from Latin dif , 'apart', + fluere , 'flow') is a term from glaciology and describes the division of a glacier into several branches. The term was established at the beginning of the 20th century by Albrecht Penck when he was investigating the shape-forming influences of Ice Age glaciers in the Alps. Even today, the term is used almost exclusively in the geomorphological context, especially when examining the development processes of valleys . Diffluence occurs when a glacier that fills a fluvially shaped valley overflows over the valley slopes into a neighboring valley.

In the area of ​​a former diffluence, after the glacier has melted, terrain steps, so-called diffluence steps, can occur . On the one hand, the valley slope of the main valley to the opening of the hanging side valley of the branching off smaller branch is called this. On the other hand, the term stands for a terrain step opposite the general slope of the valley in the main valley below the branch point. The latter could develop because at this point the glacial erosion decreases due to the reduced ice pressure and the slower flow velocity.

An example of a diffluence during the Würme Ice Age occurred at the Rhine Glacier near Sargans in eastern Switzerland. Part of the glacier coming from the south did not flow in a northerly direction through the Rhine valley, but in a north-westerly direction through the Seeztal and the Walensee valley.

Sometimes a distinction is made between diffluence and transfluence . The latter expression is used when the crossing does not take place via the lateral slopes of the valley, but already at the point of origin and thus the glacier ice crosses a main watershed into another valley system.

Individual evidence

  1. ↑ Map section with Theodul Glacier at geo.admin.ch
  2. ^ Hans Murawski, Wilhelm Meyer: Geological dictionary. 12th edition, Spektrum Akademischer Verlag, Heidelberg 2010, ISBN 978-3-8274-1810-4 , p. 31 ( online ).
  3. ^ Albrecht Penck: Glacial features in the surface of the Alps. In: Journal of Geology. Volume 13, pp. 1-19, 1905 ( online ).
  4. ^ A b David Leslie Linton: The Forms of Glacial Erosion. In: Transactions and Papers (Institute of British Geographers). No. 33, 1963, pp. 1-28 ( abstract ).
  5. ↑ Diffluenz at Spektrum.de
  6. ↑ Eduard Gerber: The longitudinal profile of the Alpine valleys. In: Geographica Helvetica. Volume 11, 1956, pp. 160-215 ( online )
  7. ↑ René Hantke: On the diffluence of the worm ice age Rhine glacier near Sargans and the late glacial glacier stands in the Walensee valley and in the Rhine valley. In: Quarterly publication of the Natural Science Society Zurich. Volume 115, pp. 101-126 ( online ).