Alpentor
In geology, the Alpine gate is the breakthrough of an entire glacier (ice flow) from the Alps into the Alpine foothills during the Ice Age .
Alpine gates in the Würm Ice Age
In particular, where in the Würme Ice Age several glaciers from different valleys met or where narrow areas flowed through at the edge of the Alps, the ice accumulated, so that such narrow areas had a significant influence on the further rise in the ice level. In this way, they led to lower passes and mountain ridges being overflown by ice and the glaciers uniting to form a network of ice streams .
Alpine gates, at which particularly large amounts of ice poured into the surrounding plains, were primarily located at the mouths of large longitudinal valleys such as the Inn , Rhine or Salzach valleys . These glacier tongues penetrated up to 50 kilometers into the plains. But even nowadays rather insignificant valleys such as Isar , Loisach and Ammertal could produce large tongues of ice when their glaciers were nourished by larger ones such as the Inntal glacier ( e.g. via the Fernpass ). In contrast, with such large glaciers, largely isolated valleys such as the Iller or Lech valleys were able to produce much smaller glacier tongues.
Another prerequisite for glaciation reaching into the foothills of the Alps are high mountains. East of the Salzach Valley, the glacier tongues barely reached the edge of the Alps, as mountains such as the Niedere Tauern , unlike the Hohe Tauern, could not produce enough ice. Therefore, alpine gates were mainly to be found in the Bavarian Alpine foothills. One of the few examples on the southern edge of the Alps was the comparatively small Alpine gate of today's Tagliamento valley .
Example Inntal Glacier
In the Inntal (towards Rosenheim ) the Inntal glacier squeezed between the Wildbarren and the Kranzhorn at an altitude of approx. 1300 m above sea level. NN through. A tributary, the Isartal Glacier, flowed south of Bad Tölz between the Blomberg and the Rechelkopf at an altitude of approx. 1000 m in the lowlands.
At the Walchen- and Kochelsee a branch of the Inntal Glacier ran at an altitude of 1400 m over the Kesselberg between the Jochberg and the Herzogstand .
The Loisach Glacier, another tributary, flowed through between the Wank and the Kramerspitz near Garmisch at an altitude of approx. 1700 m . In today's Murnau , the ice flow reached up to approx. 1200 m .
Individual evidence
- ↑ Dirk van Husen: The Eastern Alps in the Ice Ages (= from the geological history of Austria ). Federal Geological Institute, Vienna 1987, ISBN 3-900312-58-3 .
- ↑ Rolf KF Meyer, Hermann Schmidt-Kaler : In the footsteps of the Ice Age south of Munich - eastern part (= walks in the history of the earth . Volume 8 ). 2nd Edition. Pfeil, Munich 2002, ISBN 3-931516-09-1 .