Etsch glacier
The Etsch Glacier , also known as the Rhaetian Glacier or Rhaetian Glacier in Italian parlance , was an Ice Age glacier in the Alps , the main stream of which flowed through the Adige Valley . During the last ice age, the Würm Ice Age , the Etsch Glacier formed the largest glacier system on the south side of the Alps with a length of about 350 kilometers.
The origin of the Etsch Glacier could be reconstructed on the basis of typical rock debris from its moraines in the eastern Rhaetian Alps (hence the second name). The Etsch Glacier was temporarily connected to the Inn Glacier on the Reschen Pass via a transfluence . In the Vinschgau valley , further glaciers from the side valleys of the Ötztal Alps and the Ortler Alps merged with the Etsch Glacier . The largest inflowing glaciers were the Eisack glacier and the Rienz glacier coming from the Pustertal . The pressure exerted by these led to an increase in the ice masses and thus caused the enormous thickness of the Adige Glacier.
The minimum height of the glaciation, reconstructed on the basis of glaciers and moraine litter, was around 2600 meters on Piz Lad near the Reschen Pass at the height of the glaciation around 20,000 years ago, in Vinschgau at 2400 meters, at Bozen still at 2000 meters and at Trento at around 1800 Meters. An ice thickness of around 1500 meters can be derived from this. Between the Dolomites and the Ortler group there was an ice surface 40 kilometers wide, without being interrupted by a rocky island.
The glacier divided above Trento :
- Its orographically right branch (more powerful towards the glacier's peak ) flowed over a low saddle to Terlago and reached the Sarca valley via Vezzano , where it merged with the Sarca glacier, excavated the basin of today's Lake Garda (an important glacier edge lake ) and raised remarkable terminal moraines (e.g. in Solferino , Custoza and Lonato del Garda ). Since the Sarca carries relatively little water and thus sediment loads, it has only been able to fill the relatively small area between Arco and Riva since the end of the Würm Ice Age around 12,000 years ago .
- The left branch, on the other hand, which flowed further south in the Adige Valley, was dammed back because of the narrow valley there and did not reach the foreland south of Rivoli even when the glacier was at its peak . A lake at the edge of the glacier that probably existed here for a short time was quickly backfilled by the Adige, which was heavily loaded with sediment.
The only ice masses in the area of today's South Tyrol that did not flow over the Adige Glacier came from the eastern Dolomites, where parts of the ice flowed off to the Piave Glacier .
Individual evidence
- ↑ a b c d Volkmar Singl, Volkmar Mair : Introduction to the geology of South Tyrol . Weise, Bozen 2005, p. 70 f .
- ↑ Garda Classico: The Natural History of Lake Garda
- ↑ Headquarters for teaching media on the Internet e. V. (ZUM): Lake Garda as an example of the interpretation of an "origin model" - note: the orographic right branch is called the "Rhaetian Glacier" here, the left "Etsch Glacier"