Glarus thrust

Coordinates: 46°55′N 9°15′E / 46.917°N 9.250°E / 46.917; 9.250
Source: Wikipedia, the free encyclopedia.
Glarus Overthrust
Sardona
CriteriaNatural: (viii)
Reference1179
Inscription2008 (32nd Session)
Websitewww.glarusoverthrust.org
Coordinates46°55′N 9°15′E / 46.917°N 9.250°E / 46.917; 9.250
Glarus thrust is located in Switzerland
Glarus thrust
Martinsloch

The Glarus thrust (German: Glarner Überschiebung) is a major thrust fault in the Alps of eastern Switzerland. Along the thrust the Helvetic nappes were thrust more than 100 km to the north over the external Aarmassif and Infrahelvetic complex. The thrust forms the contact between older (Helvetic) Permo-Triassic rock layers of the Verrucano group and younger (external) Jurassic and Cretaceous limestones and Paleogene flysch and molasse.

The Glarus thrust

Martinsloch
).

World Heritage

Thrust faults of this kind are not uncommon in many mountain chains around the world, but the Glarus thrust is a well accessible example and has as such played an important role in the development of

Surselva, Linthtal and Walensee. In the arena are a number of peaks higher than 3000 meters, such as Surenstock (its Romansh name is Piz Sardona, from which the name comes), Ringelspitz and Pizol
.

In 2006 the

tectonic thrust."[1]

The American Museum of Natural History in New York exposes a full-scale reconstruction of the Glarus thrust.[2]

Drawing of the Glarus thrust in the Tschingelhörner by Hans Conrad Escher von der Linth, 1812.
Glarus thrust fault at Piz Segnes

History

The first

Steno's law of superposition, older rocks are on top of younger ones in certain outcrops in Glarus. His son Arnold Escher von der Linth (1807–1872), the first professor in geology at the ETH at Zürich, mapped the structure in more detail and concluded that it could be a huge thrust. At the time, most geologists believed in the theory of geosynclines, which states that mountains are formed by vertical movements within the Earth's crust. Escher von der Linth had therefore difficulty with explaining the size of the thrust fault. In 1848 he invited the British geologist Roderick Murchison, an international authority, to come and look at the structure. Murchison was familiar with larger thrust faults in Scotland and agreed with Escher's interpretation. However, Escher himself felt insecure about his idea and when he published his observations in 1866 he instead interpreted the Glarus thrust as two large overturned narrow anticlines
. This hypothesis was rather absurd, as he admitted himself in private.

Escher's successor as professor at Zürich,

stack of nappes, large sheets of rock that had been thrust on top of each other.[5]
At the turn of the century, Heim was also convinced of the new theory. He and other Swiss geologists now started mapping the nappes of Switzerland in more detail. From that moment on, geologists began recognizing large thrusts in many mountain chains around the world.

However, it was still not understood where the huge forces that moved the nappes came from. Only with the arrival of

tectonic plates over the Earth's soft asthenosphere
causes horizontal forces within the crust. Presently, geologists believe most mountain chains are formed by convergent movements between tectonic plates.

Glarus Thrust fault at Piz Segnes

Notes and references

  1. ^ Swiss Tectonic Arena Sardona – UNESCO World Heritage Centre
  2. ^ geopark association Archived 2011-07-26 at the Wayback Machine
  3. ^ Bertrand, M. (1884). "Rapports de structure des Alpes de Glaris et du bassin houiller du Nord". Société Géologique de France Bulletin. 3rd. 12: 318–330.
  4. doi:10.1144/GSL.JGS.1883.039.01-04.21
    .
  5. ^ Schardt, H. (1893). "Sur l'origine des Préalpes romandes". Eclogae geologicae Helvetiae. 4: 129–142.

Literature

External links

Wikimedia Commons has media related to Glarus thrust.
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