From Wikipedia, the free encyclopedia Glarus thrust
Glarus thrust
Coordinates: 46°55′0″N 9°15′0″E / 46.916667°N 9.25°E /
46.916667; 9.25
World heritage
Swiss Tectonic Arena Sardona * Thrust faults of this kind are not uncommon in many
mountain chains around the world, but the Glarus thrust
UNESCO World Heritage Site is a well accessible example and has as such played an
important role in the development of geological knowl-
edge on mountain building. For this reason the area in
which the thrust is found was declared a geotope, a geo-
logic UNESCO world heritage site, under the name "Swiss
Tectonic Arena Sardona." The area of this "tectonic are-
na" encompasses 32,850 hectares of mainly mountainous
landscape in 19 communities between the 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 Swiss government made a first proposal
to declare the region world heritage to the International
Country Switzerland Union for Conservation of Nature (IUCN). The IUCN then
did not find the area to have an extraordinary or univer-
Type Natural
sal value and denied the proposal. The Swiss made a new,
Criteria viii this time successful proposal in March 2008. The region
was declared world heritage in July 2008, because "the
Reference 1179
area displays an exceptional example of mountain build-
Region ** Europe and North America ing through continental collision and features excellent
Inscription history
geological sections through tectonic thrust."[1]
The American Museum of Natural History in New
Inscription 2008 (32nd Session) York exposes a full-scale reconstruction of the Glarus
* Name as inscribed on World Heritage List thrust.[2]
** Region as classified by UNESCO
The Glarus thrust (German: Glarner Überschiebung) is a
major thrust fault in the Alps of eastern Switzerland.
Along the thrust the Helvetic nappes were thrusted 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 crops out over a relatively large
area in the cantons Glarus, St. Gallen and Graubünden,
due to its horizontal orientation and the high local relief.
Famous outcrops include those at Lochsite near Glarus
(the town) and in a mountain cliff called Tschingelhörner
between Elm and Flims (in the same cliff is a natural hole Drawing of the Glarus thrust in the Tschingelhörner by Hans
called the Martinsloch). Conrad Escher von der Linth, 1812.
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From Wikipedia, the free encyclopedia Glarus thrust
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 Switzer-
land in more detail. From that moment on, geologists be-
gan 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 plate tectonic theory in the 1950s an explana-
tion was found. In plate tectonics, the horizontal move-
ment of tectonic plates over the Earth’s soft asthenos-
phere causes horizontal forces within the crust. Present-
ly, geologists believe most mountain chains are formed
Glarus thrust fault at Piz Segnes
by convergent movements between tectonic plates.
History
The first naturalist to examine the Glarus thrust was
Hans Conrad Escher von der Linth (1767–1823). Escher
von der Linth discovered that, contradictory to Steno’s Glarus Thrust fault at Piz Segnes
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 References
at the ETH at Zürich, mapped the structure in more detail [1] Swiss Tectonic Arena Sardona - UNESCO World
and concluded that it could be a huge thrust. At the time, Heritage Centre
most geologists believed in the theory of geosynclines, [2] geopark association
which states that mountains are formed by vertical [3] Bertrand, M. (1884). "Rapports de structure des
movements within the Earth’s crust. Escher von der Alpes de Glaris et du bassin houiller du Nord".
Linth had therefore difficulty with explaining the size of 12:
Société Géologique de France Bulletin. 3rd 12 318–330.
the thrust fault. In 1848 he invited the British geologist [4] Geikie, A. (1883). "On the Supposed Pre-Cambrian
Roderick Murchison, an international authority, to come Rocks of St. David’s". Quarterly Journal of the
and look at the structure. Murchison was familiar with Geological Society 39 (1-4): 261–333. doi:10.1144/
larger thrust faults in Scotland and agreed with Eschers GSL.JGS.1883.039.01-04.21.
interpretation. However, Escher himself felt insecure [5] Schardt, H. (1893). "Sur l’origine des Préalpes
about his idea and when he published his observations romandes". Eclogae geologicae Helvetiae 4: 129–142.
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. Literature
Eschers successor as professor at Zürich, Albert Heim • Franks, Sibylle; Rudolf Trümpy (September 2005).
(1849–1937), initially stuck to his predecessors interpre- "The Sixth International Geological Congress: Zürich,
tation of two anticlines. However, some geologists 1894" (PDF). Journal of International Geoscience.
favoured the idea of a thrust. One of them was Marcel Episodes (International Union of Geological sciences)
Alexandre Bertrand (1847–1907), who interpreted the 28 (3): 187–192. http://www.episodes.org/
structure as a thrust in 1884, after reading Heims obser- backissues/283/187-Franks.pdf. Retrieved
vations.[3] Bertrand was familiar with the Faille du Mi- 2008-07-10.
di, a large thrust fault in the Belgian Ardennes. Mean-
while, British geologists began to recognize the nature of
thrust faults in the Scottish Highlands. In 1883, Archibald
External Links
Geikie accepted that the Highlands are a thrust system.[4]
Swiss geologists Hans Schardt and Maurice Lugeon then
discovered in 1893 that in western Switzerland, Jurassic
rock layers are on top of younger molasse too, and ar-
gued that the structure of the Alps is a large stack of
nappes, large sheets of rock that had been thrusted on
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From Wikipedia, the free encyclopedia Glarus thrust
Categories:
• World Heritage Sites in Switzerland
• Geology of the Alps
• Flims
• Visitor attractions in Switzerland
• Glarus thrust
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