The Glarus thrust () is a major

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...

in the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

of eastern

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. Along the thrust the

Helvetic nappes The Helvetic nappes ({{langx, de, Helvetische Decken) are a series of nappes in the Northern part of the Alps and part of the Helvetic zone. They consist of Mesozoic limestones, shales and marls that were originally deposited on the southern cont ...

were thrust more than 100 km to the north over the external Aarmassif and

Infrahelvetic complex The Infrahelvetic complex is a tectonic unit in the Swiss Alps. It consists of autochthonous rocks of the former southern continental margin of the European Plate. The Infrahelvetic complex has been overthrusted by the Helvetic nappes, that part ...

. The thrust forms the contact between older (Helvetic) Permo-

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

rock layers of the Verrucano group and younger (external)

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s and

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

flysch Flysch () is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building ep ...

and

molasse __NOTOC__ In geology, "molasse" () are sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse deposits accumulate in a foreland basin, especially on top of flys ...

. The Glarus thrust crops out over a relatively large area in the

cantons A canton is a type of administrative division of a country. In general, cantons are relatively small in terms of area and population when compared with other administrative divisions such as counties, departments, or provinces. Internationally, th ...

relief Relief is a sculpture, sculptural method in which the sculpted pieces remain attached to a solid background of the same material. The term ''wikt:relief, relief'' is from the Latin verb , to raise (). To create a sculpture in relief is to give ...

. Famous outcrops include those at Lochsite near

Glarus Glarus (; ; ; ; ) is the capital of the canton of Glarus in Switzerland. Since 1 January 2011, the municipality of Glarus incorporates the former municipalities of Ennenda, Netstal and Riedern.Tschingelhörner The Tschingelhörner (also spelled ''Tschingelhoren'') are a chain of mountain peaks in the Glarus Alps, located on the border between the Swiss cantons of Canton of Glarus, Glarus and Graubünden. They are composed of several summits on a long ...

'' between

Elm Elms are deciduous and semi-deciduous trees comprising the genus ''Ulmus'' in the family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical- montane regions of North America and Eurasia, ...

and

Flims Flims () is a municipality in the Imboden Region in the Swiss canton of Graubünden. The town of Flims is dominated by the Flimserstein which one can see from almost anywhere in the area. Flims consists of the village of Flims (called Flims D ...

(in the same cliff is a natural hole called the 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

geological Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...

knowledge on

mountain building Mountain formation occurs due to a variety of geological processes associated with large-scale movements of the Earth's crust (List of tectonic plates, tectonic plates). Fold (geology), Folding, Fault (geology), faulting, Volcano, volcanic acti ...

. For this reason the area in which the thrust is found was declared a

geotope A geotope is the geological component of the abiotic matrix present in an ecotope. Example geotopes might be an exposed outcrop of rocks, an erratic boulder, a grotto or ravine, a cave, an old stone wall marking a property boundary, and so forth. ...

, a geologic

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

, under the name "Swiss Tectonic Arena Sardona." The area of this "tectonic arena" encompasses 32,850

hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), that is, square metres (), and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. ...

s of mainly mountainous landscape in 19 communities between the

Surselva Surselva Region is one of the eleven administrative districts in the canton of Graubünden in Switzerland. It was created on 1 January 2017 as part of a reorganization of the canton.Linth The Linth (pronounced "lint") is a Switzerland, Swiss river that rises near the Linthal, Glarus, village of Linthal in the mountains of the cantons of Switzerland, canton of canton of Glarus, Glarus, and eventually flows into the Obersee (Züri ...

tal and

Walensee Lake Walen, also known as Lake Walenstadt or (), is one of the larger lakes in Switzerland. Located in the east of the country, about two thirds of its area are in the canton of St. Gallen and about one third in the canton of Glarus. Its na ...

. 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 Swiss most commonly refers to: * the adjectival form of Switzerland * Swiss people Swiss may also refer to: Places * Swiss, Missouri * Swiss, North Carolina * Swiss, West Virginia * Swiss, Wisconsin Other uses * Swiss Café, an old café located ...

government made a first proposal to declare the region World Heritage to the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN). The IUCN then did not find the area to have an extraordinary or universal value and denied the proposal. The Swiss made a new, this time successful proposal in March 2008. The region was declared a World Heritage Site in July 2008, because "the area displays an exceptional example of mountain building through continental collision and features excellent geological sections through

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

thrust." The

American Museum of Natural History The American Museum of Natural History (AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. Located in Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 21 interconn ...

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

exposes a full-scale reconstruction of the Glarus thrust. Escher Martinsloch

History

The first

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

to examine the Glarus thrust was

Hans Conrad Escher von der Linth Hans Conrad Escher von der Linth (born 24 August 1767 in Zürich; died 9 March 1823) was a Swiss scientist, artist, and politician. He headed the "Great Council of Switzerland" in 1798, a period of French occupation. He also published a survey o ...

(1767–1823). Escher von der Linth discovered that, contradictory to Steno's

law of superposition The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the ...

, older rocks are on top of younger ones in certain

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...

s 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 Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

. At the time, most geologists still accepted the theory of

geosyncline A geosyncline (originally called a geosynclinal) is an obsolete geology, geological concept to explain orogeny, orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged.#Sengor1982, ...

s, 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 Sir Roderick Impey Murchison, 1st Baronet (19 February 1792 – 22 October 1871) was a Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigating and desc ...

, 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

anticline In structural geology, an anticline is a type of Fold (geology), fold that is an arch-like shape and has its oldest Bed (geology), beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex curve, c ...

s. This hypothesis was rather absurd, as he admitted himself in private. Escher's successor as professor at Zürich,

Albert Heim Albert Heim (12 April 184931 August 1937) was a Swiss geologist, noted for his three-volume ''Geologie der Schweiz''. Born in Zürich, he was educated at Zürich and Berlin universities. Very early in life he became interested in the physical fe ...

(1849–1937), initially stuck to his predecessor's interpretation of two anticlines. However, some geologists favoured the idea of a thrust. One of them was

Marcel Alexandre Bertrand Marcel Alexandre Bertrand (2 July 1847 – 13 February 1907) was a French geologist born in Paris. He was the son of mathematician Joseph Louis François Bertrand (1822–1900), and son-in-law to physicist Éleuthère Mascart (1837-1908). He st ...

(1847–1907), who interpreted the structure as a thrust in 1884, after reading Heims observations. Bertrand was familiar with the Faille du Midi (

Variscan orogeny The Variscan orogeny, or Hercynian orogeny, was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. Nomenclature The name ''Varis ...

), a large thrust fault in the Belgian

Ardennes The Ardennes ( ; ; ; ; ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Belgium and Luxembourg, extending into Germany and France. Geological ...

. Meanwhile, British geologists began to recognize the nature of thrust faults in the

Scottish Highlands The Highlands (; , ) is a historical region of Scotland. Culturally, the Highlands and the Scottish Lowlands, Lowlands diverged from the Late Middle Ages into the modern period, when Scots language, Lowland Scots language replaced Scottish Gae ...

. In 1883,

Archibald Geikie Sir Archibald Geikie (28 December 1835 – November 1924) was a Scottish geologist and writer. Early life Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. ...

accepted that the Highlands are a thrust system. Swiss geologists

Hans Schardt Hans Schardt (18 June 1858 – 3 February 1931) was a Swiss geologist and a professor at the University of Neuchâtel and at the ETH and the University of Zurich. He contributed to studies on the folding and movement of layers of the earth based ...

and

Maurice Lugeon Maurice Lugeon FRS(For) HFRSE FGS (10 July 1870 – 23 October 1953) was a Swiss geologist, and the pioneer of nappe tectonics. He was a pupil of Eugène Renevier. Named for Maurice Lugeon, the lugeon is a measure of transmissivity in rocks ...

then discovered in 1893 that in western Switzerland, Jurassic rock layers are on top of younger molasse too, and argued that the structure of the Alps is a large

stack Stack may refer to: Places * Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group * Blue Stack Mountains, in Co. Donegal, Ireland People * Stack (surname) (including a list of people ...

nappe In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the ...

s, large sheets of rock that had been thrust on top of each other. 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

force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

s that moved the

s came from. Only with the arrival of

plate tectonic theory Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

in the 1950s an explanation was found. In plate tectonics, the horizontal movement of

tectonic plates Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

over the Earth's soft

asthenosphere The asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between c. below the surface, and extends as deep as . However, the lower boundary of the asthenosphere i ...

causes horizontal forces within the crust. Presently, geologists explain the formation of most

mountain chain A mountain chain is a row of high mountain summits, a linear sequence of interconnected or related mountains,Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, p 87. . or a contiguous ridge of mountains within a larger mo ...

s by the

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

evolving between

accompanied by a

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

process in which the heavier plate dives beneath the less dense plate and sinks into the

Earth's mantle Earth's mantle is a layer of silicate mineral, silicate rock between the Earth's crust, crust and the Earth's outer core, outer core. It has a mass of and makes up 67% of the mass of Earth. It has a thickness of making up about 46% of Earth's ...

Notes and references

Literature

* * * * *

External links

* {{Portal bar, Switzerland Geology of the Alps World Heritage Sites in Switzerland Flims Tourist attractions in Switzerland Geography of the canton of Glarus Geography of Graubünden Geography of the canton of St. Gallen Glarus–Graubünden border Protected areas of the Alps

World Heritage

History

See also

Notes and references

Literature

External links