The Aarmassif or Aaremassif (German: ''Aarmassiv'') is a

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

massif in the

Swiss Alps The Alpine region of Switzerland, conventionally referred to as the Swiss Alps (german: Schweizer Alpen, french: Alpes suisses, it, Alpi svizzere, rm, Alps svizras), represents a major natural feature of the country and is, along with the Swiss ...

. It contains a number of large

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 m ...

s and parts of mountain chains.

Name

The massif is named after the

Aar AAR or Aar may refer to: Geography * Aar, a river in Switzerland, tributary of the Rhine *Aar (Lahn), a tributary of Lahn river in Germany, descending from the Taunus mountains * Aar (Dill), a tributary of Dill river in Germany, also in the bas ...

, a river that has its source in the Aarmassif.

Geography

The Aarmassif crops out in the eastern part of the Bernese Alps and the

Lepontine Alps , topo_map= Swiss Federal Office of Topography swisstopo , photo=MonteLeone0001.jpg , photo_caption=Monte Leone , country_type= Countries , country= , subdivision1_type= Cantons, Regions , subdivision1= , parent= Western Alps , borders_o ...

, roughly form Leukerbad in the west to the

Tödi The Tödi (), is a mountain massif and with the mountain peak Piz Russein the highest mountain in the Glarus Alps and the highest summit in the canton of Glarus, Switzerland. It is located on the border between the cantons of Graubünden, to the ...

in the east. Further east the massif only appears in small

windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

like the ''Vättner window'' between Gigerwald and Vättis in Sankt Gallen and at the

Limmerensee Limmernsee (or Limmerensee) is a reservoir in the Canton of Glarus, Switzerland, between the peaks of Muttenchopf (2,482 m), Selbsanft (2,950 m) and Kistenstöckli (2,746 m). It may be reached by aerial tramway or by foot from Linthal. The L ...

in the same

canton Canton may refer to: Administrative division terminology * Canton (administrative division), territorial/administrative division in some countries, notably Switzerland * Township (Canada), known as ''canton'' in Canadian French Arts and ent ...

Tectonics and lithology

The Aarmassif is part of the

Helvetic zone {{Geology of the Alps The Helvetic zone, Helvetic system or the Helveticum is a geologic subdivision of the Alps. The Helvetic zone crops out mainly in Switzerland, hence the name (derived from ''Helveticus'': Latin for Swiss). Rocks in the Hel ...

of the Alps, which consists of material originally from the European

tectonic plate Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

. The Aarmassif has

lithologies The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

common for

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

rocks all over Europe, deformed and metamorphosed during the Variscan orogeny. Younger

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s were eroded from this basement as a

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. If ...

brought the basement to the surface in the Alpine orogeny. Other places, where the European basement crops out in the Helvetic zone, are the mountain chains of the

Massif des Écrins The mountains of the Massif des Écrins (; Écrins Massif) form the core of Écrins National Park in Hautes-Alpes and Isère in the French Alps.Mont Blanc in the

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

and Italian Alps. The

of the basement rocks are mainly

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...

es,

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...

s and

amphibolite Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky ...

s. These were in some places intruded by

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

s after the Variscan orogeny, called Aare granite. During a late phase in the Alpine orogeny in the

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

the Aarmassif was uplifted in the form of a large elongated dome structure. The overlying limestones of the

Helvetic nappes {{Unreferenced, date=June 2019, bot=noref (GreenC bot) The Helvetic nappes (german: 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 ...

now have a very high dip angle, forming a ridge that appears at the

Eiger The Eiger () is a mountain of the Bernese Alps, overlooking Grindelwald and Lauterbrunnen in the Bernese Oberland of Switzerland, just north of the main watershed and border with Valais. It is the easternmost peak of a ridge crest that extends a ...

and south of the Jungfrau mountain.

Name

Geography

Tectonics and lithology

See also