An external massif is, in the

geology of the Alps The Alps form part of a Cenozoic orogenic belt of mountain chains, called the Alpide belt, that stretches through southern Europe and Asia from the Atlantic all the way to the Himalayas. This belt of mountain chains was formed during the Alpin ...

, a place where

crystalline rock A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s of the

European plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

crop out. Such

massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

s are found north and west of the

Penninic zone The Penninic nappes or the Penninicum, commonly abbreviated as Penninic, are one of three nappe stacks and geological zones in which the Alps can be divided. In the western Alps the Penninic nappes are more obviously present than in the eastern ...

(the crystalline "core" of the Alps) as tectonic windows in 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 ...

. They differ from the crystalline nappes in that they were originally part of the European plate, while the Penninic nappes were part of the crust below various domains in the

Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...

.Schmid ''et al.'' (2004) The external massifs are the

Argentera Argentera is a ''comune'' (municipality) in the Province of Cuneo in the Italian region Piedmont, located about southwest of Turin and about west of Cuneo, on the border with France. It consists of a series of sparse hamlets in the upper Valle ...

in the

Alpes Maritimes Alpes-Maritimes (; oc, Aups Maritims; it, Alpi Marittime, "Maritime Alps") is a department of France located in the country's southeast corner, on the Italian border and Mediterranean coast. Part of the Provence-Alpes-Côte d'Azur region ...

, the Pelvoux massif and the

Belledonne Belledonne (french: link=no, La chaine de Belledonne, ) is a mountain range (french: link=no, massif) in the Dauphiné Alps (part of the French Alps) in southeast France. The southern end of the range forms the eastern wall of the mountains th ...

range in the

Dauphiné The Dauphiné (, ) is a former province in Southeastern France, whose area roughly corresponded to that of the present departments of Isère, Drôme and Hautes-Alpes. The Dauphiné was originally the Dauphiné of Viennois. In the 12th centu ...

part of the French Alps, the

Aiguilles Rouges The Aiguilles Rouges ("Red Needles") are a crystalline mountainous massif of the French Prealps, opposite the Mont Blanc Massif. The colour of the iron rich gneiss (metamorphique) mountains gives the range its name. The highest summit is the Aig ...

in the

Savoy Savoy (; frp, Savouè ; french: Savoie ) is a cultural-historical region in the Western Alps. Situated on the cultural boundary between Occitania and Piedmont, the area extends from Lake Geneva in the north to the Dauphiné in the south. ...

part of the French Alps, the

Mont Blanc Massif The Mont Blanc massif (french: Massif du Mont-Blanc; it, Massiccio del Monte Bianco) is a mountain range in the Alps, located mostly in France and Italy, but also straddling Switzerland at its northeastern end. It contains eleven major indepen ...

at the borders between France, Italy and Switzerland and the

Aarmassif The Aarmassif or Aaremassif (German: ''Aarmassiv'') is a geologic massif in the Swiss Alps. It contains a number of large mountain chains and parts of mountain chains. Name The massif is named after the Aar, a river that has its source in the A ...

and Gotthardmassif in the

Central Alps The Alps form a large mountain range dominating Central Europe, including parts of Italy, France, Switzerland, Liechtenstein, Austria, Slovenia, Germany and possibly Hungary (if one includes the Kőszeg Mountains). This article describes the de ...

of Switzerland. The massifs are composed of the

basement A basement or cellar is one or more Storey, floors of a building that are completely or partly below the storey, ground floor. It generally is used as a utility space for a building, where such items as the Furnace (house heating), furnace, ...

of the former margin of the European plate, consisting of

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, cau ...

and

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or l ...

s of Hercynian age or older. The

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 Creta ...

cover that was originally on top of these rock has mostly been

detached A stand-alone house (also called a single-detached dwelling, detached residence or detached house) is a free-standing residential building. It is sometimes referred to as a single-family home, as opposed to a multi-family residential dwelling ...

by thin skinned

thrusting 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 ...

about 40 to 25 million years ago ( Ma).Pfiffner (2009) At some places along the Aarmassif, the Mesozoic cover is partly still lying conformally on top of the Hercynian basement rock, this Mesozoic is called the

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 partl ...

. The uplift that brought the massifs to the surface involved thick skinned thrusting (the style of thrusting in which the basement is itself involved) and took place in a tectonic phase beginning around 19 million years ago.

References

*; 2009: ''Geologie der Alpen'', Haupt Verlag, Berne, . *{{aut, Schmid, S.M.; Fügenschuh, B.; Kissling, E. & Schuster, R.; 2004: ''Tectonic map and overall architecture of the Alpine orogen'', Eclogae Geologicae Helveticae 97, pp 93–117. Geology of the Alps