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The Austroalpine nappes are a geological
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
 nappe stack in the European Alps
Alps

The Alps is the name for one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west....
. The Alps contain three such stacks, of which the Austroalpine nappes are structurally
Structural geology

Structural geology is the study of the three-dimensional distribution of Rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation in the rocks, and ultimately, to understand the stress field t...
 on top of the other two (meaning they were thrust
Thrust

Thrust is a reaction force described quantitatively by Isaac Newton's Newton's laws of motion. When a system expels or acceleration mass in one direction the accelerated mass will cause a proportional but opposite force on that system....
ed over the other two). The name Austroalpine means Eastern Alpine, because these nappes crop out
Outcrop

Outcrop is a Geology term referring to the appearance of bedrock or superficial deposits exposed at the surface of the Earth. In most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be seen or examined closely....
 mainly in the Eastern Alps
Eastern Alps

Eastern Alps is the name given to the eastern half of the Alps, usually defined as the area east of the Spl?gen Pass in eastern Switzerland. North of the Spl?gen Pass, the Posterior Rhine forms the border, and south of the pass, the Liro river and Lake Como form the boundary line....
 (the Alps east of the line Lake Constance
Lake Constance

Under the designation Lake Constance one summarizes the three independent Body of water Obersee , Untersee and Seerhein , lying in the northern Alps foreland....
 - Chur
Chur

Chur ; ; Latin: Curia, Curia Rhaetorum and Curia Raetorum) is the capital of the Switzerland Cantons of Switzerland of Graub?nden and lies in the northern part of the canton....
 – Lake Como
Lake Como

Lake Como is a lake of Glacier origin in Lombardy, Italy. It has an area of 146 km?, making it the third largest lake in Italy, after Lake Garda and Lake Maggiore....
).

Because the Austroalpine nappes consist of material from the former Apulian or Adriatic plate
Apulian Plate

The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period....
 that was thrusted over the European plate they are called allochthon
Allochthon

* In structural geology, an allochthon is a large block of rock which has been moved from its original site of formation, usually by thrust fault ....
 nappes.






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The Austroalpine nappes are a geological
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
 nappe stack in the European Alps
Alps

The Alps is the name for one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west....
. The Alps contain three such stacks, of which the Austroalpine nappes are structurally
Structural geology

Structural geology is the study of the three-dimensional distribution of Rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation in the rocks, and ultimately, to understand the stress field t...
 on top of the other two (meaning they were thrust
Thrust

Thrust is a reaction force described quantitatively by Isaac Newton's Newton's laws of motion. When a system expels or acceleration mass in one direction the accelerated mass will cause a proportional but opposite force on that system....
ed over the other two). The name Austroalpine means Eastern Alpine, because these nappes crop out
Outcrop

Outcrop is a Geology term referring to the appearance of bedrock or superficial deposits exposed at the surface of the Earth. In most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be seen or examined closely....
 mainly in the Eastern Alps
Eastern Alps

Eastern Alps is the name given to the eastern half of the Alps, usually defined as the area east of the Spl?gen Pass in eastern Switzerland. North of the Spl?gen Pass, the Posterior Rhine forms the border, and south of the pass, the Liro river and Lake Como form the boundary line....
 (the Alps east of the line Lake Constance
Lake Constance

Under the designation Lake Constance one summarizes the three independent Body of water Obersee , Untersee and Seerhein , lying in the northern Alps foreland....
 - Chur
Chur

Chur ; ; Latin: Curia, Curia Rhaetorum and Curia Raetorum) is the capital of the Switzerland Cantons of Switzerland of Graub?nden and lies in the northern part of the canton....
 – Lake Como
Lake Como

Lake Como is a lake of Glacier origin in Lombardy, Italy. It has an area of 146 km?, making it the third largest lake in Italy, after Lake Garda and Lake Maggiore....
).

Because the Austroalpine nappes consist of material from the former Apulian or Adriatic plate
Apulian Plate

The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period....
 that was thrusted over the European plate they are called allochthon
Allochthon

* In structural geology, an allochthon is a large block of rock which has been moved from its original site of formation, usually by thrust fault ....
 nappes. In comparison with the other nappe stacks they have experienced lower grade metamorphism
Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
, which distinguishes them clearly from the Penninic nappes
Penninic nappes

The Penninic nappes or the Penninicum are one of three nappe stacks and geology zones in which the Alps can be divided. In the western Alps the Penninic nappes are more obviously present than in the eastern Alps , where they outcrop as a narrow band....
 on which they rest.

Lithologies

The Austroalpine nappes are fragments of the former continental shelf
Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during Ice age such as the current epoch by relatively shallow seas and Bay....
 and continental slope of the Apulian or Adriatic plate
Apulian Plate

The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period....
. These fragments contain rocks from the continental basement
Basement (geology)

In geology, the terms basement and crystalline basement are used to define the rocks below a sedimentation platform or cover, or more generally any rock below sedimentary rocks or sedimentary basin that are metamorphic rock or Igneous rock in origin....
 as well as from sedimentary rock
Sedimentary rock

Sedimentary rock is one of the three main Rock types . Sedimentary rock is formed by deposition and consolidation of mineral and organic material and from precipitation of minerals from solution....
s deposited in these environments.

The basement rocks have experienced metamorphism
Metamorphism

Metamorphism is the solid-state Crystallization of pre-existing Rock due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids....
 related to their original depth in the Earth’s crust
Crust (geology)

In geology, a crust is the outermost solid shell of a planet or moon, which is chemically distinct from the underlying mantle . Crusts of Earth , our Moon, Mercury , Venus, and Mars have been generated largely by igneous processes, and these crusts are richer in incompatible elements than their respective mantle s....
, but in the Austroalpine nappes Alpine
Alpine orogeny

The Alpine orogeny is an orogeny phase in the Tertiary that formed the mountain ranges of the Alpide belt. These mountains include the Atlas Mountains, the Pyrenees, the Alps, the Dinaric Alps, the Pindus, the Carpathians, the Balkan Mountains, the Taurus Mountains, the Caucasus Mountains, the Alborz, the Zagros Mountains, the Hindu Kush, t...
 metamorphism (i.e. metamorphism related to the formation of the Alps) is fairly low grade to non-existent. The basement rocks can be greenschist facies to amphibolite facies, depending on their original depth. They are Paleozoic
Paleozoic

The Paleozoic or Palaeozoic Era is the earliest of three geology Era of the Phanerozoic Eon . The Paleozoic spanned from roughly , and is subdivided into six period ; from oldest to youngest they are: the Cambrian, Ordovician, Silurian, Devonian period, Carboniferous, and Permian...
 schist
Schist

The schists form a group of Erins metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, Chlorite group, talc, hornblende, graphite, and others....
s and (para-)gneiss
Gneiss

Gneiss is a common and widely distributed type of Rock formed by high-grade regional metamorphic rock processes from pre-existing formations that were originally either igneous rock or Sedimentary rock rocks....
es intruded by granite
Granite

Granite is a common and widely occurring type of Intrusion , felsic, igneous rock rock . Granite has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as Porphyry ....
s of Variscan
Variscan orogeny

The Variscan orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Laurasia and Gondwana to form the supercontinent of Pangea....
 and Tertiary
Tertiary

The Tertiary is a a term for a Geologic time scale#Terminology 65 million to 1.8 million years ago. The Tertiary covered the time span between the superseded Secondary period and an out-of-date definition of the Neogene#Controversy....
 age.

On top of this basement Permian
Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Roderick Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian system" after the ancient kingdom...
 and Mesozoic
Mesozoic

The Mesozoic Era is one of three Geologic time scale of the Phanerozoic eon . The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' ....
 sedimentary and volcanic rock
Volcanic rock

Volcanic rock is an igneous rock of Volcano origin.Texture Volcanic rocks are usually fine-grained or aphanitic to glassy in texture....
s were deposited. Shallow marine limestone
Limestone

File:Limestone Formation In Waitomo.jpgLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geology record....
s are abundant, these limestones now form the mountain chains of the northern part of the Eastern Alps, which are therefore together called the Northern Calcareous Alps. Sometimes the limestone has been turned into dolomite
Dolomite

Dolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate calciummagnesium2 found in crystals....
, as in the Austria
Austria

Austria , officially the Republic of Austria , is a landlocked country in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west....
n region Salzkammergut
Salzkammergut

The Salzkammergut is a resort area located in Austria. It stretches from Salzburg to the Dachstein mountain range, spanning the States of Austria of Upper Austria , Salzburg , and Styria ....
 and the German
Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
 region Allgäu
Allgäu

Allg?u is a Germany region in the southwest of Bavaria also extending some kilometres into southeastern Baden-W?rttemberg. The region stretches from the prealpine lands up to the Alps....
.

A special unit is the greywacke zone
Greywacke zone

The greywacke zone is a band of Paleozoic sedimentary rocks in the Austrian Alps. The zone is part of the Austroalpine nappes.Mesozoic limestones crop out north of the greywacke zone, forming the Northern Calcareous Alps....
, a band of Paleozoic
Paleozoic

The Paleozoic or Palaeozoic Era is the earliest of three geology Era of the Phanerozoic Eon . The Paleozoic spanned from roughly , and is subdivided into six period ; from oldest to youngest they are: the Cambrian, Ordovician, Silurian, Devonian period, Carboniferous, and Permian...
 metamorphosed sedimentary rocks that forms an east-west band through the Austrian Alps. The greywacke zone crops out between the Mesozoic rocks of the Northern Calcareous Alps and the Austroalpine and Penninic basement rocks of the Central Eastern Alps
Central Eastern Alps

The Central Eastern Alps are the core mountain range of the Eastern Alps with the highest peaks, located between the Northern Limestone Alps and the Southern Limestone Alps, from which they differ in geological composition....
. Stratigraphically
Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary rock and layered volcanic rocks....
 the greywacke zone can be up to 2 km thick.

All of these lithologies were folded and thrusted, so that the basement can be found on top of the sediments and vice versa.

Geographic position

In Switzerland
Switzerland

Switzerland is a landlocked Swiss Alps country of roughly 7.7 million people in Western Europe with an area of 41,285 km?. Switzerland is a federal republic consisting of 26 states called Cantons of Switzerland....
 the Austroalpine nappes have been eroded
Erosion

For morphological image processing operations, see Erosion 'For use of in dermatopathology, see Erosion Erosion is the removal of solids in the natural environment....
 away except for a few isolated outcrops called the Sesia unit
Sesia unit

The Sesia unit or Sesia nappe, also called the Sesia-Dent Blanche unit is a tectonics unit or terrane in the Switzerland and Italy Alps....
 and the Dent Blanche klippe
Dent Blanche klippe

The Dent Blanche nappe or Dent Blanche klippe is a geology nappe and klippe that outcrop in the Pennine Alps. The nappe is Tectonostratigraphy on top of the Penninic nappes and by most researchers seen as Austroalpine nappes....
 (the Matterhorn
Matterhorn

The Matterhorn , Cervino or Cervin , is a mountain in the Pennine Alps. With its high summit, lying on the border between Switzerland and Italy, it is one of the highest peaks in the Alps and its north face is one of the Great north faces of the Alps....
 is the most outstanding example of an Austroalpine klippe
Klippe

A klippe is a geological feature of thrust fault terranes. The klippe is the remnant portion of a nappe after erosion has removed connecting portions of the nappe....
). These remaining Swiss nappes have a different tectonic and metamorphic history than their counterparts in Austria, which is why they are not always seen as a part of the Austroalpine nappes.

On the other hand, in Austria the Austroalpine nappes cover the largest part of that country, except for a few windows
Window (geology)

A tectonics window Windows can be almost any size, from a couple of meters to hundreds of kilometers....
 like the Hohe Tauern window
Hohe Tauern window

The Hohe Tauern window is a geological structure in the Austrian Central Eastern Alps. It is a window in the Austroalpine nappes where high-grade metamorphic rocks of the underlying Penninic nappes outcrop....
 and the Engadin window.

Traces of the Eo-Alpine orogenic phase

Before the formation of the Alps in the lower and middle Tertiary
Tertiary

The Tertiary is a a term for a Geologic time scale#Terminology 65 million to 1.8 million years ago. The Tertiary covered the time span between the superseded Secondary period and an out-of-date definition of the Neogene#Controversy....
 period, the Austroalpine rocks experienced another deformation
Deformation

In materials science, deformation is a change in the shape or size of an object due to an applied force . This can be a result of tensile strength forces, compressive strength forces, Simple shear, bending or torsion ....
 phase: the Eo-Alpine phase of mountain building that took place in the Cretaceous
Cretaceous

The Cretaceous , usually abbreviated K for its German translation Kreide, is a geologic period from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period....
. The metamorphic field gradient is to the east-south-east, so in a west-north-western direction the traces become less severe. In the west of Switzerland the event cannot be recognized anymore. In Austria, however, Eo-Alpine eclogite
Eclogite

Eclogite is a coarse-grained mafic metamorphic rock. Eclogite is of special interest for at least two reasons. First, it forms at pressures greater than those typical of the Crust of the Earth....
 lenses occur close to the Hohe Tauern window.

The Eo-Alpine phase is sometimes seen as the earliest phase of the Alpine orogeny. However, after the initial mountain building the tectonic plate
Tectonic Plate

#REDIRECT Plate tectonics...
s moved away from each other. The next phase was more than 50 Ma
Annum

Annum is one form of the Latin noun meaning year, not a form normally used for derivatives in modern languages: the accusative case Grammatical number of the second declension grammatical gender noun annus , anni ....
 later, so the events are often seen as unrelated.