The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late
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 ' ...
continental collision between
Euramerica (Laurussia) and
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final st ...
to form the
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which lea ...
of
Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 millio ...
.
Nomenclature
The name ''Variscan'', comes from the Medieval
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
name for the district ''
Variscia'', the home of a Germanic tribe, the
Varisci;
Eduard Suess
Eduard Suess (; 20 August 1831 - 26 April 1914) was an Austrian geologist and an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana (proposed in 1861) and t ...
, professor of geology at the
University of Vienna
The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich h ...
, coined the term in 1880. (
Variscite, a rare green mineral first discovered in the
Vogtland
Vogtland (; cz, Fojtsko) is a region spanning the German states of Bavaria, Saxony and Thuringia and north-western Bohemia in the Czech Republic. It overlaps with and is largely contained within Euregio Egrensis. The name alludes to the forme ...
district of
Saxony
Saxony (german: Sachsen ; Upper Saxon: ''Saggsn''; hsb, Sakska), officially the Free State of Saxony (german: Freistaat Sachsen, links=no ; Upper Saxon: ''Freischdaad Saggsn''; hsb, Swobodny stat Sakska, links=no), is a landlocked state of ...
in Germany, which is in the Variscan belt, has the same etymology.)
''Hercynian'', on the other hand, derives from the
Hercynian Forest. Both words were descriptive terms of
strike directions observed by geologists in the field, ''variscan'' for southwest to northeast, ''hercynian'' for northwest to southeast. The ''variscan'' direction reflected the direction of ancient fold belts cropping out throughout Germany and adjacent countries and the meaning shifted from direction to the fold belt proper.
One of the pioneers in research on the Variscan fold belt was the German geologist
Franz Kossmat, establishing a still valid division of the European Variscides in 1927.
The other direction, ''Hercynian'', for the direction of the
Harz
The Harz () is a highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name ''Harz'' derives from the Middle High German w ...
Mountains in Germany, saw a similar shift in meaning. Today, ''Hercynian'' is often used as a
synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are al ...
for ''Variscan'' but is somewhat less used than the latter. In the United States, it is used only for European orogenies; the contemporaneous and genetically linked mountain-building phases in the
Appalachian Mountains
The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. The ...
have different names.
["The Hercynian Orogeny"](_blank)
Historical Geology, University of North Texas.
The regional term ''Variscan'' underwent a further meaning shift since the 1960s. Geologists generally began to use it to characterize late Paleozoic fold-belts and orogenic phases having an age of approximately 380 to 280 Ma.
Some publications use the term ''Variscan'' for fold belts of even younger age, deviating from the meaning as a term for the North American and European orogeny related to the Gondwana-Laurasia collision.
Distribution
The North American and European Variscan Belt includes the mountains of Portugal and Spain (
Galicia
Galicia may refer to:
Geographic regions
* Galicia (Spain), a region and autonomous community of northwestern Spain
** Gallaecia, a Roman province
** The post-Roman Kingdom of the Suebi, also called the Kingdom of Gallaecia
** The medieval King ...
, and
Pyrenees
The Pyrenees (; es, Pirineos ; french: Pyrénées ; ca, Pirineu ; eu, Pirinioak ; oc, Pirenèus ; an, Pirineus) is a mountain range straddling the border of France and Spain. It extends nearly from its union with the Cantabrian Mountains to ...
), southwestern Ireland (i.e.
Munster
Munster ( gle, an Mhumhain or ) is one of the provinces of Ireland, in the south of Ireland. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" ( ga, rí ruirech). Following th ...
),
Cornwall
Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlan ...
,
Devon
Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devon is ...
,
Pembrokeshire, the
Gower Peninsula
Gower ( cy, Gŵyr) or the Gower Peninsula () in southwest Wales, projects towards the Bristol Channel. It is the most westerly part of the historic county of Glamorgan. In 1956, the majority of Gower became the first area in the United Kingd ...
and the
Vale of Glamorgan
The Vale of Glamorgan ( cy, Bro Morgannwg ), often referred to as The Vale, is a county borough in the south-east of Wales. It borders Bridgend County Borough to the west, Cardiff to the east, Rhondda Cynon Taf to the north, and the Bristol ...
. Its effects are present in France from
Brittany
Brittany (; french: link=no, Bretagne ; br, Breizh, or ; Gallo: ''Bertaèyn'' ) is a peninsula, historical country and cultural area in the west of modern France, covering the western part of what was known as Armorica during the period o ...
, below the
Paris Basin
The Paris Basin is one of the major geological regions of France. It developed since the Triassic over remnant uplands of the Variscan orogeny (Hercynian orogeny). The sedimentary basin, no longer a single drainage basin, is a large sag in the ...
to the
Ardennes
The Ardennes (french: Ardenne ; nl, Ardennen ; german: Ardennen; wa, Årdene ; lb, Ardennen ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Be ...
, the
Massif Central
The (; oc, Massís Central, ; literally ''"Central Massif"'') is a highland region in south-central France, consisting of mountains and plateaus. It covers about 15% of mainland France.
Subject to volcanism that has subsided in the last 10,00 ...
, the
Vosges
The Vosges ( , ; german: Vogesen ; Franconian and gsw, Vogese) are a range of low mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single ...
and
Corsica.
The Variscan Belt reappears in
Sardinia
Sardinia ( ; it, Sardegna, label= Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label= Algherese and Catalan) is the second-largest island in the Mediterranean Sea, af ...
in Italy and in Germany where the
Rhine Massif
), Surselva, Graubünden, Switzerland
, source1_coordinates=
, source1_elevation =
, source2 = Rein Posteriur/Hinterrhein
, source2_location = Paradies Glacier, Graubünden, Switzerland
, source2_coordinates=
, source ...
(Ardennes,
Eifel
The Eifel (; lb, Äifel, ) is a low mountain range in western Germany and eastern Belgium. It occupies parts of southwestern North Rhine-Westphalia, northwestern Rhineland-Palatinate and the southern area of the German-speaking Community of ...
,
Hunsrück
The Hunsrück () is a long, triangular, pronounced upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued by the Taunus mountains, past ...
,
Taunus
The Taunus is a mountain range in Hesse, Germany, located north of Frankfurt. The tallest peak in the range is ''Großer Feldberg'' at 878 m; other notable peaks are ''Kleiner Feldberg'' (825 m) and '' Altkönig'' (798 m).
The Taunus range spans ...
and other regions on both sides of
Middle Rhine Valley), the
Black Forest
The Black Forest (german: Schwarzwald ) is a large forested mountain range in the state of Baden-Württemberg in southwest Germany, bounded by the Rhine Valley to the west and south and close to the borders with France and Switzerland. It is ...
and
Harz Mountains remain as testimony. In southern Iberia it is marked by a classic strike-slip suture zone between very distinct suspect terranes, and clear evidence can be seen of ductile shearing between high-grade
metamorphic rock
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 ...
s and lower grade sedimentary rocks in a wide belt north of the
Algarve
The Algarve (, , ; from ) is the southernmost NUTS II region of continental Portugal. It has an area of with 467,495 permanent inhabitants and incorporates 16 municipalities ( ''concelhos'' or ''municípios'' in Portuguese).
The region has its ...
and extending into the northernmost part the autonomous region of
Andalusia
Andalusia (, ; es, Andalucía ) is the southernmost autonomous community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a "historical nationality". The ...
and southern
Extremadura
Extremadura (; ext, Estremaúra; pt, Estremadura; Fala: ''Extremaúra'') is an autonomous community of Spain. Its capital city is Mérida, and its largest city is Badajoz. Located in the central-western part of the Iberian Peninsula, ...
.
In the Czech Republic and southwestern Poland the
Bohemian Massif is the eastern end of the unmodified Variscan belt of crustal deformation in Europe. Further Variscan developments to the southeast are partly hidden and
overprinted by the
Alpine orogeny. In the
Alps
The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, ...
a Variscan core is built by
Mercantour,
Pelvoux,
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 ...
,
Montblanc and
Aar Massif.
Dinaric, Greek and Turkish mountain chains are the southeastern termination of the Variscan proper.
The Variscan was contemporaneous with the
Acadian
The Acadians (french: Acadiens , ) are an ethnic group descended from the French who settled in the New France colony of Acadia during the 17th and 18th centuries. Most Acadians live in the region of Acadia, as it is the region where the ...
and
Alleghenian orogeny
The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 19 ...
in the United States and Canada, responsible for forming the
Ouachita and
Appalachian Mountains
The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. The ...
. North American areas with Variscan foldbelts include
New England
New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian province ...
,
Nova Scotia
Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland".
Most of the population are native En ...
and
Newfoundland and Labrador
Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
. The
Moroccan Meseta
The Moroccan Meseta or Western Meseta, are uplifted terranes of dominantly Palaeozoic rocks exposed along the Moroccan coastal block between the Atlantic Margin and the Middle Atlas.
Geology
The Meseta Domain, taking its name from Spain's Mese ...
and the
Anti-Atlas
The Anti-Atlas ( ar, الأطلس الصغير, shi, Aṭlas Mẓẓiyn), also known as Lesser Atlas or Little Atlas is a mountain range in Morocco, a part of the Atlas Mountains in the northwest of Africa. The Anti-Atlas extends from the Atlanti ...
in northwestern Africa show close relations to the Appalachian Mountains and used to form the eastern part of the
Appalachian orogeny before the opening of the
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
in
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 Mya. The J ...
times. 'Variscan' mountains in a broad chronological sense include the
Urals, the
Pamir, the
Tian Shan and other Asian foldbelts.
Paleogeographic configuration Lower Carboniferous
''Paleomap Project'' by C.Scotese. Accessed on December 29, 2007.
Formation
The Variscan orogeny involved a complicated heterogeneous assembly of different microplates and heterochronous collisions, making the exact reconstruction of the plate tectonic processes difficult. Plate convergence that caused the Caledonian orogeny in the Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoi ...
continued to form the Variscan orogeny in the succeeding Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...
and Carboniferous Periods. Both orogenies resulted in the assembly of a super-continent, Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 millio ...
, which was essentially complete by the end of the Carboniferous.
In the Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...
Period, a land mass, which has been named Gondwana (present day South America, Africa, Antarctica, Arabia
The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate. ...
, the Indian subcontinent
The Indian subcontinent is a physiographical region in Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian Ocean from the Himalayas. Geopolitically, it includes the countries of Bangladesh, Bhutan, India ...
, Zealandia
Zealandia (pronounced ), also known as ( Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L ...
and Australia), straddled the space between the South Pole
The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...
and the Equator
The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can al ...
on one side of the globe. Off to the west were three other masses: Laurentia
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...
, Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part o ...
and Baltica, located as if on the vertices of a triangle. To the south of them was a large archipelago, the terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its ow ...
Avalonia
Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of We ...
, rifted off the north Gondwana margin in early Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...
.
By the end of the Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoi ...
and in Early Devonian times, Baltica and Laurentia drifted towards each other, closing the Iapetus Ocean between them. They collided in the Caledonian orogeny and formed the Caledonide mountains of North America, Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is ...
, the British Isles and Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
. Seafloor spreading to the south of Avalonia pushed the latter into north Laurentia and thrust up the northern Appalachian Mountains in the acadian phase
The Acadians (french: Acadiens , ) are an ethnic group descended from the French who settled in the New France colony of Acadia during the 17th and 18th centuries. Most Acadians live in the region of Acadia, as it is the region where the d ...
of the Caledonian orogeny. Contemporaneously the Tornquist Sea between Avalonia and Baltica was entirely closed. Thus Avalonia formed the southern coast of the new continent Euramerica ( Laurussia, the Old Red Sandstone continent in present-day North America, the British Isles, northern Germany, Scandinavia and western Russia).
In late Devonian and in the Carboniferous the archipelago Armorica
Armorica or Aremorica ( Gaulish: ; br, Arvorig, ) is the name given in ancient times to the part of Gaul between the Seine and the Loire that includes the Brittany Peninsula, extending inland to an indeterminate point and down the Atlantic Co ...
of southern Europe, which had rifted off Gondwana after Avalonia later in the Ordovician, was pushed into Avalonia, creating a second range, the North American/European Variscan, to the east of the Caledonide/Appalachian. The collision of Gondwana proper with Laurussia followed in the early Carboniferous, when the Variscan belt was already in place and actively developing.
By the end of the Carboniferous, Gondwana had united with Laurussia on its western end through northern South America and northwestern Africa. Siberia was approaching from the northeast, separated from Laurussia only by shallow waters. Collision with Siberia produced the Ural Mountains
The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through western ...
in the latest Paleozoic and completed the formation of Pangaea. Eastern Laurussia was still divided from Gondwana by the Paleotethys Ocean. In the Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
Period of 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 ...
Era, animals could move without oceanic impediment from Siberia over the North Pole to Antarctica over the South Pole. In the Mesozoic Era, rifting and subsequent opening of the Atlantic split Pangaea. As a consequence, the Variscan Belt around the then periphery of Baltica ended up many hundreds of miles from the Appalachians.
Notes
Further reading
*
*
*
*
*
External links
* Christopher R. Scotese, Paleomap Project:
*
Early Devonian Map
*
*
*
* Ronald Blakey, Colorado Plateau Geosystems Inc
Europe in the Late Carboniferous
{{Authority control
Hercynian orogeny
Paleozoic Europe
Natural history of Europe
Geology of Devon