The geology of Norway encompasses the history of Earth that can be interpreted by rock types found in

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 ...

, and the associated

sedimentological Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation (erosion and weathering), transport, deposition and diagenesis. Sedimentologists apply their understanding of mo ...

history of soils and rock types. The Norwegian mountains were formed around 400 million years ago (Ma) during the

Caledonian orogeny The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occ ...

Precambrian

Rocks of

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth Earth ...

age in Norway are confined to a few 10 km-scale areas within younger metamorphic belts exposed on islands off the west coast of northern Norway and as smaller fragments locally in the

Western Gneiss Region The Western Gneiss Region ( no, Gneisregionen) is a large geological unit in Norway chiefly made of gneiss rock that formed through metamorphism during the Caledonian orogeny. It makes up a tectono-stratigraphic terrane of the Scandinavian Caledon ...

in south-central Norway. Despite intense reworking during the

in some areas, three major belts can be recognised in the

Proterozoic The Proterozoic () is a geological eon spanning the time interval from 2500 to 538.8million years ago. It is the most recent part of the Precambrian "supereon". It is also the longest eon of the Earth's geologic time scale, and it is subdivided ...

rocks of Norway, the

Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is ...

and

Mesoproterozoic The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), ...

Gothian and Sveconorwegian, the

Palaeoproterozoic The Paleoproterozoic Era (;, also spelled Palaeoproterozoic), spanning the time period from (2.5–1.6 Ga), is the first of the three sub-divisions ( eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's ...

Svecokarelian and the intervening Transscandinavian Igneous Belt of late Palaeoproterozoic age. About 1400 million years ago in the Mesoproterozoic tectonic extension and continental magmatism led to the formation of

Kattsund-Koster dyke swarm The Kattsund-Koster dyke swarm is a collection of dykes of Mesoproterozoic age in southeastern Norway and the West Coast of Sweden. The most prominent outcrops are in the Koster Islands in Sweden and Kattsund in Norway, hence the name. The dykes ...

in southeastern Norway.

Neoproterozoic

The later part of the Neoproterozoic records the break-up of the Rodinia

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...

and the formation of the Iapetus Ocean. Passive margin sequences are preserved within the lowermost

allochthon upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a nappe. If an erosional hole is created in the nappe that is called a window (geology)">window. A klippe is a solitary out ...

and parautochthon of the Caledonian

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 syst ...

sheets. In southern Norway the sequence is known as ''Sparagmite''. The

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be ...

changes from

fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...

in the parautochthon to deepwater marine in the lowermost allochthon consistent with a

paleogeography Palaeogeography (or paleogeography) is the study of historical geography, generally physical landscapes. Palaeogeography can also include the study of human or cultural environments. When the focus is specifically on landforms, the term pale ...

of an originally westward deepening basin. The uppermost part of the Neoproterozoic sequence throughout Norway includes a

tillite image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

, a record of the Varanger

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

which occurred between roughly 630-590 Ma, the final part of the

Cryogenian The Cryogenian (from grc, κρύος, krýos, meaning "cold" and , romanized: , meaning "birth") is a geologic period that lasted from . It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by ...

Period. This was followed by fluvial and shallow water marine deposits of the

Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and th ...

before a major marine transgression at the start of the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

Early Palaeozoic

The early Palaeozoic history of Norway is recorded in sequences preserved either as autochthon or at various levels within the allochthon. They relate to the further widening of Iapetus during the Cambrian, the start of closure during the Early

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

with the accretion of

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 own ...

s and

ophiolite An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks. The Greek word ὄφις, ''ophis'' (''snake'') is found ...

obduction Obduction is a geological process whereby denser oceanic crust (and even upper mantle) is scraped off a descending ocean plate at a convergent plate boundary and thrust on top of an adjacent plate. When oceanic and continental plates converge ...

during the Late Ordovician and continent-continent collision at 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 Paleozo ...

Caledonian orogeny

Within the entire exposed 1800 kilometre length of this

orogenic belt An orogenic belt, or orogen, is a zone of Earth's crust affected by orogeny. An orogenic belt develops when a continental plate crumples and is uplifted to form one or more mountain ranges; this involves a series of geological processes collecti ...

the following sequence is recognised from the base upwards: * Autochthon :: undisturbed foreland of the Baltic plate * Parautochthon ::

sheets that have moved only a short distance (up to tens of km) from their original position * Lower

:: far travelled thrust sheets derived from the Baltic plate

passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creat ...

, mainly sediments associated with the break-up of Rodinia * Middle allochthon :: also derived from the margin of the Baltic plate,

basement and its psammitic cover * Upper allochthon :: thrust sheets including

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alon ...

and ophiolitic sequences * Uppermost allochthon :: thrust sheets containing sediments with fossil assemblages indicating an origin on the margin of the Laurentian plate This vertically stacked sequence thus represents the

s of Baltica and Laurentia and intervening island arcs and back-arc basins telescoped together and emplaced on top of the Baltic Shield, involving hundreds of kilometres of shortening.

Devonian

Devonian age continental sediments are exposed in three main areas in and around mainland Norway; the

Solund Solund is a municipality in the county of Vestland, Norway. It is located in the traditional district of Sogn. Solund is the westernmost island municipality in Norway. Holmebåen on the island of Steinsøy is the westernmost point in all of Norw ...

, Kvamshesten, Håsteinen and

Hornelen Hornelen is a mountain in Bremanger Municipality in Vestland county, Norway. The mountain sits on the eastern end of the island of Bremangerlandet, along the Frøysjøen strait, in the Nordfjord region of Norway. At , it is the highest sea cli ...

basins along the west coast between

Sognefjord The Sognefjord or Sognefjorden (, en, Sogn Fjord), nicknamed the King of the Fjords ( no, Fjordenes konge), is the largest and deepest fjord in Norway. Located in Vestland county in Western Norway, it stretches inland from the ocean to the smal ...

and

Nordfjord Nordfjord ( en, Northern fjord—in contrast to Sunnfjord) is a traditional district of Norway. Geography The region is located in the northern part of Vestland county in Western Norway. It centers on the Nordfjorden and it comprises the muni ...

, on the islands of

Smøla Smøla is a municipality in Møre og Romsdal county, Norway. It is part of the Nordmøre region. The administrative centre of the municipality is the village of Hopen, other villages include Dyrnes, Råket, and Veiholmen. The municipality i ...

Hitra Hitra is a municipality in Trøndelag county, Norway. The municipality covers the island of Hitra and hundreds smaller islands, islets, and skerries. It is part of the Fosen region. The administrative centre of the municipality is the village ...

and the western end of the

Fosen Fosen is a traditional district in Trøndelag, consisting of the municipalities Osen, Roan Åfjord, Ørland, Indre Fosen, Orkland, Heim, Hitra and Frøya. The district is dominated by forested valleys, lakes, coastal cliffs but also shallow ar ...

Peninsula in Trøndelag and at Røragen near

Røros Røros ( sma, Plaassja, ) is a municipality in Trøndelag county, Norway. The administrative centre of the municipality is the town of Røros. Some of the villages in Røros include Brekken, Glåmos, Feragen, Galåa, and Hitterdalen. The minin ...

close to the Swedish border. Further Devonian deposits are found on Svalbard. During the

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, whe ...

Period the thickened welt of crust formed by the Caledonian orogeny began to collapse. Some thrust surfaces show evidence of reactivation as low-angle extensional faults, but the main structures formed at this time were large-scale extensional detachments. Movement on these detachments led to deposition of thick sequences of continental clastic sediments in their hanging walls and was in part responsible for the exhumation of late Caledonian ultra high-pressure

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, causin ...

s, including

eclogite Eclogite () is a metamorphic rock containing garnet (almandine- pyrope) hosted in a matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, ...

s, in their footwalls. The displacements on these structures range from nearly orthogonal to the Caledonian chain in the south to being strongly oblique in mid-Norway.

Carboniferous

The only

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

age strata preserved onshore are found on

Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...

. Rocks of this age have also been proved by drilling beneath the

Barents Sea The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea of the Arctic Ocean, located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territo ...

, but nowhere else on the Norwegian continental shelf.

Permian

In southern Norway the

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 ...

was a period of W-E directed

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ing with associated igneous activity, during which the

Oslo graben The Oslo Graben or Oslo Rift is a graben formed during a geologic rifting event in Permian time, the last phase of the Variscan orogeny. The main graben forming period began in the late Carboniferous, which culminated with rift formation and volcan ...

formed.

Triassic

The only

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 ...

rocks preserved onshore are found on Svalbard but strata of this age are also widely known from the results of exploration drilling along the entire continental shelf.

Jurassic

Rocks of

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 ...

age are exposed onshore at one locality on

Andøya Andøya is the northernmost island in the Vesterålen archipelago, situated about inside the Arctic circle. Andøya is located in Andøy Municipality in Nordland county, Norway. The main population centres on the island include the villages of ...

and have been discovered nearshore and beneath one fjord (Beitstadsfjord) northeast of Trondheim. As with the Triassic, Jurassic strata have a wide distribution along the whole continental shelf. They were dominantly deposited in a

deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarel ...

to shallow marine environment. The Late Jurassic was the main rifting phase in the Central

Graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

, Viking Graben, More Basin, Vøring Basin and on the Barents shelf. This was also the period of deposition of the main

source rock In petroleum geology, source rock is rock which has generated hydrocarbons or which could generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been depos ...

that has generated most of the

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

discovered in the offshore areas.

Cretaceous

The Late Jurassic basins offshore were infilled and onlapped by the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

post-rift sequence. These are dominated by

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

s although the Upper Cretaceous sequence from the Viking Graben and south is dominated by

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chalk ...

. In the outer parts of the Vøring margin rifting restarted in the late Cretaceous, continuing through to the early

Palaeocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palai� ...

. This event is interpreted to be a precursor to the break-up of the North Atlantic. Little is known of the then elevation of what would be the area of current day Norway.

References

* Ramberg, I.B., Bryhni, I, & Nøttvedt, A. (ed.) (2007). ''Landet blir til (Norges geologi)''. Trondheim, Norsk Geologisk Forening.

External links

Interactive geological map of Norway
{{Geology of Europe