The modern fjords was originated from the powerful glacial erosion of the Quaternary glaciers on crystalline rock complexes of the Paleozoic, providing the formation of sumptuous and exotic landscapes, such as those observed in Norway and its Fjords and rocky complexes.
This text contains an illustrated synthesis of the interesting geological history of the “top of the world” of Viking mythology: which encompasses the closing of the Jápeto Ocean, the collision of three micro-continents (including the legendary Avalon Peninsula), the formation of the Scandinavian mountains, and the later glacial origin of the fjords.
According to the Norse mythological writings of the Eddas, in these regions of peculiar geomorphological elements – with beautiful fjords, glacial circuses, valleys, escarpments and imposing cliffs, fantastic battles between gods and giants succeeded.
Caledonian Orogeny and the rocky complexes of Scandinavia
The mountain ranges of Scandinavia, Northern Europe and North America were built during the so-called Caledonian Orogeny, which occurred between about 490 and 390 million years ago in the Paleozoic era. These events were due to the closure of the Iapetus Ocean, from the convergence of continental lithospheric plates of Laurence, Baltic and Avalonia.
Following the disappearance of the ancient ocean, the cratons of the three paleocontinents formed a single landmass called Laurussia or Euroamerica (Figure 2). At a later stage, this continental mass was added to the supercontinent Pangea.
Following the subduction slip of the ancient Iapetus oceanic plate, subsequent continental collisions in Laurussia provided the generation of the long, folded mountain ranges (orogenesis) of the Scandinavian Alps, with metamorphism occurring in eclogytic facies.
In zones of strong compression, due to the shock of tectonic plates, reverse failures (push failures) and folding occur. At the converging limits, obduction processes usually occur, which allow the movement of rock chips from the basement of ancient oceanic crusts and from the upper mantle to the elevated parts of the continental crust.
These ancient rock fragments are known as opholiths, and can be found at high altitudes in some rugged chains. In the Norwegian peninsula of Folgefonn are found rocks from the pre-Cambrian on top of mountains over 1500 meters high, on younger filites.
The shear zones also comprise important geological structures of Norway, and these tectonic structures, rocky contrasts and the presence of the opholiths of the pre-Cambrian basement in the outcrops are noticeably noticeable from the fjords.
Tectonisms, denudation and penetration
After the formation of the immense and long mountain ranges and mountain ranges between 420 and 400 Ma (Silurian and Devonian periods), they had altitudes similar to those found in modern times in the Himalayas, above 8,000 meters.
Tectonism, fault reversal and gravitational collapse around 400 Ma, however, promoted the reduction of crustal thickness. The tectonic movements generated the thinning of the mountainous current, which also suffered processes of weathering and erosive wear of the surface (denudation), when the chain was included in the Pangea.
With the continuation of erosion, the chain reduction occurred, generating the process of peneplanation. Around 50 million years ago, there was a new tetonic survey of the pleneplanicium, which generated the current elevation contours of the Scandinavian Alps (Figure 3).
Glaciers and deployment of the Fjords
Derived from the Norwegian language – Fjord, the fjords are large inlets with penetration of waters into ancient glacial valleys through high rocky mountains. These huge entrails in relief can reach hundreds of miles inland.
This geomorphology, which presents abrupt unevenness, comes from dynamic erosive glacial work, coming from glaciers of the Quaternary glaciations, which formed deep valleys, many of them depressed below the current sea level.
The movement of immense masses of past ice towards the sea, as a function of gravitational force, generated glacial circuses, valleys and fjords, and the scenic regional landscapes of today. These glaciers contained high erosive potential and dragged sedimentary material of diverse nature, mainly from the igneous and less resistant Gnostic rocks of the high mountains.
In addition to the action of gravity, the movement of glaciers is also due to the properties of water flow in the solid state, whose crystal lattice in the form of ice provides lower density.
The main countries that house the emblematic fjords in their territories are Norway, Greenland, Chile and New Zealand. The west coast of Norway, also known as the country of the fjords, is very desiccated and has large numbers of glacial valleys invaded by the sea.
Quaternary glaciations and climate change
The final carving of the geological framework of modern fjords dates back to the last glacial period – Wisconsin or Weichsel Glaciation (Scandinavia), which occurred at the end of Pleistocene (between 110,000 and 11,000 years).
After the climate changes that decreed the closure of the most recent ice age, the waters of the seas occupied the old depressed basins and spaces excavated on the continental mountainous coast by glacial geological force (Figure 4).
Conclusion
Over millions of years, nature has forged the current forms of relief and landscapes of mythical Norway, a country that features many geotouristic attractions, such as the monumental glacial lakes, fjords and intriguing rocky complexes.
The main stages of the geological formation of the region include: the closure of the Iapetus Ocean; the continental collision of Laurence, Baltic and Avalonia; the formation of large mountain ranges and the Scandinavian Alps; tectonisms and denudation by erosion over millions of years; reduction and peneplanation of the ancient Cordilhiera; and glacial erosion with the formation of deep valleys and subsequent marine filling of the fjords.
The imposing walls of crystalline rocks of the ancient top of the world, present great unevenness and impressive cracks and landings, which could well be the secret passages and bridges of the portal of the Viking Bifrost, that enables the dimensional link between the domain of the Norse mythological Gods – Asgard and Midgard.
- This article about fjords and rocky complexes of Norway is part of a set of texts from Exploring the natural charms of the Old World to be integrated into an e-book
- Cover image: the Trolltunga (troll tongue), one of the main sights of Norway, which lies 700 meters above the lake Ringedalsvatnet. (author unknown)
- For more information on glacier erosion, see the post: Glacial erosion has carved beautiful lakes.
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References
Claes Grundsten e Göran Palmgren, Fjällboken, Estocolmo, Norstedt, 2010
Helland-Hansen, W. et al. (red.): Naturhistorisk vegbok for Hordaland. Bergen Museum-Nord 4. 2004.
Karianne Lilleøren. «Fjord» (em norueguês). Store norske leksikon (Grande Enciclopédia Norueguesa)
https://pt.frwiki.wiki/wiki/Alpes_scandinaves
https://stunningoutdoors.com/hiking-preikestolen-in-summer/
https://www.fjords.com/the-hardangerfjord-area-geology-and-landscape/
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