Making of a Land - Chapter 3

Illustrations chapter 3.

Illustrations can be downloaded in the gallery further down.

 

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 Chapter 03 - p. 62-63

(Illustration:Bogdan Bocianowski. Photo:P.Aas, both NHM, Univ. of Oslo)

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Chapter 03 - p.64 

Photograph of a polished surface of 2800 million-yeard-old gneiss from Grasbakken on the south side of Varangerfjorden, Finnmar. The rock has a tonalitic composition and contains reddish veins of quartz and feldspar which have given the rock its commercial name of "Barents red". (Foto: NGU)

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Chapter 03 - p. 67

Cores of Archaen crust are preserved in all the major continents on the Earth. The earliest rocks that were formed may have been destroyed by meteorite impacts, tectonic prosesses, surface weathering and erosion, or they may be covered by younger strata. Rocks that are older than 3500 million years are only preserved in a few areas.

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Chapter 03 - p. 68

Simplified geological map of the Fennoscandian Shield. The map shows the broad divisions of the bedrock according to its age and the types of rock.

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Chapter 03 - p. 69

Dickinsonia from the White Sean. The fossil is 75 mm across. Museum of Natural History, Tøyen. (Photo: J.H. Hurum)

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Chapter 03 - p. 70

The principle of age determination. The ratio between mother and daughter isotopes in a mineral or rock is measured. Their known half-life is then used to calculate the length of time that has ensued since the process started from the original state, and this gives the age of the mineral or rock.

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Chapter 03 - p. 72

Geological map of the Kola Peninsula and eastern Finnmark showing the distribution of the most imprtant geological units and how they correlate with adjacent areas on the Kola Peninsula and in Finland. On Finnmarksvidda, Neoproterozoic to Cambrian strata rest with an angular unconformity on the basement. These deposits are overlain by nappes belonging to the Caledonian mountain chain which conceal the ancient basement rocks in the fjord districts of Troms and Finnmark.

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Chapter 03 - p. 74

Monozonitic plutonic rock inruded the gneisses in Sør-Varanger 2750 million years ago. The monozite has angular fragments of dark rocks and is transected by a pale-pink pegmatite dyke. Skallvåg, Sør-Varanger. (Foto: Ø. Nordgulen)

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Chapter 03 - p. 75

Unconformity at Skrukkebukt in Pasvik. Conglomerate has filled in an uneven surface where eroision has cut down into foliated ARchaean gneiss. (Foto:V.Melezhik)

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Chapter 03 - p. 77

The figures illustrate the geological evolution of the north-eastern part of the Fennoscandian Shield in the Early Proterozoic.

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Chapter 03 - p. 78a

Schematic drawing showing how the quartz-banded iron ore in Sør-Varanger probably formed. Free oxygen (O2) and iron ions formed the iron oxides, magnetite (Fe3O4) or haematite (Fe2O3) (dark bands in the figure). These are seperated by layers of precipitated jasper (yellow bands). Each band may be from one milimetre up to a few centimetres thick.

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Chapter 03 - p. 78b

The iron ore, which consists of alternating bands of quartz and magnetite that are 2-10 mm thick, occurs in the middle of the Bjørnevann Group. (Photo: Ø. Nordgulen)

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Chapter 03 - p. 79a

A geophysical map shoing the total magnetic field of part of Finnmarksvidda (the Kautokeino Greenstone Belt). (Figures: O.Olesen and J.S. Sandstad)

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Chapter 03 - p. 79b

The bedrock map illustrates part (framed) of the geophysical map. It shows how the geophysical properties of the bedrock can be used as a valuable aid when mapping areas covered by superficial deposits. (Figures: O.Olesen and J.S. Sandstad)

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Chapter 03 - p. 80a

Searching for gold in the bedrock beneath a thick cover of till requires heavy-duty equipment. Sáotgejohka 1990. (Photo:M. Often)

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Chapter 03 - p. 80b

Washing gold in the Goššjohka i 1901. (NGU's photo archive)

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Chapter 03 - p. 80c

Gold from Finnmark. The largest grain is about 2 mm. (Photo: B.M. Messel)

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Chapter 03 - p. 82a

The rocks of the Raipas Group tell an exciting geological story. Fluid basalt lava (brown) poured out of joint systems in a marine rift basin (a) and was followed by explosive volcanic eruptions (b) which gave rise to tuffs (light green). At the same time, the rift zone sank in fits and starts, resulting in the formation of a thick volcanic sequence (Kvenvik Greenstone), C). The basin was subsequently filled, initially by carbonate sediments (Storviknes dolomite) and finally by thick continental sandstones (Skoadduvarri sandstoene).

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Chapter 03 - p. 83b

The rocks of the Raipas Group tell an exciting geological story. Fluid basalt lava (brown) poured out of joint systems in a marine rift basin (a) and was followed by explosive volcanic eruptions (b) which gave rise to tuffs (light green). At the same time, the rift zone sank in fits and starts, resulting in the formation of a thick volcanic sequence (Kvenvik Greenstone), C). The basin was subsequently filled, initially by carbonate sediments (Storviknes dolomite) and finally by thick continental sandstones (Skoadduvarri sandstoene).

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Chapter 03 - p. 82c

The rocks of the Raipas Group tell an exciting geological story. Fluid basalt lava (brown) poured out of joint systems in a marine rift basin (a) and was followed by explosive volcanic eruptions (b) which gave rise to tuffs (light green). At the same time, the rift zone sank in fits and starts, resulting in the formation of a thick volcanic sequence (Kvenvik Greenstone), C). The basin was subsequently filled, initially by carbonate sediments (Storviknes dolomite) and finally by thick continental sandstones (Skoadduvarri sandstoene).

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Chapter 03 - p. 82d

Kvenvika greenstone with pillow structures. (Photo:S.Bergh)

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Chapter 03 - p. 82e

Storviknes dolomite with stromatolite structures. (Photo:S.Bergh)

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Chapter 03 - p. 83

The figure shows a scematic section illustrating the geological evolution in Nordaustlandet. Two unconformities separate three important stratigraphical units, the Helvetesflya Formation, the Svartrabbana Formation and the Murchisonfjorden Supergroup. An unconformable surface is an expression of a fundamental time interval - a milestone in the geological evolution of an area. It marks the end of a cycle of mountain chain formation and folding (F1 and F2 in the figure) followed by breakdown and erosion. The basal conglomerates record the onset of a new period of deposition of strata on an erosion surface. The youngest folds (F3) are Caledonian. The age of igneous rocks (granites and volcanic rocks) helps to time the various events.

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Chapter 03 - p. 85

The mountains north of Ersfjorden on Kvaløya, Troms, from Skamtinden in the west to Blåmannen and Orvasstinden in the east (right), consist of 1800 million-year-old granite. (Photo: K. Kullerud)

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Chapter 03 - p. 86

Geological map depicting the main features of the bedrock from Senja in the southwest to Vanna in the northeast. The Precambrian rocks along the coast underlie the Caledonian nappes that were thrust from the northwest. At Mauken, there is a tectonic window where Precambrian rocks show through the nappes.

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Chapter 03 - p. 87

Sandstone from Jøvik, Vanna. The sanstone, which is between 2400 and 2220 million years old, has crossbedding which shows that it was deposited as sand in a large, deep river, a delta or along a shore beside a sea or a large lake. (Photo: K. Kullerud)

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Chapter 03 - p. 88a

Photomicrograph of a thin section of the graphite ore from Senja; everything black is graphite.(Photo: H. Gautneb)

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Kap. 03 - s. 88b

The finished product, Silvershine from Skaland Graphite Mine. (Photo: H. Gautneb)

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Chapter 03 - p. 89

Geological map of Lofoten and Vesterålen.

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Chapter 03 - p. 90

Geological map showing the distribution of Precambrian rocks and Caledonian nappes in Nordland and western Troms. Archaean rocks occur furthest north. The basement windows in Nordland are mainly composed of Early Proterozoic granitic gneisses. Similar rocks also occur in Nord-Trøndelag.

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Chapter 03 - p. 92

The basement is mostly composed of crustal blocks. Geologists have referred to these blocks by a variety of terms over the years, including sectors and terranes. The amount of lateral and vertical movement that has taken place along the various shear zones that separate the blocks is not known. It is also uncertain how the various blocks have been situated in relation to one another 1600-1700 million years ago and subsequently.

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Chapter 03 - p. 93

Basement composed of Precambrian banded gneiss (in the foreground) beneath flat-lying Cambro-Silurian deposits (dark, in the background). The photograph is taken at Rognestranda in Bamble, Telemark. This locality is situated in an area in the counties of Vestfold and Telemark which was designated as a European geopark in autumn 2006, the first in the Nordic countries. The geoparks are approved by UNESCO and their intention is to display the most important geological environments on the Earth. (Photo: S. Dahlgren)

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Chapter 03 - p. 94a

A simplified geological map of south-western Scandinavia. The map focuses on the oldest rocks in the basement. Several parts of southern Norway (not differentiated on the map) have rocks which are at least as old.

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Chapter 03 - s. 94b

Ignimbrite from Flendalen in Trysil, scanned on a polished stone. This volcanic rock was formed by the welding together of dark pumice fragments and ash. (Photo: J. P. Nystuen)

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Chapter 03 - p. 95

Gneiss-forming processes deep in the crust.

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Chapter 03 - p. 95a

The photographs show three rocks that occur together in the Western Gneiss Region. The uppermost photograph shows a granulite with alternating dark and light bands formed during the Sveconorwegian orogeny. (Photo: A. Engvik)

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Chapter 03 - p. 95b

The dark layers in the middle photograph were transformed into eclogite and mixed with light-coloured quartzite at a depth of 60 km in the root of the Caledonian mountain chain. (Photo: A. Engvik)

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Chapter 03 - p. 95c

The lowermost photograph illustrates the banded gneiss that formed during the subsequent uplift, folding, flattening and metamorphism of the eclogite and quartzite. (Photo: A. Engvik)

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Chapter 03 - p. 96a

Mylonite from Mjøsa–Magnor mylonite zone east of Lake Mjøsa. (Photo: G. Viola)

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Chapter 03 - p. 96b

Metasedimentary rock composed of light-coloured layers of metasandstone alternating with darker layers of mica schist. The vertical beds were originally horizontal and were depostited in a marine basin near the Fennoscandian Shield 1600-1500 milion years ago. Photograph taken at Veme, west of Hønefoss. (Foto: Ø. Nordgulen)

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Chapter 03 - p. 97

Crustal factories along subduction zones. 

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Chapter 03 - p. 98

Geological map of parts of Telemark and Numedal. The stratified supracrustal rocks have been folded one or more times, which explains why the boundaries between the various rock types are  arcuate on the map. The youngest granites cut the boundaries between the older strata.

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Chapter 03 - p. 99

Rhyolite from the Rjukan Group north of Heddersvatn. The original layering is distinct. (Photo: S. Dahlgren)

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Chapter 03 - p. 100

V.M. Goldschmidt (right) and assistants in 1915. (NGUs Photo archive)

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 Chapter 03 - p. 101

Towering to a height of 1883 m a.s.l.,Gaustatoppen is the highest mountain in southeast Norway. The bare upper slopes of the mountain consist of hard quartzite that is poor in nutrients and is metamorphosed ripple-marked sandstone, originally deposited in basins close to sea level. (Photo:S.Dahlgren)

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Chapter 03 - p. 102

Quartzite with ripple marks formed on a sandy shore more than 1200–1300 million years ago. Vindsjåen,Telemark.(Photo:S.Dahlgren)

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Chapter 03 - p. 103

Erosion boundary (unconformity) between coarse conglomerate (Kalhovd Formation) with large, angular clasts (uppermost) and banded gneiss with severalt senerations of granite and pegmatite veins (below). (Photo: E.Sigmond)

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Chapter 03 - p. 104

Simplified map of southern Norway focusing on the Sveconorwegian mountain chain. The most important types of plutonic rocks are grouped according to their age. The blank areas on land indicate bedrock older than 1300 million years; e.g. older than the Sveconorwegian orogeny. Black lines indicate major faults.

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Chapter 03 - s. 105

The Monolith in the Vigeland Sculpture Park, Oslo. (Photo: T. Heldal)

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Chapter 03 - p. 106

From stone axes to kitchen benches: 9000 years of quarrying. (Photo: T. Heldal)

 

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Chapter 03 - p. 107a

Anorthosite landscape in Rogaland. (Photo:G.Meyer)

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Chapter 03 - p. 107b

The Rogaland Anorthosite Province consists of two large and several smaller anorthosite bodies. The western part of the Egersund-Ogna anorthosite consists entirely of anorthosite, but some light-coloured norite bodies occur further south-east. The Åna-Sira anorhosite consists mostly of light-coloured norite and anorthosite. In addition, there are small instrusions, mostly comprised of jotunite, mangerite and charnokite.

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Chapter 03 - p. 108a

Storeknuten sør for Helleland. Legg merke til den skråstilte skarpe grensen mellom bergarter med apatitt nederst til venstre, og bergarter uten apatittsom stikker opp som nakne knauser.(Foto:L.-P.Nilsson)

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Chapter 03 - p. 108b

The trough-shaped Bjerkreim–Sokndal intrusion near Bjerkreim is composed of six units which correspond to repeated injections of new magma from depth. Together, these units make up a several thousand-metre-thick succession in which economically valuable minerals like apatite and ilmeite are conentrated in specific layers. Younger jutonite dykes cut the layering in the intrusion. (Drawn by G.Meyer)

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Chapter 03 - p. 109

Opencast mine at Tellnes i Sokndal kommune, Rogaland, where Titania AS works ilmenite ore. (Photo: L.-P. Nilsson)

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Chapter 03 - p. 113

Map showing the general distribution of rocks in the Western Gneiss Religion. The Jotun Nappe Complex and other Caledonian nappes overlie the gneisses. (Map drawn by A.Solli)

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Chapter 03 - p. 114

Ålesund Church is built of variegated marble with some amphibolite, which often occurs with the marble. Here, the builders have returnend to the building practice used in the 12th-century stone churces in the northern part of west Norway. (Photo: I. Bryhni)

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Chapter 03 - p. 115

Inrusion breccia with angular blocks of the Precambrian bedrock carried up from depth in a dark plutonic rock nicely presented on a wave-washed shore at Farstad. (Photo: I. Bryhni)

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Chapter 03 - p. 116

The jagged peaks between Molladalen and Hjørundfjorden consists of charnockitic rocks, which have produced the dramatic, characteristic erosion forms. (Photo:I.Bryhni)

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Chapter 03 - p. 117

View from Litjegrønova (south of Lunde in Jølster) towards the mountains along Nordfjord, west of the Jostedalsbreen ice cap. In the foreground is deformed granite (now augen gneiss) with layers of aplite and a small pegmatite dyke. (Foto:I.Bryhni)

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Chapter 03 - p 118

Garnet pyroxenite with orhopyroxene (grey), clinopyroxene (green) and garnet (violet) from Nordøyane, Sunnmøre. The rock contains mineral grains that are partitioned from the high-pressure mineral, majoritic garnet. (Photo: I. Bryhni)

 

 

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