Iceland

Thordarson Thor

Description

A concise and authoritative field guide to an exceptional natural laboratory, this title in the Classic Geology in Europe series is an essential companion for those visiting Iceland to observe the Earth in action. Rifting of the crust, volcanic eruptions and glacial activity are among a host of processes and features to be observed in this fascinating land. Nowhere else on Earth is the volcanic and tectonic architecture of seafloor rifts better exposed. Large icecaps and extensive river systems grind down the volcanic pile at rapid rates, dispersing and forming thick sequences of sediments. These formations are further modified by the pounding waves of the North Atlantic causing intriguing landforms that exhibit an intricate balance between the construction and erosion of land. Iceland is the only part of the North Atlantic Large Igneous Province that is still active and the only place on Earth where the construction of such provinces can be observed directly. As such, it is a window into the formation of proto-continents early in the Earths history. For the past seven million years Iceland has been situated at the boundary of major air and ocean masses and has consequently been exposed to extreme climate changes. The effects of the climate on the rock-forming processes are clearly illustrated by diverse sedimentary and volcanic successions and by the wide range of volcanic landforms formed in sub-aqueous to sub-aerial environments; each succession reflecting the characteristics of internal and external processes.Icelandic culture cannot be fully comprehended without understanding its geology. Thus the book will interest not only student, amateur and professional geologists but also others attracted by the natural environment and seeking a deeper understanding of what makes Iceland the unique place that it is.

Sujets

• Sciences et techniques
• Iceland
• Islande

Informations

• Publié par: Dunedin Academic Press
• Date de parution: 01 février 2022
• Nombre de lectures: 0
• EAN13: 9781780466484
• Langue: English
• Poids de l'ouvrage: 7 Mo

Extrait

Classic Geology in Europe 3
Iceland
Third Edition
Thor Thordarson
Faculty of Earth Sciences, University of Iceland
Ármann Höskuldsson
Institute of Earth Sciences, University of Iceland
Contents
Preface
Acknowledgements
Introduction
Travel in Iceland ; Pronunciation
The geology of Iceland
Introduction ; Geological setting: a global perspective ; Geological framework ; Volcanism ; Neogene, Quaternary, Holocene
The southwest
General overview ; Greater Reykjavík ; Reykjanes–Grindavík–Kleifarvatn
The south
General overview ; Þingvellir–Geysir–Gullfoss ; Hreppar–Þjórsárdalur–Hekla
Vestmannaeyjar (the Westman Islands)
General overview ; Heimaey ; The 1963–7 Surtsey eruption
The central south
General overview ; Eyjafjallajökull and Mýrdalur ; The Fire Districts
The southeast and east
General overview ; Suðursveit–Lón–Álftafjörður ; The eastern fjords
The northeast
General overview ; Jökulsá–Tjörnes ; Krafla–Mývatn
The north and northwest
General overview ; Fnjóskadalur to Skagi
The west
Snæfellsnes–Borgarfjörður – volcanic zones and rift jumps
The Highlands
General considerations ; Askja–Kverkfjöll ; Landmannalaugar–Veiðivötn
Addendum
Glossary
Bibliography
Index
GPS coordinates
Preface to the Third Edition
Iceland is a ‘wonderland’ when it comes to earth sciences, and in a class with other geological wonders on Earth. Mother Earth is very much alive in Iceland, continually working the land, and in doing so, keeping its inhabitants on notice regarding the might of the natural forces. It is an integral part of the Icelandic psyche and essential for a full appreciation of the country’s history. The purpose of this book is to present the basics of Icelandic geology and its influence on Icelandic culture.
In writing a book such as this, authors rely on innumerable written sources representing countless hours of work by a large group of researchers. However, it is impractical to include hundreds of direct citations to individual works in a text of this nature, as it would make it very difficult for the introductory reader. Nevertheless, we would like to extend our gratitude to the scientists whose work has made the writing of this book possible, and we dedicate it to them. Some of these contributions are listed in the Bibliography, and acknowledgements for illustrations borrowed with permission from other texts are listed overleaf.
We have kept the general framework of the second edition. In addition to some revision and correction of the original text, we have, in Chapter 10 , added a new section on the 2014–15 eruption at Holuhraun, along with adding and updating the figures and tables where appropriate. One of the main changes in this edition is that regional geological maps are now superimposed on a digital elevation model, providing a 3D perspective to those figures. Detailed bathymetry has been added to the map of the Vestmannaeyjar archipelago ( Chapter 4 ). Finally, we thank Anthony Kinahan and all those working with Dunedin Academic Press for their patience and support in the making of this third edition.
Thor Thordarson Ármann Höskuldsson March 2020
Publisher’s Note:
This third edition of Iceland was ready for press in March 2021 when the 2021 Fagradalsfjall eruption occurred. As the Covid-19 Pandemic was then preventing students from travelling on field trips to Iceland, the authors agreed to delay publication so that they could include some coverage of 2021’s eruption in the new edition. As international travel resumes, it is evident that there will be much to learn from the 2021 Fagradalsfjall eruption, which is already the longest-lasting eruption in Iceland in the 21st century. However, at this early stage, information is incomplete. A brief section on the 2021 Fagradalsfjall eruption has been added to the book at page 239 as an Addendum.
Acknowledgements
The authors would like to acknowledge the following sources for permission to use copyright material in the preparation of the illustrations, all of which have been modified. The full bibliographic details are in the Bibliography ( pp. 248 – 250 ). All other illustrations are the work of the authors themselves.
Figure Source 1.1 Saunders et al. (1997) 1.2 Sæmundsson (1979) 1.3 Jóhannesson (1980) 1.4 Steinþórsson (1981) 1.5 Jóhannesson & Sæmundsson (1998) 1.6 Guðmundsson (1995) 1.7a Alfreð Jónasson, courtesy of Sólarfilma 1.7c Marta Bergman & Bergsteinn Gizurarson 1.9d Self et al. (1998) 1.10b Lockwood & Lipman (1980) 1.10d McPhie et al. (1993) 1.11 Thordarson and Höskuldson (2008) 1.13c Ágúst Guðmundsson 1.15b Ágúst Guðmundsson 1.15c John Maclennan 1.16 Sæmundsson (1979) 1.17a Einarsson (1991) 1.20 Oddur Sigurðsson 1.21 Geirsdóttir & Eiríksson (1994a) 1.22 Walker (1966) 2.1 Jóhannesson & Sæmundsson (1998) 2.2 Geirsdóttir & Eiríksson (1994b) 2.3 Geirsdóttir & Eiríksson (1994b) 2.6 Kjartansson (1973) 2.7c Sigurgeirsson (1995) 2.8 Jónsson (1978) 3.1a Jóhannesson & Sæmundsson (1998) 3.1b Einarsson & Björnsson (1979) 3.2 Einarsson (1991) 3.3 Sæmundsson (1992) 3.4b Einarsson (1991) 3.7 Larsen & Thorarinsson (1977) and Larsen et al. (1999) 4.1 Jakobsson (1968) 5.1 Jóhannesson & Sæmundsson (1998) 5.2 Magnús T. Guðmundsson 5.4 Magnús T. Guðmundsson 5.5b Jón Kjartan Björnsson 5.6 Steinþórsson (1966) 5.8 Oddur Sigurðsson 5.9 Larsen (2000) 5.10 Larsen (2000) 5.11 Larsen (2010) 5.12 Thordarson et al (2001) 5.13a Larsen (2000) 5.14a , b Thordarson & Self (2001) 5.15 Thordarson & Self (2001) 5.17 Tordarson & Larsen (2007) 5.18 Magnús T. Guðmundsson 5.19 Magnús T. Guðmundsson 5.21a , b Kári Kristjánsson 5.21c , d Magnús T. Guðmundsson 5.22 Thorarinsson (1958) 5.23b , c Thorarinsson (1958) 6.1 Jóhannesson & Sæmundsson (1998) 6.2 Walker (1963) & Martin et al (2011) 6.5 Jónsson (1988) 6.7a Blake (1966) 6.8 Oddur Sigurðson 6.9 Walker (1958) 6.10a Walker (1963) 6.13 Walker (1962) 6.14 Walker (1962) 6.15 Walker (1966) 7.1 Jóhannesson & Sæmundsson (1998) 7.4 Einarsson (1991) 7.7 Sæmundsson (1991) 7.8 Sæmundsson (1991) 7.12 Sæmundsson (1991) 7.13 Sæmundsson (1991) 8.1 Jóhannesson & Sæmundsson (1998) 8.2 Norðdahl & Hafliðason (1992) 9.1 Jóhannesson & Sæmundsson (1998) 9.2 Jóhannesson (1980) 9.4 Björn Harðarson (1993) 9.6 Oddur Sigurðsson 9.7 Jóhannesson (1980) 9.8 Einarsson (1991) 10.3 Mohn (1877) 10.4 Hartley and Thordarson (2012) 10.6 Sigbjarnason (1996) 10.8 Gunnarsson (1987) 10.9 Larsen (1984)
Introduction
Iceland is one of the very few places where we can directly observe the Earth’s growth processes in action. We all are aware of two geological fundamentals: the tangible materials that we walk on and the sometimes intangible processes that operate on our surroundings. The materials (excluding living organisms) are the rocks that make up the solid crust or the outermost shell of the Earth, and the processes represent the forces that construct and erode these crustal rocks and thus shape the landscape that we have before us. The processes that operate at or near the Earth’s surface are generally categorized as external, whereas those that are at work deep below the surface, or result from such activities, are called internal.
Iceland is an exceptional natural laboratory where almost all of the principal geological processes can be observed and it is an ideal setting for laymen, as well as professionals, to witness how Mother Nature operates. Unusually high rates of volcanic activity and dynamic fault movements, coupled with rapid erosion and efficient transport and deposition of sediment, make Iceland a diverse environment where constructive processes outweigh destructive ones. Nowhere on Earth is the architecture of the spreading sea floor better exposed, where different patterns of fault lines and fault movements, along with chains of volcanoes, characterize the parts of Iceland interpreted as the boundary between the Eurasian and American plates.
Large icecaps and extensive river systems rapidly grind down the volcanic pile, dispersing vast amounts of debris from the highlands to the lowlands to form thick sequences of glacial, fluvial and lacustrine sediments. Along the seashore these formations are further modified by the pounding waves of the North Atlantic, where the often spectacular landforms exhibit an intricate balance between land construction and erosion.
Over the past seven million years Iceland has been situated at a boundary of major air and ocean masses, and consequently has been exposed to extreme climatic changes. The rocks in Iceland clearly reflect this fluctuating climate. The dynamic interplay between constructive and destructive geological processes has resulted in the juxtaposition of volcanic and sedimentary rocks. Dramatic swings in the climate over the past seven million years are clearly illustrated by the occurrence of diverse rock types in alternating volcanic and sedimentary successions. These changes have also resulted in a wide range of volcanic structures, because the eruptions occurred in environments ranging from subaqueous through subaerial to subglacial ( Fig. 0.1 ). Consequently, each rock formation reflects the flavour particular to the builders – the spectrum of internal and external processes that moulded Iceland into its current shape.

Figure 0.1 Hekla in South Iceland, the queen of icelandic volcanoes, viewed from southwest.
Iceland is the youngest part of a much larger volcanic province that extends from Scotland to Greenland. It is also the only part of the province that is still active and possibly the only place on Earth where the processes involved in the construction of this type of volcanic province can be observed directly. Furthermore, it provides a window into continent formation as it was early in Earth’s history, because such continents are likely to have been produced by volcanism of a nature similar to that found in Iceland.
There are various ways one could organize a book of this kind, but we have chosen a format that follows an excur