Introducing Geology: A Guide to the World of Rocks

145 Pages·2018·39.433 MB·English

by  Graham Park

Introducing Geology
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Other Titles in this Series:
Introducing Astronomy
Introducing Geomorphology
Introducing Meteorology ~ A Guide to the Weather
Introducing Metamorphism
Introducing Mineralogy
Introducing Natural Resources
Introducing Oceanography
Introducing Palaeontology ~ A Guide to Ancient Life
Introducing Sedimentology
Introducing Stratigraphy
Introducing Tectonics, Rock Structures and Mountain Belts
Introducing the Planets and their Moons
Introducing Volcanology ~ A Guide to Hot Rocks
For further details of these and other Dunedin
Earth and Environmental Sciences titles see
www.dunedinacademicpress.co.uk
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Introducing
Geology
A Guide to the World of Rocks
THIRD EDITION
Graham Park
DUNEDIN
EDINBURGH  LONDON
iii
Published by
Dunedin Academic Press Ltd
www.dunedinacademicpress.co.uk
Head Office
Hudson House, 8 Albany Street
Edinburgh, EH1 3QB
Scotland
ISBN
978-1-78046-075-8 (Paperback)
978-1-78046-596-8 (ePub)
978-1-78046-597-5 (Kindle)
© 2018 Graham Park
First Edition 2006
Second Edition 2010
Third Edition 2019
The right of Graham Park to be identified as the author of this book has been asserted by
him in accordance with sections 77 & 78 of the Copyright, Designs and Patents Act 1988
All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any
means or stored in any retrieval system of any nature without prior written permission,
except for fair dealing under the Copyright, Designs and Patents Act 1988 or in accordance
with a licence issued by the Copyright Licensing Society in respect of photocopying or
reprographic reproduction. Full acknowledgment as to author, publisher and source must
be given. Application for permission for any other use of copyright material should be
made in writing to the publisher.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Design, pre-press production and typesetting
by Makar Publishing Production, Edinburgh
Printed and bound in Poland by Hussar Books
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Contents
Acknowledgements vi
List of tables and illustrations vii
Sourced illustrations ix
Preface: A world of rock x
1 Crystals, minerals and gemstones 1
2 Volcanoes and melted rock 9
3 Shaping the land 21
4 Mud, sand and other deposits 34
5 Moving continents and making mountains 42
6 Earthquakes and faults 55
7 Squeezing and stretching – rock deformation 65
8 Geological time and the age of the Earth 71
9 Fossils – a history of life 77
10 Turning the pages – Earth history 91
11 Geology and industry 105
Glossary 114
Further Reading 134
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Acknowledgements
I am indebted to Mrs Anne Shelley of the Orcadian Stone Company, Golspie, Sutherland, for
allowing me to photograph some of the excellent specimens of fossils and minerals in her
geological museum. My thanks are also due to Anne Morton of Dunedin Academic Press and an
anonymous reviewer of the draft of the first edition for their numerous helpful suggestions, and
to Professor Charles Holland of Trinity College, Dublin for his careful review of chapters 9 and 10.
The second edition has benefited from a number of helpful suggestions for improvement
from various reviewers of the first edition. I am grateful in particular to John Winchester, who
pointed out a number of mistakes and drew my attention to the revised geological timescale.
Any remaining inadequacies in this book are entirely the author’s responsibility.
Finally I wish to thank my wife Sylvia for her constant support and encouragement, and as a
non-geologist, for ‘test driving’ the first draft.
The following sources of data were particularly useful.
Duff, P. McL. D., Holmes’ Principles of Physical Geology, 4th edition, Chapman & Hall,
London, 1993.
Gradstein, F. M., Ogg, J. G. & Smith, A. G., A Geologic Time Scale, Cambridge University
Press, 2005.
Keary, P. (ed.), The Encyclopedia of the Solid Earth Sciences, Blackwell, Oxford, 1993.
Lambert, D., The Cambridge Field Guide to Prehistoric Life, Cambridge University Press,
1985.
Stanley, S. M., Exploring Earth and Life through Time, Freeman, New York, 1993.
Note to the third edition
I have taken the opportunity to thoroughly revise the text and improve many of the line drawings,
with greater use of colour, taking into account the many helpful suggestions made by reviewers.
Some of the photographs have been exchanged for better versions, and a number of others
added. Graham Park, July 2018.
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List of tables and illustrations
Table 2.1 Main types of igneous rock. 18
Table 4.1 Some common types of sedimentary rock. 36
Table 6.1 Measuring earthquake effects: Mercalli and Richter scales. 56
Table 8.1 The stratigraphic column. 73
Table 9.1 The family tree of man. 79
Figure 1.1 Crystal structure. 2
Figure 1.2 A, quartz crystal; B, calcite crystal; C, geode; D, muscovite mica. 3
Figure 1.3 A, gypsum; B, fluorspar (fluorite). 5
Figure 1.4 A, hematite; B, pyrite; C, malachite; D, azurite; E, galena. 6
Figure 1.5 A, agate; B, garnet 7
Figure 2.1 Vulcanicity: A, erupting volcano; B, ropy lava; C, pyroclastic flow. 10
Figure 2.2 A, volcanic breccia; B, geyser. 11
Figure 2.3 A, igneous dyke; B, basalt pillow lava. 12
Figure 2.4 Magma chambers and channels: types of igneous intrusion. 14
Figure 2.5 A, granite; B, basalt; C, dolerite dyke; D, photomicrograph of gabbro 15
Figure 2.6 Main regions of the Earth’s interior. 17
Figure 2.7 Origin of oceanic basaltic lavas. 19
Figure 3.1 Erosion: granite tor. 22
Figure 3.2 Erosion: A, effects of erosion on soft beach sand; B, debris apron. 23
Figure 3.3 River systems: A, potholes; B, river meanders. 24
Figure 3.4 Effects of rejuvenation on a river profile. 26
Figure 3.5 Coastal effects: A, raised beach; B, ripple marks on beach sand; C,
mud cracks. 27
Figure 3.6 Desert erosion: A, canyon; B, mesa and buttes. 29
Figure 3.7 Glaciation: A, valley glacier; B, the end of the Briksdal Glacier;
C, crevasse. 31
Figure 3.8 Glaciation: A, glacial erratic; B, glaciated corrie; C, the Matterhorn. 32
Figure 4.1 Sedimentary rock layering: A, bedding; B, formations, Grand Canyon. 35
Figure 4.2 Clastic sedimentary rock: pebbles in coarse sandstone. 37
Figure 4.3 Sedimentary structures: A, cross-bedding; B, mud cracks; C, load
casts in greywacke. 39
Figure 4.4 A, boulder tillite; B, red and green bedded cherts. 41
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List of tables and illustrations
Figure 5.1 Gondwana. 42
Figure 5.2 Climatic zones of Pangaea. 43
Figure 5.3 200 million-year-old north pole positions. 43
Figure 5.4 Main topographic features of continents and oceans. 45
Figure 5.5 The ‘conveyor-belt’ model. 46
Figure 5.6 Pattern of recent earthquake and volcanic activity. 47
Figure 5.7 The plates and their boundaries. 48
Figure 5.8 The Red Sea–Gulf of Aden–African Rift system. 50
Figure 5.9 Subduction and collision. 51
Figure 5.10 Mechanisms for plate motion. 53
Figure 5.11 A, Iceland hot-spot; B, model of a plume. 54
Figure 6.1 Earthquake damage. 55
Figure 6.2 Earthquake waves: recording, wave paths and location. 59
Figure 6.3 Types of fault: normal, reverse and wrench. 60
Figure 6.4 Thrust faults. 61
Figure 6.5 Normal fault. 62
Figure 6.6 Extension by faulting. 63
Figure 6.7 Strike-slip faulting. 63
Figure 6.8 Columnar jointing, Staffa. 64
Figure 7.1 Fold shapes. 66
Figure 7.2 A, folding associated with faulting; B, flow folds. 67
Figure 7.3 Rock fabric. 68
Figure 7.4 Fabric: A, foliation; B, cleavage; C, lineation; D, shear zone. 69
Figure 7.5 Transition from fault to shear zone: section through the crust. 70
Figure 8.1 Hutton’s unconformity. 72
Figure 9.1 Evolution of the graptolites. 81
Figure 9.2 Evolution of the cephalopods. 81
Figure 9.3 A, goniatite; B, trilobite. 83
Figure 9.4 A, coral; B, brachiopod Terebratulina; C, echinoid Clypeaster; D, ammonite. 85
Figure 9.5 A, Jurassic fish; B, Tyrannosaurus rex; C, Archaeopteryx; D, fly and
spider in amber. 87
Figure 10.1 Early Proterozoic supercontinent. 94
Figure 10.2 Rodinia: a mid-Proterozoic supercontinent. 95
Figure 10.3 Pannotia: a late Proterozoic supercontinent. 96
Figure 10.4 Mid-Palaeozoic reconstruction of the continents. 97
Figure 10.5 The assembly of Pangaea. 99
Figure 10.6 The break-up of Pangaea. 100
Figure 11.1 Structural traps for oil and gas. 106
Figure 11.2 Oil production platform. 107
Figure 11.3 Artesian aquifer. 113
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Sourced illustrations
The following illustrations are reproduced by permission: British Geological Survey. ©NERC. All rights
reserved. IPR/73-34C, 122-06CT: Figures 1.2D, 2.1A, C, 2.5A, D, 3.1, 3.3B, 3.5A, 3.7A, 3.8A, B, 8.1, 9.4A, B, C,
and 9.5D; ©Science Photo Library: Figure 9.5B, C; Shutterstock: 1.2C, 1.3B, 1.4D, E, 1.5A, 2.2B, 3,2B, 3.6B,
3.8C, 6.1, 9.5A, 11.2.
The following illustrations have been adapted from published sources:
Figure 2.6: Hamblin, W.K. 1989. The Earth’s dynamic systems, 5th edition. Macmillan, New York.
Figure 2.7: Bott, M.P. 1982. The interior of the Earth, 2nd edition, Edward Arnold, London.
Figure 5.1, 5.2: Hamblin, W.K. 1989. The Earth’s dynamic systems, 5th edition. Macmillan, New York.
Figure 5.3: McElhinny, N.W. 1973. Palaeomagnetism and plate tectonics, Cambridge University Press.
Figure 5.4: Wyllie, P.J. 1976. The way the Earth works. Wiley, New York.
Figure 5.6: Chadwick, P. 1962. Mountain-building hypotheses. In: S.K. Runkorn (ed) Continental drift.
Academic Press, New York, London (seismicity); galleryhip.com (volcanoes) via Wikimedia commons.
Figure 5.7: Vine, F.J. and Hess, H.H. 1970. In: The Sea, v4. Wiley, New York.
Figure 5.8: weebly.com/somali plate via Wikimedia Commons.
Figure 5.11A: Saemundsson, K. 1974. Evolution of the axial rifting zone in northern Iceland. Bulletin of the
Geological Society of America, 85, 495–504.
Figure 6.4C: Elliott, D. and Johnstone, M.R.W. 1980. Structural evolution in the northern part of the Moine
thrust zone. Transactions of the Royal Society of Edinburgh: Earth Sciences, 71, 69–96.
Figure 6.6B: Lister, G.S. & Davis, G.A. 1989. The origin of metamorphic core complexes. Journal of
Structural Geology, 11, 65–94.
Figure 7.5: Ramsay, J.G. 1980. Shear geometry: a review. Journal of Structural Geology, 2, 83 99.
Figure 10.1: Buchan, K.L., Mertanen, S., Park, R.G., Pesonen, L.J., Elming, S.A., Abrahamsen, A. & Bylund,
G. 2000. Comparing the drift of Laurentia and Baltica in the Proterozoic: the importance of key
palaeomagnetic poles. Tectonophysics, 319, 167–98.
Figures 10.2, 10.3, 10.4: Dalziel, I.W.D. 1997. Neoproterozoic-Palaeozoic geography and tectonics: review,
hypothesis, environmental speculation. Geological Society of America Bulletin, 109, 1, 16–42.
Figure 10.5: Matte, P. 1986. Tectonics and plate tectonics model for the Variscan belt of Europe.
Tectonophysics, 126, 329–74.
Figures 10.5, 10.6: : Torsvik, T.H. and Cox, L.R.M. 2017. Earth history and palaeogeography. Cambridge
University Press.

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