Principles of Physical Sedimentology PDF
Preview Principles of Physical Sedimentology
Principles of PHYSICAL SEDIMENTOLOGY TITLES OF RELATED INTEREST Petrology of the Sedimentary Rocks J. T. Greensmith Hardback (0 045 52029 1), paperback (0 045 520305), 288 pages A Dynamic Stratigraphy of the British Isles R. Anderton, P. H.B ridges, M. R. Leeder & B. W. Sellwood Paperback (041244510 7), 320 pages Ancient Sedimentary Environments R. C. Selley 3rd edn, Hardback (041227310 1), paperback (0 412 25730 0), 300 pages Sedimentary Structures 1. Collinson & D. Thompson 2nd edn, paperback (0 044 45172 5), 224 pages Deep Marine Environments K. Pickering, R. Hiscott & R . Hein Hardback (0 045 51122 5), paperback (0 044 45201 2),424 pages Geomorphological Techniques A. S. Goudie 2nd edn, paperback (0 044 45715 4), 570 pages Soil Geomorphology 1. Gerrard Hardback (0412441705), paperback (0 412 44180 2), 264 pages Quaternary Paleoclimatology R. Bradley Paperback (0 045 51068 7), 490 pages Principles of PHYSICAL SEDIMF,NTOLOGY J. R.L. ALLEN Department of Geology, University of Reading CHAPMAN & HALL London· Glasgow· New York· Tokyo· Melbourne· Madras Published by Chapman & Hall, 2-6 Boundary Row, London SE1 8HN Chapman & Hall, 2-6 Boundary Row, London SE1 8HN, UK Blackie Academic & Professional, Wester Cleddens Road, Bishopbriggs, Glasgow G64 2NZ, UK Chapman & Hall, 29 West 35th Street, New York NY1 0001, USA Chapman & Hall Japan, Thomson Publishing Japan, Hirakawacho Nemoto Building, 6F, 1-7-11 Hirakawa-cho, Chiyoda-ku, Tokyo 102, Japan Chapman & Hall Australia, Thomas Nelson Australia, 102 Dodds Street, South Melbourne, Victoria 3205, Australia Chapman & Hall India, R. Seshadri, 32 Second Main Road, CIT East, Madras 600 035, India First edition 1985 Reprinted 1992 © 1985 J.R.L. Allen Typeset 9 on 11 point Times by Mathematical Composition Setters Ltd, Salisbury, Wiltshire ISBN-13: 978-0-412-53090-6 e-ISBN-13: 978-1-4613-2545-1 DOl: 10.1007/978-1-4613-2545-1 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication Data Allen, John R. L. Principles of physical sedimentology. Includes bibliographies and indexes. 1. Sedimentation and deposition. 2. Hydraulic engineering. I. Title. QE571.A44 1985 551.3 85-6006 In memoriam Peter Allen Cover illustration Front (Upper) Pattern of streamlines round an equatorial section through a sphere in a Hele - Shaw cell. Front (lower) Current sorted and rounded debris formed from the coralline alga Lithothamnium, Connemara, Republic of Ireland. Back (upper) Large wave-related ripples in pebbly, shelly very coarse sand, Rocquaine Bay, Guernsey. Back (lower) Steeply climbing current ripple cross-lamination in vertical streamwise profile, Uppsala Esker, Sweden. Preface My aim in this book is simple. It is to set out in a logical apparatus is generally not required for the making of way what I believe is the minimum that the senior useful sedimentological experiments. Most of the equip undergraduate and beginning postgraduate student in ment needed for those I describe can be found in the kit the Earth sciences should nowadays know of general chen, bathroom or general laboratory , and the materials physics, in order to be able to understand (rather than most often required - sand, clay and flow-marking form merely a descriptive knowledge of) the smaller substances - are cheaply and widely available. As scale mechanically formed features of detrital sedi described, the experiments are for the most part purely ments. In a sense, this new book is a second edition of qualitative, but many can with only little modification my earlier Physical processes of sedimentation (1970), be made the subject of a rewarding quantitative exer which continues to attract readers and purchasers, inas cise. The reader is urged to tryout these experiments much as time has not caused me to change significantly and to think up additional ones. Experimentation the essence of my philosophy about the subject. Time should be as natural an activity and mode of enquiry for has, however, brought many welcome new practitioners a physical sedimentologist as the wielding of spade and to the discipline of sedimentology, thrown up a hammer. multitude of novel and exciting results and problems Although a quantitative treatment played an import and, on the personal side, materially altered and ant role in Physical processes of sedimentation, I very (hopefully) sharpened my appreciation of this field. I largely ducked in that book the issue of the derivation could not therefore have prepared a second edition in of equations, preferring to shelter behind such evasions the traditional sense but have instead written Principles as 'it can be shown that ... '. This I now believe was of physical sedimentology as an entirely new work. It is wrong and, while it might have painlessly provided him similar in scope to Physical processes of sedimentation or her with useful formulae, gave the reader no key to but, as my overriding aim is to give a well founded understanding or basis for attacking new situations account of general physical principles, the book in no from first principles. This nettle has been firmly grasped way attempts to be exhaustive as regards subject matter. in Principles of physical sedimentology, in which I have Thus there is no separate chapter on wind-related included an introductory chapter setting out the essence features and I have omitted altogether any discussion of of mechanics and fluid mechanics, and in which I de glacial phenomena. There is instead a new chapter on rived as many relationships as possible from first prin mass movements and their analysis, and I have placed ciples, writing out all but the most glaringly obvious considerable emphasis on, amongst other things, turbu steps; only in the case of certain essential aspects of lence and vortex phenomena, and on the mechanisms water waves are the mathematical requirements beyond and processes relating to muddy sediments. the level of this book. The user with a knowledge of Physical sedimentology is essentially an observational elementary algebra and calculus should therefore have science. It is important not only to look hard at and no difficulty in following my developments and, by think about sedimentary rocks and modern sediments example, should emerge confident that he or she can and processes in the field, but also to strengthen one's tackle new situations. The mathematics introduced is in intuitions and resolve one's uncertainties by frequently tended to do no more than to serve the requirements of making experiments in the laboratory. In the firm belief the particular physical problem; the reader should not that the user of this book will find them helpful, instruc allow himself or herself to be overawed by the symbols tive and worth the time to be spent on them, I have and equations, but should in turn make them his or her therefore described and in many cases illustrated a large servants. A word of caution is nonetheless due. The number of simple laboratory experiments. These are price of a mathematically simple analysis is with some further elaborated in a companion laboratory hand problems a degree of simplification that might horrify a book, Experiments in physical sedimentology, in which specialist researcher. I make no apology for this, so long many additional experiments will also be found. It can as the point is noted, as I believe it is better to see the not be too strongly emphasized, and especially to those truth indistinctly than not at all! It is best, of course, to readers beginning in sedimentology, that elaborate see the truth clearly and vividly. ix No book of this kind can be prepared without help of cases previously unpublished. My final scientific in many kinds from many people. I am deeply indebted to debtedness is to the many sedimentologists and re Mr Roger Jones of George Allen & Unwin Ltd, who searchers in other disciplines whose work I cannot encouraged me to bring out a revision of my earlier directly acknowledge, on account of the need to keep work, and who contributed materially, along with Mr the 'Readings' to a reasonable length. Mrs Audrey G. D. Palmer, to whom I am also grateful, to the Conner, Mrs Gillian Coward, Mrs Mary Downing and character of the present book. Dr Iaakov Karcz, Dr Mrs Dorothy West are warmly thanked for their endur Michael Leeder and Dr John Southard made many help ing patience and skilful typing. It is a pleasure to thank ful and important suggestions for the structure of the Mr J. L. Watkins for his help with the photographic book in its early stages, and to them I express my work and for his general advice on photographic gratitude. I am also greatly indebted to many friends matters. and colleagues who made suggestions for the improve ment of particular chapters or sections and who John R. L. Allen generously made available illustrative material, in some Reading x Contents Preface ix 4 Sliding, rolling, leaping and making sand waves 55 Tables xiii Notation xiv 4.1 Some field observations 55 4.2 Setting particles in motion 56 4.3 Defining the rate of sediment 1 Concepts and rules of the game 1 transport 58 1.1 Matter and influences 1 4.4 Physical implications of sediment 1.2 Flow rate 3 transport 59 4.5 Sediment transport modes 62 1.3 Law of continuity (conservation of mass) 5 4.6 Appearance and internal structure 1.4 Law of conservation of of bedforms 63 momentum 6 4.7 How do bedforms move? 67 1.5 Law of conservation of energy 7 4.8 Bedforms and flow conditions 71 1.6 Energy losses during fluid flow 10 4.9 Making wavy beds 74 1.7 Newton's laws of motion 11 4.10 A wave theory of bedforms 75 1.8 Fluid viscosity 12 Readings 78 1.9 Boundary layers 13 5 Winding down to the sea 81 1.10 Flow separation 15 5.1 Introduction 81 1.11 Applying the concepts and rules 16 5.2 Drag force and mean velocity of a Readings 19 river 83 2 Pressed down and running over 21 5.3 Energy and power of channelized 2.1 Introduction 21 currents 85 5.4 Why flow in a channel? 86 2.2 Particle composition and density 21 5.5 Width: depth ratio of river 2.3 How big is a particle? 22 channels 87 2.4 What form has a particle? 24 5.6 Long profiles of rivers 88 2.5 How close is a packing? 27 2.6 Kinds of packing 27 5.7 An experimental interlude 89 2.7 Voids 30 5.8 Flow in channel bends 91 2.8 Controls on packing 30 5.9 Sediment particles in channel bends 94 2.9 How steep is a heap? 35 2.10 Building houses on sand 36 5.10 Migration of channel bends 96 Readings 37 5.11 A model for river point-bar deposits 99 3 Sink or swim? 39 Readings 100 3.1 Two introductory experiments 39 6 Order in chaos 103 3.2 Settling of spherical particles 6.1 Introduction 103 arrayed in a stagnant fluid 40 6.2 Assessing turbulent flows - how 3.3 Settling and fluidization 44 to see and what to measure 104 3.4 Flow in porous media 44 6.3 Character of an ideal eddy 107 3.5 Controls on permeability 45 6.4 Streaks in the viscous sub layer 108 3.6 Settling of a solitary spherical 6.5 Streak bursting 113 particle in a stagnant fluid 46 6.6 Large eddies (macroturbulence) 115 3.7 Settling of a solitary non-spherical 6.7 Relation of small to large particle in a stagnant fluid 49 coherent structures 120 Readings 53 Readings 121 xi
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