The Nature of the Stratigraphical Record

164 Pages·1993·7.45 MB·English

by  Derek V. Ager

The Nature of the
Stratigraphical Record
Third Edition
DEREK V. AGER
Emeritus Professor of Geology, U11iversity College of S1.<>n11sea,
Unit1ersily of Wales, UK
JOHN WILEY & SONS
Chiclw!-ill't' · Nt'\\ 1 ork · Bri...,banl' · Toronto · Singapore
Copyright © 1973, 1981, 1993 by D. V. Ager
First published in Great Britain 1973 by The Macmillan Press Ltd, and in the
USA by Halsted Press, a Division of John Wiley & Sons, Inc.
Second edition 1981.
Third edition published ·1993 by john Wiley & Sons Ltd,
Baffins Lane, Chichester,
West Sussex P019 1UD, England
All rights reserved.
No part of this book may be reproduced by any means,
or transmitted, or translated into a machine language
without the written permission of the publisher.
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Library of Congress Cataloging-in-Publication Data
Ager, D. V. (Derek Victor)
The nature of the stratigraphical record I Derek V. Ager. - 3rd
ed.
p. em.
Includes bibliographical references and index.
ISBN 0-47L-93808-4 (paper)
1. Geology, Stratigraphic. I. Title.
QE651.A37 1993
551.7-dc2.0 92-30173
CIP
British Librnry Cataloguing in Publication Data
A catalogue record for this book is available from the British I ibrary
ISBN 0-471-93808-4
rypt'~Ct Ill II 11pt Palatino by f)obbtc Tvpc.,l'lling I td, 1,1\'l<;hl\~ lh'\'On.
Pnnll'd .111d hnund in Cn·.lt Hrit,tin b, tliddlt•s I td { olllldlold ollld ~ Ill); ... I' llll
For
Kitty and Martin
:
Contents
Preface to the First Edition ix
Preface to the Second Edition xi
Preface to the Third Edition xiii
I. The Persistence of Facies 1
26
2. The Fleeting Fossil
More Gaps than Record 43
4. Catastrophic Stratigraphy 55
c;, C.ltastrophic Uniformitarianism 73
6 The Process of Sedimentation 86
7. Mt11 xisl Stratigraphy and the Golden Spike 97
H 'Jiw i\ature of the Control 112
145
/rrdn

Preface to the First Edition
I his is not a textbook or a research treatise. It is-Ilike to think
·'n
'ideas book'. It is a commentary on the general pattern of
e.11th history which I hope will be stimulating, if perhaps
provocatively so, to all those concerned with geology as a whole
.1ther than as a loose agglomeration of separated specialities.
1
I wrote it because I had to, because the ideas it contains have
bl•c.:>n fermenting in my brain for years and I had to write them
lown before 1 become completely intoxicated. 1n a sense, it is
-triltigraphy looked at by a non-stratigrapher. I have always used
1i11d taught stratigraphy rather than actually made it, but I can
offer the excuse that the non-combatant usually has a clearer
pkture of the battle than the soldiers actually engaged in the
l1ghting. It seems to me that the conclusions contained in this
book are inescapable, if one is not too involved in the minutiae
l'' stratigraphical correlation actually to see them.
No doubt I shall be criticised for some of my generalisations,
bt~l I am unrepentant. It is sad if some of my details are wrong
over-simplified, but 1 am obstinate enough to maintain that
lll
tiH· general principles, in which I am chiefly interested, are right.
I h.1ve tried, as far as possible, to use examples which I have
'-t't'll for myself and which have impressed me. If the Chalk and
tl11• Wenlock Limestone also occur in Ruritania, then I am
dPiightcd to hear it, but I have not seen them there, so it has
11111 n·~Jslen•d in my simple mind. My motto in this connection
as th.1t of Llw great )oachirn Barrande-'C'est ce que j'ai vu'.
I tiT tlw s.tml' Tl'•ls<m, I h.wc not made great use of the literature.
ln1 lhv most p.lrl llt.lVI.' onlv n•fp1 r('d to book<; nnd papers when
.,\,1111' :;.llhst.lllli.tlitlll st•t•ms lt•lw nl•t•dt•d lor c1 n•rt,1in point. I have
x Preface to the First Edition
also made particular use of work by myself or by friends, where
I have had the opportunity to discuss the matter or to see it for
myself. For the sake of readability, I have omitted most direct
references from the text. I apologise to the authors concerned,
but a selection of the more relevant papers are listed in an
annotated bibliography at the end of each chapter. These are not
intended to be exhaustive.
The one great hope I have for this book is that it will stimulate
thought and argument, even rage. I think our science would be
a lot healthier if we took less for granted. It may be said that
I do not relate my thoughts sufficiently to all the exciting new
ideas of sea-floor spreading and plate tectonics that have
revolutionised our thinking in the last few years. But really these
ideas, exdting though they are, do not help very much. My
stratigraphical enigmas remain the same wherever the plates are
sailing round the earth. In some cases, rearrangements of the
continents merely make my problems more difficult. At times
I almost feel more willing to put the blame on flying saucers than
on floating plates.
I would like to thank my former colleague Dr Peigi Wallace
very sincerely for her careful and critical reading of the
manuscript and for our many useful discussions over the years.
Though we agree on the general principles discussed here, she
is in no way responsible for my errors and excesses. Nor are my
former colleagues, Professor Gilbert Kelling and Professor Mike
Brooks, both of whom very kindly read and criticised this text.
I am very grateful to Mary Pugh and John Uzzell Edwards for
drawing the figures, to Stan Osbmne and Christine Nicholls for
printing my photographs, and to Mrs J. Nuttall, Miss M. Davies
and Mrs J. Waring for typing the manuscript with great care.
Finally, let me say a word to those who think that science in
general and stratigraphy in particular are solemn matters that
should be h·eated at all times with respect: you had better not
read this book; you will find it too light-hearted.
Derek Ager
Swa11sea, 1972
Preface to the Second Edition
Reactions to the first edition of this book ranged from near ecstasy
to something approaching scorn. Fortunately the former were
\'cry much in the majority and nothing I have seen, heard or
read since has persuaded me to change my somewhat extreme
u~ws; in fact I have been encouraged in my prejudices.
E,·erywhere I go I see rapid deposition, frequent breaks and
incredible persistence. I write this as I return from a visit to Kenya
" here I saw between Mombasa and Malindi the (often oolitic)
Bajocian limestones forming an escarpment just like my beloved
( otswolds, the chief difference being that the stately beeches
replaced by massive baobabs. In neighbouring Tanzania I
.tl'l'
s.n, repeated rushes of conglomerate in the Upper Jurassic along
cuntemporaneous fault lines.
I have received shoals of reprints about storm deposits up and
down the column all round the world, I have been invited to
IMif a-dozen conferences on variations of the theme 'the
rmportance of the rare event'.
Mv one serious critic concentrated on my apparent disregard
for generations of careful stratigraphical nit-picking. No one who
wnrks on the European Jurassic as I do can be unaware of the
nirl'ltes and necessities for what may be called 'microstratigraphy'.
In f.Kl I would emphasise what it has shown us about the
\.ltmplcxilies of the seemingly most straightforward parts of the
~!J,lligr,,phical rewrd But I must say again that we should step
b,wk .1t times .Hld M'C the full width of the canvas. That is what
I h.t\'l' trwd to do
In I 11 j., "('cnnd t>d it ion I h,Wl' corl'l'i lt>d a few of the errors, I
h.1\ t' inlr(lduu•d lurtlwr .1nd lwllt•t t''•lmpll'!' that h.wP cnmc to