Recent Earth History

140 Pages·1973·15.034 MB·English

by  Claudio Vita-Finzi (auth.)

RECENT EARTH HISTORY
RECENT EAR TH
HISTORY
Claudio Vita-Finzi
University College London
Macmillan Education
© Claudio Vita-Finzi 1973
Softcover reprint ofthe hardcover 1st edition 1973 978-0-333-15027-6
All rights reserved. No part of this publication may be
reproduced or transmitted, in any form or by any means,
without permission.
First published 1973 by
THE MACMILLAN PRESS LTD
London and Basingstoke
Associated companies in New York Dublin
Melbourne Johannesburg and Madras
ISBN 978-0-333-15136-5 ISBN 978-1-349-86181-1 (eBook)
DOI 1O.l 007/978-1-349-86181-1
The paperback edition of this book is sold subject to the condition
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hired out, or otherwise circulated without the publisher's prior
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To P
Contents
Prefaee Xl
1 Introduetion 1
2 Stratigraphical earth history 5
3 Chronometrie age 17
4 Subdividing the reeord 35
5 Ancient shorelines 49
6 Cores and boreholes 65
7 River deposits 79
8 Cave infills 95
9 Cases and laws 105
Notes 113
Bibliography 123
Index 135
Acknowledgments
I am greatly indebted to the following, as well as to the authors con
cerned, for permission to use illustrative and other material: W. H.
Freeman and Co. (figure 2); The Geological Society of America
(figures 4, 9B, 11 and 12D); The University of Colorado (figure 5);
Almqvist and Wiksell Förlag AB (figure 6); The M.I.T. Press (figure
8); American Journal oi Science (figure 9A); Botaniska Notiser
(figure 10); The American Association for the Advancement of
Science (figure 11A and 13: Copyright 1968 and 1964 by the Ameri
can Association for the Advancement of Science) ; UNESCO (figure
llA); Longman Group Ltd (figure 12A); Quaternaria (figure 12B);
Macmillan (Journals) Ltd (figure 12C); The University of Chicago
Press (figure HC: Copyright 1955 by the University of Chicago);
Jonathan Cape Ltd (figure 14B); Marine Technology Journal (figure
15); Gebrüder Borntraeger (figure 16B); The University of Texas
Press (figure 17A); Faber & Faber Ltd (figure 18); The American
Association of Petroleum Geologists (extracts from the Code of
Stratigraphie Nomenclature in chapter 2 and 7).
Preface
This book was conceived as an elephantine compendium and has
emerged as a polemical mouse. My original intention was to write
an account of the physical changes undergone by the earth during
Holocene (or Postglacial) times, in the fonn of a stratigraphical
narrative embellished by a few key radiocarbon and historical dates.
But, as the work proceeded, I became convinced that dating, rather
than serve as an adjunct to stratigraphy, deserved to replace it as
the basis of chronology. Some will find this view self-evident, but
as it did not appear to be widely held by geologists and prehis
torians I decided to argue its merits using the last 20 000 years as
the main source of illustrations.
It may seem fraudulent to base the general case on apart of
the record which is exceptionally weIl endowed with quantitative
dates. But my aim is simply to demonstrate the benefits of a par
ticular approach: dentifrice advertisements do not usually show
toothless gums. Moreover, if the proposals are at present difficult
to implement throughout the earth's history it does not follow that
the underlying principles are fallacious. In any case many of the
recent dates al ready on hand have been little exploited, whereas
much of what is preached here is already common practice among
students of the Precambrian, if at times only because a lack of
fossils or of stratification debars them from more conventional
methods of subdiving their material.
As the book presents a very definite point of view it may do less
than justice to studies which do not confonn. The inclusion of
detailed references and notes to each chapter will partly atone for
this; nevertheless the intention has been to make the text self
sufficient. The first three chapters deal with the problems of dating
and correlation in general. Chapters 4 to 8 consider how quantita
tive dating can help in the study of selected sequences, whether
through the 'mete ring' of local changes or the construction of
xii PREFACE
regional time-planes and time-lines. The final chapter attempts to
show that such procedures lead on to productive generalisation.
I should add that, although physical geology dominates the case
studies (with prehistory in second place), I have tried to make the
book palatable to readers primarily concerned with other aspects
of terrestrial chronology.
What originality there is in the pages that follow sterns from
studies I was enabled to carry out by the generous and tolerant
support of the Nuffield Foundation. I am also indebted to John
Adams, Eric Higgs, David Krinsley, John Pfeiffer and Michael
Wood for their comments on parts of the text, and to Alick
Newman and Rick Bryant for drawing the figures.
Introduction
I
It is not possible to dig a hole in a different place
by digging the same hole deeper.
Edward de Bono, The Use of Lateral Thinking
To judge from the prominence given to 'absolute dates' by earth
scientists, archaeologists and workers in allied fields, age determina
tion has come to play an essential part in the chronieling of the
history of the earth and its inhabitants. The ßourishing state of
research into existing and novel dating techniques guarantees
further progress in this direction; and progress it undoubtedly
represents to anyone curious of the past. Yet many of the principles
on which geology and prehistory rest were formulated at a time
when techniques for measuring the age of rocks and fossils were
almost wholly lacking. Do they need reassessment now that quanti
tative dating is practicable beyond the historical period ?
Geochronology has been defined as the science of dating events
in earth history. In his elassic Dating the Past, F. E. Zeuner stressed
the elose relationship between geochronology and stratigraphy, and
pointed out that all the methods he would consider relied upon
strata of some kind or other.1 The methods ineluded radiocarbon
and potassium-argon dating as weIl as those that involve the
counting of tree-rings, varves and other 'stratified' items.2 More
recently, R. F. Flint has defined the role of geochronology as the
'calibration of a time-stratigraphie sequence', elaiming that stra
tigraphy and chronology taken together provide the framework upon
which earth history is constructed.8 The alliance is not peculiar to
the Quaternary period (figure l)-the main eoncern of both these
authors-it being generally accepted that any 'absolute geologie
time scale must be built up by interpolating between suitable events