Time Machines: Scientific Explorations in Deep Time

262 Pages·1998·4.58 MB·English

by  Peter D. Ward

T i me
M a c h i n es

© 1998 Springer-Verlag New York, Inc.
All rights reserved. No part of this publication may he reproduced,
stored in a retrieval system, or transmitted, in any form or hy any means,
electronic, mechanical, photocopying, recording, or otherwise, without the ptior
written permission of the puhlisher.
Published in the United States by Copernicus,
an imprint of Springer-Verlag New York, Inc.
Copernicus
Springer-Verlag New York, Inc.
175 Fifth Avenue
New York, NY 10010
Ward, Peter Douglas, 1949-
Time machines / Peter Ward,
p. cm.
Includes bibliographical references and index.
ISBN 0-387-98416-X (hardcover: alk. paper)
1. Paleontology. I. Title.
QE711.2.W37 1998
560—dc2I 98-18393
Ml'
Manufactured in the United States of America.
Printed on acid-free paper.
9 8 7 6 5 4 3 2 1
ISBN 0-387-98416-X SPIN 10659445
C o n t e n ts
Preface vii
Introduction: Sucia Island xi
PART O N E: F I N D I NG T I ME J
1 Fossils and the Birth of the Geological Time Scale 3
2 Radiometric Clocks 33
3 Magnetic Clocks 45
PART T W O: PLACE 71
4 Baja British Columbia 73
5 Ancient Environments and the Level of the Sea 105
PART T H R E E: I N H A B I T A N TS 12 5
6 The Bite of a Mosasaur 127
7 Virtual Ammonites 147
8 The Ancestry of the Nautilus 169
9 Of Inoceramids and Isotopes J 91
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T I ME M A C H I N ES
PART F O U R: T HE T I ME M A C H I NE 2 0 5
10 Cretaceous Park 207
Afterword 223
References 225
Index 231
vi
P r e f a ce
In modern times, science has brought the past—and so many of its
creatures—back to life via intellectual inquiry, application of the scientific
method, and some extraordinary technology that has recently been devel
oped. The wonder of the process is that such a rich and vivid understanding
of the deep past has been generated from such scanty evidence: broken
bones, lithified shells, fossil leaves, and even simple layered rocks. The sci
entists who have contributed to this work have woven rich tapestries of an
cient times, and their weaving, which is an adventure in itself, is the subject
of this book. It is as if true time machines existed, enabling us to retreat
through time's mists into the past, to examine the then-living as though liv
ing still, to visit ancient worlds and reconstruct the lives their denizens led.
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T I ME M A C H I N ES
The past tantalizes us; it is part of our nature to seek clues about an
cient times and our origins. Yet the past is far more than just some moment
in time. In our own lives, for instance, it is also place, people (and other liv
ing things), and history. Take the first day of school: the desks and posters,
the windows and chalkboards, the people who left us there, the people we
met. So, too, for paleontologists and archeologists is the deep past a conver
gence of time, place, inhabitants, and their history or biological interactions.
To bring a dinosaur to life, you must journey back to a given time, the Meso-
zoic Era, the so-called Age of Dinosaurs that ended 65 million years ago. But
once there, you are in a place filled with life, and you must be able to under
stand that ancient environment and its ancient inhabitants. To reconstruct
the past, it is necessary to study all of these dimensions.
In paleontology we study the past in many ways. We use theory, com
puters, intricate laboratory equipment, and even thought experiments. Most
commonly, however, to bring the past back to life, we use rocks. The rocks
we look at are usually layered or sedimentary (as opposed, say, to lava). This
is the type of rock that contains fossils, and it is fossils that provide the key to
the hoary vaults of time.
Sedimentary rocks thus contain the best information we have for
studying the past—if only we can access that information. Any outcropping
of fossil-bearing rock holds clues to its age, and thus to the age of the fos
silized remains it harbors. The same rocks may also hold clues to their place
of origin, which might be very different from the place where they rest now.
The surface of the earth, after all, is not static but restless, its present posi
tion just a snapshot during never-ending voyages from and to. Rocks also
can yield clues to the nature of the environments where they were formed:
Did the materials of which they were composed "turn to stone," or lithify,
on land, in a lake or sea, or in a desert? Was the environment warmer or
colder, more saline or fresher, richer or poorer in oxygen or in carbon diox
ide than our earth today? Most crucial of all, these same rocks usually con
tain our best clues to reconstructing the history of the ancient life (and
death) of living forms that were present when the rocks we are studying
were taking shape.
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P r e f a ce
No single scientific operation or approach extracts all this disparate in
formation. Many scientific tools, techniques, and philosophies must be
brought to bear. We might call these devices time machines. They vary from
a rock hammer to a mass spectroscope.
Many scientists spend their lives using these time machines to resurrect
the past. The results can be spectacular, fueling the fascination of popular
culture with dinosaurs, for example, or they can be more mundane. There
are many ambiguities, however. The past no longer exists; it is really nothing
but a memory—a memory of a loved one or an earth long past, of personal
happiness or sadness or of creatures long dead. And memories, as we all
know, are often ephemeral. Two people who attended the same event, or
lived through the same history, often have quite different memories of
what transpired. Interpreting the fossil record can be like that. Different
witnesses—or different time machines—often yield quite different accounts
of what occurred. Thus there are usually multiple versions to choose from re
constructing the past. Deciding which represents "the truth" may be diffi
cult. Yet ambiguity is a necessary—and not entirely unwelcome—aspect of
studying the deep past. It happens; people argue; the arguments are generally
resolved, and scientific progress is usually (though not always) the result.
Ambiguity is thus an acceptable by-product of using time machines to study
the past, and it is one of the subjects of this book. It also greatly enhances the
wonder and fun of doing the types of science concerned with the study of the
past.
I wrote this book to show how the past is reconstructed by those of us
who study geology and paleontology—how scientists in these fields use spe
cific scientific techniques and instruments to resurrect ancient worlds. Part
of that process involves decisions about which of many memories dredged
from the past we should give most credence to. No single time machine
recreates an entire picture of the past; each is like a single color or brush
stroke, by itself often meaningless. Yet when combined with others, each
contributes to a comprehensible—and often beautiful—portrait of the past.
To show this process, 1 have profiled a very specific "past" by looking at
a particular time and place and at its inhabitants. Many others would do just
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