Who among us is not interested in the history of our own blue-white planet and the origin of life, even if it is only through creation myths?
Author, Gabrielle Walker earned her Ph.D. in chemistry at Cambridge University and spent seven years as a features editor at "New Scientist." The latter experience definitely had a hand in molding her breezy, yet clear and conscientious style. She follows her intrepid geologists to the ends of the Earth like an eager cub reporter in some 1930s B-movie, peppering them with questions, almost getting trampled by an African elephant in the Namibian bush, beset by freezing fog in the Kalahari Desert, clambering down the windswept, godforsaken rocks of Mistaken Point in Newfoundland.
This book is a combination travel guide to some of the least habitable places on earth, biographical sketches of the scientists who developed and tested the 'Snowball Earth' theory, and an introduction to the painstaking science behind the newest, most audacious 'deep time' history of our planet.
Before we get to 'Snowball Earth,' let me give you a flavor of Walker's running travelogue. Here she is speaking of Mistaken Point: "Nobody could love these barren lands, not even their mother. They are dreary and damp, their plants the color of overcooked spinach and rusty nails; when the wind is not buffeting them or rain beating them down, they are shrouded in fog. The pale, thin caribou wander over them like lost souls."
Now, on to the theory as expounded by this book. Several times in the history of Earth, most recently 700 million years ago, our planet froze completely over, possibly because all of the continents had migrated close to the Equator. This deep-freeze may have ended the multi-billion-year reign of single-cell slime and given a kick-start to the Cambrian explosion of complex life. Snowball Earth was finally melted by a build-up of carbon dioxide in the atmosphere, courtesy of volcanic eruptions which turned our planet into a hellish, hurricane-ripped green-house. Eventually the excess carbon dioxide was absorbed back into the oceans and the planetary crust. Multi-cellular life reveled in the first decent climate it had ever experienced, not realizing that meteor strikes and volcanic eruptions would occasionally wipe out up to 90% of its evolved species.
Could we get a repeat of Snowball Earth? Sure. As a matter of fact, the continents seem to be sliding toward the Equator again, which will allow ice to build up at the Poles and advance toward Earth's bulging midline. Will this happen during our lifetime? Nah. As Gabrielle Walker so vividly expresses it, the continental plates move at roughly the same speed our fingernails grow.
The geologists, paleontologists, and their science form the core of this marvelously written book. Walker does a meticulous job of relating both the scientific and the human side of the 'Snowball Earth' controversy. Her incisive portraits of the scientific movers and shakers, most especially the fiercely competitive Paul Hoffman, will stick in your mind long after you forget about drop stones, tidal rhythmites, and magnetic reversals in the Flinders ice rocks.
Geologists since the eighteenth century have advocated "uniformitarianism," the concept that what is going on to the Earth now is essentially the same as what has gone on before. It is a good rule of thumb, but like most rules of thumb, it requires intelligent neglect or violation, and working geologists do so to form an accurate picture of Earth history. There has sometimes been resistance to violation of the rule; the wipeout of the dinosaurs by an asteroid hit 65 million years ago is now generally accepted, but was not when it was proposed. But even without extraordinary outside forces, our globe used to be a very different place. Between 750 and 590 million years ago, there were sudden lurches in climate that froze even lands at the equator. Or so goes the Snowball Earth Theory. _Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as We Know It_ (Crown Publishers) by Gabrielle Walker describes the theory and its importance, but the current importance may not be merely its scientific significance. What makes the theory particularly interesting right now is that it is being championed by a colorful Harvard geologist who is attempting to make it accepted geological thought. Walker's surprisingly exciting book is thus not just a summary of ancient geology, but also an entertaining examination of personalities involved.
The snowball Earth theory is not entirely new, but the book is largely the story of Paul Hoffman, a brilliant, driven geologist who was eager to make some sort of difference in his field. Argumentative, energetic, and brilliant, he has a strong reputation as a geologist and as a difficult character. Disputes by him are not objective quibbles published in obscure journals, but stand-up, screaming fights. Partially because Hoffman has taken up a sort of gladiatorial grandstanding for the theory (he has made his own contributions and confirmations), there are equally adamant anti-snowballers. The combative nature of science is on display here; Walker writes, "Science works at its best when somebody puts forward a theory and everyone else tries to pull it down." She is good at describing the pains of field work (something at which Hoffman is adept), but academic battles are the emphasis in her book. Of course Hoffman hopes his ideas share the same fate as those of Alfred Wegener, whose ideas about Plate Tectonics were originally ridiculed; so far, they have survived the challenges about which Walker reports.
Particularly valuable in the theory is the light it might throw on the bloom of life into complex multicellular creatures. Of course a deep freeze would have been disastrous for all the simple slimes that were found all over the Earth when the freeze came. There might have escaped, however, pockets of cells that, according to the theory, were the precursors for the famous Cambrian explosion in the trilobite times. Perhaps the snowball produced the complexity, although this is far from clear. It is one of the many details that is going to have to be argued over. Walker winds up with a description of the Earth's future; if we are still around in a few hundred million years, we might well have to deal with a return of the snowball. It is too hard to think about time lengths of such spans, but geologists routinely do so, although the spans are back in the past. Walker's book is a good introduction to serious thought about such times, and to the very human way such science is done.
on April 7, 2003
This book is about the theory that, over 600 million years ago, the earth underwent periods when it was completely covered with ice, hence, Snowball Earth. Although many scientists have contributed to this theory over the past few decades, the book focuses mainly on the efforts of Dr. Paul Hoffman, the main scientist responsible for developing and promoting the theory, thus raising its status to level that it has today. This is a very well-written book. It vividly describes the way in which science works, as well as the fact that scientists are all too human. It also contains well-written discussions on the science involved. Such a book should contain diagrams, figures, charts, photos, maps, etc., to better illustrate the locations, ideas and facts presented in the text. Unfortunately, the book contains none of the above - no picture whatsoever; if it did, I would have easily given it 5 stars. Despite this shortcoming, the book is definitely worth the read.
on June 8, 2003
This is an excellent read, for scientists and non-scientists alike. How often do we get snapshots of scientific controversies as they evolve? I can't think of any. And it is an accessible and fascinating controversy for the literate public. Ms. Walker has bent over backwards to keep the geojargon out, and I applaud this. She has done a great job of presenting the scientific problem and the psychological drama implicit in resolving this within the scientific community. Her vignettes of the personalities are great and she pulls no punches. All are presented as humans, with incisive assessments of strengths and weaknesses. She does a great job presenting how they interact, and this for me was the best part of the book. The footnotes are unusually useful and entertaining; would that all footnotes were as readable. I like the way that she uses footnotes to steer the interested reader to other papers and books. The decision not to have photos or maps is strange, this was a mistake that I hope she does not repeat in her future efforts. We may be witnessing the beginnings of a great career in writing science here.
Gabrielle Walker's "Snowball Earth" reads like a gripping detective tale and spellbinding memoir. Her relatively terse epic primarily tells the tale of arrogant, maverick Canadian geologist Paul Hoffman, and how his study of Precambrian geological formations in Namibia, Africa lead inexorably to a new, controversial theory in the geological sciences; "Snowball Earth". Possessed by a zeal equalled only by a religious fanatic, Hoffman, a professor of geology at Harvard University, gradually builds up an impressive theory explaining how the Earth was encased in ice, not once, but probably at least four times, over the course of two hundred million years (He believes it began around eight hundred million years ago.). Furthermore Hoffman has suggested that this was the event which triggered the evolution of metazoan life and the subsequent Cambrian explosion of metazoan phyla. Walker also introduces us to Caltech geologist Joe Kirschvink whose work in magnetostratigraphy supplied important clues that aided Hoffman in shaping his theory. But to her credit, she also spends considerable time discussing important critics such as Columbia University's Nicholas Christie-Blick and University of California, Riverside's Martin Kennedy and noting their substantial objections without sounding dismissive. Told in engaging lyrical prose, Walker's book will interest anyone fascinated with research done by field as well as laboratory geologists. Her book is a splendid little ode to exciting state-of-the-art geology and some of its most fascinating scholars, most notably Hoffman, himself. Without question, this is among the finest popular books on geology that I've come across.
Gabrielle Walker's first book portrays the struggle of a renegade scientist to establish a theory of evolution's progress. Charles Lyell's established "uniformitarianism" in geology, followed by Charles Darwin's application of it in his theory of evolution by natural selection. The concept of gradual change in life as reflected in the fossil evidence is being challenged by some scientist. Paul Hoffman's research in Namibia indicated that Earth was subjected to an intense Ice Age prior to the Cambrian, severely interrupting life's progress. Walker introduces us to Hoffman and other major contestants in this game of reading the rocks. She presents him and the arguments with dynamic style, giving the book a certain panache.
Even under Walker's admiring scrutiny, Hoffman doesn't appear as an endearing figure. Yet, the very characteristics some find irritating are the same drives that kept the theory of Snowball Earth alive. Walker shows how combative science can be, with contenders sniping and quarreling like feuding families. They all have fossils, climate mechanisms and glacial processes on show. Walker attempts to give them all a hearing, but the opponents make but cameo appearances. She gathered her evidence by extensive journeys - her travel budget must have been prodigious. Walker reveals their peccadilloes and their strengths. When you are done, you feel a sense of identity, even intimacy with them.
Whether you are convinced of the thesis remains problematic. Walker's own sketchy knowledge forces a pause, wondering about the validity of her presentation. Her admission of being a "Snowball Earth groupie" erodes credibility. She offers many assertions as givens, such as the asteroid dinosaur extinction thesis. Theory popularity is good journalism, but sketchy science. Her journalist role leads her to overuse of buzzwords - "Slimeworld", the habit of bacteria to form mats - achieves fatiguing redundancy.
The predominant question, which Walker addresses only superficially, examines what process life underwent under these conditions. There was life before the Cambrian - clearly multi-cellular. How complex was it, and how resistant to the environmental crisis evoked by the Snowball Earth hypothesis? Ediacaran life was shallow sea bottom or surface dwelling. An ice blanket a kilometre or more thick would have been devastating to this population. Walker and her "group" are unable to form a coherent thesis of how life achieved complexity after the Snowball's meltdown, only that it must have happened - otherwise "we wouldn't be here". A valid statement, but one needing further support for how it might have occurred.
Walker's personalised account makes engaging reading, presenting a new idea needing more attention. While various modifications of the Snowball Earth notion have been offered, final judgment remains deferred. This is a good, but limited, overview of the debate and the participants. At some point, someone qualified will enlighten us further. [stephen a. haines - Ottawa, Canada]
on May 9, 2003
It is fascinating to watch the unfolding of new scientific theories, particularly after having lived through some of them. For example, when I first began studying geology, continental drift was just beginning to be accepted. This book advances some interesting ideas in Earth history that seem to have good evidence for them. It's also well written and entertaining (although, I agree with the other reviewer who called it too "dumbed down").
The book really, really needs illustrations (there are NONE), and it's astonishing that it does not have them, given the opportunities. There are the stunning landscapes of Namibia and Svalbard that could appear. There really should be photos of the Hamelin Pool, of Stromatolite fossils, of the minerals and rock formations, and of the geologist protagonists. I'd recommend fifty color photos, and I will buy another copy if a new edition is produced that way.
Minor gripe: There's only one place in the world one can have an "intercontinental train" -- and it's not Canada. Proofreader, hello?
All in all, a very worthwhile read.
For those who may wish to study the matter further, there is a "snowballearth.org" with a lot of bibliography, photos, etc. Increasing interest in Precambrian glaciation has resulted in many new scientific papers in the last few years.
on January 7, 2004
I honestly couldn't put this book down.
I'm a microbial ecologist, and I picked up the book looking for insights into the history of early life on earth. I had read the significant Science and Nature papers on the subject of Snowball earth, but this book was something else entirely. I nearly forgot about my interest in the subject matter and was enthralled by the characters that Walker brought to life.
Snowball Earth is a nice 'story', and I am eager to see how this theory plays out in the coming years. I like it as a working hypothesis for the moment, and I am intrigued by the proposed link between Snowball events and metazoan evolution. The timing seems right, but I don't think a compelling mechanism has really been put forth yet.
Walker does a thourough job on this topic, and I hope she writes more books!
on June 22, 2005
I truly enjoyed this book. It revealed the scientific theory more in the form of a story than just a book of factual information pertinent to the theory.
One need not have any knowledge of or even much interest in geology to enjoy this book. The basic outline of Snowball Earth is that there is extensive geological evidence that there was a global freeze-over about 700 million years ago that ended the precambrian era of unicellular "slime", and possibly caused or affected the following cambrian explosion.
This book is very much a story of Paul Hoffman and his friends and colleagues, and I would not recommend it for someone looking for an in-depth explanation of the snowball theory.
on June 30, 2003
I first heard about the Snowball Earth theory when I saw a documentary about it on the Discovery Channel. I'm usually more of an astronomy fan, but that documentary fascinated me. I picked up this book following that on a chance sighting, and it did NOT disappoint. The book covers the theory, in layman's terms, and the personalities behind the theory, both for and against.
I think that the few poor reviews here are due to a misinterpretation of the book's purpose. Taken as a book meant to actually make a profit by interesting everyday readers, it was excellent. "Science snobs" who feel their points of view under-represented may take offense, but for the rest of us, thank you Miss Walker.