Snowball Earth: The Story of the Great Global Catastrophe That Spawned Life as We Know It

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.

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 shaker

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.

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.

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.