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At Home on the Range

Richard Allmendinger

Devil in the Mountain: A Search for the Origin of the Andes. Simon Lamb. xii + 335 pp. Princeton University Press, 2004. $29.95.

Geologists are, by nature, passionate about mountain ranges. We are fascinated by their beauty and become engrossed in their personal histories. Our relationship with an individual range tends to last years or decades. In short, we become quite attached.

In the pantheon of the world's mountain belts, two are particularly revered by geologists. One is the Himalayan Tibetan system, the highest and largest range on the surface of the Earth, which resulted from a colossal collision between the continents of India and Asia. The other is the Andes of South America, the second-highest range overall and the highest in the Western Hemisphere. It was formed in a quite different and less well understood manner, as the cold, relatively dense tectonic plate beneath the eastern Pacific Ocean—the Nazca Plate—slipped beneath the South American continent.

The high Bolivian Andes may owe their existence...Click to Enlarge Image

The Andes have long been known as the home of great volcanoes, but only in the past two decades have geologists realized that most of the elevation of these mountains is due not to a piling up of lava but to deformation and crustal thickening. A flurry of efforts in the 1980s attempted to show that the Andes must have been formed as the result of a collision between South America and some phantom continental fragment or oceanic plateau. These endeavors failed utterly, and the exact causes of mountain building in the Andes have remained enigmatic.

It is this enigma that drew Simon Lamb to the Andes in the late 1980s, and Devil in the Mountain is a very personal account of his quest to understand this great mountain range. Lamb's book is in equal measures a collection of personal anecdotes about his fieldwork, mostly in the Bolivian Andes, and an attempt to describe to the layperson his conclusions about how the mountains formed.

Lamb largely succeeds in describing both the scientific work and the personal motivation of a field geologist in terms that a nonscientist can understand. His prose is lively and for the most part free of jargon. His tales of adventures during individual field campaigns engage readers in a way that a straight science text could not. Most important, he describes particularly well the process by which a field geologist interprets the Earth. Novices have little idea why a geologist chooses to measure one thing but not another. Lamb sheds light on these decisions by leading the reader clearly through the iterative process of making observations and posing hypotheses to guide future investigations.

In an effort to make the book accessible, Lamb uses a plethora of metaphors and draws analogies to common objects. The Andes are variously compared to, among other things, the knee of a crouching athlete, a "fudge cake" and a saucepan of hot syrup. These efforts are largely successful, but sometimes they backfire, as when he mixes metaphors or draws analogies to objects that will be familiar only to British readers.

In the anecdotal parts of the book, unsubstantiated rumors sometimes slip through; for example, Lamb uncritically repeats the allegation that the American ambassador was behind a decision of the Bolivian government to reduce inflation by cutting all government expenditure, including funding for the Geological Survey. Also, Lamb relates some events incorrectly. For example, he credits a meeting at Cornell with having been the impetus for a German-funded group to lay out a line of seismometers across the Central Andes, but in fact, the German efforts were planned and funded long before the Cornell meeting took place.

Any geologist who has worked in the Andes, as I have, will find it difficult to be entirely objective about the book. Lamb uses the personal pronoun "I" with abandon—often at least 10 times in a single paragraph—even when relating ideas, observations and concepts shared by dozens of Andean geologists. He tries to head off criticism for this style by acknowledging in the preface that many geologists have contributed to our understanding of the Andes. Nonetheless, readers would do well to remember that Lamb is describing a journey of personal discovery rather than completely original scientific findings.

Eight pages of recommendations for "Further Reading" are furnished at the back of the book. This material gives readers access to a subset of the most important publications on the subject, including not a few of Lamb's own. He and his colleagues have published many original, influential and occasionally controversial journal articles, which have been paraphrased and presented in the latter part of the book as the explanation for Central Andean geology. To briefly summarize, Lamb suggests that climate change in the Late Cenozoic era was ultimately responsible for the unusual width and height of the central Andes. He proposes that the onset of hyperaridity along the west coast of South America reduced the supply of the water-saturated sediments that lubricated the interface between the tectonic plates. Thus higher stress was transmitted across the interface, producing a greater amount of deformation in western South America.

Lamb ends the book with an anecdote making the point that it is important to distinguish between pseudoscience and real science. However, he fails to acknowledge the uncertainty that continues to surround deeper and more serious questions about the origin of the Central Andes. Because uncertainty, which lies at the heart of many conundrums facing society, is a difficult concept for nonscientists to grasp, the book might have served nontechnical readers better by emphasizing it. Also, because Lamb's group from Oxford did not involve South American geoscientists in their research after the occasion of Lamb's initial trip, the book may help to perpetuate an unfortunate stereotype; I hope readers will not be left with the impression that there are no geologists of note in that vast continent.

Most of these criticisms will matter little to laypeople, and for them, this book does a fine job of explaining how and why field geologists go about their business. Having had many similar experiences, I was impressed with the honesty with which Lamb relates his personal reactions, concerns and miscues. Although most geologists would not admit to being repeatedly "drenched in sweat" from anxiety, the fact remains that our fieldwork is carried out in remote areas under conditions of considerable risk, and not a few of us have felt the trepidation he describes so graphically. Likewise, many of us will smile in recognition at Lamb's moments of intellectual and physical triumph, and at the glimpses of the sublime so common in remote areas. In that sense, Lamb has captured the essence of what it is to be a field geologist.—Richard W. Allmendinger, Earth and Atmospheric Sciences, Cornell University

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