By Jan Zalasiewicz
Oxford University Press, 234 pp.
The Planet in a Pebble tells the story of the history of the earth as it can be inferred by a geologist thinking about a pebble. In this sense, the book is evocative of Thomas Huxley, who did the same in 1868 using a piece of chalk. Zalasiewicz, however, uses every method available in the 20th and 21st centuries, from the scale and style of field work to the microsopic detail provided by state-of-the art laboratory analyses now available to tell the story. In popular jargon, this is forensic geology. The intended audience appears to be the scientifically literate and interested. Given the state of science literacy in the U.S., this will, unfortunately, be a small audience here.
Zalasiewicz has studied the Welsh slate, a rock that had the “alas, reputation of being wet, grey, and monotonous,” for much of his career with the British Geological Survey, and is superbly qualified to tell this tale. He is the author of “The Earth After Us”, speculations on the state of the planet after humans are no longer a part of it. He is also a gifted writer who clearly loves the language. Two paragraphs from the prologue capture both the essence and the style of the book:
“It is just an ordinary pebble. One of millions that wash backwards and forwards on the world’s shorelines, or pile up on riverbanks or perhaps line your garden path. Yet that pebble, like its myriad kin, is a capsule of stories. There are countless stories packed tightly within that pebble, more tightly than sardines in the most ergonomic of tins.
The size of this story-capsule is deceptive. These stories are gigantic, and reach realms well beyond human experience, even beyond human imagination. They extend back to the Earth’s formation—and then yet farther back, to the births and deaths of ancient stars. Something of the Earth’s future, too, may be glimpsed beneath its smooth contours. Battle, murder, and sudden death are there, and ages of serenity too, and molecular sleights of hand that would make a magician gasp; there are extremes of cold in those stories. And also temperatures that far surpass the heart of our sun.”
Zalasiewicz says that humans love stories, are born storytellers, and he successfully tells a story here. Beginning with a chapter entitled “Stardust,” he introduces the concepts of atomic matter from which his pebble is built, and then moves on to briefly introduce the current structure of the earth’s interior before getting to the core of the book: minerals and sedimentary rocks. How were the Welsh slate pebbles actually formed and how do these pebbles relate to the “deep time” of geology that goes much further back in time than the age of the slate itself (410-570 million years)? He ends with speculations on the future of the pebble, and a nice suggested “further reading” list.
Along the way, he does a nice job of conveying the feeling about what the profession of geology is like, and the nature of the techniques that we use.
My criticisms of the book are truly minor. I was puzzled (as were several colleagues to whom I showed the book) why the front cover had brightly colored pink, grey and white rocks, perhaps even granites or sandstones(?) when the whole theme was the “wet, grey, and monotonous” shale. The back cover and chapter photos certainly show that there are plenty of beautiful grey rocks that could have been featured! If meant to challenge the reader to think about the story in every pebble, it’s too subtle, but perhaps it helps get people to pick up the book because it's more attractive than a collage of grey rocks? I also think that putting the List of Plates right in the front of the book immediately after the Table of Contents was a mistake. These captions are full of technical terms (graptolites, monazite, “tectonically thickened barrel-like mica”) that will discourage any casual reader who is not a geologist from turning more pages. A figure showing the terms used for the geologic time periods would have been helpful.
At this time, when there is such a need for science communication, Zalasiewicz’s contributions and talent are most welcome. I recommend this book not only for the well-told story of earth history, but also for the beautiful writing.