We are often told to write about what we know. With all due respect, this is terrible advice and is easily misconstrued as “write about what you already know.” There is no doubt that your own knowledge is valuable, your own experiences compelling, and your own backstory compelling. We all agree, but the accumulation of one life rarely adequately prepares us for the task of writing. If you are, say, Volodymyr Zelensky or Frederick Douglass or Sally Ride, the category of “what you know” may actually be unusual and important enough to deserve print. For the rest of us, a better, if less succinct, maxim would be “go out and learn something interesting before you write.”
Marcia Björnerud is a believer in this adage, as the first of her five published books is a textbook. Björnerud is a professor of geological science at Lawrence University in Wisconsin, and the Earth has been her object of study and fascination for over 40 years. Her first book for the general public was “Reading the Rocks,” a beautifully clear account of the Earth's history from the geological record. Her second, “Timefulness,” explores the Earth's eternal flow of time and invites us to incorporate it into our own, much more fleeting sense of time, as a precaution against the dangers of short-term thinking. Her third, “Geopedia,” is an alphabetical overview of her research fields, from Acasta gneiss (one of Earth's oldest rocks) to zircon (Earth's oldest mineral, 4.4 billion years old, just a little younger in cosmological terms than Earth itself).
Earth is Earth after all, and Björned's latest book, “Turning to Stone” (Flatiron Press), is in some ways familiar territory. But it's also a surprising departure, in that it's not just about Earth's life, but also about the author's life. Within its pages, what Björned learns helps to clarify what she already knew. Each of the book's 10 chapters is structured around a different rock that provides background for a particular era of her life, from childhood to the present. The result is one of the rare memoirs in recent memory that combines personal history with a detailed description of the building blocks of Earth. What the two parts of the story have in common is an interest in the evolution of being, the mundane and cosmic forces that shape us.
Bjorned grew up in rural Wisconsin, 40 miles north of the Little House in the Big Woods where the earlier memoirist had lived for a time. By the early 1960s, when Bjorned was born, the vast forests that Laura Ingalls had known had been cut down, leaving only pastures, scrubland, scattered second-growth forests, and devastating erosion. As soon as the trees were gone, the soil washed away, for the soil was sandy; it was clear evidence of the bedrock that lay beneath: sandstone.
That we come across the sandstone before meeting Björned’s parents says something about her. She’s not interested in autobiographical comprehensiveness, but rather reconstructs her life in the same way that geologists reconstruct the past, using bits and pieces to tell a larger story. When we meet her in the first chapter, she’s seven years old, on her way to school, and the glimpses of her classmates boarding the bus are almost novel-like. Three Mennonite sisters, with neat braids and gingham dresses, exude an aura of community that Björned envies; a rosy-cheeked farm kid who inspires the same jealousy when the smell of bacon wafts through the air (“We’re not a family that eats hot breakfasts”); and a little boy with a limp, chronic absence a harbinger of the diseases that will kill you in your twenties. The overall effect is the familiar inverse correlation between rural intimacy — the number of people you know — and how much you know about someone's siblings, parents, great-grandparents, their struggles, secrets, tragedies, and so on.
When it comes to these personal matters, Björnerud is forthcoming but not dwelling on them. Her father appears primarily as the man who built the family home and scavenged second-hand goods to fill it. All we know about her mother is that she was abandoned by her own mother as a child, which left her prone to melancholy (“above the Scandinavian norm”) and highly sensitive to the plight of orphans. As a result, she and her husband adopted a 19-month-old Ojibwe girl in 1968; Björnerud was just about six at the time. The two girls were close in childhood, but the socially awkward Björnerud soon discovered that her strategy for avoiding ridicule from her peers – keeping a low profile – did not work for her younger sister, who was constantly under scrutiny and the target of both casual and malicious racism.
Though Björned's birthplace largely disappears from the pages after the first chapter, we can feel its influence, especially in the honest and knowledgeable way in which Indigenous history permeates her story, as it does the rest of human history. Despite her abiding passion for the distant past, she remains attentive to the 0.007 percent of Earth's lifespan that has been inhabited by humans. She likes to call us “Earthlings,” reminding us that our most pressing identity is as creatures who evolved on and depend on this planet, and arguing that our lives are profoundly and continually shaped by the ground beneath our feet.
“Why do they always do that on concrete? When your feet are the best part?”
Cartoon by Peter Steiner
Consider sandstone. It began as quartz crystals buried deep within the mountains of what are now the northern Midwest and southern Canada, about 2 billion years ago. Over time, the mountains collapsed and rain dissolved most of the minerals within them, but the quartz remained. The quartz was then washed down Precambrian rivers and eventually to the coast, where the waves wore the quartz particles down to a smooth, spherical shape. That coast was in the tropics, partly because the climate was very warm at the time, but also because Wisconsin was close to the equator at the time. As the oceans receded and other rocks and minerals were deposited on top of the earlier sandstone, the quartz particles hardened into sandstone, which was gradually eroded by wind, water, and glaciers to form the Wisconsin topography we know today. Below ground, the spherical particles formed excellent aquifers, leaving plenty of space between the particles to store water, in Bjornerud's words, “like marbles in a jar.”
In Björnerud's hometown, the sandstone can be seen in the mansions that once belonged to logging magnates and in the grand old public library. But it also made its presence known in more subtle ways, in determining “where to build houses, where to dig wells, what crops to grow, who would get rich, who would go into debt.” The sandstone made the ground too sandy and unsuitable for farming, making it hilly and impossible to cultivate efficiently enough to keep pace as large-scale agriculture began to dominate the otherwise flat lands of the Midwest. To survive, farmers had to use more and more fertilizer, and each rain carried some of the nitrogen from that fertilizer into the porous sandstone. Eventually, tests of local well water began to show high levels of nitrates, which limit hemoglobin's ability to carry oxygen. The danger wasn't theoretical. “I remember neighbors whispering frightened whispers,” Björnerud writes. “One of our former babysitters, who had married a hard-working young farmer the year before, gave birth to a 'blue baby' who died a few hours later from exposure to nitrate-contaminated groundwater in the womb.” The field of hydrogeology (which involves the study of how water flows into and through aquifers) was just starting out, and Björnhardt herself was still a child. But she had just had her first flash of an idea that would become the basis of her future career: that geology, like geography, could be fateful.
Of all the scientific fields, geology alone suffers from a reputation for being irredeemably boring, with all the boring fieldwork of paleontology and no Velociraptors. Compared to the brighter, but more insidious, science-related concerns that preoccupy us today, from climate change to AI, geology seems not just innocuous, but largely irrelevant. Ask people to name a STEM field and the chances of them saying “geology” are virtually zero.
Given this low cultural status, few students in college aspired to become geologists, and Björnörd was not one of them. Leaning toward the humanities, she enrolled at the University of Minnesota with the vague idea of learning languages and becoming a translator. Like countless students before her and since, she took an introductory geology course just to fulfill her graduation requirements. She soon became fascinated with rocks, both for their own value and as “a portal to the Earth's hermetic interior life.” She was struck by the way rocks reveal “the strangeness of the Earth: its tectonic habits of self-renewal, its ceaseless recycling of primordial materials, its literary urge to record its own history.” She changed her plans, found her calling, and became a translator of a language that, in some ways, is closer to Ur than Ur.
Even with all those petrology classes for jocks, the language is horribly hard to master. The field of geology encompasses almost 5 billion years of history, and to properly understand it, you need to understand everything from the distribution of minerals at the beginning of the solar system to the physics of convection in the Earth's mantle. To make matters worse, even if you limit your focus to the present, most of what you study is blocked from view. The Earth's crust is less than 2% of the Earth's total volume, and much of it is invisible to the naked eye, hidden by vegetation, submerged in oceans, or buried under layers of rock that aren't the rocks you're looking for. As for everything that's under the crust, it's totally inaccessible outside of Jules Verne's imagination. The deepest hole humans have ever dug is the Kola Peninsula Superdeep Borehole, planned by the Soviet Union during the Cold War, which is 7.5 miles deep, about 0.2 percent of the distance to the center of the Earth. Humanity has done better in the past at sending itself and its equipment into space.
