LIVING UNDER A ROCK

A geologist reflects on her life.

- KATHRYN SCHULZ

Write about what you know, they say. All due respect, that’s lousy advice, far too easily misinterpreted as “write about what you already know.” No doubt you find your own knowledge valuable, your own experiences compelling, the plot twists of your own past gripping; so do we all, but the storehouse of a single life seldom equips us adequately for the task of writing. If you are, say, Volodymyr Zelensky or Frederick Douglass or Sally Ride, the category of “what you know” may in fact be sufficiently unusual and significant to belong in print. For the rest of us, the better, if less pithy, maxim would be: before you write, go out and learn something interesting.

Marcia Bjornerud is a follower of this maxim, which we know because, of her five published works, the first one is a textbook. Bjornerud is a professor of geosciences at Lawrence University, in Wisconsin; the interesting thing she has been learning about, for more than four decades, is our planet. Her first book for a popular audience was “Reading the Rocks,” an admirably lucid account of the Earth’s history as told via its geological record. Her second, “Timefulness,” was an exploration of the planet’s eons-long temporal cycles and an exhortation to incorporate them into our own far more fleeting sense of time as a safeguard against the hazards of short-term thinking. Her third, “Geopedia,” was an alphabetical overview of her field, from Acasta gneiss (one of the Earth’s oldest known rocks) to zircon (its oldest known mineral, at 4.4 billion years, a cosmological hair’s breadth younger than the planet itself ).