12 October 2022

Geopedia, by Marcia Bjornerud

Posted by Callan Bentley

My favorite popularizer of modern geology is Marcia Bjornerud. Her sensibility for what is interesting and important matches very nicely with my own – I feel she is a kindred spirit, though one infinitely more talented with language than I am. Lovers of geology found much to delight them in Reading the Rocks. She took the geological into the realm of the philosophical and political in Timefulness. This book (her third, a “pandemic project”) is a fun, trim little compendium of geological words. It relishes the exotic origins and fun flavors of geological jargon, and explores each word or phrase in a page or two, teasing out the big “take home” message in short order, and somehow managing to deliver cogent, coherent, condensed summaries of geological big ideas with a balance of economy and ebullience. Perhaps the best example of this is the short little “taglines” for each entry:

Yardang Gone with the wind
Jökulhlaup Breaking the ice
Bioturbation The worm churns

I read the whole book (it’s only 168 pages) in two days, and I’m very keen on reading it again soon. I think I’ll quote passages from it when discussing komatiites and zircons, eclogite and pseudotachylyte. To me, one of the most striking passages was the entry on pedogenesis, the making of soil. You might expect an entry on dirt to be boring as hell, but she frames it in the context of how precious a set of circumstances are required to make soil – circumstances that cannot be expected on other planets, and only induced at great expense over vast spans of time. Those who would glibly “TERRAFORM MARS” would do well to spend ten minutes reading this trim little entry, which effortlessly guts their oversimplified vision. Earth makes earth very well, and we would do well to appreciate our home and conserve it rather than make a go for Plan(et) B. Marcia recently visited with my students via Zoom, and read us two passages from Geopedia: one on the Tully Monster, and another on a favorite topic: boudinage, which she illustrated using imagery from this blog! 🙂