On the Origin of "Deep Time"

How language shapes geology

Jul 08, 2025

"At any location on earth, as the rock record goes down into time and out into earlier geographies it touches upon tens of hundreds of stories, wherein the face of the earth often changed, changed utterly, and changed again, like the face of a crackling fire."

— John McPhee, Basin and Range

When I first read John McPhee’s Basin and Range in college, it cracked something open in me. The pages gushed with gems like the passage above, language that had me falling as much in love with the art of turning science into prose as with the subject matter of the book itself. It was the first thing I ever read that made me want to become a science writer.

I began rereading Basin and Range in 2021, soon after getting my book deal. I scratched notes in margins, splattered post-its across pages, kept a long list of ideas I hoped to weave into my own manuscript.

On this second read, I paid more attention to the ways that McPhee delighted in the language of geology.

“It was a fountain of metaphor,” he writes of his early discovery of this discipline.

Pillow lavas. Volcanic bombs. Radiolarian ooze. He dishes out these low hanging fruits of geologic phrases, and the reader can’t help but delight in them alongside him.

But it’s not just geology’s terminology that makes it so fun to play with on the page. It’s also the frame of mind that geologists must adopt:

“They look at mud and see mountains, in mountains oceans, in oceans mountains to be.”

The metaphor is the science and the science is the metaphor.

Only once I dug further into my book research did I discover that one particular metaphor that McPhee included in Basin and Range was actually his own invention, not one he had plucked from a textbook:

Deep time.

This phrase, first popularized by McPhee in 1981, now appears in more than 74,000 Google Scholar search results. Geologists use it as liberally as “granite” and “schist,” but it has its origins in literature rather than research. How fitting it is for the humanities of the sciences to so openly adopt a term popularized by a purveyor of prose.

Basin and Range has now been out in the world for nearly 45 years. It is beginning to feel like a thing of the past. But in the scope of deep time, this phrase that the book introduced is only just beginning to enter the common lexicon.

“Deep time” is younger than my parents.

It’s younger than the house I live in.

It’s younger than the tree in my backyard.

We're only just beginning to have words to express the depth of narrative in Earth’s crust. The state of mind it cracks open, the language it blooms out.

One Week ‘Til Launch!

We’re one week away from the launch of Strata: Stories from Deep Time. The whole point of writing this thing was to share it with readers, and I’m so looking forward to finally being able to do that!

Media coverage has begun rolling out, including an excerpt in Rolling Stone:

And a shoutout in the LA Times as a Top 10 book to read in July:

I’m over the moon that they are recommending it as a beach read, both because they deem it that digestible, and also — what better place to read a book about ancient sediments?

Sarah Gilman’s Illustrations

I was lucky enough to work with the ridiculously talented illustrator + writer + editor Sarah Gilman on a series of illustrations for Strata. Four of those prints are now available in her Etsy shop, including this beauty: