Winter is settling over the rolling hills of North Idaho, where I live. Snow ices the limbs of the bare aspens outside my window, while perfect flakes fall from the flat gray sky. This weather is my reality today, but it is also ephemeral; the blanket of snow will probably melt in a week or two. Three days ago, we were still awaiting the season’s first snowfall.
In fact, everything in my view is ephemeral. The largest aspen? Probably 15 years old. The window I’m looking through? Installed about 35 years ago. And beneath the snow, the hill my house sits on is made of loess, silt blown in to the Palouse region from elsewhere periodically over the last 2 million years. That’s the blink of an eye in geologic time, though considerably longer than humanity has existed.
To help readers understand how incredibly recently humans appeared, John McPhee, in his 1981 book Basin and Range, suggests spreading your arms out wide and imagining that the distance from fingertip to fingertip represents 4.5 billion years — the age of Earth. In comparison, he writes, the 300,000 years since Homo sapiens evolved is so brief that “in a single stroke with a medium-grained nail file you could eradicate human history.”
In this special issue on deep time, we go beyond that sliver of fingernail, taking a long view of the West, exploring what it was like thousands, millions and even billions of years ago, and how that history is still visible — and consequential — today. Several of the stories in this issue are grounded in Wyoming, home to the oldest rock exposed at the planet’s surface in the Western U.S.: the 3.45 billion-year-old Sacawee gneiss. Other stories offer new insights into the history of places like the Grand Canyon, how pronghorn survived the Pleistocene and an inside view of how scientists came to understand plate tectonics.
While we do cover some current happenings, think of this issue as an invitation to take a break from the churn of day-to-day, season-to-season, election-to-election urgencies. Instead, consider the forces and phenomena that have shaped our world over a much longer time frame. We hope that widening our focus beyond the scope of human enterprises deepens your understanding of the West. After all, even as our species spurs ecological and climatic chaos, Earth will continue to transform and remake itself over and over again, just as it has for billions of years. Our aim is to celebrate that deep past — and implicitly acknowledge the deep and wide-open future of the West, too.
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