1982

Basin and Range

John McPhee (b. 1931)

Anyone who’s ever flown over, driven through, or seen satellite photos of the American desert southwest can’t help but notice the undulating, almost rhythmic nature of the landscape. Across large swaths of desert lowlands in southern New Mexico, Arizona, and California as well as north into Nevada and south into Mexico, the terrain alternates in a series of long, narrow, parallel ridges separated by long, narrow, parallel valleys (the most famous of which is Death Valley). Because of those valleys and hills, geologists call this region of the world the Basin and Range Province.

Despite agreeing on a name, geologists can’t agree on the cause of the Basin and Range topography, partly because the region has had a very complex geologic history. The leading hypothesis is that subduction of the former Farallon plate under North America starting around 155 million years ago ushered in a long period of uplift and the creation of compressional mountain ranges like the Sierra Nevada and the Rockies. The remains of that plate are now fully underneath the continent, sinking into the mantle, and now causing the crust to stretch out instead of compress. As extensional forces pull on the crust, parallel faults are formed perpendicular to the direction of stretching. Blocks of crust that drop down between adjacent faults (called graben) form long valleys or basins; the ridges between the down-dropped blocks (called horst) form long hills or ranges.

The sparse vegetation of the desert southwest accentuates the dramatic geologic story that has unfolded in the Basin and Range. Among the most lauded of those storytellers is American writer and Princeton professor John McPhee. His 1982 book Basin and Range was the first of his four-volume Pulitzer-prize winning Annals of the Former World series, in which he recounts, in layman’s language but with a geologist’s eye for the natural world, the geologic history of North America and the many characters who have helped to reveal, and revel in, that history. McPhee’s writing has helped to communicate to the general public both consensus positions as well as ongoing debates within the earth sciences community. Science, as a human endeavor, needs not only great observationalists and theorists, but also great storytellers.

SEE ALSO Continental Crust (c. 4 Billion BCE), Plate Tectonics (c. 4–3 Billion BCE?), Greenstone Belts (c. 3.5 Billion BCE), The Appalachians (c. 480 Million BCE), The Sierra Nevada (c. 155 Million BCE), The Rockies (c. 80 Million BCE), Cascade Volcanoes (c. 30–10 Million BCE), The Grand Canyon (c. 6–5 Million BCE), Death Valley (c. 2 Million BCE)

Main image: A view of Basin and Range National Monument, Nevada. Inset: John McPhee, author of numerous popular science books in earth sciences.