A hogback is so called because of its resemblance to the dorsal ridge of stiff hair on a wild hog’s back. A long, narrow-crested ridge of exposed rock, geologically it is stratum that has been tilted until the originally horizontal beds are nearly vertical. (The beds must be tilted at least thirty-five degrees above the horizontal to be called hogbacks; otherwise they’re cuestas.) Hogbacks are common in the Black Hills of South Dakota, where sedimentary rock was uplifted by the intrusion of Black Hills Granite. Some of the most striking hogbacks occur in Colorado, in such places as Garden of the Gods and near the city of Boulder, whose storied geological backdrop, the Flatirons, is a type of hogback. The Navajo term for a hogback a few miles northeast of Mexican Hat, Utah, is Dzi-l Na‘neest‘ee‘i, “Mountain That Is Twisted.” Hogbacks are sometimes called razorbacks.

Barbara Kingsolver