As This Sign Explains => Land Rising While The River Cuts Down, Generally Results In Very Deep Canyons.
….This Is Also True Of West Virginia’s “New River Canyon” and Colorado’s “Grand Canyon”.
……. BUT, Why Is the Canyon So Narrow and Walls So Nearly Vertical?
ANSWER: Very Narrow, Steep-Walled Steep, Near Vertical Canyon Walls Probably Are Due To => The Tough Volcanic Rock, Which Cuts Straight Down, And No Wider Than It Has To.
…This Is True Of The Volcanic Rock Recognized In The Previous Photo, The /\ Above /\ Photo, and Next Two Photos.

…. “No alternate routes here. Just whichever way the river goes. It may be just my imagination, but it seems the river’s already smaller than it was an hour ago. .. Such personal transcendence of conflicts with technology doesn’t have to involve motorcycles, of course. It can be at a level as simple as sharpening a kitchen knife or sewing a dress or mending a broken chair. The underlying problems are the same. In each case there’s a beautiful way of doing it and an ugly way of doing it, and in arriving at the high-quality, beautiful way of doing it, both an ability to see what "looks good" and an ability to understand the underlying methods to arrive at that "good" are needed. Both classic and romantic understandings of Quality must be combined.” (Cont. Next)

Metaphoric Bridge Connection:
…Corresponding Metaphorically to the canyon road’s “No alternate routes… the river is narrowing“, Narrator’s discussion of Quality “narrows” to the only choice possible => In Mechanics & Everyday Chores, we have. “No alternate routes …” meaning metaphorically that => “ Both classic and romantic understandings of Quality must be combined.”

The Salmon River Gorge, ID. Here I stopped to study this sign, which explains more about the lava flows mentioned previously. …. But now, as I am composing this paragraph, I suddenly realize => I should have taken a better photo of the dramatic walls of the gorge seen (partly) in this and prior photo.

…….Another very different, example of this deep-narrow nearly vertical wall canyon cutting, may be seen on the Arizona-Nevada border. Here, the Colorado River (same river as Grand Canyon), has eroded a likewise very narrow, but much deeper cut into => A lava flow that once flowed into & filled up the then existing Colorado River Canyon. This formed a tight “plug” of strong, very durable volcanic rock. Over the years, the river gradually eroded a deep and very narrow cut. This resulted in very close, nearly vertical walls formed of very strong (and relatively new) rock.
….And note well => All this was just perfect for minimizing the cost of Hoover (Boulder) Dam, which was built into this Very Narrow & Most Unusual, Very Deep Place.
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(Photo = 111-1145 ...... ZMM Page = 262 ...... WayPt = 286i2. Photo at 287w 1667ft)