From The Hot, Dry, Barren Salmon River Canyon =>
….We Come Back Up To Cooler, Moist, Meadows, Surrounded By Green Forests.

….“ …. and afterward the road branches away from the canyon and follows a smaller stream. It seems to head upward into forest.
.... It does, and soon the road becomes shaded by tall, cool pines. ” (Cont. Next)

In The Valley of New Meadows, ID. Just as the Narrator described in the passage above, the road does indeed branch from the main river channel and follow a smaller stream ever upward.
….Here we follow the Little Salmon River in an ever narrower V shaped canyon, and eventually arrive into trees, which suddenly widens to this beautiful wide flat valley, shown in /\ Above /\ Photo.
To Read About How It Is That => “A Narrow V Valley Can Suddenly Widen Into A Beautiful Wide Flat Valley.” Right Click and Open In A New Tab.
NOTE: AFTER this Blue Link Comes Up => You will have to take into account, that moving “upstream” reverses a “downstream” explanation.
(Better photos of all this scenery, are needed.)
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(Photo = 111-1154c ...... ZMM Page = 267 ...... WayPt = 290i. Photo at WayPt = 291w 3879ft)