On the east it descends four thousand feet by a Monoclinal fold, which passes into a fault towards the north.
"The Elements of Geology"
William Harmon Norton
But that the trough is a true valley of fracture is proved by the fact that on either side it is bounded by fault scarps and Monoclinal folds.
"The Elements of Geology"
William Harmon Norton
The intercanyon valleys of this portion of the Grand Canyon extend back from three to seven miles west of the river, and are eroded in the crest of the Monoclinal fold that forms the eastern margin of the Kaibab Plateau.
"The-Grand-Canyon-of-Arizona-how-to-see-it"
James, George Wharton