A reference to the chapter "How the Canyon was Formed," will explain how this side gorge came into existence, and also account for the great upthrust of the granitic rock at its mouth, for the most casual observer cannot fail to note the presence of this rock much higher than it is seen elsewhere.

The North Wall. Before paying particular attention to the vast forms that crowd the interior of the Canyon, let us follow the "build" of the massive wall on the north side. This is part of the great Kaibab Plateau, the highest wall of the whole Canyon system. Its elevation is eight thousand three hundred, as against six thousand eight hundred and sixty-six feet at El Tovar, and it is thirteen miles in an air line from the south rim, where the hotel is located, to the north rim.

The reason for this difference in elevation is explained in the chapter "How the Canyon was Formed." In brief, it is that, during a process of " faulting," the north wall was thrust up above the level of the south wall.