134 
THE GEAND CASTON DISTEICT. 
leave it and ascend its right bank to the upper platform. The way here is 
as pleasant as before, for it is beneath the pines standing at intervals, vary- 
ing from 50 to 100 feet, and upon a soil that is smooth, firm, and free from 
undergrowth. All is open, and we may look far into the depths of the forest 
on either hand. We now perceive that the surface of the plateau undulates 
with rolling hills and gently depressed vales. These valleys are the rami- 
fications of the drainage channels. They are innumerable and cover the 
entire surface of the plateau. The main channels all deepen as they 
approach the edges of the plateau and often attain considerable depth, be- 
coming at the same time precipitous. The deepest are those which emerge 
near the elbow of Stewart’s Canon and north of that point. These attain 
depths exceeding a thousand feet. The ravines which descend towards the 
eastern flank of the plateau terminate in a different manner, which we shall 
see hereafter. In the interior parts of the plateau these drainage valleys 
are all shallow, rarely exceeding 300 or 400 feet in depth, and seldom 
abrupt. 
After two or three miles upon the summit, the trail descends into 
another valley, whose course we follow upward for about seven miles. At 
the distance of about twenty miles from Stewart’s Canon, we find that we 
have gained about 1,400 feet of altitude, and that the vegetation has changed 
its aspect somewhat. The pines, though still abundant, are now in the 
minority, and the spruces and aspens greatly predominate. The spruces 
form dense thickets on either hand, which nothing but the direst necessity 
would ever induce us to enter. Of this genus there are several species, 
varying much in habit. The great firs (Abies grandis, A. Engelniamii) are 
exceedingly beautiful on account of their sumptuous foliage. But the most 
common species is a smaller one (A. subalpim), with a tall and straight 
trunk, its branches spreading only five or six feet. These trees cluster so 
thickly together that a passage through them is extremely difficult and 
sometimes impossible. But we are not constrained to attempt it, for they 
seldom grow in the valley bottoms. Again we leave the ravine, and wind- 
ing about among the hills, passing from glade to glade, we at length find 
ourselves upon the summit of a long slope, which descends rapidly into a 
great park, the largest on the Kaibab. It has received the name of 
