190 EXPLORATION OF THE CANONS OF THE COLOEADO. 
(The plateaus and tables, the faults, and folds, and the escarpments, 
due to displacement and erosion, are exhibited in bird's-eye view, Figure 
72, and also in section and bird's-eye view, Figure 73.) 
CLIFFS OF EROSION. 
I have said that the upper surface of the district adjacent to the Grand 
Canon is the summit of the rocks of Carboniferous Age. North of the 
Grand Canon, from forty to sixty miles, we find rocks of later age, standing 
in cliffs, the escarpments of which face the south. There are four lines of 
these, preserving, in their courses, a general parallelism. Going north from 
the Grand Canon, we first meet with the SMn-ar'-ump Cliffs, a step to a 
bench, low, and much broken. Capping the cliffs, we find conglomerate, 
over which are scattered many fragments of silicified wood, known to the 
Indians as the arrows of Skin-au'-av, or Skin-ar'-ump. Still proceeding 
north, we come to a second line of cliffs, with soft beds below, and harder 
beds above, known as the Vermilion Cliffs. The rocks exposed in these two 
lines of cliffs have been, by courtesy, called Trias, but without sufficient 
paleontological evidence. The third line of cliffs has a gray, homogeneous 
sandstone at the base, and a capping of limestone, containing Jurassic fossils. 
Above this line we have many hills, carved out of beds- of Cretaceous Age, 
and above and beyond these hills, a line of cliffs, the summit of which is of. 
Tertiary Age. The faces of these upper cliffs are stained with red oxide of 
iron, and they are called the Pink Cliffs. The dip of the beds is to the 
north; the strike east and west; and as these are cliffs of erosion, they fol 
low the strike in a general way, and hence have an easterly and westerly 
trend. 
The ascent from the foot of the Shin-ar'-ump Cliffs to the summit of 
the Pink Cliffs is but 4,000 feet; but as the dip is to the north, in the direc 
tion of the ascent, the thickness of the beds passed over is much greater, 
being more than ten thousand feet. 
I have said that these lines of cliffs have an easterly and westerly 
course, but they deviate greatly from this general direction in many places. 
Wherever a north and south fault is found, the block which has been thrown 
down has its lines of cliffs carried southward, or toward the axis of upheaval, 
