North of the Grand Cation of the Colorado. 459 
It will be seen from this description that to go from the bot- 
tom of the Grand Cafion to the summit of these plateaus, you 
must climb by a great geographical stairway, the steps of whic 
ave an attitude of many hundreds of feet, and a width of 
many miles. As the rocks dip to the north, the difference in alti- 
tude between the two points is only about 7,000 feet; but were 
the beds horizontal, the plateau would be more than twice that 
height above the river. 
the present to discuss this subject. 
The lines of cliffs which have a northerly and southerly 
trend are due to abrupt displacements of the strata, either by 
faulting or folding. T ro call these displacements 
broken folds, for reasons which will subsequently appear. 
On the east side of the Grand Wash we discover a great 
arallel to the first; the drop of the b ; 
t extends from an unknown point south of the Colorado, in 
which direction it has been traced about thirty miles without 
discovering its terminus, to a point north of Tokerville. Its 
northern terminus has not yet been discovered. The displace- 
ment is from 1,300 to 2,800 feet. To the south it is a fault, 
but farther to the north it is seen to change gradually toa 
monoclinal fold. The broken edges of the rocks on the eastern 
side of the fault, which have not been displaced, stand in a 
remarkably steep es ent, in much of its course a sheer 
precipice, impossible to ae sealed even by men accustomed to 
Am. Jour. auetie eens Vou. V, No. 30.—Junz, 1873. * 
