24 GEOLOGY OF THE HIGH PLATEAUS. 



Eocene, the High Plateaus have risen from 10,000 to 12,000 feet, while the 

 adjoining Basin areas have risen from 5,000 to 6,000. As we pass from 

 the Basin eastward and ascend the High Plateaus we mount the long slopes 

 of great monoclinal flexures, or scale the giant cliffs which had their origin 

 in the long major faults which traverse the district from south to north. 

 As we pass westward from the heart of the Plateau Province and ascend 

 the High Plateaus, we ascend cliffs of erosion. The fact that those cliffs 

 which had their origin in displacement, with very rare exceptions, face west- 

 ward, has attracted much attention and has received various interpretations. 

 It seems to me that the explanation is exceedingly, almost amusingly, 

 simple. The country to the east of them, and also the belt of country 

 which they occupy, has been elevated from 5,000 to 6,500 feet above the 

 country to the west of them. These figures express, of course, relative 

 vertical displacements. The passage from west to east across the belt of 

 country, which may be called the border-land between the two provinces, 

 discloses a succession of faults and monoclinal flexures which are the 

 obvious results of such a displacement. 



