32 GEOLOGY OF THE HIGH PLATEAUS. 



direction; i. e., the throw north of the zero point is to the east while south 

 of this point it is to the west. The fault with its throw reversed now con- 

 tinues northward, crossing the lower end of San Pete Valley, and becomes 

 the eastern wall of the San Pete Plateau, its shear increasing until it reaches 

 nearly to Mount Nebo. It has not been traced farther, but where it has 

 last been verified it is still in considerable force. The length of this dis- 

 placement, so far as now known, is nearly 220 miles It forms the western 

 fronts of the Paunsagunt and Sevier Plateaus and the eastern front of the 

 San Pete Plateau. 



The Western Kaihah fault is the fifth great displacement. It is supposed 

 at its southern extension across the Grand Canon to unite with the Eastern 

 Kaibab fault, as it is known to do at its northern end at Paria, about 40 

 miles north of the head of Marble Canon. Its trend describes a large bow, 

 of which the Eastern Kaibab fault is the chord. Between them the Kaibab 

 Plateau has been uplifted. Through the portions immediately north of the 

 Grand Canon it is stepped, but the steps unite into a true monoclinal flexure 

 opposite the middle of the Plateau. Towards the north it gradually dies 

 out, and near the junction with the Eastern Kaibab displacement it is but 

 a gentle monoclinal swell and hardly perceptible. 



The Eastern Kaibab fault is the longest line of displacement of which 

 I have ever heard. It comes up out of unknown regions in Arizona from 

 the vicinity of the San Francisco Mountain, and appears near the mouth of 

 the Little Colorado River as a double displacement, but probably consider- 

 ably complicated.* The displacement has two parallel branches, which 

 appear to be faults where they cross the Colorado, but about 10 miles 

 northward they gradually pass into two beautiful monoclinal flexures, the 

 strata being unbroken, except by erosion at the surface. At House Rock Val- 

 ley the two flexures merge into one, which continues northward past Paria, 

 trending first northnortheast, but gradually swinging in a curve around to 

 the northwest, always preserving its true monoclinal form. As it approaches 

 "^rable Clifi", it dwindles as if about to die out; but opposite the southwest angle 



* Professor Powell is probably tbe only geologist who has seen these faults in this locality. The 

 place is a terrible one to reach jinless by boats through the entire length of the Marble CaCon, and even 

 then the approach is formidable. He would be a bold mrn who should endeavor to reach the locality 

 from above. 



